@article{BlomeyerBuchmannLascorzetal.2013, author = {Blomeyer, Dorothea and Buchmann, Arlette F. and Lascorz, Jesus and Zimmermann, Ulrich S. and Esser, G{\"u}nter and Desrivieres, Sylvane and Schmidt, Martin H. and Banaschewski, Tobias and Schumann, Gunter and Laucht, Manfred}, title = {Association of PER2 genotype and stressful life events with alcohol drinking in young adults}, series = {PLoS one}, volume = {8}, journal = {PLoS one}, number = {3}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0059136}, pages = {7}, year = {2013}, abstract = {Background: Clock genes govern circadian rhythms and shape the effect of alcohol use on the physiological system. Exposure to severe negative life events is related to both heavy drinking and disturbed circadian rhythmicity. The aim of this study was 1) to extend previous findings suggesting an association of a haplotype tagging single nucleotide polymorphism of PER2 gene with drinking patterns, and 2) to examine a possible role for an interaction of this gene with life stress in hazardous drinking. Methods: Data were collected as part of an epidemiological cohort study on the outcome of early risk factors followed since birth. At age 19 years, 268 young adults (126 males, 142 females) were genotyped for PER2 rs56013859 and were administered a 45-day alcohol timeline follow-back interview and the Alcohol Use Disorders Identification Test (AUDIT). Life stress was assessed as the number of severe negative life events during the past four years reported in a questionnaire and validated by interview. Results: Individuals with the minor G allele of rs56013859 were found to be less engaged in alcohol use, drinking at only 72\% of the days compared to homozygotes for the major A allele. Moreover, among regular drinkers, a gene x environment interaction emerged (p = .020). While no effects of genotype appeared under conditions of low stress, carriers of the G allele exhibited less hazardous drinking than those homozygous for the A allele when exposed to high stress. Conclusions: These findings may suggest a role of the circadian rhythm gene PER2 in both the drinking patterns of young adults and in moderating the impact of severe life stress on hazardous drinking in experienced alcohol users. However, in light of the likely burden of multiple tests, the nature of the measures used and the nominal evidence of interaction, replication is needed before drawing firm conclusions.}, language = {en} } @article{KuptsovKuznetsovPikovskij2013, author = {Kuptsov, Pavel V. and Kuznetsov, Sergey P. and Pikovskij, Arkadij}, title = {Hyperbolic chaos at blinking coupling of noisy oscillators}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {87}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {3}, publisher = {American Physical Society}, address = {College Park}, issn = {1539-3755}, doi = {10.1103/PhysRevE.87.032912}, pages = {7}, year = {2013}, abstract = {We study an ensemble of identical noisy phase oscillators with a blinking mean-field coupling, where onecluster and two-cluster synchronous states alternate. In the thermodynamic limit the population is described by a nonlinear Fokker-Planck equation. We show that the dynamics of the order parameters demonstrates hyperbolic chaos. The chaoticity manifests itself in phases of the complex mean field, which obey a strongly chaotic Bernoulli map. Hyperbolicity is confirmed by numerical tests based on the calculations of relevant invariant Lyapunov vectors and Lyapunov exponents. We show how the chaotic dynamics of the phases is slightly smeared by finite-size fluctuations. DOI: 10.1103/PhysRevE.87.032912}, language = {en} } @article{KomarovPikovskij2013, author = {Komarov, Maxim and Pikovskij, Arkadij}, title = {Dynamics of multifrequency oscillator communities}, series = {Physical review letters}, volume = {110}, journal = {Physical review letters}, number = {13}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.110.134101}, pages = {5}, year = {2013}, abstract = {We consider a generalization of the Kuramoto model of coupled oscillators to the situation where communities of oscillators having essentially different natural frequencies interact. General equations describing possible resonances between the communities' frequencies are derived. The simplest situation of three resonantly interacting groups is analyzed in detail. We find conditions for the mutual coupling to promote or suppress synchrony in individual populations and present examples where the interaction between communities leads to their synchrony or to a partially asynchronous state or to a chaotic dynamics of order parameters. DOI: 10.1103/PhysRevLett.110.134101}, language = {en} } @article{PingelNeher2013, author = {Pingel, P. and Neher, Dieter}, title = {Comprehensive picture of p-type doping of P3HT with the molecular acceptor F(4)TCNQ}, series = {Physical review : B, Condensed matter and materials physics}, volume = {87}, journal = {Physical review : B, Condensed matter and materials physics}, number = {11}, publisher = {American Physical Society}, address = {College Park}, issn = {1098-0121}, doi = {10.1103/PhysRevB.87.115209}, pages = {9}, year = {2013}, abstract = {By means of optical spectroscopy, Kelvin probe, and conductivity measurements, we study the p-type doping of the donor polymer poly(3-hexylthiophene), P3HT, with the molecular acceptor tetrafluorotetracyanoquin-odimethane, F(4)TCNQ, covering a broad range of molar doping ratios from the ppm to the percent regime. Thorough quantitative analysis of the specific near-infrared absorption bands of ionized F(4)TCNQ reveals that almost every F(4)TCNQ dopant undergoes integer charge transfer with a P3HT site. However, only about 5\% of these charge carrier pairs are found to dissociate and contribute a free hole for electrical conduction. The nonlinear behavior of the conductivity on doping ratio is rationalized by a numerical mobility model that accounts for the broadening of the energetic distribution of transport sites by the Coulomb potentials of ionized F(4)TCNQ dopants. DOI: 10.1103/PhysRevB.87.115209}, language = {en} } @article{VossBolhuisFeweretal.2013, author = {Voss, Bj{\"o}rn and Bolhuis, Henk and Fewer, David P. and Kopf, Matthias and M{\"o}ke, Fred and Haas, Fabian and El-Shehawy, Rehab and Hayes, Paul and Bergman, Birgitta and Sivonen, Kaarina and Dittmann-Th{\"u}nemann, Elke and Scanlan, Dave J. and Hagemann, Martin and Stal, Lucas J. and Hess, Wolfgang R.}, title = {Insights into the physiology and ecology of the brackish-water-adapted cyanobacterium nodularia spumigena CCY9414 based on a genome-transcriptome analysis}, series = {PLoS one}, volume = {8}, journal = {PLoS one}, number = {3}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0060224}, pages = {22}, year = {2013}, abstract = {Nodularia spumigena is a filamentous diazotrophic cyanobacterium that dominates the annual late summer cyanobacterial blooms in the Baltic Sea. But N. spumigena also is common in brackish water bodies worldwide, suggesting special adaptation allowing it to thrive at moderate salinities. A draft genome analysis of N. spumigena sp. CCY9414 yielded a single scaffold of 5,462,271 nucleotides in length on which genes for 5,294 proteins were annotated. A subsequent strand-specific transcriptome analysis identified more than 6,000 putative transcriptional start sites (TSS). Orphan TSSs located in intergenic regions led us to predict 764 non-coding RNAs, among them 70 copies of a possible retrotransposon and several potential RNA regulators, some of which are also present in other N2-fixing cyanobacteria. Approximately 4\% of the total coding capacity is devoted to the production of secondary metabolites, among them the potent hepatotoxin nodularin, the linear spumigin and the cyclic nodulapeptin. The transcriptional complexity associated with genes involved in nitrogen fixation and heterocyst differentiation is considerably smaller compared to other Nostocales. In contrast, sophisticated systems exist for the uptake and assimilation of iron and phosphorus compounds, for the synthesis of compatible solutes, and for the formation of gas vesicles, required for the active control of buoyancy. Hence, the annotation and interpretation of this sequence provides a vast array of clues into the genomic underpinnings of the physiology of this cyanobacterium and indicates in particular a competitive edge of N. spumigena in nutrient-limited brackish water ecosystems.}, language = {en} } @article{KarpuzCevikKoppitzetal.2013, author = {Karpuz, Eylem Guzel and Cevik, Ahmet Sinan and Koppitz, J{\"o}rg and Cangul, Ismail Naci}, title = {Some fixed-point results on (generalized) Bruck-Reilly *-extensions of monoids}, series = {Fixed point theory and applications}, journal = {Fixed point theory and applications}, number = {3}, publisher = {Springer}, address = {Cham}, issn = {1687-1812}, doi = {10.1186/1687-1812-2013-78}, pages = {9}, year = {2013}, abstract = {In this paper, we determine necessary and sufficient conditions for Bruck-Reilly and generalized Bruck-Reilly *-extensions of arbitrary monoids to be regular, coregular and strongly pi-inverse. These semigroup classes have applications in various field of mathematics, such as matrix theory, discrete mathematics and p-adic analysis (especially in operator theory). In addition, while regularity and coregularity have so many applications in the meaning of boundaries (again in operator theory), inverse monoids and Bruck-Reilly extensions contain a mixture fixed-point results of algebra, topology and geometry within the purposes of this journal.}, language = {en} } @article{CostaFoersterdeAraujoetal.2013, author = {Costa, Alexandre Cunha and F{\"o}rster, Saskia and de Araujo, Jose Carlos and Bronstert, Axel}, title = {Analysis of channel transmission losses in a dryland river reach in north-eastern Brazil using streamflow series, groundwater level series and multi-temporal satellite data}, series = {Hydrological processes}, volume = {27}, journal = {Hydrological processes}, number = {7}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1099-1085}, doi = {10.1002/hyp.9243}, pages = {1046 -- 1060}, year = {2013}, abstract = {Scarcity of hydrological data, especially streamflow discharge and groundwater level series, restricts the understanding of channel transmission losses (TL) in drylands. Furthermore, the lack of information on spatial river dynamics encompasses high uncertainty on TL analysis in large rivers. The objective of this study was to combine the information from streamflow and groundwater level series with multi-temporal satellite data to derive a hydrological concept of TL for a reach of the Middle Jaguaribe River (MJR) in semi-arid north-eastern Brazil. Based on this analysis, we proposed strategies for its modelling and simulation. TL take place in an alluvium, where river and groundwater can be considered to be hydraulically connected. Most losses certainly infiltrated only through streambed and levees and not through the flood plains, as could be shown by satellite image analysis. TL events whose input river flows were smaller than a threshold did not reach the outlet of the MJR. TL events whose input flows were higher than this threshold reached the outlet losing on average 30\% of their input. During the dry seasons (DS) and at the beginning of rainy seasons (DS/BRS), no river flow is expected for pre-events, and events have vertical infiltration into the alluvium. At the middle and the end of the rainy seasons (MRS/ERS), river flow sustained by base flow occurs before/after events, and lateral infiltration into the alluvium plays a major role. Thus, the MJR shifts from being a losing river at DS/BRS to become a losing/gaining (mostly losing) river at MRS/ERS. A model of this system has to include the coupling of river and groundwater flow processes linked by a leakage approach.}, language = {en} } @article{DodooBalzerHugeletal.2013, author = {Dodoo, Samuel and Balzer, Bizan N. and Hugel, Thorsten and Laschewsky, Andr{\´e} and von Klitzing, Regine}, title = {Effect of ionic strength and layer number on swelling of polyelectrolyte multilayers in water vapour}, series = {Soft materials}, volume = {11}, journal = {Soft materials}, number = {2}, publisher = {Taylor \& Francis Group}, address = {Philadelphia}, issn = {1539-445X}, doi = {10.1080/1539445X.2011.607203}, pages = {157 -- 164}, year = {2013}, abstract = {The swelling behavior of polyelectrolyte multilayers (PEMs) of poly(sodium-4 styrene sulfonate) (PSS) and poly(diallyl dimethyl ammonium chloride) (PDADMAC) prepared from aqueous solution of 0.1 M and 0.5 M NaCl are investigated by ellipsometry and Atomic Force Microscopy (AFM). From 1 double-layer up to 4 double-layers of 0.1 M NaCl, the amount of swelling water in the PEMs decreases with increasing number of adsorbed double layers due to an increase in polyelectrolyte density as a result of the attraction between the positively charged outermost PDADMAC layer and the Si substrate. From 6 double layers to 30 double layers, the attraction is reduced due to a much larger distance between substrate and outermost layer leading to a much lower polyelectrolyte density and higher swelling water. In PEMs prepared from aqueous solution of 0.5 M NaCl, the amount of water constantly increases which is related to a monotonically decreasing polyelectrolyte density with increasing number of polyelectrolyte layers. Studies of the surface topology also indicate a transition from a more substrate affected interphase behavior to a continuum properties of the polyelectrolyte multilayers. The threshold for the transition from interphase to continuum behavior depends on the preparation conditions of the PEM.}, language = {en} } @article{AndresGohlkeBroekeretal.2013, author = {Andres, Dorothee and Gohlke, Ulrich and Br{\"o}ker, Nina Kristin and Schulze, Stefan and Rabsch, Wolfgang and Heinemann, Udo and Barbirz, Stefanie and Seckler, Robert}, title = {An essential serotype recognition pocket on phage P22 tailspike protein forces Salmonella enterica serovar Paratyphi A O-antigen fragments to bind as nonsolution conformers}, series = {Glycobiology}, volume = {23}, journal = {Glycobiology}, number = {4}, publisher = {Oxford Univ. Press}, address = {Cary}, issn = {0959-6658}, doi = {10.1093/glycob/cws224}, pages = {486 -- 494}, year = {2013}, abstract = {Bacteriophage P22 recognizes O-antigen polysaccharides of Salmonella enterica subsp. enterica (S.) with its tailspike protein (TSP). In the serovars S. Typhimurium, S. Enteritidis, and S. Paratyphi A, the tetrasaccharide repeat units of the respective O-antigens consist of an identical main chain trisaccharide but different 3,6-dideoxyhexose substituents. Here, the epimers abequose, tyvelose and paratose determine the specific serotype. P22 TSP recognizes O-antigen octasaccharides in an extended binding site with a single 3,6-dideoxyhexose binding pocket. We have isolated S. Paratyphi A octasaccharides which were not available previously and determined the crystal structure of their complex with P22 TSP. We discuss our data together with crystal structures of complexes with S. Typhimurium and S. Enteritidis octasaccharides determined earlier. Isothermal titration calorimetry showed that S. Paratyphi A octasaccharide binds P22 TSP less tightly, with a difference in binding free energy of similar to 7 kJ mol(-1) at 20 degrees C compared with S. Typhimurium and S. Enteritidis octasaccharides. Individual protein-carbohydrate contacts were probed by amino acid replacements showing that the dideoxyhexose pocket contributes to binding of all three serotypes. However, S. Paratyphi A octasaccharides bind in a conformation with an energetically unfavorable phi/epsilon glycosidic bond angle combination. In contrast, octasaccharides from the other serotypes bind as solution-like conformers. Two water molecules are conserved in all P22 TSP complexes with octasaccharides of different serotypes. They line the dideoxyhexose binding pocket and force the S. Paratyphi A octasaccharides to bind as nonsolution conformers. This emphasizes the role of solvent as part of carbohydrate binding sites.}, language = {en} } @article{RomeroVianaKienelWilkesetal.2013, author = {Romero-Viana, Lidia and Kienel, Ulrike and Wilkes, Heinz and Sachse, Dirk}, title = {Growth-dependent hydrogen isotopic fractionation of algal lipid biomarkers in hypersaline Isabel Lake (Mexico)}, series = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, volume = {106}, journal = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, number = {4}, publisher = {Elsevier}, address = {Oxford}, issn = {0016-7037}, doi = {10.1016/j.gca.2012.12.017}, pages = {490 -- 500}, year = {2013}, abstract = {In this study, we evaluated the potential of the hydrogen isotopic composition of algal lipid biomarkers as a proxy for past hydroclimatic variability in hypersaline Isabel Lake, Mexico (Eastern Pacific). We compared rainfall variability recorded in the region over the last 65 years with changes in delta D values of the most abundant compounds preserved in the uppermost 16 cm of lake sediment. Changes in delta D values of the 1,15-C-32 diol (delta D-diol), a specific biomarker of algal populations, were related to rainfall variability; specifically, n-alkyl diols were more deuterium-enriched (depleted) during wetter (drier) periods. Strikingly, neither the magnitude of lipid biomarker isotopic changes over interannual timescales (of up to 70-80 parts per thousand) nor the direction of that variability can be explained by changes in delta D values of the water source or salinity fluctuations (approximately 30 on the practical salinity scale) controlled by seasonal rainfall. However, changes in sedimentary biomarker composition, higher total organic carbon content and less negative delta C-13 values of the 1,15-C-32 diol indicate enhanced algal growth during wetter periods. We find that these conditions result in less negative delta D values of n-alkyl diols. We hypothesize that due to higher lipid demand during enhanced algal growth, an increasing proportion of hydrogen for lipid synthesis is derived from the cytosol via oxidation of polysaccharides, which may cause a deuterium enrichment of the acetogenic compounds. This study has significant implications for paleohydrological reconstructions using algal lipid delta D values, particularly in highly seasonal environments such as Isabel Lake. In such environments, delta D values of specific algal lipid biomarkers may not record the full seasonal cycle in source water delta D but appear to be mainly controlled by the physiological state of algal populations. Our data provide the first evidence that changes in D/H fractionation due to algal growth conditions can be recorded in sediments. For paleoclimate reconstructions in such environments, algal growth conditions should be constrained with additional proxy data (delta C-13 values of the same biomarkers), as the net D/H fractionation between water and lipids may not have been constant over time.}, language = {en} }