Late Quaternary Variability of Arctic Sea Ice: Insights From Biomarker Proxy Records and Model Simulations

Science.gov (United States)

Stein, R. H.; Fahl, K.; Gierz, P.; Niessen, F.; Lohmann, G.

2017-12-01

Over the last about four decades, coinciding with global warming and atmospheric CO2increase, the extent and thickness of Arctic sea ice has decreased dramatically, a decrease much more rapid than predicted by climate models. The driving forces of this change are still not fully understood. In this context, detailed paleoclimatic records going back beyond the timescale of direct observations, i.e., high-resolution Holocene records but also records representing more distant warm periods, may help to to distinguish and quantify more precisely the natural and anthropogenic greenhouse gas forcing of global climate change and related sea ice decrease. Here, we concentrate on sea ice biomarker records representing the penultimate glacial/last interglacial (MIS 6/MIS 5e) and the Holocene time intervals. Our proxy records are compared with climate model simulations using a coupled atmosphere-ocean general circulation model (AOGCM). Based on our data, polynya-type sea ice conditions probably occurred off the major ice sheets along the northern Barents and East Siberian continental margins during late MIS 6. Furthermore, we demonstrate that even during MIS 5e, i.e., a time interval when the high latitudes have been significantly warmer than today, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Assuming a closed Bering Strait (no Pacific Water inflow) during early MIS 5, model simulations point to a significantly reduced sea ice cover in the central Arctic Ocean, a scenario that is however not supported by the proxy record and thus seems to be less realistic. Our Holocene biomarker proxy records from the Chukchi Sea indicate that main factors controlling the millennial Holocene variability in sea ice are probably changes in surface water and heat flow from the Pacific into the Arctic Ocean as well as the long-term decrease in summer insolation

Cretaceous honeycomb oysters (Pycnodonte vesicularis) as palaeoseasonality records: A multi-proxy study

Science.gov (United States)

de Winter, Niels J.; Vellekoop, Johan; Vorsselmans, Robin; Golreihan, Asefeh; Petersen, Sierra V.; Meyer, Kyle W.; Speijer, Robert P.; Claeys, Philippe

2017-04-01

trace element and stable isotope records allow discussion of the degree to which Pycnodonte shells record their palaeoenvironment and can be used to reconstruct past sea water conditions. Preliminary results indicate that stable isotope and trace element ratios in Pynodonte shells record different seasonally changing sea water conditions in the Maastrichtian and reconstructed temperatures are consistent with results from clumped isotope analysis on the same shells and TEX86 analysis on the surrounding rocks. This multi-proxy study sheds light on the shell structure of Pycnodonte oysters, their chemical signature and growth pattern and investigates the expression of palaeoenvironmental proxies in the pristine shell calcite of these bivalves. This investigation shows the potential of using fossil Pycnodonte bivalves as a new archive for palaeoclimate reconstruction on a seasonal scale over a wide range of palaeolatitudes from the Cretaceous until the Pleistocene. References Huyghe et al. (2015) J. Geol Soc 172.5: 576-587. Videt (2003) Diss. Université Rennes 1. Wisshak, et al. (2009) Deep-Sea Res Pt I 56.3: 374-407.

Do pelagic grazers benefit from sea ice? Insights from the Antarctic sea ice proxy IPSO25

Directory of Open Access Journals (Sweden)

K. Schmidt

2018-04-01

Full Text Available Sea ice affects primary production in polar regions in multiple ways. It can dampen water column productivity by reducing light or nutrient supply, provide a habitat for ice algae and condition the marginal ice zone (MIZ for phytoplankton blooms on its seasonal retreat. The relative importance of three different carbon sources (sea ice derived, sea ice conditioned, non-sea-ice associated for the polar food web is not well understood, partly due to the lack of methods that enable their unambiguous distinction. Here we analysed two highly branched isoprenoid (HBI biomarkers to trace sea-ice-derived and sea-ice-conditioned carbon in Antarctic krill (Euphausia superba and relate their concentrations to the grazers' body reserves, growth and recruitment. During our sampling in January–February 2003, the proxy for sea ice diatoms (a di-unsaturated HBI termed IPSO25, δ13C  =  −12.5 ± 3.3 ‰ occurred in open waters of the western Scotia Sea, where seasonal ice retreat was slow. In suspended matter from surface waters, IPSO25 was present at a few stations close to the ice edge, but in krill the marker was widespread. Even at stations that had been ice-free for several weeks, IPSO25 was found in krill stomachs, suggesting that they gathered the ice-derived algae from below the upper mixed layer. Peak abundances of the proxy for MIZ diatoms (a tri-unsaturated HBI termed HBI III, δ13C  =  −42.2 ± 2.4 ‰ occurred in regions of fast sea ice retreat and persistent salinity-driven stratification in the eastern Scotia Sea. Krill sampled in the area defined by the ice edge bloom likewise contained high amounts of HBI III. As indicators for the grazer's performance we used the mass–length ratio, size of digestive gland and growth rate for krill, and recruitment for the biomass-dominant calanoid copepods Calanoides acutus and Calanus propinquus. These indices consistently point to blooms in the MIZ as an important feeding

Do pelagic grazers benefit from sea ice? Insights from the Antarctic sea ice proxy IPSO25

Science.gov (United States)

Schmidt, Katrin; Brown, Thomas A.; Belt, Simon T.; Ireland, Louise C.; Taylor, Kyle W. R.; Thorpe, Sally E.; Ward, Peter; Atkinson, Angus

2018-04-01

Sea ice affects primary production in polar regions in multiple ways. It can dampen water column productivity by reducing light or nutrient supply, provide a habitat for ice algae and condition the marginal ice zone (MIZ) for phytoplankton blooms on its seasonal retreat. The relative importance of three different carbon sources (sea ice derived, sea ice conditioned, non-sea-ice associated) for the polar food web is not well understood, partly due to the lack of methods that enable their unambiguous distinction. Here we analysed two highly branched isoprenoid (HBI) biomarkers to trace sea-ice-derived and sea-ice-conditioned carbon in Antarctic krill (Euphausia superba) and relate their concentrations to the grazers' body reserves, growth and recruitment. During our sampling in January-February 2003, the proxy for sea ice diatoms (a di-unsaturated HBI termed IPSO25, δ13C = -12.5 ± 3.3 ‰) occurred in open waters of the western Scotia Sea, where seasonal ice retreat was slow. In suspended matter from surface waters, IPSO25 was present at a few stations close to the ice edge, but in krill the marker was widespread. Even at stations that had been ice-free for several weeks, IPSO25 was found in krill stomachs, suggesting that they gathered the ice-derived algae from below the upper mixed layer. Peak abundances of the proxy for MIZ diatoms (a tri-unsaturated HBI termed HBI III, δ13C = -42.2 ± 2.4 ‰) occurred in regions of fast sea ice retreat and persistent salinity-driven stratification in the eastern Scotia Sea. Krill sampled in the area defined by the ice edge bloom likewise contained high amounts of HBI III. As indicators for the grazer's performance we used the mass-length ratio, size of digestive gland and growth rate for krill, and recruitment for the biomass-dominant calanoid copepods Calanoides acutus and Calanus propinquus. These indices consistently point to blooms in the MIZ as an important feeding ground for pelagic grazers. Even though ice

A multi-attribute approach to choosing adaptation strategies: Application to sea-level rise

International Nuclear Information System (INIS)

Smith, A.E.; Chu, H.Q.

1994-01-01

Selecting good adaptation strategies in anticipation of climate change is gaining increasing attention as it becomes increasingly clear that much of the likely change is already committed, and could not be avoided even with aggressive and immediate emissions reductions. Adaptation decision making will place special requirements on regional and local planners in the US and other countries, especially developing countries. Approaches, tools, and guidance will be useful to assist in an effective response to the challenge. This paper describes the value of using a multi-attribute approach for evaluating adaptation strategies and its implementation as a decision-support software tool to help planners understand and execute this approach. The multi-attribute approach described here explicitly addresses the fact that many aspects of the decision cannot be easily quantified, that future conditions are highly uncertain, and that there are issues of equity, flexibility, and coordination that may be as important to the decision as costs and benefits. The approach suggested also avoids trying to collapse information on all of the attributes to a single metric. Such metrics can obliterate insights about the nature of the trade-offs that must be made in choosing among very dissimilar types of responses to the anticipated threat of climate change. Implementation of such an approach requires management of much information, and an ability to easily manipulate its presentation while seeking acceptable trade-offs. The Adaptation Strategy Evaluator (ASE) was developed under funding from the US Environmental Protection Agency to provide user-friendly, PC-based guidance through the major steps of a multi-attribute evaluation. The initial application of ASE, and the focus of this paper, is adaptation to sea level rise. However, the approach can be easily adapted to any multi-attribute choice problem, including the range of other adaptation planning needs

Error characterization for asynchronous computations: Proxy equation approach

Science.gov (United States)

Sallai, Gabriella; Mittal, Ankita; Girimaji, Sharath

2017-11-01

Numerical techniques for asynchronous fluid flow simulations are currently under development to enable efficient utilization of massively parallel computers. These numerical approaches attempt to accurately solve time evolution of transport equations using spatial information at different time levels. The truncation error of asynchronous methods can be divided into two parts: delay dependent (EA) or asynchronous error and delay independent (ES) or synchronous error. The focus of this study is a specific asynchronous error mitigation technique called proxy-equation approach. The aim of this study is to examine these errors as a function of the characteristic wavelength of the solution. Mitigation of asynchronous effects requires that the asynchronous error be smaller than synchronous truncation error. For a simple convection-diffusion equation, proxy-equation error analysis identifies critical initial wave-number, λc. At smaller wave numbers, synchronous error are larger than asynchronous errors. We examine various approaches to increase the value of λc in order to improve the range of applicability of proxy-equation approach.

Long chain diol index (LDI) as an organic-based sea surface temperature proxy in the Korean East Sea (NW Pacific)

Science.gov (United States)

Gal, Jong-Ku; Kim, Jung-Hyun; Kang, Su-Jin; Lee, Dong-Hun; Shin, Kyung-Hoon

2016-04-01

Long chain diol index (LDI) was introduced as an organic-based sea surface temperature (SST) proxy. LDI is expressed as the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols. There were a few studies which accessed the potential of LDI based on the culture, core top sediments, suspended particulate organic matters, and down-core sediments. However it is still unknown about the source of the diols and robustness as the SST proxy in the various marine environments. In the current study, we examined the applicability of the LDI in the East Sea of Korea where productivity and thus sedimentation rates are high. We will compare the LDI data with those of alkenone-based UK'37 by analyzing two multicores covering the last 100 year.

Reconstructing palaeo-environmental conditions in the Baltic: A multi-proxy comparison from IODP Site M0059 (Little Belt)

Science.gov (United States)

Kotthoff, Ulrich; Andrén, Thomas; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Stepanova, Anna; Cotterill, Carol

2015-04-01

Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and hence provides a unique opportunity to analyse past changes. IODP Expedition 347 recovered a unique set of long sediment cores from the Baltic Sea Basin which allow new high-resolution reconstructions. The application of existing and development of new proxies in such a setting is complicated, as environmental changes often occur on much faster time scales with much larger variations. Therefore, we present a comparison of commonly used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt. The age model for Site M0059 is based on 14C dating and biostratigraphic correlation with neighbouring terrestrial pollen records. The aim of our study is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations for specific proxies. Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as land/air-temperature proxies. By comparison with dinoflagellate cysts and green algae remains from the same samples, a direct land-sea comparison is provided. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets including specific information on seasonality, but pollen-based reconstructions for Northern Europe may be hampered by plant migration effects. Chironomid remains are used where possible as indicators for surface water

Evaluation of Organic Proxies for Quantifying Past Primary Productivity

Science.gov (United States)

Raja, M.; Rosell-Melé, A.; Galbraith, E.

2017-12-01

Ocean primary productivity is a key element of the marine carbon cycle. However, its quantitative reconstruction in the past relies on the use of biogeochemical models as the available proxy approaches are qualitative at best. Here, we present an approach that evaluates the use of phytoplanktonic biomarkers (i.e. chlorins and alkenones) as quantitative proxies to reconstruct past changes in marine productivity. We compare biomarkers contents in a global suite of core-top sediments to sea-surface chlorophyll-a abundance estimated by satellites over the last 20 years, and the results are compared to total organic carbon (TOC). We also assess satellite data and detect satellite limitations and biases due to the complexity of optical properties and the actual defined algorithms. Our findings show that sedimentary chlorins can be used to track total sea-surface chlorophyll-a abundance as an indicator for past primary productivity. However, degradation processes restrict the application of this proxy to concentrations below a threshold value (1µg/g). Below this threshold, chlorins are a useful tool to identify reducing conditions when used as part of a multiproxy approach to assess redox sedimentary conditions (e.g. using Re, U). This is based on the link between anoxic/disoxic conditions and the flux of organic matter from the sea-surface to the sediments. We also show that TOC is less accurate than chlorins for estimating sea-surface chlorophyll-a due to the contribution of terrigenous organic matter, and the different degradation pathways of all organic compounds that TOC includes. Alkenones concentration also relates to primary productivity, but they are constrained by different processes in different regions. In conclusion, as lons as specific constraints are taken into account, our study evaluates the use of chlorins and alkenones as quantitative proxies of past primary productivity, with more accuracy than by using TOC.

Sea surface temperature variations in the western Mediterranean Sea over the last 20 kyr: A dual-organic proxy (U

NARCIS (Netherlands)

Rodrigo-Gámiz, M.; Martínez-Ruiz, F.; Rampen, S.W.; Schouten, S.; Sinninghe Damsté, J.S.

2014-01-01

A high-resolution sea surface temperature (SST) reconstruction of the western Mediterranean was accomplished using two independent, algae-based molecular organic proxies, i.e., the U-37(K) index based on long-chain unsaturated ketones and the novel long-chain diol index (LDI) based on the relative

Water Isotope Proxy-Proxy and Proxy-Model Convergence for Late Pleistocene East Asian Monsoon Rainfall Reconstructions

Science.gov (United States)

Clemens, S. C.; Holbourn, A.; Kubota, Y.; Lee, K. E.; Liu, Z.; Chen, G.

2017-12-01

Confidence in reconstruction of East Asian paleomonsoon rainfall using precipitation isotope proxies is a matter of considerable debate, largely due to the lack of correlation between precipitation amount and isotopic composition in the present climate. We present four new, very highly resolved records spanning the past 300,000 years ( 200 year sample spacing) from IODP Site U1429 in the East China Sea. We demonstrate that all the orbital- and millennial-scale variance in the onshore Yangtze River Valley speleothem δ18O record1 is also embedded in the offshore Site U1429 seawater δ18O record (derived from the planktonic foraminifer Globigerinoides ruber and sea surface temperature reconstructions). Signal replication in these two independent terrestrial and marine archives, both controlled by the same monsoon system, uniquely identifies δ18O of precipitation as the primary driver of the precession-band variance in both records. This proxy-proxy convergence also eliminates a wide array of other drivers that have been called upon as potential contaminants to the precipitation δ18O signal recorded by these proxies. We compare East Asian precipitation isotope proxy records to precipitation amount from a CCSM3 transient climate model simulation of the past 300,000 years using realistic insolation, ice volume, greenhouse gasses, and sea level boundary conditions. This model-proxy comparison suggests that both Yangtze River Valley precipitation isotope proxies (seawater and speleothem δ18O) track changes in summer-monsoon rainfall amount at orbital time scales, as do precipitation isotope records from the Pearl River Valley2 (leaf wax δ2H) and Borneo3 (speleothem δ18O). Notably, these proxy records all have significantly different spectral structure indicating strongly regional rainfall patterns that are also consistent with model results. Transient, isotope-enabled model simulations will be necessary to more thoroughly evaluate these promising results, and to

Geophysical Imaging of Sea-level Proxies in Beach-Ridge Deposits

Science.gov (United States)

Nielsen, L.; Emerich Souza, P.; Meldgaard, A.; Bendixen, M.; Kroon, A.; Clemmensen, L. B.

2017-12-01

We show ground-penetrating radar (GPR) reflection data collected over modern and fossil beach deposits from different localities along coastlines in meso-tidal regimes of Greenland and micro-tidal regimes of Denmark. The acquired reflection GPR sections show several similar characteristics but also some differences. A similar characteristic is the presence of downlapping reflections, where the downlap point is interpreted to mark the transition from upper shoreface to beachface deposits and, thus, be a marker of a level close to or at sea-level at the time of deposition. Differences in grain size of the investigated beach ridge system result in different scattering characteristics of the acquired GPR data. These differences call for tailored, careful processing of the GPR data for optimal imaging of internal beach ridge architecture. We outline elements of the GPR data processing of particular importance for optimal imaging. Moreover, we discuss advantages and challenges related to using GPR-based proxies of sea-level as compared to other methods traditionally used for establishment of curves of past sea-level variation.

Climatic and anthropogenic controls on Mississippi River floods: a multi-proxy palaeoflood approach

Science.gov (United States)

Munoz, S. E.; Therrell, M. D.; Remo, J. W.; Giosan, L.; Donnelly, J. P.

2017-12-01

Over the last century, many of the world's major rivers have been modified for the purposes of flood mitigation, power generation, and commercial navigation. Engineering modifications to the Mississippi River system have altered the river's sediment budget and channel morphology, but the influence of these modifications on flood risk is debated. Detecting and attributing changes in river discharge is challenging because instrumental streamflow records are often too short to evaluate the range of natural hydrological variability prior to the establishment of flood mitigation infrastructure. Here we show that multi-decadal trends of flood risk on the lower Mississippi River are strongly modulated by dynamical modes of climate variability, particularly the El Niño-Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO), but that artificial channelization has greatly amplified flood magnitudes over the last century. Our results, based on a multi-proxy reconstruction of flood frequency and magnitude spanning the last five hundred years that combines sedimentary, tree-ring, and instrumental records, reveal that the magnitude of the 100-year flood has increased by 20% over the period of record, with 75% of this increase attributed to river engineering. We conclude that the interaction of human alterations to the Mississippi River system with dynamical modes of climate variability has elevated the current flood risk to levels that are unprecedented within the last five centuries.

Climate variability in the SW Indian Ocean from an 8000-yr long multi-proxy record in the Mauritian lowlands shows a middle to late Holocene shift from negative IOD-state to ENSO-state

NARCIS (Netherlands)

de Boer, E.J.; Tjallingii, R.; Vélez, M.I.; Rijsdijk, K.F.; Vlug, A.; Reichart, G.J.; Prendergast, A.L.; de Louw, P.G.B.; Vincent Florens, F.B.; Baider, C.; Hooghiemstra, H.

2014-01-01

A multi-proxy reconstruction of a sediment core from the Tatos basin in the Mauritian lowlands reveals a dynamic environmental history during the last 8000 years. Under influence of sea level rise, the basin progressed from a wetland to a shallow lake between 8000 and 2500 cal yr BP and it slowly

Climate variability in the SW Indian Ocean from an 8000-yr long multi-proxy record in the Mauritian lowlands shows a middle to late Holocene shift from negative IOD-state to ENSO-state

NARCIS (Netherlands)

De Boer, Erik J.; Tjallingii, Rik; Vélez, Maria I.; Rijsdijk, Kenneth F.; Vlug, Anouk; Reichart, Gert-Jan; Prendergast, Amy L.; de Louw, Perry G B; Florens, F. B Vincent; Baider, Cláudia; Hooghiemstra, Henry

2014-01-01

A multi-proxy reconstruction of a sediment core from the Tatos basin in the Mauritian lowlands reveals a dynamic environmental history during the last 8000 years. Under influence of sea level rise, the basin progressed from a wetland to a shallow lake between 8000 and 2500cal yr BP and it slowly

Holocene multi-proxy environmental reconstruction from lake Hakluytvatnet, Amsterdamøya Island, Svalbard (79.5°N)

Science.gov (United States)

Gjerde, Marthe; Bakke, Jostein; D'Andrea, William J.; Balascio, Nicholas L.; Bradley, Raymond S.; Vasskog, Kristian; Ólafsdóttir, Sædis; Røthe, Torgeir O.; Perren, Bianca B.; Hormes, Anne

2018-03-01

High resolution proxy records of past climate are sparse in the Arctic due to low organic production that restricts the use of radiocarbon dating and challenging logistics that make data collection difficult. Here, we present a new lake record from lake Hakluytvatnet at Amsterdamøya island (79.5°N), the northwesternmost island on Svalbard. Multi-proxy analyses of lake sediments in combination with geomorphological mapping reveal large environmental shifts that have taken place at Amsterdamøya during the Holocene. A robust chronology has been established for the lake sediment core through 28 AMS radiocarbon ages, and this gives an exceptionally well-constrained age control for a lake at this latitude. The Holocene was a period with large changes in the Hakluytvatnet catchment, and the onset of the Neoglacial (ca. 5 ka) marks the start of modern-day conditions in the catchment. The Neoglacial is characterized by fluctuations in the minerogenic input to the lake as well as internal productivity, and we suggest that these fluctuations are driven by atmospherically forced precipitation changes as well as sea ice extent modulating the amount of moisture that can reach Hakluytvatnet.

Marine proxy evidence linking decadal North Pacific and Atlantic climate

Energy Technology Data Exchange (ETDEWEB)

Hetzinger, S. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); Halfar, J. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Mecking, J.V.; Keenlyside, N.S. [Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); University of Bergen, Geophysical Institute and Bjerknes Centre for Climate Research, Bergen (Norway); Kronz, A. [University of Goettingen, Geowissenschaftliches Zentrum, Goettingen (Germany); Steneck, R.S. [University of Maine, Darling Marine Center, Walpole, ME (United States); Adey, W.H. [Smithsonian Institution, Department of Botany, Washington, DC (United States); Lebednik, P.A. [ARCADIS U.S. Inc., Walnut Creek, CA (United States)

2012-09-15

Decadal- to multidecadal variability in the extra-tropical North Pacific is evident in 20th century instrumental records and has significant impacts on Northern Hemisphere climate and marine ecosystems. Several studies have discussed a potential linkage between North Pacific and Atlantic climate on various time scales. On decadal time scales no relationship could be confirmed, potentially due to sparse instrumental observations before 1950. Proxy data are limited and no multi-centennial high-resolution marine geochemical proxy records are available from the subarctic North Pacific. Here we present an annually-resolved record (1818-1967) of Mg/Ca variations from a North Pacific/Bering Sea coralline alga that extends our knowledge in this region beyond available data. It shows for the first time a statistically significant link between decadal fluctuations in sea-level pressure in the North Pacific and North Atlantic. The record is a lagged proxy for decadal-scale variations of the Aleutian Low. It is significantly related to regional sea surface temperature and the North Atlantic Oscillation (NAO) index in late boreal winter on these time scales. Our data show that on decadal time scales a weaker Aleutian Low precedes a negative NAO by several years. This atmospheric link can explain the coherence of decadal North Pacific and Atlantic Multidecadal Variability, as suggested by earlier studies using climate models and limited instrumental data. (orig.)

Land-sea coupling of early Pleistocene glacial cycles in the southern North Sea exhibit dominant Northern Hemisphere forcing

NARCIS (Netherlands)

Donders, Timme; Van Helmond, Niels A.G.M.; Verreussel, Roel; Munsterman, Dirk; Veen, Johan Ten; Speijer, Robert P.; Weijers, Johan W.H.; Sangiorgi, Francesca; Peterse, Francien; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.; Lourens, Lucas; Kuhlmann, Gesa; Brinkhuis, Henk

2018-01-01

We assess the disputed phase relations between forcing and climatic response in the early Pleistocene with a spliced Gelasian (ĝ1/4 2.6-1.8ĝ€Ma) multi-proxy record from the southern North Sea basin. The cored sections couple climate evolution on both land and sea during the intensification of

Multi-proxy reconstructions and the power of integration across marine, terrestrial, and freshwater ecosystems. (Invited)

Science.gov (United States)

Black, B.

2013-12-01

Over the past decade, dendrochronology (tree-ring analysis) techniques have been increasingly applied to growth increments of various bivalve, fish, and coral species. In particular, the use of crossdating ensures that all increments in a dataset have assigned the correct calendar year of formation and that the resulting chronology is exactly placed in time. Such temporal alignment facilitates direct comparisons among chronologies that span diverse taxa and ecosystems, illustrating the pervasive, synchronizing influence of climate from alpine forests to the continental slope. Such an approach can be particularly beneficial to reconstructions in that each species captures climate signals from its unique 'perspective' of life history and habitat. For example, combinations of tree-ring data and chronologies for the long-lived bivalve Pacific geoduck (Panopea generosa) capture substantially more variance in regional sea surface temperatures than either proxy could explain alone. Just as importantly, networks of chronologies spanning multiple trophic levels can help identify climate variables critical to ecosystem functioning, which can then be targeted to generate most biologically relevant reconstructions possible. Along the west coast of North America, fish and bivalve chronologies in combination with records of seabird reproductive success indicate that winter sea-level pressure is closely associated with California Current productivity, which can be hind-cast over the past six centuries using coastal tree-ring chronologies. Thus, multiple proxies not only increase reconstruction skill, but also help isolate climate variables most closely linked to ecosystem structure and functioning.

Long-chain alkaenone unsaturation index as sea surface temperature proxy in southwest Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Sarma, N.S.; Pasha, S.K.G.; SriRamKrishna, M.; Shirodkar, P.V.; Yadava, M.G.; Rao, K.M.

As a proxy of the sea surface temperature (SST), C sub(37) long-chain alkenones (LCAs) preserved in sediments of the southwestern Bay of Bengal and dating back to the last glacial period, were identified in SIM GC-EI MS spectra run at m/z 530...

A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

NARCIS (Netherlands)

Morellón, M.; Pérez-Sanz, A.; Corella, J.P.; Büntgen, U.; Catalán, J.; González-Samprizé, P.; González-Trueba, J.J.; López-Sáez, J.A.; Moreno, A.; Pla-Rabes, S.; Saz-Sánchez, M.Á.; Scussolini, P.; Serrano, E.; Steinhilber, F.; Stefanova, V.; Vegas-Vilarrúbia, T.; Valero-Garcés, B.

2012-01-01

This paper reviews multi-proxy paleoclimatic reconstructions with robust age-control derived from lacustrine, dendrochronological and geomorphological records and characterizes the main environmental changes that occurred in the Southern Pyrenees during the last millennium. Warmer and relatively

Medieval Horse Stable; The Results of Multi Proxy Interdisciplinary Research

Science.gov (United States)

Dejmal, Miroslav; Lisá, Lenka; Fišáková Nývltová, Miriam; Bajer, Aleš; Petr, Libor; Kočár, Petr; Kočárová, Romana; Nejman, Ladislav; Rybníček, Michal; Sůvová, Zdenka; Culp, Randy; Vavrčík, Hanuš

2014-01-01

A multi proxy approach was applied in the reconstruction of the architecture of Medieval horse stable architecture, the maintenance practices associated with that structure as well as horse alimentation at the beginning of 13th century in Central Europe. Finally, an interpretation of the local vegetation structure along Morava River, Czech Republic is presented. The investigated stable experienced two construction phases. The infill was well preserved and its composition reflects maintenance practices. The uppermost part of the infill was composed of fresh stabling, which accumulated within a few months at the end of summer. Horses from different backgrounds were kept in the stable and this is reflected in the results of isotope analyses. Horses were fed meadow grasses as well as woody vegetation, millet, oat, and less commonly hemp, wheat and rye. Three possible explanations of stable usage are suggested. The stable was probably used on a temporary basis for horses of workers employed at the castle, courier horses and horses used in battle. PMID:24670874

Multi-decadal Arctic sea ice roughness.

Science.gov (United States)

Tsamados, M.; Stroeve, J.; Kharbouche, S.; Muller, J. P., , Prof; Nolin, A. W.; Petty, A.; Haas, C.; Girard-Ardhuin, F.; Landy, J.

2017-12-01

The transformation of Arctic sea ice from mainly perennial, multi-year ice to a seasonal, first-year ice is believed to have been accompanied by a reduction of the roughness of the ice cover surface. This smoothening effect has been shown to (i) modify the momentum and heat transfer between the atmosphere and ocean, (ii) to alter the ice thickness distribution which in turn controls the snow and melt pond repartition over the ice cover, and (iii) to bias airborne and satellite remote sensing measurements that depend on the scattering and reflective characteristics over the sea ice surface topography. We will review existing and novel remote sensing methodologies proposed to estimate sea ice roughness, ranging from airborne LIDAR measurement (ie Operation IceBridge), to backscatter coefficients from scatterometers (ASCAT, QUICKSCAT), to multi angle maging spectroradiometer (MISR), and to laser (Icesat) and radar altimeters (Envisat, Cryosat, Altika, Sentinel-3). We will show that by comparing and cross-calibrating these different products we can offer a consistent multi-mission, multi-decadal view of the declining sea ice roughness. Implications for sea ice physics, climate and remote sensing will also be discussed.

Attempt of absolute dating and reconstitutions of climate changes in the Caribbean Sea: multi-proxy approaches to planktonic foraminifera and fine aragonitic fraction

International Nuclear Information System (INIS)

Sepulcre, S.

2008-06-01

Absolute dating of climate archives is essential to better understand climate mechanisms. A marine sediment core from the Caribbean Sea enriched in fine-grained aragonite (suitable to U/Th dating) has been studied for both planktonic foraminifera tests (≥150 μm) and fine fraction (≤63 μm) over the last one million years using mineralogical and geochemical approaches. This study aims at i) examining lead/lag of δ 18 O and radiometric ages of the different-size fractions and ii) reconstructing paleo-environment in the area. The fine fraction mineralogy is strongly influenced by glacial-interglacial sea level changes. The offset of δ 18 O and 14 C ages between the fine and foraminifera fractions during Termination I is partly explained by a bioturbation model. Attempt of U/Th dating to Termination II and V reveals that the fine fraction contains non-radiogenic Th, which needs further analytical development. Reconstructed surface water δ 18 O changes suggest a decrease in surface water salinity at the end of Mid-Pleistocene Transition related to ITCZ position over the Caribbean Sea. (author)

Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea

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Fowell, Sara E.; Sandford, Kate; Stewart, Joseph A.; Castillo, Karl D.; Ries, Justin B.; Foster, Gavin L.

2016-10-01

Caribbean sea surface temperatures (SSTs) have increased at a rate of 0.2°C per decade since 1971, a rate double that of the mean global change. Recent investigations of the coral Siderastrea siderea on the Belize Mesoamerican Barrier Reef System (MBRS) have demonstrated that warming over the last 30 years has had a detrimental impact on calcification. Instrumental temperature records in this region are sparse, making it necessary to reconstruct longer SST records indirectly through geochemical temperature proxies. Here we investigate the skeletal Sr/Ca and Li/Mg ratios of S. siderea from two distinct reef zones (forereef and backreef) of the MBRS. Our field calibrations of S. siderea show that Li/Mg and Sr/Ca ratios are well correlated with temperature, although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef. These differences suggest that a secondary parameter also influences these SST proxies, highlighting the importance for site- and species-specific SST calibrations. Application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral, but well-matched reconstructed temperatures in forereef coral, both between Sr/Ca-SSTs and Li/Mg-SSTs, and in comparison to the Hadley Centre Sea Ice and Sea Surface Temperature record. Reconstructions generated from a combined Sr/Ca and Li/Mg multiproxy calibration improve the precision of these SST reconstructions. This result confirms that there are circumstances in which both Li/Mg and Sr/Ca are reliable as stand-alone and combined proxies of sea surface temperature. However, the results also highlight that high-precision, site-specific calibrations remain critical for reconstructing accurate SSTs from coral-based elemental proxies.

A comparative experimental approach to ecotoxicology in shallow-water and deep-sea holothurians suggests similar behavioural responses.

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Brown, Alastair; Wright, Roseanna; Mevenkamp, Lisa; Hauton, Chris

2017-10-01

Exploration of deep-sea mineral resources is burgeoning, raising concerns regarding ecotoxicological impacts on deep-sea fauna. Assessing toxicity in deep-sea species is technologically challenging, which promotes interest in establishing shallow-water ecotoxicological proxy species. However, the effects of temperature and hydrostatic pressure on toxicity, and how adaptation to deep-sea environmental conditions might moderate these effects, are unknown. To address these uncertainties we assessed behavioural and physiological (antioxidant enzyme activity) responses to exposure to copper-spiked artificial sediments in a laboratory experiment using a shallow-water holothurian (Holothuria forskali), and in an in situ experiment using a deep-sea holothurian (Amperima sp.). Both species demonstrated sustained avoidance behaviour, evading contact with contaminated artificial sediment. However, A. sp. demonstrated sustained avoidance of 5mgl -1 copper-contaminated artificial sediment whereas H. forskali demonstrated only temporary avoidance of 5mgl -1 copper-contaminated artificial sediment, suggesting that H. forskali may be more tolerant of metal exposure over 96h. Nonetheless, the acute behavioural response appears consistent between the shallow-water species and the deep-sea species, suggesting that H. forskali may be a suitable ecotoxicological proxy for A. sp. in acute (≤24h) exposures, which may be representative of deep-sea mining impacts. No antioxidant response was observed in either species, which was interpreted to be the consequence of avoiding copper exposure. Although these data suggest that shallow-water taxa may be suitable ecotoxicological proxies for deep-sea taxa, differences in methodological and analytical approaches, and in sex and reproductive stage of experimental subjects, require caution in assessing the suitability of H. forskali as an ecotoxicological proxy for A. sp. Nonetheless, avoidance behaviour may have bioenergetic consequences that

Correspondence of Mesozoic Eustatic Sea-Level Change with Palaeoclimate Proxies: Evidence for Glacio-Eustasy?

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Simmons, M.; Davies, A.; Gréselle, B.

2011-12-01

Large-scale changes in stratigraphic architecture and facies that are brought about by changes in relative sea-level have been the focus of much academic and industry study over the last few decades. The authors, plus numerous colleagues, have studied over 11,000 stratigraphic sections worldwide. By applying biostratigraphic and chemostratigraphic calibration in suitable locations from this dataset it is possible to demonstrate over 250 synchronous global sequence stratigraphic events in the Phanerozoic including over 100 in the Mesozoic. This then raises the question - what causes globally synchronous eustatic sea-level change? To answer this question requires an understanding of both the pace and amplitude of the observed eustatic sea-level change. In successions where duration can be deduced from orbital forcing cycles, our observed sea-level changes appear to be relatively rapid - less than 500,000 years, for example, for sea-level rises in the Late Jurassic. The amplitude of such rises is in the order of tens of metres. Such rates and amplitudes as inferred from our global model preclude tectonism as a primary driver and implicate glacio-eustacy as a key driving mechanism, even in supposed "greenhouse times". Given the clear economic importance of understanding the underlying mechanisms driving this eustatic change we have compiled records of key isotopic proxies through the entire Mesozoic in an effort to explore the relationship between global sea-level and palaeoclimate. Our research reveals a clear link between many large-scale maximum flooding events with known episodes of palaeoclimatic warming and between climatic cooling events and lowstand intervals, further implicating glacio-eustacy. In addition to the isotopic proxy evidence we have also compiled direct indicators for the occurrence of cold polar conditions, including the presence of ice sheets, in the Mesozoic (e.g. tillites, glendonites). This has been incorporated into plate tectonic

Nutrient regime and upwelling in the northern Benguela since the middle Holocene in a global context – a multi-proxy approach

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S. Meisel

2011-08-01

Full Text Available The last 5500 years of climate change and environmental response in the northern Benguela Coastal Upwelling are reconstructed by means of three sediment cores from the inner shelf off central Namibia. The study is based on nutrient (δ15N, δ13C and productivity proxies (accumulation rates of total organic carbon; ARTOC. Reconstructed sea surface temperatures (alkenone-derived SST and temperatures at subsurface depths (Tδ18O; based on tests of planktonic foraminifers reflect the physical boundary conditions. The selection of proxy indicators proved a valuable basis for robust palaeo-climatic reconstructions, with the resolution ranging from multi-decadal (NAM1 over centennial (core 178 to millennial scale (core 226620. The northern Benguela experienced pronounced and rapid perturbation during the middle and late Holocene, and apparently, not all are purely local in character. In fact, numerous correlations with records from the adjacent South African subcontinent and the northern hemisphere testify to global climatic teleconnections. The Holocene Hypsithermal, for instance, is just as evident as the Little Ice Age (LIA and the Roman Warm Period. The marked SST-rise associated with the latter is substantiated by other marine and terrestrial data from the South African realm. The LIA (at least its early stages manifests itself in intensified winds and upwelling, which accords with increased rainfall receipts above the continental interior. It appears that climate signals are transferred both via the atmosphere and ocean. The combined analysis of SST and Tδ18O proved a useful tool in order to differentiate between both pathways. SSTs are primarily controlled by the intensity of atmospheric circulation features, reflecting changes of upwelling-favourable winds. Tδ18O records the temperature of the source water and often correlates with global ocean conveyor speed due to varying inputs of warm Agulhas Water. It seems as though conveyor slowdown or

A nonlinear multi-proxy model based on manifold learning to reconstruct water temperature from high resolution trace element profiles in biogenic carbonates

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M. Bauwens

2010-11-01

Full Text Available A long standing problem in paleoceanography concerns the reconstruction of water temperature from δ¹⁸O carbonate. It is problematic in the case of freshwater influenced environments because the δ¹⁸O isotopic composition of the ambient water (related to salinity needs to be known. In this paper we argue for the use of a nonlinear multi-proxy method called Weight Determination by Manifold Regularization (WDMR to develop a temperature reconstruction model that is less sensitive to salinity variations. The motivation for using this type of model is twofold: firstly, observed nonlinear relations between specific proxies and water temperature motivate the use of nonlinear models. Secondly, the use of multi-proxy models enables salinity related variations of a given temperature proxy to be explained by salinity-related information carried by a separate proxy. Our findings confirm that Mg/Ca is a powerful paleothermometer and highlight that reconstruction performance based on this proxy is improved significantly by combining its information with the information for other trace elements in multi-proxy models. Although the models presented here are black-box models that do not use any prior knowledge about the proxies, the comparison of model reconstruction performances based on different proxy combinations do yield useful information about proxy characteristics. Using Mg/Ca, Sr/Ca, Ba/Ca and Pb/Ca the WDMR model enables a temperature reconstruction with a root mean squared error of ± 2.19 °C for a salinity range between 15 and 32.

Seemingly divergent sea surface temperature proxy records in the central Mediterranean during the last deglaciation

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M.-A. Sicre

2013-06-01

Full Text Available Sea surface temperatures (SSTs were reconstructed over the last 25 000 yr using alkenone paleothermometry and planktonic foraminifera assemblages from two cores of the central Mediterranean Sea: the MD04-2797 core (Siculo–Tunisian channel and the MD90-917 core (South Adriatic Sea. Comparison of the centennial scale structure of the two temperature signals during the last deglaciation period reveals significant differences in timing and amplitude. We suggest that seasonal changes likely account for seemingly proxy record divergences during abrupt transitions from glacial to interglacial climates and for the apparent short duration of the Younger Dryas (YD depicted by the alkenone time series, a feature that has already been stressed in earlier studies on the Mediterranean deglaciation.

Reconstructing Holocene palaeo-environmental conditions in the Baltic: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

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Kotthoff, Ulrich; Andrén, Elinor; Andrén, Thomas; Ash, Jeanine; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Slomp, Caroline; Stepanova, Anna; Warnock, Jonathan; van Helmond, Niels; Expedition 347 Science Party

2016-04-01

Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past against the background of climate changes. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and its sediment records provide a unique opportunity to analyse palaeo-environmental and climate change in central and northern Europe. IODP Expedition 347 recovered an exceptional set of sediment cores from the Baltic Sea which allow high-resolution reconstructions in unprecedented quality. We present a comparison of commonly-used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt over the past ˜8000 years. Our aim is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations of individual proxies. The age model for Site M0059 is based on 14Cdating, biostratigraphic correlation with neighbouring terrestrial pollen records, and sediment stratigraphy. Sedimentary organic carbon content and the bulk elemental composition have been measured, and can be used to determine the depositional environment and degree of oxygen depletion (e.g., Mo, Corg/Ptot). Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as a land/air-temperature proxy. Comparison with dinoflagellate cysts, insect remains, and green algae remains from the same samples provides a direct land-sea comparison. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets, including specific information on

A New Quantum Proxy Multi-signature Scheme Using Maximally Entangled Seven-Qubit States

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Cao, Hai-Jing; Zhang, Jia-Fu; Liu, Jian; Li, Zeng-You

2016-02-01

In this paper, we propose a new secure quantum proxy multi-signature scheme using seven-qubit entangled quantum state as quantum channels, which may have applications in e-payment system, e-government, e-business, etc. This scheme is based on controlled quantum teleportation. The scheme uses the physical characteristics of quantum mechanics to guarantee its anonymity, verifiability, traceability, unforgetability and undeniability.

A Mid-Holocene Relative Sea-Level Stack, New Jersey, USA

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Horton, B.; Walker, J. S.; Kemp, A.; Shaw, T. J.; Kopp, R. E.

2017-12-01

Most high resolution (decimeter- and decadal-scale) relative sea-level (RSL) records using salt-marsh microfossils as a proxy only extend through the Common Era, limiting our understanding of driving mechanisms of RSL change and how sea-level is influenced by changing climate. Records beyond the Common Era are limited by the depth of continuous sequences of salt-marsh peat suitable for high resolution reconstructions, as well as contamination by local processes such as sediment compaction. In contrast, sequences of basal peats have produced compaction-free RSL records through the Holocene, but at a low resolution (meter- and centennial-scale). We devise a new Multi-Proxy Presence/Absence Method (MP2AM) to develop a mid-Holocene RSL stack. We stack a series of 1 m basal peat cores that overlap along a uniform elevational gradient above an incompressible basal sand. We analyzed three sea-level indicators from 14 cores: foraminifera, testate amoebae, and stable carbon isotope geochemistry. To reconstruct RSL, this multi-proxy approach uses the timesaving presence/absence of forams and testates to determine the elevation of the highest occurrence of forams and the lowest occurrence of testates in each basal core. We use stable carbon isotope geochemistry to determine the C3/C4 vegetation boundary in each core. We develop age-depth models for each core using a series of radiocarbon dates. The RSL records from each 1 m basal core are combined to create a stack or, in effect, one long core of salt-marsh material. This method removes the issue of compaction to create a continuous RSL record to address temporal changes and periods of climate and sea-level variability. We reconstruct a southern NJ mid-Holocene RSL record from Edwin B. Forsythe National Wildlife Refuge, where Kemp et al. (2013) completed a 2500 yr RSL record using a foraminifera-based transfer function approach. Preliminary radiocarbon dates suggest the basal sequence is at least 4246-4408 cal yrs BP

Changes in sea ice cover and ice sheet extent at the Yermak Plateau during the last 160 ka - Reconstructions from biomarker records

Science.gov (United States)

Kremer, A.; Stein, R.; Fahl, K.; Ji, Z.; Yang, Z.; Wiers, S.; Matthiessen, J.; Forwick, M.; Löwemark, L.; O'Regan, M.; Chen, J.; Snowball, I.

2018-02-01

The Yermak Plateau is located north of Svalbard at the entrance to the Arctic Ocean, i.e. in an area highly sensitive to climate change. A multi proxy approach was carried out on Core PS92/039-2 to study glacial-interglacial environmental changes at the northern Barents Sea margin during the last 160 ka. The main emphasis was on the reconstruction of sea ice cover, based on the sea ice proxy IP25 and the related phytoplankton - sea ice index PIP25. Sea ice was present most of the time but showed significant temporal variability decisively affected by movements of the Svalbard Barents Sea Ice Sheet. For the first time, we prove the occurrence of seasonal sea ice at the eastern Yermak Plateau during glacial intervals, probably steered by a major northward advance of the ice sheet and the formation of a coastal polynya in front of it. Maximum accumulation of terrigenous organic carbon, IP25 and the phytoplankton biomarkers (brassicasterol, dinosterol, HBI III) can be correlated to distinct deglaciation events. More severe, but variable sea ice cover prevailed at the Yermak Plateau during interglacials. The general proximity to the sea ice margin is further indicated by biomarker (GDGT) - based sea surface temperatures below 2.5 °C.

Biogeochemical Cycling and Sea Ice Dynamics in the Bering Sea across the Mid-Pleistocene Transition

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Detlef, H.; Sosdian, S. M.; Belt, S. T.; Smik, L.; Lear, C. H.; Hall, I. R.; Kender, S.; Leng, M. J.; Husum, K.; Cabedo-Sanz, P.

2017-12-01

Today the Bering Sea is characterized by high primary productivity (PP) along the eastern shelf, maintained by CO2 and nutrient rich upwelled deep waters and nutrient release during spring sea ice melting. As such, low oxygen concentrations are pervasive in mid-depth waters. Changes in ventilation and export productivity in the past have been shown to impact this oxygen minimum zone. On glacial/interglacial (G/IG) timescales sea ice formation plays a pivotal role on intermediate water ventilation with evidence pointing to the formation of North Pacific Intermediate Water (NPIW) in the Bering Sea during Pleistocene glacial intervals. In addition, sea ice plays a significant role in both long- and short-term climate change via associated feedback mechanisms. Thus, records of sea ice dynamics and biogeochemical cycling in the Bering Sea are necessary to fully understand the interaction between PP, circulation patterns, and past G/IG climates with potential implications for the North Pacific carbon cycle. Here we use a multi-proxy approach to study sea ice dynamics and bottom water oxygenation, across three intervals prior to, across, and after the Mid-Pleistocene Transition (MPT, 1.2-0.7 Ma) from International Ocean Discovery Program Site U1343. The MPT, most likely driven by internal climate mechanisms, is ideal to study changes in sea ice dynamics and sedimentary redox conditions on orbital timescales and to investigate the implications for associated feedback mechanisms. The sea ice record, based on various biomarkers, including IP25, shows substantial increase in sea ice extent across the MPT and the occurrence of a late-glacial/deglacial sea ice spike, with consequences for glacial NPIW formation and land glacier retreat via the temperature-precipitation feedback. U/Mn of foraminiferal authigenic coatings, a novel proxy for bottom water oxygenation, also shows distinct variability on G/IG timescales across the MPT, most likely a result of PP and water mass

Age accuracy and resolution of Quaternary corals used as proxies for sea level

Science.gov (United States)

Edinger, E. N.; Burr, G. S.; Pandolfi, J. M.; Ortiz, J. C.

2007-01-01

The accuracy of global eustatic sea level curves measured from raised Quaternary reefs, using radiometric ages of corals at known heights, may be limited by time-averaging, which affects the variation in coral age at a given height. Time-averaging was assessed in uplifted Holocene reef sequences from the Huon Peninsula, Papua New Guinea, using radiocarbon dating of coral skeletons in both horizontal transects and vertical sequences. Calibrated 2σ age ranges varied from 800 to 1060 years along horizontal transects, but weighted mean ages calculated from 15-18 dates per horizon were accurate to a resolution within 154-214 yr. Approximately 40% of the variability in age estimate resulted from internal variability inherent to 14C estimates, and 60% was due to time-averaging. The accuracy of age estimates of sea level change in studies using single dated corals as proxies for sea level is probably within 1000 yr of actual age, but can be resolved to ≤ 250 yr if supported by dates from analysis of a statistical population of corals at each stratigraphic interval. The range of time-averaging among reef corals was much less than that for shelly benthos. Ecological time-averaging dominated over sedimentological time averaging for reef corals, opposite to patterns reported from shelly benthos in siliciclastic environments.

A Multi-Proxy Paradigm in the Pursuit of Ocean Paleoredox

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Anbar, A. D.; Duan, Y.; Kendall, B.; Reinhard, C.; Severmann, S.; Lyons, T. W.

2011-12-01

Mo isotope systematics from such sources. By considering sedimentary Fe enrichments together with Fe isotopes, we find that the Mo enrichment correlates with the telltale signature of a shelf-to-basin Fe redox "shuttle". Uranium isotopes also exhibit variations indicative of redox transformations. This multi-proxy dataset therefore paints a robust picture of trace metal redox cycling consistent with the "whiff" interpretation.

Arctic and Antarctic Oscillation signatures in tropical coral proxies over the South China Sea

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D.-Y. Gong

2009-05-01

Full Text Available Arctic Oscillation (AO and Antarctic Oscillation (AAO are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr content, which represents the sea surface temperature (SST. Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1–3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes.

A multi-archive coherent chronology: from Greenland to the Mediterranean sea

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Bazin, Lucie; Landais, Amaelle; Lemieux-Dudon, Bénédicte; Siani, Giuseppe; Michel, Elisabeth; Combourieu-Nebout, Nathalie; Blamart, Dominique; Genty, Dominique

2015-04-01

. & Wolff, E., An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012): 120-800 ka,Clim. Past 9, 1715-1731, 2013. Genty, D., Blamart, D., Ghaleb B., Plagnes, V., Causse, Ch., Bakalowicz, M., Zouari, K., Chkir, N., Hellstrom, J., Wainer, K., Bourges, F., Timing and dynamics of the last deglaciation from European and North African δ13C stalagmite profiles - comparison with Chinese ans South Hemisphere stalagmites, Quat. Sci. Rev. 25, 2118-2142, 2006. Lemieux-Dudon, B. ; Blayo, E. ; Petit, J.-R. ; Waelbroeck, C. ;Svensson, A. ; Ritz, C. ; Barnola, J.-M. ; Narcisi, B.M. ; Parrenin, F., Consitent dating for Antarctic and Greenland ice cores, Quat. Sci. Rev. 29(1-2), 2010. Veres, D. ; Bazin, L. ; Landais, A. ; Lemieux-Dudon, B. ; Parrenin, F. ; Martinerie, P. ; Toyé Mahamadou Kele, H. ; Capron, E. ; Chappellaz, J. ; Rasmussen, S. ; Severi, M. ; Svensson, A. ; Vinther, B. & Wolff, E., The Antarctic ice core chronology (AICC2012): an optimized multi-parameter and multi-site dating approach for the last 120 thousand years, Clim. Past, 9, 1733-1748, 2013.

Psychological Needs, Engagement, and Work Intentions: A Bayesian Multi-Measurement Mediation Approach and Implications for HRD

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Shuck, Brad; Zigarmi, Drea; Owen, Jesse

2015-01-01

Purpose: The purpose of this study was to empirically examine the utility of self-determination theory (SDT) within the engagement-performance linkage. Design/methodology/approach: Bayesian multi-measurement mediation modeling was used to estimate the relation between SDT, engagement and a proxy measure of performance (e.g. work intentions) (N =…

Satellite Altimeters and Gravimeters as Proxy of the Indonesian Throughflow

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Susanto, R. D.; Song, Y. T.

2014-12-01

The Indonesian Throughflow (ITF), the only pathway for interocean exchange between the Pacific to the Indian Ocean, plays an important role in global ocean circulation and climate. Yet, continuous ITF measurement is difficult and expensive. We demonstrate a plausible approach to derive the ITF transport proxy using satellite altimetry sea surface height (SSH), gravimetry ocean bottom pressure (OBP) data, in situ measurements from the Makassar Strait from 1996-1998 and 2004-2009, and a theoretical formulation. We first identified the optimal locations in the Pacific and Indian Ocean based on the optimal correlation between the ITF transport through the Makassar Strait and the pressure gradients, represented by the SSH and OBP differences between the Pacific and Indian Oceans at a 1° x 1° horizontal resolution. These geographical locations (centred at off-equatorial in the western Pacific Ocean and centred at along the equator in the eastern Indian Ocean) that control the strength and variability of the ITF transport in the Makassar Strait differ from early studies. The proxy time series follow the observation time series quite well, resolving the intraseasonal, monsoonal, and interannual signals with the 1993-2011 annual mean proxy transport of 11.6 ± 3.2 Sv. Our formulation provides a continuous approach to derive the ITF proxy as long as the satellite data are available. Such a continuous record would be difficult to achieve by in situ measurements alone due to logistical and financial challenges. Ideally, the proxy can be used to complement or fill in the gaps of the observations for a continuous ITF proxy for better understanding the ocean climate and validating ocean circulation models.

Holocene climate changes in eastern Beringia (NW North America) – A systematic review of multi-proxy evidence

Science.gov (United States)

Kaufman, Darrell S.; Axford, Yarrow L.; Henderson, Andrew C.G.; McKay, Nicolas P.; Oswald, W. Wyatt; Saenger, Casey; Anderson, R. Scott; Bailey, Hannah L.; Clegg, Benjamin; Gajewski, Konrad; Hu, Feng Sheng; Jones, Miriam C.; Massa, Charly; Routson, Cody C.; Werner, Al; Wooller, Matthew J.; Yu, Zicheng

2016-01-01

Reconstructing climates of the past relies on a variety of evidence from a large number of sites to capture the varied features of climate and the spatial heterogeneity of climate change. This review summarizes available information from diverse Holocene paleoenvironmental records across eastern Beringia (Alaska, westernmost Canada and adjacent seas), and it quantifies the primary trends of temperature- and moisture-sensitive records based in part on midges, pollen, and biogeochemical indicators (compiled in the recently published Arctic Holocene database, and updated here to v2.1). The composite time series from these proxy records are compared with new summaries of mountain-glacier and lake-level fluctuations, terrestrial water-isotope records, sea-ice and sea-surface-temperature analyses, and peatland and thaw-lake initiation frequencies to clarify multi-centennial- to millennial-scale trends in Holocene climate change. To focus the synthesis, the paleo data are used to frame specific questions that can be addressed with simulations by Earth system models to investigate the causes and dynamics of past and future climate change. This systematic review shows that, during the early Holocene (11.7–8.2 ka; 1 ka = 1000 cal yr BP), rather than a prominent thermal maximum as suggested previously, temperatures were highly variable, at times both higher and lower than present (approximate mid-20th-century average), with no clear spatial pattern. Composited pollen, midge and other proxy records average out the variability and show the overall lowest summer and mean-annual temperatures across the study region during the earliest Holocene, followed by warming over the early Holocene. The sparse data available on early Holocene glaciation show that glaciers in southern Alaska were as extensive then as they were during the late Holocene. Early Holocene lake levels were low in interior Alaska, but moisture indicators show pronounced differences across the region. The highest

Depression and suicidal behavior in adolescents: a multi-informant and multi-methods approach to diagnostic classification.

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Andrew James Lewis

2014-07-01

Full Text Available Background: Informant discrepancies have been reported between parent and adolescent measures of depressive disorders and suicidality. We aimed to examine the concordance between adolescent and parent ratings of depressive disorder using both clinical interview and questionnaire measures and assess multi-informant and multi-method approaches to classification.Method: Within the context of assessment of eligibility for a randomized clinical trial, 50 parent–adolescent pairs (mean age of adolescents = 15.0 years were interviewed separately with a structured diagnostic interview for depression, the KID-SCID. Adolescent self-report and parent-report versions of the Strengths and Difficulties Questionnaire, the Short Mood and Feelings Questionnaire and the Depressive Experiences Questionnaire were also administered. We examined the diagnostic concordance rates of the parent vs. adolescent structured interview methods and the prediction of adolescent diagnosis via questionnaire methods.Results: Parent proxy reporting of adolescent depression and suicidal thoughts and behavior is not strongly concordant with adolescent report. Adolescent self-reported symptoms on depression scales provide a more accurate report of diagnosable adolescent depression than parent proxy reports of adolescent depressive symptoms. Adolescent self-report measures can be combined to improve the accuracy of classification. Parents tend to over report their adolescent’s depressive symptoms while under reporting their suicidal thoughts and behavior.Conclusion: Parent proxy report is clearly less reliable than the adolescent’s own report of their symptoms and subjective experiences, and could be considered inaccurate for research purposes. While parent report would still be sought clinically where an adolescent refuses to provide information, our findings suggest that parent reporting of adolescent suicidality should be interpreted with caution.

Multi-proxy evidence of long-term changes in ecosystem structure in a Danish marine estuary, linked to increased nutrient loading

DEFF Research Database (Denmark)

Ellegaard, Marianne; Clarke, A.L.; Reuss, Nina Steenberg

2006-01-01

and prompting debate on the causes. This paper reports a multi-proxy survey of 210Pb-dated sediment cores from the anoxic basin. Analyses of diatoms, dinoflagellates, pigments and geochemical proxies were used to determine changes in ecosystem structure over the past 100 years. The aim was to establish ‘base......-line conditions', for management purposes, of the biological structure prior to 1900, and to examine possible causes of changes observed. Geochemical proxies total nitrogen (TN), total carbon (TC) and biogenic silica (BSi) were consistently high throughout the sediment record. Increased concentrations of pigments...... and natural isotopes (d13C, d15N) suggested increasing production and nutrient loading. The main changes in the biological proxies occurred between 1915 and the 1940s, and indicated that the estuary has been somewhat eutrophic since 1900, but that the eutrophication process increased over the past 100 years...

The exposure of Sydney (Australia) to earthquake-generated tsunamis, storms and sea level rise: a probabilistic multi-hazard approach.

Science.gov (United States)

Dall'Osso, F; Dominey-Howes, D; Moore, C; Summerhayes, S; Withycombe, G

2014-12-10

Approximately 85% of Australia's population live along the coastal fringe, an area with high exposure to extreme inundations such as tsunamis. However, to date, no Probabilistic Tsunami Hazard Assessments (PTHA) that include inundation have been published for Australia. This limits the development of appropriate risk reduction measures by decision and policy makers. We describe our PTHA undertaken for the Sydney metropolitan area. Using the NOAA NCTR model MOST (Method for Splitting Tsunamis), we simulate 36 earthquake-generated tsunamis with annual probabilities of 1:100, 1:1,000 and 1:10,000, occurring under present and future predicted sea level conditions. For each tsunami scenario we generate a high-resolution inundation map of the maximum water level and flow velocity, and we calculate the exposure of buildings and critical infrastructure. Results indicate that exposure to earthquake-generated tsunamis is relatively low for present events, but increases significantly with higher sea level conditions. The probabilistic approach allowed us to undertake a comparison with an existing storm surge hazard assessment. Interestingly, the exposure to all the simulated tsunamis is significantly lower than that for the 1:100 storm surge scenarios, under the same initial sea level conditions. The results have significant implications for multi-risk and emergency management in Sydney.

Towards uncertainty estimation for operational forecast products - a multi-model-ensemble approach for the North Sea and the Baltic Sea

Science.gov (United States)

Golbeck, Inga; Li, Xin; Janssen, Frank

2014-05-01

Several independent operational ocean models provide forecasts of the ocean state (e.g. sea level, temperature, salinity and ice cover) in the North Sea and the Baltic Sea on a daily basis. These forecasts are the primary source of information for a variety of information and emergency response systems used e.g. to issue sea level warnings or carry out oil drift forecast. The forecasts are of course highly valuable as such, but often suffer from a lack of information on their uncertainty. With the aim of augmenting the existing operational ocean forecasts in the North Sea and the Baltic Sea by a measure of uncertainty a multi-model-ensemble (MME) system for sea surface temperature (SST), sea surface salinity (SSS) and water transports has been set up in the framework of the MyOcean-2 project. Members of MyOcean-2, the NOOS² and HIROMB/BOOS³ communities provide 48h-forecasts serving as inputs. Different variables are processed separately due to their different physical characteristics. Based on the so far collected daily MME products of SST and SSS, a statistical method, Empirical Orthogonal Function (EOF) analysis is applied to assess their spatial and temporal variability. For sea surface currents, progressive vector diagrams at specific points are consulted to estimate the performance of the circulation models especially in hydrodynamic important areas, e.g. inflow/outflow of the Baltic Sea, Norwegian trench and English Channel. For further versions of the MME system, it is planned to extend the MME to other variables like e.g. sea level, ocean currents or ice cover based on the needs of the model providers and their customers. It is also planned to include in-situ data to augment the uncertainty information and for validation purposes. Additionally, weighting methods will be implemented into the MME system to develop more complex uncertainty measures. The methodology used to create the MME will be outlined and different ensemble products will be presented. In

Managing for No Net Loss of Ecological Services: An Approach for Quantifying Loss of Coastal Wetlands due to Sea Level Rise.

Science.gov (United States)

Kassakian, Jennifer; Jones, Ann; Martinich, Jeremy; Hudgens, Daniel

2017-05-01

Sea level rise has the potential to substantially alter the extent and nature of coastal wetlands and the critical ecological services they provide. In making choices about how to respond to rising sea level, planners are challenged with weighing easily quantified risks (e.g., loss of property value due to inundation) against those that are more difficult to quantify (e.g., loss of primary production or carbon sequestration services provided by wetlands due to inundation). Our goal was to develop a cost-effective, appropriately-scaled, model-based approach that allows planners to predict, under various sea level rise and response scenarios, the economic cost of wetland loss-with the estimates proxied by the costs of future restoration required to maintain the existing level of wetland habitat services. Our approach applies the Sea Level Affecting Marshes Model to predict changes in wetland habitats over the next century, and then applies Habitat Equivalency Analysis to predict the cost of restoration projects required to maintain ecological services at their present, pre-sea level rise level. We demonstrate the application of this approach in the Delaware Bay estuary and in the Indian River Lagoon (Florida), and discuss how this approach can support future coastal decision-making.

Planktonic Foraminifera Proxies Calibration Off the NW Iberian Margin: Nutrients Approach

Science.gov (United States)

Salgueiro, E.; Castro, C. G.; Zuniga, D.; Martin, P. A.; Groeneveld, J.; de la Granda, F.; Villaceiros-Robineau, N.; Alonso-Perez, F.; Alberto, A.; Rodrigues, T.; Rufino, M. M.; Abrantes, F. F. G.; Voelker, A. H. L.

2014-12-01

Planktonic foraminifera (PF) shells preserved in marine sediments are a useful tool to reconstruct productivity conditions at different geological timescales. However, the accuracy of these paleoreconstructions depends on the data set and calibration quality. Several calibration works have been defining and improving the use of proxies for productivity and nutrient cycling parameters. Our contribution is centred on a multi-proxy calibration at a regional coastal upwelling system. To minimize the existing uncertainties affecting the use of trace elements and C stable isotopes as productivity proxy in the high productivity upwelling areas, we investigate the content and distribution of Ba/Ca and δ13C in the water column, its transference into the planktonic foraminifera shells, and, how the living planktonic foraminifera Ba/Ca and δ13C signal is related to the same planktonic foraminiferal species preserved in the sediment record. This study is based on a large data set from two stations (RAIA - 75m water depth, and CALIBERIA - 350m water depth) located off the NW Iberian margin (41.5-42.5ºN; 9-10ºW), and includes: i) two year monthly water column data (temperature, salinity, nutrients, chlorophyll a, Ba/Ca, and δ13C-DIC); ii) seasonal Ba/Ca, δ13C in several living PF species at both stations; and iii) Ba/Ca and δ13C in several PF species from a large set of core-top sediment samples in the study region. Additionally, total organic carbon and total alkenones were also measured in the sediment. Our results showed the link between productivity proxies in the surface sediment foraminifera assemblage and the processes regulating the actual phytoplankton dynamics in an upwelling area. The understanding of this relationship has special relevance since it gives fundamental information related to the past oceanic biogeochemistry and/or climate and improves the prevision of future changes against possible climate variability due to anthropogenic forcing.

Millennial, centennial and decadal sea- level change in Florida, USA

Science.gov (United States)

Kemp, A.; Hawkes, A. D.; Donnelly, J. P.; Horton, B. P.

2012-12-01

Reconstructions of relative sea-level changes on millennial timescales provide data against which to test and calibrate Earth-Ice models. On the U.S. mid-Atlantic coast they constrain the geometry of the Laurentide Ice Sheet's collapsing forebulge. Sea -level data from southeastern Atlantic coast additionally constrain ice-equivalent meltwater input. Here we produce the first Holocene sea-level curve for Florida and Georgia from the St. Mary's River using agglutinated foraminifera preserved in radiocarbon-dated brackish and salt-marsh sediment. The use of foraminfera as sea-level indicators was underpinned by local and regional datasets describing the modern distribution of assemblages that are analogues for those preserved in buried sediment. This approach produced 25 index points that record 5.2 m of relative sea level rise over the last 8000 years with no evidence of a mid Holocene high stand. These reconstructions indicate that existing GIA models do not replicate proxy reconstructions and that northern Florida is subsiding in response to ongoing forebulge collapse at an estimated rate of approximately 0.3 mm/yr. Over multi decadal time scales, detailed sea level reconstructions provide an appropriate geological context for modern rates of sea-level rise. Reconstructions spanning the last 2000 years of known climate variability are important for developing models with predictive capacity that link climate and sea level changes. A reconstruction of sea-level changes since 2000 years BP was developed using a core of brackish marsh sediment from the Nassau River in Florida. Foraminifera estimated the elevation of former sea level with an uncertainty of ± 10 cm. Consistent downcore assemblages indicate that the marsh maintained its tidal elevation for 2000 years. An age depth model was developed for the core results from radiocarbon dating, 210Pb and 137Cs. The resulting relative sea level record was adjusted for the contribution made by glacio

Locating Noctiluca miliaris in the Arabian Sea: An optical proxy approach

Digital Repository Service at National Institute of Oceanography (India)

Thibodeau, P.S.; Roesler, C.S.; Drapeau, S.L.; Matondkar, S.G.P.; Goes, J.I.; Werdell, P.J.

of the bloom as identified by the ocean color Chl imagery, indicating that in situ observations may be necessary to resolve community structure, particularly for populations below the surface. The Arabian Sea is one of the most productive regions in the world... these composite images. Black circles indicate in situ sampling stations. Regions of gray and black indicate land and no satellite retrievals, respectively. We acquired these MODISA data from the NASA Ocean Biology Processing Group (OBPG) at Goddard Space Flight...

Testing the fidelity of laminations as a proxy for oxygen concentration in the Bering Sea over millennial to orbital timescales

Science.gov (United States)

Black, A. E.; Baranow, N.; Amdur, S.; Cook, M. S.

2017-12-01

Ocean circulation and biological productivity play an important role in the climate system through their contribution to global heat transport and air-sea exchange of CO­2. Oceanic oxygen concentration provides insight to ocean circulation and biological productivity. Sediment laminations provide a valuable proxy for local oceanic oxygen concentration. Many sediment cores from the Pacific Ocean are laminated from the last deglaciation, but previous studies have not provided an in-depth examination of laminations over many glacial and interglacial (G/IG) cycles. Typically, studies to date that consider bioturbation as a proxy for oxygen concentration have only considered one sediment core from a site, leaving ambiguity as to whether laminations faithfully record local oxygen levels. With sediment cores from three different holes (A, C, D) on the northern Bering Slope from IODP site U1345 (1008m), we investigate how faithfully laminations record oxygen concentration. We assign a bioturbation index from 1 to 4 for 1-cm intervals for the cores from each of the three holes and align the holes based on physical properties data. We find that the bioturbation is relatively consistent (within one bioturbation unit) between holes, suggesting that laminations may be a faithful, if not perfect, proxy for local oxygen concentration. After examining laminations from a complete hole, representing over 500,000 years, there seems to be no consistent pattern of laminations during the past five glacial cycles, suggesting there is no consistent pattern to oxygen concentration during glacial periods in the northern Bering Slope. Thus, hypotheses on ocean circulation and productivity in the northern Bering Sea from the last deglaciation may not apply to previous G/IG cycles.

Development of the Wintertime Sr/Ca-SST Record from Red Sea Corals as a Proxy for the North Atlantic Oscillation

Science.gov (United States)

Bernstein, W. N.; Hughen, K. A.

2009-12-01

-weekly temporal resolution for downcore SST reconstructions over the past 140 years, which will be used to evaluate the ability of the coral proxies to capture instrumental NAO variability. We expect that this winter Sr/Ca record will exhibit coherence with the NAO similar to that evident between Red Sea instrumental SST and the NAO index. Future work will involve construction of an NAO record back ~400 years, using the multi-core Sr/Ca-SST calibration applied to a combination of new records from modern and fossil coral material. This record will be examined to identify changes in NAO behavior as a function of frequency, and to compare frequency-dependent NAO variability between periods of relatively warm and cold hemispheric climate. This analysis will allow us to test the hypothesized link between NAO behavior and mean climate conditions, and if confirmed, improve predictions regarding the role of the NAO in impending climate change. References Hurrell, J. et al., 2003, in The North Atlantic Oscillation: Climatic Significance and Environmental Impact, 1-36 (A.G.U., Washington, D.C.). Visbeck, M. et al., 2001, Proc. Nat. Acad. Sci. 98, 12876-12877.

Controls on Arctic sea ice from first-year and multi-year survival rates

Energy Technology Data Exchange (ETDEWEB)

Hunke, Jes [Los Alamos National Laboratory

2009-01-01

The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi year ice. The transition to an Arctic that is populated by thinner first year sea ice has important implications for future trends in area and volume. Here we develop a reduced model for Arctic sea ice with which we investigate how the survivability of first year and multi year ice control the mean state, variability, and trends in ice area and volume.

Validity of proxies and correction for proxy use when evaluating social determinants of health in stroke patients.

Science.gov (United States)

Skolarus, Lesli E; Sánchez, Brisa N; Morgenstern, Lewis B; Garcia, Nelda M; Smith, Melinda A; Brown, Devin L; Lisabeth, Lynda D

2010-03-01

The purpose of this study was to evaluate stroke patient-proxy agreement with respect to social determinants of health, including depression, optimism, and spirituality, and to explore approaches to minimize proxy-introduced bias. Stroke patient-proxy pairs from the Brain Attack Surveillance in Corpus Christi Project were interviewed (n=34). Evaluation of agreement between patient-proxy pairs included calculation of intraclass correlation coefficients, linear regression models (ProxyResponse=alpha(0)+alpha(1)PatientResponse+delta, where alpha(0)=0 and alpha(1)=1 denotes no bias) and kappa statistics. Bias introduced by proxies was quantified with simulation studies. In the simulated data, we applied 4 approaches to estimate regression coefficients of stroke outcome social determinants of health associations when only proxy data were available for some patients: (1) substituting proxy responses in place of patient responses; (2) including an indicator variable for proxy use; (3) using regression calibration with external validation; and (4) internal validation. Agreement was fair for depression (intraclass correlation coefficient, 0.41) and optimism (intraclass correlation coefficient, 0.48) and moderate for spirituality (kappa, 0.48 to 0.53). Responses of proxies were a biased measure of the patients' responses for depression, with alpha(0)=4.88 (CI, 2.24 to 7.52) and alpha(1)=0.39 (CI, 0.09 to 0.69), and for optimism, with alpha(0)=3.82 (CI, -1.04 to 8.69) and alpha(1)=0.81 (CI, 0.41 to 1.22). Regression calibration with internal validation was the most accurate method to correct for proxy-induced bias. Fair/moderate patient-proxy agreement was observed for social determinants of health. Stroke researchers who plan to study social determinants of health may consider performing validation studies so corrections for proxy use can be made.

Multi-proxy evidence of long-term changes in ecosystem structure in a Danish marine estuary, linked to increased nutrient loading

DEFF Research Database (Denmark)

Ellegaard, Marianne; Clarke, A.L.; Reuss, Nina Steenberg

2006-01-01

This paper presents a study of changes in eutrophication over the past 100 years in a fertile estuary. The Danish estuary Mariager Fjord is a long, narrow sill-fjord with a permanently anoxic basin. In 1997 anoxia spread from the basin to the entire inner estuary, killing almost all eukaryotes...... and prompting debate on the causes. This paper reports a multi-proxy survey of 210Pb-dated sediment cores from the anoxic basin. Analyses of diatoms, dinoflagellates, pigments and geochemical proxies were used to determine changes in ecosystem structure over the past 100 years. The aim was to establish ‘base...... and natural isotopes (d13C, d15N) suggested increasing production and nutrient loading. The main changes in the biological proxies occurred between 1915 and the 1940s, and indicated that the estuary has been somewhat eutrophic since 1900, but that the eutrophication process increased over the past 100 years...

Sea-land segmentation for infrared remote sensing images based on superpixels and multi-scale features

Science.gov (United States)

Lei, Sen; Zou, Zhengxia; Liu, Dunge; Xia, Zhenghuan; Shi, Zhenwei

2018-06-01

Sea-land segmentation is a key step for the information processing of ocean remote sensing images. Traditional sea-land segmentation algorithms ignore the local similarity prior of sea and land, and thus fail in complex scenarios. In this paper, we propose a new sea-land segmentation method for infrared remote sensing images to tackle the problem based on superpixels and multi-scale features. Considering the connectivity and local similarity of sea or land, we interpret the sea-land segmentation task in view of superpixels rather than pixels, where similar pixels are clustered and the local similarity are explored. Moreover, the multi-scale features are elaborately designed, comprising of gray histogram and multi-scale total variation. Experimental results on infrared bands of Landsat-8 satellite images demonstrate that the proposed method can obtain more accurate and more robust sea-land segmentation results than the traditional algorithms.

Exploring the potential of clumped isotope thermometry on coccolith-rich sediments as a sea surface temperature proxy

Science.gov (United States)

Drury, Anna Joy; John, Cédric M.

2016-10-01

Understanding past changes in sea surface temperatures (SSTs) is crucial; however, existing proxies for reconstructing past SSTs are hindered by unknown ancient seawater composition (foraminiferal Mg/Ca and δ18O) or reflect subsurface temperatures (TEX86) or have a limited applicable temperature range (U37k'). We examine clumped isotope (Δ47) thermometry to fossil coccolith-rich material as an SST proxy, as clumped isotopes are independent of original seawater composition and applicable to a wide temperature range and coccolithophores are widespread and dissolution resistant. The Δ47-derived temperatures from 63 μm fraction removes most nonmixed layer components; however, the Δ47-derived temperatures display an unexpected slight decreasing trend with decreasing size fraction. This unexpected trend could partly arise because larger coccoliths (5-12 μm) are removed during the size fraction separation process. The c1 and <63 μm c2 Δ47-derived temperatures are comparable to concurrent U37k' SSTs. The <20, <10, and 2-5 μm c2 Δ47-derived temperatures are consistently cooler than expected. The Δ47-U37k' temperature offset is probably caused by abiotic/diagenetic calcite present in the c2 2-5 μm fraction (˜53% by area), which potentially precipitated at bottom water temperatures of ˜6°C. Our results indicate that clumped isotopes on coccolith-rich sediment fractions have potential as an SST proxy, particularly in tropical regions, providing that careful investigation of the appropriate size fraction for the region and time scale is undertaken.

ABC of multi-fractal spacetimes and fractional sea turtles

Energy Technology Data Exchange (ETDEWEB)

Calcagni, Gianluca [Instituto de Estructura de la Materia, CSIC, Madrid (Spain)

2016-04-15

We clarify what it means to have a spacetime fractal geometry in quantum gravity and show that its properties differ from those of usual fractals. A weak and a strong definition of multi-scale and multi-fractal spacetimes are given together with a sketch of the landscape of multi-scale theories of gravitation. Then, in the context of the fractional theory with q-derivatives, we explore the consequences of living in a multi-fractal spacetime. To illustrate the behavior of a non-relativistic body, we take the entertaining example of a sea turtle. We show that, when only the time direction is fractal, sea turtles swim at a faster speed than in an ordinary world, while they swim at a slower speed if only the spatial directions are fractal. The latter type of geometry is the one most commonly found in quantum gravity. For time-like fractals, relativistic objects can exceed the speed of light, but strongly so only if their size is smaller than the range of particle-physics interactions. We also find new results about log-oscillating measures, the measure presentation and their role in physical observations and in future extensions to nowhere-differentiable stochastic spacetimes. (orig.)

ABC of multi-fractal spacetimes and fractional sea turtles

International Nuclear Information System (INIS)

Calcagni, Gianluca

2016-01-01

We clarify what it means to have a spacetime fractal geometry in quantum gravity and show that its properties differ from those of usual fractals. A weak and a strong definition of multi-scale and multi-fractal spacetimes are given together with a sketch of the landscape of multi-scale theories of gravitation. Then, in the context of the fractional theory with q-derivatives, we explore the consequences of living in a multi-fractal spacetime. To illustrate the behavior of a non-relativistic body, we take the entertaining example of a sea turtle. We show that, when only the time direction is fractal, sea turtles swim at a faster speed than in an ordinary world, while they swim at a slower speed if only the spatial directions are fractal. The latter type of geometry is the one most commonly found in quantum gravity. For time-like fractals, relativistic objects can exceed the speed of light, but strongly so only if their size is smaller than the range of particle-physics interactions. We also find new results about log-oscillating measures, the measure presentation and their role in physical observations and in future extensions to nowhere-differentiable stochastic spacetimes. (orig.)

ABC of multi-fractal spacetimes and fractional sea turtles

Science.gov (United States)

Calcagni, Gianluca

2016-04-01

We clarify what it means to have a spacetime fractal geometry in quantum gravity and show that its properties differ from those of usual fractals. A weak and a strong definition of multi-scale and multi-fractal spacetimes are given together with a sketch of the landscape of multi-scale theories of gravitation. Then, in the context of the fractional theory with q-derivatives, we explore the consequences of living in a multi-fractal spacetime. To illustrate the behavior of a non-relativistic body, we take the entertaining example of a sea turtle. We show that, when only the time direction is fractal, sea turtles swim at a faster speed than in an ordinary world, while they swim at a slower speed if only the spatial directions are fractal. The latter type of geometry is the one most commonly found in quantum gravity. For time-like fractals, relativistic objects can exceed the speed of light, but strongly so only if their size is smaller than the range of particle-physics interactions. We also find new results about log-oscillating measures, the measure presentation and their role in physical observations and in future extensions to nowhere-differentiable stochastic spacetimes.

Rayleigh-based, multi-element coral thermometry: A biomineralization approach to developing climate proxies

Science.gov (United States)

Gaetani, G.A.; Cohen, A.L.; Wang, Z.; Crusius, John

2011-01-01

This study presents a new approach to coral thermometry that deconvolves the influence of water temperature on skeleton composition from that of “vital effects”, and has the potential to provide estimates of growth temperatures that are accurate to within a few tenths of a degree Celsius from both tropical and cold-water corals. Our results provide support for a physico-chemical model of coral biomineralization, and imply that Mg2+ substitutes directly for Ca2+ in biogenic aragonite. Recent studies have identified Rayleigh fractionation as an important influence on the elemental composition of coral skeletons. Daily, seasonal and interannual variations in the amount of aragonite precipitated by corals from each “batch” of calcifying fluid can explain why the temperature dependencies of elemental ratios in coral skeleton differ from those of abiogenic aragonites, and are highly variable among individual corals. On the basis of this new insight into the origin of “vital effects” in coral skeleton, we developed a Rayleigh-based, multi-element approach to coral thermometry. Temperature is resolved from the Rayleigh fractionation signal by combining information from multiple element ratios (e.g., Mg/Ca, Sr/Ca, Ba/Ca) to produce a mathematically over-constrained system of Rayleigh equations. Unlike conventional coral thermometers, this approach does not rely on an initial calibration of coral skeletal composition to an instrumental temperature record. Rather, considering coral skeletogenesis as a biologically mediated, physico-chemical process provides a means to extract temperature information from the skeleton composition using the Rayleigh equation and a set of experimentally determined partition coefficients. Because this approach is based on a quantitative understanding of the mechanism that produces the “vital effect” it should be possible to apply it both across scleractinian species and to corals growing in vastly different environments. Where

Reconstruction of Local Sea Levels at South West Pacific Islands—A Multiple Linear Regression Approach (1988-2014)

Science.gov (United States)

Kumar, V.; Melet, A.; Meyssignac, B.; Ganachaud, A.; Kessler, W. S.; Singh, A.; Aucan, J.

2018-02-01

Rising sea levels are a critical concern in small island nations. The problem is especially serious in the western south Pacific, where the total sea level rise over the last 60 years has been up to 3 times the global average. In this study, we aim at reconstructing sea levels at selected sites in the region (Suva, Lautoka—Fiji, and Nouméa—New Caledonia) as a multilinear regression (MLR) of atmospheric and oceanic variables. We focus on sea level variability at interannual-to-interdecadal time scales, and trend over the 1988-2014 period. Local sea levels are first expressed as a sum of steric and mass changes. Then a dynamical approach is used based on wind stress curl as a proxy for the thermosteric component, as wind stress curl anomalies can modulate the thermocline depth and resultant sea levels via Rossby wave propagation. Statistically significant predictors among wind stress curl, halosteric sea level, zonal/meridional wind stress components, and sea surface temperature are used to construct a MLR model simulating local sea levels. Although we are focusing on the local scale, the global mean sea level needs to be adjusted for. Our reconstructions provide insights on key drivers of sea level variability at the selected sites, showing that while local dynamics and the global signal modulate sea level to a given extent, most of the variance is driven by regional factors. On average, the MLR model is able to reproduce 82% of the variance in island sea level, and could be used to derive local sea level projections via downscaling of climate models.

Monitoring the Dead Sea Region by Multi-Parameter Stations

Science.gov (United States)

Mohsen, A.; Weber, M. H.; Kottmeier, C.; Asch, G.

2015-12-01

The Dead Sea Region is an exceptional ecosystem whose seismic activity has influenced all facets of the development, from ground water availability to human evolution. Israelis, Palestinians and Jordanians living in the Dead Sea region are exposed to severe earthquake hazard. Repeatedly large earthquakes (e.g. 1927, magnitude 6.0; (Ambraseys, 2009)) shook the whole Dead Sea region proving that earthquake hazard knows no borders and damaging seismic events can strike anytime. Combined with the high vulnerability of cities in the region and with the enormous concentration of historical values this natural hazard results in an extreme earthquake risk. Thus, an integration of earthquake parameters at all scales (size and time) and their combination with data of infrastructure are needed with the specific aim of providing a state-of-the-art seismic hazard assessment for the Dead Sea region as well as a first quantitative estimate of vulnerability and risk. A strong motivation for our research is the lack of reliable multi-parameter ground-based geophysical information on earthquakes in the Dead Sea region. The proposed set up of a number of observatories with on-line data access will enable to derive the present-day seismicity and deformation pattern in the Dead Sea region. The first multi-parameter stations were installed in Jordan, Israel and Palestine for long-time monitoring. All partners will jointly use these locations. All stations will have an open data policy, with the Deutsches GeoForschungsZentrum (GFZ, Potsdam, Germany) providing the hard and software for real-time data transmission via satellite to Germany, where all partners can access the data via standard data protocols.

The Last Millennium Reanalysis: Improvements to proxies and proxy modeling

Science.gov (United States)

Tardif, R.; Hakim, G. J.; Emile-Geay, J.; Noone, D.; Anderson, D. M.

2017-12-01

The Last Millennium Reanalysis (LMR) employs a paleoclimate data assimilation (PDA) approach to produce climate field reconstructions (CFRs). Here, we focus on two key factors in PDA generated CFRs: the set of assimilated proxy records and forward models (FMs) used to estimate proxies from climate model output. In the initial configuration of the LMR [Hakim et al., 2016], the proxy dataset of [PAGES2k Consortium, 2013] was used, along with univariate linear FMs calibrated against annually-averaged 20th century temperature datasets. In an updated configuration, proxy records from the recent dataset [PAGES2k Consortium, 2017] are used, while a hierarchy of statistical FMs are tested: (1) univariate calibrated on annual temperature as in the initial configuration, (2) univariate against temperature as in (1) but calibration performed using expert-derived seasonality for individual proxy records, (3) as in (2) but expert proxy seasonality replaced by seasonal averaging determined objectively as part of the calibration process, (4) linear objective seasonal FMs as in (3) but objectively selecting relationships calibrated either on temperature or precipitation, and (5) bivariate linear models calibrated on temperature and precipitation with objectively-derived seasonality. (4) and (5) specifically aim at better representing the physical drivers of tree ring width proxies. Reconstructions generated using the CCSM4 Last Millennium simulation as an uninformed prior are evaluated against various 20th century data products. Results show the benefits of using the new proxy collection, particularly on the detrended global mean temperature and spatial patterns. The positive impact of using proper seasonality and temperature/moisture sensitivities for tree ring width records is also notable. This updated configuration will be used for the first generation of LMR-generated CFRs to be publicly released. These also provide a benchmark for future efforts aimed at evaluating the

The Labrador Sea during the Last Glacial Maximum: Calcite dissolution or low biogenic carbonate fluxes?

Science.gov (United States)

Marshall, Nicole; de Vernal, Anne; Mucci, Alfonso; Filippova, Alexandra; Kienast, Markus

2017-04-01

Low concentrations of biogenic carbonate characterize the sediments deposited in the Labrador Sea during the last glaciation. This may reflect poor calcite preservation and/or low biogenic carbonate productivity and fluxes. Regional bottom water ventilation was reduced during the Last Glacial Maximum (LGM), so the calcite lysocline might have been shallower than at present in the deep Labrador Sea making dissolution of calcite shells in the deep Labrador Sea possible. To address the issue, a multi-proxy approach based on micropaleontological counts (coccoliths, foraminifers, palynomorphs) and biogeochemical analyses (alkenones) was applied in the investigation of core HU2008-029-004-PC recovered in the northwestern Labrador Sea. Calcite dissolution indices based on the relative abundance benthic foraminifera shells to their organic linings as well as on fragmentation of planktonic foraminifera shells were used to evaluate changes in calcite dissolution/ preservation since the LGM. In addition, the ratio of the concentrations of coccoliths, specifically of the alkenone-producer Emiliania huxleyi, and alkenones (Emiliania huxleyi: alkenones) was explored as a potential new proxy of calcite dissolution. A sharp increase in coccoliths, foraminifers and organic linings from nearly none to substantial concentrations at 12 ka, reflect a jump to significantly greater biogenic fluxes at the glacial-interglacial transition. Furthermore, conventional dissolution indices (shells/linings of benthic foraminifera and fragmentation of planktic foraminifers) reveal that dissolution is not likely responsible for the lower glacial abundances of coccoliths and foraminifers. Only the low Emiliania huxleyi: alkenones ratios in glacial sediments could be interpreted as evidence of increased dissolution during the LGM. Given the evidence of allochthonous alkenone input into the glacial Labrador Sea, the latter observations must be treated with caution. Overall, the records indicate that

Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

Science.gov (United States)

Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.

2016-01-01

General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicate. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found through analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, an understanding of the nature of mPWP Arctic sea ice would be highly beneficial.

Spatially explicit risk approach for multi-hazard assessment and management in marine environment: The case study of the Adriatic Sea.

Science.gov (United States)

Furlan, Elisa; Torresan, Silvia; Critto, Andrea; Marcomini, Antonio

2018-03-15

In the last few decades the health of marine ecosystems has been progressively endangered by the anthropogenic presence. Natural and human-made pressures, as well as climate change effects, are posing increasing threats on marine areas, triggering alteration of biological, chemical and physical processes. Planning of marine areas has become a challenge for decision makers involved in the design of sustainable management options. In order to address threats posed by climate drivers in combination with local to regional anthropogenic pressures affecting marine ecosystems and activities, a multi-hazard assessment methodology was developed and applied to the Adriatic Sea for the reference scenario 2000-2015. Through a four-stages process based on the consecutive analysis of hazard, exposure, vulnerability and risk the methodology allows a semi-quantitative evaluation of the relative risk from anthropogenic and natural sources to multiple endpoints, thus supporting the identification and ranking of areas and targets more likely to be at risk. Resulting output showed that the higher relative hazard scores are linked to exogenic pressures (e.g. sea surface temperature variation) while the lower ones resulted from endogenic and more localized stressors (e.g. abrasion, nutrient input). Relatively very high scores were observed for vulnerability over the whole case study for almost all the considered pressures, showing seagrasses meadows, maërl and coral beds as the most susceptible targets. The approach outlined in this study provides planners and decision makers a quick-screening tool to evaluate progress towards attaining a good environmental status and to identify marine areas where management actions and adaptation strategies would be best targeted. Moreover, by focusing on risks induced by land-based drivers, resulting output can support the design of infrastructures for reducing pressures on the sea, contributing to improve the land-sea interface management

Multi Service Proxy: Mobile Web Traffic Entitlement Point in 4G Core Network

Directory of Open Access Journals (Sweden)

Dalibor Uhlir

2015-05-01

Full Text Available Core part of state-of-the-art mobile networks is composed of several standard elements like GGSN (Gateway General Packet Radio Service Support Node, SGSN (Serving GPRS Support Node, F5 or MSP (Multi Service Proxy. Each node handles network traffic from a slightly different perspective, and with various goals. In this article we will focus only on the MSP, its key features and especially on related security issues. MSP handles all HTTP traffic in the mobile network and therefore it is a suitable point for the implementation of different optimization functions, e.g. to reduce the volume of data generated by YouTube or similar HTTP-based service. This article will introduce basic features and functions of MSP as well as ways of remote access and security mechanisms of this key element in state-of-the-art mobile networks.

Predictability of twentieth century sea-level rise from past data

International Nuclear Information System (INIS)

Bittermann, Klaus; Rahmstorf, Stefan; Perrette, Mahé; Vermeer, Martin

2013-01-01

The prediction of global sea-level rise is one of the major challenges of climate science. While process-based models are still being improved to capture the complexity of the processes involved, semi-empirical models, exploiting the observed connection between global-mean sea level and global temperature and calibrated with data, have been developed as a complementary approach. Here we investigate whether twentieth century sea-level rise could have been predicted with such models given a knowledge of twentieth century global temperature increase. We find that either proxy or early tide gauge data do not hold enough information to constrain the model parameters well. However, in combination, the use of proxy and tide gauge sea-level data up to 1900 AD allows a good prediction of twentieth century sea-level rise, despite this rise being well outside the rates experienced in previous centuries during the calibration period of the model. The 90% confidence range for the linear twentieth century rise predicted by the semi-empirical model is 13–30 cm, whereas the observed interval (using two tide gauge data sets) is 14–26 cm. (letter)

Pleistocene climate change inferred from multi-proxy analyses of a loess-paleosol sequence in China

Science.gov (United States)

Wu, Yi; Qiu, Shifan; Fu, Shuqing; Rao, Zhiguo; Zhu, Zhaoyu

2018-04-01

The aeolian loess blanketing the Chinese Loess Plateau (CLP) is sensitive to climate change in monsoonal East Asia. Here, we present a multi-proxy climatic record from a Pleistocene loess-paleosol sequence from the Lantian Basin on the southern margin of the CLP. The measurements include magnetic susceptibility and related magnetic properties, bulk median grain-size, color reflectance, and the color-inferred hematite versus goethite ratio (Hm/Gt). A long-term aridification and cooling trend during the interval from ca 2.22-0.43 Ma is indicated by two magnetic grain-size proxies, corresponding to the global climatic cooling of the late Cenozoic. In addition, at least four intervals of climatic extremes are evident in the record of Hm/Gt ratio: at 1.71-1.65 Ma, 1.26-1.24 Ma, 0.94-0.86 Ma, and 0.62-0.48 Ma. These intervals are characterized by distinct regional climates, which contrast with the global climatic conditions represented in marine sediments. For example, a relatively arid climate is documented from 1.71 to 1.65 Ma, which was rapidly succeeded by a relatively humid climate which is associated with the earliest hominin (with an age of ca 1.63 Ma) in the Lantian Basin.

Pseudo-proxy evaluation of climate field reconstruction methods of North Atlantic climate based on an annually resolved marine proxy network

Directory of Open Access Journals (Sweden)

M. Pyrina

2017-10-01

Full Text Available Two statistical methods are tested to reconstruct the interannual variations in past sea surface temperatures (SSTs of the North Atlantic (NA Ocean over the past millennium based on annually resolved and absolutely dated marine proxy records of the bivalve mollusk Arctica islandica. The methods are tested in a pseudo-proxy experiment (PPE setup using state-of-the-art climate models (CMIP5 Earth system models and reanalysis data from the COBE2 SST data set. The methods were applied in the virtual reality provided by global climate simulations and reanalysis data to reconstruct the past NA SSTs using pseudo-proxy records that mimic the statistical characteristics and network of Arctica islandica. The multivariate linear regression methods evaluated here are principal component regression and canonical correlation analysis. Differences in the skill of the climate field reconstruction (CFR are assessed according to different calibration periods and different proxy locations within the NA basin. The choice of the climate model used as a surrogate reality in the PPE has a more profound effect on the CFR skill than the calibration period and the statistical reconstruction method. The differences between the two methods are clearer for the MPI-ESM model due to its higher spatial resolution in the NA basin. The pseudo-proxy results of the CCSM4 model are closer to the pseudo-proxy results based on the reanalysis data set COBE2. Conducting PPEs using noise-contaminated pseudo-proxies instead of noise-free pseudo-proxies is important for the evaluation of the methods, as more spatial differences in the reconstruction skill are revealed. Both methods are appropriate for the reconstruction of the temporal evolution of the NA SSTs, even though they lead to a great loss of variance away from the proxy sites. Under reasonable assumptions about the characteristics of the non-climate noise in the proxy records, our results show that the marine network of Arctica

Synchronous multi-decadal climate variability of the whole Pacific areas revealed in tree rings since 1567

Science.gov (United States)

Fang, Keyan; Cook, Edward; Guo, Zhengtang; Chen, Deliang; Ou, Tinghai; Zhao, Yan

2018-02-01

Oceanic and atmospheric patterns play a crucial role in modulating climate variability from interannual to multi-decadal timescales by causing large-scale co-varying climate changes. The brevity of the existing instrumental records hinders the ability to recognize climate patterns before the industrial era, which can be alleviated using proxies. Unfortunately, proxy based reconstructions of oceanic and atmospheric modes of the past millennia often have modest agreements with each other before the instrumental period, raising questions about the robustness of the reconstructions. To ensure the stability of climate signals in proxy data through time, we first identified tree-ring datasets from distant regions containing coherent variations in Asia and North America, and then interpreted their climate information. We found that the multi-decadal covarying climate patterns of the middle and high latitudinal regions around the northern Pacific Ocean agreed quite well with the climate reconstructions of the tropical and southern Pacific areas. This indicates a synchronous variability at the multi-decadal timescale of the past 430 years for the entire Pacific Ocean. This pattern is closely linked to the dominant mode of the Pacific sea surface temperature (SST) after removing the warming trend. This Pacific multi-decadal SST variability resembles the Interdecadal Pacific Oscillation.

A multi-proxy record of MIS 11-12 deglaciation and glacial MIS 12 instability from the Sulmona basin (central Italy)

Science.gov (United States)

Regattieri, Eleonora; Giaccio, Biagio; Galli, Paolo; Nomade, Sebastien; Peronace, Edoardo; Messina, Paolo; Sposato, Andrea; Boschi, Chiara; Gemelli, Maurizio

2016-01-01

A multi-proxy record (lithology, XRF, CaCO3 content, carbonate δ18O and δ13C) was acquired from a sediment core drilled in the intermountain Sulmona basin (central Italy). Tephrostratigraphic analyses of three volcanic ash layers ascribe the investigated succession to the MIS 12-MIS 11 period, spanning the interval ca. 500-410 ka. Litho-pedo facies assemblage indicates predominant lacustrine deposition, interrupted by a minor sub-aerial and lake low stand episode. Variations in major and minor elements concentrations are related to changes in the clastic input to the lake. The oxygen isotopic composition of carbonate (δ18Oc) intervals is interpreted mainly as a proxy for the amount of precipitation in the high-altitude catchment of the karst recharge system. The record shows pronounced hydrological variability at orbital and millennial time-scales, which appears closely related to the Northern Hemisphere summer insolation pattern and replicates North Atlantic and west Mediterranean Sea Surface Temperature (SST) fluctuations. The MIS 12 glacial inception is marked by an abrupt reduction of precipitation, lowering of the lake level and enhanced catchment erosion. A well-defined and isotopically prominent interstadial with increased precipitation maybe related to insolation maxima-precession minima at ca. 465 ka. This interstadial ends abruptly at ca. 457 ka and it is followed by a phase of strong short-term instability. Drastic lake-level lowering and enhanced clastic flux characterized the MIS 12 glacial maximum. Lacustrine deposition restarted about 440 ka ago. The MIS 12-MIS 11 transition is characterized by a rapid increase in the precipitation, lake-level rise and reduction in the clastic input, interrupted by a short and abrupt return to drier conditions. Comparison with marine records from the Iberian margin and western Mediterranean suggests that major events of ice rafted debris deposition, related to southward migrations of the polar front, match the

Multi-proxy constraints on sapropel formation during the late Pliocene of central Mediterranean (southwest Sicily)

Science.gov (United States)

Plancq, Julien; Grossi, Vincent; Pittet, Bernard; Huguet, Carme; Rosell-Melé, Antoni; Mattioli, Emanuela

2015-06-01

The late Pliocene (Piacenzian) in the Mediterranean region was punctuated by short-lived episodes of widespread deposition of organic-rich sedimentary layers known as sapropels. The causes of their formation remain a long-standing debate in the science community, and require disentangling the roles of climatic/oceanographic processes that triggered higher primary productivity or enhanced organic matter preservation. The lack of data, especially of sea temperatures at sufficient temporal resolution, is one of the main challenges to solve this debate. Here, we present new organic geochemistry and micropaleontological data from the late Pliocene at Punta Grande/Punta Piccola sections (southwest Sicily) that allow untangling the mechanisms that favored the formation of two sapropel series (noted S and A) in the central Mediterranean area during this period. Sea surface (SSTs) and subsurface temperatures were estimated using three distinct organic geochemical proxies namely the alkenone unsaturation index (UK‧37), the long-chain diol index (LDI) and the tetraether index (TEX86). Reconstructed SSTs are relatively stable throughout the late Pliocene and ∼4 °C higher than modern Mediterranean SSTs, which is consistent with the climatic conditions inferred for this period from paleoclimate modeling. An increase in SST is, however, recorded by UK‧37 and LDI proxies across each sapropel horizon, supporting that the two sapropel series S and A were formed during warmer climate conditions. The comparison of SST data with variations in accumulation rates of total organic carbon and lipid-biomarkers (alkenones, long-chain alkyl diols, archaeal and bacterial tetraethers), and with changes in calcareous nannofossil assemblages, indicates that the studied sapropels might have formed under different environmental conditions. The first series of sapropels (S), deposited between 3.1 and 2.8 Ma, is likely due to a better preservation of organic matter, induced by the development

Heinrich event 4 characterized by terrestrial proxies in southwestern Europe

Directory of Open Access Journals (Sweden)

J. M. López-García

2013-05-01

Full Text Available Heinrich event 4 (H4 is well documented in the North Atlantic Ocean as a cooling event that occurred between 39 and 40 Ka. Deep-sea cores around the Iberian Peninsula coastline have been analysed to characterize the H4 event, but there are no data on the terrestrial response to this event. Here we present for the first time an analysis of terrestrial proxies for characterizing the H4 event, using the small-vertebrate assemblage (comprising small mammals, squamates and amphibians from Terrassa Riera dels Canyars, an archaeo-palaeontological deposit located on the seaboard of the northeastern Iberian Peninsula. This assemblage shows that the H4 event is characterized in northeastern Iberia by harsher and drier terrestrial conditions than today. Our results were compared with other proxies such as pollen, charcoal, phytolith, avifauna and large-mammal data available for this site, as well as with the general H4 event fluctuations and with other sites where H4 and the previous and subsequent Heinrich events (H5 and H3 have been detected in the Mediterranean and Atlantic regions of the Iberian Peninsula. We conclude that the terrestrial proxies follow the same patterns as the climatic and environmental conditions detected by the deep-sea cores at the Iberian margins.

A sea-land segmentation algorithm based on multi-feature fusion for a large-field remote sensing image

Science.gov (United States)

Li, Jing; Xie, Weixin; Pei, Jihong

2018-03-01

Sea-land segmentation is one of the key technologies of sea target detection in remote sensing images. At present, the existing algorithms have the problems of low accuracy, low universality and poor automatic performance. This paper puts forward a sea-land segmentation algorithm based on multi-feature fusion for a large-field remote sensing image removing island. Firstly, the coastline data is extracted and all of land area is labeled by using the geographic information in large-field remote sensing image. Secondly, three features (local entropy, local texture and local gradient mean) is extracted in the sea-land border area, and the three features combine a 3D feature vector. And then the MultiGaussian model is adopted to describe 3D feature vectors of sea background in the edge of the coastline. Based on this multi-gaussian sea background model, the sea pixels and land pixels near coastline are classified more precise. Finally, the coarse segmentation result and the fine segmentation result are fused to obtain the accurate sea-land segmentation. Comparing and analyzing the experimental results by subjective vision, it shows that the proposed method has high segmentation accuracy, wide applicability and strong anti-disturbance ability.

Witnessing entanglement by proxy

International Nuclear Information System (INIS)

Bäuml, Stefan; Bruß, Dagmar; Kampermann, Hermann; Huber, Marcus; Winter, Andreas

2016-01-01

Entanglement is a ubiquitous feature of low temperature systems and believed to be highly relevant for the dynamics of condensed matter properties and quantum computation even at higher temperatures. The experimental certification of this paradigmatic quantum effect in macroscopic high temperature systems is constrained by the limited access to the quantum state of the system. In this paper we show how macroscopic observables beyond the mean energy of the system can be exploited as proxy witnesses for entanglement detection. Using linear and semi-definite relaxations we show that all previous approaches to this problem can be outperformed by our proxies, i.e. entanglement can be certified at higher temperatures without access to any local observable. For an efficient computation of proxy witnesses one can resort to a generalised grand canonical ensemble, enabling entanglement certification even in complex systems with macroscopic particle numbers. (paper)

Sea Spray Aerosols

DEFF Research Database (Denmark)

Butcher, Andrew Charles

emissions produced directly from bubble bursting as the result of air entrainment from breaking waves and particles generated from secondary emissions of volatile organic compounds. In the first paper, we study the chemical properties of particles produced from several sea water proxies with the use...... of a cloud condensation nuclei ounter. Proxy solutions with high inorganic salt concentrations and some organics produce sea spray aerosol particles with little change in cloud condensation activity relative to pure salts. Comparison is made between a frit based method for bubble production and a plunging...... a relationship between plunging jet particle ux, oceanic particle ux, and energy dissipation rate in both systems. Previous sea spray aerosol studies dissipate an order of magnitude more energy for the same particle ux production as the open ocean. A scaling factor related to the energy expended in air...

TEX86 paleothermometry : proxy validation and application in marine sediments

NARCIS (Netherlands)

Huguet, C.

2007-01-01

Determination of past sea surface temperature (SST) is of primary importance for the reconstruction of natural climatic changes, modelling of climate and reconstruction of ocean circulation. Recently, a new SST proxy was introduced, the TetraEther indeX of lipids with 86 carbons (TEX86), which is

TEX₈₆ paleothermometry : proxy validation and application in marine sediments

NARCIS (Netherlands)

Huguet, Carme

2007-01-01

Determination of past sea surface temperature (SST) is of primary importance for the reconstruction of natural climatic changes, modelling of climate and reconstruction of ocean circulation. Recently, a new SST proxy was introduced, the TetraEther indeX of lipids with 86 carbons (TEX₈₆), which is

Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present.

Science.gov (United States)

Hoff, Ulrike; Rasmussen, Tine L; Stein, Ruediger; Ezat, Mohamed M; Fahl, Kirsten

2016-07-26

In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold stadials and Heinrich events, respectively. Low-salinity surface water and the sea ice edge spreads to the Greenland-Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean.

Middle to Late Pleistocene multi-proxy record of environmental response to climate change from the Vienna Basin, Central Europe (Austria)

Science.gov (United States)

Salcher, Bernhard C.; Frank-Fellner, Christa; Lomax, Johanna; Preusser, Frank; Ottner, Franz; Scholger, Robert; Wagreich, Michael

2017-10-01

Tectonic basins can represent valuable archives of the environmental history. Presented here are the stratigraphy and multi-proxy analyses of two adjacent alluvial fans in the Quaternary active parts of the Vienna Basin, situated at the interface of the Atlantic, European continental and Mediterranean climate. Deposits comprise a sequence of coarse-grained fluvial deposits intercalated by laterally extensive horizons of pedogenically altered fine sediments. To establish palaeoenvironmental reconstructions, fine-grained sequences from a drill core and outcrop data were analysed according to its malacofauna, palaeopedology, susceptibility and sedimentology. The chronological framework is provided by 38 luminescence ages and supported by geomagnetic polarity investigations. Distinct warm periods each associated with a geomagnetic excursion, are recorded in three pedocomplexes formed during the Last Interglacial and two earlier interglacial periods, indicted to correlate with Marine Isotope Stage (MIS) 9 and MIS 11, respectively. Environmental conditions during the early last glacial period (MIS 5, c. 100-70 ka) are reconstructed from mollusc-shell rich overbank fines deposited along a former channel belt, covered by massive sheetflood deposits during MIS 2. Analysed warm phases suggest strong variations in humidity, ranging from steppe to forest dominated environments. The study presents one of the few numerically dated Middle Pleistocene multi-proxy records and one of the most comprehensive malacological datasets covering the early phases of last glacial period of continental Europe.

Unearthing earthquakes and their tsunamis using multiple proxies: the 22 June 1932 event and a probable fourteenth-century predecessor on the Pacific coast of Mexico

Czech Academy of Sciences Publication Activity Database

Ramírez-Herrera, M.-T.; Corona, N.; Lagos, M.; Černý, Jan; Goguitchaichvili, A.; Goff, J.; Chaugé-Goff, C.; Machain, M. L.; Zawadzki, A.; Jacobsen, G.; Carranza-Edwards, A.; Lozano, S.; Blecher, L.

2014-01-01

Roč. 56, č. 13 (2014), s. 1584-1601 ISSN 0020-6814 Institutional support: RVO:67985831 Keywords : tsunami deposits * palaeotsunami * tropical environment * multi-proxy approach * Pacific coast * México Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.708, year: 2014

Millennial-scale variability of marine productivity and terrigenous matter supply in the western Bering Sea over the past 180 kyr

Directory of Open Access Journals (Sweden)

J.-R. Riethdorf

2013-06-01

Full Text Available We used piston cores recovered in the western Bering Sea to reconstruct millennial-scale changes in marine productivity and terrigenous matter supply over the past ~180 kyr. Based on a geochemical multi-proxy approach, our results indicate closely interacting processes controlling marine productivity and terrigenous matter supply comparable to the situation in the Okhotsk Sea. Overall, terrigenous inputs were high, whereas export production was low. Minor increases in marine productivity occurred during intervals of Marine Isotope Stage 5 and interstadials, but pronounced maxima were recorded during interglacials and Termination I. The terrigenous material is suggested to be derived from continental sources on the eastern Bering Sea shelf and to be subsequently transported via sea ice, which is likely to drive changes in surface productivity, terrigenous inputs, and upper-ocean stratification. From our results we propose glacial, deglacial, and interglacial scenarios for environmental change in the Bering Sea. These changes seem to be primarily controlled by insolation and sea-level forcing which affect the strength of atmospheric pressure systems and sea-ice growth. The opening history of the Bering Strait is considered to have had an additional impact. High-resolution core logging data (color b*, XRF scans strongly correspond to the Dansgaard–Oeschger climate variability registered in the NGRIP ice core and support an atmospheric coupling mechanism of Northern Hemisphere climates.

A scattering approach to sea wave diffraction

Energy Technology Data Exchange (ETDEWEB)

Corradini, M. L., E-mail: letizia.corradini@unicam.it; Garbuglia, M., E-mail: milena.garbuglia@unicam.it; Maponi, P., E-mail: pierluigi.maponi@unicam.it [University of Camerino, via Madonna delle Carceri, 9, 62032, Camerino (Italy); Ruggeri, M., E-mail: ru.marco@faggiolatipumps.it [Faggiolati Pumps S.p.A., Z.Ind Sforzacosta, 62100, Macerata (Italy)

2016-06-08

This paper intends to show a model for the diffraction of sea waves approaching an OWC device, which converts the sea waves motion into mechanical energy and then electrical energy. This is a preliminary study to the optimisation of the device, in fact the computation of sea waves diffraction around the device allows the estimation of the sea waves energy which enters into the device. The computation of the diffraction phenomenon is the result of a sea waves scattering problem, solved with an integral equation method.

Multi-model attribution of upper-ocean temperature changes using an isothermal approach

Science.gov (United States)

Weller, Evan; Min, Seung-Ki; Palmer, Matthew D.; Lee, Donghyun; Yim, Bo Young; Yeh, Sang-Wook

2016-06-01

Both air-sea heat exchanges and changes in ocean advection have contributed to observed upper-ocean warming most evident in the late-twentieth century. However, it is predominantly via changes in air-sea heat fluxes that human-induced climate forcings, such as increasing greenhouse gases, and other natural factors such as volcanic aerosols, have influenced global ocean heat content. The present study builds on previous work using two different indicators of upper-ocean temperature changes for the detection of both anthropogenic and natural external climate forcings. Using simulations from phase 5 of the Coupled Model Intercomparison Project, we compare mean temperatures above a fixed isotherm with the more widely adopted approach of using a fixed depth. We present the first multi-model ensemble detection and attribution analysis using the fixed isotherm approach to robustly detect both anthropogenic and natural external influences on upper-ocean temperatures. Although contributions from multidecadal natural variability cannot be fully removed, both the large multi-model ensemble size and properties of the isotherm analysis reduce internal variability of the ocean, resulting in better observation-model comparison of temperature changes since the 1950s. We further show that the high temporal resolution afforded by the isotherm analysis is required to detect natural external influences such as volcanic cooling events in the upper-ocean because the radiative effect of volcanic forcings is short-lived.

Unravelling source regions of ice rafted debris within three NE Atlantic marine sediment cores during the deglacial interval: a multi-proxy approach

Science.gov (United States)

Small, David; Hibbert, Fiona; Austin, Bill

2010-05-01

Ice-rafted debris (IRD) within marine sediments of the North Atlantic provide an important archive of glacial activity on adjacent landmasses and attest to the activity of multiple calving ice margins during the last glacial cycle. IRD records therefore provide a means to reconstruct ice sheet dynamics and their interaction with the climate system, providing evidence of both the source of the ice and the location of melting (e.g. Ruddiman, 1977; Bond and Lotti, 1995). The complex interaction of the circum-Atlantic ice sheets and limitations of individual techniques often hinders firm source designations (i.e. IRD may be derived from multiple sources which cannot be differentiated by, for example, visual characterisation). Initial work identified diagnostic grain types that could be attributed to source areas of palaeo ice-sheets (eg: Bond & Lotti 1995) however, for the BIS, "diagnostic" basalt may be derived from sources to the east and west of the cores (Hibbert et al 2009, Scourse et al 2009). We therefore, utilise a multi-proxy approach to investigate the deglacial dynamics of the last British Ice Sheet (BIS) using inter alia lithic characterisation, fluxes of IRD to the core sites, magnetic susceptibility and a magnetic un-mixing model. A novel application of major element geochemistry of garnets contained within ice-rafted debris of the three high resolution marine sediment cores is presented. Garnets can be used to infer provenance (e.g. Oliver 2001) as major element composition may be assigned to specific metamorphic terranes. The IRD present within these cores is believed to be predominantly sourced from the BIS (cf: Knutz et al 2001, Hibbert et al 2009). This assertion is tested through multiple analytical techniques used and replication of records across the Hebridean shelf into the deep ocean. References • Bond, G.C. & Lotti, R., 1995. Iceberg discharges into the North Atlantic on millennial timescales during the last glaciation. Science 267. pp. 1005

Indian monsoon variability at different time scales: Marine and terrestrial proxy records

Digital Repository Service at National Institute of Oceanography (India)

Patnaik, R.; Gupta, A; Naidu, P.D.; Yadav, R.R.; Bhattacharyya, A; Kumar, M.

Here, we present a review of the work done in India during 2007-2011 on various proxy records of monsoon variability preserved in the marine (Central Indian Basin, western, northern and eastern Arabian Sea and the Bay of Bengal) and terrestrial...

Calibrating multiple isotopic proxies in a modern aragonite speleothem from northeast India

Science.gov (United States)

Ronay, E.; Oster, J. L.; Sharp, W. D.; Marks, N.; Erhardt, A.; Breitenbach, S. F. M.

2017-12-01

Uranium, strontium, and calcium isotope ratios in calcite speleothems are used as proxies for water-soil-rock interactions and prior calcite precipitation, and thus provide information about effective rainfall amount variations, primarily in semi-arid or highly seasonal regions. However, less is known about how these proxies function in humid regions and in aragonite speleothems. In this study, we use meteorological data to calibrate (234U/238U)i and 87Sr/86Sr in a modern aragonite speleothem from northeast India, the rainiest place on Earth, to determine how these proxies reflect effective monsoon rainfall amount. MAW-0201 is an annually laminated aragonite stalagmite that grew from 1960-2013 in Mawmluh Cave, Meghalaya, India. Rainfall here is extremely seasonal due to the Indian Summer Monsoon (ISM), which brings several meters of rain to the region each summer, but with inter-annual variability in total rainfall. The δ18O in Mawmluh dripwater and speleothems reflects moisture source and transport, rather than rainfall amount. Variations in Mg, U, and Ba concentrations in MAW-0201 show seasonal and multi-annual variability. U and Mg are closely correlated, but multi-year periods show significant anti-correlation. The Mg and U distribution coefficients in calcite and aragonite indicate correlated periods are times of prior calcite precipitation (PCP) and anti-correlated periods are times of prior aragonite precipitation (PAP) in the epikarst. We use δ44/40Ca to test this hypothesis, as Ca isotopes fractionate differently during calcite and aragonite precipitation and speleothem δ44/40Ca will record unique PAP and PCP fingerprints. We propose such shifts from PCP to PAP reflect hydrologic variability and/or flow path changes, which provide a useful tool for understanding epikarst hydrology but may also be a complicating factor in speleothem-based paleoclimate interpretations. Preliminary (234U/238U)i (always <1) and 87Sr/86Sr spanning 1991-2009 each show

Foraminifera Models to Interrogate Ostensible Proxy-Model Discrepancies During Late Pliocene

Science.gov (United States)

Jacobs, P.; Dowsett, H. J.; de Mutsert, K.

2017-12-01

Planktic foraminifera faunal assemblages have been used in the reconstruction of past oceanic states (e.g. the Last Glacial Maximum, the mid-Piacenzian Warm Period). However these reconstruction efforts have typically relied on inverse modeling using transfer functions or the modern analog technique, which by design seek to translate foraminifera into one or two target oceanic variables, primarily sea surface temperature (SST). These reconstructed SST data have then been used to test the performance of climate models, and discrepancies have been attributed to shortcomings in climate model processes and/or boundary conditions. More recently forward proxy models or proxy system models have been used to leverage the multivariate nature of proxy relationships to their environment, and to "bring models into proxy space". Here we construct ecological models of key planktic foraminifera taxa, calibrated and validated with World Ocean Atlas (WO13) oceanographic data. Multiple modeling methods (e.g. multilayer perceptron neural networks, Mahalanobis distance, logistic regression, and maximum entropy) are investigated to ensure robust results. The resulting models are then driven by a Late Pliocene climate model simulation with biogeochemical as well as temperature variables. Similarities and differences with previous model-proxy comparisons (e.g. PlioMIP) are discussed.

Sea level rise and the geoid: factor analysis approach

Directory of Open Access Journals (Sweden)

Alexey Sadovski

2013-08-01

Full Text Available Sea levels are rising around the world, and this is a particular concern along most of the coasts of the United States. A 1989 EPA report shows that sea levels rose 5-6 inches more than the global average along the Mid-Atlantic and Gulf Coasts in the last century. The main reason for this is coastal land subsidence. This sea level rise is considered more as relative sea level rise than global sea level rise. Thus, instead of studying sea level rise globally, this paper describes a statistical approach by using factor analysis of regional sea level rates of change. Unlike physical models and semi-empirical models that attempt to approach how much and how fast sea levels are changing, this methodology allows for a discussion of the factor(s that statistically affects sea level rates of change, and seeks patterns to explain spatial correlations.

Evidence of Himalayan uplift as seen in Neogene records of Indian monsoon variability from ODP Hole 722B, NW Arabian Sea

Science.gov (United States)

Muthusamy, Prakasam; Gupta, Anil K.; Saini, Naresh K.

2013-04-01

The Indian monsoon is one of the most interesting climatic features on Earth impacting most populous countries of South and East Asia. It is marked by seasonal reversals of wind direction with southwesterly winds in summer (June-September) and northeasterly winds in winter (December-February). The monsoon not only impacts socioeconomic conditions of Asia but also brings important changes in fauna and flora, ocean upwelling and primary productivity in the Arabian Sea. The Himalaya has undergone several phases of rapid uplift and exhumation since the early Miocene which led to major intensification of the Indian monsoon. The monsoon is driven by the thermal contrast between land and sea, and is intimately linked with the latitudinal movement of the Inter-Tropical Convergence Zone (ITCZ). The effect of Indian monsoon variability and the Himalayan uplift can be seen in numerous proxy records across the region. In this study we discussed about the Indian monsoon intensification and the Himalayan uplift since the early Miocene based on multi proxy records such as planktic foraminiferal relative abundances (Globigerina bulloides, Globigerinita glutinata and mixed layer species), total organic carbon (TOC), CaCO3 and elemental data from ODP Hole 722B (2028 mbsf), northwestern Arabian Sea. The TOC, CaCO3 and elemental variations of the ODP Hole 722B suggest multi phase of monsoonal intensification and Himalayan uplifts. Our results suggest that in the early Miocene (23.03 Ma) to ~15Ma, the wind strength and productivity were low. A major change is observed at ~15 Ma, during which time numerous proxies show abrupt changes. TOC, CaCO3 and Elemental analyses results reveal that a major change in the productivity, wind strength and chemical weathering starts around 15 Ma and extends up to 10 Ma. This suggests that a major Himalayan uplift occurred during ~15-10 Ma that drove Indian monsoon intensification. A similar change is also observed during 5 to 1 Ma. These long

Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy

Science.gov (United States)

Cronin, T. M.; Gemery, L.; Briggs, W.M.; Jakobsson, M.; Polyak, L.; Brouwers, E.M.

2010-01-01

Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. ?? 2010.

Proxy Graph: Visual Quality Metrics of Big Graph Sampling.

Science.gov (United States)

Nguyen, Quan Hoang; Hong, Seok-Hee; Eades, Peter; Meidiana, Amyra

2017-06-01

Data sampling has been extensively studied for large scale graph mining. Many analyses and tasks become more efficient when performed on graph samples of much smaller size. The use of proxy objects is common in software engineering for analysis and interaction with heavy objects or systems. In this paper, we coin the term 'proxy graph' and empirically investigate how well a proxy graph visualization can represent a big graph. Our investigation focuses on proxy graphs obtained by sampling; this is one of the most common proxy approaches. Despite the plethora of data sampling studies, this is the first evaluation of sampling in the context of graph visualization. For an objective evaluation, we propose a new family of quality metrics for visual quality of proxy graphs. Our experiments cover popular sampling techniques. Our experimental results lead to guidelines for using sampling-based proxy graphs in visualization.

Estimation of sedimentary proxy records together with associated uncertainty

OpenAIRE

Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; Anoop, A.; Prasad, S.; Kurths, J.

2014-01-01

Sedimentary proxy records constitute a significant portion of the recorded evidence that allows us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record intercomparisons. While there are various age-modeling approaches to improve the estimation of the age–depth relations of archives, relatively little focus has been placed on the propagation...

Precession and atmospheric CO2 modulated variability of sea ice in the central Okhotsk Sea since 130,000 years ago

Science.gov (United States)

Lo, Li; Belt, Simon T.; Lattaud, Julie; Friedrich, Tobias; Zeeden, Christian; Schouten, Stefan; Smik, Lukas; Timmermann, Axel; Cabedo-Sanz, Patricia; Huang, Jyh-Jaan; Zhou, Liping; Ou, Tsong-Hua; Chang, Yuan-Pin; Wang, Liang-Chi; Chou, Yu-Min; Shen, Chuan-Chou; Chen, Min-Te; Wei, Kuo-Yen; Song, Sheng-Rong; Fang, Tien-Hsi; Gorbarenko, Sergey A.; Wang, Wei-Lung; Lee, Teh-Quei; Elderfield, Henry; Hodell, David A.

2018-04-01

Recent reduction in high-latitude sea ice extent demonstrates that sea ice is highly sensitive to external and internal radiative forcings. In order to better understand sea ice system responses to external orbital forcing and internal oscillations on orbital timescales, here we reconstruct changes in sea ice extent and summer sea surface temperature (SSST) over the past 130,000 yrs in the central Okhotsk Sea. We applied novel organic geochemical proxies of sea ice (IP25), SSST (TEX86L) and open water marine productivity (a tri-unsaturated highly branched isoprenoid and biogenic opal) to marine sediment core MD01-2414 (53°11.77‧N, 149°34.80‧E, water depth 1123 m). To complement the proxy data, we also carried out transient Earth system model simulations and sensitivity tests to identify contributions of different climatic forcing factors. Our results show that the central Okhotsk Sea was ice-free during Marine Isotope Stage (MIS) 5e and the early-mid Holocene, but experienced variable sea ice cover during MIS 2-4, consistent with intervals of relatively high and low SSST, respectively. Our data also show that the sea ice extent was governed by precession-dominated insolation changes during intervals of atmospheric CO2 concentrations ranging from 190 to 260 ppm. However, the proxy record and the model simulation data show that the central Okhotsk Sea was near ice-free regardless of insolation forcing throughout the penultimate interglacial, and during the Holocene, when atmospheric CO2 was above ∼260 ppm. Past sea ice conditions in the central Okhotsk Sea were therefore strongly modulated by both orbital-driven insolation and CO2-induced radiative forcing during the past glacial/interglacial cycle.

On the role of density and attenuation in 3D multi-parameter visco-acoustic VTI frequency-domain FWI: an OBC case study from the North Sea

Science.gov (United States)

Operto, S.; Miniussi, A.

2018-03-01

Three-dimensional frequency-domain full waveform inversion (FWI) is applied on North Sea wide-azimuth ocean-bottom cable data at low frequencies (≤ 10 Hz) to jointly update vertical wavespeed, density and quality factor Q in the visco-acoustic VTI approximation. We assess whether density and Q should be viewed as proxy to absorb artefacts resulting from approximate wave physics or are valuable for interpretation in presence of saturated sediments and gas. FWI is performed in the frequency domain to account for attenuation easily. Multi-parameter frequency-domain FWI is efficiently performed with a few discrete frequencies following a multi-scale frequency continuation. However, grouping a few frequencies during each multi-scale step is necessary to mitigate acquisition footprint and match dispersive shallow guided waves. Q and density absorb a significant part of the acquisition footprint hence cleaning the velocity model from this pollution. Low Q perturbations correlate with low velocity zones associated with soft sediments and gas cloud. However, the amplitudes of the Q perturbations show significant variations when the inversion tuning is modified. This dispersion in the Q reconstructions is however not passed on the velocity parameter suggesting that cross-talks between first-order kinematic and second-order dynamic parameters are limited. The density model shows a good match with a well log at shallow depths. Moreover, the impedance built a posteriori from the FWI velocity and density models shows a well-focused image with however local differences with the velocity model near the sea bed where density might have absorbed elastic effects. The FWI models are finally assessed against time-domain synthetic seismogram modelling performed with the same frequency-domain modelling engine used for FWI.

Multi-proxy monitoring approaches at Kangaroo Island, South Australia

Science.gov (United States)

Dixon, Bronwyn; Drysdale, Russell; Tyler, Jonathan; Goodwin, Ian

2017-04-01

Interpretations of geochemical signals preserved in young speleothems are greatly enhanced by comprehensive cave-site monitoring. In the light of this, a cave monitoring project is being conducted concurrently with the development of a new palaeoclimate record from Kelly Hill Cave (Kangaroo Island, South Australia). The site is strategically located because it is situated between longer-lived monitoring sites in southeastern and southwestern Australia, as well as being climatically 'upstream' from major population and agricultural centres. This study aims to understand possible controls on speleothem δ18O in Kelly Hill Cave through i. identification of local and regional δ18O drivers in precipitation; and ii. preservation and modification of climatic signals within the epikarst as indicated by dripwater δ18O. These aims are achieved through analysis of a five-year daily rainfall (amount and δ18O) dataset in conjunction with in-cave drip monitoring. Drivers of precipitation δ18O were identified through linear regression between δ18O values and local meteorological variables, air-parcel back trajectories, and synoptic-typing. Synoptically driven moisture sources were identified through the use of NCEP/NCAR climate reanalysis sea-level pressure, precipitable moisture, and outgoing longwave radiation data in order to trace moisture sources and travel mechanisms from surrounding ocean basins. Local controls on δ18O at Kelly Hill Cave are consistent with published interpretations of southern Australia sites, with oxygen isotopes primarily controlled by rainfall amount on both daily and monthly time scales. Back-trajectory analysis also supports previous observations that the Southern Ocean is the major source for moisture-bearing cold-front systems. However, synoptic typing of daily rainfall δ18O and amount extremes reveals a previously unreported tropical connection and moisture source. This tropical connection appears to be strongest in summer and autumn, but

Deciphering Late-Pleistocence landscape evolution: linking proxies by combining pedo-stratigraphy and luminescence dating

Science.gov (United States)

Kreutzer, Sebastian; Meszner, Sascha; Faust, Dominik; Fuchs, Markus

2014-05-01

Interpreting former landscape evolution asks for understanding the processes that sculpt such landforms by means of deciphering complex systems. For reconstructing terrestrial Quaternary environments based on loess archives this might be considered, at least, as a three step process: (1) Identifying valuable records in appropriate morphological positions in a previously defined research area, (2) analysing the profiles by field work and laboratory methods and finally (3) linking the previously considered pseudo-isolated systems to set up a comprehensive picture. Especially the first and the last step might bring some pitfalls, as it is tempting to specify single records as pseudo-isolated, closed systems. They might be, with regard to their preservation in their specific morphological position, but in fact they are part of a complex, open system. Between 2008 and 2013, Late-Pleistocene loess archives in Saxony have been intensively investigated by field and laboratory methods. Linking pedo- and luminescence dating based chronostratigraphies, a composite profile for the entire Saxonian Loess Region has been established. With this, at least, two-fold approach we tried to avoid misinterpretations that might appear when focussing on one standard profile in an open morphological system. Our contribution focuses on this multi-proxy approach to decipher the Late-Pleistocene landscape evolution in the Saxonian Loess Region. Highlighting the challenges and advantages of combining different methods, we believe that (1) this multi-proxy approach is without alternative, (2) the combination of different profiles may simplify the more complex reality, but it may be a useful generalisation to understand and reveal the stratigraphical significance of the landscape evolution in this region.

Distinguishing Terrestrial Organic Carbon in Marginal Sediments of East China Sea and Northern South China Sea

Science.gov (United States)

Kandasamy, Selvaraj; Lin, Baozhi; Wang, Huawei; Liu, Qianqian; Liu, Zhifei; Lou, Jiann-Yuh; Chen, Chen-Tung Arthur; Mayer, Lawrence M.

2016-04-01

Knowledge about the sources, transport pathways and behavior of terrestrial organic carbon in continental margins adjoining to large rivers has improved in recent decades, but uncertainties and complications still exist with human-influenced coastal regions in densely populated wet tropics and subtropics. In these regions, the monsoon and other episodic weather events exert strong climatic control on mineral and particulate organic matter delivery to the marginal seas. Here we investigate elemental (TOC, TN and bromine-Br) and stable carbon isotopic (δ13C) compositions of organic matter (OM) in surface sediments and short cores collected from active (SW Taiwan) and passive margin (East China Sea) settings to understand the sources of OM that buried in these settings. We used sedimentary bromine to total organic carbon (Br/TOC) ratios to apportion terrigenous from marine organic matter, and find that Br/TOC may serve as an additional, reliable proxy for sedimentary provenance in both settings. Variations in Br/TOC are consistent with other provenance indicators in responding to short-lived terrigenous inputs. Because diagenetic alteration of Br is insignificant on shorter time scales, applying Br/TOC ratios as a proxy to identify organic matter source along with carbon isotope mixing models may provide additional constraints on the quantity and transformation of terrigenous organics in continental margins. We apply this combination of approaches to land-derived organic matter in different depositional environments of East Asian marginal seas.

Pattern-mixture models for analyzing normal outcome data with proxy respondents.

Science.gov (United States)

Shardell, Michelle; Hicks, Gregory E; Miller, Ram R; Langenberg, Patricia; Magaziner, Jay

2010-06-30

Studies of older adults often involve interview questions regarding subjective constructs such as perceived disability. In some studies, when subjects are unable (e.g. due to cognitive impairment) or unwilling to respond to these questions, proxies (e.g. relatives or other care givers) are recruited to provide responses in place of the subject. Proxies are usually not approached to respond on behalf of subjects who respond for themselves; thus, for each subject, data from only one of the subject or proxy are available. Typically, proxy responses are simply substituted for missing subject responses, and standard complete-data analyses are performed. However, this approach may introduce measurement error and produce biased parameter estimates. In this paper, we propose using pattern-mixture models that relate non-identifiable parameters to identifiable parameters to analyze data with proxy respondents. We posit three interpretable pattern-mixture restrictions to be used with proxy data, and we propose estimation procedures using maximum likelihood and multiple imputation. The methods are applied to a cohort of elderly hip-fracture patients. (c) 2010 John Wiley & Sons, Ltd.

Sources of multi-decadal variability in Arctic sea ice extent

International Nuclear Information System (INIS)

Day, J J; Hargreaves, J C; Annan, J D; Abe-Ouchi, A

2012-01-01

The observed dramatic decrease in September sea ice extent (SIE) has been widely discussed in the scientific literature. Though there is qualitative agreement between observations and ensemble members of the Third Coupled Model Intercomparison Project (CMIP3), it is concerning that the observed trend (1979–2010) is not captured by any ensemble member. The potential sources of this discrepancy include: observational uncertainty, physical model limitations and vigorous natural climate variability. The latter has received less attention and is difficult to assess using the relatively short observational sea ice records. In this study multi-centennial pre-industrial control simulations with five CMIP3 climate models are used to investigate the role that the Arctic oscillation (AO), the Atlantic multi-decadal oscillation (AMO) and the Atlantic meridional overturning circulation (AMOC) play in decadal sea ice variability. Further, we use the models to determine the impact that these sources of variability have had on SIE over both the era of satellite observation (1979–2010) and an extended observational record (1953–2010). There is little evidence of a relationship between the AO and SIE in the models. However, we find that both the AMO and AMOC indices are significantly correlated with SIE in all the models considered. Using sensitivity statistics derived from the models, assuming a linear relationship, we attribute 0.5–3.1%/decade of the 10.1%/decade decline in September SIE (1979–2010) to AMO driven variability. (letter)

Interactive Approach for Multi-Level Multi-Objective Fractional Programming Problems with Fuzzy Parameters

Directory of Open Access Journals (Sweden)

M.S. Osman

2018-03-01

Full Text Available In this paper, an interactive approach for solving multi-level multi-objective fractional programming (ML-MOFP problems with fuzzy parameters is presented. The proposed interactive approach makes an extended work of Shi and Xia (1997. In the first phase, the numerical crisp model of the ML-MOFP problem has been developed at a confidence level without changing the fuzzy gist of the problem. Then, the linear model for the ML-MOFP problem is formulated. In the second phase, the interactive approach simplifies the linear multi-level multi-objective model by converting it into separate multi-objective programming problems. Also, each separate multi-objective programming problem of the linear model is solved by the ∊-constraint method and the concept of satisfactoriness. Finally, illustrative examples and comparisons with the previous approaches are utilized to evince the feasibility of the proposed approach.

Mainstreaming Multi-Risk Approaches into Policy

Directory of Open Access Journals (Sweden)

Anna Scolobig

2017-12-01

Full Text Available Multi-risk environments are characterized by domino effects that often amplify the overall risk. Those include chains of hazardous events and increasing vulnerability, among other types of correlations within the risk process. The recently developed methods for multi-hazard and risk assessment integrate interactions between different risks by using harmonized procedures based on common metrics. While the products of these assessments, such as multi-hazard and -risk indexes, maps, cascade scenarios, or warning systems provide innovative and effective information, they also pose specific challenges to policy makers and practitioners due to their novel cross-disciplinary aspects. In this paper we discuss the institutional barriers to the adoption of multi-risk approaches, summarizing the results of the fieldwork conducted in Italy and Guadeloupe and of workshops with disaster risk reduction practitioners from eleven European countries. Results show the need for a clear identification of responsibilities for the implementation of multi-risk approaches, as institutional frameworks for risk reduction remain to this day primarily single-risk centered. Authorities are rarely officially responsible for the management of domino effects between e.g., tsunamis and industrial accidents, earthquake and landslides, floods and electricity network failures. Other barriers for the implementation of multi-risk approaches include the limited measures to reduce exposure at the household level, inadequate financial capacities at the local level and limited public-private partnerships, especially in case of interactions between natural and industrial risks. Adapting the scale of institutions to that of multi-risk environments remains a major challenge to better mainstream multi-risk approaches into policy. To address it, we propose a multi-risk governance framework, which includes the phases of observation, social and institutional context analysis, generation of

Towards a new paleotemperature proxy from reef coral occurrences.

Science.gov (United States)

Lauchstedt, Andreas; Pandolfi, John M; Kiessling, Wolfgang

2017-09-05

Global mean temperature is thought to have exceeded that of today during the last interglacial episode (LIG, ~ 125,000 yrs b.p.) but robust paleoclimate data are still rare in low latitudes. Occurrence data of tropical reef corals may provide new proxies of low latitude sea-surface temperatures. Using modern reef coral distributions we developed a geographically explicit model of sea surface temperatures. Applying this model to coral occurrence data of the LIG provides a latitudinal U-shaped pattern of temperature anomalies with cooler than modern temperatures around the equator and warmer subtropical climes. Our results agree with previously published estimates of LIG temperatures and suggest a poleward broadening of the habitable zone for reef corals during the LIG.

The Governance of Multi-Use Platforms at Sea for Energy Production and Aquaculture: Challenges for Policy Makers in European Seas

Directory of Open Access Journals (Sweden)

Marian Stuiver

2016-04-01

Full Text Available European seas are encountering an upsurge in competing marine activities and infrastructures. Traditional exploitation such as fisheries, tourism, transportation, and oil production are accompanied by new sustainable economic activities such as offshore windfarms, aquaculture, and tidal and wave energy. One proposed solution to overcome possible competing claims at sea lies in combining these economic activities as part of Multi-Use Platforms at Sea (MUPS. MUPS can be understood as areas at sea, designated for a combination of activities, either completely integrated in a platform or in shared marine space. MUPS can potentially benefit from each other in terms of infrastructure, maintenance, etc. Developing MUPS in the marine environment demands adequate governance. In this article, we investigate four European sites to find out how governance arrangements may facilitate or complicate MUPs. In particular, we apply a framework specifying policy, economic, social, technical, environmental, and legal (PESTEL factors to explore governance arrangements in four case study sites in different sea basins around Europe (the Mediterranean Sea, the Atlantic Ocean, the North Sea, and the Baltic Sea. The article concludes with policy recommendations on a governance regime for facilitating the development of MUPS in the future.

Impact of the initialisation on the predictability of the Southern Ocean sea ice at interannual to multi-decadal timescales

Science.gov (United States)

Zunz, Violette; Goosse, Hugues; Dubinkina, Svetlana

2015-04-01

In this study, we assess systematically the impact of different initialisation procedures on the predictability of the sea ice in the Southern Ocean. These initialisation strategies are based on three data assimilation methods: the nudging, the particle filter with sequential importance resampling and the nudging proposal particle filter. An Earth system model of intermediate complexity is used to perform hindcast simulations in a perfect model approach. The predictability of the Antarctic sea ice at interannual to multi-decadal timescales is estimated through two aspects: the spread of the hindcast ensemble, indicating the uncertainty of the ensemble, and the correlation between the ensemble mean and the pseudo-observations, used to assess the accuracy of the prediction. Our results show that at decadal timescales more sophisticated data assimilation methods as well as denser pseudo-observations used to initialise the hindcasts decrease the spread of the ensemble. However, our experiments did not clearly demonstrate that one of the initialisation methods systematically provides with a more accurate prediction of the sea ice in the Southern Ocean than the others. Overall, the predictability at interannual timescales is limited to 3 years ahead at most. At multi-decadal timescales, the trends in sea ice extent computed over the time period just after the initialisation are clearly better correlated between the hindcasts and the pseudo-observations if the initialisation takes into account the pseudo-observations. The correlation reaches values larger than 0.5 in winter. This high correlation has likely its origin in the slow evolution of the ocean ensured by its strong thermal inertia, showing the importance of the quality of the initialisation below the sea ice.

A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multi-frequency EM

Science.gov (United States)

Hendricks, S.; Hoppmann, M.; Hunkeler, P. A.; Kalscheuer, T.; Gerdes, R.

2015-12-01

In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise and accumulate beneath nearby sea ice to form a several meter thick sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator for ice - ocean interactions. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and sub-ice platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions from platelet-layer conductivities using Archie's Law. The thickness results agreed well with drill-hole validation datasets within the uncertainty range, and the ice-volume fraction also yielded plausible results. Our findings imply that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties. However, we emphasize that the successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model.

Are Sea Surface Temperature satellite measurements reliable proxies of lagoon temperature in the South Pacific?

Science.gov (United States)

Van Wynsberge, Simon; Menkes, Christophe; Le Gendre, Romain; Passfield, Teuru; Andréfouët, Serge

2017-12-01

In remote coral reef environments, lagoon and reef in situ measurements of temperature are scarce. Sea Surface Temperature (SST) measured by satellite has been frequently used as a proxy of the lagoon temperature experienced by coral reef organisms (TL) especially during coral bleaching events. However, the link between SST and TL is poorly characterized. First, we compared the correlation between various SST series and TL from 2012 to 2016 in three atolls and one island in the Central South Pacific Ocean. Simple linear correlation between SST and TL ranged between 0.44 and 0.97 depending on lagoons, localities of sensors, and type of SST data. High-resolution-satellite-measurements of SST inside the lagoons did not outperform oceanic SST series, suggesting that SST products are not adapted for small lagoons. Second, we modelled the difference between oceanic SST and TL as a function of the drivers of lagoon water renewal and mixing, namely waves, tide, wind, and season. The multivariate models reduced significantly the bias between oceanic SST and TL. In atoll lagoons, and probably in other hydrodynamically semi-open systems, a correction taking into account these factors is necessary when SST are used to characterize organisms' thermal stress thresholds.

Salinity controls on Na incorporation in Red Sea planktonic foraminifera

Science.gov (United States)

Mezger, E. M.; de Nooijer, L. J.; Boer, W.; Brummer, G. J. A.; Reichart, G. J.

2016-12-01

Whereas several well-established proxies are available for reconstructing past temperatures, salinity remains challenging to assess. Reconstructions based on the combination of (in)organic temperature proxies and foraminiferal stable oxygen isotopes result in relatively large uncertainties, which may be reduced by application of a direct salinity proxy. Cultured benthic and planktonic foraminifera showed that Na incorporation in foraminiferal shell calcite provides a potential independent proxy for salinity. Here we present the first field calibration of such a potential proxy. Living planktonic foraminiferal specimens from the Red Sea surface waters were collected and analyzed for their Na/Ca content using laser ablation quadrupole inductively coupled plasma mass spectrometry. Using the Red Sea as a natural laboratory, the calibration covers a broad range of salinities over a steep gradient within the same water mass. For both Globigerinoides ruber and Globigerinoides sacculifer calcite Na/Ca increases with salinity, albeit with a relatively large intraspecimen and interspecimen variability. The field-based calibration is similar for both species from a salinity of 36.8 up to 39.6, while values for G. sacculifer deviate from this trend in the northernmost transect. It is hypothesized that the foraminifera in the northernmost part of the Red Sea are (partly) expatriated and hence should be excluded from the Na/Ca-salinity calibration. Incorporation of Na in foraminiferal calcite therefore provides a potential proxy for salinity, although species-specific calibrations are still required and more research on the effect of temperature is needed.

MULTI-TEMPORAL REMOTE SENSING IMAGE CLASSIFICATION - A MULTI-VIEW APPROACH

Data.gov (United States)

National Aeronautics and Space Administration — MULTI-TEMPORAL REMOTE SENSING IMAGE CLASSIFICATION - A MULTI-VIEW APPROACH VARUN CHANDOLA AND RANGA RAJU VATSAVAI Abstract. Multispectral remote sensing images have...

Towards breaking the spatial resolution barriers: An optical flow and super-resolution approach for sea ice motion estimation

Science.gov (United States)

Petrou, Zisis I.; Xian, Yang; Tian, YingLi

2018-04-01

Estimation of sea ice motion at fine scales is important for a number of regional and local level applications, including modeling of sea ice distribution, ocean-atmosphere and climate dynamics, as well as safe navigation and sea operations. In this study, we propose an optical flow and super-resolution approach to accurately estimate motion from remote sensing images at a higher spatial resolution than the original data. First, an external example learning-based super-resolution method is applied on the original images to generate higher resolution versions. Then, an optical flow approach is applied on the higher resolution images, identifying sparse correspondences and interpolating them to extract a dense motion vector field with continuous values and subpixel accuracies. Our proposed approach is successfully evaluated on passive microwave, optical, and Synthetic Aperture Radar data, proving appropriate for multi-sensor applications and different spatial resolutions. The approach estimates motion with similar or higher accuracy than the original data, while increasing the spatial resolution of up to eight times. In addition, the adopted optical flow component outperforms a state-of-the-art pattern matching method. Overall, the proposed approach results in accurate motion vectors with unprecedented spatial resolutions of up to 1.5 km for passive microwave data covering the entire Arctic and 20 m for radar data, and proves promising for numerous scientific and operational applications.

Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

Directory of Open Access Journals (Sweden)

K. Grosfeld

2007-01-01

Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

Reconstruction of late Quaternary marine and terrestrial environmental conditions of Northwest Africa and Southeast Australia : a multiple organic proxy study using marine sediments

NARCIS (Netherlands)

Alfama Lopes dos Santos, R.

2012-01-01

NW Africa and SE Australia are regions which are particularly vulnerable to climate change. In this thesis, organic proxies are used from marine sediment cores to reconstruct past environmental conditions from these areas. In sediments from NW Africa, the UK'37 showed an efficient proxy for sea

Complementary biomarker-based methods for characterising Arctic sea ice conditions: A case study comparison between multivariate analysis and the PIP25 index

Science.gov (United States)

Köseoğlu, Denizcan; Belt, Simon T.; Smik, Lukas; Yao, Haoyi; Panieri, Giuliana; Knies, Jochen

2018-02-01

The discovery of IP25 as a qualitative biomarker proxy for Arctic sea ice and subsequent introduction of the so-called PIP25 index for semi-quantitative descriptions of sea ice conditions has significantly advanced our understanding of long-term paleo Arctic sea ice conditions over the past decade. We investigated the potential for classification tree (CT) models to provide a further approach to paleo Arctic sea ice reconstruction through analysis of a suite of highly branched isoprenoid (HBI) biomarkers in ca. 200 surface sediments from the Barents Sea. Four CT models constructed using different HBI assemblages revealed IP25 and an HBI triene as the most appropriate classifiers of sea ice conditions, achieving a >90% cross-validated classification rate. Additionally, lower model performance for locations in the Marginal Ice Zone (MIZ) highlighted difficulties in characterisation of this climatically-sensitive region. CT model classification and semi-quantitative PIP25-derived estimates of spring sea ice concentration (SpSIC) for four downcore records from the region were consistent, although agreement between proxy and satellite/observational records was weaker for a core from the west Svalbard margin, likely due to the highly variable sea ice conditions. The automatic selection of appropriate biomarkers for description of sea ice conditions, quantitative model assessment, and insensitivity to the c-factor used in the calculation of the PIP25 index are key attributes of the CT approach, and we provide an initial comparative assessment between these potentially complementary methods. The CT model should be capable of generating longer-term temporal shifts in sea ice conditions for the climatically sensitive Barents Sea.

Sea ice dynamics across the Mid-Pleistocene transition in the Bering Sea.

Science.gov (United States)

Detlef, H; Belt, S T; Sosdian, S M; Smik, L; Lear, C H; Hall, I R; Cabedo-Sanz, P; Husum, K; Kender, S

2018-03-05

Sea ice and associated feedback mechanisms play an important role for both long- and short-term climate change. Our ability to predict future sea ice extent, however, hinges on a greater understanding of past sea ice dynamics. Here we investigate sea ice changes in the eastern Bering Sea prior to, across, and after the Mid-Pleistocene transition (MPT). The sea ice record, based on the Arctic sea ice biomarker IP 25 and related open water proxies from the International Ocean Discovery Program Site U1343, shows a substantial increase in sea ice extent across the MPT. The occurrence of late-glacial/deglacial sea ice maxima are consistent with sea ice/land ice hysteresis and land-glacier retreat via the temperature-precipitation feedback. We also identify interactions of sea ice with phytoplankton growth and ocean circulation patterns, which have important implications for glacial North Pacific Intermediate Water formation and potentially North Pacific abyssal carbon storage.

Religiousness and mood in the last week of life: an explorative approach based on after-death proxy interviews.

Science.gov (United States)

Braam, Arjan W; Klinkenberg, Marianne; Deeg, Dorly J H

2011-01-01

Although religiousness may, to a certain extent, be expected to alleviate emotional suffering in the last week of life, some religious beliefs might also provoke emotional distress. For the current study, after-death interviews with proxy respondents of deceased sample members of the Longitudinal Aging Study Amsterdam provided information on depressive mood and anxiety in the last week of life, as well as on the presence of a sense of peace at the approaching end of life. Proxy respondents also were asked about serious physical symptoms in the last week of life of the respondent, the respondent's cognitive decline, and their estimate of the salience of religion for the sample member. Other characteristics were derived from the last interviews with the sample members when still alive: depressive symptoms, chronic diseases, religious affiliation, church attendance, belief in Heaven, belief in Hell, and salience of religion. None of the characteristics of religiousness was significantly associated with depressive mood or anxiety, as estimated by the proxy respondent. A sense of peace, however, was predicted by higher church attendance, belief in Hell (among church-members), and the proxy's estimate of the salience of religion. It can be concluded that religiousness did not affect depressive mood or anxiety in the last week of life in the current sample. It is possible that religiousness supports a sense of peace, which may be a more-existential facet of mood and is discussed as relevant in the last phase of life and in palliative care.

Arctic Ocean sea ice cover during the penultimate glacial and the last interglacial.

Science.gov (United States)

Stein, Ruediger; Fahl, Kirsten; Gierz, Paul; Niessen, Frank; Lohmann, Gerrit

2017-08-29

Coinciding with global warming, Arctic sea ice has rapidly decreased during the last four decades and climate scenarios suggest that sea ice may completely disappear during summer within the next about 50-100 years. Here we produce Arctic sea ice biomarker proxy records for the penultimate glacial (Marine Isotope Stage 6) and the subsequent last interglacial (Marine Isotope Stage 5e). The latter is a time interval when the high latitudes were significantly warmer than today. We document that even under such warmer climate conditions, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Our proxy reconstruction of the last interglacial sea ice cover is supported by climate simulations, although some proxy data/model inconsistencies still exist. During late Marine Isotope Stage 6, polynya-type conditions occurred off the major ice sheets along the northern Barents and East Siberian continental margins, contradicting a giant Marine Isotope Stage 6 ice shelf that covered the entire Arctic Ocean.Coinciding with global warming, Arctic sea ice has rapidly decreased during the last four decades. Here, using biomarker records, the authors show that permanent sea ice was still present in the central Arctic Ocean during the last interglacial, when high latitudes were warmer than present.

Benthic hypoxia and early diagenesis in the Black Sea shelf sediments

Science.gov (United States)

Plante, Audrey; Roevros, Nathalie; Capet, Arthur; Grégoire, Marilaure; Fagel, Nathalie; Chou, Lei

2017-04-01

Marine waters of semi-enclosed seas are affected by a major environmental issue which is oxygen depletion in bottom waters. Deoxygenation is one of the most widespread man-induced consequences which can be catastrophic for living species. Between 1970 and 1990, the benthic compartment of the Black Sea underwent modifications due to the occurrence and increase of hypoxia. Indeed, these changes might cause a deterioration of the structure and functioning of the ecosystems. Nowadays, some regions, such as the north-western shelf, are still affected seasonally by this phenomenon. Within the framework of the BENTHOX project, a biogeochemical study focusing on the early diagenesis is conducted in the Black Sea. It aims (1) to obtain a better understanding of the impact of benthic hypoxia on the diagenetic pathways, (2) to contribute to a new dataset of biogeochemical measurements in the sediments including porewaters. During a cruise (Emblas II - May 2016), on board the RV Mare Nigrum, sediment cores were taken at 4 stations on the Ukrainian shelf. Porewaters were extracted on board the ship using Rhizon technique under N2 atmosphere and will be analyzed for dissolved nutrients and major ions. In addition, sediments were sliced and will be determined for major solid phases and trace element contents. A multi-proxies (biological, sedimentological, mineralogical and geochemical) approach will be used to identify the hypoxic events and to reconstruct the history of bottom hypoxia. The results obtained will be presented and discussed with emphasis on the first outcomes and the major biogeochemical processes involved in the early diagenesis.

A statistical-dynamical modeling approach for the simulation of local paleo proxy records using GCM output

Energy Technology Data Exchange (ETDEWEB)

Reichert, B.K.; Bengtsson, L. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Aakesson, O. [Sveriges Meteorologiska och Hydrologiska Inst., Norrkoeping (Sweden)

1998-08-01

Recent proxy data obtained from ice core measurements, dendrochronology and valley glaciers provide important information on the evolution of the regional or local climate. General circulation models integrated over a long period of time could help to understand the (external and internal) forcing mechanisms of natural climate variability. For a systematic interpretation of in situ paleo proxy records, a combined method of dynamical and statistical modeling is proposed. Local 'paleo records' can be simulated from GCM output by first undertaking a model-consistent statistical downscaling and then using a process-based forward modeling approach to obtain the behavior of valley glaciers and the growth of trees under specific conditions. The simulated records can be compared to actual proxy records in order to investigate whether e.g. the response of glaciers to climatic change can be reproduced by models and to what extent climate variability obtained from proxy records (with the main focus on the last millennium) can be represented. For statistical downscaling to local weather conditions, a multiple linear forward regression model is used. Daily sets of observed weather station data and various large-scale predictors at 7 pressure levels obtained from ECMWF reanalyses are used for development of the model. Daily data give the closest and most robust relationships due to the strong dependence on individual synoptic-scale patterns. For some local variables, the performance of the model can be further increased by developing seasonal specific statistical relationships. The model is validated using both independent and restricted predictor data sets. The model is applied to a long integration of a mixed layer GCM experiment simulating pre-industrial climate variability. The dynamical-statistical local GCM output within a region around Nigardsbreen glacier, Norway is compared to nearby observed station data for the period 1868-1993. Patterns of observed

Integrating out the Dirac sea

International Nuclear Information System (INIS)

Karbstein, Felix

2009-01-01

We introduce a new method for dealing with fermionic quantum field theories amenable to a mean-field-type approximation. In this work we focus on the relativistic Hartree approximation. Our aim is to integrate out the Dirac sea and derive a no-sea effective theory'' with positive energy single particle states only. As the derivation of the no-sea effective theory involves only standard Feynman diagrams, our approach is quite general and not restricted to particular space-time dimensions. We develop and illustrate the approach in the ''large N'' limit of the Gross-Neveu model family in 1+1 dimensions. As the Gross-Neveu model has been intensely studied and several analytical solutions are known for this model, it is an ideal testing ground for our no-sea effective theory approach. The chiral Gross-Neveu model, also referred to as 1+1 dimensional Nambu-Jona-Lasinio model, turns out to be of particular interest. In this case, we explicitly derive a consistent effective theory featuring both elementary ''π meson'' fields and (positive energy) ''quark'' fields, starting from a purely fermionic quantum field theory. In the second part of this work, we apply our approach to the Walecka model in 1+1 and 3+1 dimensions. As the Dirac sea caused considerable difficulties in attempts to base nuclear physics on field theoretic models like the Walecka model, mean-field calculations were typically done without the sea. We confront several of these mean-field theory results with our no-sea effective theory approach. The potential of our approach is twofold. While the no-sea effective theory can be utilized to provide new analytical insights in particular parameter regimes, it also sheds new light on more fundamental issues as the explicit emergence of effective, Dirac-sea induced multi-fermion interactions in an effective theory with positive energy states only. (orig.)

Inferring climate variability from skewed proxy records

Science.gov (United States)

Emile-Geay, J.; Tingley, M.

2013-12-01

Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and

A Multi-Model Approach for System Diagnosis

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Poulsen, Niels Kjølstad; Bækgaard, Mikkel Ask Buur

2007-01-01

A multi-model approach for system diagnosis is presented in this paper. The relation with fault diagnosis as well as performance validation is considered. The approach is based on testing a number of pre-described models and find which one is the best. It is based on an active approach......,i.e. an auxiliary input to the system is applied. The multi-model approach is applied on a wind turbine system....

Atmospheric forcing of decadal Baltic Sea level variability in the last 200 years. A statistical analysis

Energy Technology Data Exchange (ETDEWEB)

Huenicke, B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Kuestenforschung

2008-11-06

This study aims at the estimation of the impact of different atmospheric factors on the past sealevel variations (up to 200 years) in the Baltic Sea by statistically analysing the relationship between Baltic Sea level records and observational and proxy-based reconstructed climatic data sets. The focus lies on the identification and possible quantification of the contribution of sealevel pressure (wind), air-temperature and precipitation to the low-frequency (decadal and multi-decadal) variability of Baltic Sea level. It is known that the wind forcing is the main factor explaining average Baltic Sea level variability at inter-annual to decadal timescales, especially in wintertime. In this thesis it is statistically estimated to what extent other regional climate factors contribute to the spatially heterogeneous Baltic Sea level variations around the isostatic trend at multi-decadal timescales. Although the statistical analysis cannot be completely conclusive, as the potential climate drivers are all statistically interrelated to some degree, the results indicate that precipitation should be taken into account as an explanatory variable for sea-level variations. On the one hand it has been detected that the amplitude of the annual cycle of Baltic Sea level has increased throughout the 20th century and precipitation seems to be the only factor among those analysed (wind through SLP field, barometric effect, temperature and precipitation) that can account for this evolution. On the other hand, precipitation increases the ability to hindcast inter-annual variations of sea level in some regions and seasons, especially in the Southern Baltic in summertime. The mechanism by which precipitation exerts its influence on Baltic Sea level is not ascertained in this statistical analysis due to the lack of long salinity time series. This result, however, represents a working hypothesis that can be confirmed or disproved by long simulations of the Baltic Sea system - ocean

Comparing Apples to Apples: Paleoclimate Model-Data comparison via Proxy System Modeling

Science.gov (United States)

Dee, Sylvia; Emile-Geay, Julien; Evans, Michael; Noone, David

2014-05-01

under assumed dating uncertainties. We demonstrate the utility of the PSM framework with an integrative multi-PSM simulation. An intermediate-complexity AGCM with isotope physics (SPEEDY-IER, (Molteni, 2003, Dee et al., in prep)) is used to simulate the isotope hydrology and atmospheric response to SSTs derived from the LM PMIP3 integration of the CCSM4 model (Landrum et al., 2012). Relevant dynamical and isotope variables are then used to drive PSMs, emulating a realistic multiproxy network (Emile-Geay et al., 2013). We then ask the following question: given our best knowledge of proxy systems, what aspects of GCM behavior may be validated, and with what uncertainties? We approach this question via a three-tiered 'perfect model' study. A random realization of the simulated proxy data (hereafter 'PaleoObs') is used as a benchmark in the following comparisons: (1) AGCM output (without isotopes) vs. PaleoObs; (2) AGCM output (with isotopes) vs. PaleoObs; (3) coupled AGCM-PSM-simulated proxy ensemble vs. PaleoObs. Enhancing model-data comparison using PSMs highlights uncertainties that may arise from ignoring non-linearities in proxy-climate relationships, or the presence of age uncertainties (as is most typically done is paleoclimate model-data intercomparison). Companion experiments leveraging the 3 sub-model compartmentalization of PSMs allows us to quantify the contribution of each sub-system to the observed model-data discrepancies. We discuss potential repercussions for model-data comparison and implications for validating predictive climate models using paleodata. References Braconnot, P., Harrison, S. P., Kageyama, M., Bartlein, P. J., Masson-Delmotte, V., Abe-Ouchi, A., Otto-Bliesner, B., Zhao, Y., 06 2012. Evaluation of climate models using palaeoclimatic data. Nature Clim. Change 2 (6), 417-424. URL http://dx.doi.org/10.1038/nclimate1456 Emile-Geay, J., Cobb, K. M., Mann, M. E., Wittenberg, A. T., Apr 01 2013. Estimating central equatorial pacific sst

Elephant overflows: Multi-annual variability in Weddell Sea Deep Water driven by surface forcing

Science.gov (United States)

Meijers, Andrew; Meredith, Michael; Abrahamsen, Povl; Naviera-Garabato, Alberto; Ángel Morales Maqueda, Miguel; Polzin, Kurt

2015-04-01

The volume of the deepest and densest water mass in Drake Passage, Lower Weddell Sea Deep Water (LWSDW), is shown to have been decreasing over the last 20 years of observations, with an associated reduction in density driven by freshening. Superimposed on this long term trend is a multi-annual oscillation with a period of 3-5 years. This variability only appears in Drake Passage; observations in the east of the Scotia Sea show a similar long term trend, but with no apparent multi-annual variability. Clues as to the source of this variability may be found on the continental slope at approximately 1000 m immediately north of Elephant Island on the northern tip of the Antarctic Peninsula. Here there is an intermittent westward flowing cold/fresh slope current whose volume and properties are strongly correlated with the LWSDW multi-annual variability, although leading the LWSDW by around one year. As the slope current and LWSDW are separated from each other both geographically and in water mass characteristics, their co-variability implies that they are responding to a common forcing, while the lag between deep LWSDW and shallow slope current provides information on the timescale of this response. A newly available high resolution temperature and salinity multi-year time series from the Elephant Island slope at 1000 m is compared with reanalysis and model derived surface fluxes, sea ice extent and wind stress. We find that there are strong positive relationships between the surface wind stress and heat flux over the shelf at the tip of the Antarctic Peninsula and the properties of the slope current at 1000 m on seasonal to annual timescales. We use tracer release experiments in the Southern Ocean State Estimate (SOSE) model to investigate the lag between the slope current and LWSDW timeseries and hypothesise that the observed multi-annual variability in both water masses is driven by surface forcing over the shelf and the overflow of modified water from the slope in

Environmental changes in the central Baltic Sea during the past 1000 years: inferences from sedimentary records, hydrography and climate

Directory of Open Access Journals (Sweden)

Jan Bartholdy

2008-03-01

Full Text Available Short sediment cores from the eastern Gotland Basin were investigated using a multi-proxy approach in order to reconstruct the environmental conditions of the area during the past 1000 years. Sediment data and facies were discussed in relation to hydrographic features (salinity, oxygen and climate change. During the medieval warm period (MWP, from about 900 to 1250 AD, the hydrographic and environmental conditions were similar to those of the present time (modern warm period, since about 1850: a temporally stable halocline, caused by regular saline water inflows from the North Sea, prevents vertical mixing and leads to bottom water anoxia and the deposition of laminated, organic-rich sapropels. During the period from about 1250 to 1850, referred to as the cold phase (including the Little Ice Age, the environmental conditions of the central Baltic Sea were distinctly different: the lower salinity, resulting from reduced North Sea water inflows, allowed vertical convection of the water column and long-term stable ventilation of the sea bed (oxic stage. Both the productivity of the planktonic ecosystem as well as the preservation of organic matter in the sediments improved during the warm periods. The anthropogenic impact can be identified within the recent laminated sequence by a temporal reconstruction of pollutant deposition. Our findings imply a climate-change driven shift in the environmental conditions and the ecosystem of the Baltic from the north to the south and back to the north.

Climate proxy data as groundwater tracers in regional flow systems

Science.gov (United States)

Clark, J. F.; Morrissey, S. K.; Stute, M.

2008-05-01

The isotopic and chemical signatures of groundwater reflect local climate conditions. By systematically analyzing groundwater and determining their hydrologic setting, records of past climates can be constructed. Because of their chemistries and relatively uncomplicated source functions, dissolved noble gases have yielded reliable records of continental temperatures for the last 30,000 to 50,000 years. Variations in the stable isotope compositions of groundwater due to long term climate changes have also been documented over these time scales. Because glacial - interglacial climate changes are relatively well known, these climate proxies can be used as "stratigraphic" markers within flow systems and used to distinguish groundwaters that have recharged during the Holocene from those recharged during the last glacial period, important time scales for distinguishing regional and local flow systems in many aquifers. In southern Georgia, the climate proxy tracers were able to identify leakage from surface aquifers into the Upper Floridan aquifer in areas previously thought to be confined. In south Florida, the transition between Holocene and glacial signatures in the Upper Floridan aquifer occurs mid-way between the recharge area and Lake Okeechobee. Down gradient of the lake, the proxies are uniform, indicating recharge during the last glacial period. Furthermore, there is no evidence for leakage from the shallow aquifers into the Upper Floridan. In the Lower Floridan, the climate proxies indicate that the saline water entered the aquifer after sea level rose to its present level.

Calcium isotopic composition of high-latitude proxy carrier Neogloboquadrina pachyderma (sin.

Directory of Open Access Journals (Sweden)

A. Eisenhauer

2009-01-01

Full Text Available The accurate reconstruction of sea surface temperature (SST history in climate-sensitive regions (e.g. tropical and polar oceans became a challenging task in palaeoceanographic research. Biogenic shell carbonate SST proxies successfully developed for tropical regions often fail in cool water environments. Their major regional shortcomings and the cryptic diversity now found within the major high latitude proxy carrier Neogloboquadrina pachyderma (sin. highlight an urgent need to explore complementary SST proxies for these cool-water regions. Here we incorporate the genetic component into a calibration study of a new SST proxy for the high latitudes. We found that the calcium isotopic composition (δ44/40Ca of calcite from genotyped net catches and core-top samples of the planktonic foraminifera Neogloboquadrina pachyderma (sin. is related to temperature and unaffected by genetic variations. The temperature sensitivity has been found to be 0.17 (±0.02‰ per 1°C, highlighting its potential for downcore applications in open marine cool-water environments. Our results further indicate that in extreme polar environments, below a critical threshold temperature of 2.0 (±0.5°C associated with salinities below 33.0 (±0.5‰, a prominent shift in biomineralization affects the δ44/40Ca of genotyped and core-top N. pachyderma (sin., becoming insensitive to temperature. These findings highlight the need of more systematic calibration studies on single planktonic foraminiferal species in order to unravel species-specific factors influencing the temperature sensitivity of Ca isotope fractionation and to validate the proxies' applicability.

Mechanistic controls on diverse fates of terrestrial organic components in the East China Sea

Science.gov (United States)

Zhu, Chun; Wagner, Thomas; Talbot, Helen M.; Weijers, Johan W. H.; Pan, Jian-Ming; Pancost, Richard D.

2013-09-01

Terrestrial carbon transferred from the land to sea is a critical component of the global carbon cycle. A range of geochemical proxies has been developed to fingerprint the fate of terrestrial organic matter (TOM) in marine sediments. However, discrepancies among different proxies limit our ability to quantify and interpret the terrestrial signals in marine sediments, with consequences for the investigation of both the modern carbon cycle and past environmental change. To mechanistically understand these discrepancies, we examined the distributions of a range of terrestrial proxies and their aquatic counterparts (i.e. marine proxies) in the Yangtze river-East China Sea (YR-ECS) shelf system, where TOM experiences extensive modification during transport and burial. TOM proxies in the YR-ECS system collectively fit a power-law model but with distinct attenuation rates (the a∗ values) for individual molecular proxy groups. Among a range of TOM proxies, the modeled a∗ values decrease in the order: soil-marker BHPs > triterpenols > lignin > HMW n-alkanols > branched GDGTs > HMW n-alkanes for biomarkers; and Rsoil > BIT > %TOMiso for proxies tracing %TOM. Rapid loss of TOM components through dissociation in the narrow estuary, followed by oxidation over the wide open shelf, are best described by power curves. Inherent chemical reactivity (i.e. the number of functional groups), responses to hydraulic sorting, and in situ production regulate the individual attenuation rates. Of them, chemical reactivity plays the most important role on proxy behavior, supported by a strong correlation between a∗ values and standard molal Gibbs energies. Both, physical protection and chemical reactivity fundamentally control the overall behavior of TOM components, with the relative importance being setting-dependant: The former is relatively important in the estuary, whereas the later is the primary control over the open shelf. Moreover, regional variation of different marine

A multiple-proxy approach to understanding rapid Holocene climate change in Southeast Greenland

Science.gov (United States)

Davin, S. H.; Bradley, R. S.; Balascio, N. L.; de Wet, G.

2012-12-01

The susceptibility of the Arctic to climate change has made it an excellent workshop for paleoclimatological research. Although there have been previous studies concerning climate variability carried out in the Arctic, there remains a critical dearth of knowledge due the limited number of high-resolution Holocene climate-proxy records available from this region. This gap skews our understanding of observed and predicted climate change, and fuels uncertainty both in the realms of science and policy. This study takes a comprehensive approach to tracking Holocene climate variability in the vicinity of Tasiilaq, Southeast Greenland using a ~5.6 m sediment core from Lower Sermilik Lake. An age-depth model for the core has been established using 8 radiocarbon dates, the oldest of which was taken at 4 m down core and has been been dated to approximately 6.2 kyr BP. The bottom meter of the core below the final radiocarbon date contains a transition from cobbles and coarse sand to organic-rich laminations, indicating the termination of direct glacial influence and therefore likely marking the end of the last glacial period in this region. The remainder of the core is similarly organic-rich, with light-to-dark brown laminations ranging from 0.5 -1 cm in thickness and riddled with turbidites. Using this core in tandem with findings from an on-site assessment of the geomorphic history of the locale we attempt to assess and infer the rapid climatic shifts associated with the Holocene on a sub-centennial scale. Such changes include the termination of the last glacial period, the Mid-Holocene Climatic Optimum, the Neoglacial Period, the Medieval Climatic Optimum, and the Little Ice Age. A multiple proxy approach including magnetic susceptibility, bulk organic geochemistry, elemental profiles acquired by XRF scanning, grain-size, and spectral data will be used to characterize the sediment and infer paleoclimate conditions. Additionally, percent biogenic silica by weight has been

On Sea Ice Characterisation By Multi-Frequency SAR

Science.gov (United States)

Grahn, Jakob; Brekke, Camilla; Eltoft, Torbjorn; Holt, Benjamin

2013-12-01

By means of polarimetric target decomposition, quad-pol SAR data of sea ice is analysed at two frequency bands. In particular, the non negative eigenvalue decomposition (NNED) is applied on L- and C-band NASA/JPL AIR- SAR data acquired over the Beaufort sea in 2004. The de- composition separates the scattered radar signal into three types, dominated by double, volume and single bounce scattering respectively. Using ground truth derived from RADARSAT-1 and meteorological data, we investigate how the different frequency bands compare in terms of these scattering types. The ground truth contains multi year ice and three types of first year ice of different age and thickness. We find that C-band yields a higher scattered intensity in most ice and scattering types, as well as a more homogeneous intensity. L-band on the other hand yields more pronounced deformation features, such as ridges. The mean intensity contrast between the two thinnest ice types is highest in the double scattering component of C- band, although the contrast of the total signal is greater in L-band. This may indicate that the choice of polarimetric parameters is important for discriminating thin ice types.

Mixtures of Gaussians for uncertainty description in bivariate latent heat flux proxies

NARCIS (Netherlands)

Wójcik, R.; Troch, P.A.A.; Stricker, J.N.M.; Torfs, P.J.J.F.

2006-01-01

This paper proposes a new probabilistic approach for describing uncertainty in the ensembles of latent heat flux proxies. The proxies are obtained from hourly Bowen ratio and satellite-derived measurements, respectively, at several locations in the southern Great Plains region in the United States.

Here be web proxies

DEFF Research Database (Denmark)

Weaver, Nicholas; Kreibich, Christian; Dam, Martin

2014-01-01

,000 clients that include a novel proxy location technique based on traceroutes of the responses to TCP connection establishment requests, which provides additional clues regarding the purpose of the identified web proxies. Overall, we see 14% of Netalyzr-analyzed clients with results that suggest the presence...... of web proxies....

A Late Pleistocene sea level stack

OpenAIRE

Spratt Rachel M; Lisiecki Lorraine E

2016-01-01

Late Pleistocene sea level has been reconstructed from ocean sediment core data using a wide variety of proxies and models. However, the accuracy of individual reconstructions is limited by measurement error, local variations in salinity and temperature, and assumptions particular to each technique. Here we present a sea level stack (average) which increases the signal-to-noise ratio of individual reconstructions. Specifically, we perform principal componen...

Jemen - the Proxy War

Directory of Open Access Journals (Sweden)

Magdalena El Ghamari

2015-12-01

Full Text Available The military operation in Yemen is significant departure from Saudi Arabia's foreign policy tradition and customs. Riyadh has always relied on three strategies to pursue its interests abroad: wealth, establish a global network and muslim education and diplomacy and meadiation. The term "proxy war" has experienced a new popularity in stories on the Middle East. A proxy war is two opposing countries avoiding direct war, and instead supporting combatants that serve their interests. In some occasions, one country is a direct combatant whilst the other supporting its enemy. Various news sources began using the term to describe the conflict in Yemen immediately, as if on cue, after Saudi Arabia launched its bombing campaign against Houthi targets in Yemen on 25 March 2015. This is the reason, why author try to answer for following questions: Is the Yemen Conflict Devolves into Proxy War? and Who's fighting whom in Yemen's proxy war?" Research area includes the problem of proxy war in the Middle East. For sure, the real problem of proxy war must begin with the fact that the United States and its NATO allies opened the floodgates for regional proxy wars by the two major wars for regime change: in Iraq and Libya. Those two destabilising wars provided opportunities and motives for Sunni states across the Middle East to pursue their own sectarian and political power objectives through "proxy war".

Conceptualizing strategic environmental assessment: Principles, approaches and research directions

International Nuclear Information System (INIS)

Noble, Bram; Nwanekezie, Kelechi

2017-01-01

Increasing emphasis has been placed in recent years on transitioning strategic environmental assessment (SEA) away from its environmental impact assessment (EIA) roots. Scholars have argued the need to conceptualize SEA as a process designed to facilitate strategic thinking, thus enabling transitions toward sustainability. The practice of SEA, however, remains deeply rooted in the EIA tradition and scholars and practitioners often appear divided on the nature and purpose of SEA. This paper revisits the strategic principles of SEA and conceptualizes SEA as a multi-faceted and multi-dimensional assessment process. It is suggested that SEA can be conceptualized as series of approaches operating along a spectrum from less to more strategic – from impact assessment-based to strategy-based – with each approach to SEA differentiated by the specific objectives of SEA application and the extent to which strategic principles are reflected in its design and implementation. Advancing the effectiveness of SEA requires a continued research agenda focused on improving the traditional SEA approach, as a tool to assess the impacts of policies, plans and programs (PPPs). Realizing the full potential of SEA, however, requires a new research agenda — one focused on the development and testing of a deliberative governance approach to SEA that can facilitate strategic innovations in PPP formulation and drive transitions in short-term policy and initiatives based on longer-term thinking. - Highlights: • SEA facilitates strategic thinking, enabling transitions toward sustainability. • SEA is conceptualized as a spectrum of approaches, from IA-based to strategy-based. • Each approach variably emphasizes strategic principles in its design and practice. • There is no one conceptualization of SEA that is best, SEA is fit for PPP purpose. • Research is needed to advance SEA to facilitate strategic PPP transformations.

Conceptualizing strategic environmental assessment: Principles, approaches and research directions

Energy Technology Data Exchange (ETDEWEB)

Noble, Bram, E-mail: b.noble@usask.ca [Department of Geography and Planning, and School of Environment and Sustainability, University of Saskatchewan, 117 Science Place, Saskatoon, Saskatchewan S7N 5A5 (Canada); Nwanekezie, Kelechi [Department of Geography and Planning, University of Saskatchewan, 117 Science Place, Saskatoon, Saskatchewan S7N 5A5 (Canada)

2017-01-15

Increasing emphasis has been placed in recent years on transitioning strategic environmental assessment (SEA) away from its environmental impact assessment (EIA) roots. Scholars have argued the need to conceptualize SEA as a process designed to facilitate strategic thinking, thus enabling transitions toward sustainability. The practice of SEA, however, remains deeply rooted in the EIA tradition and scholars and practitioners often appear divided on the nature and purpose of SEA. This paper revisits the strategic principles of SEA and conceptualizes SEA as a multi-faceted and multi-dimensional assessment process. It is suggested that SEA can be conceptualized as series of approaches operating along a spectrum from less to more strategic – from impact assessment-based to strategy-based – with each approach to SEA differentiated by the specific objectives of SEA application and the extent to which strategic principles are reflected in its design and implementation. Advancing the effectiveness of SEA requires a continued research agenda focused on improving the traditional SEA approach, as a tool to assess the impacts of policies, plans and programs (PPPs). Realizing the full potential of SEA, however, requires a new research agenda — one focused on the development and testing of a deliberative governance approach to SEA that can facilitate strategic innovations in PPP formulation and drive transitions in short-term policy and initiatives based on longer-term thinking. - Highlights: • SEA facilitates strategic thinking, enabling transitions toward sustainability. • SEA is conceptualized as a spectrum of approaches, from IA-based to strategy-based. • Each approach variably emphasizes strategic principles in its design and practice. • There is no one conceptualization of SEA that is best, SEA is fit for PPP purpose. • Research is needed to advance SEA to facilitate strategic PPP transformations.

Analyses of Sea Surface Height, Bottom Pressure and Acoustic Travel Time in the Japan/East Sea

National Research Council Canada - National Science Library

Xu, Yongsheng

2006-01-01

...) was deployed in the southwestern JES for two years, from June 1999 to July 2001. The PIESs recorded hourly vertical acoustic travel time and pressure, which are respectively good proxies of baroclinic and barotropic sea level variability...

Mid-Pliocene to Early Pleistocene land and sea surface temperature history of NW Australia based on organic geochemical proxies

Science.gov (United States)

Smith, R. A.; Castañeda, I. S.; Henderiks, J.; Christensen, B. A.; De Vleeschouwer, D.; Renema, W.; Groeneveld, J.; Bogus, K.; Gallagher, S. J.; Fulthorpe, C.; Expedition 356 Scientists, I.

2017-12-01

IODP Expedition 356 Site U1463 is located off the coast of NW Australia, and is sensitive to Indonesian Throughflow (ITF) variability. The ITF is a critical ocean gateway that affects global thermohaline circulation, and regulates the movement of water from the Pacific Ocean into the Indian Ocean. However, despite its importance to the global climate system, few SST reconstructions exist for this region that span the Plio-Pleistocene. Here we investigate both the land and sea-surface temperature (SST) history of NW Australia to constrain ITF variability across the Plio-Pleistocene interval. We apply multiple organic geochemical proxies to this site from 3.4-2.6 Ma, which includes the mid-Pliocene warm period, characterized by slightly higher (2-3°C) global temperatures and similar CO2 concentrations to modern values (e.g. Badger et al. 2013; Bartoli et al., 2011; Dowsett et al., 2009; Hönisch et al., 2009; Pagani et al. 2009; Raymo et al., 1996). SST was reconstructed using TEX86, based on isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs), and the long-chain diol index (LDI), based on the ratio of diols produced by marine diatoms (Rampen et al., 2012). The Uk'37 index, based on long-chain ketones, was analyzed but cannot be applied as a SST proxy at this site due to the influence of coastal alkenone producers. Additionally, a continental air temperature record was developed using the MBT'5ME proxy, based on branched GDGTs (De Jonge et al., 2014; Weijers et al., 2007). We find that TEX86, LDI and MBT'5Me exhibit similar trends and show relatively warm and stable temperatures from 3.5-2.4 Ma followed by a gradual cooling of 3-4°C from 2.4-1.5 Ma. This cooling corresponds with an arid interval previously identified on the same core by Christensen et al. (2017). Furthermore, we find that the TEX86 record agrees closely with the LR04 global benthic δ18O stack (Lisiecki and Raymo, 2005) and captures glacial/interglacial periods including Marine Isotope Stage

Bacterial communities from Arctic seasonal sea ice are more compositionally variable than those from multi-year sea ice.

Science.gov (United States)

Hatam, Ido; Lange, Benjamin; Beckers, Justin; Haas, Christian; Lanoil, Brian

2016-10-01

Arctic sea ice can be classified into two types: seasonal ice (first-year ice, FYI) and multi-year ice (MYI). Despite striking differences in the physical and chemical characteristics of FYI and MYI, and the key role sea ice bacteria play in biogeochemical cycles of the Arctic Ocean, there are a limited number of studies comparing the bacterial communities from these two ice types. Here, we compare the membership and composition of bacterial communities from FYI and MYI sampled north of Ellesmere Island, Canada. Our results show that communities from both ice types were dominated by similar class-level phylogenetic groups. However, at the operational taxonomic unit (OTU) level, communities from MYI and FYI differed in both membership and composition. Communities from MYI sites had consistent structure, with similar membership (presence/absence) and composition (OTU abundance) independent of location and year of sample. By contrast, communities from FYI were more variable. Although FYI bacterial communities from different locations and different years shared similar membership, they varied significantly in composition. Should these findings apply to sea ice across the Arctic, we predict increased compositional variability in sea ice bacterial communities resulting from the ongoing transition from predominantly MYI to FYI, which may impact nutrient dynamics in the Arctic Ocean.

A multi-disciplinary approach for the integrated assessment of multiple risks in delta areas.

Science.gov (United States)

Sperotto, Anna; Torresan, Silvia; Critto, Andrea; Marcomini, Antonio

2016-04-01

The assessment of climate change related risks is notoriously difficult due to the complex and uncertain combinations of hazardous events that might happen, the multiplicity of physical processes involved, the continuous changes and interactions of environmental and socio-economic systems. One important challenge lies in predicting and modelling cascades of natural and man -made hazard events which can be triggered by climate change, encompassing different spatial and temporal scales. Another regard the potentially difficult integration of environmental, social and economic disciplines in the multi-risk concept. Finally, the effective interaction between scientists and stakeholders is essential to ensure that multi-risk knowledge is translated into efficient adaptation and management strategies. The assessment is even more complex at the scale of deltaic systems which are particularly vulnerable to global environmental changes, due to the fragile equilibrium between the presence of valuable natural ecosystems and relevant economic activities. Improving our capacity to assess the combined effects of multiple hazards (e.g. sea-level rise, storm surges, reduction in sediment load, local subsidence, saltwater intrusion) is therefore essential to identify timely opportunities for adaptation. A holistic multi-risk approach is here proposed to integrate terminology, metrics and methodologies from different research fields (i.e. environmental, social and economic sciences) thus creating shared knowledge areas to advance multi risk assessment and management in delta regions. A first testing of the approach, including the application of Bayesian network analysis for the assessment of impacts of climate change on key natural systems (e.g. wetlands, protected areas, beaches) and socio-economic activities (e.g. agriculture, tourism), is applied in the Po river delta in Northern Italy. The approach is based on a bottom-up process involving local stakeholders early in different

Integrating out the Dirac sea

Energy Technology Data Exchange (ETDEWEB)

Karbstein, Felix

2009-07-08

We introduce a new method for dealing with fermionic quantum field theories amenable to a mean-field-type approximation. In this work we focus on the relativistic Hartree approximation. Our aim is to integrate out the Dirac sea and derive a no-sea effective theory'' with positive energy single particle states only. As the derivation of the no-sea effective theory involves only standard Feynman diagrams, our approach is quite general and not restricted to particular space-time dimensions. We develop and illustrate the approach in the ''large N'' limit of the Gross-Neveu model family in 1+1 dimensions. As the Gross-Neveu model has been intensely studied and several analytical solutions are known for this model, it is an ideal testing ground for our no-sea effective theory approach. The chiral Gross-Neveu model, also referred to as 1+1 dimensional Nambu-Jona-Lasinio model, turns out to be of particular interest. In this case, we explicitly derive a consistent effective theory featuring both elementary ''{pi} meson'' fields and (positive energy) ''quark'' fields, starting from a purely fermionic quantum field theory. In the second part of this work, we apply our approach to the Walecka model in 1+1 and 3+1 dimensions. As the Dirac sea caused considerable difficulties in attempts to base nuclear physics on field theoretic models like the Walecka model, mean-field calculations were typically done without the sea. We confront several of these mean-field theory results with our no-sea effective theory approach. The potential of our approach is twofold. While the no-sea effective theory can be utilized to provide new analytical insights in particular parameter regimes, it also sheds new light on more fundamental issues as the explicit emergence of effective, Dirac-sea induced multi-fermion interactions in an effective theory with positive energy states only. (orig.)

Power magnetic devices a multi-objective design approach

CERN Document Server

Sudhoff, Scott D

2014-01-01

Presents a multi-objective design approach to the many power magnetic devices in use today Power Magnetic Devices: A Multi-Objective Design Approach addresses the design of power magnetic devices-including inductors, transformers, electromagnets, and rotating electric machinery-using a structured design approach based on formal single- and multi-objective optimization. The book opens with a discussion of evolutionary-computing-based optimization. Magnetic analysis techniques useful to the design of all the devices considered in the book are then set forth. This material is then used for ind

Shoreline change after 12 years of tsunami in Banda Aceh, Indonesia: a multi-resolution, multi-temporal satellite data and GIS approach

Science.gov (United States)

Sugianto, S.; Heriansyah; Darusman; Rusdi, M.; Karim, A.

2018-04-01

The Indian Ocean Tsunami event on the 26 December 2004 has caused severe damage of some shorelines in Banda Aceh City, Indonesia. Tracing back the impact can be seen using remote sensing data combined with GIS. The approach is incorporated with image processing to analyze the extent of shoreline changes with multi-temporal data after 12 years of tsunami. This study demonstrates multi-resolution and multi-temporal satellite images of QuickBird and IKONOS to demarcate the shoreline of Banda Aceh shoreline from before and after tsunami. The research has demonstrated a significant change to the shoreline in the form of abrasion between 2004 and 2005 from few meters to hundred meters’ change. The change between 2004 and 2011 has not returned to the previous stage of shoreline before the tsunami, considered post tsunami impact. The abrasion occurs between 18.3 to 194.93 meters. Further, the change in 2009-2011 shows slowly change of shoreline of Banda Aceh, considered without impact of tsunami e.g. abrasion caused by ocean waves that erode the coast and on specific areas accretion occurs caused by sediment carried by the river flow into the sea near the shoreline of the study area.

A System of Systems Approach to Integrating Global Sea Level Change Application Programs

Science.gov (United States)

Bambachus, M. J.; Foster, R. S.; Powell, C.; Cole, M.

2005-12-01

The global sea level change application community has numerous disparate models used to make predications over various regional and temporal scales. These models have typically been focused on limited sets of data and optimized for specific areas or questions of interest. Increasingly, decision makers at the national, international, and local/regional levels require access to these application data models and want to be able to integrate large disparate data sets, with new ubiquitous sensor data, and use these data across models from multiple sources. These requirements will force the Global Sea Level Change application community to take a new system-of-systems approach to their programs. We present a new technical architecture approach to the global sea level change program that provides external access to the vast stores of global sea level change data, provides a collaboration forum for the discussion and visualization of data, and provides a simulation environment to evaluate decisions. This architectural approach will provide the tools to support multi-disciplinary decision making. A conceptual system of systems approach is needed to address questions around the multiple approaches to tracking and predicting Sea Level Change. A systems of systems approach would include (1) a forum of data providers, modelers, and users, (2) a service oriented architecture including interoperable web services with a backbone of Grid computing capability, and (3) discovery and access functionality to the information developed through this structure. Each of these three areas would be clearly designed to maximize communication, data use for decision making and flexibility and extensibility for evolution of technology and requirements. In contemplating a system-of-systems approach, it is important to highlight common understanding and coordination as foundational to success across the multiple systems. The workflow of science in different applications is often conceptually similar

An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

Science.gov (United States)

Steen, Laura E.; Ide, Robert F.; Van Zante, Judith Foss

2017-01-01

The Icing Research Tunnel at NASA Glenn has recently switched to from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to perform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collection efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison.

Mid-Piacensian mean annual sea surface temperature: an analysis for data-model comparisons

Science.gov (United States)

Dowsett, Harry J.; Robinson, Marci M.; Foley, Kevin M.; Stoll, Danielle K.

2010-01-01

Numerical models of the global climate system are the primary tools used to understand and project climate disruptions in the form of future global warming. The Pliocene has been identified as the closest, albeit imperfect, analog to climate conditions expected for the end of this century, making an independent data set of Pliocene conditions necessary for ground truthing model results. Because most climate model output is produced in the form ofmean annual conditions, we present a derivative of the USGS PRISM3 Global Climate Reconstruction which integrates multiple proxies of sea surface temperature (SST) into single surface temperature anomalies. We analyze temperature estimates from faunal and floral assemblage data,Mg/Ca values and alkenone unsaturation indices to arrive at a single mean annual SST anomaly (Pliocene minus modern) best describing each PRISM site, understanding that multiple proxies should not necessarily show concordance. The power of themultiple proxy approach lies within its diversity, as no two proxies measure the same environmental variable. This data set can be used to verify climate model output, to serve as a starting point for model inter-comparisons, and for quantifying uncertainty in Pliocene model prediction in perturbed physics ensembles.

Changes in atmospheric variability in a glacial climate and the impacts on proxy data: a model intercomparison

Directory of Open Access Journals (Sweden)

F. S. R. Pausata

2009-09-01

Full Text Available Using four different climate models, we investigate sea level pressure variability in the extratropical North Atlantic in the preindustrial climate (1750 AD and at the Last Glacial Maximum (LGM, 21 kyrs before present in order to understand how changes in atmospheric circulation can affect signals recorded in climate proxies.

In general, the models exhibit a significant reduction in interannual variance of sea level pressure at the LGM compared to pre-industrial simulations and this reduction is concentrated in winter. For the preindustrial climate, all models feature a similar leading mode of sea level pressure variability that resembles the leading mode of variability in the instrumental record: the North Atlantic Oscillation (NAO. In contrast, the leading mode of sea level pressure variability at the LGM is model dependent, but in each model different from that in the preindustrial climate. In each model, the leading (NAO-like mode of variability explains a smaller fraction of the variance and also less absolute variance at the LGM than in the preindustrial climate.

The models show that the relationship between atmospheric variability and surface climate (temperature and precipitation variability change in different climates. Results are model-specific, but indicate that proxy signals at the LGM may be misinterpreted if changes in the spatial pattern and seasonality of surface climate variability are not taken into account.

A first look at the ACER-SST dataset: Mapping the spatio-temporal variability of sea-surface temperatures in the last Glacial and the Holocene

Science.gov (United States)

Rehfeld, Kira; Laepple, Thomas; Bassinot, Franck; Daniau, Anne-Laure; Desprat, Stéphanie; Kim, Jung-Hyun; Fernanda Sánchez-Goñi, Maria; Harrison, Sandy

2016-04-01

Climate in the last Glacial was characterized by abrupt and large-scale changes around cold Heinrich-Events and warm Dansgaard-Oeschger excursions in the Northern high latitudes. The global repercussions of these periods of rapid dynamics are, to date, unconstrained. Here, we present a first statistical analysis of the global multi-proxy ACER (Abrupt Climate Changes and Environmental Responses) sea surface temperature dataset, spanning the last 80 thousand years, to investigate the spatial footprints of glacial climate dynamics. In a first step we evaluate the spatial and temporal variability throughout the Glacial period, and contrast them with that during the Holocene. In a second step we investigate to which extent a temporal synchroneity of extreme events during the Glacial is detectable in the proxy records, and analyze the reversibility of Glacial dynamics.

Evaluation of proxy-based millennial reconstruction methods

Energy Technology Data Exchange (ETDEWEB)

Lee, Terry C.K.; Tsao, Min [University of Victoria, Department of Mathematics and Statistics, Victoria, BC (Canada); Zwiers, Francis W. [Environment Canada, Climate Research Division, Toronto, ON (Canada)

2008-08-15

A range of existing statistical approaches for reconstructing historical temperature variations from proxy data are compared using both climate model data and real-world paleoclimate proxy data. We also propose a new method for reconstruction that is based on a state-space time series model and Kalman filter algorithm. The state-space modelling approach and the recently developed RegEM method generally perform better than their competitors when reconstructing interannual variations in Northern Hemispheric mean surface air temperature. On the other hand, a variety of methods are seen to perform well when reconstructing surface air temperature variability on decadal time scales. An advantage of the new method is that it can incorporate additional, non-temperature, information into the reconstruction, such as the estimated response to external forcing, thereby permitting a simultaneous reconstruction and detection analysis as well as future projection. An application of these extensions is also demonstrated in the paper. (orig.)

The Use of Proxy Caches for File Access in a Multi-Tier Grid Environment

International Nuclear Information System (INIS)

Brun, R; Duellmann, D; Ganis, G; Janyst, L; Peters, A J; Rademakers, F; Sindrilaru, E; Hanushevsky, A

2011-01-01

The use of proxy caches has been extensively studied in the HEP environment for efficient access of database data and showed significant performance with only very moderate operational effort at higher grid tiers (T2, T3). In this contribution we propose to apply the same concept to the area of file access and analyse the possible performance gains, operational impact on site services and applicability to different HEP use cases. Base on a proof-of-concept studies with a modified XROOT proxy server we review the cache efficiency and overheads for access patterns of typical ROOT based analysis programs. We conclude with a discussion of the potential role of this new component at the different tiers of a distributed computing grid.

New directions in hydro-climatic histories: observational data recovery, proxy records and the atmospheric circulation reconstructions over the earth (ACRE) initiative in Southeast Asia

Science.gov (United States)

Williamson, Fiona; Allan, Rob; Switzer, Adam D.; Chan, Johnny C. L.; Wasson, Robert James; D'Arrigo, Rosanne; Gartner, Richard

2015-12-01

The value of historic observational weather data for reconstructing long-term climate patterns and the detailed analysis of extreme weather events has long been recognized (Le Roy Ladurie, 1972; Lamb, 1977). In some regions however, observational data has not been kept regularly over time, or its preservation and archiving has not been considered a priority by governmental agencies. This has been a particular problem in Southeast Asia where there has been no systematic country-by-country method of keeping or preserving such data, the keeping of data only reaches back a few decades, or where instability has threatened the survival of historic records. As a result, past observational data are fragmentary, scattered, or even absent altogether. The further we go back in time, the more obvious the gaps. Observational data can be complimented however by historical documentary or proxy records of extreme events such as floods, droughts and other climatic anomalies. This review article highlights recent initiatives in sourcing, recovering, and preserving historical weather data and the potential for integrating the same with proxy (and other) records. In so doing, it focuses on regional initiatives for data research and recovery - particularly the work of the international Atmospheric Circulation Reconstructions over the Earth's (ACRE) Southeast Asian regional arm (ACRE SEA) - and the latter's role in bringing together disparate, but interrelated, projects working within this region. The overarching goal of the ACRE SEA initiative is to connect regional efforts and to build capacity within Southeast Asian institutions, agencies and National Meteorological and Hydrological Services (NMHS) to improve and extend historical instrumental, documentary and proxy databases of Southeast Asian hydroclimate, in order to contribute to the generation of high-quality, high-resolution historical hydroclimatic reconstructions (reanalyses) and, to build linkages with humanities researchers

Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments.

Science.gov (United States)

Maina, Joseph; de Moel, Hans; Vermaat, Jan E; Bruggemann, J Henrich; Guillaume, Mireille M M; Grove, Craig A; Madin, Joshua S; Mertz-Kraus, Regina; Zinke, Jens

2012-10-01

Understanding the linkages between coastal watersheds and adjacent coral reefs is expected to lead to better coral reef conservation strategies. Our study aims to examine the main predictors of environmental proxies recorded in near shore corals and therefore how linked near shore reefs are to the catchment physical processes. To achieve these, we developed models to simulate hydrology of two watersheds in Madagascar. We examined relationships between environmental proxies derived from massive Porites spp. coral cores (spectral luminescence and barium/calcium ratios), and corresponding time-series (1950-2006) data of hydrology, climate, land use and human population growth. Results suggest regional differences in the main environmental drivers of reef sedimentation: on annual time-scales, precipitation, river flow and sediment load explained the variability in coral proxies of river discharge for the northeast region, while El Niño-Southern Oscillation (ENSO) and temperature (air and sea surface) were the best predictors in the southwest region. Copyright © 2012 Elsevier Ltd. All rights reserved.

Export of microplastics from land to sea. A modelling approach

NARCIS (Netherlands)

Siegfried, Max; Koelmans, A.A.; Besseling, E.; Kroeze, C.

2017-01-01

Quantifying the transport of plastic debris from river to sea is crucial for assessing the risks of plastic debris to human health and the environment. We present a global modelling approach to analyse the composition and quantity of point-source microplastic fluxes from European rivers to the sea.

Extended multi-configuration quasi-degenerate perturbation theory: the new approach to multi-state multi-reference perturbation theory.

Science.gov (United States)

Granovsky, Alexander A

2011-06-07

The distinctive desirable features, both mathematically and physically meaningful, for all partially contracted multi-state multi-reference perturbation theories (MS-MR-PT) are explicitly formulated. The original approach to MS-MR-PT theory, called extended multi-configuration quasi-degenerate perturbation theory (XMCQDPT), having most, if not all, of the desirable properties is introduced. The new method is applied at the second order of perturbation theory (XMCQDPT2) to the 1(1)A(')-2(1)A(') conical intersection in allene molecule, the avoided crossing in LiF molecule, and the 1(1)A(1) to 2(1)A(1) electronic transition in cis-1,3-butadiene. The new theory has several advantages compared to those of well-established approaches, such as second order multi-configuration quasi-degenerate perturbation theory and multi-state-second order complete active space perturbation theory. The analysis of the prevalent approaches to the MS-MR-PT theory performed within the framework of the XMCQDPT theory unveils the origin of their common inherent problems. We describe the efficient implementation strategy that makes XMCQDPT2 an especially useful general-purpose tool in the high-level modeling of small to large molecular systems. © 2011 American Institute of Physics

Methodological Considerations in Couples' Fertility Intentions: Missing Men and the Viability of Women's Proxy Reports.

Science.gov (United States)

Stykes, J Bart

2018-02-19

Introduction Recent efforts show potential to advance research on unintended childbearing by taking a couple-level approach. However, this work has neither adequately addressed methodological concerns stemming from the challenges associated with male fertility data nor considered the viability of women's proxy reports of fathers intentions. Methods Data from the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) were used to assess the implications of low response rates among men on couples' unintended childbearing. Then, the accuracy of women's proxy reports of fathers intentions was assessed. Weighted logistic regression analyses were conducted to determine how women's characteristics were associated with men's survey participation whereas weighted multinomial logistic regression analyses were applied to determine how women's characteristics were linked with the accuracy of her proxy report. Results Almost half (46%) of women cannot be matched with data from the child's father, and this discrepancy is most problematic for women who are black, foreign-born, less educated, and unmarried at birth. Women's proxy reports appear viable as 75% of women's reports are consistent with men's responses. Yet, proxy reports underestimate disagreement in couples' intentions as mothers who intended the birth are at an increased risk of "inaccurately" reporting that fathers share their intentions. Discussion Direct approaches to couples' intentions yield privileged samples and systematically omit women at the greatest risk of an unintended birth. However, proxies underestimate disagreement in couples' intentions-a key contribution to the couple approach. Accordingly each approach has its own merits which must be considered in light of specified research questions.

CGLXTouch: A multi-user multi-touch approach for ultra-high-resolution collaborative workspaces

KAUST Repository

Ponto, Kevin

2011-06-01

This paper presents an approach for empowering collaborative workspaces through ultra-high resolution tiled display environments concurrently interfaced with multiple multi-touch devices. Multi-touch table devices are supported along with portable multi-touch tablet and phone devices, which can be added to and removed from the system on the fly. Events from these devices are tagged with a device identifier and are synchronized with the distributed display environment, enabling multi-user support. As many portable devices are not equipped to render content directly, a remotely scene is streamed in. The presented approach scales for large numbers of devices, providing access to a multitude of hands-on techniques for collaborative data analysis. © 2011 Elsevier B.V. All rights reserved.

Mechanistic controls on diverse fates of terrestrial organic components in the East China Sea

NARCIS (Netherlands)

Zhu, C.; Wagner, T.; Talbot, H.M.; Weijers, J.W.H.; Pan, J.-M.; Pancost, R.D.

2013-01-01

Terrestrial carbon transferred from the land to sea is a critical component of the global carbon cycle. A range of geochemical proxies has been developed to fingerprint the fate of terrestrial organic matter (TOM) in marine sediments. However, discrepancies among different proxies limit our ability

Analytical strategic environmental assessment (ANSEA) developing a new approach to SEA

International Nuclear Information System (INIS)

Dalkmann, Holger; Herrera, Rodrigo Jiliberto; Bongardt, Daniel

2004-01-01

The objective of analytical strategic environmental assessment (ANSEA) is to provide a decision-centred approach to the SEA process. The ANSEA project evolved from the realisation that, in many cases, SEA, as currently practised, is not able to ensure an appropriate integration of environmental values. The focus of SEA is on predicting impacts, but the tool takes no account of the decision-making processes it is trying to influence. At strategic decision-making levels, in turn, it is often difficult to predict impacts with the necessary exactitude. The decision-making sciences could teach some valuable lessons here. Instead of focusing on the quantitative prediction of environmental consequences, the ANSEA approach concentrates on the integration of environmental objectives into decision-making processes. Thus, the ANSEA approach provides a framework for analysing and assessing the decision-making processes of policies, plans and programmes (PPP). To enhance environmental integration into the decision-making process, decision windows (DW) can be identified. The approach is designed to be objective and transparent to ensure that environmental considerations are taken into account, or--from an ex-post perspective--to allow an evaluation of how far environmental considerations have been integrated into the decision-making process under assessment. The paper describes the concepts and the framework of the ANSEA approach and discusses its relation to SEA and the EC Directive

Participatory Design of Multi-Use Platforms at Sea

Directory of Open Access Journals (Sweden)

Sander van den Burg

2016-01-01

Full Text Available European oceans are subject to rapid development. New activities such as aquaculture and ocean energy have gained importance. This triggers interest in “multi-use platforms at sea” (MUPS, i.e., areas at sea in which different activities are combined. MUPS are complex features with regards to technology, governance, and financial, socioeconomic, and environmental aspects. To identify realistic and sustainable solutions and designs for MUPS, the MERMAID project applied a participatory design process (PDP involving a range of stakeholders representing companies, authorities, researchers, and NGOs. This paper evaluates if and how the participatory design process contributed to the design of multi-use platforms. It is based on interviews with the managers of the case study sites and a questionnaire administered to all stakeholders participating in the PDP workshops. Analyzing the four case studies, we conclude that the participatory design process has had a valuable contribution to the development of the four different designs of MUPS, even though the preconditions for carrying out a participatory design process differed between sites. In all four cases, the process has been beneficial in generating new and shared knowledge. It brought new design issues to the table and increased knowledge and understanding among the different stakeholders.

Comparison of clay mineral stratigraphy to other proxy palaeoclimate indicators in the Mesozoic of NW Europe.

Science.gov (United States)

Ruffell, Alastair; McKinley, Jennifer M; Worden, Richard H

2002-04-15

This paper reviews the opportunities and pitfalls associated with using clay mineralogical analysis in palaeoclimatic reconstructions. Following this, conjunctive methods of improving the reliability of clay mineralogical analysis are reviewed. The Mesozoic succession of NW Europe is employed as a case study. This demonstrates the relationship between clay mineralogy and palaeoclimate. Proxy analyses may be integrated with clay mineralogical analysis to provide an assessment of aridity-humidity contrasts in the hinterland climate. As an example, the abundance of kaolinite through the Mesozoic shows that, while interpretations may be difficult, the Mesozoic climate of NW Europe was subject to great changes in rates of continental precipitation. We may compare sedimentological (facies, mineralogy, geochemistry) indicators of palaeoprecipitation with palaeotemperature estimates. The integration of clay mineralogical analyses with other sedimentological proxy indicators of palaeoclimate allows differentiation of palaeoclimatic effects from those of sea-level and tectonic change. We may also observe how widespread palaeoclimate changes were; whether they were diachronous or synchronous; how climate, sea level and tectonics interact to control sedimentary facies and what palaeoclimate indicators are reliable.

Reconstructing sea level from paleo and projected temperatures 200 to 2100 AD

DEFF Research Database (Denmark)

Grinsted, Aslak; Moore, John; Jevrejeva, Svetlana

2010-01-01

-proxy reconstructions assuming that the established relationship between temperature and sea level holds from 200 to 2100 ad. Over the last 2,000 years minimum sea level (-19 to -26 cm) occurred around 1730 ad, maximum sea level (12–21 cm) around 1150 AD. Sea level 2090–2099 is projected to be 0.9 to 1.3 m for the A1B...

Atrotorquata lineata as a proxy for Juncus roemerianus, Part II: Tracking changes in positions of Juncus roemerianus marshes through time by use of the fungal proxy Atrotorquata lineata

Directory of Open Access Journals (Sweden)

Marsh Pamela E.

2016-12-01

Full Text Available Juncus roemerianus is a species that occurs at the upper reaches of salt water influence in marshes from Delaware to Texas. As such, J. roemerianus is a good marker for sea level, defined for this study as mean highest high water; thus, being able to track its positions over time should enable one to track past changes in relative sea level. In 2006, a palynomorphic fingerprint to identify surface sediment from J. roemerianus marshes was discovered in a South Carolina study (Marsh 2006, Marsh & Cohen 2008. Further study (Marsh & Cohen 2016 showed that one component of this fingerprint, the spore of the fungus Atrotorquata lineata, was so omnipresent in surface sediment from J. roemerianus marshes that the fungus, by itself, can be considered a proxy for J. roemerianus marshes.

12 CFR 569.4 - Proxy soliciting material.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Proxy soliciting material. 569.4 Section 569.4 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PROXIES § 569.4 Proxy soliciting material. No solicitation of a proxy shall be made by means of any statement, form of proxy...

12 CFR 569.2 - Form of proxies.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Form of proxies. 569.2 Section 569.2 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PROXIES § 569.2 Form of proxies. Every form of proxy shall conform to the following requirements: (a) The proxy shall be revocable at will by...

A 350 Year Cloud Cover Reconstruction Deduced from Caribbean Coral Proxies

Science.gov (United States)

Winter, Amos; Sammarco, Paul; Mikolajewicz, Uwe; Jury, Mark; Zanchettin, Davide

2015-04-01

Clouds are a major factor contributing to climate change with respect to a variety of effects on the earth's climates, primarily radiative effects, amelioration of heating, and regional changes in precipitation patterns. There have been very few studies of decadal and longer term changes in cloud cover in the tropics and sub-tropics, both over land and the ocean. In the tropics, there is great uncertainty regarding how global warming will affect cloud cover. Observational satellite data is so short that it is difficult to discern any temporal trends. The skeletons of scleractinian corals are considered to contain among the best records of high-resolution (sub-annual) environmental variability in the tropical and sub-tropical oceans. Corals generally live in well-mixed coastal regions and can often record environmental conditions of large areas of the upper ocean. This is particularly the case at low latitudes. Scleractinian corals are sessile, epibenthic fauna, and the type of environmental information recorded at the location where the coral has been living is dependent upon the species of coral considered and proxy index of interest. Zooxanthellate hermatypic corals in tropical and sub-tropical seas precipitate CaCO3 skeletons as they grow. This growth is made possible through the manufacture of CaCO3 crystals, facilitated by the zooxanthellae. During the process of crystallization, the holobiont binds carbon of different isotopes into the crystals. Stable carbon isotope concentrations vary with a variety of environmental conditions. In the Caribbean, δ13C in corals of the species Montastraea faveolata can be used as a proxy for changes in cloud cover. In this contribution, we will demonstrate that the stable isotope 13C varies concomitantly with cloud cover and present a new reconstruction of cloud cover over the Caribbean Sea that extends back to the year 1760. We will show that there is good agreement between the main features of our coral proxy record of

PMHT Approach for Multi-Target Multi-Sensor Sonar Tracking in Clutter.

Science.gov (United States)

Li, Xiaohua; Li, Yaan; Yu, Jing; Chen, Xiao; Dai, Miao

2015-11-06

Multi-sensor sonar tracking has many advantages, such as the potential to reduce the overall measurement uncertainty and the possibility to hide the receiver. However, the use of multi-target multi-sensor sonar tracking is challenging because of the complexity of the underwater environment, especially the low target detection probability and extremely large number of false alarms caused by reverberation. In this work, to solve the problem of multi-target multi-sensor sonar tracking in the presence of clutter, a novel probabilistic multi-hypothesis tracker (PMHT) approach based on the extended Kalman filter (EKF) and unscented Kalman filter (UKF) is proposed. The PMHT can efficiently handle the unknown measurements-to-targets and measurements-to-transmitters data association ambiguity. The EKF and UKF are used to deal with the high degree of nonlinearity in the measurement model. The simulation results show that the proposed algorithm can improve the target tracking performance in a cluttered environment greatly, and its computational load is low.

Airborne LiDAR for the Detection of Archaeological Vegetation Marks Using Biomass as a Proxy

Directory of Open Access Journals (Sweden)

David Stott

2015-02-01

Full Text Available In arable landscapes, the airborne detection of archaeological features is often reliant on using the properties of the vegetation cover as a proxy for sub-surface features in the soil. Under the right conditions, the formation of vegetation marks allows archaeologists to identify and interpret archaeological features. Using airborne Laser Scanning, based on the principles of Light Detection and Ranging (LiDAR to detect these marks is challenging, particularly given the difficulties of resolving subtle changes in a low and homogeneous crop with these sensors. In this paper, an experimental approach is adopted to explore how these marks could be detected as variations in canopy biomass using both range and full waveform LiDAR data. Although some detection was achieved using metrics of the full waveform data, it is the novel multi-temporal method of using discrete return data to detect and characterise archaeological vegetation marks that is offered for further consideration. This method was demonstrated to be applicable over a range of capture conditions, including soils deemed as difficult (i.e., clays and other heavy soils, and should increase the certainty of detection when employed in the increasingly multi-sensor approaches to heritage prospection and management.

Mobile Multicast in Hierarchical Proxy Mobile IPV6

Science.gov (United States)

Hafizah Mohd Aman, Azana; Hashim, Aisha Hassan A.; Mustafa, Amin; Abdullah, Khaizuran

2013-12-01

Mobile Internet Protocol Version 6 (MIPv6) environments have been developing very rapidly. Many challenges arise with the fast progress of MIPv6 technologies and its environment. Therefore the importance of improving the existing architecture and operations increases. One of the many challenges which need to be addressed is the need for performance improvement to support mobile multicast. Numerous approaches have been proposed to improve mobile multicast performance. This includes Context Transfer Protocol (CXTP), Hierarchical Mobile IPv6 (HMIPv6), Fast Mobile IPv6 (FMIPv6) and Proxy Mobile IPv6 (PMIPv6). This document describes multicast context transfer in hierarchical proxy mobile IPv6 (H-PMIPv6) to provide better multicasting performance in PMIPv6 domain.

Land-sea coupling of early Pleistocene glacial cycles in the southern North Sea exhibit dominant Northern Hemisphere forcing

Science.gov (United States)

Donders, Timme H.; van Helmond, Niels A. G. M.; Verreussel, Roel; Munsterman, Dirk; ten Veen, Johan; Speijer, Robert P.; Weijers, Johan W. H.; Sangiorgi, Francesca; Peterse, Francien; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.; Lourens, Lucas; Kuhlmann, Gesa; Brinkhuis, Henk

2018-03-01

We assess the disputed phase relations between forcing and climatic response in the early Pleistocene with a spliced Gelasian (˜ 2.6-1.8 Ma) multi-proxy record from the southern North Sea basin. The cored sections couple climate evolution on both land and sea during the intensification of Northern Hemisphere glaciation (NHG) in NW Europe, providing the first well-constrained stratigraphic sequence of the classic terrestrial Praetiglian stage. Terrestrial signals were derived from the Eridanos paleoriver, a major fluvial system that contributed a large amount of freshwater to the northeast Atlantic. Due to its latitudinal position, the Eridanos catchment was likely affected by early Pleistocene NHG, leading to intermittent shutdown and reactivation of river flow and sediment transport. Here we apply organic geochemistry, palynology, carbonate isotope geochemistry, and seismostratigraphy to document both vegetation changes in the Eridanos catchment and regional surface water conditions and relate them to early Pleistocene glacial-interglacial cycles and relative sea level changes. Paleomagnetic and palynological data provide a solid integrated timeframe that ties the obliquity cycles, expressed in the borehole geophysical logs, to Marine Isotope Stages (MIS) 103 to 92, independently confirmed by a local benthic oxygen isotope record. Marine and terrestrial palynological and organic geochemical records provide high-resolution reconstructions of relative terrestrial and sea surface temperature (TT and SST), vegetation, relative sea level, and coastal influence.During the prominent cold stages MIS 98 and 96, as well as 94, the record indicates increased non-arboreal vegetation, low SST and TT, and low relative sea level. During the warm stages MIS 99, 97, and 95 we infer increased stratification of the water column together with a higher percentage of arboreal vegetation, high SST, and relative sea level maxima. The early Pleistocene distinct warm-cold alterations are

Climate oscillations reflected within the microbiome of Arabian Sea sediments

KAUST Repository

Orsi, William D.; Coolen, Marco J. L.; Wuchter, Cornelia; He, Lijun; More, Kuldeep D.; Irigoien, Xabier; Chust, Guillem; Johnson, Carl; Hemingway, Jordon D.; Lee, Mitchell; Galy, Valier; Giosan, Liviu

2017-01-01

Selection of microorganisms in marine sediment is shaped by energy-yielding electron acceptors for respiration that are depleted in vertical succession. However, some taxa have been reported to reflect past depositional conditions suggesting they have experienced weak selection after burial. In sediments underlying the Arabian Sea oxygen minimum zone (OMZ), we performed the first metagenomic profiling of sedimentary DNA at centennial-scale resolution in the context of a multi-proxy paleoclimate reconstruction. While vertical distributions of sulfate reducing bacteria and methanogens indicate energy-based selection typical of anoxic marine sediments, 5–15% of taxa per sample exhibit depth-independent stratigraphies indicative of paleoenvironmental selection over relatively short geological timescales. Despite being vertically separated, indicator taxa deposited under OMZ conditions were more similar to one another than those deposited in bioturbated intervals under intervening higher oxygen. The genomic potential for denitrification also correlated with palaeo-OMZ proxies, independent of sediment depth and available nitrate and nitrite. However, metagenomes revealed mixed acid and Entner-Dourdoroff fermentation pathways encoded by many of the same denitrifier groups. Fermentation thus may explain the subsistence of these facultatively anaerobic microbes whose stratigraphy follows changing paleoceanographic conditions. At least for certain taxa, our analysis provides evidence of their paleoenvironmental selection over the last glacial-interglacial cycle.

Climate oscillations reflected within the microbiome of Arabian Sea sediments

KAUST Repository

Orsi, William D.

2017-07-14

Selection of microorganisms in marine sediment is shaped by energy-yielding electron acceptors for respiration that are depleted in vertical succession. However, some taxa have been reported to reflect past depositional conditions suggesting they have experienced weak selection after burial. In sediments underlying the Arabian Sea oxygen minimum zone (OMZ), we performed the first metagenomic profiling of sedimentary DNA at centennial-scale resolution in the context of a multi-proxy paleoclimate reconstruction. While vertical distributions of sulfate reducing bacteria and methanogens indicate energy-based selection typical of anoxic marine sediments, 5–15% of taxa per sample exhibit depth-independent stratigraphies indicative of paleoenvironmental selection over relatively short geological timescales. Despite being vertically separated, indicator taxa deposited under OMZ conditions were more similar to one another than those deposited in bioturbated intervals under intervening higher oxygen. The genomic potential for denitrification also correlated with palaeo-OMZ proxies, independent of sediment depth and available nitrate and nitrite. However, metagenomes revealed mixed acid and Entner-Dourdoroff fermentation pathways encoded by many of the same denitrifier groups. Fermentation thus may explain the subsistence of these facultatively anaerobic microbes whose stratigraphy follows changing paleoceanographic conditions. At least for certain taxa, our analysis provides evidence of their paleoenvironmental selection over the last glacial-interglacial cycle.

A 13000-year, high-resolution multi-proxy record of climate variability with episodes of enhanced atmospheric dust in Western Asia: Evidence from Neor peat complex in NW Iran

Science.gov (United States)

Sharifi, O.; Pourmand, A.; Canuel, E. A.; Peterson, L. C.

2011-12-01

The regional climate over West Asia, extending between Iran and the Arabian Peninsula to the eastern Mediterranean Sea, is governed by interactions between three major synoptic systems; mid-latitude Westerlies, the Siberian Anticyclone and the Indian Ocean Summer Monsoon. In recent years, a number of paleoclimate studies have drawn potential links between episodes of abrupt climate change during the Holocene, and the rise and fall of human civilizations across the "Fertile Crescent" of West Asia. High-resolution archives of climate variability from this region, however, are scarce, and at times contradicting. For example, while pollen and planktonic data from lakes in Turkey and Iran suggest that dry, continental conditions prevailed during the early-middle Holocene, oxygen isotope records indicate that relatively wet conditions dominated during this interval over West Asia. We present interannual to decadal multi-proxy records of climate variability from a peat complex in NW Iran to reconstruct changes in moisture and atmospheric dust content during the last 13000 years. Radiocarbon dating on 20 samples from a 775-cm peat core show a nearly constant rate of accumulation (1.7 mm yr-1, R2=0.99) since 13356 ± 116 cal yr B.P. Down-core X-ray fluorescence measurements of conservative lithogenic elements (e.g., Al, Zr, Ti) as well as redox-sensitive elements (e.g., Fe, K, Rb, Zn, Cu, and Co) at 2 mm intervals reveal several periods of elevated dust input to this region since the early Holocene. Down-core variations of total organic carbon and total nitrogen co-vary closely and are inversely correlated with conservative lithogenic elements (Al, Si, Ti), indicating a potential link between climate change and accumulation of organic carbon in the Neor peat mire. Major episodes of enhanced dust deposition (13000-12000, 11700-11200, 9200-8800, 7000-6000, 4200-3200, 2800-2200 and 1500-600 cal yr B.P) are in good agreement with other proxy records that document more arid

The MSY concept in a multi-objective fisheries environment – lessons learned from the North Sea

DEFF Research Database (Denmark)

Kempf, Alexander; Mumford, John; Levontin, Polina

2016-01-01

One of the most important goals in current fisheries management is to maintain or restore stocks above levels that can produce the maximum sustainable yield (MSY). However, it may not be feasible to achieve MSY simultaneously for multiple species because of trade-offs that result from interactions...... with stakeholders as well as scenario modelling with bio-economic and multi-species models. It is difficult to intuitively anticipate the consequences of complex trade-offs and it is also complicated to address them from a political point of view. However, scenario modelling showed that the current approach...... of treating each stock separately and ignoring trade-offs may result in unacceptable ecosystem, economic or social effects in North Sea fisheries. Setting FMSY as a management target without any flexibility for compromises may lead to disappointment for some of the stakeholders. To treat FMSY no longer...

Sea level reconstruction from satellite altimetry and tide gauge data

DEFF Research Database (Denmark)

Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

2012-01-01

Ocean satellite altimetry has provided global sets of sea level data for the last two decades, allowing determination of spatial patterns in global sea level. For reconstructions going back further than this period, tide gauge data can be used as a proxy. We examine different methods of combining...... for better sensitivity analysis with respect to spatial distribution, and tide gauge data are available around the Arctic Ocean, which may be important for a later high-latitude reconstruction....... satellite altimetry and tide gauge data using optimal weighting of tide gauge data, linear regression and EOFs, including automatic quality checks of the tide gauge time series. We attempt to augment the model using various proxies such as climate indices like the NAO and PDO, and investigate alternative...

Shareholder Activism through the Proxy Process

NARCIS (Netherlands)

Renneboog, L.D.R.; Szilagyi, P.G.

2009-01-01

This paper provides evidence on the corporate governance role of shareholderinitiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

Shareholder Activism Through the Proxy Process

NARCIS (Netherlands)

Renneboog, L.D.R.; Szilagyi, P.G.

2009-01-01

This paper provides evidence on the corporate governance role of shareholder-initiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

Investigating Arctic Sea Ice Survivability in the Beaufort Sea

Directory of Open Access Journals (Sweden)

Matthew Tooth

2018-02-01

Full Text Available Arctic sea ice extent has continued to decline in recent years, and the fractional coverage of multi-year sea ice has decreased significantly during this period. The Beaufort Sea region has been the site of much of the loss of multi-year sea ice, and it continues to play a large role in the extinction of ice during the melt season. We present an analysis of the influence of satellite-derived ice surface temperature, ice thickness, albedo, and downwelling longwave/shortwave radiation as well as latitude and airborne snow depth estimates on the change in sea ice concentration in the Beaufort Sea from 2009 to 2016 using a Lagrangian tracking database. Results from this analysis indicate that parcels that melt during summer in the Beaufort Sea reside at lower latitudes and have lower ice thickness at the beginning of the melt season in most cases. The influence of sea ice thickness and snow depth observed by IceBridge offers less conclusive results, with some years exhibiting higher thicknesses/depths for melted parcels. Parcels that melted along IceBridge tracks do exhibit lower latitudes and ice thicknesses, however, which indicates that earlier melt and breakup of ice may contribute to a greater likelihood of extinction of parcels in the summer.

Reprocessing of multi-channel seismic-reflection data collected in the Chukchi Sea

Science.gov (United States)

Agena, W.F.; Lee, M.W.; Hart, P.E.

2001-01-01

Contained on this set of two CD-ROMs are stacked and migrated multi-channel seismic-reflection data for 44 lines recorded in the Chukchi Sea, northern Alaska, by the United States Geological Survey in 1977, 1978, and 1980. All data were reprocessed by the USGS in 2000 using updated methods. The resulting final data have both increased temporal and spatial resolution thus providing improved interpretability. An added benefit of these CD-ROMs is that they are a more stable, long-term archival medium for the data.

A comparison of PMIP2 model simulations and the MARGO proxy reconstruction for tropical sea surface temperatures at last glacial maximum

Energy Technology Data Exchange (ETDEWEB)

Otto-Bliesner, Bette L.; Brady, E.C. [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States); Schneider, Ralph; Weinelt, M. [Christian-Albrechts Universitaet, Institut fuer Geowissenschaften, Kiel (Germany); Kucera, M. [Eberhard-Karls Universitaet Tuebingen, Institut fuer Geowissenschaften, Tuebingen (Germany); Abe-Ouchi, A. [The University of Tokyo, Center for Climate System Research, Kashiwa (Japan); Bard, E. [CEREGE, College de France, CNRS, Universite Aix-Marseille, Aix-en-Provence (France); Braconnot, P.; Kageyama, M.; Marti, O.; Waelbroeck, C. [Unite mixte CEA-CNRS-UVSQ, Laboratoire des Sciences du Climat et de l' Environnement, Gif-sur-Yvette Cedex (France); Crucifix, M. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Hewitt, C.D. [Met Office Hadley Centre, Exeter (United Kingdom); Paul, A. [Bremen University, Department of Geosciences, Bremen (Germany); Rosell-Mele, A. [Universitat Autonoma de Barcelona, ICREA and Institut de Ciencia i Tecnologia Ambientals, Barcelona (Spain); Weber, S.L. [Royal Netherlands Meteorological Institute (KNMI), De Bilt (Netherlands); Yu, Y. [Chinese Academy of Sciences, LASG, Institute of Atmospheric Physics, Beijing (China)

2009-05-15

Results from multiple model simulations are used to understand the tropical sea surface temperature (SST) response to the reduced greenhouse gas concentrations and large continental ice sheets of the last glacial maximum (LGM). We present LGM simulations from the Paleoclimate Modelling Intercomparison Project, Phase 2 (PMIP2) and compare these simulations to proxy data collated and harmonized within the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface Project (MARGO). Five atmosphere-ocean coupled climate models (AOGCMs) and one coupled model of intermediate complexity have PMIP2 ocean results available for LGM. The models give a range of tropical (defined for this paper as 15 S-15 N) SST cooling of 1.0-2.4 C, comparable to the MARGO estimate of annual cooling of 1.7{+-}1 C. The models simulate greater SST cooling in the tropical Atlantic than tropical Pacific, but interbasin and intrabasin variations of cooling are much smaller than those found in the MARGO reconstruction. The simulated tropical coolings are relatively insensitive to season, a feature also present in the MARGO transferred-based estimates calculated from planktonic foraminiferal assemblages for the Indian and Pacific Oceans. These assemblages indicate seasonality in cooling in the Atlantic basin, with greater cooling in northern summer than northern winter, not captured by the model simulations. Biases in the simulations of the tropical upwelling and thermocline found in the preindustrial control simulations remain for the LGM simulations and are partly responsible for the more homogeneous spatial and temporal LGM tropical cooling simulated by the models. The PMIP2 LGM simulations give estimates for the climate sensitivity parameter of 0.67 -0.83 C per Wm{sup -2}, which translates to equilibrium climate sensitivity for doubling of atmospheric CO{sub 2} of 2.6-3.1 C. (orig.)

towards a theory-based multi-dimensional framework for assessment in mathematics: The "SEA" framework

Science.gov (United States)

Anku, Sitsofe E.

1997-09-01

Using the reform documents of the National Council of Teachers of Mathematics (NCTM) (NCTM, 1989, 1991, 1995), a theory-based multi-dimensional assessment framework (the "SEA" framework) which should help expand the scope of assessment in mathematics is proposed. This framework uses a context based on mathematical reasoning and has components that comprise mathematical concepts, mathematical procedures, mathematical communication, mathematical problem solving, and mathematical disposition.

Monsoon Variability In The Western Arabian Sea During Last 10,000 Years BP: A Planktic Foraminiferal Abundances And It's Stable Isotope Records

Science.gov (United States)

Singh, A. K.; Tiwari, M.; Sinha, D. K.; Ramesh, R.

2007-12-01

: The western Arabian Sea responds to the southwest monsoon winds by upwelling colder and nutrient rich waters from the deeper layers, causing a reduction in the sea surface temperature and enhanced biological productivity. A number of paleoclimatic studies have been carried out in this region to elucidate past monsoon variability (Sirocco et al., 1993; Gupta et al, 2003; Tiwari, 2005; Saher et.al.; 2007). Globigerina bulloides, a planktic foraminiferal species normally inhabiting surface ocean waters in temperate latitudes ( Be and Tolderlund , 1977) also becomes abundant at tropical latitudes upwelling occurs, and in these cases its abundance can exceed considerably. The conspicuous fluctuation in the abundance of Gg.bulloides during upwelling and non upwelling intervals is established through several studies ( Thiede and Junger, 1980, Gupta et al, 2003) This robust relation has been used as a proxy for wind velocity at several different times in the past in the Arabian Sea (Anderson et.al., 2002). A significant result from some of these centennially resolved Holocene records is declining abundance of Globigerina bulloides which is paralleled by reduced insolation record and this has been inferred as declining strength of Asian Monsoon. We are presenting here the data from the core SS4018 from near the Gulf of Aden, Western Arabian Sea taken at a water depth of 2830 m, precisely dated by the radiocarbon method using Accelerator Mass Spectrometry on planktonic foraminiferal separates. We have carried out the planktic foraminiferal census counts for each sample to know the relative abundance of key species. In addition to this, we have also employed multi- proxy approach such as oxygen and carbon isotopes of planktic foraminiferal tests, TOC, CaCO3 (%) to strengthen our interpretation and also to understand the relationships amongst the proxies themselves. Abundance of the key planktic foraminiferal species and other proxy records reveal at least 3 major climatic

Multidecadal variations in the early Holocene outflow of Red Sea Water into the Arabian Sea

NARCIS (Netherlands)

Jung, S.J.A.; Ganssen, G.M.; Davies, G.R.

2001-01-01

We present Holocene stable oxygen isotope data from the deep Arabian Sea off Somalia at a decadal time resolution as a proxy for the history of intermediate/upper deep water. These data show an overall δ18O reduction by 0.5‰ between 10 and ~6.5 kyr B.P. superimposed upon short-term δ18O variations

Microstructural growth increments in the brachiopods Liothyrella uva and L. neozelanica: preliminary study of growth analysis and proxy calibration

Science.gov (United States)

Romanin, Marco; Aleksandra Bitner, Maria; Brand, Uwe

2017-04-01

Brachiopods secrete low-Mg calcite shells in near equilibrium with the surrounding sea water, with respect to their secondary and tertiary layers. For this reason, in recent years they have been intensively studied as archives for oceanographic and environmental proxies. The primary layer has been shown not to be deposited in equilibrium with the ambient sea water, leading to a novel cleaning protocol proposed by Zaki et al (2015). In the spite of improving on existing proxies, the shell microstructure and growth has to be taken in to account in their applications. The secretion of the primary layer is known to be external of the shell, but in SEM investigations of Liothyrella uva and L. neozelanica we discovered that the primary layer has its origin within the fibres of the secondary layer. Furthermore, the primary layer calcite is not a continuum but instead it consists of a 'new' band for each major growth increment. There is overlap between the preceding and subsequent 'band' (or shingles) of the primary layer, which may extend into the secondary/tertiary layer. This finding may lead to more comprehensive knowledge of shell microstructure processes in L. uva and L. neozelanica that may be applied and extended to other modern and fossil brachiopods, including age dating of brachiopods. This discovery may make brachiopod archives more reliable and consistent proxies when applied to and interpreting their geological record.

Bayesian Statistical Analysis of Historical and Late Holocene Rates of Sea-Level Change

Science.gov (United States)

Cahill, Niamh; Parnell, Andrew; Kemp, Andrew; Horton, Benjamin

2014-05-01

A fundamental concern associated with climate change is the rate at which sea levels are rising. Studies of past sea level (particularly beyond the instrumental data range) allow modern sea-level rise to be placed in a more complete context. Considering this, we perform a Bayesian statistical analysis on historical and late Holocene rates of sea-level change. The data that form the input to the statistical model are tide-gauge measurements and proxy reconstructions from cores of coastal sediment. The aims are to estimate rates of sea-level rise, to determine when modern rates of sea-level rise began and to observe how these rates have been changing over time. Many of the current methods for doing this use simple linear regression to estimate rates. This is often inappropriate as it is too rigid and it can ignore uncertainties that arise as part of the data collection exercise. This can lead to over confidence in the sea-level trends being characterized. The proposed Bayesian model places a Gaussian process prior on the rate process (i.e. the process that determines how rates of sea-level are changing over time). The likelihood of the observed data is the integral of this process. When dealing with proxy reconstructions, this is set in an errors-in-variables framework so as to take account of age uncertainty. It is also necessary, in this case, for the model to account for glacio-isostatic adjustment, which introduces a covariance between individual age and sea-level observations. This method provides a flexible fit and it allows for the direct estimation of the rate process with full consideration of all sources of uncertainty. Analysis of tide-gauge datasets and proxy reconstructions in this way means that changing rates of sea level can be estimated more comprehensively and accurately than previously possible. The model captures the continuous and dynamic evolution of sea-level change and results show that not only are modern sea levels rising but that the rates

High-Resolution Mg/Ca Ratios in a Coralline Red Alga as a Proxy for Bering Sea Temperature Variations and Teleconnections

Science.gov (United States)

Halfar, J.; Steffen, H.; Kronz, A.; Steneck, R. S.; Adey, W.; Lebednik, P. A.

2009-05-01

We present the first continuous high-resolution record of Mg/Ca variations within an encrusting coralline red alga of the species Clathromorphum nereostratum from Amchitka Island, Aleutian Islands. Mg/Ca ratios of individual growth increments were analyzed by measuring a single point electron microprobe transect yielding a resolution of 15 samples/year on average, generating a continuous record from 1830 to 1967 of algal Mg/Ca variations. Results show that Mg/Ca ratios in the high-Mg calcite skeleton display pronounced annual cyclicity and archive late spring to late fall sea surface temperature (SST) corresponding to the main season of algal growth. Mg/Ca values correlate well to local SST (ERSSTJun-Nov, 1902-1967; r = 0.73 for 5-year mean), as well as to an air temperature record from the same region. Our data correlate well to a shorter Mg/Ca record from a second site, corroborating the ability of the alga to reliably record regional environmental signals. In addition, Mg/Ca ratios relate well to a 29-year stable oxygen isotope time series measured on the same sample, which provides additional support for the use of Mg as a paleotemperature proxy in coralline red algae, that is, unlike stable oxygen isotopes, not influenced by salinity fluctuations. High spatial correlation to large-scale SST variability in the North Pacific is observed, with patterns of strongest correlation following the direction of major oceanographic features (i.e., the signature of the Alaska Current and the Alaskan Stream), which play a key role in the exchange of water masses between the North Pacific and the Bering Sea through Aleutian Island passages. The time series further displays significant teleconnections with the signature of the Pacific Decadal Oscillation in the northeast Pacific and the Atlantic Multidecadal Oscillation.

12 CFR 569.3 - Holders of proxies.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Holders of proxies. 569.3 Section 569.3 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PROXIES § 569.3 Holders of proxies. No proxy of a mutual savings association with a term greater than eleven months or solicited at...

Tuneable resolution as a systems biology approach for multi-scale, multi-compartment computational models.

Science.gov (United States)

Kirschner, Denise E; Hunt, C Anthony; Marino, Simeone; Fallahi-Sichani, Mohammad; Linderman, Jennifer J

2014-01-01

The use of multi-scale mathematical and computational models to study complex biological processes is becoming increasingly productive. Multi-scale models span a range of spatial and/or temporal scales and can encompass multi-compartment (e.g., multi-organ) models. Modeling advances are enabling virtual experiments to explore and answer questions that are problematic to address in the wet-lab. Wet-lab experimental technologies now allow scientists to observe, measure, record, and analyze experiments focusing on different system aspects at a variety of biological scales. We need the technical ability to mirror that same flexibility in virtual experiments using multi-scale models. Here we present a new approach, tuneable resolution, which can begin providing that flexibility. Tuneable resolution involves fine- or coarse-graining existing multi-scale models at the user's discretion, allowing adjustment of the level of resolution specific to a question, an experiment, or a scale of interest. Tuneable resolution expands options for revising and validating mechanistic multi-scale models, can extend the longevity of multi-scale models, and may increase computational efficiency. The tuneable resolution approach can be applied to many model types, including differential equation, agent-based, and hybrid models. We demonstrate our tuneable resolution ideas with examples relevant to infectious disease modeling, illustrating key principles at work. © 2014 The Authors. WIREs Systems Biology and Medicine published by Wiley Periodicals, Inc.

Multi-proxy reconstructions of precipitation field in China over the past 500 years.

OpenAIRE

Shi, Feng; Zhao, sen; Guo, Zhengtang; Goosse, Hugues; Yin, Qiuzhen

2017-01-01

The dominant modes of variability of precipitation for the whole of China over the past millennium and the mechanism governing their spatial structure remain unclear. This is mainly due to insufficient high-resolution proxy records of precipitation in western China. Numerous tree-ring chronologies have recently been archived in publicly available databases through PAGES2k activities, and these provide an opportunity to refine precipitation field reconstructions for China. Ba...

POTENTIAL FOR DEVELOPMENT OF INTEGRATED MULTI-TROPHIC AQUACULTURE (IMTA IN THE ADRIATIC SEA

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Danijel Kanski

2012-12-01

Full Text Available Over recent years, scientific interest for investigating ecological, economical and social effects of Integrated Multi-trophic Aquaculture (IMTA has increased worldwide. Its development in the Mediterranean, including the Adriatic Sea, is still in the early stages. The main obstacle preventing IMTA to be commercially adopted is the lack of scientific information on choosing compatible species, knowing the carrying capacity of a production area and interactions between species feeding at different trophic levels, as well as its socio–economic impacts. Current experience in the area is based on smaller experimental studies of local importance but they generally give a good insight into potential of IMTA and its interactions with the environment. The aim of this paper was to overview current literature and experiences worldwide and to review the potential for adopting IMTA principles in the Adriatic Sea.

A New Approach to Sea Transportation: An Application in Turkey

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Alper Erturk

2017-04-01

Full Text Available This study has been conducted to detect the strengths and the improvement requiring areas of sea transportation in Turkey via SWOT analysis, and the opportunities this sector brings to Turkey and the threats that might appear have been put forward in several aspects. When the necessary advances have been made considering the outcomes of this study, it can be foreseen that Turkish navigation can make a swift progress and assume its place in the top 5 mercantile fleets of the World Trade Fleet. Moreover, this new approach that can be developed through the example of Turkey, especially in the context of SWOT analysis methodology, can get to be seen as a role model before the other developing countries.Sea transportation is not merely a transportation sector. Along with goods and human transportation, ship building industry, port services, sea insurance and sea tourism are among the many naval activities. Because of all these, sea transportation has a significant place in international trade. The overall commercial value of world trade mounting up to 15 trillion US dollars, 9 trillion dollars of this has been conducted via sea transportation. In other words, 60 percent of world commerce has been done through sea transportation (GISBIR, 2013. Furthermore, the volume of the dry bulk market via sea transportation is expected to grow by 6 percent between the years 2014 and 2018 (GISBIR, 2013.

Comparing children's GPS tracks with geospatial proxies for exposure to junk food.

Science.gov (United States)

Sadler, Richard C; Gilliland, Jason A

2015-01-01

Various geospatial techniques have been employed to estimate children's exposure to environmental cardiometabolic risk factors, including junk food. But many studies uncritically rely on exposure proxies which differ greatly from actual exposure. Misrepresentation of exposure by researchers could lead to poor decisions and ineffective policymaking. This study conducts a GIS-based analysis of GPS tracks--'activity spaces'--and 21 proxies for activity spaces (e.g. buffers, container approaches) for a sample of 526 children (ages 9-14) in London, Ontario, Canada. These measures are combined with a validated food environment database (including fast food and convenience stores) to create a series of junk food exposure estimates and quantify the errors resulting from use of different proxy methods. Results indicate that exposure proxies consistently underestimate exposure to junk foods by as much as 68%. This underestimation is important to policy development because children are exposed to more junk food than estimated using typical methods. Copyright © 2015 Elsevier Ltd. All rights reserved.

Technical Note: Probabilistically constraining proxy age–depth models within a Bayesian hierarchical reconstruction model

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J. P. Werner

2015-03-01

Full Text Available Reconstructions of the late-Holocene climate rely heavily upon proxies that are assumed to be accurately dated by layer counting, such as measurements of tree rings, ice cores, and varved lake sediments. Considerable advances could be achieved if time-uncertain proxies were able to be included within these multiproxy reconstructions, and if time uncertainties were recognized and correctly modeled for proxies commonly treated as free of age model errors. Current approaches for accounting for time uncertainty are generally limited to repeating the reconstruction using each one of an ensemble of age models, thereby inflating the final estimated uncertainty – in effect, each possible age model is given equal weighting. Uncertainties can be reduced by exploiting the inferred space–time covariance structure of the climate to re-weight the possible age models. Here, we demonstrate how Bayesian hierarchical climate reconstruction models can be augmented to account for time-uncertain proxies. Critically, although a priori all age models are given equal probability of being correct, the probabilities associated with the age models are formally updated within the Bayesian framework, thereby reducing uncertainties. Numerical experiments show that updating the age model probabilities decreases uncertainty in the resulting reconstructions, as compared with the current de facto standard of sampling over all age models, provided there is sufficient information from other data sources in the spatial region of the time-uncertain proxy. This approach can readily be generalized to non-layer-counted proxies, such as those derived from marine sediments.

ePRISM: A case study in multiple proxy and mixed temporal resolution integration

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Robinson, Marci M.; Dowsett, Harry J.

2010-01-01

As part of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project, we present the ePRISM experiment designed I) to provide climate modelers with a reconstruction of an early Pliocene warm period that was warmer than the PRISM interval (similar to 3.3 to 3.0 Ma), yet still similar in many ways to modern conditions and 2) to provide an example of how best to integrate multiple-proxy sea surface temperature (SST) data from time series with varying degrees of temporal resolution and age control as we begin to build the next generation of PRISM, the PRISM4 reconstruction, spanning a constricted time interval. While it is possible to tie individual SST estimates to a single light (warm) oxygen isotope event, we find that the warm peak average of SST estimates over a narrowed time interval is preferential for paleoclimate reconstruction as it allows for the inclusion of more records of multiple paleotemperature proxies.

A multi-stage oil-water-separating process design for the sea oil spill recovery robot

Science.gov (United States)

Zhang, Min-ge; Wu, Jian-guo; Lin, Xinhua; Wang, Xiao-ming

2018-03-01

Oil spill have the most common pollution to the marine ecological environment. In the late stage of physical method recovery, because of the thin oil and the strong sea breeze, the recovery vessels has low efficiency and high energy consumption. This paper develops a multi-stage oil-water-separating process carried by the sea oil spill recovery robot in severe conditions. This design consists of three separation process, among which both the first and third process adopt corrugated sheets horizontal oil-water separator, while the second is hydraulic rotary breaker. This design also equiptment with rectifier and cyclone separator and other important components. This process has high flexibility and high recovery efficiency. The implement effect is significant.

Interconnected levels of multi-stage marketing: A triadic approach

OpenAIRE

Vedel, Mette; Geersbro, Jens; Ritter, Thomas

2012-01-01

Multi-stage marketing gains increasing attention as knowledge of and influence on the customer's customer become more critical for the firm's success. Despite this increasing managerial relevance, systematic approaches for analyzing multi-stage marketing are still missing. This paper conceptualizes different levels of multi-stage marketing and illustrates these stages with a case study. In addition, a triadic perspective is introduced as an analytical tool for multi-stage marketing research. ...

Danube paleohydrology: Hyperspectral and sedimentological high-resultion study of the last glacial Black Sea rythmites

Science.gov (United States)

Martinez Lamas, R.; Debret, M.; Deloffre, J.; Toucanne, S.

2017-12-01

The Black Sea has undergone alternating phases of lacustrine and marine environment over geological timescales directly related to its semi-enclosed character and to eustatic sea-level oscillations. During lowstand conditions, as during the last glacial period, the Black Sea was a giant lake disconnected from the global ocean. At that time, Black Sea water-level was controlled by regional climate, and by Eurasian rivers, including the Danube that acted as an outlet of European Ice Sheet and the Alpine ice cap. Thus, the paleo-mouth of the Danube river contains a high quality archive for the study of the paleohydrology of the Danube River and by extension of the European climate changes during the last 30 kyr. For this purpose, we have focused on the GAS-CS01 calypso long-piston core (33.4 m) which was taken during GHASS cruise (Ifremer, 2015) on the upper slope (240 m. depth) at about 25 km east of the Danube Canyon, i.e. in the sediment pile of the Danube paleo-mouth during the last glacial period. Our chronology reveals that core GAS-CS01 extends back to 31 cal kyr BP. The lithology of GAS-CS01 is characterized by clastic rythmites which are presented as a high-resolution Danube runoff proxy. Preliminary results of sedimentological and chronological analysis showed five peaks of terrestrial discharges between ca 31 and 14 ka BP, probably linked to five phases of the enhanced runoff during the studied period. In order to understand the origin and the depositional processes of this laminae, we combined sedimentary analysis (x-ray diffraction, x-ray fluorescence, grain size ...) and hyperspectral images analysis. Hyperspectral imagery is a non-destructive fast method classically used to quantify colour and provides data with high spatial (57-µm pixel size) and spectral (3 nm) resolution. The multi-proxy calibration is essential in order to obtain a high-resolution sedimentological dataset. This information allows us to reconstruct the nature and depositional

Growth rates and geochemical proxies in Late Campanian bivalves - New insights from micro-X-ray Fluorescence mapping and numerical growth modelling

Science.gov (United States)

de Winter, Niels; Goderis, Steven; van Malderen, Stijn; Vanhaecke, Frank; Claeys, Philippe

2017-04-01

Understanding the Late Cretaceous greenhouse climate is of vital importance for understanding present and future climate change. While a lot of good work has been done to reconstruct climate in this interesting period, most paleoclimatic studies have focused on long-term climate change[1]. Alternatively, multi-proxy records from marine bivalves provide us with a unique opportunity to study past climate on a seasonal scale. However, previous fossil bivalve studies have reported ambiguous results with regard to the interpretation of trace element and stable isotope proxies in marine bivalve shells[2]. One major problem in the interpretation of such records is the bivalve's vital effect and the occurrence of disequilibrium fractionation during bivalve growth. Both these problems are linked to the annual growth cycle of marine bivalves, which introduces internal effects on the incorporation of isotopes and trace elements into the shell[3]. Understanding this growth cycle in extinct bivalves is therefore of great importance for the interpretation of seasonal proxy records in their shells. In this study, three different species of extinct Late Campanian bivalves (two rudist species and one oyster species) that were found in the same stratigraphic interval are studied. Micro-X-Ray Fluorescence line scanning and mapping of trace elements such as Mg, Sr, S and Zn, calibrated by LA-ICP-MS measurements, is combined with microdrilled stable carbon and oxygen isotope analysis on the well-preserved part of the shells. Data of this multi-proxy study is compared with results from a numerical growth model written in the open-source statistics package R[4] and based on annual growth increments observed in the shells and shell thickness. This growth model is used together with proxy data to reconstruct rates of trace element incorporation into the shell and to calculate the mass balance of stable oxygen and carbon isotopes. In order to achieve this goal, 2D mapping of bivalve shell

Incentive-based approaches in marine conservation: Applications for sea turtles

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Gjertsen Heidi

2010-01-01

Full Text Available Conservation practitioners are increasingly turning to incentive-based approaches to encourage local resource users to change behaviors that impact biodiversity and natural habitat. We assess the design and performance of marine conservation interventions with varying types of incentives through an analysis of case studies from around the world. Here we focus on seven examples that are particularly relevant to designing incentives for sea turtle conservation. Four of the cases are focused on sea turtle conservation, and the others contain elements that may be applied to turtle projects. Many more opportunities exist for interventions that combine the strengths of these approaches, such as performance-based agreements that provide funds for education or alternative livelihood development, and leasing fishing rights to reduce bycatch.

Advantages of Task-Specific Multi-Objective Optimisation in Evolutionary Robotics.

Science.gov (United States)

Trianni, Vito; López-Ibáñez, Manuel

2015-01-01

The application of multi-objective optimisation to evolutionary robotics is receiving increasing attention. A survey of the literature reveals the different possibilities it offers to improve the automatic design of efficient and adaptive robotic systems, and points to the successful demonstrations available for both task-specific and task-agnostic approaches (i.e., with or without reference to the specific design problem to be tackled). However, the advantages of multi-objective approaches over single-objective ones have not been clearly spelled out and experimentally demonstrated. This paper fills this gap for task-specific approaches: starting from well-known results in multi-objective optimisation, we discuss how to tackle commonly recognised problems in evolutionary robotics. In particular, we show that multi-objective optimisation (i) allows evolving a more varied set of behaviours by exploring multiple trade-offs of the objectives to optimise, (ii) supports the evolution of the desired behaviour through the introduction of objectives as proxies, (iii) avoids the premature convergence to local optima possibly introduced by multi-component fitness functions, and (iv) solves the bootstrap problem exploiting ancillary objectives to guide evolution in the early phases. We present an experimental demonstration of these benefits in three different case studies: maze navigation in a single robot domain, flocking in a swarm robotics context, and a strictly collaborative task in collective robotics.

Advantages of Task-Specific Multi-Objective Optimisation in Evolutionary Robotics.

Directory of Open Access Journals (Sweden)

Vito Trianni

Full Text Available The application of multi-objective optimisation to evolutionary robotics is receiving increasing attention. A survey of the literature reveals the different possibilities it offers to improve the automatic design of efficient and adaptive robotic systems, and points to the successful demonstrations available for both task-specific and task-agnostic approaches (i.e., with or without reference to the specific design problem to be tackled. However, the advantages of multi-objective approaches over single-objective ones have not been clearly spelled out and experimentally demonstrated. This paper fills this gap for task-specific approaches: starting from well-known results in multi-objective optimisation, we discuss how to tackle commonly recognised problems in evolutionary robotics. In particular, we show that multi-objective optimisation (i allows evolving a more varied set of behaviours by exploring multiple trade-offs of the objectives to optimise, (ii supports the evolution of the desired behaviour through the introduction of objectives as proxies, (iii avoids the premature convergence to local optima possibly introduced by multi-component fitness functions, and (iv solves the bootstrap problem exploiting ancillary objectives to guide evolution in the early phases. We present an experimental demonstration of these benefits in three different case studies: maze navigation in a single robot domain, flocking in a swarm robotics context, and a strictly collaborative task in collective robotics.

SEAS: A simulated evolution approach for analog circuit synthesis

NARCIS (Netherlands)

Ning, Zhen-Qiu; Ning, Zhen-Qiu; Mouthaan, A.J.; Wallinga, Hans

1991-01-01

The authors present a simulated evolution approach for analog circuit synthesis based on an analogy with the natural selection process in biological environments and on the iterative improvements in solving engineering problems. A prototype framework based on this idea, called SEAS, has been

Multiple oscillations during the Lateglacial as recorded in a multi-proxy, high-resolution record of the Moervaart palaeolake (NW Belgium)

Science.gov (United States)

Bos, Johanna A. A.; De Smedt, Philippe; Demiddele, Hendrik; Hoek, Wim Z.; Langohr, Roger; Marcelino, Vera; Van Asch, Nelleke; Van Damme, Dirk; Van der Meeren, Thijs; Verniers, Jacques; Boeckx, Pascal; Boudin, Mathieu; Court-Picon, Mona; Finke, Peter; Gelorini, Vanessa; Gobert, Stefan; Heiri, Oliver; Martens, Koen; Mostaert, Frank; Serbruyns, Lynn; Van Strydonck, Mark; Crombé, Philippe

2017-04-01

This paper presents the results of multi-disciplinary research carried out on the deposits of Moervaart depression, NW Belgium, one of the largest palaeolakes (∼25 km2) that existed during the Lateglacial interstadial in NW Europe. The multi-proxy study, including physical (organic matter and calcium carbonate, magnetic susceptibility, micromorphological), botanical (pollen, macrofossils, diatoms), zoological (ostracods, molluscs, chironomids) and chemical analyses (stable carbon and oxygen isotopes) has resulted in a detailed reconstruction of the Lateglacial landscape as well of the local conditions that prevailed in the lake itself. A chronology of the record was provided by radiocarbon dating and comparison with radiocarbon dates of the nearby Rieme site. These yielded a good match with the regional biostratigraphy. During the Lateglacial, vegetation and geomorphology of the landscape in general changed from a tundra landscape to a boreal forest. The vegetation development, however, was interrupted by a number of cold reversals. Three centennial-scale cold oscillations are present in the record: 1) the so-called Older Dryas corresponding to GI-1d in the Greenland ice-cores, 2) a short and pronounced cold event during the early Allerød, which could be correlated to GI-1c2 and 3) a cooling event during the late Allerød probably corresponding to the Intra Allerød Cold Period (IACP) or GI-1b. The latter most likely was responsible for the disappearance of the Moervaart palaeolake.

Land–sea coupling of early Pleistocene glacial cycles in the southern North Sea exhibit dominant Northern Hemisphere forcing

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T. H. Donders

2018-03-01

Full Text Available We assess the disputed phase relations between forcing and climatic response in the early Pleistocene with a spliced Gelasian (∼ 2.6–1.8 Ma multi-proxy record from the southern North Sea basin. The cored sections couple climate evolution on both land and sea during the intensification of Northern Hemisphere glaciation (NHG in NW Europe, providing the first well-constrained stratigraphic sequence of the classic terrestrial Praetiglian stage. Terrestrial signals were derived from the Eridanos paleoriver, a major fluvial system that contributed a large amount of freshwater to the northeast Atlantic. Due to its latitudinal position, the Eridanos catchment was likely affected by early Pleistocene NHG, leading to intermittent shutdown and reactivation of river flow and sediment transport. Here we apply organic geochemistry, palynology, carbonate isotope geochemistry, and seismostratigraphy to document both vegetation changes in the Eridanos catchment and regional surface water conditions and relate them to early Pleistocene glacial–interglacial cycles and relative sea level changes. Paleomagnetic and palynological data provide a solid integrated timeframe that ties the obliquity cycles, expressed in the borehole geophysical logs, to Marine Isotope Stages (MIS 103 to 92, independently confirmed by a local benthic oxygen isotope record. Marine and terrestrial palynological and organic geochemical records provide high-resolution reconstructions of relative terrestrial and sea surface temperature (TT and SST, vegetation, relative sea level, and coastal influence.During the prominent cold stages MIS 98 and 96, as well as 94, the record indicates increased non-arboreal vegetation, low SST and TT, and low relative sea level. During the warm stages MIS 99, 97, and 95 we infer increased stratification of the water column together with a higher percentage of arboreal vegetation, high SST, and relative sea level maxima. The early Pleistocene distinct

Rapid discrimination of sea buckthorn berries from different H. rhamnoides subspecies by multi-step IR spectroscopy coupled with multivariate data analysis

Science.gov (United States)

Liu, Yue; Zhang, Ying; Zhang, Jing; Fan, Gang; Tu, Ya; Sun, Suqin; Shen, Xudong; Li, Qingzhu; Zhang, Yi

2018-03-01

As an important ethnic medicine, sea buckthorn was widely used to prevent and treat various diseases due to its nutritional and medicinal properties. According to the Chinese Pharmacopoeia, sea buckthorn was originated from H. rhamnoides, which includes five subspecies distributed in China. Confusion and misidentification usually occurred due to their similar morphology, especially in dried and powdered forms. Additionally, these five subspecies have vital differences in quality and physiological efficacy. This paper focused on the quick classification and identification method of sea buckthorn berry powders from five H. rhamnoides subspecies using multi-step IR spectroscopy coupled with multivariate data analysis. The holistic chemical compositions revealed by the FT-IR spectra demonstrated that flavonoids, fatty acids and sugars were the main chemical components. Further, the differences in FT-IR spectra regarding their peaks, positions and intensities were used to identify H. rhamnoides subspecies samples. The discrimination was achieved using principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA). The results showed that the combination of multi-step IR spectroscopy and chemometric analysis offered a simple, fast and reliable method for the classification and identification of the sea buckthorn berry powders from different H. rhamnoides subspecies.

A Delphi-matrix approach to SEA and its application within the tourism sector in Taiwan

International Nuclear Information System (INIS)

Kuo, N.-W.; Hsiao, T.-Y.; Yu, Y.-H.

2005-01-01

Strategic Environmental Assessment (SEA) is a procedural tool and within the framework of SEA, several different types of analytical methods can be used in the assessment. However, the impact matrix used currently in Taiwan has some disadvantages. Hence, a Delphi-matrix approach to SEA is proposed here to improve the performance of Taiwan's SEA. This new approach is based on the impact matrix combination with indicators of sustainability, and then the Delphi method is employed to collect experts' opinions. In addition, the assessment of National Floriculture Park Plan and Taiwan Flora 2008 Program is taken as an example to examine this new method. Although international exhibition is one of the important tourism (economic) activities, SEA is seldom about tourism sector. Finally, the Delphi-matrix approach to SEA for tourism development plan is established containing eight assessment topics and 26 corresponding categories. In summary, three major types of impacts: resources' usages, pollution emissions, and local cultures change are found. Resources' usages, such as water, electricity, and natural gas demand, are calculated on a per capita basis. Various forms of pollution resulting from this plan, such as air, water, soil, waste, and noise, are also identified

Reservoir age variations and stable isotope values of bulk sediment in a core from the Limfjord, Denmark

DEFF Research Database (Denmark)

Philippsen, Bente; Olsen, Jesper; Rasmussen, Peter

The Limfjord is a sound in Northern Jutland, Denmark, connecting the North Sea with the Kattegat. A multi-proxy approach has been applied to a sediment core from Kilen, a former fjord arm near the town of Struer, to reveal the Limfjord’s development in more detail. In this paper, we concentrate...... on radiocarbon dating of shells and on stable isotope measurements of bulk sediment from 7400 to 1300 cal BP. Reservoir ages in coastal waters and estuaries can differ considerably from the global model ocean. The seas around Denmark have a reservoir age of c. 400 years, while a hardwater effect of a few...... of organic matter can thus be estimated. The d13C and C/N inferred salinity can be related to changes in Delta-R and other palaeoenvironmental proxies. An increasing marine influence throughout the largest part of the core is followed by large variations around 2000 cal BP....

Short Communication: Growth of seaweed Eucheuma cottonii in multi trophic sea farming systems at Gerupuk Bay, Central Lombok, Indonesia

Directory of Open Access Journals (Sweden)

SUKIMAN

2014-05-01

Full Text Available Sukiman, Faturrahman, Rohyani IS, Ahyadi H. 2014. Growth of seaweed Eucheuma cottonii in multi trophic sea farming systems at Gerupuk Bay, Central Lombok, Indonesia. Nusantara Bioscience 6: 82-85. Eucheuma cottonii is a seaweed commodity that has a high economic value because it contains compounds used as raw materials for industries. Various methods of seaweed farming have been developed, one of which is a system of cultivation Multi Trophic Sea Farming. This study aimed to analyze the growth of E. cottonii by observing the production of biomass in four trophic combinations in the system Multi Trophic Sea Farming. The study was conducted in the area of the marine aquaculture Gerupuk bay, Central Lombok, Indonesia. Experiments were performed on four plots cages with trophic combination treatment as follows: K1 (E. cottonii-lobster-abalone, K2 (E. cottonii-abalone-red carp, K3 (E. cottonii-abalone-grouper, and K4 (E. cottonii-abalone-pomfret fish. Seedling of E. cottonii weighing 50 g was tied to a rope and placed at a depth of 5 cm, 50 cm, 100 cm and 150 cm. Measurement of biomass production was done every ten days until the thirtieth day. The highest biomass production of E. cottonii was obtained in K3 trophic combination (E. cottonii-abalone-grouper fish with a depth of seedlings of 5 cm. The combination of K3 trophic is recommended for cultivation of seaweed in the MTSF system.

FGP Approach for Solving Multi-level Multi-objective Quadratic Fractional Programming Problem with Fuzzy parameters

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m. s. osman

2017-09-01

Full Text Available In this paper, we consider fuzzy goal programming (FGP approach for solving multi-level multi-objective quadratic fractional programming (ML-MOQFP problem with fuzzy parameters in the constraints. Firstly, the concept of the ?-cut approach is applied to transform the set of fuzzy constraints into a common deterministic one. Then, the quadratic fractional objective functions in each level are transformed into quadratic objective functions based on a proposed transformation. Secondly, the FGP approach is utilized to obtain a compromise solution for the ML-MOQFP problem by minimizing the sum of the negative deviational variables. Finally, an illustrative numerical example is given to demonstrate the applicability and performance of the proposed approach.

A scenario framework to explore the future migration and adaptation in deltas: A multi-scale and participatory approach

Science.gov (United States)

Kebede, Abiy S.; Nicholls, Robert J.; Allan, Andrew; Arto, Inaki; Cazcarro, Ignacio; Fernandes, Jose A.; Hill, Chris T.; Hutton, Craig W.; Kay, Susan; Lawn, Jon; Lazar, Attila N.; Whitehead, Paul W.

2017-04-01

Coastal deltas are home for over 500 million people globally, and they have been identified as one of the most vulnerable coastal environments during the 21st century. They are susceptible to multiple climatic (e.g., sea-level rise, storm surges, change in temperature and precipitation) and socio-economic (e.g., human-induced subsidence, population and urbanisation changes, GDP growth) drivers of change. These drivers also operate at multiple scales, ranging from local to global and short- to long-term. This highlights the complex challenges deltas face in terms of both their long-term sustainability as well as the well-being of their residents and the health of ecosystems that support the livelihood of large (often very poor) population under uncertain changing conditions. A holistic understanding of these challenges and the potential impacts of future climate and socio-economic changes is central for devising robust adaptation policies. Scenario analysis has long been identified as a strategic management tool to explore future climate change and its impacts for supporting robust decision-making under uncertainty. This work presents the overall scenario framework, methodology, and processes adopted for the development of scenarios in the DECCMA* project. DECCMA is analysing the future of three deltas in South Asia and West Africa: (i) the Ganges-Brahmaputra-Meghna (GBM) delta (Bangladesh/India), (ii) the Mahanadi delta (India), and (iii) the Volta delta (Ghana). This includes comparisons between these three deltas. Hence, the scenario framework comprises a multi-scale hybrid approach, with six levels of scenario considerations: (i) global (climate change, e.g., sea-level rise, temperature change; and socio-economic assumptions, e.g., population and urbanisation changes, GDP growth); (ii) regional catchments (e.g., river flow modelling), (iii) regional seas (e.g., fisheries modelling), (iv) regional politics (e.g., transboundary disputes), (v) national (e.g., socio

Multi-level approach for parametric roll analysis

Science.gov (United States)

Kim, Taeyoung; Kim, Yonghwan

2011-03-01

The present study considers multi-level approach for the analysis of parametric roll phenomena. Three kinds of computation method, GM variation, impulse response function (IRF), and Rankine panel method, are applied for the multi-level approach. IRF and Rankine panel method are based on the weakly nonlinear formulation which includes nonlinear Froude- Krylov and restoring forces. In the computation result of parametric roll occurrence test in regular waves, IRF and Rankine panel method show similar tendency. Although the GM variation approach predicts the occurrence of parametric roll at twice roll natural frequency, its frequency criteria shows a little difference. Nonlinear roll motion in bichromatic wave is also considered in this study. To prove the unstable roll motion in bichromatic waves, theoretical and numerical approaches are applied. The occurrence of parametric roll is theoretically examined by introducing the quasi-periodic Mathieu equation. Instability criteria are well predicted from stability analysis in theoretical approach. From the Fourier analysis, it has been verified that difference-frequency effects create the unstable roll motion. The occurrence of unstable roll motion in bichromatic wave is also observed in the experiment.

Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach

Science.gov (United States)

Sacco, Alexander Edward

The goal of this thesis is to define specific parameters of mesoscale sea-ice seascapes for which walruses show preference during important periods of their natural history. This research thesis incorporates sea-ice geophysics, marine-mammal ecology, remote sensing, computer vision techniques, and traditional ecological knowledge of indigenous subsistence hunters in order to quantitatively study walrus preference of sea ice during the spring migration in the Bering Sea. Using an approach that applies seascape ecology, or landscape ecology to the marine environment, our goal is to define specific parameters of ice patch descriptors, or mesoscale seascapes in order to evaluate and describe potential walrus preference for such ice and the ecological services it provides during an important period of their life-cycle. The importance of specific sea-ice properties to walrus occupation motivates an investigation into how walruses use sea ice at multiple spatial scales when previous research suggests that walruses do not show preference for particular floes. Analysis of aerial imagery, using image processing techniques and digital geomorphometric measurements (floe size, shape, and arrangement), demonstrated that while a particular floe may not be preferred, at larger scales a collection of floes, specifically an ice patch (cross-cultural sea-ice observations, knowledge and science to determine sea ice importance to marine mammals in a changing Arctic.

A Multi-organisational Approach to Service Delivery

Science.gov (United States)

Purchase, Valerie; Mills, John; Parry, Glenn

Who is involved in delivering a service? There has been growing recognition in a wide variety of contexts that service is increasingly being delivered by multi-rather than single-organisational entities. Such recognition is evident not only in our experience but in a number of areas of literature including strategy development, core competence analysis, operations and supply chain management, and is reflected in and further facilitated by ICT developments. Customers have always been involved in some degree in the process of value delivery and such involvement is increasing to include complex co-creation of value. Such interactions are challenging when they involve individual customers, however, this becomes ever more challenging when the 'customer' is another organisation or when there are multiple 'customers'. Within this chapter we will consider some of the key drivers for a multi-organisational approach to service delivery; examine the ways in which the parties involved in service co-creation have expanded to include multiple service providers and customers; and finally, identify some of the challenges created by a multi-organisational approach to service delivery.

Management-focused approach to investigating coastal water-quality drivers and impacts in the Baltic Sea

Science.gov (United States)

Vigouroux, G.; Destouni, G.; Chen, Y.; Bring, A.; Jönsson, A.; Cvetkovic, V.

2017-12-01

Coastal areas link human-driven conditions on land with open sea conditions, and include crucial and vulnerable ecosystems that provide a variety of ecosystem services. Eutrophication is a common problem that is not least observed in the Baltic Sea, where coastal water quality is influenced both by land-based nutrient loading and by partly eutrophic open sea conditions. Robust and adaptive management of coastal systems is essential and necessitates integration of large scale catchment-coastal-marine systems as well as consideration of anthropogenic drivers and impacts, and climate change. To address this coastal challenge, relevant methodological approaches are required for characterization of coupled land, local coastal, and open sea conditions under an adaptive management framework for water quality. In this paper we present a new general and scalable dynamic characterization approach, developed for and applied to the Baltic Sea and its coastal areas. A simple carbon-based water quality model is implemented, dividing the Baltic Sea into main management basins that are linked to corresponding hydrological catchments on land, as well as to each other though aggregated three-dimensional marine hydrodynamics. Relevant hydrodynamic variables and associated water quality results have been validated on the Baltic Sea scale and show good accordance with available observation data and other modelling approaches. Based on its scalability, this methodology is further used on coastal zone scale to investigate the effects of hydrodynamic, hydro-climatic and nutrient load drivers on water quality and management implications for coastal areas in the Baltic Sea.

Multi-Decadal Coastal Behavioural States From A Fusion Of Geohistorical Conceptual Modelling With 2-D Morphodynamic Modelling

Science.gov (United States)

Goodwin, I. D.; Mortlock, T.

2016-02-01

Geohistorical archives of shoreline and foredune planform geometry provides a unique evidence-based record of the time integral response to coupled directional wave climate and sediment supply variability on annual to multi-decadal time scales. We develop conceptual shoreline modelling from the geohistorical shoreline archive using a novel combination of methods, including: LIDAR DEM and field mapping of coastal geology; a decadal-scale climate reconstruction of sea-level pressure, marine windfields, and paleo-storm synoptic type and frequency, and historical bathymetry. The conceptual modelling allows for the discrimination of directional wave climate shifts and the relative contributions of cross-shore and along-shore sand supply rates at multi-decadal resolution. We present regional examples from south-eastern Australia over a large latitudinal gradient from subtropical Queensland (S 25°) to mid-latitude Bass Strait (S 40°) that illustrate the morphodynamic evolution and reorganization to wave climate change. We then use the conceptual modeling to inform a two-dimensional coupled spectral wave-hydrodynamic-morphodynamic model to investigate the shoreface response to paleo-directional wind and wave climates. Unlike one-line shoreline modelling, this fully dynamical approach allows for the investigation of cumulative and spatial bathymetric change due to wave-induced currents, as well as proxy-shoreline change. The fusion of the two modeling approaches allows for: (i) the identification of the natural range of coastal planform geometries in response to wave climate shifts; and, (ii) the decomposition of the multidecadal coastal change into the cross-shore and along-shore sand supply drivers, according to the best-matching planforms.

The generation and re-generation of social capital and enterprises in multi-stakeholders social cooperative enterprises: a system dynamic approach

Directory of Open Access Journals (Sweden)

Claudio Travaglini

2012-09-01

Full Text Available Theories on social capital and on social entrepreneurship have mainly highlighted the attitude of social capital to generate enterprises and to foster good relations between third sector organizations and the public sector. This paper considers the social capital in a specific third sector enterprise; here, multi-stakeholder social cooperatives are seen, at the same time, as social capital results, creators and incubators. In the particular enterprises that identify themselves as community social enterprises, social capital, both as organizational and relational capital, is fundamental: SCEs arise from but also produce and disseminate social capital. This paper aims to improve the building of relational social capital and the refining of helpful relations drawn from other arenas, where they were created and from where they are sometimes transferred to other realities, where their role is carried on further (often working in non-profit, horizontally and vertically arranged groups, where they share resources and relations. To represent this perspective, we use a qualitative system dynamic approach in which social capital is measured using proxies. Cooperation of volunteers, customers, community leaders and third sector local organizations is fundamental to establish trust relations between public local authorities and cooperatives. These relations help the latter to maintain long-term contracts with local authorities as providers of social services and enable them to add innovation to their services, by developing experiences and management models and maintaining an interchange with civil servants regarding these matters. The long-term relations and the organizational relations linking SCEs and public organizations help to create and to renovate social capital. Thus, multi-stakeholder cooperatives originated via social capital developed in third sector organizations produce new social capital within the cooperatives themselves and between

Multi-criteria multi-stakeholder decision analysis using a fuzzy-stochastic approach for hydrosystem management

Science.gov (United States)

Subagadis, Y. H.; Schütze, N.; Grundmann, J.

2014-09-01

The conventional methods used to solve multi-criteria multi-stakeholder problems are less strongly formulated, as they normally incorporate only homogeneous information at a time and suggest aggregating objectives of different decision-makers avoiding water-society interactions. In this contribution, Multi-Criteria Group Decision Analysis (MCGDA) using a fuzzy-stochastic approach has been proposed to rank a set of alternatives in water management decisions incorporating heterogeneous information under uncertainty. The decision making framework takes hydrologically, environmentally, and socio-economically motivated conflicting objectives into consideration. The criteria related to the performance of the physical system are optimized using multi-criteria simulation-based optimization, and fuzzy linguistic quantifiers have been used to evaluate subjective criteria and to assess stakeholders' degree of optimism. The proposed methodology is applied to find effective and robust intervention strategies for the management of a coastal hydrosystem affected by saltwater intrusion due to excessive groundwater extraction for irrigated agriculture and municipal use. Preliminary results show that the MCGDA based on a fuzzy-stochastic approach gives useful support for robust decision-making and is sensitive to the decision makers' degree of optimism.

Application Of Multi-grid Method On China Seas' Temperature Forecast

Science.gov (United States)

Li, W.; Xie, Y.; He, Z.; Liu, K.; Han, G.; Ma, J.; Li, D.

2006-12-01

Correlation scales have been used in traditional scheme of 3-dimensional variational (3D-Var) data assimilation to estimate the background error covariance for the numerical forecast and reanalysis of atmosphere and ocean for decades. However there are still some drawbacks of this scheme. First, the correlation scales are difficult to be determined accurately. Second, the positive definition of the first-guess error covariance matrix cannot be guaranteed unless the correlation scales are sufficiently small. Xie et al. (2005) indicated that a traditional 3D-Var only corrects some certain wavelength errors and its accuracy depends on the accuracy of the first-guess covariance. And in general, short wavelength error can not be well corrected until long one is corrected and then inaccurate first-guess covariance may mistakenly take long wave error as short wave ones and result in erroneous analysis. For the purpose of quickly minimizing the errors of long and short waves successively, a new 3D-Var data assimilation scheme, called multi-grid data assimilation scheme, is proposed in this paper. By assimilating the shipboard SST and temperature profiles data into a numerical model of China Seas, we applied this scheme in two-month data assimilation and forecast experiment which ended in a favorable result. Comparing with the traditional scheme of 3D-Var, the new scheme has higher forecast accuracy and a lower forecast Root-Mean-Square (RMS) error. Furthermore, this scheme was applied to assimilate the SST of shipboard, AVHRR Pathfinder Version 5.0 SST and temperature profiles at the same time, and a ten-month forecast experiment on sea temperature of China Seas was carried out, in which a successful forecast result was obtained. Particularly, the new scheme is demonstrated a great numerical efficiency in these analyses.

Impact of water depth on the distribution of iGDGTs in the surface sediments from the northern South China Sea: applicability of TEX86 in marginal seas

Science.gov (United States)

Chen, Jiali; Hu, Pengju; Li, Xing; Yang, Yang; Song, Jinming; Li, Xuegang; Yuan, Huamao; Li, Ning; Lü, Xiaoxia

2018-03-01

The TEX 86 H paleothermometer on the base of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) has been widely applied to various marine settings to reconstruct past sea surface temperatures (SSTs). However, it remains uncertain how well this proxy reconstructs SSTs in marginal seas. In this study, we analyze the environmental factors governing distribution of iGDGTs in surface sediments to assess the applicability of TEX 86 H paleothermometer in the South China Sea (SCS). Individual iGDGT concentrations increase gradually eastwards. Redundancy analysis based on the relative abundance of an individual iGDGT compound and environmental parameters suggests that water depth is the most influential factor to the distribution of iGDGTs, because thaumarchaeota communities are water-depth dependent. Interestingly, the SST difference (Δ T) between TEX 86 H derived temperature and remote-sensing SST is less than 1°C in sediments with water depth>200 m, indicating that TEX 86 H was the robust proxy to trace the paleo-SST in the region if water depth is greater than 200 m.

Multi-proxy reconstructions of May–September precipitation field in China over the past 500 years

Directory of Open Access Journals (Sweden)

F. Shi

2017-12-01

Full Text Available The dominant modes of variability of precipitation for the whole of China over the past millennium and the mechanism governing their spatial structure remain unclear. This is mainly due to insufficient high-resolution proxy records of precipitation in western China. Numerous tree-ring chronologies have recently been archived in publicly available databases through PAGES2k activities, and these provide an opportunity to refine precipitation field reconstructions for China. Based on 479 proxy records, including 371 tree-ring width chronologies, a tree-ring isotope chronology, and 107 drought/flood indices, we reconstruct the precipitation field for China for the past half millennium using the optimal information extraction method. A total of 3631 of 4189 grid points in the reconstruction field passed the cross-validation process, accounting for 86.68 % of the total number of grid points. The first leading mode of variability of the reconstruction shows coherent variations over most of China. The second mode is a north–south dipole in eastern China characterized by variations of the same sign in western China and northern China (except for Xinjiang province. It is likely controlled by the El Niño–Southern Oscillation (ENSO variability. The third mode is a sandwich triple mode in eastern China including variations of the same sign in western China and central China. The last two modes are reproduced by most of the six coupled climate models' last millennium simulations performed in the framework of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3. In particular, the link of the second mode with ENSO is confirmed by the models. However, there is a mismatch between models and proxy reconstructions in the time development of different modes. This mismatch suggests the important role of internal variability in the reconstructed precipitation mode variations of the past 500 years.

Multi-proxy reconstructions of May-September precipitation field in China over the past 500 years

Science.gov (United States)

Shi, Feng; Zhao, Sen; Guo, Zhengtang; Goosse, Hugues; Yin, Qiuzhen

2017-12-01

The dominant modes of variability of precipitation for the whole of China over the past millennium and the mechanism governing their spatial structure remain unclear. This is mainly due to insufficient high-resolution proxy records of precipitation in western China. Numerous tree-ring chronologies have recently been archived in publicly available databases through PAGES2k activities, and these provide an opportunity to refine precipitation field reconstructions for China. Based on 479 proxy records, including 371 tree-ring width chronologies, a tree-ring isotope chronology, and 107 drought/flood indices, we reconstruct the precipitation field for China for the past half millennium using the optimal information extraction method. A total of 3631 of 4189 grid points in the reconstruction field passed the cross-validation process, accounting for 86.68 % of the total number of grid points. The first leading mode of variability of the reconstruction shows coherent variations over most of China. The second mode is a north-south dipole in eastern China characterized by variations of the same sign in western China and northern China (except for Xinjiang province). It is likely controlled by the El Niño-Southern Oscillation (ENSO) variability. The third mode is a sandwich triple mode in eastern China including variations of the same sign in western China and central China. The last two modes are reproduced by most of the six coupled climate models' last millennium simulations performed in the framework of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3). In particular, the link of the second mode with ENSO is confirmed by the models. However, there is a mismatch between models and proxy reconstructions in the time development of different modes. This mismatch suggests the important role of internal variability in the reconstructed precipitation mode variations of the past 500 years.

Sea surface temperature and sea ice variability in the subpolar North Atlantic from explosive volcanism of the late thirteenth century

DEFF Research Database (Denmark)

Sicre, M. -A.; Khodri, M.; Mignot, J.

2013-01-01

In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short-and long......-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling...... and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades....

Bathymetric controls on Pliocene North Atlantic and Arctic sea surface temperature and deepwater production

Science.gov (United States)

Robinson, M.M.; Valdes, P.J.; Haywood, A.M.; Dowsett, H.J.; Hill, D.J.; Jones, S.M.

2011-01-01

The mid-Pliocene warm period (MPWP; ~. 3.3 to 3.0. Ma) is the most recent interval in Earth's history in which global temperatures reached and remained at levels similar to those projected for the near future. The distribution of global warmth, however, was different than today in that the high latitudes warmed more than the tropics. Multiple temperature proxies indicate significant sea surface warming in the North Atlantic and Arctic Oceans during the MPWP, but predictions from a fully coupled ocean-atmosphere model (HadCM3) have so far been unable to fully predict the large scale of sea surface warming in the high latitudes. If climate proxies accurately represent Pliocene conditions, and if no weakness exists in the physics of the model, then model boundary conditions may be in error. Here we alter a single boundary condition (bathymetry) to examine if Pliocene high latitude warming was aided by an increase in poleward heat transport due to changes in the subsidence of North Atlantic Ocean ridges. We find an increase in both Arctic sea surface temperature and deepwater production in model experiments that incorporate a deepened Greenland-Scotland Ridge. These results offer both a mechanism for the warming in the North Atlantic and Arctic Oceans indicated by numerous proxies and an explanation for the apparent disparity between proxy data and model simulations of Pliocene northern North Atlantic and Arctic Ocean conditions. Determining the causes of Pliocene warmth remains critical to fully understanding comparisons of the Pliocene warm period to possible future climate change scenarios. ?? 2011.

Multi-species spawning synchrony within scleractinian coral assemblages in the Red Sea

KAUST Repository

Bouwmeester, Jessica; Baird, Andrew Hamilton; Chen, C. J.; Guest, James R.; Vicentuan, Kareen C.; Berumen, Michael L.

2014-01-01

Early work on coral reproduction in the far northern Red Sea suggested that the spawning times of ecologically abundant species did not overlap, unlike on the Great Barrier Reef where many species spawn with high synchrony. In contrast, recent work in the northern and central Red Sea indicates a high degree of synchrony in the reproductive condition of Acropora species: over 90 % of species sampled in April/May contain mature gametes. However, it has yet to be determined when most Acropora release their gametes. In addition, there is a lack of data for other ecologically important scleractinian species such as merulinids and poritids. Here, we document the date and time of spawning for 51 species in the central Red Sea over three consecutive years, and the month of spawning for an additional 17 species inferred from the presence of mature gametes. Spawning occurs on nights around the full moon, the spawning season lasts at least 4 months from April until July, and observations are consistent with the few other records from the Red Sea. The number of Acropora species spawning was highest in April with 13 species spawning two nights before the full moon in 2011, 13 species spawning on the night of the full moon in 2012, and eight species spawning four nights after the full moon in 2013. The total number of species spawning was high in April, May, and June and involved 15–19 species per month in 2012. Only four species spawned in July 2012. Few regions worldwide have been similarly sampled and include the Philippines, Okinawa in Japan, and Palau, where spawning patterns are very similar to those in the central Red Sea and where corals spawn on nights around the full moon over a period of 3–4 months. In particular, in all four locations, Acropora are among the first species to spawn. Our results add to a growing body of evidence indicating that multi-species spawning synchrony is a feature of all speciose coral assemblages.

Multi-species spawning synchrony within scleractinian coral assemblages in the Red Sea

KAUST Repository

Bouwmeester, Jessica

2014-09-21

Early work on coral reproduction in the far northern Red Sea suggested that the spawning times of ecologically abundant species did not overlap, unlike on the Great Barrier Reef where many species spawn with high synchrony. In contrast, recent work in the northern and central Red Sea indicates a high degree of synchrony in the reproductive condition of Acropora species: over 90 % of species sampled in April/May contain mature gametes. However, it has yet to be determined when most Acropora release their gametes. In addition, there is a lack of data for other ecologically important scleractinian species such as merulinids and poritids. Here, we document the date and time of spawning for 51 species in the central Red Sea over three consecutive years, and the month of spawning for an additional 17 species inferred from the presence of mature gametes. Spawning occurs on nights around the full moon, the spawning season lasts at least 4 months from April until July, and observations are consistent with the few other records from the Red Sea. The number of Acropora species spawning was highest in April with 13 species spawning two nights before the full moon in 2011, 13 species spawning on the night of the full moon in 2012, and eight species spawning four nights after the full moon in 2013. The total number of species spawning was high in April, May, and June and involved 15–19 species per month in 2012. Only four species spawned in July 2012. Few regions worldwide have been similarly sampled and include the Philippines, Okinawa in Japan, and Palau, where spawning patterns are very similar to those in the central Red Sea and where corals spawn on nights around the full moon over a period of 3–4 months. In particular, in all four locations, Acropora are among the first species to spawn. Our results add to a growing body of evidence indicating that multi-species spawning synchrony is a feature of all speciose coral assemblages.

Identification of contrasting seasonal sea ice conditions during the Younger Dryas

Science.gov (United States)

Cabedo-Sanz, P.; Belt, S. T.; Knies, J.

2012-12-01

The presence of the sea ice diatom biomarker IP25 in Arctic marine sediments has been used in previous studies as a proxy for past spring sea ice occurrence and as an indicator of wider palaeoenvironmental conditions for different regions of the Arctic over various timescales [e.g. 1, 2]. The current study focuses on high-resolution palaeo sea ice reconstructions for northern Norway during the last ca. 15 cal. kyr BP. Within this study, particular emphasis has been placed on the identification of the sea ice conditions during the Younger Dryas and the application of different biomarker-based proxies to both identify and quantify seasonal sea ice conditions. Firstly, the appearance of the specific sea ice diatom proxy IP25 at ca. 12.9 cal. kyr BP in a marine sediment core (JM99-1200) obtained from Andfjorden has provided an unambiguous but qualitative measure of seasonal sea ice and thus the onset of the Younger Dryas stadial. The near continuous occurrence of IP25 for the next ca. 1400 yr demonstrates seasonal sea ice during this interval, although variable abundances suggest that the recurrent conditions in the early-mid Younger Dryas (ca. 12.9 - 11.9 cal. kyr BP) changed significantly from stable to highly variable sea ice conditions at ca. 11.9 cal. kyr BP and this instability in sea ice prevailed for the subsequent ca. 400 yr. At ca. 11.5 cal. kyr BP, IP25 disappeared from the record indicating ice-free conditions that signified the beginning of the Holocene. Similarly, a high resolution record from the Kveithola Through, western Barents Sea, showed clearly higher IP25 concentrations during the Younger Dryas stadial compared to the Holocene. For both marine records, the IP25 concentrations were also combined with those of the open water phytoplankton biomarker brassicasterol to generate PBIP25 data from which more quantitative measurements of sea ice were determined. The contrasting seasonal sea ice conditions during the Younger Dryas were further verified

Application and Network-Cognizant Proxies - Final Report

Energy Technology Data Exchange (ETDEWEB)

Antonio Ortega; Daniel C. Lee

2003-03-24

OAK B264 Application and Network-Cognizant Proxies - Final Report. Current networks show increasing heterogeneity both in terms of their bandwidths/delays and the applications they are required to support. This is a trend that is likely to intensify in the future, as real-time services, such as video, become more widely available and networking access over wireless links becomes more widespread. For this reason they propose that application-specific proxies, intermediate network nodes that broker the interactions between server and client, will become an increasingly important network element. These proxies will allow adaptation to changes in network characteristics without requiring a direct intervention of either server or client. Moreover, it will be possible to locate these proxies strategically at those points where a mismatch occurs between subdomains (for example, a proxy could be placed so as to act as a bridge between a reliable network domain and an unreliable one). This design philosophy favors scalability in the sense that the basic network infrastructure can remain unchanged while new functionality can be added to proxies, as required by the applications. While proxies can perform numerous generic functions, such as caching or security, they concentrate here on media-specific, and in particular video-specific, tasks. The goal of this project was to demonstrate that application- and network-specific knowledge at a proxy can improve overall performance especially under changing network conditions. They summarize below the work performed to address these issues. Particular effort was spent in studying caching techniques and on video classification to enable DiffServ delivery. other work included analysis of traffic characteristics, optimized media scheduling, coding techniques based on multiple description coding, and use of proxies to reduce computation costs. This work covered much of what was originally proposed but with a necessarily reduced scope.

Web proxy auto discovery for the WLCG

CERN Document Server

Dykstra, D; Blumenfeld, B; De Salvo, A; Dewhurst, A; Verguilov, V

2017-01-01

All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids regis...

Detecting instabilities in tree-ring proxy calibration

Directory of Open Access Journals (Sweden)

H. Visser

2010-06-01

Full Text Available Evidence has been found for reduced sensitivity of tree growth to temperature in a number of forests at high northern latitudes and alpine locations. Furthermore, at some of these sites, emergent subpopulations of trees show negative growth trends with rising temperature. These findings are typically referred to as the "Divergence Problem" (DP. Given the high relevance of paleoclimatic reconstructions for policy-related studies, it is important for dendrochronologists to address this issue of potential model uncertainties associated with the DP. Here we address this issue by proposing a calibration technique, termed "stochastic response function" (SRF, which allows the presence or absence of any instabilities in growth response of trees (or any other climate proxy to their calibration target to be visualized and detected. Since this framework estimates confidence limits and subsequently provides statistical significance tests, the approach is also very well suited for proxy screening prior to the generation of a climate-reconstruction network.

Two examples of tree growth/climate relationships are provided, one from the North American Arctic treeline and the other from the upper treeline in the European Alps. Instabilities were found to be present where stabilities were reported in the literature, and vice versa, stabilities were found where instabilities were reported. We advise to apply SRFs in future proxy-screening schemes, next to the use of correlations and RE/CE statistics. It will improve the strength of reconstruction hindcasts.

Quick, “Imputation-free” meta-analysis with proxy-SNPs

Directory of Open Access Journals (Sweden)

Meesters Christian

2012-09-01

Full Text Available Abstract Background Meta-analysis (MA is widely used to pool genome-wide association studies (GWASes in order to a increase the power to detect strong or weak genotype effects or b as a result verification method. As a consequence of differing SNP panels among genotyping chips, imputation is the method of choice within GWAS consortia to avoid losing too many SNPs in a MA. YAMAS (Yet Another Meta Analysis Software, however, enables cross-GWAS conclusions prior to finished and polished imputation runs, which eventually are time-consuming. Results Here we present a fast method to avoid forfeiting SNPs present in only a subset of studies, without relying on imputation. This is accomplished by using reference linkage disequilibrium data from 1,000 Genomes/HapMap projects to find proxy-SNPs together with in-phase alleles for SNPs missing in at least one study. MA is conducted by combining association effect estimates of a SNP and those of its proxy-SNPs. Our algorithm is implemented in the MA software YAMAS. Association results from GWAS analysis applications can be used as input files for MA, tremendously speeding up MA compared to the conventional imputation approach. We show that our proxy algorithm is well-powered and yields valuable ad hoc results, possibly providing an incentive for follow-up studies. We propose our method as a quick screening step prior to imputation-based MA, as well as an additional main approach for studies without available reference data matching the ethnicities of study participants. As a proof of principle, we analyzed six dbGaP Type II Diabetes GWAS and found that the proxy algorithm clearly outperforms naïve MA on the p-value level: for 17 out of 23 we observe an improvement on the p-value level by a factor of more than two, and a maximum improvement by a factor of 2127. Conclusions YAMAS is an efficient and fast meta-analysis program which offers various methods, including conventional MA as well as inserting proxy

Register of the last 1000 years of environmental, climatic and anthropogenic change in Isla Grande de Chiloé, inferred through a multi-proxy approach: Lake Pastahué, Chile-South Center (42°S)

Science.gov (United States)

Troncoso, Jose; Alvarez, Denisse; Díaz, Gustavo; Fierro, Pablo; Araneda, Alberto; Torrejón, Fernando; Rondanelli, Mauricio; Fagel, Nathalie; Urrutia, Roberto

2017-04-01

Knowledge of the past environmental and climatic conditions of the lake ecosystems of the Isla Grande de Chiloé and its relationship with the anthropic effect, on a high temporal resolution scale, is scarcely known. Specifically, multi-proxy studies provide a better understanding of the context in which changes occurred in the past. This insular region is particularly interesting because environmental conditions (pre and post-Hispanic) and knowledge about the impacts generated in the ecosystems during the Spanish colonization process have so far been little studied, compared to the rest of Chile continental. This research is a new contribution to the scarce information existing for the last millennium of the Isla Grande de Chiloé. The objective of this work was to reconstruct the environmental and climatic history of the last 1000 years, from the Lake Pastahué, in the Isla Grande de Chiloé through a multi-proxy analysis and compare them with other records for the region. The core sediment was sub-sampled to perform sedimentological analysis (organic matter, carbonates, magnetic susceptibility and granulometry) and biological indicators (pollen, chironomids). The age model was constructed from the activity of 210Pb,137Cs and 14C. The pollen results reveal a composition of nordpatagónico forest represented by Nothofagus, Weinmannia, Drimys, Tepualia, Myrtaceae, Poaceae and Pteridophyta, while the anthropic effect for the last cm of the profile is represented by Rumex and Pinus. The results show a significant increase in magnetic susceptibility since the middle of the 20th century, suggesting an increase in allochthonous material to the lake. The sedimentological parameters and the chironomid assembly show similar variations along the profile, which also shows changes in the trophic state of the lake. The changes recorded in lake Pastahue are directly related to past climatic phenomena occurring in the last millennium, such as the medieval climatic anomaly (MCA

87Sr/86Sr as a quantitative geochemical proxy for 14C reservoir age in dynamic, brackish waters: assessing applicability and quantifying uncertainties.

Science.gov (United States)

Lougheed, Bryan; van der Lubbe, Jeroen; Davies, Gareth

2016-04-01

Accurate geochronologies are crucial for reconstructing the sensitivity of brackish and estuarine environments to rapidly changing past external impacts. A common geochronological method used for such studies is radiocarbon (14C) dating, but its application in brackish environments is severely limited by an inability to quantify spatiotemporal variations in 14C reservoir age, or R(t), due to dynamic interplay between river runoff and marine water. Additionally, old carbon effects and species-specific behavioural processes also influence 14C ages. Using the world's largest brackish water body (the estuarine Baltic Sea) as a test-bed, combined with a comprehensive approach that objectively excludes both old carbon and species-specific effects, we demonstrate that it is possible to use 87Sr/86Sr ratios to quantify R(t) in ubiquitous mollusc shell material, leading to almost one order of magnitude increase in Baltic Sea 14C geochronological precision over the current state-of-the-art. We propose that this novel proxy method can be developed for other brackish water bodies worldwide, thereby improving geochronological control in these climate sensitive, near-coastal environments.

Multi-proxy experimental calibration in cold water corals for high resolution paleoreconstructions

Science.gov (United States)

Pelejero, C.; Martínez-Dios, A.; Ko, S.; Sherrell, R. M.; Kozdon, R.; López-Sanz, À.; Calvo, E.

2017-12-01

Cold-water corals (CWCs) display an almost cosmopolitan distribution over a wide range of depths. Similar to their tropical counterparts, they can provide continuous, high-resolution records of up to a century or more. Several CWC elemental and isotopic ratios have been suggested as useful proxies, but robust calibrations under controlled conditions in aquaria are needed. Whereas a few such calibrations have been performed for tropical corals, they are still pending for CWCs. This reflects the technical challenges involved in maintaining these slow-growing animals alive during the long-term experiments required to achieve sufficient skeletal growth for geochemical analyses. We will show details of the set up and initial stages of a long-term experiment being run at the ICM (Barcelona), where live specimens (>150) of Desmophyllum dianthus sampled in Comau Fjord (Chile) are kept under controlled and manipulated physical chemistry (temperature, pH, phosphate, barium, cadmium) and feeding conditions. With this set up, we aim to calibrate experimentally several specific elemental ratios including P/Ca, Ba/Ca, Cd/Ca, B/Ca, U/Ca and Mg/Li as proxies of nutrients dynamics, pH, carbonate ion concentration and temperature. For the trace element analysis, we are analyzing coral skeletons using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), running quantitative analyses on spot sizes of tens of microns, and comparing to micromilling and solution ICP-MS. Preliminary data obtained using these techniques will be presented, as well as measurements of calcification rate. Since coral-water corals are potentially vulnerable to ocean acidification, the same experiment is being exploited to assess potential effects of the pH stressor in D. dianthus; main findings to date will be summarized.

Tracking multidecadal trends in sea level using coral microatolls

Science.gov (United States)

Majewski, Jedrzej; Pham, Dat; Meltzner, Aron; Switzer, Adam; Horton, Benjamin; Heng, Shu Yun; Warrick, David

2015-04-01

Tracking multidecadal trends in sea level using coral microatolls Jędrzej M. Majewski 1, Dat T. Pham1, Aron J. Meltzner 1, Adam D. Switzer 1, Benjamin P. Horton2, Shu Yun Heng1, David Warrick3, 1 Earth Observatory of Singapore, Nanyang Technological University, Singapore 2 Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA 3 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA Coral microatolls can be used to study relative sea-level change at multidecadal timescales associated with vertical land movements, climate induced sea-level rise and other oceanographic phenomena such as the El Niño/Southern Oscillation (ENSO) or Indian Ocean Dipole (IOD) with the assumption that the highest level of survival (HLS) of coral microatolls track sea level over the course of their lifetimes. In this study we compare microatoll records covering from as early as 1883 through 2013, from two sites in Indonesia, with long records (>20 years) from proximal tide gauges, satellite altimetry, and other sea-level reconstructions. We compared the HLS time series derived from open-ocean and moated (or ponded) microatolls on tectonically stable Belitung Island and a potentially tectonically active setting in Mapur Island, with sea-level reconstructions for 1950-2011. The sea-level reconstructions are based on ground and satellite measurements, combining a tide model with the Estimating the Circulation and Climate of the Ocean (ECCO) model. Our results confirm that open-ocean microatolls do track low water levels at multi decadal time scales and can be used as a proxy for relative sea level (RSL) over time. However, microatolls that are even partially moated are unsuitable and do not track RSL; rather, their growth patterns likely reflect changes in the elevation of the sill of the local pond, as reported by earlier authors. Our ongoing efforts will include an attempt to recognize similarities in moated

Demonstration of SST value as EBVs descriptor in the Mediterranean Sea

Science.gov (United States)

Valentini, E.; Filipponi, F.; Nguyen Xuan, A.; Taramelli, A.

2017-12-01

Sea Surface Temperature is an Essential Climate and Ocean Variable (ECV - EOV) able to capture critical scales in the seascape warming patterns and to highlight the exceeding of thresholds. This presentation addresses the changes of the SST in the last three decades over the Mediterranean Sea, a "Large Marine Ecosystem (LME)", in order to speculate the value of such powerful variable, as proxy for the assessment of ecosystem state in terms of ecosystem structures, functions and composition key descriptor. Time series of daily SST for the period 1982-2016, estimated from multi-sensor satellite data and provided by Copernicus Marine Environment Monitoring Service (CMEMS-EU) are used to perform different statistical analysis on common fish species. Results highlight the critical conditions, the general trends as well as the spatial and temporal patterns, in terms of thermal growth, vitality and stress influence on selected fish species. Results confirm a constant increasing trend in SST with an average rise of 1.4° C in the past thirty years. The variance associated to the average trend is not constant across the entire Mediterranean Sea opening the way to multiple scenarios for fish growth and vitality in the diverse sub-basins. A major effort is oriented in addressing the cross-scale ecological interactions to assess the feasibility of using SST as descriptor for Essential Biodiversity Variables, able to prioritize areas and to feed operational tools for planning and management in the Mediterranean LME.

Paper Prototyping: The Surplus Merit of a Multi-Method Approach

Directory of Open Access Journals (Sweden)

Stephanie Bettina Linek

2015-07-01

Full Text Available This article describes a multi-method approach for usability testing. The approach combines paper prototyping and think-aloud with two supplemental methods: advanced scribbling and a handicraft task. The method of advanced scribbling instructs the participants to use different colors for marking important, unnecessary and confusing elements in a paper prototype. In the handicraft task the participants have to tinker a paper prototype of their wish version. Both methods deliver additional information on the needs and expectations of the potential users and provide helpful indicators for clarifying complex or contradictory findings. The multi-method approach and its surplus benefit are illustrated by a pilot study on the redesign of the homepage of a library 2.0. The findings provide positive evidence for the applicability of the advanced scribbling and the handicraft task as well as for the surplus merit of the multi-method approach. The article closes with a discussion and outlook. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs150379

Ontogenetic investigation of underwater hearing capabilities in loggerhead sea turtles (Caretta caretta) using a dual testing approach.

Science.gov (United States)

Lavender, Ashley L; Bartol, Soraya M; Bartol, Ian K

2014-07-15

Sea turtles reside in different acoustic environments with each life history stage and may have different hearing capacity throughout ontogeny. For this study, two independent yet complementary techniques for hearing assessment, i.e. behavioral and electrophysiological audiometry, were employed to (1) measure hearing in post-hatchling and juvenile loggerhead sea turtles Caretta caretta (19-62 cm straight carapace length) to determine whether these migratory turtles exhibit an ontogenetic shift in underwater auditory detection and (2) evaluate whether hearing frequency range and threshold sensitivity are consistent in behavioral and electrophysiological tests. Behavioral trials first required training turtles to respond to known frequencies, a multi-stage, time-intensive process, and then recording their behavior when they were presented with sound stimuli from an underwater speaker using a two-response forced-choice paradigm. Electrophysiological experiments involved submerging restrained, fully conscious turtles just below the air-water interface and recording auditory evoked potentials (AEPs) when sound stimuli were presented using an underwater speaker. No significant differences in behavior-derived auditory thresholds or AEP-derived auditory thresholds were detected between post-hatchling and juvenile sea turtles. While hearing frequency range (50-1000/1100 Hz) and highest sensitivity (100-400 Hz) were consistent in audiograms pooled by size class for both behavior and AEP experiments, both post-hatchlings and juveniles had significantly higher AEP-derived than behavior-derived auditory thresholds, indicating that behavioral assessment is a more sensitive testing approach. The results from this study suggest that post-hatchling and juvenile loggerhead sea turtles are low-frequency specialists, exhibiting little differences in threshold sensitivity and frequency bandwidth despite residence in acoustically distinct environments throughout ontogeny. © 2014

Multi-criteria multi-stakeholder decision analysis using a fuzzy-stochastic approach for hydrosystem management

Directory of Open Access Journals (Sweden)

Y. H. Subagadis

2014-09-01

Full Text Available The conventional methods used to solve multi-criteria multi-stakeholder problems are less strongly formulated, as they normally incorporate only homogeneous information at a time and suggest aggregating objectives of different decision-makers avoiding water–society interactions. In this contribution, Multi-Criteria Group Decision Analysis (MCGDA using a fuzzy-stochastic approach has been proposed to rank a set of alternatives in water management decisions incorporating heterogeneous information under uncertainty. The decision making framework takes hydrologically, environmentally, and socio-economically motivated conflicting objectives into consideration. The criteria related to the performance of the physical system are optimized using multi-criteria simulation-based optimization, and fuzzy linguistic quantifiers have been used to evaluate subjective criteria and to assess stakeholders' degree of optimism. The proposed methodology is applied to find effective and robust intervention strategies for the management of a coastal hydrosystem affected by saltwater intrusion due to excessive groundwater extraction for irrigated agriculture and municipal use. Preliminary results show that the MCGDA based on a fuzzy-stochastic approach gives useful support for robust decision-making and is sensitive to the decision makers' degree of optimism.

Patch-reef morphology as a proxy for Holocene sea-level variability, Northern Florida Keys, USA

Science.gov (United States)

Brock, J.C.; Palaseanu-Lovejoy, M.; Wright, C.W.; Nayegandhi, A.

2008-01-01

A portion of the northern Florida Keys reef tract was mapped with the NASA Experimental Advanced Airborne Research Lidar (EAARL) and the morphology of patch reefs was related to variations in Holocene sea level. Following creation of a lidar digital elevation model (DEM), geospatial analyses delineated morphologic attributes of 1,034 patch reefs (reef depth, basal area, height, volume, and topographic complexity). Morphometric analysis revealed two morphologically different populations of patch reefs associated with two distinct depth intervals above and below a water depth of 7.7 m. Compared to shallow reefs, the deep reefs were smaller in area and volume and showed no trend in topographic complexity relative to water depth. Shallow reefs were more variable in area and volume and became flatter and less topographically complex with decreasing water depth. The knoll-like morphology of deep reefs was interpreted as consistent with steady and relatively rapidly rising early Holocene sea level that restricted the lateral growth of reefs. The morphology of shallow 'pancake-shaped' reefs at the highest platform elevations was interpreted as consistent with fluctuating sea level during the late Holocene. Although the ultimate cause for the morphometric depth trends remains open to interpretation, these interpretations are compatible with a recent eustatic sea-level curve that hindcasts fluctuating late Holocene sea level. Thus it is suggested that the morphologic differences represent two stages of reef accretion that occurred during different sea-level conditions. ?? 2008 Springer-Verlag.

Towards the best approach for wind wave modelling in the Red Sea

KAUST Repository

Langodan, Sabique

2015-04-01

While wind and wave modelling is nowadays quite satisfactory in the open oceans, problems are still present in the enclosed seas. In general, the smaller the basin, the poorer the models perform, especially if the basin is surrounded by a complex orography. The Red Sea is an extreme example in this respect, especially because of its long and narrow shape. This deceivingly simple domain offers very interesting challenges for wind and wave modeling, not easily, if ever, found elsewhere. Depending on the season, opposite wind regimes, one directed to southeast, the other one to northwest, are present and may coexist in the most northerly and southerly parts of the Red Sea. Where the two regimes meet, the wave spectra can be rather complicated and, crucially dependent on small details of the driving wind fields. We explored how well we could reproduce the general and unusual wind and wave patterns of the Red Sea using different meteorological products. Best results were obtained using two rather opposite approaches: the high-resolution Weather Research Forecasting (WRF) regional model and the slightly enhanced surface winds from the global European Centre for Medium-Range Weather Forecasts (ECMWF) model. We discuss the reasons why these two approaches produce the best results and the implications on wave modeling in the Red Sea. The unusual wind and wave patterns in the Red Sea suggest that the currently available wave model source functions may not properly represent the evolution of local fields. However, within limits, the WAVEWATCH III wave model, based on Janssen\\'s and also Ardhuin\\'s wave model physics, provides in many cases very reasonable results. Because surface winds lead to important uncertainties in wave simulation, we also discuss the impact of data assimilation for simulating the most accurate winds, and consequently waves, over the Red Sea.

River Export of Plastic from Land to Sea: A Global Modeling Approach

Science.gov (United States)

Siegfried, Max; Gabbert, Silke; Koelmans, Albert A.; Kroeze, Carolien; Löhr, Ansje; Verburg, Charlotte

2016-04-01

Plastic is increasingly considered a serious cause of water pollution. It is a threat to aquatic ecosystems, including rivers, coastal waters and oceans. Rivers transport considerable amounts of plastic from land to sea. The quantity and its main sources, however, are not well known. Assessing the amount of macro- and microplastic transport from river to sea is, therefore, important for understanding the dimension and the patterns of plastic pollution of aquatic ecosystems. In addition, it is crucial for assessing short- and long-term impacts caused by plastic pollution. Here we present a global modelling approach to quantify river export of plastic from land to sea. Our approach accounts for different types of plastic, including both macro- and micro-plastics. Moreover, we distinguish point sources and diffuse sources of plastic in rivers. Our modelling approach is inspired by global nutrient models, which include more than 6000 river basins. In this paper, we will present our modelling approach, as well as first model results for micro-plastic pollution in European rivers. Important sources of micro-plastics include personal care products, laundry, household dust and car tyre wear. We combine information on these sources with information on sewage management, and plastic retention during river transport for the largest European rivers. Our modelling approach may help to better understand and prevent water pollution by plastic , and at the same time serves as 'proof of concept' for future application on global scale.

Fuzzy Multi-objective Linear Programming Approach

Directory of Open Access Journals (Sweden)

Amna Rehmat

2007-07-01

Full Text Available Traveling salesman problem (TSP is one of the challenging real-life problems, attracting researchers of many fields including Artificial Intelligence, Operations Research, and Algorithm Design and Analysis. The problem has been well studied till now under different headings and has been solved with different approaches including genetic algorithms and linear programming. Conventional linear programming is designed to deal with crisp parameters, but information about real life systems is often available in the form of vague descriptions. Fuzzy methods are designed to handle vague terms, and are most suited to finding optimal solutions to problems with vague parameters. Fuzzy multi-objective linear programming, an amalgamation of fuzzy logic and multi-objective linear programming, deals with flexible aspiration levels or goals and fuzzy constraints with acceptable deviations. In this paper, a methodology, for solving a TSP with imprecise parameters, is deployed using fuzzy multi-objective linear programming. An example of TSP with multiple objectives and vague parameters is discussed.

OBJECT-ORIENTED CHANGE DETECTION BASED ON MULTI-SCALE APPROACH

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Y. Jia

2016-06-01

Full Text Available The change detection of remote sensing images means analysing the change information quantitatively and recognizing the change types of the surface coverage data in different time phases. With the appearance of high resolution remote sensing image, object-oriented change detection method arises at this historic moment. In this paper, we research multi-scale approach for high resolution images, which includes multi-scale segmentation, multi-scale feature selection and multi-scale classification. Experimental results show that this method has a stronger advantage than the traditional single-scale method of high resolution remote sensing image change detection.

350 Year Cloud Reconstruction Deduced from Northeast Caribbean Coral Proxies

Science.gov (United States)

Winter, A.; Sammarco, P. W.; Mikolajewicz, U.; Jury, M.; Zanchettin, D.

2014-12-01

Clouds are a major factor influencing the global climate and its response to external forcing through their implications for the global hydrological cycle, and hence for the planetary radiative budget. Clouds also contribute to regional climates and their variability through, e.g., the changes they induce in regional precipitation patterns. There have been very few studies of decadal and longer-term changes in cloud cover in the tropics and sub-tropics, both over land and the ocean. In the tropics, there is great uncertainty regarding how global warming will affect cloud cover. Observational satellite data are too short to unambiguously discern any temporal trends in cloud cover. Corals generally live in well-mixed coastal regions and can often record environmental conditions of large areas of the upper ocean. This is particularly the case at low latitudes. Scleractinian corals are sessile, epibenthic fauna, and the type of environmental information recorded at the location where the coral has been living is dependent upon the species of coral considered and proxy index of interest. Skeletons of scleractinian corals are considered to provide among the best records of high-resolution (sub-annual) environmental variability in the tropical and sub-tropical oceans. Zooxanthellate hermatypic corals in tropical and sub-tropical seas precipitate CaCO3 skeletons as they grow. This growth is made possible through the manufacture of CaCO3crystals, facilitated by the zooxanthellae. During the process of crystallization, the holobiont binds carbon of different isotopes into the crystals. Stable carbon isotope concentrations vary with a variety of environmental conditions. In the Caribbean, d13C in corals of the species Montastraea faveolata can be used as a proxy for changes in cloud cover. In this contribution, we will demonstrate that the stable isotope 13C varies concomitantly with cloud cover for the northeastern Caribbean region. Using this proxy we have been able to

Opportunities and limitations related to the application of plant-derived lipid molecular proxies in soil science

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B. Jansen

2017-11-01

Full Text Available The application of lipids in soils as molecular proxies, also often referred to as biomarkers, has dramatically increased in the last decades. Applications range from inferring changes in past vegetation composition, climate, and/or human presence to unraveling the input and turnover of soil organic matter (SOM. The molecules used are extractable and non-extractable lipids, including ester-bound lipids. In addition, the carbon or hydrogen isotopic composition of such molecules is used. While holding great promise, the application of soil lipids as molecular proxies comes with several constraining factors, the most important of which are (i variability in the molecular composition of plant-derived organic matter both internally and between individual plants, (ii variability in (the relative contribution of input pathways into the soil, and (iii the transformation and/or (selective degradation of (some of the molecules once present in the soil. Unfortunately, the information about such constraining factors and their impact on the applicability of molecular proxies is fragmented and scattered. The purpose of this study is to provide a critical review of the current state of knowledge with respect to the applicability of molecular proxies in soil science, specifically focusing on the factors constraining such applicability. Variability in genetic, ontogenetic, and environmental factors influences plant n-alkane patterns in such a way that no unique compounds or specific molecular proxies pointing to, for example, plant community differences or environmental influences, exist. Other components, such as n-alcohols, n-fatty acids, and cutin- and suberin-derived monomers, have received far less attention in this respect. Furthermore, there is a high diversity of input pathways offering both opportunities and limitations for the use of molecular proxies at the same time. New modeling approaches might offer a possibility to unravel such mixed input

A wind proxy based on migrating dunes at the Baltic coast: statistical analysis of the link between wind conditions and sand movement

Science.gov (United States)

Bierstedt, Svenja E.; Hünicke, Birgit; Zorita, Eduardo; Ludwig, Juliane

2017-07-01

We statistically analyse the relationship between the structure of migrating dunes in the southern Baltic and the driving wind conditions over the past 26 years, with the long-term aim of using migrating dunes as a proxy for past wind conditions at an interannual resolution. The present analysis is based on the dune record derived from geo-radar measurements by Ludwig et al. (2017). The dune system is located at the Baltic Sea coast of Poland and is migrating from west to east along the coast. The dunes present layers with different thicknesses that can be assigned to absolute dates at interannual timescales and put in relation to seasonal wind conditions. To statistically analyse this record and calibrate it as a wind proxy, we used a gridded regional meteorological reanalysis data set (coastDat2) covering recent decades. The identified link between the dune annual layers and wind conditions was additionally supported by the co-variability between dune layers and observed sea level variations in the southern Baltic Sea. We include precipitation and temperature into our analysis, in addition to wind, to learn more about the dependency between these three atmospheric factors and their common influence on the dune system. We set up a statistical linear model based on the correlation between the frequency of days with specific wind conditions in a given season and dune migration velocities derived for that season. To some extent, the dune records can be seen as analogous to tree-ring width records, and hence we use a proxy validation method usually applied in dendrochronology, cross-validation with the leave-one-out method, when the observational record is short. The revealed correlations between the wind record from the reanalysis and the wind record derived from the dune structure is in the range between 0.28 and 0.63, yielding similar statistical validation skill as dendroclimatological records.

Multi-scale dynamical analysis (MSDA) of sea level records versus PDO, AMO, and NAO indexes

OpenAIRE

Scafetta, Nicola

2013-01-01

Herein I propose a multi-scale dynamical analysis to facilitate the physical interpretation of tide gauge records. The technique uses graphical diagrams. It is applied to six secular-long tide gauge records representative of the world oceans: Sydney, Pacific coast of Australia; Fremantle, Indian Ocean coast of Australia; New York City, Atlantic coast of USA; Honolulu, U.S. state of Hawaii; San Diego, U.S. state of California; and Venice, Mediterranean Sea, Italy. For comparison, an equivalent...

Multi-model approach to characterize human handwriting motion.

Science.gov (United States)

Chihi, I; Abdelkrim, A; Benrejeb, M

2016-02-01

This paper deals with characterization and modelling of human handwriting motion from two forearm muscle activity signals, called electromyography signals (EMG). In this work, an experimental approach was used to record the coordinates of a pen tip moving on the (x, y) plane and EMG signals during the handwriting act. The main purpose is to design a new mathematical model which characterizes this biological process. Based on a multi-model approach, this system was originally developed to generate letters and geometric forms written by different writers. A Recursive Least Squares algorithm is used to estimate the parameters of each sub-model of the multi-model basis. Simulations show good agreement between predicted results and the recorded data.

An Assessment of the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

Science.gov (United States)

Steen, Laura E.; Ide, Robert F.; Van Zante, Judith F.

2015-01-01

The NASA Glenn Icing Research tunnel has been using an Icing Blade technique to measure cloud liquid water content (LWC) since 1980. The IRT conducted tests with SEA Multi-Element sensors from 2009 to 2011 to assess their performance in measuring LWC. These tests revealed that the Multi-Element sensors showed some significant advantages over the Icing Blade, particularly at higher water contents, higher impingement rates, and large drop sizes. Results of these and other tests are presented here.

Development of six PROMIS pediatrics proxy-report item banks.

Science.gov (United States)

Irwin, Debra E; Gross, Heather E; Stucky, Brian D; Thissen, David; DeWitt, Esi Morgan; Lai, Jin Shei; Amtmann, Dagmar; Khastou, Leyla; Varni, James W; DeWalt, Darren A

2012-02-22

Pediatric self-report should be considered the standard for measuring patient reported outcomes (PRO) among children. However, circumstances exist when the child is too young, cognitively impaired, or too ill to complete a PRO instrument and a proxy-report is needed. This paper describes the development process including the proxy cognitive interviews and large-field-test survey methods and sample characteristics employed to produce item parameters for the Patient Reported Outcomes Measurement Information System (PROMIS) pediatric proxy-report item banks. The PROMIS pediatric self-report items were converted into proxy-report items before undergoing cognitive interviews. These items covered six domains (physical function, emotional distress, social peer relationships, fatigue, pain interference, and asthma impact). Caregivers (n = 25) of children ages of 5 and 17 years provided qualitative feedback on proxy-report items to assess any major issues with these items. From May 2008 to March 2009, the large-scale survey enrolled children ages 8-17 years to complete the self-report version and caregivers to complete the proxy-report version of the survey (n = 1548 dyads). Caregivers of children ages 5 to 7 years completed the proxy report survey (n = 432). In addition, caregivers completed other proxy instruments, PedsQL™ 4.0 Generic Core Scales Parent Proxy-Report version, PedsQL™ Asthma Module Parent Proxy-Report version, and KIDSCREEN Parent-Proxy-52. Item content was well understood by proxies and did not require item revisions but some proxies clearly noted that determining an answer on behalf of their child was difficult for some items. Dyads and caregivers of children ages 5-17 years old were enrolled in the large-scale testing. The majority were female (85%), married (70%), Caucasian (64%) and had at least a high school education (94%). Approximately 50% had children with a chronic health condition, primarily asthma, which was diagnosed or treated within 6

Multidecadal variations in the early Holocene outflow of Red Sea Water into the Arabian Sea

Science.gov (United States)

Jung, S. J. A.; Ganssen, G. M.; Davies, G. R.

2001-12-01

We present Holocene stable oxygen isotope data from the deep Arabian Sea off Somalia at a decadal time resolution as a proxy for the history of intermediate/upper deep water. These data show an overall δ18O reduction by 0.5‰ between 10 and ˜6.5 kyr B.P. superimposed upon short-term δ18O variations at a decadal-centennial timescale. The amplitude of the decadal variations is 0.3‰ prior, and up to 0.6‰ subsequent, to ˜8.1 kyr B.P. We conclude from modeling experiments that the short-term δ18O variations between 10 and ˜6.5 kyr B.P. most likely document changes in the evaporation-precipitation balance in the central Red Sea. Changes in water temperature and salinity cause the outflowing Red Sea Water to settle roughly 800 m deeper than today.

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures

NARCIS (Netherlands)

Douglas, P.M.J.; Affek, H.P.; Ivany, L.C.; Houben, A.J.P.; Sijp, W.P.; Sluijs, A.; Schouten, S.; Pagani, M.

2014-01-01

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at

Controls on Arctic sea ice from first-year and multi-year ice survival rates

Science.gov (United States)

Armour, K.; Bitz, C. M.; Hunke, E. C.; Thompson, L.

2009-12-01

The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi-year (MY) ice. The transition to an Arctic that is populated by thinner first-year (FY) sea ice has important implications for future trends in area and volume. We develop a reduced model for Arctic sea ice with which we investigate how the survivability of FY and MY ice control various aspects of the sea-ice system. We demonstrate that Arctic sea-ice area and volume behave approximately as first-order autoregressive processes, which allows for a simple interpretation of September sea-ice in which its mean state, variability, and sensitivity to climate forcing can be described naturally in terms of the average survival rates of FY and MY ice. This model, used in concert with a sea-ice simulation that traces FY and MY ice areas to estimate the survival rates, reveals that small trends in the ice survival rates explain the decline in total Arctic ice area, and the relatively larger loss of MY ice area, over the period 1979-2006. Additionally, our model allows for a calculation of the persistence time scales of September area and volume anomalies. A relatively short memory time scale for ice area (~ 1 year) implies that Arctic ice area is nearly in equilibrium with long-term climate forcing at all times, and therefore observed trends in area are a clear indication of a changing climate. A longer memory time scale for ice volume (~ 5 years) suggests that volume can be out of equilibrium with climate forcing for long periods of time, and therefore trends in ice volume are difficult to distinguish from its natural variability. With our reduced model, we demonstrate the connection between memory time scale and sensitivity to climate forcing, and discuss the implications that a changing memory time scale has on the trajectory of ice area and volume in a warming climate. Our findings indicate that it is unlikely that a “tipping point” in September ice area and volume will be

Gravity-Driven Deposits in an Active Margin (Ionian Sea) Over the Last 330,000 Years

Science.gov (United States)

Köng, Eléonore; Zaragosi, Sébastien; Schneider, Jean-Luc; Garlan, Thierry; Bachèlery, Patrick; Sabine, Marjolaine; San Pedro, Laurine

2017-11-01

In the Ionian Sea, the subduction of the Nubia plate underneath the Eurasia plate leads to an important sediment remobilization on the Calabrian Arc and the Mediterranean Ridge. These events are often associated with earthquakes and tsunamis. In this study, we analyze gravity-driven deposits in order to establish their recurrence time on the Calabrian Arc and the western Mediterranean Ridge. Four gravity cores collected on ridges and slope basins of accretionary prisms record turbidites, megaturbidites, slumping and micro-faults over the last 330,000 years. These turbidites were dated by correlation with a hemipelagic core with a multi-proxy approach: radiometric dating, δ18O, b* colour curve, sapropels and tephrochronology. The origin of the gravity-driven deposits was studied with a sedimentary approach: grain-size, lithology, thin section, geochemistry of volcanic glass. The results suggest three periods of presence/absence of gravity-driven deposits: a first on the western lobe of the Calabrian Arc between 330,000 and 250,000 years, a second between 120,000 years and present day on the eastern lobe of the Calabrian Arc and over the last 60,000 years on the western lobe, and a third on the Mediterranean Ridge over the last 37,000 years. Return times for gravity-driven deposits are around 1,000 years during the most important record periods. The turbidite activity also highlights the presence of volcaniclastic turbidites that seems to be link to the Etna changing morphology over the last 320,000 years.

The role of proxy information in missing data analysis.

Science.gov (United States)

Huang, Rong; Liang, Yuanyuan; Carrière, K C

2005-10-01

This article investigates the role of proxy data in dealing with the common problem of missing data in clinical trials using repeated measures designs. In an effort to avoid the missing data situation, some proxy information can be gathered. The question is how to treat proxy information, that is, is it always better to utilize proxy information when there are missing data? A model for repeated measures data with missing values is considered and a strategy for utilizing proxy information is developed. Then, simulations are used to compare the power of a test using proxy to simply utilizing all available data. It is concluded that using proxy information can be a useful alternative when such information is available. The implications for various clinical designs are also considered and a data collection strategy for efficiently estimating parameters is suggested.

Transparent Proxy for Secure E-Mail

Science.gov (United States)

Michalák, Juraj; Hudec, Ladislav

2010-05-01

The paper deals with the security of e-mail messages and e-mail server implementation by means of a transparent SMTP proxy. The security features include encryption and signing of transported messages. The goal is to design and implement a software proxy for secure e-mail including its monitoring, administration, encryption and signing keys administration. In particular, we focus on automatic public key on-the-fly encryption and signing of e-mail messages according to S/MIME standard by means of an embedded computer system whose function can be briefly described as a brouter with transparent SMTP proxy.

Peat humification and climate change: a multi-site comparison from mires in south-east Alaska

Directory of Open Access Journals (Sweden)

R.J. Payne

2008-11-01

Full Text Available Peatland records of Holocene palaeoclimate have been widely used in Europe. Their potential in western North America remains largely unexploited despite an abundance of candidate sites. Peat humification analysis is a widely used technique for palaeoclimatic inference from peatlands. This study attempts to demonstrate a climatic role in determining peat humification by comparing low-resolution peat humification records from five mires in south-east Alaska. Humification was determined by alkali extraction and colorimetry and records dated by radiocarbon and tephrochronology. Testate amoebae analysis was carried out across a major humification-inferred wet shift in three of the sites. The humification results show variability down the length of the cores but there is only limited agreement between records from different sites. Many general trends in the data appear to be out of phase and periods of proxy 'complacency' are shown. This study does not provide strong evidence for climatic forcing of humification in these sites. Methodological issues including possible problems with the age-depth models and the role of a peat-forming plant species signal in the humification data are discussed. The results support previous studies in suggesting the value of employing a multi-proxy, multi-site, and possibly multi-core approach in peat-based palaeoclimatology.

SeaSketch: Implementation of a Decision-Support Platform for a Channel Islands National Marine Sanctuary Multi-sector Working Group

Science.gov (United States)

Goldberg, G.; McClintock, W.

2016-12-01

Effective interagency and cross-sector coordination is essential to ecosystem based management which depends on processes characterized by collaboration and science-based information. Many technological barriers that exist in the development of science-based management plans are closely tied to process challenges, such as the sharing of data and information or the inclusion of parties with varied levels of technical experience. The Channel Islands National Marine Sanctuary has convened a diverse working group to develop recommendations for the management of marine shipping in and around the Santa Barbara Channel, as well as recommendations regarding research needs and outreach strategies. Working group members take a multi-issue approach with four distinct goals related to the reduction of ship strikes on whales, emissions and air quality, conflicting ocean uses, and issues of navigational safety. Members range from industry representatives, scientists, and multiple local and federal government entities. The recommended management plans will be based in the best-available science, and will build off of previous efforts, making this an interesting case study of adaptive management. In addition to support from the Sanctuary and professional facilitators, the group is using a decision-support platform, SeaSketch (safepassage.seasketch.org). SeaSketch is a web-based GIS that supports collaborative science-based marine spatial planning (MSP). Each feature supports a step of the MSP process, from data gathering, identification of data needs, the design of spatial plans, evaluation of those plans with analytics, and map-based forums that facilitate data-driven discussions. Working group members are able to access these tools to explore management options and collaborate remotely, in addition to using the platform during in-person meetings and webinars. Empowering diverse audiences to engage in the design of science-based plans is of key importance to developing ecosystem

A multi-model ensemble approach to seabed mapping

Science.gov (United States)

Diesing, Markus; Stephens, David

2015-06-01

Seabed habitat mapping based on swath acoustic data and ground-truth samples is an emergent and active marine science discipline. Significant progress could be achieved by transferring techniques and approaches that have been successfully developed and employed in such fields as terrestrial land cover mapping. One such promising approach is the multiple classifier system, which aims at improving classification performance by combining the outputs of several classifiers. Here we present results of a multi-model ensemble applied to multibeam acoustic data covering more than 5000 km2 of seabed in the North Sea with the aim to derive accurate spatial predictions of seabed substrate. A suite of six machine learning classifiers (k-Nearest Neighbour, Support Vector Machine, Classification Tree, Random Forest, Neural Network and Naïve Bayes) was trained with ground-truth sample data classified into seabed substrate classes and their prediction accuracy was assessed with an independent set of samples. The three and five best performing models were combined to classifier ensembles. Both ensembles led to increased prediction accuracy as compared to the best performing single classifier. The improvements were however not statistically significant at the 5% level. Although the three-model ensemble did not perform significantly better than its individual component models, we noticed that the five-model ensemble did perform significantly better than three of the five component models. A classifier ensemble might therefore be an effective strategy to improve classification performance. Another advantage is the fact that the agreement in predicted substrate class between the individual models of the ensemble could be used as a measure of confidence. We propose a simple and spatially explicit measure of confidence that is based on model agreement and prediction accuracy.

Generating multi-double-scroll attractors via nonautonomous approach.

Science.gov (United States)

Hong, Qinghui; Xie, Qingguo; Shen, Yi; Wang, Xiaoping

2016-08-01

It is a common phenomenon that multi-scroll attractors are realized by introducing the various nonlinear functions with multiple breakpoints in double scroll chaotic systems. Differently, we present a nonautonomous approach for generating multi-double-scroll attractors (MDSA) without changing the original nonlinear functions. By using the multi-level-logic pulse excitation technique in double scroll chaotic systems, MDSA can be generated. A Chua's circuit, a Jerk circuit, and a modified Lorenz system are given as designed example and the Matlab simulation results are presented. Furthermore, the corresponding realization circuits are designed. The Pspice results are in agreement with numerical simulation results, which verify the availability and feasibility of this method.

Interconnected levels of Multi-Stage Marketing – A Triadic approach

DEFF Research Database (Denmark)

Vedel, Mette; Geersbro, Jens; Ritter, Thomas

2012-01-01

must not only decide in general on the merits of multi-stage marketing for their firm, but must also decide on which level they will engage in multi-stage marketing. The triadic perspective enables a rich and multi-dimensional understanding of how different business relationships influence each other......Multi-stage marketing gains increasing attention as knowledge of and influence on the customer's customer become more critical for the firm's success. Despite this increasing managerial relevance, systematic approaches for analyzing multi-stage marketing are still missing. This paper conceptualizes...... different levels of multi-stage marketing and illustrates these stages with a case study. In addition, a triadic perspective is introduced as an analytical tool for multi-stage marketing research. The results from the case study indicate that multi-stage marketing exists on different levels. Thus, managers...

Past climate variability between 97 and 7 ka reconstructed from a multi proxy speleothem record from Western Cuba

Science.gov (United States)

Winterhalder, Sophie; Scholz, Denis; Mangini, Augusto; Spötl, Christoph; Jochum, Klaus Peter; Pajón, Jesús M.

2016-04-01

The tropical hydrological cycle plays a key role in regulating global climate, mainly through the export of heat and moisture to higher latitudes, and is highly sensitive to climate change, for instance due to changes in the position of the Intertropical Convergence Zone (ITCZ). Previous work on Caribbean stalagmites suggests a strong connection of precipitation variability to North Atlantic (NA) sea surface temperatures on multidecadal to millenial timescales (Fensterer et al., 2012; Fensterer et al., 2013; Winter et al., 2011). Cold phases in the NA potentially lead to a southward shift of the ITCZ and thus drier conditions in Cuba. On orbital timescales, Cuban stalagmites suggest a relation of speleothem δ18O values with the δ18O value of Caribbean surface waters (Fensterer et al., 2013). Here we present an expansion of the Cuban speleothem record covering the whole last glacial period from the end of MIS5c (97 ka BP) until 7 ka with hiatuses between 93-80 ka, 37-35 ka and 13-10 ka. Stalagmite Cuba medio (CM) has been precisely dated with 60 230Th/U-ages, mainly performed by the MC-ICPMS technique. The δ18O and δ13C records are completed by a continuous, high resolution LA-ICPMS trace element profile. These data allow for the first time to establish a multi-proxy climate reconstruction for the North Western Caribbean at decadal to centennial resolution for this period. The long-term variability of the δ18O values probably reflects rainfall amount in Cuba. The response to some Dansgaard/Oeschger and Heinrich stadials confirms the previously observed correlation between Caribbean and NA climate variability. However, this connection is not clearly imprinted throughout the record. Furthermore, trace elements, such as Mg, do not proof without ambiguity drier conditions in Cuba during NA cold events, such as the Heinrich stadials. This suggests that climate variability in Cuba was more complex during the last 100ka, and that the NA was not the only driving factor

Development of six PROMIS pediatrics proxy-report item banks

Directory of Open Access Journals (Sweden)

Irwin Debra E

2012-02-01

Full Text Available Abstract Background Pediatric self-report should be considered the standard for measuring patient reported outcomes (PRO among children. However, circumstances exist when the child is too young, cognitively impaired, or too ill to complete a PRO instrument and a proxy-report is needed. This paper describes the development process including the proxy cognitive interviews and large-field-test survey methods and sample characteristics employed to produce item parameters for the Patient Reported Outcomes Measurement Information System (PROMIS pediatric proxy-report item banks. Methods The PROMIS pediatric self-report items were converted into proxy-report items before undergoing cognitive interviews. These items covered six domains (physical function, emotional distress, social peer relationships, fatigue, pain interference, and asthma impact. Caregivers (n = 25 of children ages of 5 and 17 years provided qualitative feedback on proxy-report items to assess any major issues with these items. From May 2008 to March 2009, the large-scale survey enrolled children ages 8-17 years to complete the self-report version and caregivers to complete the proxy-report version of the survey (n = 1548 dyads. Caregivers of children ages 5 to 7 years completed the proxy report survey (n = 432. In addition, caregivers completed other proxy instruments, PedsQL™ 4.0 Generic Core Scales Parent Proxy-Report version, PedsQL™ Asthma Module Parent Proxy-Report version, and KIDSCREEN Parent-Proxy-52. Results Item content was well understood by proxies and did not require item revisions but some proxies clearly noted that determining an answer on behalf of their child was difficult for some items. Dyads and caregivers of children ages 5-17 years old were enrolled in the large-scale testing. The majority were female (85%, married (70%, Caucasian (64% and had at least a high school education (94%. Approximately 50% had children with a chronic health condition, primarily

How Vulnerable is Perennial Sea Ice? Insights from Earth's Late Cenozoic Natural Experiments (Invited)

Science.gov (United States)

Brigham-Grette, J.; Polyak, L. V.; Caissie, B.; Sharko, C. J.; Petsch, S.

2010-12-01

Sea ice is an important component of the climate system. Yet, reconstructions of Arctic sea ice conditions reflecting glacial and interglacial change over the past 3 million years are almost nonexistent. Our work to evaluate the sea ice and sea surface temperature record of the Bering Strait region builds on a review of the sea ice history of the pan-Arctic. The best estimates of sea ice make use of indirect proxies based on reconstructions of treeline, sea surface temperatures, depositional systems, and the ecological preferences of extant marine microfossil species. The development of new proxies of past sea ice extent including microfossil assemblages (diatoms, ostracodes) and biomarker proxies (IP25) show promise for quantifying seasonal concentrations of sea ice cover on centennial to millennial timescales. Using both marine and terrestrial information, periods of restricted sea ice and ice-free Arctic conditions can be inferred for parts of the late Cenozoic. The Arctic Ocean borderlands contain clear stratigraphic evidence for forested conditions at intervals over the past 50 million years, recording the migration of treeline from High Arctic coastal locations within the Canadian Archipelago. Metasequoia forests of the peak Eocene gave way to a variety of biomass-rich circumarctic redwood forests by 46 Ma. Between 23 and 16 Ma, cool-temperate metasequoia forests dominated NE Alaska and the Yukon while mixed conifer-hardwood forests (similar to those of modern southern maritime Canada and New England) dominated the central Canadian Archipelago. By 16 Ma, these forests gave way to larch and spruce. From 5 to 3 Ma the braid plains of the Beaufort Fm were dominated by over 100 vascular plants including pine and birch, while other locations remained dominated by spruce and larch. Boreal conditions across northern Greenland and arctic Alaska are consistent with the presence of bivalve Arctica islandica in marine sediments capping the Beaufort Formation on Meighen

The effects of additional black carbon on the albedo of Arctic sea ice: variation with sea ice type and snow cover

Directory of Open Access Journals (Sweden)

A. A. Marks

2013-07-01

Full Text Available The response of the albedo of bare sea ice and snow-covered sea ice to the addition of black carbon is calculated. Visible light absorption and light-scattering cross-sections are derived for a typical first-year and multi-year sea ice with both "dry" and "wet" snow types. The cross-sections are derived using data from a 1970s field study that recorded both reflectivity and light penetration in Arctic sea ice and snow overlying sea ice. The variation of absorption cross-section over the visible wavelengths suggests black carbon is the dominating light-absorbing impurity. The response of first-year and multi-year sea ice albedo to increasing black carbon, from 1 to 1024 ng g−1, in a top 5 cm layer of a 155 cm-thick sea ice was calculated using a radiative-transfer model. The albedo of the first-year sea ice is more sensitive to additional loadings of black carbon than the multi-year sea ice. An addition of 8 ng g−1 of black carbon causes a decrease to 98.7% of the original albedo for first-year sea ice compared to a decrease to 99.7% for the albedo of multi-year sea ice, at a wavelength of 500 nm. The albedo of sea ice is surprisingly unresponsive to additional black carbon up to 100 ng g−1 . Snow layers on sea ice may mitigate the effects of black carbon in sea ice. Wet and dry snow layers of 0.5, 1, 2, 5 and 10 cm depth were added onto the sea ice surface. The albedo of the snow surface was calculated whilst the black carbon in the underlying sea ice was increased. A layer of snow 0.5 cm thick greatly diminishes the effect of black carbon in sea ice on the surface albedo. The albedo of a 2–5 cm snow layer (less than the e-folding depth of snow is still influenced by the underlying sea ice, but the effect of additional black carbon in the sea ice is masked.

Secure Mobile Agent from Leakage-Resilient Proxy Signatures

Directory of Open Access Journals (Sweden)

Fei Tang

2015-01-01

Full Text Available A mobile agent can sign a message in a remote server on behalf of a customer without exposing its secret key; it can be used not only to search for special products or services, but also to make a contract with a remote server. Hence a mobile agent system can be used for electronic commerce as an important key technology. In order to realize such a system, Lee et al. showed that a secure mobile agent can be constructed using proxy signatures. Intuitively, a proxy signature permits an entity (delegator to delegate its signing right to another entity (proxy to sign some specified messages on behalf of the delegator. However, the proxy signatures are often used in scenarios where the signing is done in an insecure environment, for example, the remote server of a mobile agent system. In such setting, an adversary could launch side-channel attacks to exploit some leakage information about the proxy key or even other secret states. The proxy signatures which are secure in the traditional security models obviously cannot provide such security. Based on this consideration, in this paper, we design a leakage-resilient proxy signature scheme for the secure mobile agent systems.

Multi-proxy paleoenvironmental reconstruction of saline lake carbonates: Paleoclimatic and paleogeographic implications (Priabonian-Rupelian, Issirac Basin, SE France)

Science.gov (United States)

Lettéron, Alexandre; Fournier, François; Hamon, Youri; Villier, Loïc; Margerel, Jean-Pierre; Bouche, Alexandre; Feist, Monique; Joseph, Philippe

2017-08-01

A 200-m thick carbonate succession has been deposited in shallow-water, saline lake environments during the Priabonian-Rupelian in the Issirac Basin (South-East France). The palaeoenvironmental and palaeogeographic significance of such saline lake carbonates has been characterized on the basis of a multi-proxy analysis including 1) depositional and diagenetic features, 2) biological components (molluscs, ostracods, benthic foraminifers, characean) and 3) carbon, oxygen and strontium stable isotopes. Biological associations are indicative of dominantly shallow (climate (dry versus humid) are the three key factors controlling the water composition, carbonate production and depositional environments in the Issirac lake. Although the ASCI (Alès-Issirac-Saint-Chaptes) lacustrine system likely represents an athalassic (inland) lake system evolving through times, the stable isotope composition (C, O and Sr) of carbonates strongly suggests the occurrence of transient connections of the ASCI lake water with water bodies influenced by seawater and/or fed with sulfates deriving from Triassic evaporites. The Issirac Basin may be therefore interpreted as a sill area connecting the ASCI lacustrine system with the Rhône valley (Mormoiron and Valence) saline lake systems during maximum flooding periods. Finally, changes in depositional features, biota and stable isotope composition of carbonates in unit U3 suggest a transition from relatively dry to more humid climate during the uppermost Priabonian or earliest Rupelian.

Time-and-ID-Based Proxy Reencryption Scheme

Directory of Open Access Journals (Sweden)

Kambombo Mtonga

2014-01-01

Full Text Available Time- and ID-based proxy reencryption scheme is proposed in this paper in which a type-based proxy reencryption enables the delegator to implement fine-grained policies with one key pair without any additional trust on the proxy. However, in some applications, the time within which the data was sampled or collected is very critical. In such applications, for example, healthcare and criminal investigations, the delegatee may be interested in only some of the messages with some types sampled within some time bound instead of the entire subset. Hence, in order to carter for such situations, in this paper, we propose a time-and-identity-based proxy reencryption scheme that takes into account the time within which the data was collected as a factor to consider when categorizing data in addition to its type. Our scheme is based on Boneh and Boyen identity-based scheme (BB-IBE and Matsuo’s proxy reencryption scheme for identity-based encryption (IBE to IBE. We prove that our scheme is semantically secure in the standard model.

Assessment of the Coral Temperature Proxies for Orbicella faveolata in the Southwestern Gulf of Mexico

Science.gov (United States)

Vara, M. A.; DeLong, K. L.; Herrmann, A. D.; Ouellette, G., Jr.; Richey, J. N.

2017-12-01

Coral Sr/Ca is a robust proxy of sea surface temperature (SST); however, discrepancies in the Sr/Ca-SST relationship among colonies of the same species may reduce confidence in absolute temperature reconstructions. Furthermore, terrestrial carbonate weathering can provide local sources of Sr and/or Ca to coastal waters that may disrupt the temperature-based coral Sr/Ca signal. Thus other trace metal SST proxies have been suggested to circumvent these issues (Li/Ca, Li/Mg, and Sr-U). Coral Ba/Ca has been used as a proxy for runoff and coastal upwelling, and therefore may be used to identify intervals when these processes overprint the Sr/Ca-SST signal. This study tests multiple coral SST proxies using reproducibility assessments to determine the best performing SST proxy. We conduct these assessments with cores recovered in 1991 by the U.S. Geological Survey from five Orbicella faveolata colonies from three reefs offshore of Veracruz, Mexico (19.06°N, 96.93°W) in water depths varying from 3 to 12 m. Previous studies found micromilling the complex skeletal structure of O. faveolata challenging and that monthly resolution may not recover full seasonal cycles. We use a laser ablation inductively coupled plasma mass spectrometer to simultaneously sample this coral's structure at weekly intervals spanning 8 years for Li/Ca, Li/Mg, Sr-U, Sr/Ca, and Ba/Ca. Here we found coral Li/Ca means and seasonal variations are similar among colonies thus this proxy may capture absolute temperature and SST variability. Similar to previous research with Porites corals, Li/Ca in these O. faveolata corals decreases with increases in SST with similar slopes and intercepts. During the last 10 years of these corals' lives, coral Sr/Ca analysis reveals a mean shift among colonies suggesting an external source could have disrupted the Sr/Ca signal, possibly seasonal runoff and/or winter upwelling common to Veracruz waters. Coral Ba/Ca analyses reveals elevated values in winters that coincide

Human rights of children with intellectual disabilities: comparing self-ratings and proxy ratings.

Science.gov (United States)

Huus, K; Granlund, M; Bornman, J; Lygnegård, F

2015-11-01

A child rights-based approach to research articulates well with Article 12 of the United Nations Convention on the Rights of the Child (CRC) and highlights the importance and value of including children's own views about aspects that concern them. The aim of this study is to compare children with intellectual disability's own ratings (as self-raters) to those of their primary caregivers (as proxy raters) regarding human rights of children. The study also aims to establish whether there is an inter-rater agreement between the self-raters and proxy raters concerning Maslow's hierarchy of needs. This study is nested in a larger study examining the human rights of children with intellectual disability in South Africa. In total, 162 children with intellectual disability from 11 schools across three provinces and their primary caregivers participated by answering parts of a Children's Rights Questionnaire (CRQ) developed by the researchers based on the United Nation's CRC. We compared the answers for six questions in the questionnaire that were addressed to self-raters (children) and proxy raters (primary caregivers) in the same way. Questions regarding basic needs, such as access to clean water or whether the child had food to eat at home, were answered similarly by self-raters and proxy raters. Larger differences were found when self-raters and proxy raters were asked about whether the child had things or friends to play with at home. Socio-economic variables seemed to affect whether self-raters and proxy raters answered similarly. The results underscore the importance of promoting children's rights to express themselves by considering the opinions of both the children as self-raters and their primary caregivers as proxy raters - not only the latter. The results indicate that it is especially important to include children's own voices when more complex needs are surveyed. Agreement between self- and proxy ratings could be affected by socio-economic circumstances. �

Long-memory and the sea level-temperature relationship: a fractional cointegration approach.

Science.gov (United States)

Ventosa-Santaulària, Daniel; Heres, David R; Martínez-Hernández, L Catalina

2014-01-01

Through thermal expansion of oceans and melting of land-based ice, global warming is very likely contributing to the sea level rise observed during the 20th century. The amount by which further increases in global average temperature could affect sea level is only known with large uncertainties due to the limited capacity of physics-based models to predict sea levels from global surface temperatures. Semi-empirical approaches have been implemented to estimate the statistical relationship between these two variables providing an alternative measure on which to base potentially disrupting impacts on coastal communities and ecosystems. However, only a few of these semi-empirical applications had addressed the spurious inference that is likely to be drawn when one nonstationary process is regressed on another. Furthermore, it has been shown that spurious effects are not eliminated by stationary processes when these possess strong long memory. Our results indicate that both global temperature and sea level indeed present the characteristics of long memory processes. Nevertheless, we find that these variables are fractionally cointegrated when sea-ice extent is incorporated as an instrumental variable for temperature which in our estimations has a statistically significant positive impact on global sea level.

An inexact multi-objective programming approach for strategic environmental assessment on regional development plan

Institute of Scientific and Technical Information of China (English)

WANG Jihua; GUO Huaicheng; LIU Lei; HAO Mingjia; ZHANG Ming; LU Xiaojian; XING Kexia

2004-01-01

This paper presents the development of an inexact multi-objective programming (IMOP) model and its application to the strategic environmental assessment (SEA) for the regional development plan for the Hunnan New Zone (HNZ) in Shenyang City, China. Inexact programming and multi-objective programming methods are employed to effectively account for extensive uncertainties in the study system and to reflect various interests from different stakeholders, respectively. In the case study, balancing-economy-and-environment scenario and focusing-industry-development scenario are analyzed by the interactive solution process for addressing the preferences from local authorities and compromises among different objectives. Through interpreting the model solutions under both scenarios, analysis of industrial structure, waste water treatment plant(WWTP) expansion, water consumption and pollution generation and treatment are undertaken for providing a solid base to justify and evaluate the HNZ regional development plan. The study results show that the developed IMOP-SEA framework is feasible and applicable in carrying comprehensive environmental impact assessments for development plan in a more effective and efficient manner.

Export of microplastics from land to sea. A modelling approach.

Science.gov (United States)

Siegfried, Max; Koelmans, Albert A; Besseling, Ellen; Kroeze, Carolien

2017-12-15

Quantifying the transport of plastic debris from river to sea is crucial for assessing the risks of plastic debris to human health and the environment. We present a global modelling approach to analyse the composition and quantity of point-source microplastic fluxes from European rivers to the sea. The model accounts for different types and sources of microplastics entering river systems via point sources. We combine information on these sources with information on sewage management and plastic retention during river transport for the largest European rivers. Sources of microplastics include personal care products, laundry, household dust and tyre and road wear particles (TRWP). Most of the modelled microplastics exported by rivers to seas are synthetic polymers from TRWP (42%) and plastic-based textiles abraded during laundry (29%). Smaller sources are synthetic polymers and plastic fibres in household dust (19%) and microbeads in personal care products (10%). Microplastic export differs largely among European rivers, as a result of differences in socio-economic development and technological status of sewage treatment facilities. About two-thirds of the microplastics modelled in this study flow into the Mediterranean and Black Sea. This can be explained by the relatively low microplastic removal efficiency of sewage treatment plants in the river basins draining into these two seas. Sewage treatment is generally more efficient in river basins draining into the North Sea, the Baltic Sea and the Atlantic Ocean. We use our model to explore future trends up to the year 2050. Our scenarios indicate that in the future river export of microplastics may increase in some river basins, but decrease in others. Remarkably, for many basins we calculate a reduction in river export of microplastics from point-sources, mainly due to an anticipated improvement in sewage treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

8000 years of coastal changes on a western Mediterranean island: A multiproxy approach from the Posada plain of Sardinia

DEFF Research Database (Denmark)

Melis, Rita T.; Di Rita, Federico; French, Charles

2018-01-01

-stratigraphy exhibited by a series of new cores taken from the coastal plain. This new study elucidates the main paleoecological changes, phases of shoreline migration and relative sea-level change during the last 8000 years. These results indicate the major role of sea-level stabilization and high sediment supply...... in driving major landscape changes, especially during the Neolithic period (6th–4th millennia BC), and the long-term settlement history of this coastal valley area. It is concluded that human occupation of the coastal plain, from prehistoric to historical times, was most likely constrained by the rapid......A multi-proxy palaeoenvironmental investigation was conducted to reconstruct the Holocene history of coastal landscape change in the lower Posada coastal plain of eastern Sardinia. In the Mediterranean region, coastal modifications during the Holocene have been driven by a complex interplay between...

Time-and-ID-Based Proxy Reencryption Scheme

OpenAIRE

Mtonga, Kambombo; Paul, Anand; Rho, Seungmin

2014-01-01

Time- and ID-based proxy reencryption scheme is proposed in this paper in which a type-based proxy reencryption enables the delegator to implement fine-grained policies with one key pair without any additional trust on the proxy. However, in some applications, the time within which the data was sampled or collected is very critical. In such applications, for example, healthcare and criminal investigations, the delegatee may be interested in only some of the messages with some types sampled wi...

Web Proxy Auto Discovery for the WLCG

Science.gov (United States)

Dykstra, D.; Blomer, J.; Blumenfeld, B.; De Salvo, A.; Dewhurst, A.; Verguilov, V.

2017-10-01

All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids registered in the ATLAS Grid Information System (AGIS) and CMS SITECONF files, cross-checked with squids registered by sites in the Grid Configuration Database (GOCDB) and the OSG Information Management (OIM) system, and combined with some exceptions manually configured by people from ATLAS and CMS who operate WLCG Squid monitoring. WPAD servers at CERN respond to http requests from grid nodes all over the world with a PAC file that lists available web proxies, based on IP addresses matched from a database that contains the IP address ranges registered to organizations. Large grid sites are encouraged to supply their own WPAD web servers for more flexibility, to avoid being affected by short term long distance network outages, and to offload the WLCG WPAD servers at CERN. The CERN WPAD servers additionally support requests from jobs running at non-grid sites (particularly for LHC@Home) which they direct to the nearest publicly accessible web proxy servers. The responses

Multi-model ensemble combinations of the water budget in the East/Japan Sea

Science.gov (United States)

HAN, S.; Hirose, N.; Usui, N.; Miyazawa, Y.

2016-02-01

The water balance of East/Japan Sea is determined mainly by inflow and outflow through the Korea/Tsushima, Tsugaru and Soya/La Perouse Straits. However, the volume transports measured at three straits remain quantitatively unbalanced. This study examined the seasonal variation of the volume transport using the multiple linear regression and ridge regression of multi-model ensemble (MME) methods to estimate physically consistent circulation in East/Japan Sea by using four different data assimilation models. The MME outperformed all of the single models by reducing uncertainties, especially the multicollinearity problem with the ridge regression. However, the regression constants turned out to be inconsistent with each other if the MME was applied separately for each strait. The MME for a connected system was thus performed to find common constants for these straits. The estimation of this MME was found to be similar to the MME result of sea level difference (SLD). The estimated mean transport (2.42 Sv) was smaller than the measurement data at the Korea/Tsushima Strait, but the calibrated transport of the Tsugaru Strait (1.63 Sv) was larger than the observed data. The MME results of transport and SLD also suggested that the standard deviation (STD) of the Korea/Tsushima Strait is larger than the STD of the observation, whereas the estimated results were almost identical to that observed for the Tsugaru and Soya/La Perouse Straits. The similarity between MME results enhances the reliability of the present MME estimation.

Generating multi-double-scroll attractors via nonautonomous approach

Energy Technology Data Exchange (ETDEWEB)

Hong, Qinghui; Xie, Qingguo, E-mail: qgxie@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Wuhan 430074 (China); Shen, Yi; Wang, Xiaoping [School of Automation, Huazhong University of Science and Technology, Wuhan 430074 (China)

2016-08-15

It is a common phenomenon that multi-scroll attractors are realized by introducing the various nonlinear functions with multiple breakpoints in double scroll chaotic systems. Differently, we present a nonautonomous approach for generating multi-double-scroll attractors (MDSA) without changing the original nonlinear functions. By using the multi-level-logic pulse excitation technique in double scroll chaotic systems, MDSA can be generated. A Chua's circuit, a Jerk circuit, and a modified Lorenz system are given as designed example and the Matlab simulation results are presented. Furthermore, the corresponding realization circuits are designed. The Pspice results are in agreement with numerical simulation results, which verify the availability and feasibility of this method.

A multi-proxy chronological reconstruction of palaeosalinity in the eastern Limfjord, Denmark

Science.gov (United States)

Weiss, Gabriella; Reimer, Paula; Lewis, Jonathan

2015-04-01

The Jutland peninsula in northern Denmark is home to the Limfjord, one of the largest estuarine bodies of water in the region. Human inhabitance of the Limfjord's surrounding coastlines stretches back further than 7,800 cal BP, with anthropogenic influence on the landscape beginning approximately 6,000 cal BP. Understanding how the Limfjord as a system has changed throughout time is useful in comprehending subsistence patterns and anthropogenic influence. This research is part of a larger project aimed at discerning subsistence patterns and environmental change in the region. Following the Younger Dryas, as the Fennoscandian ice sheet began to melt, Denmark experienced isostatic rebound, which contributed to the complex sea level history in the region. Between ice melt and isostatic rebound, the Jutland peninsula experienced many transgression and regression events. Connections to surrounding seas have shifted throughout time, with most attention focused on the western connection of the Limfjord with the North Sea, which has experienced numerous closures and subsequent re-openings throughout the Holocene. Furthermore, the Limfjord-North Sea connection has been the focal point of research because of the west to east water flow in the system, and the present day higher salinity in the west compared to the east. Little to no consideration has been paid to the influence of the Kattegat and Baltic on the Limfjord until now. A 10m sediment core was taken from Sebbersund (near Nibe, Limfjord), along the connection between the Limfjord and the Kattegat in the east to understand how the eastern part of the system has changed and differed from changes observed in the west. The Sebbersund sequence spans a majority of the Holocene, from 9600 cal BP to 1030 cal BP, determined via radiocarbon dating of terrestrial macrofossils and bulk sediment. Over this time period palaeoenvironmental conditions were reconstructed through the use of geochemical analyses (δ13C, δ15N, C

The Proxy Challenge: Why bespoke proxy indicators can help solve the anti-corruption measurement problem

OpenAIRE

Johnsøn, Jesper; Mason, Phil

2013-01-01

Practitioners working in anti-corruption face perennial challenges in measuring changes in corruption levels and evaluating whether anti-corruption efforts are successful. These two challenges are linked but not inseparable. To make progress on the latter front, that is, evaluating whether anti-corruption efforts are having an impact, the U4 Anti-Corruption Resource Centre and the UK Department for International Development are launching an exploration into the use of proxy indicators. Proxy ...

Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System

Science.gov (United States)

McGann, Mary; Erikson, Li H.; Wan, Elmira; Powell, Charles; Maddocks, Rosalie F.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processes. The biota will be spatially distributed according to its response to environmental parameters such as water temperature, salinity, dissolved oxygen, organic carbon content, grain size, and intensity of currents and tidal flow, whereas the presence of anthropogenic and volcanic constituents will reflect proximity to source areas and whether they are fluvially- or aerially-transported. Because each of these constituents have a unique environmental signature, they are a more precise proxy for that source area than the conventional sedimentary process indicators. This San Francisco Bay Coastal System study demonstrates that by applying a multi-proxy approach, the primary sites of sediment transport can be identified. Many of these sites are far from where the constituents originated, showing that sediment transport is widespread in the region. Although not often used, identifying and interpreting the distribution of naturally-occurring and allochthonous biologic, anthropogenic, and volcanic sediment constituents is a powerful tool to aid in the investigation of sediment transport pathways in other coastal systems.

Changing ‘Multi-Problem Families’ – Developing a Multi-Contextual Systemic Approach

Directory of Open Access Journals (Sweden)

2007-05-01

Full Text Available Over the past 30 years the Marlborough Family Service in London has pioneered multi-family work with marginalized families presenting simultaneously with abuse and neglect, family violence, substance misuse, educational failure and mental illness. The approach is based on a systemic multi-contextual mode and this chapter describes the evolving work, including the establishment of the first permanent multiple family day setting, specifically designed for and solely dedicated to the work with seemingly ‘hopeless’ families. The ingredients of ‘therapeutic assessments’ of parents and families are outlined and the importance of initial network meetings with professionals and family members is emphasized.

A scaling approach to project regional sea level rise and its uncertainties

Directory of Open Access Journals (Sweden)

M. Perrette

2013-01-01

Full Text Available Climate change causes global mean sea level to rise due to thermal expansion of seawater and loss of land ice from mountain glaciers, ice caps and ice sheets. Locally, sea level can strongly deviate from the global mean rise due to changes in wind and ocean currents. In addition, gravitational adjustments redistribute seawater away from shrinking ice masses. However, the land ice contribution to sea level rise (SLR remains very challenging to model, and comprehensive regional sea level projections, which include appropriate gravitational adjustments, are still a nascent field (Katsman et al., 2011; Slangen et al., 2011. Here, we present an alternative approach to derive regional sea level changes for a range of emission and land ice melt scenarios, combining probabilistic forecasts of a simple climate model (MAGICC6 with the new CMIP5 general circulation models. The contribution from ice sheets varies considerably depending on the assumptions for the ice sheet projections, and thus represents sizeable uncertainties for future sea level rise. However, several consistent and robust patterns emerge from our analysis: at low latitudes, especially in the Indian Ocean and Western Pacific, sea level will likely rise more than the global mean (mostly by 10–20%. Around the northeastern Atlantic and the northeastern Pacific coasts, sea level will rise less than the global average or, in some rare cases, even fall. In the northwestern Atlantic, along the American coast, a strong dynamic sea level rise is counteracted by gravitational depression due to Greenland ice melt; whether sea level will be above- or below-average will depend on the relative contribution of these two factors. Our regional sea level projections and the diagnosed uncertainties provide an improved basis for coastal impact analysis and infrastructure planning for adaptation to climate change.

Regulation of CO2 Air Sea Fluxes by Sediments in the North Sea

Science.gov (United States)

Burt, William; Thomas, Helmuth; Hagens, Mathilde; Brenner, Heiko; Pätsch, Johannes; Clargo, Nicola; Salt, Lesley

2016-04-01

A multi-tracer approach is applied to assess the impact of boundary fluxes (e.g. benthic input from sediments or lateral inputs from the coastline) on the acid-base buffering capacity, and overall biogeochemistry, of the North Sea. Analyses of both basin-wide observations in the North Sea and transects through tidal basins at the North-Frisian coastline, reveal that surface distributions of the δ13C signature of dissolved inorganic carbon (DIC) are predominantly controlled by a balance between biological production and respiration. In particular, variability in metabolic DIC throughout stations in the well-mixed southern North Sea indicates the presence of an external carbon source, which is traced to the European continental coastline using naturally-occurring radium isotopes (224Ra and 228Ra). 228Ra is also shown to be a highly effective tracer of North Sea total alkalinity (AT) compared to the more conventional use of salinity. Coastal inputs of metabolic DIC and AT are calculated on a basin-wide scale, and ratios of these inputs suggest denitrification as a primary metabolic pathway for their formation. The AT input paralleling the metabolic DIC release prevents a significant decline in pH as compared to aerobic (i.e. unbuffered) release of metabolic DIC. Finally, long-term pH trends mimic those of riverine nitrate loading, highlighting the importance of coastal AT production via denitrification in regulating pH in the southern North Sea.

Fluctuations in productivity and denitrification in the southeastern Arabian Sea during the Late Quaternary

Digital Repository Service at National Institute of Oceanography (India)

Kessarkar, P; Rao, V.P; Naqvi, S.W.A.; Chivas, A.R.; Saino, T.

Sedimentological and stable isotopic characteristics of sediments have been studied in a core from the southeastern Arabian Sea containing records of the past 70 ka. Palaeoproductivity proxies such as organic carbon (C sub(org)), total nitrogen (TN...

The Last Interglacial-Glacial cycle (MIS 5-2) re-examined based on long proxy records from central and northern Europe

Science.gov (United States)

Helmens, Karin F.

2014-02-01

characterized the climate variability of MIS 3. Mild climate conditions in early MIS 3 caused large-scale deglaciation of the Fennoscandian Ice Sheet, and ice-free conditions with Betula-dominated vegetation (including tree birch) persisted over large parts of Fennoscandia, possibly interrupted by glaciation, during major part of MIS 3 till ca 35 ka BP. Overall, MIS 5 was mostly mild with warmest or peak interglacial conditions at the very start during MIS 5e. MIS 4-2 was mostly cold with most extreme or peak glacial conditions in the closing phase during MIS 2. This points to a subdivision of the last climate cycle into an early, overall mild interglacial half and a late, overall cold glacial half, each with duration of ca 50 ka. This review also shows that the climate variability in central and northern Europe during the LI-G cycle was mostly in degrees of continentality with major shifts in winter temperature and precipitation values; summer temperatures, on the other hand, remained largely unchanged. It points to the waxing and waning of sea-ice over the North Atlantic Ocean as a possible characteristic feature of the Late Pleistocene. The present compilation, based on long terrestrial sequences, high-resolution multi-proxy data from the oceans, and quantified paleo-climate data, strongly favors a definition of entire Marine Oxygen Isotope Stage 5 as the Last Interglacial similar as in the original marine stratigraphy and the stratigraphy at La Grande Pile in France. The proxy-based climate data places the start of the Last Glacial at the base of MIS 4 and the northwest European Pleniglacial. It shows that the division between the Eemian (MIS 5e) and the Early Weichselian (MIS 5d-a) is not useful, as not relevant from a climate point of view.

Fluorescence measured in situ as a proxy of CDOM absorption and DOC concentration in the Baltic Sea

Directory of Open Access Journals (Sweden)

Piotr Kowalczuk

2010-09-01

measured in filtered and raw water (R2 = 0.61 and R2 = 0.56. The seasonal cycle had an impact on the relationship between DOC and CDOM optical properties. The hyperbolic relationships between aCDOM(370 vs. carbon-specific absorption coefficient a*CDOM(370, and IFl vs. the ratio of fluorescence intensity to organic carbon concentration IFl/DOC were very good. The discharge and mixing of riverine waters is a primary driver of variability in DOC and CDOM optical properties in the surface waters of the southern Baltic Sea, since all the parameters considered are negatively correlated with salinity. It was found that there was a positive trend of increasing values of DOM optical parameters with salinity increase (within a range of 8-12 in deep water below the permanent pycnocline. Evidence is also presented to show that late-summer photodegradation was responsible for the depletion of CDOM florescence intensities in the mixed layer above the seasonal thermocline. It was further demonstrated that the DOC concentration increases in the stagnant waters of the Baltic Sea deeps. The Integrated Optical-Hydrological Probe, which registers high-resolution vertical profiles of salinity, temperature, CDOM and the optical properties of water, confirmed that DOM optical proxies can be used in studies of DOM biogeochemical cycles in the Baltic Sea.

A multi-proxy approach to understanding complex responses of salt-lake catchments to climate variability and human pressure: A Late Quaternary case study from south-eastern, Spain

Science.gov (United States)

Jones, Samantha Elsie; Burjachs, Francesc; Ferrer-García, Carlos; Giralt, Santiago; Schulte, Lothar; Fernández-López de Pablo, Javier

2018-03-01

This article focuses on a former salt lake in the upper Vinalopó Valley in south-eastern Spain. The study spans the Late Pleistocene through to the Late Holocene, although with particular focus on the period between 11 ka cal BP and 3000 ka cal BP (which spans the Mesolithic and part of the Bronze Age). High resolution multi-proxy analysis (including pollen, non pollen palynomorphs, grain size, X-ray fluorescence and X-ray diffraction) was undertaken on the lake sediments. The results show strong sensitivity to both long term and small changes in the evaporation/precipitation ratio, affecting the surrounding vegetation composition, lake-biota and sediment geochemistry. To summarise the key findings the main general trends identified include: 1) Hyper-saline conditions and low lake levels at the end of the Late Glacial 2) Increasing wetness and temperatures which witnessed an expansion of mesophilic woodland taxa, lake infilling and the establishment of a more perennial lake system at the onset of the Holocene 3) An increase in solar insolation after 9 ka cal BP which saw the re-establishment of pine forests 4) A continued trend towards increasing dryness (climatic optimum) at 7 ka cal BP but with continued freshwater input 5) An increase in sclerophyllous open woody vegetation (anthropogenic?), and increasing wetness (climatic?) is represented in the lake record between 5.9 and 3 ka cal BP 6) The Holocene was also punctuated by several aridity pulses, the most prominent corresponding to the 8.2 ka cal BP event. These events, despite a paucity of well dated archaeological sites in the surrounding area, likely altered the carrying capacity of this area both regionally and locally, particularly during the Mesolithic-Neolithic transition, in terms of fresh water supply for human/animal consumption, wild plant food reserves and suitable land for crop growth.

A multi-decadal wind-wave hindcast for the North Sea 1949-2014: coastDat2

Science.gov (United States)

Groll, Nikolaus; Weisse, Ralf

2017-12-01

Long and consistent wave data are important for analysing wave climate variability and change. Moreover, such wave data are also needed in coastal and offshore design and for addressing safety-related issues at sea. Using the third-generation spectral wave model WAM a multi-decadal wind-wave hindcast for the North Sea covering the period 1949-2014 was produced. The hindcast is part of the coastDat database representing a consistent and homogeneous met-ocean data set. It is shown that despite not being perfect, data from the wave hindcast are generally suitable for wave climate analysis. In particular, comparisons of hindcast data with in situ and satellite observations show on average a reasonable agreement, while a tendency towards overestimation of the highest waves could be inferred. Despite these limitations, the wave hindcast still provides useful data for assessing wave climate variability and change as well as for risk analysis, in particular when conservative estimates are needed. Hindcast data are stored at the World Data Center for Climate (WDCC) and can be freely accessed using the doi:10.1594/WDCC/coastDat-2_WAM-North_Sea Groll and Weisse(2016) or via the coastDat web-page http://www.coastdat.de.

A case for multi-model and multi-approach based event attribution: The 2015 European drought

Science.gov (United States)

Hauser, Mathias; Gudmundsson, Lukas; Orth, René; Jézéquel, Aglaé; Haustein, Karsten; Seneviratne, Sonia Isabelle

2017-04-01

Science on the role of anthropogenic influence on extreme weather events such as heat waves or droughts has evolved rapidly over the past years. The approach of "event attribution" compares the occurrence probability of an event in the present, factual world with the probability of the same event in a hypothetical, counterfactual world without human-induced climate change. Every such analysis necessarily faces multiple methodological choices including, but not limited to: the event definition, climate model configuration, and the design of the counterfactual world. Here, we explore the role of such choices for an attribution analysis of the 2015 European summer drought (Hauser et al., in preparation). While some GCMs suggest that anthropogenic forcing made the 2015 drought more likely, others suggest no impact, or even a decrease in the event probability. These results additionally differ for single GCMs, depending on the reference used for the counterfactual world. Observational results do not suggest a historical tendency towards more drying, but the record may be too short to provide robust assessments because of the large interannual variability of drought occurrence. These results highlight the need for a multi-model and multi-approach framework in event attribution research. This is especially important for events with low signal to noise ratio and high model dependency such as regional droughts. Hauser, M., L. Gudmundsson, R. Orth, A. Jézéquel, K. Haustein, S.I. Seneviratne, in preparation. A case for multi-model and multi-approach based event attribution: The 2015 European drought.

[Monitoring "green tide" in the Yellow Sea and the East China Sea using multi-temporal and multi-source remote sensing images].

Science.gov (United States)

Xing, Qian-Guo; Zheng, Xiang-Yang; Shi, Ping; Hao, Jia-Jia; Yu, Ding-Feng; Liang, Shou-Zhen; Liu, Dong-Yan; Zhang, Yuan-Zhi

2011-06-01

Landsat-TM (Theme Mapper) and EOS (Earth Observing System)-MODIS (MODerate resolution Imaging Spectrora-diometer) Terra/Aqua images were used to monitor the macro-algae (Ulva prolifera) bloom since 2007 at the Yellow Sea and the East China Sea. At the turbid waters of Northern Jiangsu Shoal, there is strong spectral mixing behavior, and satellite images with finer spatical resolution are more effective in detection of macro-algae patches. Macro-algae patches were detected by the Landsat images for the first time at the Sheyang estuary where is dominated by very turbid waters. The MODIS images showed that the macro-algae from the turbid waters near the Northern Jiangsu Shoal drifted southwardly in the early of May and affected the East China Sea waters; with the strengthening east-asian Summer Monsoon, macro-algae patches mainly drifted in a northward path which was mostly observed at the Yellow Sea. Macro-algae patches were also found to drift eastwardly towards the Korea Peninsular, which are supposed to be driven by the sea surface wind.

Efficient Conditional Proxy Re-encryption with Chosen-Ciphertext Security

NARCIS (Netherlands)

Weng, Jiang; Yang, Yanjiang; Tang, Qiang; Deng, Robert H.; Bao, Feng

Recently, a variant of proxy re-encryption, named conditional proxy re-encryption (C-PRE), has been introduced. Compared with traditional proxy re-encryption, C-PRE enables the delegator to implement fine-grained delegation of decryption rights, and thus is more useful in many applications. In this

Optimizing TCP Performance over UMTS with Split TCP Proxy

DEFF Research Database (Denmark)

Hu, Liang; Dittmann, Lars

2009-01-01

. To cope with large delay bandwidth product, we propose a novel concept of split TCP proxy which is placed at GGSN between UNITS network and Internet. The split proxy divides the bandwidth delay product into two parts, resulting in two TCP connections with smaller bandwidth delay products which can...... be pipelined and thus operating at higher speeds. Simulation results show, the split TCP proxy can significantly improve the TCP performance in terms of RLC throughput under high bit rate DCH channel scenario (e.g.256 kbps). On the other hand, it only brings small performance improvement under low bit rate DCH...... scenario (e.g.64 kbps). Besides, the split TCP proxy brings more performance gain for downloading large files than downloading small ones. To the end, for the configuration of the split proxy, an aggressive initial TCP congestion window size (e.g. 10 MSS) at proxy is particularly useful for radio links...

Material properties identification using ultrasonic waves and laser Doppler vibrometer measurements: a multi-input multi-output approach

International Nuclear Information System (INIS)

Longo, R; Vanlanduit, S; Guillaume, P

2013-01-01

In this paper a multi-input multi-output approach able to determine the material properties of homogeneous materials is presented. To do so, an experimental set-up which combines the use of multi harmonic signals with interleaved frequencies and laser Doppler vibrometer measurements has been developed. A modeling technique, based on transmission and reflection measurements, allowed the simultaneous determination of longitudinal wave velocity, density and thickness of the materials under test with high levels of precision and accuracy. (paper)

Multi-actor involvement for integrating ecosystem services in strategic environmental assessment of spatial plans

International Nuclear Information System (INIS)

Rozas-Vásquez, Daniel; Fürst, Christine; Geneletti, Davide; Muñoz, Francisco

2017-01-01

Integrating an ecosystem services (ES) approach into Strategic Environmental Assessment (SEA) of spatial plans potentially enhances the consideration of the value of nature in decision making and policy processes. However, there is increasing concern about the institutional context and a lack of a common understanding of SEA and ecosystem services for adopting them as an integrated framework. This paper addresses this concern by analysing the current understanding and network relations in a multi-actor arrangement as a first step towards a successful integration of ES in SEA and spatial planning. Our analysis focuses on a case study in Chile, where we administered a questionnaire survey to some of the main actors involved in the spatial planning process. The questionnaire focused on issues such as network relations among actors and on conceptual understanding, perceptions and challenges for integrating ES in SEA and spatial planning, knowledge on methodological approaches, and the connections and gaps in the science-policy interface. Our findings suggest that a common understanding of SEA and especially of ES in a context of multiple actors is still at an initial stage in Chile. Additionally, the lack of institutional guidelines and methodological support is considered the main challenge for integration. We conclude that preconditions exist in Chile for integrating ES in SEA for spatial planning, but they strongly depend on appropriate governance schemes that promote a close science-policy interaction, as well as collaborative work and learning. - Highlights: • Linking ecosystem services in SEA is an effective framework for sustainability. • Multi-actor understanding and networks in ecosystem services and SEA were analyzed. • Understanding of SEA and especially of ES is still in an initial stage in Chile. • A lack of institutional guidelines is one of the key challenges for this link.

Multi-actor involvement for integrating ecosystem services in strategic environmental assessment of spatial plans

Energy Technology Data Exchange (ETDEWEB)

Rozas-Vásquez, Daniel, E-mail: danielrozas@gmail.com [Center for Development Research, Dept. Ecology and Natural Resources Management, University of Bonn, Walter Flex Str. 3, 53113 Bonn (Germany); Laboratorio de Planificación Territorial, Universidad Católica de Temuco, Rudecindo ortega, 02950 Temuco (Chile); Fürst, Christine [Martin Luther University Halle-Wittenberg, Dept. Natural Sciences III, Institute for Geosciences and Geography, Von Seckendorff-Platz 4, 06120 Halle-Saale (Germany); Geneletti, Davide [University of Trento, Department of Civil, Environmental and Mechanical Engineering, via Mesiano, 77, Trento 38123 (Italy); Muñoz, Francisco [Laboratorio de Planificación Territorial, Universidad Católica de Temuco, Rudecindo ortega, 02950 Temuco (Chile)

2017-01-15

Integrating an ecosystem services (ES) approach into Strategic Environmental Assessment (SEA) of spatial plans potentially enhances the consideration of the value of nature in decision making and policy processes. However, there is increasing concern about the institutional context and a lack of a common understanding of SEA and ecosystem services for adopting them as an integrated framework. This paper addresses this concern by analysing the current understanding and network relations in a multi-actor arrangement as a first step towards a successful integration of ES in SEA and spatial planning. Our analysis focuses on a case study in Chile, where we administered a questionnaire survey to some of the main actors involved in the spatial planning process. The questionnaire focused on issues such as network relations among actors and on conceptual understanding, perceptions and challenges for integrating ES in SEA and spatial planning, knowledge on methodological approaches, and the connections and gaps in the science-policy interface. Our findings suggest that a common understanding of SEA and especially of ES in a context of multiple actors is still at an initial stage in Chile. Additionally, the lack of institutional guidelines and methodological support is considered the main challenge for integration. We conclude that preconditions exist in Chile for integrating ES in SEA for spatial planning, but they strongly depend on appropriate governance schemes that promote a close science-policy interaction, as well as collaborative work and learning. - Highlights: • Linking ecosystem services in SEA is an effective framework for sustainability. • Multi-actor understanding and networks in ecosystem services and SEA were analyzed. • Understanding of SEA and especially of ES is still in an initial stage in Chile. • A lack of institutional guidelines is one of the key challenges for this link.

Family factors in end-of-life decision-making: family conflict and proxy relationship.

Science.gov (United States)

Parks, Susan Mockus; Winter, Laraine; Santana, Abbie J; Parker, Barbara; Diamond, James J; Rose, Molly; Myers, Ronald E

2011-02-01

Few studies have examined proxy decision-making regarding end-of-life treatment decisions. Proxy accuracy is defined as whether proxy treatment choices are consistent with the expressed wishes of their index elder. The purpose of this study was to examine proxy accuracy in relation to two family factors that may influence proxy accuracy: perceived family conflict and type of elder-proxy relationship. Telephone interviews with 202 community-dwelling elders and their proxy decision makers were conducted including the Life-Support Preferences Questionnaire (LSPQ), and a measure of family conflict, and sociodemographic characteristics, including type of relationship. Elder-proxy accuracy was associated with the type of elder-proxy relationship. Adult children demonstrated the lowest elder-proxy accuracy and spousal proxies the highest elder-proxy accuracy. Elder-proxy accuracy was associated with family conflict. Proxies reporting higher family conflict had lower elder-proxy accuracy. No interaction between family conflict and relationship type was revealed. Spousal proxies were more accurate in their substituted judgment than adult children, and proxies who perceive higher degree of family conflict tended to be less accurate than those with lower family conflict. Health care providers should be aware of these family factors when discussing advance care planning.

Examining the evidence for a recent acceleration in the rate of sea-level rise using combined instrumental and proxy data, North Carolina, USA

Science.gov (United States)

Kemp, A.; Horton, B. P.

2007-12-01

Whilst accelerated rates of relative sea-level (RSL) rise are potentially one of the most devastating impacts of future climate change, our understanding of decadal scale changes in sea-level is poor. This paper seeks to address this knowledge gap by combining tide gauge and high-precision geological reconstructions of relative sea-level of sufficient resolution and duration to detect any recent acceleration in the rate of sea-level rise. We offer a high resolution relative sea-level history for the last ~2000 years from the Albemarle - Pamlico Estuarine System in North Carolina. Contemporary foraminifera were collected from five back barrier marshes to create a regional scale modern training set. The use of multiple marshes from a region increases the ecological and environmental diversity included within the training set and reduces the probability of a no modern analogue outcome. To merge the five spatially distinct sites and to relate each to local tide levels we used the VDatum transformation tool. This method relates all samples to a common orthometric datum (NAVD88) and reduces error. We developed an accurate and precise transfer function to reconstruct former sea levels based upon the modern observable relationship between foraminifera and elevation with respect to the tidal frame. We applied the transfer function to salt-marsh core(s) from Sand Point (Roanoke Island), North Carolina to produce a late Holocene RSL record. An age-depth model was produced from composite chronologies of 210Pb, 14C and pollen chrono-horizons. We validated our approach by comparing geological based reconstructions and instrumental tide gauge records. Our records show that in the last ~2000 years sea level has risen at a background rate of ~1.1mm/yr. There is evidence for two recent accelerations in the rate of sea-level rise during the late 19th and 20th centuries to a current rate of ~4mm/yr.

The Effects of Temperature and Hydrostatic Pressure on Metal Toxicity: Insights into Toxicity in the Deep Sea.

Science.gov (United States)

Brown, Alastair; Thatje, Sven; Hauton, Chris

2017-09-05

Mineral prospecting in the deep sea is increasing, promoting concern regarding potential ecotoxicological impacts on deep-sea fauna. Technological difficulties in assessing toxicity in deep-sea species has promoted interest in developing shallow-water ecotoxicological proxy species. However, it is unclear how the low temperature and high hydrostatic pressure prevalent in the deep sea affect toxicity, and whether adaptation to deep-sea environmental conditions moderates any effects of these factors. To address these uncertainties we assessed the effects of temperature and hydrostatic pressure on lethal and sublethal (respiration rate, antioxidant enzyme activity) toxicity in acute (96 h) copper and cadmium exposures, using the shallow-water ecophysiological model organism Palaemon varians. Low temperature reduced toxicity in both metals, but reduced cadmium toxicity significantly more. In contrast, elevated hydrostatic pressure increased copper toxicity, but did not affect cadmium toxicity. The synergistic interaction between copper and cadmium was not affected by low temperature, but high hydrostatic pressure significantly enhanced the synergism. Differential environmental effects on toxicity suggest different mechanisms of action for copper and cadmium, and highlight that mechanistic understanding of toxicity is fundamental to predicting environmental effects on toxicity. Although results infer that sensitivity to toxicants differs across biogeographic ranges, shallow-water species may be suitable ecotoxicological proxies for deep-sea species, dependent on adaptation to habitats with similar environmental variability.

Indonesian Sea Accident Analysis (Case Study From 2003 – 2013)

Science.gov (United States)

Arya Dewanto, Y.; Faturachman, D.

2018-03-01

There are so many accidents in sea transportation in Indonesia. Most of the accidents happen because of low concern aspects of the safety and security of the crew. In sailing, a man as transport users to interact with the ship and the surrounding environment (including other ships, cruise lines, ports, and the situation of local conditions). These interactions are sometimes very complex and related to various aspects of. Aware of the multiplicity of aspects related to the third of these factors, seeking the safety of cruise through a reduction in the number of accidents and the risk of death and serious injuries due to accidents and goods transported is certainly not enough attempted through mono-sector approach, but rather takes a multi-sector approach to the efforts. In this paper, we described the Indonesian Sea Transportation accident analysis for eleven years divided into four items: total of ship accident type, ship accident factor, total of casualties, region of ship accidents. All data founded from Marine Court (Mahkamah Pelayaran). From that 4 items we can find Indonesia Sea Accident Analysis from 2003-2013.

Inter-annual to multi-decadal variability in prairie water resources over the past millennium

International Nuclear Information System (INIS)

Sauchyn, D.

2008-01-01

In the Prairie Provinces, declining levels have been recently recorded for various rivers and lakes, and further reductions are projected. These trends reflect human impact in terms of increasing water consumption and possibly anthropogenic climate change. From the coupling of hydrological models and climate change scenarios, researchers have projected lower future summer flows as global warming brings shorter warmer winters and longer and generally drier summers to western Canada. However, the detection and interpretation of trends from gauge records and model outputs are constrained by the relatively short perspective of decades and the uncertainties associated with projecting climate change and its impacts on hydrological regimes. A longer perspective on inter-annual to multi-decadal variability in water resources is available from moisture-sensitive tree-ring chronologies. We have established a dense network of low elevation chronologies spanning the headwaters of the Saskatchewan, Missouri, Churchill and Mackenzie River basins. Standardized tree-ring width for a large sample of trees and sites is a strong regional signal of annual and seasonal hydroclimate, and an especially good proxy of low water levels. Proxy streamflow records, up to 800 years in length, show quasi-periodic variability at inter-annual to multi-decadal scales that correspond to the tempo of sea-surface temperature anomalies. The industrial sponsors of our research, Manitoba Hydro and EPCOR, anticipate the use of our tree-ring reconstructions for informing forecasts of future water supplies and planning adaptation to climate change. Engineers from these companies, and more than 50 other water managers and planners from the Prairie Provinces, attended a workshop in March 2008 to explore potential applications of paleo-hydrological records to water resource management. (author)

A New Proxy Measurement Algorithm with Application to the Estimation of Vertical Ground Reaction Forces Using Wearable Sensors.

Science.gov (United States)

Guo, Yuzhu; Storm, Fabio; Zhao, Yifan; Billings, Stephen A; Pavic, Aleksandar; Mazzà, Claudia; Guo, Ling-Zhong

2017-09-22

Measurement of the ground reaction forces (GRF) during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF) from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR) is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0%) using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra). Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications.

A New Proxy Measurement Algorithm with Application to the Estimation of Vertical Ground Reaction Forces Using Wearable Sensors

Directory of Open Access Journals (Sweden)

Yuzhu Guo

2017-09-01

Full Text Available Measurement of the ground reaction forces (GRF during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0% using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra. Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications.

Design and implementation of Ad-Hoc collaborative proxying scheme for reducing network energy waste

Directory of Open Access Journals (Sweden)

Rafiullah Khan

2017-05-01

Full Text Available Network devices are equipped with low power states but they are rarely activated due to their inability of maintaining network connectivity. Recently, Network Connectivity Proxy (NCP concept has been proposed in literature as an effective mechanism to exploit full potential of low power features on network devices by impersonating their virtual presence. However, the NCP concept faces several open issues and challenges especially related to proxying of TCP connections and majority of daily used proprietary closed-source applications. This paper presents a new approach for reducing network energy waste through intelligent collaboration among daily used devices (e.g., desktop computers, laptops, tablets, smartphones, etc. It guarantees to run applications on only and only one user device that is under active use at that specific moment. To reduce energy waste and allow idle devices to sleep, our approach also takes benefit from a light-weight home gateway proxy with very basic practically realizable functionalities. The proposed system not just reduces energy waste of fixed devices but also enables mobile devices to significantly improve their battery life. Our developed software prototypes allow devices to autonomously and seamlessly collaborate with each other without requiring any configuration or user input. Further, this paper also presents the basic performance evaluation of developed prototypes in real networking environments.

A GIS-based multi-source and multi-box modeling approach (GMSMB) for air pollution assessment--a North American case study.

Science.gov (United States)

Wang, Bao-Zhen; Chen, Zhi

2013-01-01

This article presents a GIS-based multi-source and multi-box modeling approach (GMSMB) to predict the spatial concentration distributions of airborne pollutant on local and regional scales. In this method, an extended multi-box model combined with a multi-source and multi-grid Gaussian model are developed within the GIS framework to examine the contributions from both point- and area-source emissions. By using GIS, a large amount of data including emission sources, air quality monitoring, meteorological data, and spatial location information required for air quality modeling are brought into an integrated modeling environment. It helps more details of spatial variation in source distribution and meteorological condition to be quantitatively analyzed. The developed modeling approach has been examined to predict the spatial concentration distribution of four air pollutants (CO, NO(2), SO(2) and PM(2.5)) for the State of California. The modeling results are compared with the monitoring data. Good agreement is acquired which demonstrated that the developed modeling approach could deliver an effective air pollution assessment on both regional and local scales to support air pollution control and management planning.

Reconstructing Common Era relative sea-level change on the Gulf Coast of Florida

Science.gov (United States)

Gerlach, Matthew J.; Engelhart, Simon E.; Kemp, Andrew C.; Moyer, Ryan P.; Smoak, Joseph M.; Bernhardt, Christopher E.; Cahill, Niamh

2017-01-01

To address a paucity of Common Era data in the Gulf of Mexico, we reconstructed ~ 1.1 m of relative sea-level (RSL) rise over the past ~ 2000 years at Little Manatee River (Gulf Coast of Florida, USA). We applied a regional-scale foraminiferal transfer function to fossil assemblages preserved in a core of salt-marsh peat and organic silt that was dated using radiocarbon and recognition of pollution, 137Cs and pollen chronohorizons. Our proxy reconstruction was combined with tide-gauge data from four nearby sites spanning 1913–2014 CE. Application of an Errors-in-Variables Integrated Gaussian Process (EIV-IGP) model to the combined proxy and instrumental dataset demonstrates that RSL fell from ~ 350 to 100 BCE, before rising continuously to present. This initial RSL fall was likely the result of local-scale processes (e.g., silting up of a tidal flat or shallow sub-tidal shoal) as salt-marsh development at the site began. Since ~ 0 CE, we consider the reconstruction to be representative of regional-scale RSL trends. We removed a linear rate of 0.3 mm/yr from the RSL record using the EIV-IGP model to estimate climate-driven sea-level trends and to facilitate comparison among sites. This analysis demonstrates that since ~ 0 CE sea level did not deviate significantly from zero until accelerating continuously from ~ 1500 CE to present. Sea level was rising at 1.33 mm/yr in 1900 CE and accelerated until 2014 CE when a rate of 2.02 mm/yr was attained, which is the fastest, century-scale trend in the ~ 2000-year record. Comparison to existing reconstructions from the Gulf coast of Louisiana and the Atlantic coast of northern Florida reveal similar sea-level histories at all three sites. We explored the influence of compaction and fluvial processes on our reconstruction and concluded that compaction was likely insignificant. Fluvial processes were also likely insignificant, but further proxy evidence is needed to fully test this hypothesis. Our results

Mid- to Late Holocene climate development in Central Asia as revealed from multi-proxy analyses of sediments from Lake Son Kol (Kyrgyzstan)

Science.gov (United States)

Lauterbach, Stefan; Dulski, Peter; Gleixner, Gerd; Hettler-Riedel, Sabine; Mingram, Jens; Plessen, Birgit; Prasad, Sushma; Schwalb, Antje; Schwarz, Anja; Stebich, Martina; Witt, Roman

2013-04-01

A mid-Holocene shift from predominantly wet to significantly drier climate conditions, attributed to the weakening of the Asian summer monsoon (ASM), is documented in numerous palaeoclimate records from the monsoon-influenced parts of Asia, e.g. the Tibetan Plateau and north- and southeastern China. In contrast, Holocene climate development in the arid regions of mid-latitude Central Asia, located north and northwest of the Tibetan Plateau, is less well-constrained but supposed to have been influenced by a complex interaction between the mid-latitude Westerlies and the ASM. Hence, well-dated and highly resolved palaeoclimate records from Central Asia might provide important information about spatio-temporal changes in the regional interplay between Westerlies and ASM and thus aid the understanding of global climate teleconnections. As a part of the project CADY (Central Asian Climate Dynamics), aiming at reconstructing past climatic and hydrological variability in Central Asia, several sediment cores were recovered from alpine Lake Son Kol (41° 48'N, 75° 12'E, 3016 m a. s. l.) in the Central Tian Shan of Kyrgyzstan. A radiocarbon-dated sediment sequence of 154.5 cm length, covering approximately the last 6000 years, was investigated by using a multi-proxy approach, including sedimentological, (bio)geochemical, isotopic and micropalaeontological analyses. Preliminary proxy data indicate hydrologically variable but predominantly wet conditions until ca. 5100 cal. a BP, characterized by the deposition of finely laminated organic-carbonatic sediments. In contrast to monsoonal Asia, where a distinct trend towards drier conditions is observed since the mid-Holocene, the hydrologically variable interval at Lake Son Kol was apparently followed by an only short-term dry episode between ca. 5100 and 4200 cal. a BP. This is characterized by a higher δD of the C29 n-alkanes, probably reflecting increased evapotranspiration. Also pollen, diatom and ostracod data point

Establishing politically feasible water markets: a multi-criteria approach.

Science.gov (United States)

Ballestero, Enrique; Alarcón, Silverio; García-Bernabeu, Ana

2002-08-01

A multiple criteria decision-making (MCDM) model to simulate the establishment of water markets is developed. The environment is an irrigated area governed by a non-profit agency, which is responsible for water production, allocation, and pricing. There is a traditional situation of historical rights, average-cost pricing for water allocation, large quantities of water used, and inefficiency. A market-oriented policy could be implemented by accounting for ecological and political objectives such as saving groundwater and safeguarding historical rights while promoting economic efficiency. In this paper, a problem is solved by compromise programming, a multi-criteria technique based on the principles of Simonian logic. The model is theoretically developed and applied to the Lorca region in Spain near the Mediterranean Sea.

A GIS Approach to Wind,SST(Sea Surface Temperature) and CHL(Chlorophyll) variations in the Caspian Sea

Science.gov (United States)

Mirkhalili, Seyedhamzeh

2016-07-01

Chlorophyll is an extremely important bio-molecule, critical in photosynthesis, which allows plants to absorb energy from light. At the base of the ocean food web are single-celled algae and other plant-like organisms known as Phytoplankton. Like plants on land, Phytoplankton use chlorophyll and other light-harvesting pigments to carry out photosynthesis. Where Phytoplankton grow depends on available sunlight, temperature, and nutrient levels. In this research a GIS Approach using ARCGIS software and QuikSCAT satellite data was applied to visualize WIND,SST(Sea Surface Temperature) and CHL(Chlorophyll) variations in the Caspian Sea.Results indicate that increase in chlorophyll concentration in coastal areas is primarily driven by terrestrial nutrients and does not imply that warmer SST will lead to an increase in chlorophyll concentration and consequently Phytoplankton abundance.

Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region : A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

NARCIS (Netherlands)

Kotthoff, Ulrich; Groeneveld, Jeroen; Ash, Jeanine; Fanget, Anne-Sophie; Krupinski, Nadine Quintana; Peyron, Odile; Stepanova, Anna; Warnock, Jonathan; van Helmond, N.A.G.M.; Passey, Benjamin H.; Clausen, Ole Rono; Bennike, O.; Andrén, Elinor; Granoszewski, Wojciech; Andrén, Thomas; Filipsson, Helena L.; Solveig-Seidenkrantz, M.; Slomp, C.P.; Bauersachs, Thorsten

2017-01-01

Sediment records recovered from the Baltic Sea during Integrated Ocean Drilling Program Expedition 347 provide a unique opportunity to study paleoenvironmental and -climate change in central/northern Europe. Such studies contribute to a better understanding of how environmental parameters change in

Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years.

Science.gov (United States)

Thornalley, David J R; Oppo, Delia W; Ortega, Pablo; Robson, Jon I; Brierley, Chris M; Davis, Renee; Hall, Ian R; Moffa-Sanchez, Paola; Rose, Neil L; Spooner, Peter T; Yashayaev, Igor; Keigwin, Lloyd D

2018-04-01

The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth's climate, redistributing heat and influencing the carbon cycle 1, 2 . The AMOC has been shown to be weakening in recent years 1 ; this decline may reflect decadal-scale variability in convection in the Labrador Sea, but short observational datasets preclude a longer-term perspective on the modern state and variability of Labrador Sea convection and the AMOC 1, 3-5 . Here we provide several lines of palaeo-oceanographic evidence that Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately AD 1850) compared with the preceding 1,500 years. Our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the LIA, or as a more gradual, continued decline over the past 150 years; this ambiguity probably arises from non-AMOC influences on the various proxies or from the different sensitivities of these proxies to individual components of the AMOC. We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA-sourced from melting glaciers and thickened sea ice that developed earlier in the LIA-weakened Labrador Sea convection and the AMOC. The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet 6 . Our results suggest that recent decadal variability in Labrador Sea convection and the AMOC has occurred during an atypical, weak background state. Future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the AMOC weakening described here.

Perbandingan proxy pada linux dan windows untuk mempercepat browsing website

Directory of Open Access Journals (Sweden)

Dafwen Toresa

2017-05-01

Full Text Available AbstrakPada saat ini sangat banyak organisasi, baik pendidikan, pemerintahan,  maupun perusahaan swasta berusaha membatasi akses para pengguna ke internet dengan alasan bandwidth yang dimiliki mulai terasa lambat ketika para penggunanya mulai banyak yang melakukan browsing ke internet. Mempercepat akses browsing menjadi perhatian utama dengan memanfaatkan teknologi Proxy server. Penggunaan proxy server perlu mempertimbangkan sistem operasi pada server dan tool yang digunakan belum diketahui performansi terbaiknya pada sistem operasi apa.  Untuk itu dirasa perlu untuk menganalisis performan Proxy server pada sistem operasi berbeda yaitu Sistem Operasi Linux dengan tools Squid  dan Sistem Operasi Windows dengan tool Winroute. Kajian ini dilakukan untuk mengetahui perbandingan kecepatan browsing dari komputer pengguna (client. Browser yang digunakan di komputer pengguna adalah Mozilla Firefox. Penelitian ini menggunakan 2 komputer klien dengan pengujian masing-masingnya 5 kali pengujian pengaksesan/browsing web yang dituju melalui proxy server. Dari hasil pengujian yang dilakukan, diperoleh kesimpulan bahwa penerapan proxy server di sistem operasi linux dengan tools squid lebih cepat browsing dari klien menggunakan web browser yang sama dan komputer klien yang berbeda dari pada proxy server sistem operasi windows dengan tools winroute.  Kata kunci: Proxy, Bandwidth, Browsing, Squid, Winroute AbstractAt this time very many organizations, both education, government, and private companies try to limit the access of users to the internet on the grounds that the bandwidth owned began to feel slow when the users began to do a lot of browsing to the internet. Speed up browsing access is a major concern by utilizing Proxy server technology. The use of proxy servers need to consider the operating system on the server and the tool used is not yet known the best performance on what operating system. For that it is necessary to analyze Performance Proxy

Starspot variability as an X-ray radiation proxy

Science.gov (United States)

Arkhypov, Oleksiy V.; Khodachenko, Maxim L.; Lammer, Helmut; Güdel, Manuel; Lüftinger, Teresa; Johnstone, Colin P.

2018-05-01

Stellar X-ray emission plays an important role in the study of exoplanets as a proxy for stellar winds and as a basis for the prediction of extreme ultraviolet (EUV) flux, unavailable for direct measurements, which in their turn are important factors for the mass-loss of planetary atmospheres. Unfortunately, the detection thresholds limit the number of stars with the directly measured X-ray fluxes. At the same time, the known connection between the sunspots and X-ray sources allows using of the starspot variability as an accessible proxy for the stellar X-ray emission. To realize this approach, we analysed the light curves of 1729 main-sequence stars with rotation periods 0.5 X-ray to bolometric luminosity ratio Rx. As a result, the regressions for stellar X-ray luminosity Lx(P, Teff) and its related EUV analogue LEUV were obtained for the main-sequence stars. It was shown that these regressions allow prediction of average (over the considered stars) values of log (Lx) and log (LEUV) with typical errors of 0.26 and 0.22 dex, respectively. This, however, does not include the activity variations in particular stars related to their individual magnetic activity cycles.

Isotopic signatures of eelgrass (Zostera marina L.) as bioindicator of anthropogenic nutrient input in the western Baltic Sea

International Nuclear Information System (INIS)

Schubert, Philipp R.; Karez, Rolf; Reusch, Thorsten B.H.; Dierking, Jan

2013-01-01

Highlights: • Anthropogenic nitrogen (N) inputs are a global problem, but difficult to quantify. • We tested the use of eelgrass δ 15 N as proxy of such inputs in the Baltic Sea. • The method revealed distinct spatial patterns in sewage N across a eutrophic bay. • Traditional eutrophication measures corroborated the results from δ 15 N values. • Eelgrass δ 15 N ratios have high potential as proxy of sewage-derived N in the Baltic. -- Abstract: Eutrophication is a global environmental problem. Better management of this threat requires more accurate assessments of anthropogenic nitrogen (N) inputs to coastal systems than can be obtained with traditional measures. Recently, primary producer N isotopic signatures have emerged as useful proxy of such inputs. Here, we demonstrated for the first time the applicability of this method using the widespread eelgrass (Zostera marina) in the highly eutrophic Baltic Sea. Spatial availability of sewage N across a bay with one major sewage outflow predicted by eelgrass δ 15 N was high near and downstream of the outflow compared to upstream, but returned to upstream levels within 4 km downstream from the outfall. General conclusions were corroborated by traditional eutrophication measures, but in contrast to these measures were fully quantitative. Eelgrass N isotope ratios therefore show high potential for coastal screens of eutrophication in the Baltic Sea, and in other areas with eelgrass meadows

The effects of additional black carbon on Arctic sea ice surface albedo: variation with sea ice type and snow cover

OpenAIRE

A. A. Marks; M. D. King

2013-01-01

Black carbon in sea ice will decrease sea ice surface albedo through increased absorption of incident solar radiation, exacerbating sea ice melting. Previous literature has reported different albedo responses to additions of black carbon in sea ice and has not considered how a snow cover may mitigate the effect of black carbon in sea ice. Sea ice is predominately snow covered. Visible light absorption and light scattering coefficients are calculated for a typical first year and multi-y...

Sea level reconstruction: Exploration of methods for combining altimetry with other data to beyond the 20-year altimetric record

DEFF Research Database (Denmark)

Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

2012-01-01

Ocean satellite altimetry has provided global sets of sea level data for the last two decades, allowing determination of spatial patterns in global sea level. For reconstructions going back further than this period, tide gauge data can be used as a proxy for the model. We examine different methods...... to spatial distribution, and tide gauge data are available around the Arctic Ocean, which may be important for a later high-latitude reconstruction....... of combining satellite altimetry and tide gauge data using optimal weighting of tide gauge data, linear regression and EOFs, including automatic quality checks of the tide gauge time series. We attempt to augment the model using various proxies such as climate indices like the NAO and PDO, and investigate...

Analytic hierarchy process-based approach for selecting a Pareto-optimal solution of a multi-objective, multi-site supply-chain planning problem

Science.gov (United States)

Ayadi, Omar; Felfel, Houssem; Masmoudi, Faouzi

2017-07-01

The current manufacturing environment has changed from traditional single-plant to multi-site supply chain where multiple plants are serving customer demands. In this article, a tactical multi-objective, multi-period, multi-product, multi-site supply-chain planning problem is proposed. A corresponding optimization model aiming to simultaneously minimize the total cost, maximize product quality and maximize the customer satisfaction demand level is developed. The proposed solution approach yields to a front of Pareto-optimal solutions that represents the trade-offs among the different objectives. Subsequently, the analytic hierarchy process method is applied to select the best Pareto-optimal solution according to the preferences of the decision maker. The robustness of the solutions and the proposed approach are discussed based on a sensitivity analysis and an application to a real case from the textile and apparel industry.

An approach to multi-attribute utility analysis under parametric uncertainty

International Nuclear Information System (INIS)

Kelly, M.; Thorne, M.C.

2001-01-01

The techniques of cost-benefit analysis and multi-attribute analysis provide a useful basis for informing decisions in situations where a number of potentially conflicting opinions or interests need to be considered, and where there are a number of possible decisions that could be adopted. When the input data to such decision-making processes are uniquely specified, cost-benefit analysis and multi-attribute utility analysis provide unambiguous guidance on the preferred decision option. However, when the data are not uniquely specified, application and interpretation of these techniques is more complex. Herein, an approach to multi-attribute utility analysis (and hence, as a special case, cost-benefit analysis) when input data are subject to parametric uncertainty is presented. The approach is based on the use of a Monte Carlo technique, and has recently been applied to options for the remediation of former uranium mining liabilities in a number of Central and Eastern European States

Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea

Science.gov (United States)

Kuffner, Ilsa B.; Roberts, Kelsey E.; Flannery, Jennifer A.; Morrison, Jennifer M.; Richey, Julie N.

2017-01-01

Massive corals provide a useful archive of environmental variability, but careful testing of geochemical proxies in corals is necessary to validate the relationship between each proxy and environmental parameter throughout the full range of conditions experienced by the recording organisms. Here we use samples from a coral-growth study to test the hypothesis that Sr/Ca in the coral Siderastrea siderea accurately records sea-surface temperature (SST) in the subtropics (Florida, USA) along 350 km of reef tract. We test calcification rate, measured via buoyant weight, and linear extension (LE) rate, estimated with Alizarin Red-S staining, as predictors of variance in the Sr/Ca records of 39 individual S. siderea corals grown at four outer-reef locations next to in-situ temperature loggers during two, year-long periods. We found that corals with calcification rates corals that passed this quality control step, the Sr/Ca-SST proxy performed well in estimating mean annual temperature across three sites spanning 350 km of the Florida reef tract. However, there was some evidence that extreme temperature stress in 2010 (cold snap) and 2011 (SST above coral-bleaching threshold) may have caused the corals not to record the temperature extremes. Known stress events could be avoided during modern calibrations of paleoproxies.Plain Language SummaryCoral skeletons are used to decipher past environmental conditions in the ocean because they live for centuries and produce annual growth bands much like tree rings. Along with measuring coral growth rates in the past, coral skeletons can be chemically sampled to get even more detailed information, like past seawater temperatures. In this study we tested the validity of the strontium-to-calcium (Sr/Ca) temperature proxy in the Massive Starlet Coral (Siderastrea siderea) by sampling 39 corals that were grown in the ocean right next to instruments recording underwater temperature. We found that, as long as corals with very slow growth

Processes controlling trace element geochemistry of Arabian Sea sediments during the last 25,000 years

Science.gov (United States)

Sirocko, Frank; Garbe-Schönberg, Dieter; Devey, Colin

2000-11-01

Thirty seven deep-sea sediment cores from the Arabian Sea were studied geochemically (49 major and trace elements) for four time slices during the Holocene and the last glacial, and in one high sedimentation rate core (century scale resolution) to detect tracers of past variations in the intensity of the atmospheric monsoon circulation and its hydrographic expression in the ocean surface. This geochemical multi-tracer approach, coupled with additional information on the grain size composition of the clastic fraction, the bulk carbonate and biogenic opal contents makes it possible to characterize the sedimentological regime in detail. Sediments characterized by a specific elemental composition (enrichment) originated from the following sources: river suspensions from the Tapti and Narbada, draining the Indian Deccan traps (Ti, Sr); Indus sediments and dust from Rajasthan and Pakistan (Rb, Cs); dust from Iran and the Persian Gulf (Al, Cr); dust from central Arabia (Mg); dust from East Africa and the Red Sea (Zr/Hf, Ti/Al). C org, Cd, Zn, Ba, Pb, U, and the HREE are associated with the intensity of upwelling in the western Arabian Sea, but only those patterns that are consistently reproduced by all of these elements can be directly linked with the intensity of the southwest monsoon. Relying on information from a single element can be misleading, as each element is affected by various other processes than upwelling intensity and nutrient content of surface water alone. The application of the geochemical multi-tracer approach indicates that the intensity of the southwest monsoon was low during the LGM, declined to a minimum from 15,000-13,000 14C year BP, intensified slightly at the end of this interval, was almost stable during the Bölling, Alleröd and the Younger Dryas, but then intensified in two abrupt successions at the end of the Younger Dryas (9900 14C year BP) and especially in a second event during the early Holocene (8800 14C year BP). Dust discharge by

New evidence for "far-field" Holocene sea level oscillations and links to global climate records

Science.gov (United States)

Leonard, N. D.; Welsh, K. J.; Clark, T. R.; Feng, Y.-x.; Pandolfi, J. M.; Zhao, J.-x.

2018-04-01

Rising sea level in the coming century is of significant concern, yet predicting relative sea level change in response to eustatic sea level variability is complex. Potential analogues are provided by the recent geological past but, until recently, many sea level reconstructions have been limited to millennial scale interpretations due to age uncertainties and paucity in proxy derived records. Here we present a sea level history for the tectonically stable "far-field" Great Barrier Reef, Australia, derived from 94 high precision uranium-thorium dates of sub-fossil coral microatolls. Our results provide evidence for at least two periods of relative sea level instability during the Holocene. These sea level oscillations are broadly synchronous with Indo-Pacific negative sea surface temperature anomalies, rapid global cooling events and glacial advances. We propose that the pace and magnitude of these oscillations are suggestive of eustatic/thermosteric processes operating in conjunction with regional climatic controls.

Regulated open multi-agent systems (ROMAS) a multi-agent approach for designing normative open systems

CERN Document Server

Garcia, Emilia; Botti, Vicente

2015-01-01

Addressing the open problem of engineering normative open systems using the multi-agent paradigm, normative open systems are explained as systems in which heterogeneous and autonomous entities and institutions coexist in a complex social and legal framework that can evolve to address the different and often conflicting objectives of the many stakeholders involved. Presenting  a software engineering approach which covers both the analysis and design of these kinds of systems, and which deals with the open issues in the area, ROMAS (Regulated Open Multi-Agent Systems) defines a specific multi-agent architecture, meta-model, methodology and CASE tool. This CASE tool is based on Model-Driven technology and integrates the graphical design with the formal verification of some properties of these systems by means of model checking techniques. Utilizing tables to enhance reader insights into the most important requirements for designing normative open multi-agent systems, the book also provides a detailed and easy t...

Appraising timing response of paleoenvironmental proxies to the Bond cycle in the western Mediterranean over the last 20 kyr

Science.gov (United States)

Rodrigo-Gámiz, Marta; Martínez-Ruiz, Francisca; Rodríguez-Tovar, Francisco J.; Pardo-Igúzquiza, Eulogio; Ortega-Huertas, Miguel

2018-04-01

The timing of climate responses to the Bond cycle is investigated in the western Mediterranean. Periodicities had been previously reported in a marine sediment record from this region spanning the last 20 kyr, and registered by diverse paleoenvironmental proxies, in particular those associated with terrigenous input, redox conditions, productivity, sea surface temperature (SST) and salinity. Further cross-spectral analyses on these time series reveal leads-lags in the 1400 year climate cycle. Considering as reference a terrigenous input proxy (the K/Al ratio), all the paleoenvironmental proxies displayed time shifts varying from ca. 700 year to ca. 350 year. SST and salinity variations show a first leaded response with the inflow of cold and less salty Atlantic waters. Followed by a time lead of 525 year, progresively arid conditions with an increase of eolian dust transport to the area, given by the Zr/Al signal, are observed. The intensification of dust transport could have triggered a latest biological response, lead by 350 year, with an increase of productivity, as suggested by the Ba/Al ratio. Lastly changes in the Mediterranean thermohaline circulation, indicated by a selected redox proxy (the U/Th ratio), are observed. These results support that the oceanic response triggered the atmospheric response to the Bond cycle in the western Mediterranean. Changes in the North Atlantic Oscillation mode and in the Inter-Tropical Convergence Zone migrations with variations in the monsoon activity or Saharan winds system, are considered as main forcing mechanisms, with a complex relationship of the involved phenomena.

What is at stake in multi-scale approaches

International Nuclear Information System (INIS)

Jamet, Didier

2008-01-01

Full text of publication follows: Multi-scale approaches amount to analyzing physical phenomena at small space and time scales in order to model their effects at larger scales. This approach is very general in physics and engineering; one of the best examples of success of this approach is certainly statistical physics that allows to recover classical thermodynamics and to determine the limits of application of classical thermodynamics. Getting access to small scale information aims at reducing the models' uncertainty but it has a cost: fine scale models may be more complex than larger scale models and their resolution may require the development of specific and possibly expensive methods, numerical simulation techniques and experiments. For instance, in applications related to nuclear engineering, the application of computational fluid dynamics instead of cruder models is a formidable engineering challenge because it requires resorting to high performance computing. Likewise, in two-phase flow modeling, the techniques of direct numerical simulation, where all the interfaces are tracked individually and where all turbulence scales are captured, are getting mature enough to be considered for averaged modeling purposes. However, resolving small scale problems is a necessary step but it is not sufficient in a multi-scale approach. An important modeling challenge is to determine how to treat small scale data in order to get relevant information for larger scale models. For some applications, such as single-phase turbulence or transfers in porous media, this up-scaling approach is known and is now used rather routinely. However, in two-phase flow modeling, the up-scaling approach is not as mature and specific issues must be addressed that raise fundamental questions. This will be discussed and illustrated. (author)

Detrital phosphorus as a proxy of flooding events in the Changjiang River Basin

International Nuclear Information System (INIS)

Meng, Jia; Yao, Peng; Bianchi, Thomas S.; Li, Dong; Zhao, Bin; Xu, Bochao; Yu, Zhigang

2015-01-01

In this study, sediment grain size (MGS), specific surface area (SSA), total organic carbon (TOC) contents, C/N molar ratios, stable carbon isotope, and P species in a sediment core, collected from the East China Sea (ECS) inner-shelf were measured to explore the applicability of detrital phosphorus (De-P) as a potential indicator of past flooding events in the Changjiang River Basin (CRB). In particular, we examined the linkages between the evolution of floods with regional climate changes and anthropogenic activities in the CRB. Peaks of De-P concentrations in sediments corresponded well with the worst flooding events of the CRB over the past two centuries (e.g., 1850s, 1860s, 1900s, 1920s, 1950s, 1980s, and 2000s). Moreover, De-P also corresponded well with the extreme hypoxic events in 1981 and 1998 in the Changjiang Estuary as indicated by Mo/Al ratios, indicating potential linkages between De-P as a flooding proxy to flood-induced hypoxia events in this region. In addition, a robust relationship was found among De-P, the floods in 1950s, 1980s, and 2000s of the CRB, the intensive El Niño-Southern Oscillation (ENSO), the abnormally weak East Asian Summer Monsoon (EASM) and the warm phase of Pacific Decadal Oscillation (PDO), suggesting that De-P also provided insights to linkages between regional climate change and flooding events in this region. - Highlights: • De-P was used to track past floods in the Changjiang River Basin (CRB). • De-P may serve as a proxy for flood-induced hypoxia events in the Changjiang Estuary. • De-P may be a proxy for examining linkages between floods and climatic drivers

Detrital phosphorus as a proxy of flooding events in the Changjiang River Basin

Energy Technology Data Exchange (ETDEWEB)

Meng, Jia [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Yao, Peng, E-mail: yaopeng@mail.ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); Qingdao Collaborative Innovation Center of Marine Science and Technology, Qingdao 266100 (China); Institute of Marine Organic Geochemistry, Ocean University of China, Qingdao 266100 (China); Bianchi, Thomas S. [Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120 (United States); Li, Dong; Zhao, Bin; Xu, Bochao [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Yu, Zhigang [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); Institute of Marine Organic Geochemistry, Ocean University of China, Qingdao 266100 (China)

2015-06-01

In this study, sediment grain size (MGS), specific surface area (SSA), total organic carbon (TOC) contents, C/N molar ratios, stable carbon isotope, and P species in a sediment core, collected from the East China Sea (ECS) inner-shelf were measured to explore the applicability of detrital phosphorus (De-P) as a potential indicator of past flooding events in the Changjiang River Basin (CRB). In particular, we examined the linkages between the evolution of floods with regional climate changes and anthropogenic activities in the CRB. Peaks of De-P concentrations in sediments corresponded well with the worst flooding events of the CRB over the past two centuries (e.g., 1850s, 1860s, 1900s, 1920s, 1950s, 1980s, and 2000s). Moreover, De-P also corresponded well with the extreme hypoxic events in 1981 and 1998 in the Changjiang Estuary as indicated by Mo/Al ratios, indicating potential linkages between De-P as a flooding proxy to flood-induced hypoxia events in this region. In addition, a robust relationship was found among De-P, the floods in 1950s, 1980s, and 2000s of the CRB, the intensive El Niño-Southern Oscillation (ENSO), the abnormally weak East Asian Summer Monsoon (EASM) and the warm phase of Pacific Decadal Oscillation (PDO), suggesting that De-P also provided insights to linkages between regional climate change and flooding events in this region. - Highlights: • De-P was used to track past floods in the Changjiang River Basin (CRB). • De-P may serve as a proxy for flood-induced hypoxia events in the Changjiang Estuary. • De-P may be a proxy for examining linkages between floods and climatic drivers.

A multi-objective approach for developing national energy efficiency plans

International Nuclear Information System (INIS)

Haydt, Gustavo; Leal, Vítor; Dias, Luís

2014-01-01

This paper proposes a new approach to deal with the problem of building national energy efficiency (EE) plans, considering multiple objectives instead of only energy savings. The objectives considered are minimizing the influence of energy use on climate change, minimizing the financial risk from the investment, maximizing the security of energy supply, minimizing investment costs, minimizing the impacts of building new power plants and transmission infrastructures, and maximizing the local air quality. These were identified through literature review and interaction with real decision makers. A database of measures is established, from which millions of potential EE plans can be built by combining measures and their respective degree of implementation. Finally, a hybrid multi-objective and multi-criteria decision analysis (MCDA) model is proposed to search and select the EE plans that best match the decision makers’ preferences. An illustration of the working mode and the type of results obtained from this novel hybrid model is provided through an application to Portugal. For each of five decision perspectives a wide range of potential best plans were identified. These wide ranges show the relevance of introducing multi-objective analysis in a comprehensive search space as a tool to inform decisions about national EE plans. - Highlights: • A multiple objective approach to aid the choice of national energy efficiency plans. • A hybrid multi-objective MCDA model is proposed to search among the possible plans. • The model identified relevant plans according to five different idealized DMs. • The approach is tested with Portugal

Analisis Algoritma Pergantian Cache Pada Proxy Web Server Internet Dengan Simulasi

OpenAIRE

Nurwarsito, Heru

2007-01-01

Pertumbuhan jumlah client internet dari waktu ke waktu terus bertambah, maka respon akses internet menjadi semakin lambat. Untuk membantu kecepatan akses tersebut maka diperlukan cache pada Proxy Server. Penelitian ini bertujuan untuk menganalisis performansi Proxy Server pada Jaringan Internet terhadap penggunaan algoritma pergantian cache-nya.Analisis Algoritma Pergantian Cache Pada Proxy Server didesain dengan metoda pemodelan simulasi jaringan internet yang terdiri dari Web server, Proxy ...

Gradient-based model calibration with proxy-model assistance

Science.gov (United States)

Burrows, Wesley; Doherty, John

2016-02-01

Use of a proxy model in gradient-based calibration and uncertainty analysis of a complex groundwater model with large run times and problematic numerical behaviour is described. The methodology is general, and can be used with models of all types. The proxy model is based on a series of analytical functions that link all model outputs used in the calibration process to all parameters requiring estimation. In enforcing history-matching constraints during the calibration and post-calibration uncertainty analysis processes, the proxy model is run for the purposes of populating the Jacobian matrix, while the original model is run when testing parameter upgrades; the latter process is readily parallelized. Use of a proxy model in this fashion dramatically reduces the computational burden of complex model calibration and uncertainty analysis. At the same time, the effect of model numerical misbehaviour on calculation of local gradients is mitigated, this allowing access to the benefits of gradient-based analysis where lack of integrity in finite-difference derivatives calculation would otherwise have impeded such access. Construction of a proxy model, and its subsequent use in calibration of a complex model, and in analysing the uncertainties of predictions made by that model, is implemented in the PEST suite.

Data and Dynamics Driven Approaches for Modelling and Forecasting the Red Sea Chlorophyll

KAUST Repository

Dreano, Denis

2017-05-31

Phytoplankton is at the basis of the marine food chain and therefore play a fundamental role in the ocean ecosystem. However, the large-scale phytoplankton dynamics of the Red Sea are not well understood yet, mainly due to the lack of historical in situ measurements. As a result, our knowledge in this area relies mostly on remotely-sensed observations and large-scale numerical marine ecosystem models. Models are very useful to identify the mechanisms driving the variations in chlorophyll concentration and have practical applications for fisheries operation and harmful algae blooms monitoring. Modelling approaches can be divided between physics- driven (dynamical) approaches, and data-driven (statistical) approaches. Dynamical models are based on a set of differential equations representing the transfer of energy and matter between different subsets of the biota, whereas statistical models identify relationships between variables based on statistical relations within the available data. The goal of this thesis is to develop, implement and test novel dynamical and statistical modelling approaches for studying and forecasting the variability of chlorophyll concentration in the Red Sea. These new models are evaluated in term of their ability to efficiently forecast and explain the regional chlorophyll variability. We also propose innovative synergistic strategies to combine data- and physics-driven approaches to further enhance chlorophyll forecasting capabilities and efficiency.

Development of Oil Spill Monitoring System for the Black Sea, Caspian Sea and the Barents/Kara Seas (DEMOSS)

Science.gov (United States)

Sandven, Stein; Kudriavtsev, Vladimir; Malinovsky, Vladimir; Stanovoy, Vladimir

2008-01-01

DEMOSS will develop and demonstrate elements of a marine oil spill detection and prediction system based on satellite Synthetic Aperture Radar (SAR) and other space data. In addition, models for prediction of sea surface pollution drift will be developed and tested. The project implements field experiments to study the effect of artificial crude oil and oil derivatives films on short wind waves and multi-frequency (Ka-, Ku-, X-, and C-band) dual polarization radar backscatter power and Doppler shift at different wind and wave conditions. On the basis of these and other available experimental data, the present model of short wind waves and radar scattering will be improved and tested.A new approach for detection and quantification of the oil slicks/spills in satellite SAR images is developed that can discriminate human oil spills from biogenic slicks and look-alikes in the SAR images. New SAR images are obtained in coordination with the field experiments to test the detection algorithm. Satellite SAR images from archives as well as from new acquisitions will be analyzed for the Black/Caspian/Kara/Barents seas to investigate oil slicks/spills occurrence statistics.A model for oil spills/slicks transport and evolution is developed and tested in ice-infested arctic seas, including the Caspian Sea. Case studies using the model will be conducted to simulate drift and evolution of oil spill events observed in SAR images. The results of the project will be disseminated via scientific publications and by demonstration to users and agencies working with marine monitoring. The project lasts for two years (2007 - 2009) and is funded under INTAS Thematic Call with ESA 2006.

Multi-Layered Stratification in the Baltic Sea: Insight from a Modeling Study with Reference to Environmental Conditions

Directory of Open Access Journals (Sweden)

Bijan Dargahi

2017-01-01

Full Text Available The hydrodynamic and transport characteristics of the Baltic Sea in the period 2000–2009 were studied using a fully calibrated and validated 3D hydrodynamic model with a horizontal resolution of 4.8 km. This study provided new insight into the type and dynamics of vertical structure in the Baltic Sea, not considered in previous studies. Thermal and salinity stratification are both addressed, with a focus on the structural properties of the layers. The detection of cooler regions (dicothermal within the layer structure is an important finding. The detailed investigation of thermal stratification for a 10-year period (i.e., 2000–2009 revealed some new features. A multilayered structure that contains several thermocline and dicothermal layers was identified from this study. Statistical analysis of the simulation results made it possible to derive the mean thermal stratification properties, expressed as mean temperatures and the normalized layer thicknesses. The three-layered model proposed by previous investigators appears to be valid only during the winter periods; for other periods, a multi-layered structure with more than five layers has been identified during this investigation. This study provides detailed insight into thermal and salinity stratification in the Baltic Sea during a recent decade that can be used as a basis for diverse environmental assessments. It extends previous studies on stratification in the Baltic Sea regarding both the extent and the nature of stratification.

Benthic foraminifera cultured over a large salinity gradient: first results and comparison with field data from the Baltic Sea.

Science.gov (United States)

Groeneveld, Jeroen; Filipsson, Helena L.; Austin, William E. N.; Darling, Kate; Quintana Krupinski, Nadine B.

2015-04-01

Some of the most significant challenges in paleoclimate research arise from the need to both understand and reduce the uncertainty associated with proxy methods for climate reconstructions. This is especially important for shelf and coastal environments where increasing numbers of high-resolution paleorecords are being generated. These challenges are further highlighted in connection with ECORD/IODP Expedition 347: Baltic Sea Paleoenvironments. This large-scale drilling operation took place in the Baltic Sea region during the autumn of 2013. At this time, there is a pressing need for proxy calibrations directly targeted at the brackish Baltic environment. Within the CONTEMPORARY project we are investigating different temperature and salinity proxy variables through a combination of field- and culture-based benthic foraminiferal samples, together with genetic characterization (genotyping) of the morphospecies. We have completed two field campaigns where we collected (living) foraminifera and water samples at several sites, ranging from fully marine to low salinity conditions. The core-top foraminifera have been analysed for trace metal/Ca, stable oxygen and carbon isotopes, and faunal composition. Living foraminifera collected from the sediment-water interface were cultured in sea water in two long-term experiments at different temperatures (5°C and 10°C) and at three different salinities (15, 25, and 35). The first experiment yielded a large number of reproduced and experimentally-grown Elphidium specimens. The second experiment resulted in growth but no reproduction. We will provide a summary of the experimentally grown material and discuss the challenges of generating new proxy calibrations for foraminiferal shell geochemistry in the Baltic Sea. Furthermore, specimens of Elphidium and Ammonia, found at two sampling sites (Anholt, Kattegat and Hanöbay) with differing salinities, were genotyped and the results indicate that the same genotype of Elphidium is

Measuring the sustainability of a natural system by using multi-criteria distance function methods: Some critical issues.

Science.gov (United States)

Diaz-Balteiro, L; Belavenutti, P; Ezquerro, M; González-Pachón, J; Ribeiro Nobre, S; Romero, C

2018-05-15

There is an important body of literature using multi-criteria distance function methods for the aggregation of a battery of sustainability indicators in order to obtain a composite index. This index is considered to be a proxy of the sustainability goodness of a natural system. Although this approach has been profusely used in the literature, it is not exempt from difficulties and potential pitfalls. Thus, in this paper, a significant number of critical issues have been identified showing different procedures capable of avoiding, or at least of mitigating, the inherent potential pitfalls associated with each one. The recommendations made in the paper could increase the theoretical soundness of the multi-criteria distance function methods when this type of approach is applied in the sustainability field, thus increasing the accuracy and realism of the sustainability measurements obtained. Copyright © 2018 Elsevier Ltd. All rights reserved.

Micro-CT of sea urchin ossicles supplemented with microbeam diffraction

Science.gov (United States)

Stock, Stuart R.; Ignatiev, Konstantin I.; Veis, Arthur; De Carlo, Francesco; Almer, J. D.

2004-10-01

Sea urchins employ as wide a range of composite reinforcement strategies as are seen in engineering composites. Besides tailoring reinforcement morphology and alignment to the functional demands of position, solid solution strengthening (high Mg calcite), inclusion toughening (macromolecules), functional gradients in mineral reinforcement morphology, composition and dimensions and mineral interface tailoring are other tactics important to achieving high toughness and high strength in sea urchin teeth. Teeth from different echinoid families illustrate combinations of reinforcement parameters and toughening mechanisms providing good functionality, a virtual probe of the available design space. This paper focuses on a multi-mode x-ray investigation of sea urchin teeth studied on scales approaching 1 μm in millimeter-sized samples, in particular mapping 3-D microarchitecture with synchrotron and laboratory microCT and mapping Ca1-xMgxCO3 crystal composition x and microstrain and crystallite size via microbeam diffraction.

Late Pliocene/Pleistocene changes in Arctic sea-ice cover: Biomarker and dinoflagellate records from Fram Strait/Yermak Plateau (ODP Sites 911 and 912)

Science.gov (United States)

Stein, Ruediger; Fahl, Kirsten; Matthiessen, Jens

2014-05-01

Sea ice is a critical component in the (global) climate system that contributes to changes in the Earth's albedo (heat reduction) and biological processes (primary productivity), as well as deep-water formation, a driving mechanism for global thermohaline circulation. Thus, understanding the processes controlling Arctic sea ice variability is of overall interest and significance. Recently, a novel and promising biomarker proxy for reconstruction of Arctic sea-ice conditions was developed and is based on the determination of a highly-branched isoprenoid with 25 carbons (IP25; Belt et al., 2007; PIP25 when combined with open-water phytoplankton biomarkers; Müller et al., 2011). Here, we present biomarker data from Ocean Drilling Program (ODP) Sites 911 and 912, recovered from the southern Yermak Plateau and representing information of sea-ice variability, changes in primary productivity and terrigenous input during the last about 3.5 Ma. As Sites 911 and 912 are close to the modern sea-ice edge, their sedimentary records seem to be optimal for studying past variability in sea-ice coverage and testing the applicability of IP25 and PIP25 in older sedimentary sequences. In general, our biomarker records correlate quite well with other climate and sea-ice proxies (e.g., dinoflagellates, IRD, etc.). The main results can be summarized as follows: (1) The novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering at least the last 3.5 Ma, i.e., the time interval including the onset (intensification) of major Northern Hemisphere Glaciation (NHG). (2) These data indicate that sea ice of variable extent was present in the Fram Strait/southern Yermak Plateau area during most of the time period under investigation. (3) Elevated IP25/PIP25 values indicative for an extended spring sea-ice cover, already occurred between 3.6 and 2.9 Ma, i.e., prior to the onset of major NHG. This may suggest that sea-ice and related albedo effects might

Developing a proxy version of the Adult social care outcome toolkit (ASCOT).

Science.gov (United States)

Rand, Stacey; Caiels, James; Collins, Grace; Forder, Julien

2017-05-19

Social care-related quality of life is a key outcome indicator used in the evaluation of social care interventions and policy. It is not, however, always possible to collect quality of life data by self-report even with adaptations for people with cognitive or communication impairments. A new proxy-report version of the Adult Social Care Outcomes Toolkit (ASCOT) measure of social care-related quality of life was developed to address the issues of wider inclusion of people with cognitive or communication difficulties who may otherwise be systematically excluded. The development of the proxy-report ASCOT questionnaire was informed by literature review and earlier work that identified the key issues and challenges associated with proxy-reported outcomes. To evaluate the acceptability and content validity of the ASCOT-Proxy, qualitative cognitive interviews were conducted with unpaid carers or care workers of people with cognitive or communication impairments. The proxy respondents were invited to 'think aloud' while completing the questionnaire. Follow-up probes were asked to elicit further detail of the respondent's comprehension of the format, layout and content of each item and also how they weighed up the options to formulate a response. A total of 25 unpaid carers and care workers participated in three iterative rounds of cognitive interviews. The findings indicate that the items were well-understood and the concepts were consistent with the item definitions for the standard self-completion version of ASCOT with minor modifications to the draft ASCOT-Proxy. The ASCOT-Proxy allows respondents to rate the proxy-proxy and proxy-patient perspectives, which improved the acceptability of proxy report. A new proxy-report version of ASCOT was developed with evidence of its qualitative content validity and acceptability. The ASCOT-Proxy is ready for empirical testing of its suitability for data collection as a self-completion and/or interview questionnaire, and also

Variation of paleo-productivity and terrigenous input in the eastern Arabian Sea during the past 100 ka

Digital Repository Service at National Institute of Oceanography (India)

Ishfaq, A.M.; Pattan, J.N.; Matta, V.M.; Banakar, V.K.

A 4.1m long sediment core from the eastern Arabian Sea is studied using multiple geochemical proxies to understand the variation of productivity and terrigenous matter supply during the past 100 ka. The temporal variation in element concentration...

Advances in Alkenone Paleotemperature Proxies: Analytical Methods, Novel Structures and Haptophyte Species, Biosynthesis, New indices and Ecological Aspects

Science.gov (United States)

Huang, Y.; Longo, W. M.; Zheng, Y.; Richter, N.; Dillon, J. T.; Theroux, S.; D'Andrea, W. J.; Toney, J. L.; Wang, L.; Amaral-Zettler, L. A.

2017-12-01

Alkenones are mature, well-established paleo-sea surface temperature proxies that have been widely applied for more than three decades. However, recent advances across a broad range of alkenone-related topics at Brown University are inviting new paleoclimate and paleo-environmental applications for these classic biomarkers. In this presentation, I will summarize our progress in the following areas: (1) Discovery of a freshwater alkenone-producing haptophyte species and structural elucidation of novel alkenone structures unique to the species, performing in-situ temperature calibrations, and classifying alkenone-producing haptophytes into three groups based on molecular ecological approaches (with the new species belonging to Group I Isochrysidales); (2) A global survey of Group I haptophyte distributions and environmental conditions favoring the presence of this alga, as well as examples of using Group I alkenones for paleotemperature reconstructions; (3) New gas chromatographic columns that allow unprecedented resolution of alkenones and alkenoates and associated structural isomers, and development of a new suite of paleotemperature and paleoenvironmental proxies; (4) A new liquid chromatographic separation technique that allows efficient cleanup of alkenones and alkenoates (without the need for saponification) for subsequent coelution-free gas chromatographic analysis; (5) Novel structural features revealed by new analytical methods that now allow a comprehensive re-assessment of taxonomic features of various haptophyte species, with principal component analysis capable of fully resolving species biomarker distributions; (6) Development of UK37 double prime (UK37'') for Group II haptophytes (e.g., those occurring in saline lakes and estuaries), that differs from the traditional unsaturation indices used for SST reconstructions; (7) New assessment of how mixed inputs from different alkenone groups may affect SST reconstructions in marginal ocean environments and

Hydroclimate variability in Scandinavia over the last millennium - insights from a climate model-proxy data comparison

Science.gov (United States)

Seftigen, Kristina; Goosse, Hugues; Klein, Francois; Chen, Deliang

2017-12-01

The integration of climate proxy information with general circulation model (GCM) results offers considerable potential for deriving greater understanding of the mechanisms underlying climate variability, as well as unique opportunities for out-of-sample evaluations of model performance. In this study, we combine insights from a new tree-ring hydroclimate reconstruction from Scandinavia with projections from a suite of forced transient simulations of the last millennium and historical intervals from the CMIP5 and PMIP3 archives. Model simulations and proxy reconstruction data are found to broadly agree on the modes of atmospheric variability that produce droughts-pluvials in the region. Despite these dynamical similarities, large differences between simulated and reconstructed hydroclimate time series remain. We find that the GCM-simulated multi-decadal and/or longer hydroclimate variability is systematically smaller than the proxy-based estimates, whereas the dominance of GCM-simulated high-frequency components of variability is not reflected in the proxy record. Furthermore, the paleoclimate evidence indicates in-phase coherencies between regional hydroclimate and temperature on decadal timescales, i.e., sustained wet periods have often been concurrent with warm periods and vice versa. The CMIP5-PMIP3 archive suggests, however, out-of-phase coherencies between the two variables in the last millennium. The lack of adequate understanding of mechanisms linking temperature and moisture supply on longer timescales has serious implications for attribution and prediction of regional hydroclimate changes. Our findings stress the need for further paleoclimate data-model intercomparison efforts to expand our understanding of the dynamics of hydroclimate variability and change, to enhance our ability to evaluate climate models, and to provide a more comprehensive view of future drought and pluvial risks.

Deep-Sea Microbes: Linking Biogeochemical Rates to -Omics Approaches

Science.gov (United States)

Herndl, G. J.; Sintes, E.; Bayer, B.; Bergauer, K.; Amano, C.; Hansman, R.; Garcia, J.; Reinthaler, T.

2016-02-01

Over the past decade substantial progress has been made in determining deep ocean microbial activity and resolving some of the enigmas in understanding the deep ocean carbon flux. Also, metagenomics approaches have shed light onto the dark ocean's microbes but linking -omics approaches to biogeochemical rate measurements are generally rare in microbial oceanography and even more so for the deep ocean. In this presentation, we will show by combining metagenomics, -proteomics and biogeochemical rate measurements on the bulk and single-cell level that deep-sea microbes exhibit characteristics of generalists with a large genome repertoire, versatile in utilizing substrate as revealed by metaproteomics. This is in striking contrast with the apparently rather uniform dissolved organic matter pool in the deep ocean. Combining the different -omics approaches with metabolic rate measurements, we will highlight some major inconsistencies and enigmas in our understanding of the carbon cycling and microbial food web structure in the dark ocean.

Heat and mass transfer intensification and shape optimization a multi-scale approach

CERN Document Server

2013-01-01

Is the heat and mass transfer intensification defined as a new paradigm of process engineering, or is it just a common and old idea, renamed and given the current taste? Where might intensification occur? How to achieve intensification? How the shape optimization of thermal and fluidic devices leads to intensified heat and mass transfers? To answer these questions, Heat & Mass Transfer Intensification and Shape Optimization: A Multi-scale Approach clarifies  the definition of the intensification by highlighting the potential role of the multi-scale structures, the specific interfacial area, the distribution of driving force, the modes of energy supply and the temporal aspects of processes.   A reflection on the methods of process intensification or heat and mass transfer enhancement in multi-scale structures is provided, including porous media, heat exchangers, fluid distributors, mixers and reactors. A multi-scale approach to achieve intensification and shape optimization is developed and clearly expla...

Multi-criteria decision making approaches for green supply chains

NARCIS (Netherlands)

Banasik, Aleksander; Bloemhof-Ruwaard, Jacqueline M.; Kanellopoulos, Argyris; Claassen, G.D.H.; Vorst, van der Jack G.A.J.

2016-01-01

Designing Green Supply Chains (GSCs) requires complex decision-support models that can deal with multiple dimensions of sustainability while taking into account specific characteristics of products and their supply chain. Multi-Criteria Decision Making (MCDM) approaches can be used to quantify

Proxy assessment of patients before and after radiotherapy for brain metastases. Results of a prospective study using the DEGRO brain module

International Nuclear Information System (INIS)

Steinmann, D.; Vordermark, D.; Geinitz, H.; Aschoff, R.; Bayerl, A.; Gerstein, J.; Hipp, M.; Schaefer, C.; Oorschot, B. van; Wypior, H.J.

2013-01-01

Purpose: Proxies of patients with poor performance status could give useful information about the patients' quality of life (QoL). We applied a newly developed questionnaire in a prospective QoL study of patients undergoing radiotherapy for brain metastases in order to make the first move to validate this instrument, and we compared the results with scores obtained using validated patient-completed instruments. Materials and methods: From January 2007 to June 2010, 166 patients with previously untreated brain metastases were recruited at 14 centers in Germany and Austria. The EORTC-QLQ-C15-PAL and the brain module BN20 were used to assess QoL in patients at the start of treatment and 3 months later. At the same time points, 141 of their proxies estimated the QoL with the new DEGRO brain module (DBM), a ten-item questionnaire rating the general condition as well as functions and impairment by symptoms in areas relevant to patients with brain metastases. Results: At 3 months, 85 of 141 patients (60%) with initial response by a proxy were alive. Sixty-seven of these patients (79% of 3-month survivors) and 65 proxies completed the second set of questionnaires. After 3 months, QoL significantly deteriorated in all items of proxy-assessed QoL except headache. Correlations between self-assessed and proxy-assessed QoL were high in single items such as nausea, headache, and fatigue. Conclusions: The high correlation between self-assessment and proxy ratings as well as a similar change over time for both approaches suggest that in patients with brain metastases, proxy assessment using the DBM questionnaire can be an alternative approach to obtaining QoL data when patients are unable to complete questionnaires themselves. Our self-constructed and first applied DBM is the only highly specific instrument for patients with brain metastases, but further tests are needed for its final validation. (orig.)

Ice-sheet modelling characteristics in sea-level-based temperature reconstructions over the last glacial cycle

NARCIS (Netherlands)

Wilschut, F.; Bintanja, R.; van de Wal, R.S.W.

2006-01-01

A widely used method for investigating palaeotemperatures is to analyze local proxy records (e.g. ice cores or deep-sea sediment cores). The interpretation of these records is often not straightforward, and global or hemispheric means cannot be deduced from local estimates because of large spatial

Using Direct Policy Search to Identify Robust Strategies in Adapting to Uncertain Sea Level Rise and Storm Surge

Science.gov (United States)

Garner, G. G.; Keller, K.

2017-12-01

Sea-level rise poses considerable risks to coastal communities, ecosystems, and infrastructure. Decision makers are faced with deeply uncertain sea-level projections when designing a strategy for coastal adaptation. The traditional methods have provided tremendous insight into this decision problem, but are often silent on tradeoffs as well as the effects of tail-area events and of potential future learning. Here we reformulate a simple sea-level rise adaptation model to address these concerns. We show that Direct Policy Search yields improved solution quality, with respect to Pareto-dominance in the objectives, over the traditional approach under uncertain sea-level rise projections and storm surge. Additionally, the new formulation produces high quality solutions with less computational demands than the traditional approach. Our results illustrate the utility of multi-objective adaptive formulations for the example of coastal adaptation, the value of information provided by observations, and point to wider-ranging application in climate change adaptation decision problems.

Multidecadal variations in the early Holocene outflow of Red Sea Water into the Arabian Sea

OpenAIRE

Jung, S.J.A.; Ganssen, G.M.; Davies, G.R.

2001-01-01

We present Holocene stable oxygen isotope data from the deep Arabian Sea off Somalia at a decadal time resolution as a proxy for the history of intermediate/upper deep water. These data show an overall δ18O reduction by 0.5‰ between 10 and ~6.5 kyr B.P. superimposed upon short-term δ18O variations at a decadal-centennial timescale. The amplitude of the decadal variations is 0.3‰ prior, and up to 0.6‰ subsequent, to ~8.1 kyr B.P. We conclude from modeling experiments that the short-term δ18O v...

Munchausen by Proxy Syndrome

Science.gov (United States)

... the Child Getting Help for the Parent or Caregiver Print Munchausen by proxy syndrome (MBPS) is a relatively rare form of child abuse that involves the exaggeration or fabrication of illnesses or symptoms by a primary caretaker. Also known as "medical child abuse," MBPS ...

Boosting Blue Growth in a Mild Sea: Analysis of the Synergies Produced by a Multi-Purpose Offshore Installation in the Northern Adriatic, Italy

Directory of Open Access Journals (Sweden)

Barbara Zanuttigh

2015-05-01

Full Text Available In the near future, the oceans will be subjected to a massive development of marine infrastructures, including offshore wind, tidal and wave energy farms and constructions for marine aquaculture. The development of these facilities will unavoidably exert environmental pressures on marine ecosystems. It is therefore crucial that the economic costs, the use of marine space and the environmental impacts of these activities remain within acceptable limits. Moreover, the installation of arrays of wave energy devices is still far from being economically feasible due to many combined aspects, such as immature technologies for energy conversion, local energy storage and moorings. Therefore, multi-purpose solutions combining renewable energy from the sea (wind, wave, tide, aquaculture and transportation facilities can be considered as a challenging, yet advantageous, way to boost blue growth. This would be due to the sharing of the costs of installation and using the produced energy locally to feed the different functionalities and optimizing marine spatial planning. This paper focuses on the synergies that may be produced by a multi-purpose offshore installation in a relatively calm sea, i.e., the Northern Adriatic Sea, Italy, and specifically offshore Venice. It analyzes the combination of aquaculture, energy production from wind and waves, and energy storage or transfer. Alternative solutions are evaluated based on specific criteria, including the maturity of the technology, the environmental impact, the induced risks and the costs. Based on expert judgment, the alternatives are ranked and a preliminary layout of the selected multi-purpose installation for the case study is proposed, to further allow the exploitation of the synergies among different functionalities.

Dynamic ocean provinces: a multi-sensor approach to global marine ecophysiology

Science.gov (United States)

Dowell, M.; Campbell, J.; Moore, T.

The concept of oceanic provinces or domains has existed for well over a century. Such systems, whether real or only conceptual, provide a useful framework for understanding the mechanisms controlling biological, physical and chemical processes and their interactions. Criteria have been established for defining provinces based on physical forcings, availability of light and nutrients, complexity of the marine food web, and other factors. In general, such classification systems reflect the heterogeneous nature of the ocean environment, and the effort of scientists to comprehend the whole system by understanding its various homogeneous components. If provinces are defined strictly on the basis of geospatial or temporal criteria (e.g., latitude zones, bathymetry, or season), the resulting maps exhibit discontinuities that are uncharacteristic of the ocean. While this may be useful for many purposes, it is unsatisfactory in that it does not capture the dynamic nature of fluid boundaries in the ocean. Boundaries fixed in time and space do not allow us to observe interannual or longer-term variability (e.g., regime shifts) that may result from climate change. The current study illustrates the potential of using fuzzy logic as a means of classifying the ocean into objectively defined provinces using properties measurable from satellite sensors (MODIS and SeaWiFS). This approach accommodates the dynamic variability of provinces which can be updated as each image is processed. We adopt this classification as the basis for parameterizing specific algorithms for each of the classes. Once the class specific algorithms have been applied, retrievals are then recomposed into a single blended product based on the "weighted" fuzzy memberships. This will be demonstrated through animations of multi-year time- series of monthly composites of the individual classes or provinces. The provinces themselves are identified on the basis of global fields of chlorophyll, sea surface temperature

Reliability and validity of a self-administration version of DEMQOL-Proxy.

Science.gov (United States)

Hendriks, A A Jolijn; Smith, Sarah C; Chrysanthaki, Theopisti; Black, Nick

2017-07-01

This study aimed to investigate the reliability and validity of a self-administered version of DEMQOL-Proxy, a disease-specific instrument that measures health-related quality of life in people with dementia. The sample consisted of 173 informal carers of people with dementia, aged 29 to 89 years old. Carers were mostly female, White/White British and closely related to the patient. They completed DEMQOL-Proxy (self-administered), EQ-5D-3L (proxy reported about the person with dementia), EQ-5D-3L (self-reported about their own health) and the Zarit Burden Interview. Using well-established methods from classical test theory, we evaluated scale level acceptability, reliability and convergent, discriminant and known-groups validity of DEMQOL-Proxy. DEMQOL-Proxy (self-administered) showed high acceptability (3.5% missing data and 0% scores at floor or ceiling), high internal consistency reliability (α = 0.93) and good convergent and discriminant validity. Amongst others, we found a moderately high correlation with EQ-5D-3L proxy reported (r = 0.52) and low to essentially zero correlations with EQ-5D-3L self-reported (r = 0.20) and carer and patient background variables (r ≤ 0.20). As predicted, DEMQOL-Proxy (self-administered) showed a modest correlation with DEMQOL (r = 0.32). Known-groups differences on health-related quality of life (comparing people with versus people without cognitive impairment) were of moderate effect size (d = 0.38) and in the expected direction. DEMQOL-Proxy (self-administered) has comparable acceptability, reliability and validity with DEMQOL-Proxy (interviewer administered). DEMQOL-Proxy (self-administered) can be used in a wider variety of contexts than its interviewer-administered version, including routine use in busy clinics. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Validation and application of a death proxy in adult cancer patients.

Science.gov (United States)

Mealing, Nicole M; Dobbins, Timothy A; Pearson, Sallie-Anne

2012-07-01

PURPOSE: Fact of death is not always available on data sets used for pharmacoepidemiological research. Proxies may be an appropriate substitute in the absence of death data. The purposes of this study were to validate a proxy for death in adult cancer patients and to assess its performance when estimating survival in two cohorts of cancer patients. METHODS: We evaluated 30-, 60-, 90- and 180-day proxies overall and by cancer type using data from 12 394 Australian veterans with lung, colorectal, breast or prostate cancer. The proxy indicated death if the difference between the last dispensing record and the end of the observational period exceeded the proxy cutoff. We then compared actual survival to 90-day proxy estimates in a subset of 4090 veterans with 'full entitlements' for pharmaceutical items and in 3704 Australian women receiving trastuzumab for HER2+ metastatic breast cancer. RESULTS: The 90-day proxy was optimal with an overall sensitivity of 99.3% (95%CI: 98.4-99.7) and a specificity of 97.6% (95%CI: 91.8-99.4). These measures remained high when evaluated by cancer type and spread of disease. The application of the proxy using the most conservative date of death estimate (date of last dispensing) generally underestimated survival, with estimates up to 3 months shorter than survival based on fact of death. CONCLUSIONS: A 90-day death proxy is a robust substitute to identify death in a chronic population when fact of death is not available. The proxy is likely to be valid across a range of chronic diseases as it relies on the presence of 'regular' dispensing records for individual patients. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.

L1 Adaptive Control Augmentation System with Application to the X-29 Lateral/Directional Dynamics: A Multi-Input Multi-Output Approach

Science.gov (United States)

Griffin, Brian Joseph; Burken, John J.; Xargay, Enric

2010-01-01

This paper presents an L(sub 1) adaptive control augmentation system design for multi-input multi-output nonlinear systems in the presence of unmatched uncertainties which may exhibit significant cross-coupling effects. A piecewise continuous adaptive law is adopted and extended for applicability to multi-input multi-output systems that explicitly compensates for dynamic cross-coupling. In addition, explicit use of high-fidelity actuator models are added to the L1 architecture to reduce uncertainties in the system. The L(sub 1) multi-input multi-output adaptive control architecture is applied to the X-29 lateral/directional dynamics and results are evaluated against a similar single-input single-output design approach.

Sea level rise and the geoid: factor analysis approach

OpenAIRE

Song, Hongzhi; Sadovski, Alexey; Jeffress, Gary

2013-01-01

Sea levels are rising around the world, and this is a particular concern along most of the coasts of the United States. A 1989 EPA report shows that sea levels rose 5-6 inches more than the global average along the Mid-Atlantic and Gulf Coasts in the last century. The main reason for this is coastal land subsidence. This sea level rise is considered more as relative sea level rise than global sea level rise. Thus, instead of studying sea level rise globally, this paper describes a statistical...

Comparison of measurement- and proxy-based Vs30 values in California

Science.gov (United States)

Yong, Alan K.

2016-01-01

This study was prompted by the recent availability of a significant amount of openly accessible measured VS30 values and the desire to investigate the trend of using proxy-based models to predict VS30 in the absence of measurements. Comparisons between measured and model-based values were performed. The measured data included 503 VS30 values collected from various projects for 482 seismographic station sites in California. Six proxy-based models—employing geologic mapping, topographic slope, and terrain classification—were also considered. Included was a new terrain class model based on the Yong et al. (2012) approach but recalibrated with updated measured VS30 values. Using the measured VS30 data as the metric for performance, the predictive capabilities of the six models were determined to be statistically indistinguishable. This study also found three models that tend to underpredict VS30 at lower velocities (NEHRP Site Classes D–E) and overpredict at higher velocities (Site Classes B–C).

Tropical Hydroclimate Change during Heinrich Stadial 1: An Integrative Proxy-Model Synthesis

Science.gov (United States)

Lawman, A. E.; Sun, T.; Shanahan, T. M.; Di Nezio, P. N.; Gomez, K.; Piatrunia, N.; Sun, C.; Wu, X.; Kageyama, M.; Merkel, U.; Otto-Bliesner, B. L.; Abe-Ouchi, A.; Lohmann, G.; Singarayer, J. S.

2017-12-01

We explore the response of tropical climate to abrupt cooling of the North Atlantic (NA) during Heinrich Stadial 1 (HS1) combining paleoclimate proxies with model simulations. A total of 146 published paleoclimate records from tropical locations are used to categorize whether HS1 was wetter, drier, or unchanged relative to a deglacial baseline state. Only records with sufficient resolution to resolve HS1 and sufficient length to characterize the deglacial trend are considered. This synthesis reveals large-scale patterns of hydroclimate change relative to glacial conditions, confirming previously reported weaker Indian summer monsoon, a wetter southern Africa, and drying over the Caribbean. Our synthesis also reveals large-scale drying over the Maritime continent as well as wetter conditions in northern Australia and southern tropical South America. Our reinterpretation of the available proxy data reveals far more complexity and uncertainties for equatorial East Africa, a region that appears to straddle a pattern of dryer conditions to the north and wetter conditions to the south. Overall, these patterns of hydroclimate change depart from a southward shift of the Inter Tropical Convergence Zone (ITCZ), particularly outside the tropical Atlantic. We explore mechanisms driving these changes using a multi-model ensemble of "hosing" simulations performed relative to glacial conditions. The models show robust weakening of the Afro-Asian Monsoon, which we attribute to ventilation of colder mid-latitude air. Not all models simulate the remaining patterns inferred from the proxy data. The best-agreeing models indicate that cooling over the tropical NA and the Caribbean may be essential to communicate the response to the global tropics. This response can induce warming over the tropical South Atlantic via the wind-evaporation-SST feedback, driving wetter conditions in South Africa and tropical South America. Cooling over the Caribbean is communicated to the Pacific over the

Carbohydrates and phenols as quantitative molecular vegetation proxies in peats

Science.gov (United States)

Kaiser, K.; Benner, R. H.

2012-12-01

Vegetation in peatlands is intricately linked to local environmental conditions and climate. Here we use chemical analyses of carbohydrates and phenols to reconstruct paleovegetation in peat cores collected from 56.8°N (SIB04), 58.4°N (SIB06), 63.8°N (G137) and 66.5°N (E113) in the Western Siberian Lowland. Lignin phenols (vanillyl and syringyl phenols) were sensitive biomarkers for vascular plant contributions and provided additional information on the relative contributions of angiosperm and gymnosperm plants. Specific neutral sugar compositions allowed identification of sphagnum mosses, sedges (Cyperaceae) and lichens. Hydroxyphenols released by CuO oxidation were useful tracers of sphagnum moss contributions. The three independent molecular proxies were calibrated with a diverse group of peat-forming plants to yield quantitative estimates (%C) of vascular plant, sphagnum moss and lichen contributions in peat core samples. Correlation analysis indicated the three molecular proxies produced fairly similar results for paleovegetation compositions, generally within the error interval of each approach (≤26%). The lignin-based method generally lead to higher estimates of vascular plant vegetation. Several significant deviations were also observed due to different reactivities of carbohydrate and phenolic polymers during peat decomposition. Rapid vegetation changes on timescales of 50-200 years were observed in the southern cores SIB04 and SIB06 over the last 2000 years. Vanillyl and syringyl phenol ratios indicated these vegetation changes were largely due to varying inputs of angiosperm and gymnosperm plants. The northern permafrost cores G137 and E113 showed a more stable development. Lichens briefly replaced sphagnum mosses and vascular plants in both of these cores. Shifts in vegetation did not correlate well with Northern hemisphere climate variability over the last 2000 years. This suggested that direct climate forcing of peatland dynamics was overridden

A two-stage stochastic programming approach for operating multi-energy systems

DEFF Research Database (Denmark)

Zeng, Qing; Fang, Jiakun; Chen, Zhe

2017-01-01

This paper provides a two-stage stochastic programming approach for joint operating multi-energy systems under uncertainty. Simulation is carried out in a test system to demonstrate the feasibility and efficiency of the proposed approach. The test energy system includes a gas subsystem with a gas...

Sources and proxy potential of long chain alkyl diols in lacustrine environments

Science.gov (United States)

Rampen, Sebastiaan W.; Datema, Mariska; Rodrigo-Gámiz, Marta; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.

2014-11-01

Long chain 1,13- and 1,15-alkyl diols form the base of a number of recently proposed proxies used for climate reconstruction. However, the sources of these lipids and environmental controls on their distribution are still poorly constrained. We have analyzed the long chain alkyl diol (LCD) composition of cultures of ten eustigmatophyte species, with three species from different families grown at various temperatures, to identify the effect of species composition and growth temperature on the LCD distribution. The results were compared with the LCD distribution of sixty-two lake surface sediments, and with previously reported LCD distributions from marine environments. The different families within the Eustigmatophyceae show distinct LCD patterns, with the freshwater family Eustigmataceae most closely resembling LCD distributions in both marine and lake environments. Unlike the other two eustigmatophyte families analyzed (Monodopsidaceae and Goniochloridaceae), C28 and C30 1,13-alkyl diols and C30 and C32 1,15-alkyl diols are all relatively abundant in the family Eustigmataceae, while the mono-unsaturated C32 1,15-alkyl diol was below detection limit. In contrast to the marine environment, LCD distributions in lakes did not show a clear relationship with temperature. The Long chain Diol Index (LDI), a proxy previously proposed for sea surface temperature reconstruction, showed a relatively weak correlation (R2 = 0.33) with mean annual air temperature used as an approximation for annual mean surface temperature of the lakes. A much-improved correlation (R2 = 0.74, p-value cultures of the family Eustigmataceae, suggesting that algae belonging to this family have an important role as a source for LCDs in lacustrine environments, or, alternatively, that the main sources of LCDs are similarly affected by temperature as the Eustigmataceae. The results suggest that LCDs may have the potential to be applicable as a palaeotemperature proxy for lacustrine environments

Multi-proxy reconstructions of hydrologic change during the Eocene-Oligocene transition in the North American Interior

Science.gov (United States)

Eley, Y.; Hren, M. T.

2016-12-01

The dramatic shift from a 'greenhouse' to an 'icehouse' world that occurred during the Eocene-Oligocene transition (EOT, 34-33.5 Ma) is associated with changes in atmospheric and oceanic circulation patterns, extinction events in both marine and terrestrial ecosystems, and the establishment of a continental-scale ice sheet on Antarctica. Terrestrial records of the EOT, however, show limited consensus regarding the intensity and impact of this transition, complicating our understanding of how terrestrial hydrology responds to climatic change of this magnitude. Stable isotopes of fossil bones and teeth from the White River Group (WRG) in Nebraska have been interpreted to show an 8 °C decrease in mean annual temperatures across the EOT, with an increase in seasonality, however these studies find no evidence for accompanying changes in aridity. Conversely, other studies have inferred increased aridity in the early Oligocene based on changes in the δ18O and δ13C values of mammalian tooth enamel sampled from the same location. Some of this ambiguity is likely to stem from the difficulty in separating the influence of factors such as temperature, water availability and atmospheric circulation patterns on the δ18O composition of ungulate tooth enamel. We present paired leaf wax biomarker and clay hydrogen isotope data from the WRG to produce a new multi-proxy record of hydrological change and accompanying ecosystem shifts through the EOT in the North American interior. Hydrogen isotopes of clay minerals show a negative shift of record a negative shift in excess of 50‰, in tandem with a positive change in average chain length. We infer an increase in aridity from these data, with an associated potential shift in vegetation cover towards more savannah-style plant species as the climate became drier during the transition into the Oligocene. These data provide new constraints on the impact of the EOT in North America, and highlight the potential role of increasing

Boron isotopic compositions in growing corals from the South China Sea

Science.gov (United States)

Xiao, Jun; Xiao, Yingkai; Jin, Zhangdong; Liu, Congqiang; He, Maoyong

2013-01-01

In order to determine incorporation of boron species, boron isotopic fractionation, and influence of trace elements on isotopic compositions of boron in corals (δ11Bcoral), concentrations of Mg, Sr, Na, B and δ11Bcoral in growing corals from the South China Sea were measured. Relative to seawater, Sr enriched while Mg depleted in corals in the South China Sea. Although the δ11Bcoral values were different from various species and were not closely correlated with the element concentrations in corals in the South China Sea, Mg(OH)2 existed in corals can result in high δ11Bcoral. Thus, it is necessary to examine the existence of Mg(OH)2 and to choose the same species when δ11Bcoral is used in the δ11B-pH proxy. Based on the measured δ11B values of corals and coexisting seawater as well as the seawater pH in the South China Sea, a new isotopic fractionation factor a4-3 between B(OH)4- and B(OH)3 was determined to be 0.979. Besides B(OH)4- into corals, our results showed that B(OH)3 may also be incorporated into corals with variable proportions. The incorporation of B(OH)3 into corals may challenge the hypothesis of δ11Bcoral = δ11B4, resulting in increasing uncertainty to the calculated seawater pH values to the δ11B-pH proxy. We suggested that a best-fit empirical equation between δ11B of bio-carbonates and seawater pH needs to be established by the precipitation experiments of inorganic carbonates or culture experiments of corals or foraminifera.

Energetic Variational Approach to Multi-Component Fluid Flows

Science.gov (United States)

Kirshtein, Arkadz; Liu, Chun; Brannick, James

2017-11-01

In this talk I will introduce the systematic energetic variational approach for dissipative systems applied to multi-component fluid flows. These variational approaches are motivated by the seminal works of Rayleigh and Onsager. The advantage of this approach is that we have to postulate only energy law and some kinematic relations based on fundamental physical principles. The method gives a clear, quick and consistent way to derive the PDE system. I will compare different approaches to three-component flows using diffusive interface method and discuss their advantages and disadvantages. The diffusive interface method is an approach for modeling interactions among complex substances. The main idea behind this method is to introduce phase field labeling functions in order to model the contact line by smooth change from one type of material to another. The work of Arkadz Kirshtein and Chun Liu is partially supported by NSF Grants DMS-141200 and DMS-1216938.

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures.

Science.gov (United States)

Douglas, Peter M J; Affek, Hagit P; Ivany, Linda C; Houben, Alexander J P; Sijp, Willem P; Sluijs, Appy; Schouten, Stefan; Pagani, Mark

2014-05-06

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 °C in the southwest Pacific contrasting with SSTs between 5 and 15 °C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10-17 °C (1σ SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of ∼7 °C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 °C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands.

Fighting terrorism in Africa by proxy

DEFF Research Database (Denmark)

Olsen, Gorm Rye

2014-01-01

The French intervention in Mali in early 2013 emphasizes that the decision-makers in Paris, Brussels, and Washington considered the establishment of the radical Islamist regime in Northern Mali a threat to their security interests. The widespread instability including the rise of radical Islamist...... groups in Somalia was perceived as a threat to western interests. It is the core argument of the paper if western powers decide to provide security in Africa, they will be inclined to use proxy instead of deploying own troops. Security provision by proxy in African means that African troops are doing...

gLExec and MyProxy integration in the ATLAS/OSG PanDA workload management system

International Nuclear Information System (INIS)

Caballero, J; Hover, J; Maeno, T; Potekhin, M; Wenaus, T; Zhao, X; Litmaath, M; Nilsson, P

2010-01-01

Worker nodes on the grid exhibit great diversity, making it difficult to offer uniform processing resources. A pilot job architecture, which probes the environment on the remote worker node before pulling down a payload job, can help. Pilot jobs become smart wrappers, preparing an appropriate environment for job execution and providing logging and monitoring capabilities. PanDA (Production and Distributed Analysis), an ATLAS and OSG workload management system, follows this design. However, in the simplest (and most efficient) pilot submission approach of identical pilots carrying the same identifying grid proxy, end-user accounting by the site can only be done with application-level information (PanDA maintains its own end-user accounting), and end-user jobs run with the identity and privileges of the proxy carried by the pilots, which may be seen as a security risk. To address these issues, we have enabled PanDA to use gLExec, a tool provided by EGEE which runs payload jobs under an end-user's identity. End-user proxies are pre-staged in a credential caching service, MyProxy, and the information needed by the pilots to access them is stored in the PanDA DB. gLExec then extracts from the user's proxy the proper identity under which to run. We describe the deployment, installation, and configuration of gLExec, and how PanDA components have been augmented to use it. We describe how difficulties were overcome, and how security risks have been mitigated. Results are presented from OSG and EGEE Grid environments performing ATLAS analysis using PanDA and gLExec.

Towards Multi-Method Research Approach in Empirical Software Engineering

Science.gov (United States)

Mandić, Vladimir; Markkula, Jouni; Oivo, Markku

This paper presents results of a literature analysis on Empirical Research Approaches in Software Engineering (SE). The analysis explores reasons why traditional methods, such as statistical hypothesis testing and experiment replication are weakly utilized in the field of SE. It appears that basic assumptions and preconditions of the traditional methods are contradicting the actual situation in the SE. Furthermore, we have identified main issues that should be considered by the researcher when selecting the research approach. In virtue of reasons for weak utilization of traditional methods we propose stronger use of Multi-Method approach with Pragmatism as the philosophical standpoint.

The multi temporal/multi-model approach to predictive uncertainty assessment in real-time flood forecasting

Science.gov (United States)

Barbetta, Silvia; Coccia, Gabriele; Moramarco, Tommaso; Brocca, Luca; Todini, Ezio

2017-08-01

This work extends the multi-temporal approach of the Model Conditional Processor (MCP-MT) to the multi-model case and to the four Truncated Normal Distributions (TNDs) approach, demonstrating the improvement on the single-temporal one. The study is framed in the context of probabilistic Bayesian decision-making that is appropriate to take rational decisions on uncertain future outcomes. As opposed to the direct use of deterministic forecasts, the probabilistic forecast identifies a predictive probability density function that represents a fundamental knowledge on future occurrences. The added value of MCP-MT is the identification of the probability that a critical situation will happen within the forecast lead-time and when, more likely, it will occur. MCP-MT is thoroughly tested for both single-model and multi-model configurations at a gauged site on the Tiber River, central Italy. The stages forecasted by two operative deterministic models, STAFOM-RCM and MISDc, are considered for the study. The dataset used for the analysis consists of hourly data from 34 flood events selected on a time series of six years. MCP-MT improves over the original models' forecasts: the peak overestimation and the rising limb delayed forecast, characterizing MISDc and STAFOM-RCM respectively, are significantly mitigated, with a reduced mean error on peak stage from 45 to 5 cm and an increased coefficient of persistence from 0.53 up to 0.75. The results show that MCP-MT outperforms the single-temporal approach and is potentially useful for supporting decision-making because the exceedance probability of hydrometric thresholds within a forecast horizon and the most probable flooding time can be estimated.

PUMA Development through a Multi physics Approach

International Nuclear Information System (INIS)

Cheon, Jinsik; Kim, Junehyung; Lee, Byoungoon; Lee, Chanbock

2013-01-01

Meanwhile advances of numerical methods make it possible for the multi physics problem to be solved in a fully coupled way. In addition to a multidimensional, multi physical approach, a nuclear fuel performance analysis code, which is 1D code, should be improved by accommodating the state-of-the-art in the numerical analysis to support current fuel design and performance analysis. In particular, the coupling between the mechanical equilibrium equation and a set of numerically stiff kinetics equations for fission gas release is of great importance for a multi physics simulation of nuclear fuel. Instead, coupling between temperature and fuel constituent was found to be made with a relative ease by employing an ordinary differential equations solver. As an effort for a new SFR metal fuel performance analysis code, called PUMA (Performance of Uranium Metal fuel rod Analysis code), the deformation of U-Zr fuel for SFR in connection with a fission gas release model is analyzed. A finite element analyses for purely mechanical problems are performed using a backward differentiation formula, and are subjected to scrupulous verification with Abaqus. Then mechanical equilibrium equation and the equations for fission gas release are coupled with the same differential-algebraic equations (DAE) solver

Wavelength feature mapping as a proxy to mineral chemistry for investigating geologic systems: An example from the Rodalquilar epithermal system

Science.gov (United States)

van der Meer, Freek; Kopačková, Veronika; Koucká, Lucie; van der Werff, Harald M. A.; van Ruitenbeek, Frank J. A.; Bakker, Wim H.

2018-02-01

The final product of a geologic remote sensing data analysis using multi spectral and hyperspectral images is a mineral (abundance) map. Multispectral data, such as ASTER, Landsat, SPOT, Sentinel-2, typically allow to determine qualitative estimates of what minerals are in a pixel, while hyperspectral data allow to quantify this. As input to most image classification or spectral processing approach, endmembers are required. An alternative approach to classification is to derive absorption feature characteristics such as the wavelength position of the deepest absorption, depth of the absorption and symmetry of the absorption feature from hyperspectral data. Two approaches are presented, tested and compared in this paper: the 'Wavelength Mapper' and the 'QuanTools'. Although these algorithms use a different mathematical solution to derive absorption feature wavelength and depth, and use different image post-processing, the results are consistent, comparable and reproducible. The wavelength images can be directly linked to mineral type and abundance, but more importantly also to mineral chemical composition and subtle changes thereof. This in turn allows to interpret hyperspectral data in terms of mineral chemistry changes which is a proxy to pressure-temperature of formation of minerals. We show the case of the Rodalquilar epithermal system of the southern Spanish Gabo de Gata volcanic area using HyMAP airborne hyperspectral images.

Applicability of a cognitive questionnaire in the elderly and proxy

Directory of Open Access Journals (Sweden)

Renata Areza Fegyveres

Full Text Available Abstract The Informant Questionnaire on Cognitive Decline in the Elderly with the Proxy (IQCODE was developed as a screening tool for cognition alterations. Objectives: 1 To verify the applicability of IQCODE in the elderly with limited schooling, 2 To verify the reliability of the responses supplied by the aged and their proxies. Methods: Individuals of a Community Group were evaluated using the Mini-Mental State Examination (MMSE, IQCODE and Geriatric Depression Scale (GDS. The IQCODE was applied to informants and proxies. Results: We analyzed 44 individuals, aged between 58-82 years (M=66.8, SD=5.97 with mean elderly-schooling level of 3.75, SD=2.82 and 44 proxies aged 44.5 (SD=13.3, with mean schooling level of 8.25 (SD=4.3. The mean GDS was 8.22, SD=4.90 and 13 participants presented a score suggestive of depressive symptoms. The mean elderly IQCODE score was 3.26, SD=0.69 and 3.21, SD=0.65, for proxy responses. There was no statistical difference between these means. On the MMSE, the mean score was 24.20, SD=4.14 and 18 participants presented scores below the cut-off. The IQCODE answers by the elderly in this latter group were more congruent with MMSE than the answers of proxies. Conclusions: The applicability of the IQCODE in a population with little schooling was verified in that the proxy-report was similar to the elderly report. We can affirm that the elderly answers were more accurate than the proxies, as they were closer to MMSE score. The inclusion of a greater number of participants from community-dwelling settings is necessary to confirm the results obtained in this study.

Multimission satellite altimetric data validation in the Baltic Sea

DEFF Research Database (Denmark)

Cheng, Yongcun; Andersen, Ole Baltazar; Knudsen, Per

2014-01-01

The assessment of altimetric data is crucial for investigating the regional sea level variability. Few works has been performed to validate the altimetric data [1, 2] in the Baltic Sea. The exploring of multi-mission altimetric data in the Baltic Sea has yet to be published. The number of available...

Munchausen syndrome by proxy

Directory of Open Access Journals (Sweden)

Jovanović Aleksandar A.

2005-01-01

Full Text Available This review deals with bibliography on Munchausen syndrome by proxy (MSbP. The name of this disorder was introduced by English psychiatrist Roy Meadow who pointed to diagnostic difficulties as well as to serious medical and legal connotations of MSbP. MSbP was classified in DSM-IV among criteria sets provided for further study as "factitious disorder by proxy", while in ICD-10, though not explicitly cited, MSbP might be classified as "factitious disorders" F68.1. MSbP is a special form of abuse where the perpetrator induces somatic or mental symptoms of illness in the victim under his/her care and then persistently presents the victims for medical examinations and care. The victim is usually a preschool child and the perpetrator is the child's mother. Motivation for such pathological behavior of perpetrator is considered to be unconscious need to assume sick role by proxy while external incentives such as economic gain are absent. Conceptualization of MSbP development is still in the domain of psychodynamic speculation, its course is chronic and the prognosis is poor considering lack of consistent, efficient and specific treatment. The authors also present the case report of thirty-three year-old mother who had been abusing her nine year-old son both emotionally and physically over the last several years forcing him to, together with her, report to the police, medical and educational institutions that he had been the victim of rape, poisoning and beating by various individuals, especially teaching and medical staff. Mother manifested psychosis and her child presented with impaired cognitive development, emotional problems and conduct disorder.

Large-Scale Covariability Between Aerosol and Precipitation Over the 7-SEAS Region: Observations and Simulations

Science.gov (United States)

Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Zhang, Chidong; Jeong, Myeong Jae; Gautam, Ritesh; Bettenhausen, Corey; Sayer, Andrew M.; Hansell, Richard A.; Liu, Xiaohong;

Evaluation of patient and proxy responses on the activity measure for postacute care.

Science.gov (United States)

Jette, Alan M; Ni, Pengsheng; Rasch, Elizabeth K; Appelman, Jed; Sandel, M Elizabeth; Terdiman, Joseph; Chan, Leighton

2012-03-01

Our objective was to examine the agreement between adult patients with stroke and family member or clinician proxies in activity measure for postacute care (AM-PAC) summary scores for daily activity, basic mobility, and applied cognitive function. This study involved 67 patients with stroke admitted to a hospital within the Kaiser Permanente of Northern California system and were participants in a parent study on stroke outcomes. Each participant and proxy respondent completed the AM-PAC by personal or telephone interview at the point of hospital discharge or during ≥1 transitions to different postacute care settings. The results suggest that for patients with a stroke proxy, AM-PAC data are robust for family or clinician proxy assessment of basic mobility function and clinician proxy assessment of daily activity function, but less robust for family proxy assessment of daily activity function and for all proxy groups' assessments of applied cognitive function. The pattern of disagreement between patient and proxy was, on average, relatively small and random. There was little evidence of systematic bias between proxy and patient reports of their functional status. The degree of concordance between patient and proxy was similar for those with moderate to severe strokes compared with mild strokes. Patient and proxy ratings on the AM-PAC achieved adequate agreement for use in stroke research when using proxy respondents could reduce sample selection bias. The AM-PAC data can be implemented across institutional as well as community care settings while achieving precision and reducing respondent burden.

Interactive Fuzzy Goal Programming approach in multi-response stratified sample surveys

Directory of Open Access Journals (Sweden)

Gupta Neha

2016-01-01

Full Text Available In this paper, we applied an Interactive Fuzzy Goal Programming (IFGP approach with linear, exponential and hyperbolic membership functions, which focuses on maximizing the minimum membership values to determine the preferred compromise solution for the multi-response stratified surveys problem, formulated as a Multi- Objective Non Linear Programming Problem (MONLPP, and by linearizing the nonlinear objective functions at their individual optimum solution, the problem is approximated to an Integer Linear Programming Problem (ILPP. A numerical example based on real data is given, and comparison with some existing allocations viz. Cochran’s compromise allocation, Chatterjee’s compromise allocation and Khowaja’s compromise allocation is made to demonstrate the utility of the approach.

The dendroclimatic proxies from the northern Quebec taiga in the PAGES 2K network: recent advances and future developments.

Science.gov (United States)

Gennaretti, Fabio; Naulier, Maud; Arseneault, Dominique; Savard, Martine; Bégin, Christian; Boucher, Etienne; Bégin, Yves; Guiot, Joël

2016-04-01

Northeastern North America was historically underrepresented in the network of climate proxies used for climate reconstructions over the last two millennia. Indeed, in North America most high-resolution climate proxies are long tree-ring chronologies but, in Northeastern North America, these chronologies are highly challenging due to short tree longevity, high frequency and severity of wildfires and remoteness of many areas. Here, we will present the efforts accomplished during the last decade by our team in developing millennial-long tree-ring chronologies in the northern Quebec taiga. We sampled black spruce [Picea mariana (Mill.) B.S.P] subfossil tree remains naturally fallen in the littoral zone of six lakes to build six site-specific ring-width chronologies as well as two chronologies of stable isotope ratios (δ18O and δ13C in tree-ring cellulose). These chronologies, which are now included in the PAGES 2K network, were independently used to reconstruct summer temperature variations showing a well-expressed Medieval Climate Anomaly and the impact of volcanic and solar forcings at regional scale. We will also discuss non-climatic influences on these chronologies (i.e. wildfires and sampling height inconsistency), as well as the ongoing effort to extend the reconstructions in time to cover the last 2500 years. Finally, a new European funded project called MAIDEN-SPRUCE will be introduced. Within MAIDEN-SPRUCE, we will use a data-model approach to improve our understanding of the links between forests and climate over the last millennium. More specifically, we will adapt the process-based ecophysiological model MAIDENiso to investigate factors influencing the growth and underlying biogeochemical processes of black spruce. One of our objectives is to provide the first multi-proxy (ring widths and δ18O and δ13C in tree-ring cellulose) regional climate reconstruction in Eastern North America over the last millennium taking into account mechanistic rules

Influence of deep-water derived isoprenoid tetraether lipids on the TEXH86 paleothermometer in the Mediterranean Sea

NARCIS (Netherlands)

Kim, J.-H.; Schouten, Stefan; Rodrigo-Gámiz, Marta; Rampen, Sebastiaan; Marino, Gianluca; Huguet, Carme; Helmke, Peer; Buscail, Roselyne; Hopmans, Ellen C.; Pross, J.; Sangiorgi, Francesca; Middelburg, Jack B.M.; Sinninghe Damsté, Jaap S.

2015-01-01

The View the MathML sourceTEX86H paleothermometer based on isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) has widely been applied in various marine settings to reconstruct past sea surface temperatures (SSTs). However, it still remains uncertain how well this proxy reconstructs annual

The climate response of the Indo-Pacific warm pool to glacial sea level

Science.gov (United States)

Di Nezio, Pedro N.; Timmermann, Axel; Tierney, Jessica E.; Jin, Fei-Fei; Otto-Bliesner, Bette; Rosenbloom, Nan; Mapes, Brian; Neale, Rich; Ivanovic, Ruza F.; Montenegro, Alvaro

2016-06-01

Growing climate proxy evidence suggests that changes in sea level are important drivers of tropical climate change on glacial-interglacial timescales. These paleodata suggest that rainfall patterns over the Indo-Pacific warm pool (IPWP) are highly sensitive to the landmass configuration of the Maritime Continent and that lowered sea level contributed to large-scale drying during the Last Glacial Maximum (LGM, approximately 21,000 years B.P.). Using the Community Earth System Model Version 1.2 (CESM1), we investigate the mechanisms by which lowered sea level influenced the climate of the IPWP during the LGM. The CESM1 simulations show that, in agreement with previous hypotheses, changes in atmospheric circulation are initiated by the exposure of the Sunda and Sahul shelves. Ocean dynamical processes amplify the changes in atmospheric circulation by increasing the east-west sea surface temperature (SST) gradient along the equatorial Indian Ocean. The coupled mechanism driving this response is akin to the Bjerknes feedback and results in a large-scale climatic reorganization over the Indian Ocean with impacts extending from east Africa to the western tropical Pacific. Unlike exposure of the Sunda shelf, exposure of Sahul shelf and the associated changes in surface albedo play a key role because of the positive feedback. This mechanism could explain the pattern of dry (wet) eastern (western) Indian Ocean identified in climate proxies and LGM simulations. However, this response also requires a strengthened SST gradient along the equatorial Indian Ocean, a pattern that is not evident in marine paleoreconstructions. Strategies to resolve this issue are discussed.

Proxy-rated quality of life in Alzheimer's disease

DEFF Research Database (Denmark)

Vogel, Asmus; Bhattacharya, Suvosree; Waldorff, Frans Boch

2012-01-01

The study investigated the change in proxy rated quality of life (QoL) of a large cohort of home living patients with Alzheimer's disease (AD) over a period of 36 months.......The study investigated the change in proxy rated quality of life (QoL) of a large cohort of home living patients with Alzheimer's disease (AD) over a period of 36 months....

Exploring Multi-Scale Spatiotemporal Twitter User Mobility Patterns with a Visual-Analytics Approach

Directory of Open Access Journals (Sweden)

Junjun Yin

2016-10-01

Full Text Available Understanding human mobility patterns is of great importance for urban planning, traffic management, and even marketing campaign. However, the capability of capturing detailed human movements with fine-grained spatial and temporal granularity is still limited. In this study, we extracted high-resolution mobility data from a collection of over 1.3 billion geo-located Twitter messages. Regarding the concerns of infringement on individual privacy, such as the mobile phone call records with restricted access, the dataset is collected from publicly accessible Twitter data streams. In this paper, we employed a visual-analytics approach to studying multi-scale spatiotemporal Twitter user mobility patterns in the contiguous United States during the year 2014. Our approach included a scalable visual-analytics framework to deliver efficiency and scalability in filtering large volume of geo-located tweets, modeling and extracting Twitter user movements, generating space-time user trajectories, and summarizing multi-scale spatiotemporal user mobility patterns. We performed a set of statistical analysis to understand Twitter user mobility patterns across multi-level spatial scales and temporal ranges. In particular, Twitter user mobility patterns measured by the displacements and radius of gyrations of individuals revealed multi-scale or multi-modal Twitter user mobility patterns. By further studying such mobility patterns in different temporal ranges, we identified both consistency and seasonal fluctuations regarding the distance decay effects in the corresponding mobility patterns. At the same time, our approach provides a geo-visualization unit with an interactive 3D virtual globe web mapping interface for exploratory geo-visual analytics of the multi-level spatiotemporal Twitter user movements.

The effects of additional black carbon on the albedo of Arctic sea ice: variation with sea ice type and snow cover

OpenAIRE

A. A. Marks; M. D. King

2013-01-01

The response of the albedo of bare sea ice and snow-covered sea ice to the addition of black carbon is calculated. Visible light absorption and light-scattering cross-sections are derived for a typical first-year and multi-year sea ice with both "dry" and "wet" snow types. The cross-sections are derived using data from a 1970s field study that recorded both reflectivity and light penetration in Arctic sea ice and snow overlying sea ice. The variation of absorption cross-section ov...

Longitudinal proxy measurements in multiple sclerosis: patient-proxy agreement on the impact of MS on daily life over a period of two years

Directory of Open Access Journals (Sweden)

Thompson Alan J

2008-02-01

Full Text Available Abstract Background The use of self-report measurements in clinical settings is increasing. However, in patients with limitations that interfere with reliable self-assessment such as cognitive impairment or mood disturbances, as may be the case in multiple sclerosis (MS, data collection might be problematic. In these situations, information obtained from proxy respondents (e.g. partners may replace self-ratings. The aim of this study was to examine the value of proxy ratings at separate points in time and to assess patient-proxy agreement on possible changes in disease impact of MS. Methods Fifty-six MS patients and their partners completed the Multiple Sclerosis Impact Scale (MSIS-29 at baseline and follow-up, two years later. Patient-proxy agreement was assessed at both time points by calculating intraclass correlation coefficients (ICCs, exact and global agreement and the mean directional differences between groups. Agreement of change over time was assessed by calculating ICCs between change scores. In parallel, global ratings of both patients and proxy respondents of the extent to which the patient had improved or deteriorated over the past two years were collected to validate possible changes on the MSIS-29. Results At both time points, agreement on the physical scale was higher than agreement on the psychological scale (ICCs at baseline were 0.81 for the physical scale and 0.72 for the psychological scale; at follow-up, the ICC values were 0.86 and 0.65 respectively. At follow-up, statistically significant mean differences between patients and proxies were noted for the physical scale (-4.8 ± 12.7, p = 0.006 and the psychological scale (-8.9 ± 18.8, p = 0.001. Agreement between change scores on the MSIS-29 was fair (ICC Conclusion Proxy respondents could act as a reliable source of information in cross-sectional studies. Moreover, results suggested that agreement on change over time might be better for proxy respondents compared to

Decade to centennial resolution hydrogen isotopic record of climate change from southern New England for the past 16 kyr: proxy validation and multi-proxy comparisons

Science.gov (United States)

Huang, Y.; Gao, L.; Hou, J.; Shuman, B. N.; Oswald, W.; Foster, D.

2009-12-01

Open system lakes in New England offer excellent archives of precipitation isotopic ratios that yield quantitative paleoclimate information. We have demonstrated previously from a lake sediment transect that hydrogen isotopic ratios of a middle-chain length fatty acid, behenic acid (BA), faithfully record precipitation isotopic ratios. We hypothesized that mid-chain n-alkyl lipids in these small lakes were primarily derived from aquatic plants that record lake water isotopic ratios. To test this hypothesis, we conducted systematic and extensive sampling of both terrestrial and aquatic plants over the past two years at two typical kettle hole lakes, Blood Pond and Rocky Pond, MA, and used a linear algebra approach to delineate percentage inputs of aquatic and terrestrial plant contributions to mid-chain n-alkyl lipids. Our results demonstrate that >92 % of the mid-chain n-alkyl lipids is derived from submerged and floating aquatic macrophytes. Our new data provide a solid basis for the application of behenic hydrogen isotopic ratios as a paleoclimate proxy from small lakes. We will present a decadal to centennial scale 16 kyr record of BA hydrogen isotopic ratios from Blood Pond, and will discuss the results in light of published pollen and lake level data. Overall, our hydrogen isotopic record is fully consistent with regional climate scenarios, including the distinctive warming at B-A events, abrupt cooling at YD event, and transition from glacial to Holcoene climate conditions. However, our high-solution isotopic data provides important new insights concerning abrupt regional climate variability. We demonstrate that the New England climate is exceptionally senstive to AMOC changes and solar forcing and that many of the abrupt climate fluctuations exert major impacts on terrestrial ecosystems, hydrology and lake levels.

Confidence and sensitivity of sea-level reconstructions

DEFF Research Database (Denmark)

Svendsen, Peter Limkilde

For the last two decades, satellite altimetry has provided a near-global view of spatial and temporal patterns in sea surface height (SSH). When combined with records from tide gauges, a historical reconstruction of sea level can be obtained; while tide gauge records span up to 200 years back...... nature of the data fields. We examine the sensitivity of a reconstruction with respect to the length of calibration time series, and the spatial distribution of tide gauges or other proxy data. In addition, we consider the eect of isolating certain physical phenomena (e.g. ENSO) and annual signals...... and modelling these outside the reconstruction. The implementation is currently based on data from compound satellite datasets (i.e., two decades of altimetry), and the Simple Ocean Data Assimilation (SODA) model, an existing reconstruction, where a calibration period can be easily extracted and our model...

Towards a Usability and Error "Safety Net": A Multi-Phased Multi-Method Approach to Ensuring System Usability and Safety.

Science.gov (United States)

Kushniruk, Andre; Senathirajah, Yalini; Borycki, Elizabeth

2017-01-01

The usability and safety of health information systems have become major issues in the design and implementation of useful healthcare IT. In this paper we describe a multi-phased multi-method approach to integrating usability engineering methods into system testing to ensure both usability and safety of healthcare IT upon widespread deployment. The approach involves usability testing followed by clinical simulation (conducted in-situ) and "near-live" recording of user interactions with systems. At key stages in this process, usability problems are identified and rectified forming a usability and technology-induced error "safety net" that catches different types of usability and safety problems prior to releasing systems widely in healthcare settings.

The design and implementation about the project of optimizing proxy servers

International Nuclear Information System (INIS)

Wu Ling; Liu Baoxu

2006-01-01

Proxy server is an important facility in the network of an organization, which play an important role in security and access control and accelerating access of Internet. This article introduces the action of proxy servers, and expounds the resolutions to optimize proxy servers at IHEP: integration, dynamic domain name resolves and data synchronization. (authors)

Using Pteropod Shells to Trace Aragonite Dissolution: Toward a Multi-Basin Calibration

Science.gov (United States)

Mekik, F. A.

2013-12-01

We developed a new proxy for tracing aragonite dissolution in marine sediments. The core tops we used are from the tropical and subtropical latitudes of two ocean basins: Atlantic and Pacific. This allows for a multi-basin calibration for our proxy which is based on the fragmentation trend of pteropod shells. The ratio of fragmented pteropod shells to whole plus fragmented pteropod shells within our core tops has an excellent relationship with the aragonite saturation of bottom waters. Combining our pteropod-based aragonite dissolution proxy with the Globorotalia menradii Fragmentation Index, which is a calcite dissolution proxy, allows tracing carbonate chemistry of bottom waters for the entire ocean depth profile including regions well above the calcite saturation horizon. We also present new data on size normalized weights of pteropod shells which supports the aragonite dissolution trend seen in the pteropod fragmentation data. Unlike previous findings with other proxies, both aragonite and calcite dissolution data from a high resolution core in the western equatorial Pacific reveal no evidence of a degacial carbonate preservation maximum.

Operational validation of a multi-period and multi-criteria model conditioning approach for the prediction of rainfall-runoff processes in small forest catchments

Science.gov (United States)

Choi, H.; Kim, S.

2012-12-01

Most of hydrologic models have generally been used to describe and represent the spatio-temporal variability of hydrological processes in the watershed scale. Though it is an obvious fact that hydrological responses have the time varying nature, optimal values of model parameters were normally considered as time invariants or constants in most cases. The recent paper of Choi and Beven (2007) presents a multi-period and multi-criteria model conditioning approach. The approach is based on the equifinality thesis within the Generalised Likelihood Uncertainty Estimation (GLUE) framework. In their application, the behavioural TOPMODEL parameter sets are determined by several performance measures for global (annual) and short (30-days) periods, clustered using a Fuzzy C-means algorithm, into 15 types representing different hydrological conditions. Their study shows a good performance on the calibration of a rainfall-runoff model in a forest catchment, and also gives strong indications that it is uncommon to find model realizations that were behavioural over all multi-periods and all performance measures, and multi-period model conditioning approach may become new effective tool for predictions of hydrological processes in ungauged catchments. This study is a follow-up study on the Choi and Beven's (2007) model conditioning approach to test how the approach is effective for the prediction of rainfall-runoff responses in ungauged catchments. To achieve this purpose, 6 small forest catchments are selected among the several hydrological experimental catchments operated by Korea Forest Research Institute. In each catchment, long-term hydrological time series data varying from 10 to 30 years were available. The areas of the selected catchments range from 13.6 to 37.8 ha, and all areas are covered by coniferous or broad-leaves forests. The selected catchments locate in the southern coastal area to the northern part of South Korea. The bed rocks are Granite gneiss, Granite or

Late Holocene sea-level rise in Tampa Bay: Integrated reconstruction using biomarkers, pollen, organic-walled dinoflagellate cysts, and diatoms

NARCIS (Netherlands)

Soelen, E.E. van; Lammertsma, E.I.; Cremer, H.; Donders, T.H.; Sangiorgi, F.; Brooks, G.R.; Larson, R.A.; Sinninghe Damsté, J.S.; Wagner-Cremer, F.; Reichart, G.J.

2010-01-01

A suite of organic geochemical, micropaleontological and palynological proxies was applied to sediments from Southwest Florida, to study the Holocene environmental changes associated with sea-level rise. Sediments were recovered from Hillsborough Bay, part of Tampa Bay, and studied using biomarkers,

A multi-level surface rebalancing approach for efficient convergence acceleration of 3D full core multi-group fine grid nodal diffusion iterations

International Nuclear Information System (INIS)

Geemert, René van

2014-01-01

Highlights: • New type of multi-level rebalancing approach for nodal transport. • Generally improved and more mesh-independent convergence behavior. • Importance for intended regime of 3D pin-by-pin core computations. - Abstract: A new multi-level surface rebalancing (MLSR) approach has been developed, aimed at enabling an improved non-linear acceleration of nodal flux iteration convergence in 3D steady-state and transient reactor simulation. This development is meant specifically for anticipating computational needs for solving envisaged multi-group diffusion-like SP N calculations with enhanced mesh resolution (i.e. 3D multi-box up to 3D pin-by-pin grid). For the latter grid refinement regime, the previously available multi-level coarse mesh rebalancing (MLCMR) strategy has been observed to become increasingly inefficient with increasing 3D mesh resolution. Furthermore, for very fine 3D grids that feature a very fine axial mesh as well, non-convergence phenomena have been observed to emerge. In the verifications pursued up to now, these problems have been resolved by the new approach. The novelty arises from taking the interface current balance equations defined over all Cartesian box edges, instead of the nodal volume-integrated process-rate balance equation, as an appropriate restriction basis for setting up multi-level acceleration of fine grid interface current iterations. The new restriction strategy calls for the use of a newly derived set of adjoint spectral equations that are needed for computing a limited set of spectral response vectors per node. This enables a straightforward determination of group-condensed interface current spectral coupling operators that are of crucial relevance in the new rebalancing setup. Another novelty in the approach is a new variational method for computing the neutronic eigenvalue. Within this context, the latter is treated as a control parameter for driving another, newly defined and numerically more fundamental

Some Proxy Signature and Designated verifier Signature Schemes over Braid Groups

OpenAIRE

Lal, Sunder; Verma, Vandani

2009-01-01

Braids groups provide an alternative to number theoretic public cryptography and can be implemented quite efficiently. The paper proposes five signature schemes: Proxy Signature, Designated Verifier, Bi-Designated Verifier, Designated Verifier Proxy Signature And Bi-Designated Verifier Proxy Signature scheme based on braid groups. We also discuss the security aspects of each of the proposed schemes.

Reliability of proxy respondents for patients with stroke: a systematic review.

Science.gov (United States)

Oczkowski, Colin; O'Donnell, Martin

2010-01-01

Proxy respondents are an important aspect of stroke medicine and research. We performed a systematic review of studies evaluating the reliability of proxy respondents for stroke patients. Studies were identified by searches of MEDLINE, Google, and the Cochrane Library between January 1969 and June 2008. All were prospective or cross-sectional studies reporting the reliability of proxy respondents for patients with a history of previous stroke or transient ischemic attack. One author abstracted data. For each study, intraclass correlation (ICC) or the k-statistic was categorized as poor (0.80). Thirteen studies, with a total of 2618 participants, met our inclusion criteria. Most studies recruited patients >3 months after their stroke. Of these studies, 5 (360 participants; 5 scales) evaluated reliability of proxy respondents for activities of daily living (ADL), and 9 (2334 participants; 9 scales) evaluated reliability of proxy respondents for quality of life (QoL). One study evaluated both. In studies, the ICC/k for scales ranged from 0.61 to 0.91 for ADL and from 0.41 to 0.8 for QoL. Most studies reported that proxy respondents overestimated impairments compared with patient self-reports. Stroke severity and objective nature of questions were the most consistent determinants of disagreement between stroke patient and proxy respondent. Our data indicate that beyond the acute stroke period, the reliability of proxy respondents for validated scales of ADL was substantial to excellent, while that of scales for QoL was moderate to substantial. Copyright (c) 2010 National Stroke Association. Published by Elsevier Inc. All rights reserved.

SeaRAM: an evaluation of the safety of RAM transport by sea

International Nuclear Information System (INIS)

McConnell, P.; Sorenson, K.B.; Carter, M.H.; Keane, M.P.; Keith, V.F.; Heid, R.J.

1995-01-01

SeaRAM is a multi-year Department of Energy (DOE) project designed to validate the safety of shipping radioactive materials (RAM) by sea. The project has an ultimate goal of developing and demonstrating analytic tools for performing comprehensive analyses to evaluate the risks to humans and the environment due to sea transport of plutonium, vitrified high-level waste (VHLW), and spent fuel associated with reprocessing and research reactors. To achieve this end, evaluations of maritime databases and structural an thermal analyses of particular severe collision and fire accidents have been and will continue to be conducted. Program management for SeaRAM is based at the DOE's Office of Environmental Restoration. Technical activities for the project are being conducted at Sandia National Laboratories (SNL). Several private organizations are also involved in providing technical support, notably Engineering Computer Optecnomics, Inc. (ECO). The technical work performed for SeaRAM also supports DOE participation in an International Atomic Energy Agency (IAEA) Cooperative Research Program (CRP) entitled Accident Severity at Sea During Transport of Radioactive Material. This paper discusses activities performed during the first year of the project

Ground-truthing the Foraminifera-bound Nitrogen Isotope Paleo-proxy in the Modern Sargasso Sea

Science.gov (United States)

Smart, S.; Ren, H. A.; Fawcett, S. E.; Conte, M. H.; Rafter, P. A.; Ellis, K. K.; Weigand, M. A.; Sigman, D. M.

2016-02-01

We present the nitrogen isotope ratios (δ15N) of planktonic foraminifera, a type of calcifying zooplankton, collected from surface ocean net tows, moored sediment traps and core-top sediments at the Bermuda Atlantic Time-series Study site in the Sargasso Sea between 2009 and 2013. Consistent with previous measurements from low-latitude core-top sediments, the annually averaged δ15N of organic matter bound within the shells of euphotic zone-dwelling foraminifera approximates that of thermocline nitrate, the dominant source of new nitrogen to Sargasso Sea surface waters. Based on net tow collections in the upper 200 m of the water column, we observe no systematic difference between the biomass δ15N and shell-bound δ15N of a given foraminifera species. For multiple species, the δ15N of net tow-collected upper ocean shells is lower than shells from sediment traps (by 0.5-2.1‰) and lower than shells from seafloor sediments (by 0.5-1.4‰). We are currently investigating whether these differences reflect actual processes affecting shell-bound δ15N or instead relate to the different time periods over which the three sample types integrate. The foraminiferal biomass δ15N time-series from the surface Sargasso Sea exhibits significant seasonal variations, with the lowest values in fall and the highest values in spring. The roles of hydrography, biogeochemistry, and ecosystem dynamics in driving these seasonal variations will be discussed. These data from the modern subtropical ocean form part of a greater effort to ground-truth the use of foram-bound δ15N to reconstruct past nutrient conditions, not only as a recorder of the isotopic composition of nitrogen supply in oligotrophic environments but also as a recorder of the degree of nitrate consumption in high-latitude regions such as the Southern Ocean.

A Multi-homed VPN Architecture Based on Extended SOCKS+TLS Protocols

Institute of Scientific and Technical Information of China (English)

无

2005-01-01

A multi-homed VPN architecture based on extended SOCKSv5 and TLS was proposed. The architecture employs a dynamic connection mechanism for multiple proxies in the end system,in which the security-demanded transmission connections can switch smoothly among the multiple proxies by maintaining a coherent connection context. The mechanism is transparent to application programs and can support the building of VPN. With the cooperation of some other security components,the mechanism guarantees the resource availability and reliability of the end system against some attacks to the specific ports or hosts.

Proxy-produced ethnographic work: what are the problems, issues, and dilemmas arising from proxy ethnography?

DEFF Research Database (Denmark)

Martinussen, Marie Louise; Højbjerg, Karin; Tamborg, Andreas Lindenskov

2018-01-01

This article addresses the implications of research-student cooperation in the production of empirical material. For the student to replace the experienced researcher and work under the researcher’s supervision, we call such work proxy-produced ethnographic work. The specific relations...... and positions arising from such a setup between the teacher/researcher and the proxy ethnographer/student are found to have implications for the ethnographies produced. This article’s main focus is to show how these relations and positions have not distorted the ethnographic work and the ethnographies but......, rather, have oriented it in certain ways. It is shown how the participating researchers – both senior and junior - have distinctive, incorporated dispositions with which they pre-consciously participate in an implicit and subtle relation that can make it very easy to overlook distortions during...

Optimized swimmer tracking system based on a novel multi-related-targets approach

Science.gov (United States)

Benarab, D.; Napoléon, T.; Alfalou, A.; Verney, A.; Hellard, P.

2017-02-01

Robust tracking is a crucial step in automatic swimmer evaluation from video sequences. We designed a robust swimmer tracking system using a new multi-related-targets approach. The main idea is to consider the swimmer as a bloc of connected subtargets that advance at the same speed. If one of the subtargets is partially or totally occluded, it can be localized by knowing the position of the others. In this paper, we first introduce the two-dimensional direct linear transformation technique that we used to calibrate the videos. Then, we present the classical tracking approach based on dynamic fusion. Next, we highlight the main contribution of our work, which is the multi-related-targets tracking approach. This approach, the classical head-only approach and the ground truth are then compared, through testing on a database of high-level swimmers in training, national and international competitions (French National Championships, Limoges 2015, and World Championships, Kazan 2015). Tracking percentage and the accuracy of the instantaneous speed are evaluated and the findings show that our new appraoach is significantly more accurate than the classical approach.

Analyzing differences between patient and proxy on Patient Reported Outcomes in multiple sclerosis.

Science.gov (United States)

Sonder, Judith M; Holman, Rebecca; Knol, Dirk L; Bosma, Libertje V A E; Polman, Chris H; Uitdehaag, Bernard M J

2013-11-15

Proxy respondents, partners of multiple sclerosis (MS) patients, can provide valuable information on the MS patients' disease. In an earlier publication we found relatively good agreement on patient reported outcomes (PROs) measuring physical impact and functioning, but we found large differences on (neuro)psychological scales. We aim to identify patient and proxy related variables explaining differences between patients' and proxies' ratings on five PROs. We report on data from 175 MS patients and proxy respondents. Regression analyses were performed, using as dependent variable the mean differences on five scales: Physical and Psychological scale of the Multiple Sclerosis Impact Scale (MSIS-29), the Multiple Sclerosis Walking Scale (MSWS), Guy's Neurological Disability Scale (GNDS) and the Multiple Sclerosis Neuropsychological Screening Questionnaire (MSNQ). The independent variables were patient, proxy and disease related variables. Caregiver strain was significantly related to differences between patient and proxy scores for all five PROs. A higher level of patient anxiety on the HADS was linked to larger differences on all PROs except the GNDS. In addition, cognitive functioning, proxy depression, walking ability, proxy gender and MS related disability were contributing to the discrepancies. We found several patient and proxy factors that may contribute to discrepancies between patient and proxy scores on MS PROs. The most important factor is caregiver burden. © 2013 Elsevier B.V. All rights reserved.

Aligning and synchronization of MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for DEEP core chronology

Science.gov (United States)

Zanchetta, Giovanni; Regattieri, Eleonora; Giaccio, Biagio; Wagner, Bernd; Sulpizio, Roberto; Francke, Alex; Vogel, Hendrik; Sadori, Laura; Masi, Alessia; Sinopoli, Gaia; Lacey, Jack H.; Leng, Melanie J.; Leicher, Niklas

2016-05-01

The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through the marine isotope stages (MIS) 15-1. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed palaeoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. Here, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically dated Mediterranean marine and continental proxy records. The alternative age model presented here shows consistent differences with that initially proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this new age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how a detailed study of independent chronological tie points is important to align different records and to highlight asynchronisms of climate events. Moreover, Francke et al. (2016) have incorporated the new chronology proposed for tephra OH-DP-0499 in the final DEEP age model. This has reduced substantially the chronological discrepancies between the DEEP site age model and the model proposed here for the last glacial-interglacial transition.

Multi-criteria ACO-based Algorithm for Ship’s Trajectory Planning

Directory of Open Access Journals (Sweden)

Agnieszka Lazarowska

2017-03-01

Full Text Available The paper presents a new approach for solving a path planning problem for ships in the environment with static and dynamic obstacles. The algorithm utilizes a heuristic method, classified to the group of Swarm Intelligence approaches, called the Ant Colony Optimization. The method is inspired by a collective behaviour of ant colonies. A group of agents - artificial ants searches through the solution space in order to find a safe, optimal trajectory for a ship. The problem is considered as a multi-criteria optimization task. The criteria taken into account during problem solving are: path safety, path length, the International Regulations for Preventing Collisions at Sea (COLREGs compliance and path smoothness. The paper includes the description of the new multi-criteria ACO-based algorithm along with the presentation and discussion of simulation tests results.

The Difference Between Using Proxy Server and VPN

Directory of Open Access Journals (Sweden)

David Dwiputra Kurniadi

2015-11-01

For example, looking for software, game through internet. But sometimes, there are some websites that cannot be opened as they have Internet Positive notificatio. To solve that problem, hacker found the solution by creating Proxy Server or VPN. In this time internet is very modern and very easy to access and there are a lot of Proxy Server and VPN that can be easly used.

The Intra-Industry Effects of Proxy Contests

OpenAIRE

Fang Chen; Jian Huang; Han Yu

2018-01-01

This paper is the first study on the intra-industry effects of proxy contests. Using a sample of proxy contests from January 1988 through December 2008, we identify a striking cross-sectional difference in market reaction to the target companies. As much as 61% of the target firms have a significant positive cumulative abnormal return (CARs) in the period (‒10, +10) around the announcement day, while 39% of the target firms have the negative CARs in the same event window. Moreover, we find th...

Quality assurance in clinical trials : a multi-disciplinary approach

International Nuclear Information System (INIS)

Cornes, D.

2001-01-01

Full text: Multi-disciplinary groups, such as medical physicists and radiation therapists, which work effectively together, can ensure continued improvements in radiation therapy quality. The same is also true for clinical trials, which have the added complication of requiring multi-institutional participation to collate sufficient data to effectively assess treatment benefits. It can be difficult to manage quality across all aspects of a multi-disciplinary and multi-institutional trial. A planned system of quality assurance is necessary to provide support for participating centres and facilitate a collaborative approach. To ensure protocol compliance a good relationship between the clinical trial group and treatment centre is idea with definition of mutual goals and objectives before and during the trial, and ongoing consultation and feedback throughout the trial process. To ensure good quality data and maximise the validity of results the study protocol must be strictly adhered to. Because of the need for meticulous attention to detail, both in treatment delivery and standards of documentation, clinical trials are often seen to further complicate the process of delivery of radiation therapy treatment. The Declaration of Helsinki and Good Clinical Practise Guidelines (adopted in May 1996, ICH) provide 'international ethical and scientific standards for designing, conducting, recording and reporting clinical research' and multi-disciplinary groups in each participating centre should also adhere to these guidelines. Copyright (2001) Australasian College of Physical Scientists and Engineers in Medicine

Objective spatiotemporal proxy-model comparisons of the Asian monsoon for the last millennium

Science.gov (United States)

Anchukaitis, K. J.; Cook, E. R.; Ammann, C. M.; Buckley, B. M.; D'Arrigo, R. D.; Jacoby, G.; Wright, W. E.; Davi, N.; Li, J.

2008-12-01

The Asian monsoon system can be studied using a complementary proxy/simulation approach which evaluates climate models using estimates of past precipitation and temperature, and which subsequently applies the best understanding of the physics of the climate system as captured in general circulation models to evaluate the broad-scale dynamics behind regional paleoclimate reconstructions. Here, we use a millennial-length climate field reconstruction of monsoon season summer (JJA) drought, developed from tree- ring proxies, with coupled climate simulations from NCAR CSM1.4 and CCSM3 to evaluate the cause of large- scale persistent droughts over the last one thousand years. Direct comparisons are made between the external forced response within the climate model and the spatiotemporal field reconstruction. In order to identify patterns of drought associated with internal variability in the climate system, we use a model/proxy analog technique which objectively selects epochs in the model that most closely reproduce those observed in the reconstructions. The concomitant ocean-atmosphere dynamics are then interpreted in order to identify and understand the internal climate system forcing of low frequency monsoon variability. We examine specific periods of extensive or intensive regional drought in the 15th, 17th, and 18th centuries, many of which are coincident with major cultural changes in the region.

Architecture of a bi-directional Bluetooth-UPnP proxy

NARCIS (Netherlands)

Delphinanto, A.; Lukkien, J.J.; Koonen, A.M.J.; Hartog, F.T.H. den; Madureira, A.J.P.S.; Niemegeers, I.G.M.M.; Selgert, F.

2007-01-01

The current service- and device discovery protocols are not platform- and network independent Therefore, proxy servers will be needed to extend the range of IP-based discovery protocols to non-IP domains. We developed an architecture of a proxy that enables UPnP devices and services to be discovered

The drivers of sea lice management policies and how best to integrate them into a risk management strategy: An ecosystem approach to sea lice management.

Science.gov (United States)

Jackson, D; Moberg, O; Stenevik Djupevåg, E M; Kane, F; Hareide, H

2018-06-01

The control of sea lice infestations on cultivated Atlantic salmon is a major issue in many regions of the world. The numerous drivers which shape the priorities and objectives of the control strategies vary for different regions/jurisdictions. These range from the animal welfare and economic priorities of the producers, to the mitigation of any potential impacts on wild stocks. Veterinary ethics, environmental impacts of therapeutants, and impacts for organic certification of the produce are, amongst others, additional sets of factors which should be considered. Current best practice in both EU and international environmental law advocates a holistic ecosystem approach to assessment of impacts and risks. The issues of biosecurity and ethics, including the impacts on the stocks of species used as cleaner fish, are areas for inclusion in such a holistic ecosystem assessment. The Drivers, Pressures, State, Impacts, Responses (DPSIR) process is examined as a decision-making framework and potential applications to sea lice management are outlined. It is argued that this is required to underpin any integrated sea lice management (ISLM) strategy to balance pressures and outcomes and ensure a holistic approach to managing the issue of sea lice infestations on farmed stock on a medium to long-term basis. © 2017 The Authors. Journal of Fish Diseases Published by John Wiley & Sons Ltd.

Caspian Sea level changes during the last millennium: historical and geological evidences from the south Caspian Sea

Science.gov (United States)

Naderi Beni, A.; Lahijani, H.; Mousavi Harami, R.; Arpe, K.; Leroy, S. A. G.; Marriner, N.; Berberian, M.; Andrieu-Ponel, V.; Djamali, M.; Mahboubi, A.

2013-03-01

Historical literature may constitute a valuable source of information to reconstruct sea level changes. Here, historical documents and geological records have been combined to reconstruct Caspian sea-level (CSL) changes during the last millennium. In addition to a literature survey, new data from two short sediment cores were obtained from the south-eastern Caspian coast to identify coastal change driven by water-level changes. Two articulated bivalve shells from the marine facies were radiocarbon dated and calibrated to establish a chronology and to compare them with historical findings. The overall results indicate a high-stand during the Little Ice Age, up to -19 m, with a -28 m low-stand during the Medieval Climate Anomaly, while presently the CSL stands at -26.5 m. A comparison of the CSL curve with other lake systems and proxy records suggests that the main sea-level oscillations are essentially paced by solar irradiance. Although the major controller of the long-term CSL changes is driven by climatological factors, the seismicity of the basin could create locally changes in base level. These local base-level changes should be considered in any CSL reconstruction.