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  • Periodicals Archive Online (PAO)  (5.724)
  • Cambridge University Press  (1.387)
  • 2020-2023  (19)
  • 1935-1939  (7.092)
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  • 1
    Publikationsdatum: 2022-06-22
    Beschreibung: Pliocene–Quaternary faults are relevant structures with which to constrain the seismotectonic context and contribute to the evaluation of the seismic hazard of a region. Many of these faults, however, do not show clear surface evidence even when releasing earthquakes. For these reasons they can be extremely dangerous as they receive relatively little attention and can be difficult to identify. From among the various surface geology studies and/or palaeoseismological investigations, we focus our attention on the integration of different datasets such as seismic reflection profiles, surface kinematic data and the relocation of seismological data, which make it possible to identify and characterize active faults whose dimension and earthquake potential would otherwise not be large enough to make them identifiable. We take as an example the Montespertoli NE-trending fault in southern Tuscany (central Italy) with which we associate the 2016 M=3.9 Castelfiorentino earthquake. This structure is part of a wider (in the order of 15–20 km) crustal-scale shear zone, which may be responsible for strong historical earthquakes in the area.
    Beschreibung: Published
    Beschreibung: 853 - 872
    Beschreibung: 4T. Sismicità dell'Italia
    Beschreibung: JCR Journal
    Schlagwort(e): active faults ; seismic faults ; Earthquakes ; strike-slip faults ; inner Northern Apennines ; solid earth
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 2
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    Cambridge University Press
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in McNichol, A., Key, R., & Guilderson, T. Global ocean radiocarbon programs. Radiocarbon, (2022): 1–13, https://doi.org/10.1017/rdc.2022.17.
    Beschreibung: The importance of studying the radiocarbon content of dissolved inorganic carbon (DI14C) in the oceans has been recognized for decades. Starting with the GEOSECS program in the 1970s, 14C sampling has been a part of most global survey programs. Early results were used to study air-sea gas exchange while the more recent results are critical for helping calibrate ocean general circulation models used to study the effects of climate change. Here we summarize the major programs and discuss some of the important insights the results are starting to provide.
    Beschreibung: Authors received funding from the National Science Foundation OCE-85865400 (APM) and a Woods Hole Oceanographic Technical Staff Award (APM).
    Schlagwort(e): Dissolved inorganic carbon ; Ocean models ; Oceanography ; Radiocarbon
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 3
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Druffel, E., Beaupre, S., Grotheer, H., Lewis, C., McNichol, A., Mollenhauer, G., & Walker, B. Marine organic carbon and radiocarbon – present and future challenges. Radiocarbon, (2022): 1-17, https://doi.org/10.1017/RDC.2021.105.
    Beschreibung: We discuss present and developing techniques for studying radiocarbon in marine organic carbon (C). Bulk DOC (dissolved organic C) Δ14C measurements reveal information about the cycling time and sources of DOC in the ocean, yet they are time consuming and need to be streamlined. To further elucidate the cycling of DOC, various fractions have been separated from bulk DOC, through solid phase extraction of DOC, and ultrafiltration of high and low molecular weight DOC. Research using 14C of DOC and particulate organic C separated into organic fractions revealed that the acid insoluble fraction is similar in 14C signature to that of the lipid fraction. Plans for utilizing this methodology are described. Studies using compound specific radiocarbon analyses to study the origin of biomarkers in the marine environment are reviewed and plans for the future are outlined. Development of ramped pyrolysis oxidation methods are discussed and scientific questions addressed. A modified elemental analysis (EA) combustion reactor is described that allows high particulate organic C sample throughput by direct coupling with the MIniCArbonDAtingSystem.
    Schlagwort(e): CSRA ; Dissolved organic carbon ; Methodology ; Organic carbon ; Radiocarbon
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 4
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Priscu, J. C., Kalin, J., Winans, J., Campbell, T., Siegfried, M. R., Skidmore, M., Dore, J. E., Leventer, A., Harwood, D. M., Duling, D., Zook, R., Burnett, J., Gibson, D., Krula, E., Mironov, A., McManis, J., Roberts, G., Rosenheim, B. E., Christner, B. C., Kasic, K., Fricker, H. A., Lyons, W. B., Barker, J., Bowling, M., Collins, B., Davis, C., Gagnon, A., Gardner, C., Gustafson, C., Kim, O-S., Li, W., Michaud, A., Patterson, M. O., Tranter, M., Ryan Venturelli, R., Trista Vick-Majors, T., & Elsworth, C. Scientific access into Mercer Subglacial Lake: scientific objectives, drilling operations and initial observations. Annals of Glaciology, 62(85–86), (2021): 340–352, https://doi.org/10.1017/aog.2021.10.
    Beschreibung: The Subglacial Antarctic Lakes Scientific Access (SALSA) Project accessed Mercer Subglacial Lake using environmentally clean hot-water drilling to examine interactions among ice, water, sediment, rock, microbes and carbon reservoirs within the lake water column and underlying sediments. A ~0.4 m diameter borehole was melted through 1087 m of ice and maintained over ~10 days, allowing observation of ice properties and collection of water and sediment with various tools. Over this period, SALSA collected: 60 L of lake water and 10 L of deep borehole water; microbes 〉0.2 μm in diameter from in situ filtration of ~100 L of lake water; 10 multicores 0.32–0.49 m long; 1.0 and 1.76 m long gravity cores; three conductivity–temperature–depth profiles of borehole and lake water; five discrete depth current meter measurements in the lake and images of ice, the lake water–ice interface and lake sediments. Temperature and conductivity data showed the hydrodynamic character of water mixing between the borehole and lake after entry. Models simulating melting of the ~6 m thick basal accreted ice layer imply that debris fall-out through the ~15 m water column to the lake sediments from borehole melting had little effect on the stratigraphy of surficial sediment cores.
    Beschreibung: This material is based upon work supported by the US National Science Foundation, Section for Antarctic Sciences, Antarctic Integrated System Science program as part of the interdisciplinary (Subglacial Antarctic Lakes Scientific Access (SALSA): Integrated study of carbon cycling in hydrologically-active subglacial environments) project (NSF-OPP 1543537, 1543396, 1543405, 1543453 and 1543441). Ok-Sun Kim was funded by the Korean Polar Research Institute. We are particularly thankful to the SALSA traverse personnel for crucial technical and logistical support. The United States Antarctic Program enabled our fieldwork; the New York Air National Guard and Kenn Borek Air provided air support; UNAVCO provided geodetic instrument support. Hot water drilling activities, including repair and upgrade modifications of the WISSARD hot water drill system, for the SALSA project were supported by a subaward from the Ice Drilling Program of Dartmouth College (NSF-PLR 1327315) to the University of Nebraska-Lincoln. J. Lawrence assisted with manuscript preparation. Finally, we are grateful to C. Dean, the SALSA Project Manager, and R. Ricards, SALSA Project Coordinator at McMurdo Station, for their organizational skills, and B. Huber of Lamont-Doherty Earth Observatory for providing the SBE39 PT sensors and the Nortek Aquadopp current meter and assisting with interpretation of the data. B. Huber also provided helpful input on programing and calibrating the SBE19PlusV2 6112 CTD.
    Schlagwort(e): Antarctic glaciology ; Basal ice ; Biogeochemistry ; Glacial sedimentology ; Subglacial lakes
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 5
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    Cambridge University Press
    In:  EPIC3Climate Change 2022: Impacts, adaptation and vulnerability. Contribution of the WGII to the 6th assessment report of the intergovernmental panel on climate change, ,, IPCC AR6 WGII, https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_FinalDraft_Chapter03.pdf, Cambridge University Press
    Publikationsdatum: 2022-08-23
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Inbook , NonPeerReviewed
    Format: application/pdf
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  • 6
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    Cambridge University Press
    In:  EPIC3Climate Change 2022: Impacts, adaptation and vulnerability. Contribution of the WGII to the 6th assessment report of the intergovernmental panel on climate change, IPCC AR6 WGII, Climate Change 2022: Impacts, adaptation and vulnerability. Contribution of the WGII to the 6th assessment report of the intergovernmental panel on climate change, IPCC AR6 WGII, https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_FinalDraft_Chapter02.pdf, Cambridge University Press, 5 p., pp. 22-26
    Publikationsdatum: 2022-06-17
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Inbook , peerRev
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  • 7
    Publikationsdatum: 2022-07-20
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Tan, S., Pratt, L. J., Voet, G., Cusack, J. M., Helfrich, K. R., Alford, M. H., Girton, J. B., & Carter, G. S. Hydraulic control of flow in a multi-passage system connecting two basins. Journal of Fluid Mechanics, 940, (2022): A8, https://doi.org/10.1017/jfm.2022.212.
    Beschreibung: When a fluid stream in a conduit splits in order to pass around an obstruction, it is possible that one branch will be critically controlled while the other remains not so. This is apparently the situation in Pacific Ocean abyssal circulation, where most of the northward flow of Antarctic bottom water passes through the Samoan Passage, where it is hydraulically controlled, while the remainder is diverted around the Manihiki Plateau and is not controlled. These observations raise a number of questions concerning the dynamics necessary to support such a regime in the steady state, the nature of upstream influence and the usefulness of rotating hydraulic theory to predict the partitioning of volume transport between the two paths, which assumes the controlled branch is inviscid. Through the use of a theory for constant potential vorticity flow and accompanying numerical model, we show that a steady-state regime similar to what is observed is dynamically possible provided that sufficient bottom friction is present in the uncontrolled branch. In this case, the upstream influence that typically exists for rotating channel flow is transformed into influence into how the flow is partitioned. As a result, the partitioning of volume flux can still be reasonably well predicted with an inviscid theory that exploits the lack of upstream influence.
    Beschreibung: This work was supported by the National Science Foundation under grants OCE-1029268, OCE-1029483, OCE-1657264, OCE-1657795, OCE-1657870 and OCE-1658027.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 8
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Xu, L., Roberts, M., Elder, K., Hansman, R., Gagnon, A., & Kurz, M. Radiocarbon in dissolved organic carbon by UV oxidation: an update of procedures and blank characterization at NOSAMS. Radiocarbon, 64(1), (2022): 195-199, https://doi.org/10.1017/rdc.2022.4.
    Beschreibung: This note describes improvements of UV oxidation method that is used to measure carbon isotopes of dissolved organic carbon (DOC) at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS). The procedural blank is reduced to 2.6 ± 0.6 μg C, with Fm of 0.42 ± 0.10 and δ13C of –28.43 ± 1.19‰. The throughput is improved from one sample per day to two samples per day.
    Beschreibung: We gratefully acknowledge support from the U.S. National Science Foundation, via NSF-OCE-1755125.
    Schlagwort(e): Blank ; Dissolved organic carbon ; Radiocarbon ; UV-oxidation
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 9
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    Cambridge University Press
    In:  EPIC3Antarctic Science, Cambridge University Press, 33(6), pp. 575-595, ISSN: 0954-1020
    Publikationsdatum: 2022-01-13
    Beschreibung: The waters along the West Antarctic Peninsula (WAP) have experienced warming and increased freshwater inputs from melting sea ice and glaciers in recent decades. Challenges exist in understanding the consequences of these changes on the inorganic carbon system in this ecologically important and highly productive ecosystem. Distributions of dissolved inorganic carbon (CT), total alkalinity (AT) and nutrients revealed key physical, biological and biogeochemical controls of the calcium carbonate saturation state (Ωaragonite) in different water masses across the WAP shelf during the summer. Biological production in spring and summer dominated changes in surface water Ωaragonite (ΔΩaragonite up to +1.39; ∼90%) relative to underlying Winter Water. Sea-ice and glacial meltwater constituted a minor source of AT that increased surface water Ωaragonite (ΔΩaragonite up to +0.07; ∼13%). Remineralization of organic matter and an influx of carbon-rich brines led to cross-shelf decreases in Ωaragonite in Winter Water and Circumpolar Deep Water. A strong biological carbon pump over the shelf created Ωaragonite oversaturation in surface waters and suppression of Ωaragonite in subsurface waters. Undersaturation of aragonite occurred at 〈 ∼1000 m. Ongoing changes along the WAP will impact the biologically driven and meltwater-driven processes that influence the vulnerability of shelf waters to calcium carbonate undersaturation in the future.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev , info:eu-repo/semantics/article
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  • 10
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Baker, M. G., Aster, R. C., Wiens, D. A., Nyblade, A., Bromirski, P. D., Gerstoft, P., & Stephen, R. A. Teleseismic earthquake wavefields observed on the Ross Ice Shelf. Journal of Glaciology, 67(261), (2021): 58-74, https://doi.org/10.1017/jog.2020.83.
    Beschreibung: Observations of teleseismic earthquakes using broadband seismometers on the Ross Ice Shelf (RIS) must contend with environmental and structural processes that do not exist for land-sited seismometers. Important considerations are: (1) a broadband, multi-mode ambient wavefield excited by ocean gravity wave interactions with the ice shelf; (2) body wave reverberations produced by seismic impedance contrasts at the ice/water and water/seafloor interfaces and (3) decoupling of the solid Earth horizontal wavefield by the sub-shelf water column. We analyze seasonal and geographic variations in signal-to-noise ratios for teleseismic P-wave (0.5–2.0 s), S-wave (10–15 s) and surface wave (13–25 s) arrivals relative to the RIS noise field. We use ice and water layer reverberations generated by teleseismic P-waves to accurately estimate the sub-station thicknesses of these layers. We present observations consistent with the theoretically predicted transition of the water column from compressible to incompressible mechanics, relevant for vertically incident solid Earth waves with periods longer than 3 s. Finally, we observe symmetric-mode Lamb waves generated by teleseismic S-waves incident on the grounding zones. Despite their complexity, we conclude that teleseismic coda can be utilized for passive imaging of sub-shelf Earth structure, although longer deployments relative to conventional land-sited seismometers will be necessary to acquire adequate data.
    Beschreibung: This research was supported by NSF grants PLR-1142518, 1141916, 1142126, 1246151, 1246416 and OPP-1744852 and 1744856.
    Schlagwort(e): Glacier geophysics ; Ice shelves ; Seismology
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 11
    Publikationsdatum: 2022-05-27
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Tison, J.-L., Maksym, T., Fraser, A. D., Corkill, M., Kimura, N., Nosaka, Y., Nomura, D., Vancoppenolle, M., Ackley, S., Stammerjohn, S., Wauthy, S., Van der Linden, F., Carnat, G., Sapart, C., de Jong, J., Fripiat, F., & Delille, B. Physical and biological properties of early winter Antarctic sea ice in the Ross Sea. Annals of Glaciology, 61(83), (2020): 241–259, https://doi.org/10.1017/aog.2020.43.
    Beschreibung: This work presents the results of physical and biological investigations at 27 biogeochemical stations of early winter sea ice in the Ross Sea during the 2017 PIPERS cruise. Only two similar cruises occurred in the past, in 1995 and 1998. The year 2017 was a specific year, in that ice growth in the Central Ross Sea was considerably delayed, compared to previous years. These conditions resulted in lower ice thicknesses and Chl-a burdens, as compared to those observed during the previous cruises. It also resulted in a different structure of the sympagic algal community, unusually dominated by Phaeocystis rather than diatoms. Compared to autumn-winter sea ice in the Weddell Sea (AWECS cruise), the 2017 Ross Sea pack ice displayed similar thickness distribution, but much lower snow cover and therefore nearly no flooding conditions. It is shown that contrasted dynamics of autumnal-winter sea-ice growth between the Weddell Sea and the Ross Sea impacted the development of the sympagic community. Mean/median ice Chl-a concentrations were 3–5 times lower at PIPERS, and the community status there appeared to be more mature (decaying?), based on Phaeopigments/Chl-a ratios. These contrasts are discussed in the light of temporal and spatial differences between the two cruises.
    Beschreibung: S. Stammerjohn was supported by the PIPERS and LTER Programs of the U.S. National Science Foundation, ANT-1341606 (S. Stammerjohn and J. Cassano, U Colorado) and ANT-0823101 (H. Ducklow, LDEO/Columbia University), respectively. Steve Ackley (UTSA) was supported by the PIPERS program of the U.S. National Science Foundation ANT-1341717 and by NASA Grant 80NSSC19M0194 to the Center for Adv. Meas. in Extreme Environments at UTSA.Ted Maksym (WHOI) was supported by the PIPERS program of the U.S. National Science Foundation ANT-1341513. This research was supported by the Belgian F.R.S-FNRS (project ISOGGAP and IODIne, contract T.0268.16 and J.0262.17, respectively). Fanny Van der Linden, Sarah Wauthy, Gauthier Carnat, Célia Sapart and Bruno Delille are PhD students, postdoctoral researchers and research associate, respectively, of the Belgian F.R.S.-FNRS. This work was also supported by the Australian Government's Cooperative Research Centre program through the Antarctic Climate & Ecosystems Cooperative Research Centre, and by the Australian Research Council's Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001). Daiki Nomura was supported by grants from the Japan Society for the Promotion of Science (#17H04715) and the National Institute for Polar Research through Project Research KP-303 (ROBOTICA) and #28-14.
    Schlagwort(e): Antarctic glaciology ; biogeochemistry ; sea ice
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 12
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in [Schiller, C. M., Whitlock, C., Elder, K. L., Iverson, N. A., & Abbott, M. B. Erroneously old radiocarbon ages from terrestrial pollen concentrates in Yellowstone Lake, Wyoming, USA. Radiocarbon, 63(1), (2021): 321-342, https://doi.org/10.1017/RDC.2020.118.
    Beschreibung: Accelerator mass spectrometry (AMS) dating of pollen concentrates is often used in lake sediment records where large, terrestrial plant remains are unavailable. Ages produced from chemically concentrated pollen as well as manually picked Pinaceae grains in Yellowstone Lake (Wyoming) sediments were consistently 1700–4300 cal years older than ages established by terrestrial plant remains, tephrochronology, and the age of the sediment-water interface. Previous studies have successfully utilized the same laboratory space and methods, suggesting the source of old-carbon contamination is specific to these samples. Manually picking pollen grains precludes admixture of non-pollen materials. Furthermore, no clear source of old pollen grains occurs on the deglaciated landscape, making reworking of old pollen grains unlikely. High volumes of CO2 are degassed in the Yellowstone Caldera, potentially introducing old carbon to pollen. While uptake of old CO2 through photosynthesis is minor (F14C approximately 0.99), old-carbon contamination may still take place in the water column or in surficial lake sediments. It remains unclear, however, what mechanism allows for the erroneous ages of highly refractory pollen grains while terrestrial plant remains were unaffected. In the absence of a satisfactory explanation for erroneously old radiocarbon ages from pollen concentrates, we propose steps for further study.
    Beschreibung: This research was supported by NSF Grant No. 1515353 to C. Whitlock and sampling in Yellowstone National Park was conducted under permits YELL-SCI-0009 and YELL-SCI-5054.
    Schlagwort(e): AMS dating ; Chronology ; Contamination ; Paleoecology ; Pine
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 13
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    Cambridge University Press
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hughen, K. A., & Heaton, T. J. Updated Cariaco Basin C-14 calibration dataset from 0-60 cal kyr BP. Radiocarbon, 62(4), (2020): 1001-1043, doi:10.1017/RDC.2020.53.
    Beschreibung: We present new updates to the calendar and radiocarbon (14C) chronologies for the Cariaco Basin, Venezuela. Calendar ages were generated by tuning abrupt climate shifts in Cariaco Basin sediments to those in speleothems from Hulu Cave. After the original Cariaco-Hulu calendar age model was published, Hulu Cave δ18O records have been augmented with increased temporal resolution and a greater number of U/Th dates. These updated Hulu Cave records provide increased accuracy as well as precision in the final Cariaco calendar age model. The depth scale for the Ocean Drilling Program Site 1002D sediment core, the primary source of samples for 14C dating, has been corrected to account for missing sediment from a core break, eliminating age-depth anomalies that afflicted the earlier calendar age models. Individual 14C dates for the Cariaco Basin remain unchanged from previous papers, although detailed comparisons of the Cariaco calibration dataset to those from Hulu Cave and Lake Suigetsu suggest that the Cariaco marine reservoir age may have shifted systematically during the past. We describe these recent changes to the Cariaco datasets and provide the data in a comprehensive format that will facilitate use by the community.
    Beschreibung: K.A. Hughen was supported by funds from U.S. NSF grant #OCE-1657191, and by the Investment in Science Fund at WHOI. T.J. Heaton is supported by a Leverhulme Trust Fellowship RF-2019-140\9, “Improving the Measurement of Time Using Radiocarbon”.
    Schlagwort(e): Calibration ; Climate ; Radiocarbon
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 14
    Publikationsdatum: 2022-10-20
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ackley, S. F., Perovich, D. K., Maksym, T., Weissling, B., & Xie, H. Surface flooding of Antarctic summer sea ice. Annals of Glaciology, 61(82), (2020): 117-126, doi:10.1017/aog.2020.22.
    Beschreibung: The surface flooding of Antarctic sea ice in summer covers 50% or more of the sea-ice area in the major summer ice packs, the western Weddell and the Bellingshausen-Amundsen Seas. Two CRREL ice mass-balance buoys were deployed on the Amundsen Sea pack in late December 2010 from the icebreaker Oden, bridging the summer period (January–February 2011). Temperature records from thermistors embedded vertically in the snow and ice showed progressive increases in the depth of the flooded layer (up to 0.3–0.35 m) on the ice cover during January and February. While the snow depth was relatively unchanged from accumulation (〈10 cm), ice thickness decreased by up to a meter from bottom melting during this period. Contemporaneous with the high bottom melting, under-ice water temperatures up to 1°C above the freezing point were found. The high temperature arises from solar heating of the upper mixed layer which can occur when ice concentration in the local area falls and lower albedo ocean water is exposed to radiative heating. The higher proportion of snow ice found in the Amundsen Sea pack ice therefore results from both winter snowfall and summer ice bottom melt found here that can lead to extensive surface flooding.
    Beschreibung: This work was supported by the National Science Foundation grant to UTSA, ANT-0839053-Sea Ice System in Antarctic Summer (S.F. Ackley, H. Xie and B. Weissling), and to WHOI, ANT-1341513 (T. Maksym), and by the NASA Center for Advanced Measurements in Extreme Environments or NASA-CAMEE at UTSA, NASA #80NSSC19M0194 (S.F. Ackley, H. Xie, B.Weissling).
    Schlagwort(e): Ice/ocean interactions ; Sea ice ; Sea-ice growth and decay ; Snow/ice surface processes
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 15
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Reimer, P. J., Austin, W. E. N., Bard, E., Bayliss, A., Blackwell, P. G., Ramsey, C. B., Butzin, M., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Hajdas, I., Heaton, T. J., Hogg, A. G., Hughen, K. A., Kromer, B., Manning, S. W., Muscheler, R., Palmer, J. G., Pearson, C., van der Plicht, J., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Turney, C. S. M., Wacker, L., Adolphi, F., Buentgen, U., Capano, M., Fahrni, S. M., Fogtmann-Schulz, A., Friedrich, R., Koehler, P., Kudsk, S., Miyake, F., Olsen, J., Reinig, F., Sakamoto, M., Sookdeo, A., & Talamo, S. The Intcal20 Northern Hemisphere radiocarbon age calibration curve (0-55 cal kBP). Radiocarbon, 62(4), (2020): 725-757, doi:10.1017/RDC.2020.41.
    Beschreibung: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.
    Beschreibung: We would like to thank the National Natural Science Foundation of China grants NSFC 41888101 and NSFC 41731174, the 111 program of China (D19002), U.S. NSF Grant 1702816, and the Malcolm H. Wiener Foundation for support for research that contributed to the IntCal20 curve. The work on the Swiss and German YD trees was funded by the German Science foundation and the Swiss National Foundation (grant number: 200021L_157187). The operation in Aix-en-Provence is funded by the EQUIPEX ASTER-CEREGE, the Collège de France and the ANR project CARBOTRYDH (to EB). The work on the correlation of tree ring 14C with ice core 10Be was partially supported by the Swedish Research Council and the Knut and Alice Wallenberg foundation. M. Butzin was supported by the German Federal Ministry of Education and Research (BMBF) as Research for Sustainable Development (FONA; http://www.fona.de) through the PalMod project (grant number: 01LP1505B). S. Talamo and M. Friedrich are funded by the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement No. 803147-RESOLUTION, awarded to ST). CA. Turney would like to acknowledge support of the Australian Research Council (FL100100195 and DP170104665). P. Reimer and W. Austin acknowledge the support of the UKRI Natural Environment Research Council (Grant NE/M004619/1). T.J. Heaton is supported by a Leverhulme Trust Fellowship RF-2019-140\9. Other datasets and the IntCal20 database were created without external support through internal funding by the respective laboratories. We also would like to thank various institutions that provided funding or facilities for meetings.
    Schlagwort(e): Calibration curve ; Radiocarbon ; IntCal20
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  • 16
    Publikationsdatum: 2022-05-26
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Heaton, T. J., Koehler, P., Butzin, M., Bard, E., Reimer, R. W., Austin, W. E. N., Ramsey, C. B., Grootes, P. M., Hughen, K. A., Kromer, B., Reimer, P. J., Adkins, J., Burke, A., Cook, M. S., Olsen, J., & Skinner, L. C. Marine20-the marine radiocarbon age calibration curve (0-55,000 cal BP). Radiocarbon, 62(4), (2020): 779-820, doi:10.1017/RDC.2020.68.
    Beschreibung: The concentration of radiocarbon (14C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0–55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is intended for calibration of marine radiocarbon samples from non-polar regions; it is not suitable for calibration in polar regions where variability in sea ice extent, ocean upwelling and air-sea gas exchange may have caused larger changes to concentrations of marine radiocarbon. The Marine20 curve is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realizations of our Northern Hemispheric atmospheric IntCal20 14C curve and reconstructed changes in CO2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for ΔR, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/.
    Beschreibung: We would like to thank Jeremy Oakley and Richard Bintanja for informative discussions during the development of this work. T.J. Heaton is supported by a Leverhulme Trust Fellowship RF-2019-140\9, “Improving the Measurement of Time Using Radiocarbon”. M Butzin is supported by the German Federal Ministry of Education and Research (BMBF), as Research for Sustainability initiative (FONA); www.fona.de through the PalMod project (grant numbers: 01LP1505B, 01LP1919A). E. Bard is supported by EQUIPEX ASTER-CEREGE and ANR CARBOTRYDH. Meetings of the IntCal Marine Focus group have been supported by Collège de France. Data are available on the PANGAEA database at doi:10.159/ANGAEA.914500.
    Schlagwort(e): Bayesian modeling ; calibration ; carbon cycle ; computer model ; marine environment
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  • 17
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Roberts, Mark L., Elder, Kathryn L., Jenkins, William J., Gagnon, Alan R., Xu, Li, Hlavenka, Joshua D., & Longworth, Brett E. C-14 Blank Corrections for 25-100 mu G samples at the National Ocean Sciences AMS Laboratory. Radiocarbon, 61(5), (2019): 1403-1411, Doi: 10.1017/RDC.2019.74.
    Beschreibung: Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0–1.5 and mass range 6 μg–2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently “blank correct” measured unknowns in the mass range 25–100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented.
    Beschreibung: This work is supported by a Cooperative Agreement (OCE-1755125) with the U.S. National Science Foundation.
    Schlagwort(e): AMS ; AMS dating ; Blank corrections
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  • 18
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Baker, M. G., Aster, R. C., Anthony, R. E., Chaput, J., Wiens, D. A., Nyblade, A., Bromirski, P. D., Gerstoft, P., & Stephen, R. A. Seasonal and spatial variations in the ocean-coupled ambient wavefield of the Ross Ice Shelf. Journal of Glaciology, 65(254), (2019): 912-925, doi:10.1017/jog.2019.64.
    Beschreibung: The Ross Ice Shelf (RIS) is host to a broadband, multimode seismic wavefield that is excited in response to atmospheric, oceanic and solid Earth source processes. A 34-station broadband seismographic network installed on the RIS from late 2014 through early 2017 produced continuous vibrational observations of Earth's largest ice shelf at both floating and grounded locations. We characterize temporal and spatial variations in broadband ambient wavefield power, with a focus on period bands associated with primary (10–20 s) and secondary (5–10 s) microseism signals, and an oceanic source process near the ice front (0.4–4.0 s). Horizontal component signals on floating stations overwhelmingly reflect oceanic excitations year-round due to near-complete isolation from solid Earth shear waves. The spectrum at all periods is shown to be strongly modulated by the concentration of sea ice near the ice shelf front. Contiguous and extensive sea ice damps ocean wave coupling sufficiently so that wintertime background levels can approach or surpass those of land-sited stations in Antarctica.
    Beschreibung: This research was supported by NSF grants PLR-1142518, 1141916, 1142126, 1246151 and 1246416. JC was additionally supported by Yates funds in the Colorado State University Department of Mathematics. PDB also received support from the California Department of Parks and Recreation, Division of Boating and Waterways under contract 11-106-107. We thank Reinhard Flick and Patrick Shore for their support during field work, Tom Bolmer in locating stations and preparing maps, and the US Antarctic Program for logistical support. The seismic instruments were provided by the Incorporated Research Institutions for Seismology (IRIS) through the PASSCAL Instrument Center at New Mexico Tech. Data collected are available through the IRIS Data Management Center under RIS and DRIS network code XH. The PSD-PDFs presented in this study were processed with the IRIS Noise Tool Kit (Bahavar and others, 2013). The facilities of the IRIS Consortium are supported by the National Science Foundation under Cooperative Agreement EAR-1261681 and the DOE National Nuclear Security Administration. The authors appreciate the support of the University of Wisconsin-Madison Automatic Weather Station Program for the data set, data display and information; funded under NSF grant number ANT-1543305. The Ross Ice Shelf profiles were generated using the Antarctic Mapping Tools (Greene and others, 2017). Regional maps were generated with the Generic Mapping Tools (Wessel and Smith, 1998). Topography and bathymetry data for all maps in this study were sourced from the National Geophysical Data Center ETOPO1 Global Relief Model (doi:10.7289/V5C8276M). We thank two anonymous reviewers for suggestions on the scope and organization of this paper.
    Schlagwort(e): Antarctic glaciology ; Ice shelves ; Seismology
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  • 19
    Publikationsdatum: 2022-10-21
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ackley, S. F., Stammerjohn, S., Maksym, T., Smith, M., Cassano, J., Guest, P., Tison, J., Delille, B., Loose, B., Sedwick, P., DePace, L., Roach, L., & Parno, J. Sea-ice production and air/ice/ocean/biogeochemistry interactions in the Ross Sea during the PIPERS 2017 autumn field campaign. Annals of Glaciology, 61(82), (2020): 181-195, doi:10.1017/aog.2020.31.
    Beschreibung: The Ross Sea is known for showing the greatest sea-ice increase, as observed globally, particularly from 1979 to 2015. However, corresponding changes in sea-ice thickness and production in the Ross Sea are not known, nor how these changes have impacted water masses, carbon fluxes, biogeochemical processes and availability of micronutrients. The PIPERS project sought to address these questions during an autumn ship campaign in 2017 and two spring airborne campaigns in 2016 and 2017. PIPERS used a multidisciplinary approach of manned and autonomous platforms to study the coupled air/ice/ocean/biogeochemical interactions during autumn and related those to spring conditions. Unexpectedly, the Ross Sea experienced record low sea ice in spring 2016 and autumn 2017. The delayed ice advance in 2017 contributed to (1) increased ice production and export in coastal polynyas, (2) thinner snow and ice cover in the central pack, (3) lower sea-ice Chl-a burdens and differences in sympagic communities, (4) sustained ocean heat flux delaying ice thickening and (5) a melting, anomalously southward ice edge persisting into winter. Despite these impacts, airborne observations in spring 2017 suggest that winter ice production over the continental shelf was likely not anomalous.
    Beschreibung: NSF supported PIPERS award numbers: ANT-1341717 (S.F. Ackley, UTSA); ANT-1341513 (E. Maksym, WHOI); ANT-1341606 (S. Stammerjohn and J. Cassano, U Colorado); ANT-1341725 (P. Guest, NPS). P. Sedwick was supported by NSF ANT-1543483. S.F. Ackley was also supported by NASA Grant 80NSSC19M0194 to the Center for Advanced Measurements in Extreme Environments at UTSA. S. Stammerjohn was also supported by the LTER Program under NFS award number ANT-0823101 (H. Ducklow, LDEO/Columbia University). Additional support was by the Belgian F.R.S-FNRS (project ISOGGAP and IODIne, contract T.0268.16 and J.0262.17, respectively). Bruno Delille is a research associate of the F.R.S.-FNRS. Terra-Sar-X quicklook imagery was coordinated by Kathrin Hoeppner at DLR, and Andy Archer (with the Antarctic Support Contractor) provided selected (cloud-free) MODIS scenes and daily maps of AMSR2 sea-ice concentration.
    Schlagwort(e): Atmosphere/ice/ocean interactions ; Ice/ocean interactions ; Sea ice ; Sea-ice growth and decay
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  • 20
    Publikationsdatum: 1939-01-01
    Print ISSN: 0032-2474
    Digitale ISSN: 1475-3057
    Thema: Ethnologie , Geographie
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  • 21
    Publikationsdatum: 1939-10-01
    Beschreibung: Sulphate of ammonia and nitrate of soda, applied at monthly intervals, produced increases in the carotene content of poor pasture grass amounting to 28%. Sulphate of potash, also applied monthly, produced an increase of 6·2%. A single dressing of carbonate of lime, which was sufficient to satisfy the lime requirement of the soil, produced no effect on carotene content, whilst monthly dressings of superphosphate also had no influence except in the month of June, when an increase of 14·5% was produced. All five manurial treatments significantly increased the yields of dry matter and carotene.Carotene contents were very low during the drought experienced in April and May 1938, increased significantly in June, and showed very marked and highly significant increases in the autumn months.Ash content was increased by the three non-nitrogenous manures, and protein content by nitrate of soda, sulphate of ammonia and superphosphate. Ether extract was increased by superphosphate and sulphate of ammonia, whilst nitrogen-free extract was decreased under all manurial treatments except carbonate of lime. None of the five artificial fertilizers had any effect on the mean fibre content of the grass, although various significant differences were observed on certain sampling occasions. Normal seasonal variations occurred in the percentages of ash and organic constituents.Correlations of carotene with crude protein, fibre, nitrogen-free extract and ash have been computed for each manurial treatment and several significant differences have been observed. The physiological significance of these correlations has been briefly discussed.
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    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
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  • 22
    Publikationsdatum: 1939-10-01
    Beschreibung: The amount of oil in the diet and its degree of unsaturation are known to exert an important effect on the nature of the fat deposited in the body of the growing pig, foods of high oil content tending to give rise to bacon carcasses containing fat of an undesirably soft and unsaturated character. For this reason, authorities on pig nutrition are agreed on the desirability of excluding from the dietary of the bacon pig all foods containing more than a small percentage of oil. It has been stated that, in order to avoid the danger of producing carcasses with soft fat, the meal ration of the fattening pig should be made up so as to contain no more than about 3% of oil.This prejudice against the use of feeding stuffs rich in oil has been transferred, somewhat unquestioningly perhaps, to feeding stuffs rich in fat. Feeding meat meal, for example, contains normally from 8 to 10 % of fat, and manufacturers complain of the difficulty of securing sales of this product for pig-feeding on account of the view generally held that its high fat content would occasion the production of soft fat in the resultant bacon or a carcass with an excessive amount of fat. To meet this prejudice, therefore, the meat meal as ordinarily produced is frequently submitted to a process of de-greasing with petroleum benzine at about 200° F. so as to give a meat meal containing about 3% of fat. This procedure, however, not only adds to the cost of the manufacture of meat meal, but may actually lead to a distinct lowering of the digestibility of the product (Woodman & Evans, 1937).
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  • 23
    Publikationsdatum: 1939-10-01
    Beschreibung: 1. By establishing the relationship between linear carcass measurements and the quantitative composition of the carcass in terms of bone, muscle and fat, we have provided a scientific basis for the use of many measurements hitherto only presumed to provide an index to carcass quality.2. External carcass measurements are correlated with weight of the skeleton. The most useful for this purpose are length of tibia + tarsus and length of the fore-cannon.3. As indices of muscle, external measures are only of indirect value. Thus, both F – T and G/F × 100 are strongly correlated with weight of muscle as a percentage of skeletal weight.4. Similarly, F provides an index of fat, being negatively correlated with fat as a percentage of bone.5. For muscle and fat internal measures permit a more precise estimate to be made. A + B is the best index of the former while C + J + Y provide the most accurate estimate of the weight of fat.6. Still better indices for muscle and fat are provided by suitable combinations of external and internal measurements. Thus L/10 + A + B is very highly correlated with the weight of muscle, and L/10 × (C + J + Y) is the best index of fat in the hoggets. For bone, a most efficient single index is shown to be the weight of the fore-cannon bone.7. The weight of the skeleton can be estimated with a high degree of accuracy from the weight of the bones in either one leg or loin. Both these joints combined, however, provide a still better estimate.8. The muscle in one leg or loin + leg provides an excellent index of the weight of muscle in the whole carcass.9. The fat in one leg, loin, or both these joints combined provides a good index of the weight of the total fat in the carcass. Both joints combined give the most precise measure.10. The value of certain measurements which are not necessarily associated with the quantity of the major tissues of the carcass, but which nevertheless have important qualitative significance, is emphasized.
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  • 24
    Publikationsdatum: 1939-07-01
    Beschreibung: 1. In mares which had a follicle of a sufficient size in the ovaries, in most cases the intravenous injection of 1000 mouse units or over of pregnancy urine extract caused ovulation at any time in the oestrous cycle.2. In those mares which were in oestrus at the time of injection, ovulation occurred 22–30 hr. after injection, and the length of oestrus was reduced from 7 and 9 days to 3 days.3. In those mares which were not in oestrus when injected ovulation occurred 30–60 hr. after injection without the appearance of any symptoms of oestrus.4. Normal ovulation occurred after these injections, and in one case the ovum was recovered from the uterine end of the Fallopian tube about 95 hr. after ovulation, and 138 hr. after injection.
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  • 25
    Publikationsdatum: 1939-01-01
    Beschreibung: The design and field technique of two large scale experiments, laid down to investigate the problems of sampling and “propinquity”, are described in detail. These experiments were designed so that the plant number, stem number, ear number, straw weight and grain weight for 7200 lengths of 6 in. of drill row, together with the position of each observation, might be obtained.The lowest sampling error, expressed as a percentage of the mean, is obtained by using the smallest sampling unit, but the large number of sampling units of this size that would have to be taken make it impracticable. The optimum sampling unit consists of 6 ft. of drill row, taken as 3 ft. of two adjacent rows. The size of the sampling unit is of greater importance than the shape in determining its accuracy, and little s lost by using sampling units of 18 in. of five adjacent rows.The nature of the observation affects the degree of sampling. In the experiments examined the plant number, stem number and ear number require very similar sampling, but grain weight requires a sample which is about twice as large as that required by the other observations.The percentage of the plot that must be taken as a sample (the sampling percentage) to obtain any given accuracy is related to the size of plot: the larger the plot, the lower the sampling percentage necessary. To obtain an error of 5% of the mean the sampling percentage for grain weight is approximately 5% in 1/20 acre plots, 15% in 1/100 acre plots and 43% in 1/600 acre plots if the plots are not subdivided. These percentages are similar to those calculated from various randomized block experiments in Cambridge.
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  • 26
    Publikationsdatum: 1939-07-01
    Beschreibung: 1. The removal of the foetus between the 51st and 105th day of pregnancy in the mare, did not have any detrimental effect in seven Welsh pony mares.2. The subsequent oestrous cycles of the mares did not appear to be influenced by the stage of pregnancy at which the foetus was removed.
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  • 27
    Publikationsdatum: 1939-07-01
    Beschreibung: An account is given of the results of two series of field experiments carried out at Rothamsted and Woburn in the years 1926 to 1936 on the effect of nitrogenous fertilizers on wheat. In the first series a comparison was made of the effects of early (March) and late (May) top-dressings, and in the second series a range of times of application from sowing to the end of May were tested.At Rothamsted, the increases of yield of grain produced by the nitrogenous fertilizer were small and rarely significant, but they were greater at Woburn. On the average of all experiments, the effect of the fertilizer on yield of grain was independent of the time of application. In individual years, variation in effectiveness between times of application was found, and this was correlated with the amount of rain falling in a short period after the time of application. At Woburn, the effectiveness of the fertilizer decreased with increase in the amount of rain falling immediately after the application of the fertilizer, but at Rothamsted the effects were less clear and appeared to be in the opposite direction.The effects on straw yield were relatively greater, and more consistent, than those on grain yield. A greater increase of straw yield was produced by early top-dressing (January–March) than by application at the time of sowing, and the increase declined steadily the later the time of topdressing. Shoot height was increased by the nitrogenous fertilizer, and varied with time of application in a similar manner to straw yield.
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    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
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  • 28
    Publikationsdatum: 1939-07-01
    Beschreibung: A method is described whereby solutions can be obtained from wheat leaves which are toxic to the spores of rusts. Precautions designed to minimize unknown variable factors affecting the activity of the solutions are described.It was found that the uredospores used germinated better in extracts from Little Joss wheat infected with Tilletia tritici than in that from healthy plants, this being correlated with the relative susceptibility of the two kinds of plant under field conditions. On the other hand, no correlation was obtained as between four different varieties tested in the healthy state.A method is described, by which solutions are obtained in which enzymic activity in the course of preparation is reduced to a minimum. It is found that solutions prepared in this way are non-toxic, if obtained from healthy living leaves, though present in decaying leaves. It is deduced that the toxic substances studied are formed in the course of autolysis.It is found that, using the second method of preparation, solutions obtained from rusted leaves are toxic. An experiment is described in which modifications of the degree to which such toxins are produced by a given amount of rust infection are brought about by different nutritional treatments, excess of potassium and deficiency of minor elements being conducive to the production of toxins.Experiments are described which demonstrate that the toxins produced by infection with Puccinia glumarum are toxic only to spores of that species, and not to those of P. triticina, and vice versa.
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    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
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  • 29
    Publikationsdatum: 1939-07-01
    Beschreibung: The object of this experiment was, in the first place, to see whether, with cotton experiments, there was an advantage in planting a larger number of seeds per hill than the customary number of three; and, in the second place, to see the effect of the interaction of time of thinning with varying numbers of seeds per hill.In cotton breeding work, where trials of new strains have to be carried out as soon as sufficient seed is available, it is important to conserve seed in all possible ways. At the same time it is necessary to plant sufficient seed to give a full and even stand for all strains.In experiments carried out in 1936–7 and 1937–8 stand counts, made soon after germination, showed the advantage of the higher seed rates in obtaining a quick and full stand. Later counts and final counts at harvest showed a considerable evening up, although the two-seed treatment proved unreliable, giving the lowest stand in both seasons.Plant height and weight records, made during both seasons, showed that plants from the larger hills were drawn up much more rapidly than plants from the smaller hills. This rapid elongation in stem height proved, from weight figures, to be at the expense of lateral development, weak and leggy plants being produced in these hills. The ten-seed treatment showed up particularly badly in this respect, the yield figures showing that the plants never recovered from this early deleterious effect.The six-seed treatment, whilst giving a quick and excellent stand suffered to a certain extent from the same defects as the ten-seed treatment. If thinned early they tended to fill out and become more comparable with plants from the three-seed treatment, but when thinning was delayed they never caught up and final yield suffered adversely.
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    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
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  • 30
    Publikationsdatum: 1939-07-01
    Beschreibung: Some years ago my colleague, Mr E. T. Halnan, suggested the construction of the present instrument for the purpose of determining figures for domestic fowls corresponding to those of Kellner for ruminants.Owing to the activity of the fowl, it is essential that an instrument for this purpose should be capable of recording accurately a heat output which may be varying with some rapidity.From this point of view the advantages of the indirect method were considered but were eventually rejected for the following reasons: (a) the advantage accruing from our greater experience of the direct method in this laboratory, (b) the work of Adams & Poulton (1933, 1934, 1935) calling in question the fundamental bases of the indirect method, and (c) the very variable R.Q.'S obtained in earlier work by numerous investigators working with birds.That the decision was wise soon became apparent when work on birds was begun. It is certain that no ordinary apparatus of that kind could possibly take account of the variations caused by the constant changes in activity.The principle of a “compensatory” or “balanced” calorimeter more or less as developed by Noyons (1927), Benedict (1927) and Heyster (1933), was selected as the most likely to give promptness in registration, and this choice has been amply justified in the result. Such instruments can be very lightly constructed, although where living animals are concerned, since their movements cannot be controlled, as can those of a human being, a greater margin of strength has to be provided, which naturally increases the heat capacity and lag and reduces sensitivity to small changes in heat evolution.
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  • 31
    Publikationsdatum: 1939-07-01
    Beschreibung: Artificially dried potatoes are being marketed in this country at the present time in two grades, known as potato cossettes and potato meal. “Chat” potatoes are first washed in water tanks provided with revolving paddles and are then elevated into a machine that pulps them into pieces about the size of fingers. The resulting cossettes enter the drier directly from the pulper, forming a layer about 4 in deep. The wet material passes on an endless conveyer, consisting of a drying belt of perforated sheet metal, through three zones of temperature. The hot-air current has a temperature of 250–260° F. in the first stage and 180–200° F. in the third. The dried cossettes, which are suitable for feeding to sheep and cattle, may be ground to potato meal for use in the rations of pigs.
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  • 32
    Publikationsdatum: 1939-04-01
    Beschreibung: 1. A study was made of nitrogen-fixation by Azotobacter chroococcum alone in a medium containing dextrose (which it can utilize) and in mixture with a coliform organism on a medium containing no carbohydrate except starch, which Azotobacter cannot utilize unless it be hydrolysed by the coliform organism or some other agency.2. The amount of nitrogen fixed in the mixed cultures was found to be maximal at two temperatures, and a discussion is given of the causes thought to be operative in producing the double maximum.
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  • 33
    Publikationsdatum: 1939-04-01
    Beschreibung: 1. The discrepancy between the results obtained by various workers concerning the inheritance of earliness or the time of ear emergence in cereals, suggests that this character needs further elucidation physiologically before genetic analysis can be properly undertaken.2. A study of the ear emergence characteristics of varieties when grown under varying conditions indicates that the expression of this character is very much affected by the growing conditions, and the physiological basis must be understood before the various expressions of earliness and lateness are appreciated. It is therefore suggested that the genetic analysis should be conducted in conjunction with a physiological analysis and with a proper consideration and understanding of the effect of environment.3. A series of crosses involving parental forms differing in time of ear emergence, and in some cases belonging to different physiological groups, has shown how differences in genetic behaviour can to some extent be correlated with the physiology of ear emergence of the parents.4. In one cross involving similar types, no evidence of segregation or large genetic difference was obtained. In two crosses involving larger differences of similar types, evidence for a single major factor difference was obtained. In other crosses between different physiological types, and an unstable form, more complex genetic results including transgressive inheritance were obtained. Still other crosses superficially suggested a 3: 1 ratio in the F2, but the presence of a certain amount of transgression, and the behaviour of the F3, pointed to a more complicated relationship.5. Two crosses involving different physiological types were studied in the F1 and the F2 when sown at different times in the spring by dividing the progenies into separate portions. It was shown that the behaviour of the F1 and the F2 of the same cross was materially affected by the sowing time.
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  • 34
    Publikationsdatum: 1939-04-01
    Beschreibung: 1. The post-weaning growth of 135 litters has been analysed with a view to determining the relationship of certain arbitrary subdivisions with each other. For this purpose, the weight increases during three periods of 28 days have been denned in two ways—first, by age, the periods being 10–14, 14–18, and 18–22 weeks, and secondly, by weight, the periods beginning at 40, 80 and 120 lb. and continuing as before for 4 weeks.2. When the periods are defined by age, the mean increase per pig per litter is affected by weaning weight, but not by litter size (Table III). The variability of the individual increases becomes greater as the pigs become older and heavier (that is, passing from one period to a later one), but less within a period as the rate of growth increases (Table IV). It was not affected by litter size.3. The distribution of individual weights became increasingly skew with age. This is regarded as a graphical illustration of the fact that while absolute rate of growth is increasing, initially small animals must fall farther and farther behind (Graph 3).4. The correlations between the average litter increases in different periods were calculated for litter sizes 6–11. In general, the coefficient for periods 1 and 2 was about 0·4, and for periods 2 and 3 about 0·6 (Table VI). This is interpreted to mean that, when judged by results over the whole time under observation, litters with a high correlation between the increases in weight during short periods are not properly comparable with those with a low correlation. By this method, differences in rate of growth having an important influence on carcass quality may be obscured.
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  • 35
    Publikationsdatum: 1939-10-01
    Beschreibung: X-ray, optical, dehydration and chemical methods in use for the identification of minerals in soil colloids are discussed with special regard to their limitations. These are mainly due to uncertainties about the variation of physical properties of standard minerals with decreasing grain size and the possible existence and importance of amorphous material. The aggregate method in X-ray analysis, which is specially important for soil colloids, is described. Various techniques for dehydration and optical analysis are discussed, and it is concluded that they are useful only when used in combination with X-ray data. The advantages of combining various chemical methods with X-ray analysis are pointed out.Standard data are given for a number of minerals, and the evidence for their occurrence in soil colloids is reviewed. These minerals are quartz, cristobalite, oxides and hydroxides of iron and aluminium, minerals of the kaolinite, montmorillonite and mica groups.
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  • 36
    Publikationsdatum: 1939-04-01
    Beschreibung: 1. An endeavour was made to obtain a blend of Tuscan wheat with a high quality line which would yield as much as Tuscan, at the same time possessing a superior baking quality. Of the eleven lines which were blended with Tuscan, nine blends returned yields corresponding to the expectation calculated from the pure varieties, and two blends yielded more than the expectation; these increases were not statistically significant.2. Tuscan, three lines and their blends were submitted to yield analytical treatment. The yield characters of the components of blends were compared with their yield characters when grown by themselves. Whilst the yields per plot of the blends corresponded to the expectation, the yield analyses revealed that the component varieties exerted a modifying influence on each other, which was different in each of the three trials. Tuscan demonstrated its aggressiveness by depressing in every case the yield characters of the lines with which it was blended.
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  • 37
    Publikationsdatum: 1939-04-01
    Beschreibung: Media from which phosphate was absent finally caused bronzing of the leaves of the resulting stunted plants of May King lettuce grown in sand culture, and red or crimson stalks. Phosphate alone produced characteristic purple (and/or bronze) and apple-green, flat, stunted rosettes with broad, non-crinkly leaves, and red stalks. Water alone caused stunted, straggly, purple plants, with relatively long, crimson stalks.Where some phosphate was supplied in addition to the other essential elements, a plant of normal colour resulted at first. Later, purple blotches appeared on the plants receiving inadequate supplies; the intensity of this purple became greater as the amount of phosphate in the medium diminished, and it could be controlled by varying the concentration of phosphate in the medium or the frequency of application. Another deficiency symptom was the tougher leaf resulting from a lack of phosphate. A sufficiency of phosphate caused earlier maturity.The media which contained the two greatest concentrations of phosphate were the best of those used because they gave the best growth, lettuces of the best colour without purple blotches, earlier maturity, and tenderer leaves.The final yields of heads were statistically the same with the two heaviest phosphate treatments, and both were greater by about 40% of the lesser yields than the two statistically equal yields with the lower amounts of phosphate. All the phosphate treatments gave yields superior by about 40,000–60,000% to the non-phosphate and phosphatealone yields, but this second difference had no commercial significance. Similar results were obtained for the roots, and for the dry weights of the tops and roots.
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  • 38
    Publikationsdatum: 1939-04-01
    Beschreibung: The majority of methods for determining carotene involve a preliminary determination of total carotenoids, followed by a phase separation of the two pigments. This phase separation considerably limits the usefulness of such methods, and in order to dispense with it a direct extraction of carotene is necessary. For this purpose petroleum ether may be used in the presence of alcohol.The use of hot alcoholic potash for the disintegration of leaf material and separation of chlorophyll leads to a very undesirable precipitate which hinders subsequent extraction. Two alternative methods are available, which overcome this difficulty, viz. (1) extraction with hot alcohol, followed by treatment of the extract with potash, and (2) saponification with hot aqueous potash, followed by filtration and extraction of the grass residue with alcohol. The second of these methods has been adopted, being of greater general utility and capable of producing complete cellular breakdown, which is essential for efficient extraction. Details of this extraction process have been described.A comparison of the results obtained, with those from two other methods, has been made by a colorimetric determination of the extracted pigment. The variance and standard error have been shown to be smaller than those for the other two methods, and it has been concluded that the results obtained are reproducible with considerable accuracy.
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  • 39
    Publikationsdatum: 1939-01-01
    Beschreibung: The influence of three feeding treatments of differing protein content on growth and carcass quality in bacon pigs has been investigated by the individual-feeding and group-feeding techniques. The protein supplement, which was used in conjunction with barley meal, weatings and a small allowance of lucerne meal, was composed of a mixture of ex. soya-bean meal, dried separated milk and feeding blood meal. Expressing, on the nitrogen basis, the amount of protein food in terms of its equivalent of white fish meal, the standard-protein treatment B supplied the equivalent of 9% of fish meal up to 90 lb. live weight, 7·6% from 90 to 150 lb. live weight and 3·8% from 150 to 200 lb. live weight. The corresponding figures for the low-protein treatment A were 4·5, 3·8 and 1·9%, and for the high-protein treatment C, 18, 15·2 and 7·6%.Considering the period of feeding up to 200 lb. live weight as a whole, it was found that differences of feeding treatment gave rise to no significant differences in respect of mean rate of live-weight increase and efficiency of food conversion (see Table VI). Only in the earliest stage of the feeding period did the pigs on the low-protein treatment A show a slightly, though significantly, lower rate of live-weight increase and poorer efficiency of food conversion than the pigs on treatments B and C, but such differences had ceased to be manifested by the time the pigs had arrived at 60 lb. live weight, and the slight initial disadvantage experienced by the low-protein pigs was wiped out during the later stages of the feeding period.
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  • 40
    Publikationsdatum: 1939-07-01
    Beschreibung: Experiments over six years on the use of different kinds and amounts of nitrogenous fertilizers on small plots of permanent pasture are described and summarized.Up to a level of 4·5 cwt. sulphate of ammonia per acre applied in February there was a proportionate response in dry matter production in April. Omitting the single year when scorching occurred, the average increase per cwt. of sulphate of ammonia applied was 2·3 cwt. dry matter with an additional 0·85 cwt. in the second (May) cut. The average recovery of the nitrogen applied in February was 35·9% in April, and 8·6% in May.With nitrogen applied in June the response in dry matter production in July and September–October was similar, but the recovery varied widely with the varying effect of nitrogen on clover production. With heavy depression of clover, percentage recovery was low or negative.On plots not receiving nitrogen the dry matter production for the whole year was at the rate of 1·92 cwt. per inch of rain reckoned on the harvest year (Oct.–Sept.). The largest variation from this was only 0·1 cwt.For the whole year the response to nitrogen was greatest in the years of lowest rainfall.The nitrogen applied in February considerably increased the protein in the “grasses” at the first cut, and to a small extent in the second cut. For the third and fourth cut it is suggested that the protein differences are correlated with differences in amounts of clover.For the first cut of the year “clovers” also show a much higher protein content on the nitrogen plots.
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  • 41
    Publikationsdatum: 1939-01-01
    Beschreibung: 1. Two experiments have been carried out on the Cambridge University Farm to test the desirability of including late-flowering red clover in the seeds mixture in the case of a 4-year ley, and to compare grazing with cutting for hay in the first harvest year.2. The majority of the red clover survived for the first 2 years, during which it increased the yield of dry matter very markedly; it did not lead to any reduction of yield in the last 2 years. By producing an early cover of the ground red clover checked the encroachment of weeds; although it reduced the proportion of wild white clover in the herbage in the later years, the reduction was not serious.3. Where the young plants were well established at the time, and normal weather conditions were experienced, grazing was definitely preferable to cutting for hay during the first harvest year. Where the plants were slow in establishing themselves, and in a superlatively dry spring and summer, grazing checked the development of the sward too much, and cutting for hay gave much better results.
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  • 42
    Publikationsdatum: 1939-01-01
    Beschreibung: Six litters of pigs farrowed, reared and fattened on a ration of barley meal, weatings, soya-bean meal, meat meal and minerals failed to thrive and in the later stages of fattening many of the pigs showed typical symptoms of vitamin A deficiency.Six comparable litters raised under similar conditions and on the same meal mixture with ° 1 or 2% of a commercial cod-liver oil of guaranteed purity and standardized vitamin content made good progress and nearly all the pigs weaned in these litters were fattened for pork or bacon.Estimations of liver reserves of vitamin A of the pigs receiving no cod-liver oil indicated that the liver store was exhausted soon after weaning. All pigs receiving cod-liver oil gradually increased their liver store of vitamin A. The stores rose approximately in proportion to the level fed and period of feeding. There was no evidence that the higher levels of cod-liver oil had any practical advantage over °%.The symptoms shown by the pigs receiving no cod-liver oil included loss of appetite, cessation of growth, impairment of vision in daylight, abnormal gait, convulsive fits and nervous collapse. Pneumonia and/or inflammation of the intestines was found in all of seven pigs that died during the fattening period.
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  • 43
    Publikationsdatum: 1939-07-01
    Beschreibung: The effect of rainfall, sowing date and yield on the percentage of nitrogen in the barley grain of certain representative plots on Hoosfield is studied.All these factors are shown to have marked effects. The farmyard manure plot differs from the others, both in mean percentage and in the effects of rainfall and yield.Changes in variety appear to have had little apparent influence, but there is a progressive decrease in the percentage of nitrogen which cannot be accounted for by changes in any of the above factors, and which may well be due to varietal improvementComparison is made with the results of the similar study on the permanent barley plots at Woburn.
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  • 44
    Publikationsdatum: 1939-04-01
    Beschreibung: An investigation into the effects of lime on five acid soils in north-east Scotland has been continued during the second and third years after the application of lime and also extended to two other centres.On four of the original soils the full effect of the lime on the surface soil has been largely maintained up to the end of the third year. The fifth, a soil of low base-exchange capacity, shows a considerable loss of lime by the end of the second year.The lime leached from the top nine inches of soil appears to be retained to only a slight extent in the second nine inches. This was particularly noticeable on a soil of low base-exchange capacity, where, during the two years after liming, the percentage saturation of the subsurface soil showed an increase from 64 to 67%, and the surface soil a decrease from 92 to 74%.The existence of a low liming factor (1·5), previously found to hold for a geologically basic soil, has been verified and found to apply also to a soil derived from slate.A fundamental property of the soils with a low liming factor is the high content of inorganic and organic fine material. Secondary characteristics that distinguish these soils from the others are the relatively high values for hygroscopicity and heat of wetting.
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  • 45
    Publikationsdatum: 1939-07-01
    Beschreibung: Experiments were made in 1936 and 1937 on barley plants grown in pot culture, to determine the effect of shading the ear or the shoot after ear emergence on dry weight and nitrogen content.It was found that after ear emergence the ear and the shoot (leaves and stem) make approximately equal contributions to the assimilation of the whole plant. In the 1936 experiment 28% of the final dry weight of the ear was accounted for by assimilation in the ear itself, and in the 1937 experiment, 19%. These are minimum estimates, for assimilation must have been proceeding in the ears during emergence, before the shading treatments were applied. The results agree well with similar estimates of the extent of assimilation in the ear made on wheat by other workers.The effects of shading on the amount of nitrogen present in the plant at harvest were somewhat variable, but they were always small compared with the effects on dry weight. Shading tended to reduce the amount of nitrogen in the ear, but as the dry weight of the ear was reduced to a much greater extent, - nitrogen as percentage of dry matter in the ear was increased. It is concluded from this result that translocation of nitrogen compounds to the ear is not closely dependent on the amount of the concurrent increase in dry weight of the ear. It appears that the approximate constancy of nitrogen percentage in the ear and the grain throughout development is a consequence of the particular conditions prevailing during normal growth in the field.The experiments showed that 20–30 % of the dry weight of the whole plant was added after ear emergence, suggesting that climatic conditions during this late stage of growth is of considerable importance in determining the final yield.The authors wish to thank Miss J. Hellyer for carrying out many of the determinations of nitrogen content, and Mr S. A. W. French for assistance with the statistical computation.
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  • 46
    Publikationsdatum: 1939-01-01
    Beschreibung: Analysing Hammond's data on the growth of limbs in the sheep, Huxley (1932) found a post-natal simple negative heterogony, or allometry, as in the latest terminology (Teissier, 1937), of the whole limb relative to the body. As lambs, and the young of most other grazing mammals, are born with relatively long limbs enabling them to follow their dams (Hammond, 1932), the same author pointed out that the leg must have exhibited positive allometry during foetal development.Having possession of a sufficient body of measurements on the skeletal development of female calves of the Chianina breed, a very tall beef and draft breed of cattle of Central Italy, I investigated the course of growth of height at withers relative to the growth of the length of the trunk (from shoulder to ischium). The growth of height at withers can be considered as a sufficiently reliable measure of the growth of forelimb length owing to the fact that the two principal angles in the limb (scapula-humerus and humerus-radius) do not change very much with age (Engeler, 1935).It was found that the growth of forelimb length in this breed of cattle exhibits a simple negative allometry relative to the growth of trunk length. This simple allometry, with growth constant about 0·78, holds from birth until over the age of 3 years, that is, throughout practically the whole post-natal growth.Lack of data after this age leaves open to further research the course in the ultimate period of development.I thought it would be of some interest to compare various breeds of cattle differing rather widely in the absolute values, as well as in the proportions of height at withers and trunk length at birth and in later life.
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  • 47
    Publikationsdatum: 1939-01-01
    Beschreibung: 1. The quality status of Danish and English Wiltshire bacon sides representative of the highest grades produced at the present time has been investigated by the use of carcass measurements. The data resulting provide “standards” for practical guidance in stock improvement work on bacon pigs, and for the evaluation of experimental treatments involving bacon quality.2. The variability of the respective characters has been compared by means of the coefficient of variation of each. The results indicate that while selection on a basis of “external characters” and of such internal characters, as are readily measurable, leads to marked uniformity in respect of these characters, it does not necessarily involve similar uniformity in respect of important “internal characters” which are not taken into account in either stock selection or commercial grading practices.3. External characters thus do not provide a reliable indication of the internal quality status of the bacon pig, and since it is the latter which largely governs the cutting value of the side, concentration upon addition to the former is desirable if still further improvement in the quality of the bacon pig is desired.4. Variability appears to be affected also by the rate of development of the character concerned; late developing characters in general tend to be more variable than early.5. The intimate association between nutrition and the rate of development of the various parts and tissues of the pig provides a method of control in addition to that of selection.
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  • 48
    Publikationsdatum: 1939-01-01
    Beschreibung: 1. Yields of plots estimated from the known weights of “perfect” beet (i.e. plants with no gaps in the ring immediately surrounding them) showed 18 × 9 in. to be the optimum spacing.2. Sugar analyses performed on individual “perfect” beet showed that very diminutive roots were low in sugar, but that in general sugar percentage decreased with increasing weight of root; the decrease was, however, slight and only amounted to unity for an increase of 1000 g. in weight of root.3. In a dry year the roots immediately surrounding a gap compensated to the extent of 80–89% for the missing plant: the allocation to the individual neighbours was approximately inversely proportional to the square of their distance from the site of the gap. In a wet year compensation was less complete, amounting to from 41 to 84% under various spacing treatments. In both years compensation was less complete in the case of tops than in the case of roots.4. Within classes of beet similar in regard to spacing treatment and gappiness there still remained considerable variation due to soil and to genetic heterogeneity.5. The genetic variability of commercial seed appears to be large, so that in sugar beet experiments it is very desirable that each plot should carry a considerable number of plants: in these experiments, assuming that all variations within ultimate classes were of genetic origin, 400 plants would have been necessary to reduce the plot error due to genetic variability to 2% of the mean.
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  • 49
    Publikationsdatum: 1939-01-01
    Beschreibung: 1. The distribution of the total weight of beet in small areas (2 yards by 1 yard) was examined and estimates made of the effects of missing beet on the final yield, and of the yield to be obtained with various percentage plants.2. The distribution of gaps over the field is found to be non-random. The percentage of gaps varies from block to block, but does not differ greatly between the spacings. Three methods were employed and gave consistent results.
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  • 50
    Publikationsdatum: 1939-04-01
    Beschreibung: It is shown that the permeability of a water-saturated sand or fine powder can be calculated with considerable accuracy, if the porosity and the specific surface are known. In particular, the Kozeny theory here discussed leads to a very useful relationship between permeability and porosity. It is shown that clays do not conform to the theory in its simple form, but that it may be modified to give a satisfactory representation of the data available. The physical grounds for this modified theory are discussed in some detail, and it is shown that, while it is open to criticism, it is at least in harmony with our present knowledge of clays.An important deduction which follows from the modified theory is that clays may have zero permeability at quite considerable porosities, e.g. at ∈ = 0·207 for a clay soil, and ∈ = 0·355 for a plastic clay.
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  • 51
    Publikationsdatum: 1939-01-01
    Beschreibung: 1. The results of three uniformity trials with a U4 cotton at Barberton are reported. Two of these trials, carried out in a dry year, gave yields in the region of 400 lb. seed cotton per acre; the third, in a wet year, yielded over 1100 lb. per acre.2. Results from the three experiments agreed closely in essential details regarding size and shape of plots.3. In all three cases the percentage standard error per plot decreased rapidly as the plot was lengthened, but tended to increase slightly as the width of the plot was increased.4. The standard error increased as the block size was increased by the addition of more plots, indicating the desirability of keeping the number of strains in a variety trial as low as possible.5. With plots of the same shape the smallest plots were the most efficient, while with plots of the same size the efficiency increased as the plot shape became longer and narrower.6. Two fertility contour maps are given, which illustrate a general patchiness in yield common to cotton crops in the Barberton district.7. Details of the types of plot used at Barberton are given, together with the reasons for their adoption.
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  • 52
    Publikationsdatum: 1939-01-01
    Beschreibung: After reviewing the possibility of soil deterioration in the Gezira and its dependence on change in the exchangeable bases in the soil we have given an account of field trials with soil improvers. Increased penetration of water, improved supply of nitrogen and higher yields were obtained, but the effects were not lasting. A part of the initial response is ascribed to the flocculating action of salts formed near the soil surface by interaction between soil and soil improver. With continued watering these salts are washed from the surface soil, but the applications of soil improver were insufficiently heavy and the leaching insufficiently thorough to effect any deep-seated change in the soil. Drainage experiments in which effluents were measured and analysed showed small changes in the right direction, but their main outcome has been strikingly to confirm the view that lateral movement of water through Gezira soil is so slight as to promise small hope of achieving any large-scale improvements by means of subsoil drainage. Analyses of saltbush have been made and showed that although these plants remove much sodium from the soil they can hardly be regarded as a practicable agent in soil improvement, since the amount of sodium in the soil is comparatively large. On the other hand, it appears that by including saltbush in rotation and by removing the crop from the land it is possible to guarantee that no progressive deterioration will occur in consequence of accumulation of sodium introduced in the irrigation water. Further analyses of irrigation water were made in this connexion and substantially confirmed Beam's earlier data.We do not yet know whether, under normal irrigation, the general tendency is for an accumulation of sodium or whether, on the contrary, salts are slowly being washed from the soil column (Greene & Peto, 1934). Until the nature and extent of chemical changes in the soil are accurately assessed it is impossible to say what annual expenditure on soil improvers, drainage, growing and disposal of saltbush is needed for maintenance of soil fertility. Further laboratory work should be directed to the detailed study of base exchange in Gezira soil and to observation of the physical characters on which permeability depends while, in the field, further experiments should be made in the use of soil improvers and drainage; information should also be sought as to the most convenient and least expensive way of including saltbush in the rotations best suited to different parts of the Gezira and as to the economic disposal of saltbush ash.
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    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
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  • 53
    Publikationsdatum: 1939-01-01
    Beschreibung: Since sugar beet was first introduced into this country many experiments have been conducted to determine the effects of spacing on yield: the general advice based on these experiments is that beet should be spaced as closely as working conditions permit. Davies (1931) carried out a series of experiments in the West Midlands, and came to the conclusion that yield was not related to the number of roots per acre, but was affected by their distribution. His work demonstrated that wide row distances could not be compensated by narrow spacing in the row. He found that yield increased as row distance decreased down to 16 in., but that singling distances of 4—10 in. produced no differences in yield of roots: the yield of green leaves, on the other hand, was increased as singling distance decreased, but was unaffected by row distance (Davies & Dudley, 1929). Although Davies' results would be generally accepted as a true expression of the general rule, many isolated spacing experiments fail to conform to them; it is possible that discrepancies in results, that undoubtedly occur, may be due to variations in the “plant” actually obtained in the experiments. Engledow et al. (1928), as a result of counts and weights taken on ordinary farm crops of sugar beet, concluded that uniformity of “plant” was a most important spacing factor affecting yield. In America Brewbaker & Deming (1935) have found yield to be related to percentage stand (correlation coefficients varying from +0·35 to +0·70), the regression between the two variables being approximately linear over the range studied. They also found that uniformity of “plant” was more important than spacing distances, either between or in the rows. Their work showed that single gaps had little effect on yield, because neighbouring beet compensated for them to the extent of 96·2%; serious loss of yield only occurred, therefore, with adjacent gaps. Pedersen (1933) studied the relationship between percentage of gaps and yield in a large number of Danish experiments with sugar beet and mangolds. In the case of sugar beet he found that the compensatory growth of neighbouring roots amounted to 76% for a single gap, and that the percentage compensation decreased as the size of gap (i.e. number of missing beet) increased. In an earlier paper (Pedersen, 1931) he had shown that under ordinary field conditions the distribution of gaps was approximately random.
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  • 54
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
    Beschreibung: The Polar Record, No. 17, January 1939Page 1, line 17. For February 5 read February 16.line 18. For six days read one month.[The date given for Bellinghausen's sighting of the Antarctic Continent was given from the “old style” calendar to which must be added eleven days to make it correspond with our Gregorian Calendar, the “new style”.]Page 2, line 17. For Berlinske read Berlingske.
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  • 55
    Publikationsdatum: 1939-07-01
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  • 56
    Publikationsdatum: 1939-07-01
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  • 57
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
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  • 58
    Publikationsdatum: 1939-07-01
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  • 59
    Publikationsdatum: 1939-07-01
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  • 60
    Publikationsdatum: 1939-07-01
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  • 61
    Publikationsdatum: 1939-07-01
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  • 62
    Publikationsdatum: 1939-07-01
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  • 63
    Publikationsdatum: 1939-07-01
    Beschreibung: Dog-driving methods are a subject on which no two people think alike, and whenever two or three men meet together in the Arctic, they form the basis for endless discussion and argument. We can remember many a good night's sleep lost when a visitor arrived apparently tired out, but with enough energy left to sit up all night arguing the relative merits of fan or centre trace, or something of that sort. For this reason we feel rather diffident in adding our opinions to those already published recently in The Polar Record. With regard to different equipment, harness, sledges and team formations—these are almost entirely a question of local conditions and, therefore, not really worth arguing about. For instance, in North-East Greenland, we used regularly fan, centre trace and tandem formations to suit differing snow conditions, etc., and each was, under the right conditions, definitely superior to the other two.
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  • 64
    Publikationsdatum: 1939-07-01
    Beschreibung: In order to safeguard the stock of whales in northern seas, special regulations for Svalbard have been proposed by the Norwegian Government. These regulations forbid both Norwegian and foreign subjects to use a land station for the taking and treatment of whales in Svalbard and Jan Mayen. They follow the international agreements of 1937 and 1938 which provide for the closing of the Northern Hemisphere for pelagic baleen whaling and restriction of the activity of land stations to six months of the year.
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  • 65
    Publikationsdatum: 1939-07-01
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  • 66
    Publikationsdatum: 1939-07-01
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  • 67
    Publikationsdatum: 1939-07-01
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  • 68
    Publikationsdatum: 1939-07-01
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  • 69
    Publikationsdatum: 1939-07-01
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  • 70
    Publikationsdatum: 1939-07-01
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  • 71
    Publikationsdatum: 1939-07-01
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  • 72
    Publikationsdatum: 1939-07-01
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  • 73
    Publikationsdatum: 1939-07-01
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  • 74
    Publikationsdatum: 1939-07-01
    Beschreibung: We read and hear so often of the harm done to primitive peoples by contact with European culture, that it is refreshing to find an exception to this rule. The Polar Eskimos of North-West Greenland were introduced to European culture through the visits of expeditions to that region, and there was no control of these until thirty years ago. Yet these Eskimos do not seem to have suffered any harm or to have lost their original independence. A journey to West Greenland is apt to be disappointing, because the original Eskimo race and culture has been greatly modified, but to visit Thule is to see the Eskimos of the story books, dressed in furs and eating literally almost nothing but meat and blubber, most of it raw.
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  • 75
    Publikationsdatum: 1939-07-01
    Beschreibung: Most of the major problems of Arctic geography have been solved, and there are now few stretches of coastline which have not been at least roughly mapped. In the Antarctic there are still huge blank spaces on the map, but even there the kind of rough and ready maps that were made by early explorers would now be scarcely adequate. A modern polar survey must be much more accurate and comprehensive if it is to be worth while and have any permanent value, and it therefore takes up rather more of the time which used to be almost entirely devoted to travel. On the other hand, modern inventions such as the light but accurate eyepiece reading theodolite, the camera, and the aeroplane, have made available very much more rapid methods of survey than were possible even twenty years ago.
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  • 76
    Publikationsdatum: 1939-07-01
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  • 77
    Publikationsdatum: 1939-07-01
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  • 78
    Publikationsdatum: 1939-07-01
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  • 79
    Publikationsdatum: 1939-07-01
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  • 80
    Publikationsdatum: 1939-07-01
    Beschreibung: It is one of the characteristics of the human body in health that an even warmth is maintained in its tissues and organs irrespective of the external environment. Whether an individual is undergoing active muscular exercise or is resting, body temperature as measured by the mouth is relatively constant, varying slightly in either direction from the temperature of 98.4° F. The maintenance of such a thermostatic control of body temperature depends on a balance between the heat produced within the body and the heat lost to its external environment by radiation to the surroundings, convection and conduction to the air, and the evaporation of moisture in the sweat from the surface of the skin, and to a lesser extent of water from the lungs.
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  • 81
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
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  • 82
    Publikationsdatum: 1939-07-01
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  • 83
    Publikationsdatum: 1939-07-01
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  • 84
    Publikationsdatum: 1939-07-01
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  • 85
    Publikationsdatum: 1939-07-01
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  • 86
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
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  • 87
    Publikationsdatum: 1939-07-01
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  • 88
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
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  • 89
    Publikationsdatum: 1939-07-01
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  • 90
    Publikationsdatum: 1939-07-01
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  • 91
    Publikationsdatum: 1939-07-01
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  • 92
    Publikationsdatum: 1939-07-01
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  • 93
    Publikationsdatum: 1939-07-01
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  • 94
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
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  • 95
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    Cambridge University Press
    Publikationsdatum: 1939-07-01
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  • 96
    Publikationsdatum: 1939-01-01
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  • 97
    Publikationsdatum: 1939-07-01
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  • 98
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    Cambridge University Press
    Publikationsdatum: 1939-01-01
    Beschreibung: The Polar Record, No. 16, July 1938Page 85, line 19. For Barentsberg mine 50,000 read Barentsberg mine 400,000.line 20. For Grumant mine 400,000 read Grumant mine 50,000.
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  • 99
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    Cambridge University Press
    Publikationsdatum: 1939-01-01
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  • 100
    Publikationsdatum: 1939-01-01
    Beschreibung: This Atlas is of interest to polar travellers since Soviet territory covers such a large section of the Arctic regions. We accordingly find that nearly every map of the territory goes well into the Arctic Circle. The two special pages of circumpolar maps are well printed and follow the usual convention for showing routes of expeditions. Insets on the Arctic sheet give a valuable map of Severnaya Zemlya with relief and soundings; there are also insets of parts of Novaya Zemlya, while weather charts and ice-drift charts complete the page.
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