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573 result(s) for "Schmelling, M."
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What is holding back cyanobacterial research and applications? A survey of the cyanobacterial research community
Cyanobacteria are a diverse group of prokaryotic organisms that have been the subject of intense basic research, resulting in a wealth of knowledge about fundamental cellular processes such as photosynthesis. However, the translation of that research towards industry-relevant applications is still limited. To understand the reasons for this contradictory situation, we conducted a quantitative survey among researchers in the cyanobacterial community, a set of individual interviews with established researchers, and a literature analysis. Our results show that the community seems to be committed to embracing cyanobacterial diversity and promoting collaboration. Additionally, participants expressed a strong desire to develop standardized protocols for research and establish larger consortia to accelerate progress. The results of the survey highlight the need for a more integrated approach to cyanobacterial research that encompasses both basic and applied aspects. Based on the survey and interview results as well as our literature analysis, we highlight areas for potential improvement, strategies to enhance cyanobacterial research, and open questions that demand further exploration. Addressing these challenges should accelerate the development of industrial applications based on cyanobacterial research. Cyanobacteria have been the subject of intense basic research, but translation towards industrial applications remains limited. Here, Schmelling and Bross conduct a survey among researchers in the cyanobacterial community, as well as a literature analysis, to highlight potential strategies to enhance cyanobacterial research and accelerate the development of industrial applications.
Two KaiABC systems control circadian oscillations in one cyanobacterium
The circadian clock of cyanobacteria, which predicts daily environmental changes, typically includes a standard oscillator consisting of proteins KaiA, KaiB, and KaiC. However, several cyanobacteria have diverse Kai protein homologs of unclear function. In particular, Synechocystis sp. PCC 6803 harbours, in addition to a canonical kaiABC gene cluster (named kaiAB1C1 ), two further kaiB and kaiC homologs ( kaiB2 , kaiB3 , kaiC2 , kaiC3 ). Here, we identify a chimeric KaiA homolog, named KaiA3, encoded by a gene located upstream of kaiB3 . At the N-terminus, KaiA3 is similar to response-regulator receiver domains, whereas its C-terminal domain resembles that of KaiA. Homology analysis shows that a KaiA3-KaiB3-KaiC3 system exists in several cyanobacteria and other bacteria. Using the Synechocystis sp. PCC 6803 homologs, we observe circadian oscillations in KaiC3 phosphorylation in vitro in the presence of KaiA3 and KaiB3. Mutations of kaiA3 affect KaiC3 phosphorylation, leading to growth defects under both mixotrophic and chemoheterotrophic conditions. KaiC1 and KaiC3 exhibit phase-locked free-running phosphorylation rhythms. Deletion of either system (∆ kaiAB1C1 or ∆ kaiA3B3C3 ) alters the period of the cellular backscattering rhythm. Furthermore, both oscillators are required to maintain high-amplitude, self-sustained backscatter oscillations with a period of approximately 24 h, indicating their interconnected nature. The cyanobacterial circadian clock typically includes a standard oscillator consisting of proteins KaiA, KaiB and KaiC, but some cyanobacteria have additional homologous proteins of unclear function. Here, the authors show that a KaiABC homolog system contributes, together with the canonical oscillator, to the control of circadian rhythms in the model cyanobacterium Synechocystis sp. PCC 6803.
Sub-TeV hadronic interaction model differences and their impact on air showers
In the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions for post-first interaction and ground-level particle spectra from cosmic ray induced air showers. These differences generate an important source of systematic uncertainty in their experimental use. We investigate the nature and impact of model uncertainties through a simultaneous analysis of ground level particles and first interaction scenarios. We focus on air shower primaries with energies close to the transition between high and low energy hadronic interaction models, where the dissimilarities have been shown to be the largest and well within the range of accelerator measurements. Interaction models are shown to diverge as several shower scenarios are compared, reflecting intrinsic differences in the model theoretical frameworks. Finally, we discuss the importance of interactions in the energy regime where the switching between models occurs (<1 TeV) and the effect of the choice of model on the number of hadronic interactions within cosmic ray induced air showers of higher energies.
Minimal tool set for a prokaryotic circadian clock
Background Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating. However, interaction and function of non-cyanobacterial Kai-proteins as well as homologous input and output components remain mainly unclear. Results Using a universal BLAST analyses, we identified putative KaiC-based timing systems in organisms outside as well as variations within Cyanobacteria. A systematic analyses of publicly available microarray data elucidated interesting variations in circadian gene expression between different cyanobacterial strains, which might be correlated to the diversity of genome encoded clock components. Based on statistical analyses of co-occurrences of the clock components homologous to Synechococcus elongatus PCC 7942, we propose putative networks of reduced and fully functional clock systems. Further, we studied KaiC sequence conservation to determine functionally important regions of diverged KaiC homologs. Biochemical characterization of exemplary cyanobacterial KaiC proteins as well as homologs from two thermophilic Archaea demonstrated that kinase activity is always present. However, a KaiA-mediated phosphorylation is only detectable in KaiC1 orthologs. Conclusion Our analysis of 11,264 genomes clearly demonstrates that components of the Synechococcus elongatus PCC 7942 circadian clock are present in Bacteria and Archaea. However, all components are less abundant in other organisms than Cyanobacteria and KaiA, Pex, LdpA, and CdpA are only present in the latter. Thus, only reduced KaiBC-based or even simpler, solely KaiC-based timing systems might exist outside of the cyanobacterial phylum, which might be capable of driving diurnal oscillations.
Heavy-flavor production and medium properties in high-energy nuclear collisions --What next?
. Open and hidden heavy-flavor physics in high-energy nuclear collisions are entering a new and exciting stage towards reaching a clearer understanding of the new experimental results with the possibility to link them directly to the advancement in lattice Quantum Chromo-Dynamics (QCD). Recent results from experiments and theoretical developments regarding open and hidden heavy-flavor dynamics have been debated at the Lorentz Workshop Tomography of the Quark-Gluon Plasma with Heavy Quarks , which was held in October 2016 in Leiden, The Netherlands. In this contribution, we summarize identified common understandings and developed strategies for the upcoming five years, which aim at achieving a profound knowledge of the dynamical properties of the quark-gluon plasma.
Test of lepton universality with B0 → K0ℓ+ℓ− decays
A bstract A test of lepton universality, performed by measuring the ratio of the branching fractions of the B 0 → K *0 μ + μ − and B 0 → K *0 e + e − decays, R K * 0 , is presented. The K *0 meson is reconstructed in the final state K + π − , which is required to have an invariant mass within 100 MeV /c 2 of the known K * (892) 0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb −1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2 , to be R K * 0 = 0.66 − + 0.07 0.11 stat ± 0.03 syst f o r 0.045 < q 2 < 1.1 GeV 2 / c 4 , 0.69 − + 0.07 0.11 stat ± 0.05 syst f o r 1.1 < q 2 < 6.0 GeV 2 / c 4 . The corresponding 95.4% confidence level intervals are [0 . 52 , 0 . 89] and [0 . 53 , 0 . 94]. The results, which represent the most precise measurements of R K * 0 to date, are compatible with the Standard Model expectations at the level of 2.1–2.3 and 2.4–2.5 standard deviations in the two q 2 regions, respectively.
Angular analysis of the B0 → K0μ+μ− decay using 3 fb−1 of integrated luminosity
A bstract An angular analysis of the B 0 → K *0 (→ K + π − ) μ + μ − decay is presented. The dataset corresponds to an integrated luminosity of 3.0 fb −1 of pp collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine CP -averaged observables and CP asymmetries, taking account of possible contamination from decays with the K + π − system in an S-wave configuration. The angular observables and their correlations are reported in bins of q 2 , the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for q 2 -dependent decay amplitudes in the region 1.1 < q 2 < 6.0 GeV 2 / c 4 , the zero-crossing points of several angular observables are computed. A global fit is performed to the complete set of CP -averaged observables obtained from the maximum likelihood fit. This fit indicates differences with predictions based on the Standard Model at the level of 3.4 standard deviations. These differences could be explained by contributions from physics beyond the Standard Model, or by an unexpectedly large hadronic effect that is not accounted for in the Standard Model predictions.
Differential branching fractions and isospin asymmetries of B → K()μ+μ− decays
A bstract The isospin asymmetries of B → Kμ + μ − and B → K * μ + μ − decays and the partial branching fractions of the B 0 → K 0 μ + μ − , B + → K + μ + μ − and B + → K *+ μ + μ − decays are measured as functions of the dimuon mass squared, q 2 . The data used correspond to an integrated luminosity of 3 fb −1 from proton-proton collisions collected with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV in 2011 and 2012, respectively. The isospin asymmetries are both consistent with the Standard Model expectations. The three measured branching fractions favour lower values than their respective theoretical predictions, however they are all individually consistent with the Standard Model.
Measurements of prompt charm production cross-sections in pp collisions at s=13 TeV
A bstract Production cross-sections of prompt charm mesons are measured with the first data from pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 4.98 ± 0.19 pb −1 collected by the LHCb experiment. The production cross-sections of D 0 , D + , D s + , and D *+ mesons are measured in bins of charm meson transverse momentum, p T , and rapidity, y , and cover the range 0 < p T < 15GeV/c and 2.0 < y < 4.5. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of 1 < p T < 8 GeV/c are found to be σ pp → D 0 X = 2460 ± 3 ± 130 μ b σ pp → D + X = 1000 ± 3 ± 110 μ b σ pp → D s + X = 460 ± 13 ± 100 μ b σ pp → D ∗ + X = 880 ± 5 ± 140 μ b where the uncertainties are due to statistical and systematic uncertainties, respectively.
Angular analysis and differential branching fraction of the decay Bs0 → ϕμ+μ
A bstract An angular analysis and a measurement of the differential branching fraction of the decay B s 0  →  ϕμ + μ − are presented, using data corresponding to an integrated luminosity of 3 . 0 fb −1 of pp collisions recorded by the LHCb experiment at s = 7 and 8 TeV. Measurements are reported as a function of q 2 , the square of the dimuon invariant mass and results of the angular analysis are found to be consistent with the Standard Model. In the range 1 < q 2 < 6 GeV 2 /c 4 , where precise theoretical calculations are available, the differential branching fraction is found to be more than 3 σ below the Standard Model predictions.