TY  - JOUR
A1  - Wickert, Andrew D.
A1  - Schildgen, Taylor F.
T1  - Long-profile evolution of transport-limited gravel-bed rivers
JF  - Earth surface dynamics
N2  - Alluvial and transport-limited bedrock rivers constitute the majority of fluvial systems on Earth. Their long profiles hold clues to their present state and past evolution. We currently possess first-principles-based governing equations for flow, sediment transport, and channel morphodynamics in these systems, which we lack for detachment-limited bedrock rivers. Here we formally couple these equations for transport-limited gravel-bed river long-profile evolution. The result is a new predictive relationship whose functional form and parameters are grounded in theory and defined through experimental data. From this, we produce a power-law analytical solution and a finite-difference numerical solution to long-profile evolution. Steady-state channel concavity and steepness are diagnostic of external drivers: concavity decreases with increasing uplift rate, and steepness increases with an increasing sediment-to-water supply ratio. Constraining free parameters explains common observations of river form: to match observed channel concavities, gravel-sized sediments must weather and fine - typically rapidly - and valleys typically should widen gradually. To match the empirical square-root width-discharge scaling in equilibrium-width gravel-bed rivers, downstream fining must occur. The ability to assign a cause to such observations is the direct result of a deductive approach to developing equations for landscape evolution.
Y1  - 2019
U6  - https://doi.org/10.5194/esurf-7-17-2019
SN  - 2196-6311
SN  - 2196-632X
VL  - 7
IS  - 1
SP  - 17
EP  - 43
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Uber, Magdalena
A1  - Vandervaere, Jean-Pierre
A1  - Zin, Isabella
A1  - Braud, Isabelle
A1  - Heistermann, Maik
A1  - Legout, Cedric
A1  - Molinie, Gilles
A1  - Nord, Guillaume
T1  - How does initial soil moisture influence the hydrological response? A case study from southern France
JF  - Hydrology and earth system sciences : HESS
N2  - The phi(ev) is calculated from high-resolution discharge and precipitation data for several rain events with a cumulative precipitation P-cum ranging from less than 5mm to more than 80 mm. Because of the high uncertainty of phi(ev) associated with the hydrograph separation method, phi(ev) is calculated with several methods, including graphical methods, digital filters and a tracer-based method. The results indicate that the hydrological response depends on (theta) over bar (ini): during dry conditions phi(ev) is consistently below 0.1, even for events with high and intense precipitation. Above a threshold of (theta) over bar (ini) = 34 vol % phi(ev) can reach values up to 0.99 but there is a high scatter. Some variability can be explained with a weak correlation of phi(ev) with P-cum and rain intensity, but a considerable part of the variability remains unexplained. It is concluded that threshold-based methods can be helpful to prevent overestimation of the hydrological response during dry catchment conditions. The impact of soil moisture on the hydrological response during wet catchment conditions, however, is still insufficiently understood and cannot be generalized based on the present results.
Y1  - 2018
U6  - https://doi.org/10.5194/hess-22-6127-2018
SN  - 1027-5606
SN  - 1607-7938
VL  - 22
IS  - 12
SP  - 6127
EP  - 6146
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Milewski, Robert
A1  - Chabrillat, Sabine
A1  - Behling, Robert
T1  - Analyses of Recent Sediment Surface Dynamic of a Namibian Kalahari Salt Pan Based on Multitemporal Landsat and Hyperspectral Hyperion Data
JF  - Remote Sensing
N2  - This study combines spaceborne multitemporal and hyperspectral data to analyze the spatial distribution of surface evaporite minerals and changes in a semi-arid depositional environment associated with episodic flooding events, the Omongwa salt pan (Kalahari, Namibia). The dynamic of the surface crust is evaluated by a change-detection approach using the Iterative-reweighted Multivariate Alteration Detection (IR-MAD) based on the Landsat archive imagery from 1984 to 2015. The results show that the salt pan is a highly dynamic and heterogeneous landform. A change gradient is observed from very stable pan border to a highly dynamic central pan. On the basis of hyperspectral EO-1 Hyperion images, the current distribution of surface evaporite minerals is characterized using Spectral Mixture Analysis (SMA). Assessment of field and image endmembers revealed that the pan surface can be categorized into three major crust types based on diagnostic absorption features and mineralogical ground truth data. The mineralogical crust types are related to different zones of surface change as well as pan morphology that influences brine flow during the pan inundation and desiccation cycles. These combined information are used to spatially map depositional environments where the more dynamic halite crust concentrates in lower areas although stable gypsum and calcite/sepiolite crusts appear in higher elevated areas.
KW  - salt pan
KW  - playa
KW  - hyperspectral
KW  - multitemporal
KW  - change detection
KW  - evaporite minerals
Y1  - 2016
U6  - https://doi.org/10.3390/rs9020170
SN  - 2072-4292
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Schinköth, Michaela
A1  - Brand, Ralf
T1  - Automatic associations and the affective valuation of exercise
BT  - disentangling the type-1 process of the affective–reflective theory of physical inactivity and exercise
JF  - German Journal of Exercise and Sport Research
N2  - The decision to exercise is not only bound to rational considerations but also automatic affective processes. The affective–reflective theory of physical inactivity and exercise (ART) proposes a theoretical framework for explaining how the automatic affective process (type‑1 process) will influence exercise behavior, i.e., through the automatic activation of exercise-related associations and a subsequent affective valuation of exercise. This study aimed to empirically test this assumption of the ART with data from 69 study participants. A single-measurement study, including within-subject experimental variation, was conducted. Automatic associations with exercise were first measured with a single-target implicit association test. The somato-affective core of the participants’ automatic valuation of exercise-related pictures was then assessed via heart rate variability (HRV) analysis, and the affective valence of the valuation was tested with a facial expression (FE; smile and frown) task. Exercise behavior was assessed via self-report. Multiple regression (path) analysis revealed that automatic associations predicted HRV reactivity (β = −0.24, p = .044); the signs of the correlation between automatic associations and the smile FE score was in the expected direction but remained nonsignificant (β = −0.21, p = .078). HRV reactivity predicted self-reported exercise behavior (β = −0.28, p = .013) (the same pattern of results was achieved for the frown FE score). The HRV-related results illustrate the potential role of automatic negative affective reactions to the thought of exercise as a restraining force in exercise motivation. For better empirical distinction between the two ART type‑1 process components, automatic associations and the affective valuation should perhaps be measured separately in the future. The results support the notion that automatic and affective processes should be regarded as essential aspects of the motivation to exercise.
KW  - Heart rate variability
KW  - Facial expression
KW  - Somatic
KW  - Dual-process
KW  - Motivation
Y1  - 2019
U6  - https://doi.org/10.1007/s12662-020-00664-9
SN  - 2509-3150
SN  - 2509-3142
VL  - 50
IS  - 654
SP  - 366
EP  - 376
PB  - Springer
CY  - Berlin ; Heidelberg
ER  - 
TY  - JOUR
A1  - Mardoukhi, Yousof
A1  - Chechkin, Aleksei V.
A1  - Metzler, Ralf
T1  - Spurious ergodicity breaking in normal and fractional Ornstein–Uhlenbeck process
JF  - New Journal of Physics
N2  - The Ornstein–Uhlenbeck process is a stationary and ergodic Gaussian process, that is fully determined by its covariance function and mean. We show here that the generic definitions of the ensemble- and time-averaged mean squared displacements fail to capture these properties consistently, leading to a spurious ergodicity breaking. We propose to remedy this failure by redefining the mean squared displacements such that they reflect unambiguously the statistical properties of any stochastic process. In particular we study the effect of the initial condition in the Ornstein–Uhlenbeck process and its fractional extension. For the fractional Ornstein–Uhlenbeck process representing typical experimental situations in crowded environments such as living biological cells, we show that the stationarity of the process delicately depends on the initial condition.
KW  - Ornstein–Uhlenbeck process
KW  - stationary stochastic process
KW  - ensemble and time averaged mean squared displacement
Y1  - 2020
U6  - https://doi.org/10.1088/1367-2630/ab950b
SN  - 1367-2630
VL  - 22
PB  - IOP
CY  - London
ER  - 
TY  - JOUR
A1  - Lonsdorf, Tina B.
A1  - Klingelhöfer-Jens, Maren
A1  - Andreatta, Marta
A1  - Beckers, Tom
A1  - Chalkia, Anastasia
A1  - Gerlicher, Anna
A1  - Jentsch, Valerie L.
A1  - Drexler, Shira Meir
A1  - Mertens, Gaetan
A1  - Richter, Jan
A1  - Sjouwerman, Rachel
A1  - Wendt, Julia
A1  - Merz, Christian J.
T1  - Navigating the garden of forking paths for data exclusions in fear conditioning research
JF  - eLife
N2  - In this report, we illustrate the considerable impact of researcher degrees of freedom with respect to exclusion of participants in paradigms with a learning element. We illustrate this empirically through case examples from human fear conditioning research, in which the exclusion of ‘non-learners’ and ‘non-responders’ is common – despite a lack of consensus on how to define these groups. We illustrate the substantial heterogeneity in exclusion criteria identified in a systematic literature search and highlight the potential problems and pitfalls of different definitions through case examples based on re-analyses of existing data sets. On the basis of these studies, we propose a consensus on evidence-based rather than idiosyncratic criteria, including clear guidelines on reporting details. Taken together, we illustrate how flexibility in data collection and analysis can be avoided, which will benefit the robustness and replicability of research findings and can be expected to be applicable to other fields of research that involve a learning element.
Y1  - 2019
U6  - https://doi.org/10.7554/eLife.52465
SN  - 2050-084X
VL  - 8
PB  - eLife Sciences Publications
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Lonsdorf, Tina B.
A1  - Klingelhöfer-Jens, Maren
A1  - Andreatta, Marta
A1  - Beckers, Tom
A1  - Chalkia, Anastasia
A1  - Gerlicher, Anna Maria Veronika
A1  - Jentsch, Valerie L.
A1  - Drexler, Shira Meir
A1  - Mertens, Gaetan
A1  - Richter, Jan
A1  - Sjouwerman, Rachel
A1  - Wendt, Julia
A1  - Merz, Christian J.
T1  - Navigating the garden of forking paths for data exclusions in fear conditioning research
JF  - eLife
Y1  - 2019
U6  - https://doi.org/10.7554/eLife.52465
SN  - 2050-084X
VL  - 8
PB  - eLife Sciences Publications
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Günther, Erika
A1  - Klauß, André
A1  - Toro-Nahuelpan, Mauricio
A1  - Schüler, Dirk
A1  - Hille, Carsten
A1  - Faivre, Damien
T1  - The in vivo mechanics of the magnetotactic backbone as revealed by correlative FLIM-FRET and STED microscopy
JF  - Scientific reports
N2  - Protein interaction and protein imaging strongly benefit from the advancements in time-resolved and superresolution fluorescence microscopic techniques. However, the techniques were typically applied separately and ex vivo because of technical challenges and the absence of suitable fluorescent protein pairs. Here, we show correlative in vivo fluorescence lifetime imaging microscopy Forster resonance energy transfer (FLIM-FRET) and stimulated emission depletion (STED) microscopy to unravel protein mechanics and structure in living cells. We use magnetotactic bacteria as a model system where two proteins, MamJ and MamK, are used to assemble magnetic particles called magnetosomes. The filament polymerizes out of MamK and the magnetosomes are connected via the linker MamJ. Our system reveals that bacterial filamentous structures are more fragile than the connection of biomineralized particles to this filament. More importantly, we anticipate the technique to find wide applicability for the study and quantification of biological processes in living cells and at high resolution.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-55804-5
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Thomas, Jessica E.
A1  - Carvalho, Gary R.
A1  - Haile, James
A1  - Rawlence, Nicolas J.
A1  - Martin, Michael D.
A1  - Ho, Simon Y. W.
A1  - Sigfusson, Arnor P.
A1  - Josefsson, Vigfus A.
A1  - Frederiksen, Morten
A1  - Linnebjerg, Jannie F.
A1  - Castruita, Jose A. Samaniego
A1  - Niemann, Jonas
A1  - Sinding, Mikkel-Holger S.
A1  - Sandoval-Velasco, Marcela
A1  - Soares, Andre E. R.
A1  - Lacy, Robert
A1  - Barilaro, Christina
A1  - Best, Juila
A1  - Brandis, Dirk
A1  - Cavallo, Chiara
A1  - Elorza, Mikelo
A1  - Garrett, Kimball L.
A1  - Groot, Maaike
A1  - Johansson, Friederike
A1  - Lifjeld, Jan T.
A1  - Nilson, Goran
A1  - Serjeanston, Dale
A1  - Sweet, Paul
A1  - Fuller, Errol
A1  - Hufthammer, Anne Karin
A1  - Meldgaard, Morten
A1  - Fjeldsa, Jon
A1  - Shapiro, Beth
A1  - Hofreiter, Michael
A1  - Stewart, John R.
A1  - Gilbert, M. Thomas P.
A1  - Knapp, Michael
T1  - Demographic reconstruction from ancient DNA supports rapid extinction of the great auk
JF  - eLife
N2  - The great auk was once abundant and distributed across the North Atlantic. It is now extinct, having been heavily exploited for its eggs, meat, and feathers. We investigated the impact of human hunting on its demise by integrating genetic data, GPS-based ocean current data, and analyses of population viability. We sequenced complete mitochondrial genomes of 41 individuals from across the species' geographic range and reconstructed population structure and population dynamics throughout the Holocene. Taken together, our data do not provide any evidence that great auks were at risk of extinction prior to the onset of intensive human hunting in the early 16th century. In addition, our population viability analyses reveal that even if the great auk had not been under threat by environmental change, human hunting alone could have been sufficient to cause its extinction. Our results emphasise the vulnerability of even abundant and widespread species to intense and localised exploitation.
Y1  - 2019
U6  - https://doi.org/10.7554/eLife.47509
SN  - 2050-084X
VL  - 8
PB  - eLife Sciences Publications
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bröker, Katharine
A1  - Sinelnikov, Evgeny
A1  - Gustavus, Dirk
A1  - Schumacher, Udo
A1  - Pörtner, Ralf
A1  - Hoffmeister, Hans
A1  - Lüth, Stefan
A1  - Dammermann, Werner
T1  - Mass Production of Highly Active NK Cells for Cancer Immunotherapy in a GMP Conform Perfusion Bioreactor
JF  - Frontiers in Bioengineering and Biotechnology
N2  - NK cells have emerged as promising candidates for cancer immunotherapy, especially due to their ability to fight circulating tumor cells thereby preventing metastases formation. Hence several studies have been performed to generate and expand highly cytotoxic NK cells ex vivo, e.g., by using specific cytokines to upregulate both their proliferation and surface expression of distinct activating receptors. Apart from an enhanced activity, application of NK cells as immunotherapeutic agent further requires sufficient cell numbers and a high purity. All these parameters depend on a variety of different factors including the starting material, additives like cytokines as well as the culture system. Here we analyzed PBMC-derived NK cells of five anonymized healthy donors expanded under specific conditions in an innovative perfusion bioreactor system with respect to their phenotype, IFN gamma production, and cytotoxicity in vitro. Important features of the meander type bioreactors used here are a directed laminar flow of medium and control of relevant process parameters. Cells are cultivated under "steady state" conditions in perfusion mode. Our data demonstrate that expansion of CD3(+) T cell depleted PBMCs in our standardized system generates massive amounts of highly pure (>85%) and potent anticancer active NK cells. These cells express a variety of important receptors driving NK cell recruitment, adhesion as well as activation. More specifically, they express the chemokine receptors CXCR3, CXCR4, and CCR7, the adhesion molecules L-selectin, LFA-1, and VLA-4, the activating receptors NKp30, NKp44, NKp46, NKG2D, DNAM1, and CD16 as well as the death ligands TRAIL and Fas-L. Moreover, the generated NK cells show a strong IFN gamma expression upon cultivation with K562 tumor cells and demonstrate a high cytotoxicity toward leukemic as well as solid tumor cell lines in vitro. Altogether, these characteristics promise a high clinical potency of thus produced NK cells awaiting further evaluation.
KW  - natural killer cells (NK cells)
KW  - cytotoxicity
KW  - tumor immunity
KW  - immunotherapy
KW  - perfusion bioreactor
KW  - GMP
KW  - mass production process
Y1  - 2019
U6  - https://doi.org/10.3389/fbioe.2019.00194
SN  - 2296-4185
VL  - 7
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  -