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3. Influence of hydrodynamics on many-particle diffusion in 2D colloidal suspensions

Author

Falck, E., Lahtinen, J. M., Vattulainen, I., and Ala-Nissila, T.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

We study many-particle diffusion in 2D colloidal suspensions with full hydrodynamic interactions through a novel mesoscopic simulation technique. We focus on the behaviour of the effective scaled tracer and collective diffusion coefficients $D_T(\rho) / D_0$ and $D_C(\rho) / D_0$, where $D_0$ is the single-particle diffusion coefficient, as a function of the density of the colloids $\rho$. At low Schmidt numbers $Sc={\cal O}(1)$, we find that hydrodynamics has essentially no effect on the behaviour of $D_T(\rho)/D_0$. At larger $Sc$, $D_T(\rho)/D_0$ is enhanced at all densities, although the differences compared to the case without hydrodynamics are minor. The collective diffusion coefficient, on the other hand, is much more strongly coupled to hydrodynamical conservation laws and is distinctly different from the purely dissipative case.

Published
2003
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4. Dynamics and Scaling of 2D Polymers in a Dilute Solution

Author

Falck, E., Punkkinen, O., Vattulainen, I., and Ala-Nissila, T.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

The breakdown of dynamical scaling for a dilute polymer solution in 2D has been suggested by Shannon and Choy [Phys. Rev. Lett. {\bf 79}, 1455 (1997)]. However, we show here both numerically and analytically that dynamical scaling holds when the finite-size dependence of the relevant dynamical quantities is properly taken into account. We carry out large-scale simulations in 2D for a polymer chain in a good solvent with full hydrodynamic interactions to verify dynamical scaling. This is achieved by novel mesoscopic simulation techniques.

Published
2003
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6. Molecular Dynamics Simulations of Lipid Bilayers: Major Artifacts due to Truncating Electrostatic Interactions

Author

Patra, M., Karttunen, M., Hyvonen, M., Falck, E., Lindqvist, P., and Vattulainen, I.

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Biological Physics
Abstract

We study the influence of truncating the electrostatic interactions in a fully hydrated pure dipalmitoylphosphatidylcholine (DPPC) bilayer through 20 ns molecular dynamics simulations. The computations in which the electrostatic interactions were truncated are compared to similar simulations using the Particle-Mesh Ewald (PME) technique. All examined truncation distances (1.8 to 2.5 nm) lead to major effects on the bilayer properties, such as enhanced order of acyl chains together with decreased areas per lipid. The results obtained using PME, on the other hand, are consistent with experiments. These artifacts are interpreted in terms of radial distribution functions $g(r)$ of molecules and molecular groups in the bilayer plane. Pronounced maxima or minima in g(r) appear exactly at the cutoff distance indicating that the truncation gives rise to artificial ordering between the polar phosphatidyl and choline groups of the DPPC molecules. In systems described using PME, such artificial ordering is not present.

Published
2002
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16. Dynamics and scaling of polymers in a dilute solution: Analytical treatment in two and higher dimensions.

Author

Punkkinen, O., Falck, E., Vattulainen, I., and Ala-Nissila, T.

Subjects
*POLYMERS, *FLUIDS, *SOLUTION (Chemistry), *COMPUTER simulation, *SIMULATION methods & models, *SOLVENTS
Abstract

We consider the dynamical scaling of a single polymer chain in good solvent. In the case of two-dimensional systems, Shannon and Choy [Phys. Rev. Lett. 79, 1455 (1997)] have suggested that the dynamical scaling for a dilute polymer solution breaks down. Using scaling arguments and analytical calculations based on the Zimm model, we show that the dynamical scaling of a dilute two-dimensional polymer system holds when the relevant dynamical quantities are properly extracted from finite systems. Most important, the polymer diffusion coefficient in two dimensions scales logarithmically with system size, in excellent agreement with our extensive computer simulations. This scaling is the reason for the failure of the previous attempts to resolve the dynamical scaling of dilute two-dimensional polymer systems. In three and higher dimensions our analytic calculations are in agreement with previous results in the literature. [ABSTRACT FROM AUTHOR]

Published
2005
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22. An important late summer aggregation of fin whales Balaenoptera physalus, little auks Alle alle and Brünnich’s guillemots Uria lomvia in the eastern Greenland Sea and Fram Strait: influence of hydrographic structures

Author

Joiris, C.R., Falck, E., D'Hert, D., Jungblut, S., and Boos, K.

Subjects
Aggregations (ecological)
Abstract

The distribution at sea of upper trophic levels—seabirds and marine mammals—is depending on their food availability: high concentrations reflect high prey abundance and thus high biological production. Polar marine ecosystems are characterized by low biodiversity and high biological patchiness. The distribution of predators, as a consequence, shows a similar patchiness. During two expeditions of icebreaking RV Polarstern in June–July 2011, biodiversity in the arctic marine zone north of 70°N was very low, with low numbers of species: 20 seabirds, eight cetaceans, five pinnipeds and polar bear. Moreover, a few species accounted for the majority in numbers: four bird species for 95 % of the total of 23,000 seabirds recorded during 700 transect counts: fulmar Fulmarus glacialis, kittiwake Rissa tridactyla, Brünnich’s guillemot Uria lomvia and little auk Alle alle. Among the marine mammals, 250 fin whales Balaenoptera physalus accounted for 80 % of the identified large cetaceans, 270 white-beaked dolphin Lagenorhynchus albirostris for 100 % of the small cetaceans and 180 harp seals Pagophilus groenlandica for 80 % of the identified pinnipeds. Their quantitative distribution was depending on water masses and oceanic fronts, large cetaceans—mainly fin whales—showing an important aggregation on the shelf slope off western Spitsbergen, as well as little auks and Brünnich’s guillemots. So that this zone, shelf slope and front of mixed Arctic/Atlantic Waters, showed unusually high seabird and cetacean concentrations. Seasonal factors possibly influencing their distribution are addressed.

Published
2014

23. Temporal Variability in Surface Water pCO2 in Adventfjorden (West Spitsbergen) With Emphasis on Physical and Biogeochemical Drivers.

Author

Ericson, Y., Falck, E., Chierici, M., Fransson, A., Kristiansen, S., Platt, S. M., Hermansen, O., and Myhre, C. L.

Abstract

Abstract: Seasonal and interannual variability in surface water partial pressure of CO2 (pCO2) and air‐sea CO2 fluxes from a West Spitsbergen fjord (IsA Station, Adventfjorden) are presented, and the associated driving forces are evaluated. Marine CO2 system data together with temperature, salinity, and nutrients, were collected at the IsA Station between March 2015 and June 2017. The surface waters were undersaturated in pCO2 with respect to atmospheric pCO2 all year round. The effects of biological activity (primary production/respiration) followed by thermal forcing on pCO2 were the most important drivers on a seasonal scale. The ocean was a sink for atmospheric CO2 with annual air‐sea CO2 fluxes of −36 ± 2 and −31 ± 2 g C·m−2·year−1 for 2015–2016 and 2016–2017, respectively, as estimated from the month of April. Waters of an Arctic origin dominated in 2015 and were replaced in 2016 by waters of a transformed Atlantic source. The CO2 uptake rates over the period of Arctic origin waters were significantly higher (2 mmol C·m−2·day−1) than the rates of the Atlantic origin waters of the following year. [ABSTRACT FROM AUTHOR]

Published
2018
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24. CARINA Data Synthesis Project

Author

Tanhua, Toste, Olsen, A., Hoppema, M., Jutterström, S., Schirnick, Carsten, van Heuven, S., Velo, A., Lin, X., Kozyr, A., Alvarez, M., Bakker, D.C.E., Brown, P., Falck, E., Jeansson, E., Lo Monaco, C., Olafsson, J., Perez, F.F., Pierrot, D., Rios, A.F., Sabine, C.L., Schuster, U., Steinfeldt, R., Stendardo, I., Anderson, L.G., Bates, N.R., Bellerby, R.G.J., Blindheim, J., Bullister, J.L., Gruber, N., Ishii, M., Johannessen, T., Jones, E.P., Köhler, J., Körtzinger, Arne, Metzl, N., Murata, A., Musielewicz, S., Omar, A.M., Olsson, K.A., de la Paz, M., Pfeil, B., Rey, F., Rhein, M., Skjelvan, I., Tilbrook, B., Wanninkhof, R., Mintrop, L., Wallace, Douglas W.R., and Key, R.M.

Published
2009

25. Das Verfahren der Wasserbestimmung

Author

Hoffmann, J. F., Brown, E., Duvel, J. W. T., Gräfe, E., Schwalbe, C. G., Falck, E., Karstens, H., Thörner, W., Fabris, U., Shutt, Fr. T., Charron, A. T., Mai, C., and Rheinberger, E.

Published
1913
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26. Temporal Variability in Surface Water pCO2in Adventfjorden (West Spitsbergen) With Emphasis on Physical and Biogeochemical Drivers

Author

Ericson, Y., Falck, E., Chierici, M., Fransson, A., Kristiansen, S., Platt, S. M., Hermansen, O., and Myhre, C. L.

Abstract

Seasonal and interannual variability in surface water partial pressure of CO2(pCO2) and air‐sea CO2fluxes from a West Spitsbergen fjord (IsA Station, Adventfjorden) are presented, and the associated driving forces are evaluated. Marine CO2system data together with temperature, salinity, and nutrients, were collected at the IsA Station between March 2015 and June 2017. The surface waters were undersaturated in pCO2with respect to atmospheric pCO2all year round. The effects of biological activity (primary production/respiration) followed by thermal forcing on pCO2were the most important drivers on a seasonal scale. The ocean was a sink for atmospheric CO2with annual air‐sea CO2fluxes of −36 ± 2 and −31 ± 2 g C·m−2·year−1for 2015–2016 and 2016–2017, respectively, as estimated from the month of April. Waters of an Arctic origin dominated in 2015 and were replaced in 2016 by waters of a transformed Atlantic source. The CO2uptake rates over the period of Arctic origin waters were significantly higher (2 mmol C·m−2·day−1) than the rates of the Atlantic origin waters of the following year. Large undersaturation of surface water pCO2with respect to atmospheric pCO2was observed in an Arctic fjord following two annual cyclesBiological activity and temperature are key drivers for the observed monthly variability in surface water pCO2The uptake of CO2is enhanced when Arctic origin waters are present in the fjord as compared to Atlantic origin waters

Published
2018
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31. Overview of the Nordic Seas CARINA data and salinity measurements

Author

Olsen, A., primary, Key, R. M., additional, Jeansson, E., additional, Falck, E., additional, Olafsson, J., additional, van Heuven, S., additional, Skjelvan, I., additional, Omar, A. M., additional, Olsson, K. A., additional, Anderson, L. G., additional, Jutterström, S., additional, Rey, F., additional, Johannessen, T., additional, Bellerby, R. G. J., additional, Blindheim, J., additional, Bullister, J. L., additional, Pfeil, B., additional, Lin, X., additional, Kozyr, A., additional, Schirnick, C., additional, Tanhua, T., additional, and Wallace, D. W. R., additional

Published
2009
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33. Carina Data Synthesis Project

Author

Tanhua,, T., primary, Olsen,, A., primary, Hoppema,, M., primary, Jutterstrom,, S., primary, Schirnick,, C., primary, van Heuven,, S., primary, Velo,, A., primary, Lin,, X., primary, Kozyr,, A., primary, Alvarez,, M., primary, Bakker,, D.C.E., primary, Brown,, P., primary, Falck,, E., primary, Jeansson,, E., primary, Lo Monaco,, C., primary, Olafsson,, J., primary, Perez,, F.F., primary, Pierrot,, D., primary, Rios,, A.F., primary, Sabine,, C.L., primary, Schuster,, U., primary, Steinfeldt,, R., primary, Stendardo,, I., primary, Anderson,, L.G., primary, Bates,, N.R., primary, Bellerby,, R.G.J., primary, Blindheim,, J., primary, Bullister,, J.L., primary, Gruber,, N., primary, Ishii,, M., primary, Johannessen,, T., primary, Jones,, E.P., primary, Kohler,, J., primary, Kortzinger,, A., primary, Metzl,, N., primary, Murata,, A., primary, Musielewics,, S., primary, Omar,, A.M., primary, Olsson,, K.A., primary, Pfeil,, B., primary, Rey,, F., primary, Rhein,, M., primary, Skjelvan,, I., primary, Tilbrook,, B., primary, Wanninkhof,, R., primary, Mintrop,, L., primary, Wallace,, D.W.R., primary, and Key,, R.M, primary

Published
2009
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34. Carbon in the Atlantic Ocean Region - the CARINA project: Results and Data, Version 1.0

Author

Tanhua,, T., primary, Olsen,, A., primary, Hoppema,, M., primary, Jutterstrom,, S., primary, Schirnick,, C., primary, van Heuven,, S., primary, Velo,, A., primary, Lin,, X., primary, Kozyr,, A., primary, Alvarez,, M., primary, Bakker,, D.C.E., primary, Brown,, P., primary, Falck,, E., primary, Jeansson,, E., primary, Lo Monaco,, C., primary, Olafsson,, J., primary, Perez,, F.F., primary, Pierrot,, D., primary, Rios,, A.F., primary, Sabine,, C.L., primary, Schuster,, U., primary, Steinfeldt,, R., primary, Stendardo,, I., primary, Anderson,, L.G., primary, Bates,, N.R., primary, Bellerby,, R.G.J., primary, Blindheim,, J., primary, Bullister,, J.L., primary, Gruber,, N., primary, Ishii,, M., primary, Johannessen,, T., primary, Jones,, E.P., primary, Kohler,, J., primary, Kortzinger,, A., primary, Metzl,, N., primary, Murata,, A., primary, Musielewics,, S., primary, Omar,, A.M., primary, Olsson,, K.A., primary, Pfeil,, B., primary, Rey,, F., primary, Rhein,, M., primary, Skjelvan,, I., primary, Tilbrook,, B., primary, Wanninkhof,, R., primary, Mintrop,, L., primary, Wallace,, D.W.R., primary, and Key,, R.M, primary

Published
2009
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35. Carbon in the Southern Ocean Region - the CARINA project: Results and Data, Version 1.0

Author

Tanhua,, T., primary, Olsen,, A., primary, Hoppema,, M., primary, Jutterstrom,, S., primary, Schirnick,, C., primary, van Heuven,, S., primary, Velo,, A., primary, Lin,, X., primary, Kozyr,, A., primary, Alvarez,, M., primary, Bakker,, D.C.E., primary, Brown,, P., primary, Falck,, E., primary, Jeansson,, E., primary, Lo Monaco,, C., primary, Olafsson,, J., primary, Perez,, F.F., primary, Pierrot,, D., primary, Rios,, A.F., primary, Sabine,, C.L., primary, Schuster,, U., primary, Steinfeldt,, R., primary, Stendardo,, I., primary, Anderson,, L.G., primary, Bates,, N.R., primary, Bellerby,, R.G.J., primary, Blindheim,, J., primary, Bullister,, J.L., primary, Gruber,, N., primary, Ishii,, M., primary, Johannessen,, T., primary, Jones,, E.P., primary, Kohler,, J., primary, Kortzinger,, A., primary, Metzl,, N., primary, Murata,, A., primary, Musielewics,, S., primary, Omar,, A.M., primary, Olsson,, K.A., primary, Pfeil,, B., primary, Rey,, F., primary, Rhein,, M., primary, Skjelvan,, I., primary, Tilbrook,, B., primary, Wanninkhof,, R., primary, Mintrop,, L., primary, Wallace,, D.W.R., primary, and Key,, R.M, primary

Published
2009
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36. Carbon in the Arctic Mediterranean Seas Region - the CARINA project: Results and Data, Version 1.1.

Author

Tanhua,, T., primary, Olsen,, A., primary, Hoppema,, M., primary, Jutterstrom,, S., primary, Schirnick,, C., primary, van Heuven,, S., primary, Velo,, A., primary, Lin,, X., primary, Kozyr,, A., primary, Alvarez,, M., primary, Bakker,, D.C.E., primary, Brown,, P., primary, Falck,, E., primary, Jeansson,, E., primary, Lo Monaco,, C., primary, Olafsson,, J., primary, Perez,, F.F., primary, Pierrot,, D., primary, Rios,, A.F., primary, Sabine,, C.L., primary, Schuster,, U., primary, Steinfeldt,, R., primary, Stendardo,, I., primary, Anderson,, L.G., primary, Bates,, N.R., primary, Bellerby,, R.G.J., primary, Blindheim,, J., primary, Bullister,, J.L., primary, Gruber,, N., primary, Ishii,, M., primary, Johannessen,, T., primary, Jones,, E.P., primary, Kohler,, J., primary, Kortzinger,, A., primary, Metzl,, N., primary, Murata,, A., primary, Musielewics,, S., primary, Omar,, A.M., primary, Olsson,, K.A., primary, Pfeil,, B., primary, Rey,, F., primary, Rhein,, M., primary, Skjelvan,, I., primary, Tilbrook,, B., primary, Wanninkhof,, R., primary, Mintrop,, L., primary, Wallace,, D.W.R., primary, and Key,, R.M, primary

Published
2009
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