@article{ValoriGreenDemoulinetal.2012, author = {Valori, Gherardo and Green, Lucie M. and Demoulin, Pascal and Vargas Dominguez, S. and van Driel-Gesztelyi, L. and Wallace, A. and Baker, Daniel N. and Fuhrmann, Marcel}, title = {Nonlinear force-free extrapolation of emerging flux with a global twist and serpentine fine structures}, series = {Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics}, volume = {278}, journal = {Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics}, number = {1}, publisher = {Springer}, address = {Dordrecht}, issn = {0038-0938}, doi = {10.1007/s11207-011-9865-8}, pages = {73 -- 97}, year = {2012}, abstract = {We study the flux emergence process in NOAA active region 11024, between 29 June and 7 July 2009, by means of multi-wavelength observations and nonlinear force-free extrapolation. The main aim is to extend previous investigations by combining, as much as possible, high spatial resolution observations to test our present understanding of small-scale (undulatory) flux emergence, whilst putting these small-scale events in the context of the global evolution of the active region. The combination of these techniques allows us to follow the whole process, from the first appearance of the bipolar axial field on the east limb, until the buoyancy instability could set in and raise the main body of the twisted flux tube through the photosphere, forming magnetic tongues and signatures of serpentine field, until the simplification of the magnetic structure into a main bipole by the time the active region reaches the west limb. At the crucial time of the main emergence phase high spatial resolution spectropolarimetric measurements of the photospheric field are employed to reconstruct the three-dimensional structure of the nonlinear force-free coronal field, which is then used to test the current understanding of flux emergence processes. In particular, knowledge of the coronal connectivity confirms the identity of the magnetic tongues as seen in their photospheric signatures, and it exemplifies how the twisted flux, which is emerging on small scales in the form of a sea-serpent, is subsequently rearranged by reconnection into the large-scale field of the active region. In this way, the multi-wavelength observations combined with a nonlinear force-free extrapolation provide a coherent picture of the emergence process of small-scale magnetic bipoles, which subsequently reconnect to form a large-scale structure in the corona.}, language = {en} } @article{ValoriDemoulinPariat2012, author = {Valori, Gherardo and Demoulin, Pascal and Pariat, E.}, title = {Comparing values of the relative magnetic helicity in finite volumes}, series = {Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics}, volume = {278}, journal = {Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics}, number = {2}, publisher = {Springer}, address = {Dordrecht}, issn = {0038-0938}, doi = {10.1007/s11207-012-9951-6}, pages = {347 -- 366}, year = {2012}, abstract = {Relative magnetic helicity, as a conserved quantity of ideal magnetohydrodynamics, has been highlighted as an important quantity to study in plasma physics. Due to its nonlocal nature, its estimation is not straightforward in both observational and numerical data. In this study we derive expressions for the practical computation of the gauge-independent relative magnetic helicity in three-dimensional finite domains. The derived expressions are easy to implement and rapid to compute. They are derived in Cartesian coordinates, but can be easily written in other coordinate systems. We apply our method to a numerical model of a force-free equilibrium containing a flux rope, and compare the results with those obtained employing known half-space equations. We find that our method requires a much smaller volume than half-space expressions to derive the full helicity content. We also prove that values of relative magnetic helicity of different magnetic fields can be compared with each other in the same sense as free-energy values can. Therefore, relative magnetic helicity can be meaningfully and directly compared between different datasets, such as those from different active regions, but also within the same dataset at different times. Typical applications of our formulae include the helicity computation in three-dimensional models of the solar atmosphere, e.g., coronal-field reconstructions by force-free extrapolation and discretized magnetic fields of numerical simulations.}, language = {en} } @article{UusiHeikkilaBoeckenhoffWolteretal.2012, author = {Uusi-Heikkila, Silva and Boeckenhoff, Linda and Wolter, Christian and Arlinghaus, Robert}, title = {Differential Allocation by Female Zebrafish (Danio rerio) to Different-Sized Males - An Example in a Fish Species Lacking Parental Care}, series = {PLOS ONE}, volume = {7}, journal = {PLOS ONE}, number = {10}, publisher = {PUBLIC LIBRARY SCIENCE}, address = {SAN FRANCISCO}, issn = {1932-6203}, doi = {10.1371/journal.pone.0048317}, pages = {7}, year = {2012}, abstract = {Organisms allocate resources to reproduction in response to the costs and benefits of current and future reproductive opportunities. According to the differential allocation hypothesis, females allocate more resources to high-quality males. We tested whether a fish species lacking parental care (zebrafish, Danio rerio) expresses male size-dependent differential allocation in monogamous spawning trials. In addition, we tested whether reproductive allocation by females is affected by previous experience of different-quality males, potentially indicating plasticity in mate choice. To that end, females were conditioned to large, small or random-sized males (controls) for 14 days to manipulate females\’ expectations of the future mate quality. Females showed a clear preference for large males in terms of spawning probability and clutch size independent of the conditioning treatment. However, when females experienced variation in male size (random-sized conditioning treatment) they discriminated less against small males compared to females conditioned to large and small males. This might suggest that differential allocation and size-dependent sexual selection is of less relevance in nature than revealed in the present laboratory study.}, language = {en} } @phdthesis{Uttamchand2012, author = {Uttamchand, Narendra Kumar}, title = {Shape-memory properties of magnetically active compositives based on multiphase polymer networks}, address = {Potsdam}, pages = {XI, 113 S.}, year = {2012}, language = {en} } @phdthesis{Urbach2012, author = {Urbach, Tina}, title = {What makes or breaks proactivity at work : how personal motives affect the evaluation of improvement suggestions}, address = {Potsdam}, pages = {226 S.}, year = {2012}, language = {en} } @article{UnuabonahElKhaiaryOluOwolabietal.2012, author = {Unuabonah, Emmanuel Iyayi and El-Khaiary, Mohammad I. and Olu-Owolabi, Bamidele I. and Adebowale, Kayode O.}, title = {Predicting the dynamics and performance of a polymer-clay based composite in a fixed bed system for the removal of lead (II) ion}, series = {Chemical engineering research and design}, volume = {90}, journal = {Chemical engineering research and design}, number = {8}, publisher = {Inst. of Electr. and Electronics Engineers}, address = {Rugby}, issn = {0263-8762}, doi = {10.1016/j.cherd.2011.11.009}, pages = {1105 -- 1115}, year = {2012}, abstract = {A polymer-clay based composite adsorbent was prepared from locally obtained kaolinite clay and polyvinyl alcohol. The composite adsorbent was used to remove lead (II) ions from aqueous solution in a fixed bed mode. The increase in bed height and initial metal ion concentration increased the adsorption capacity of lead (II) and the volume of aqueous solution treated at 50\% breakthrough. However, the adsorption capacity was reduced by almost 16.5\% with the simultaneous presence of Ca2+/Pb2+ and Na+/Pb2+ in the aqueous solution. Regeneration of the adsorbent with 0.1 M of HCl also reduced its adsorption capacity to 75.1\%. Adsorption of lead (II) ions onto the polymer-clay composite adsorbent in the presence of Na+ and Ca2+ electrolyte increased the rate of mass transfer, probably due to competition between cationic species in solution for adsorption sites. Regeneration further increased the rate of mass transfer as a result of reduced adsorption sites after the regeneration process. The length of the mass transfer zone was found to increase with increasing bed height but did not change with increasing the initial metal ion concentration. The models of Yoon-Nelson, Thomas, and Clark were found to give good fit to adsorption data. On the other hand, Bohart-Adams model was found to be a poor predictor for the column operation. The polymer-clay composite adsorbent has a good potential for the removal of lead (II) ions from highly polluted aqueous solutions.}, language = {en} } @article{UngruBlueherCoenenetal.2012, author = {Ungru, J. and Bl{\"u}her, M. and C{\"o}nen, M. and Raila, Jens and Boston, R. and Vervuert, I.}, title = {Effects of body weight reduction on blood adipokines and subcutaneous adipose tissue adipokine mRNA expression profiles in obese ponies}, series = {The veterinary record}, volume = {171}, journal = {The veterinary record}, number = {21}, publisher = {British Veterinary Association}, address = {London}, issn = {0042-4900}, doi = {10.1136/vr.100911}, pages = {528 -- +}, year = {2012}, abstract = {Fifteen obese ponies were used in a body weight (BW) reduction programme (BWRP, daily energy intake: 7.0-8.4 MJ/100 kg BW). A frequently sampled intravenous glucose tolerance test was used to assess insulin sensitivity. Subcutaneous adipose tissue biopsies of the tail head were obtained for mRNA gene expression profiles of adiponectin, retinol-binding protein 4 (RBP4), interleukin 6 (IL-6) and macrophage activation marker (CD68) before and after BWRP. Blood samples were analysed for serum leptin, serum RBP4 and plasma adiponectin. Significant BW losses occurred with 7 MJ DE/100 kg BW. Serum leptin and RBP4 were initially similar between insulin-resistant (IR) and insulin-sensitive (IS) ponies, and both significantly decreased during BWRP. Compared with IS ponies, IR ponies initially had significantly lower plasma adiponectin levels. At the beginning of BWRP, mRNA expression of RBP4, adiponectin, IL-6 and CD68 was similar between IR and IS ponies. Plasma adiponectin was strongly related to IR, whereas serum leptin and RBP4 were closely linked to adiposity, independent of insulin sensitivity. Adipose tissue mRNA expression profiles did not clearly reflect these differences. However, the role of subcutaneous adipose tissue in IR remains open.}, language = {en} } @misc{Ungelenk2012, author = {Ungelenk, Johannes}, title = {Narcissus and Echo}, number = {186}, issn = {1866-8380}, doi = {10.25932/publishup-59996}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-599966}, pages = {142}, year = {2012}, abstract = {George Eliot's late novel Daniel Deronda tackles big, fundamental political questions that radiate from the societal circumstances of the novel's production and reach deep into our present-day life. The novel critically analyses the capitalistic, morally flawed and standard-less English society and narrates the title hero's proto-Zionist mission to found a Jewish nation that re-establishes history, meaning and ethical values. This study attempts to trace the novel's two models of society and time by bringing them into resonance with the myth of Narcissus and Echo famously rendered by Ovid. The unloving, self-referential, visual Narcissus is read as the model for the capitalistic world of spectacle and speculation. Echo's loving, memory-bearing voice forms an important part in the construction of the sublating unity of the Jewish nation-to-come. Guided by this resonance between George Eliot's novel and Ovid's myth pieces of critical theory and philosophy are woven into the study's fabric. The resulting analysis dissects and deconstructs the novel's fascinating and highly complex patterns of conditions of possibility for the fabrication of the redeeming Jewish nation, the very same conditions that the novel presents as the conditions of possibility for narrating a meaningful story.}, language = {en} } @article{UllnerAresMorellietal.2012, author = {Ullner, E. and Ares, S. and Morelli, L. G. and Oates, A. C. and J{\"u}licher, F. and Nicola, E. and Heussen, R. and Whitmore, D. and Blyuss, K. and Fryett, M. and Zakharova, A. and Koseska, A. and Nene, N. R. and Zaikin, Alexei}, title = {Noise and oscillations in biological sysems multidisciplinary approach between experimental biology, theoretical modelling and synthetic biology}, series = {International journal of modern physics : B, Condensed matter physics, statistical physics, applied physics}, volume = {26}, journal = {International journal of modern physics : B, Condensed matter physics, statistical physics, applied physics}, number = {25}, publisher = {World Scientific}, address = {Singapore}, issn = {0217-9792}, doi = {10.1142/S0217979212460095}, pages = {12}, year = {2012}, abstract = {Rapid progress of experimental biology has provided a huge flow of quantitative data, which can be analyzed and understood only through the application of advanced techniques recently developed in theoretical sciences. On the other hand, synthetic biology enabled us to engineer biological models with reduced complexity. In this review we discuss that a multidisciplinary approach between this sciences can lead to deeper understanding of the underlying mechanisms behind complex processes in biology. Following the mini symposia "Noise and oscillations in biological systems" on Physcon 2011 we have collected different research examples from theoretical modeling, experimental and synthetic biology.}, language = {en} } @article{UhligMadaboosiSchmidtetal.2012, author = {Uhlig, Katja and Madaboosi, Narayanan and Schmidt, Stephan and J{\"a}ger, Magnus S. and Rose, J{\"u}rgen and Duschl, Claus and Volodkin, Dmitry V.}, title = {3d localization and diffusion of proteins in polyelectrolyte multilayers}, series = {Soft matter}, volume = {8}, journal = {Soft matter}, number = {47}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c2sm26500a}, pages = {11786 -- 11789}, year = {2012}, abstract = {The interaction of diverse biomaterials with surfaces is more crucial than ever for biomedical applications to ensure efficiency and reproducibility. Very interesting surface materials are micrometer-thick polyelectrolyte multilayers. Not only their surface but also the bulk can be loaded with biomaterials like proteins or DNA for various purposes. Therefore, we established a method to analyze the lateral and vertical distribution of fluorescently labelled proteins of various size and charge in polyelectrolyte films composed of poly(L-lysine) and hyaluronic acid by confocal laser scanning microscopy. This approach enables us to measure the diffusion coefficients of the proteins via fluorescence recovery after photobleaching as a function of their vertical position in the film and facilitates the understanding of molecular interactions in the film with a high resolution in both space and time. As a result, we confirm that protein loading in the film is driven by electrostatic interactions - uncharged dextran molecules of 10 and 500 kDa do not diffuse into the film. Proteins of different sizes (3-11 nm) can diffuse relatively fast (D = 2-4 mm(2) s(-1)) independent of their net charge, indicating complex interpolymer interactions. This approach is a new powerful experimental tool to design the polyelectrolyte multilayers for bio-applications by finding a relationship between intermolecular interactions and mobility and availability of biomolecules to biological samples (e.g. cells) or detection units (e.g. biosensors).}, language = {en} }