1,443 research outputs found
The non-linear evolution of bispectrum from the scale-free N-body simulation
We have accurately measured the bispectrum for four scale-free models of
structure formation with the spectral index , 0, -1, and -2. The
measurement is based on a new method that can effectively eliminate the alias
and numerical artifacts, and reliably extend the analysis into the strongly
non-linear regime. The work makes use of a set of state-of-the art N-body
simulations that have significantly increased the resolution range compared
with the previous studies on the subject. With these measured results, we
demonstrated that the measured bispectrum depends on the shape and size of
-triangle even in the strongly nonlinear regime. It increases with
wavenumber and decreases with the spectral index. These results are in contrast
with the hypothesis that the reduced bispectrum is a constant in the strongly
non-linear regime. We also show that the fitting formula of Scoccimarro &
Frieman (1999) does not describe our simulation results well (with a typical
error about 40 percent). In the end, we present a new fitting formula for the
reduced bispectrum that is valid for with a typical error of
10 percent only.Comment: 33 pages, including 1 table, 14 figures, accepted by Ap
Accessing the Next Generation of Synthetic MusselâGlue Polymers via MusselâInspired Polymerization
The formation of cysteinyldopa as biogenic connectivity in proteins is used to inspire a chemical pathway toward mussel-adhesive mimics. The mussel-inspired polymerization (MIPoly) exploits the chemically diverse family of bisphenol monomers that is oxidizable with 2-iodoxybenzoic acid to give bisquinones. Those react at room temperature with dithiols in Michael-type polyadditions, which leads to polymers with thiolâcatechol connectivities (TCC). A set of TCC polymers proved adhesive behavior even on challenging poly(propylene) substrates, where they compete with commercial epoxy resins in dry adhesive strength. MIPoly promises facile scale up and exhibits high modularity to tailor adhesives, as proven on a small library where one candidate showed wet adhesion on aluminum substrates in both water and sea water models.Verband der Chemischen Industrie
http://dx.doi.org/10.13039/100007215Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659Peer Reviewe
Three-point correlation function of galaxy clusters in cosmological models: a strong dependence on triangle shape
In this paper, we use large \pppm N-body simulations to study the three-point correlation function \zeta of clusters in two theoretical models. The first model (LCDM) is a low-density flat model of \Omega_0=0.3, \Lambda_0=0.7 and h=0.75, and the second model (PIM) is an Einstein-de-Sitter model with its linear power spectrum obtained from observations. We found that the scaled function Q(r,u,v), which is defined as the ratio of \zeta (r, ru, ru+rv) to the hierarchical sum \xi (r)\xi (ru)+ \xi (ru) \xi (ru+rv) +\xi (ru+rv)\xi (r) (where \xi is the two-point correlation function of clusters), depends weakly on r and u, but very strongly on v. Q(r,u,v) is about 0.2 at v=0.1 and 1.8 at v=0.9. A model of Q(r,u,v)=\Theta 10^{1.3v^2} can fit the data of \zeta very nicely with \Theta\approx 0.14. This model is found to be universal for the LCDM clusters and for the PIM clusters. Furthermore, Q(r,u,v) is found to be insensitive to the cluster richness. We have compared our N-body results with simple analytical theories of cluster formation, like the peak theories or the local maxima theories. We found that these theories do not provide an adequate description for the three-point function of clusters. We have also examined the observational data of \zeta presently available, and have not found any contradiction between the observations and our model predictions. The v-dependence of q in a projected catalogue of clusters is shown to be much weaker than the v-dependence of Q found in the three-dimensional case. It would be important to search for the v-dependence of Q in redshift samples of rich clusters
Peptide-Assisted Design of Precision Polymer Sequences
Functional sequences of monodisperse, sequenceâdefined oligo(amideâurethane)s are designed based on a peptide sequence as blueprint. The translation of a discrete sideâchain functionality sequence from a known peptideâbased solubilizer of the photosensitizer metaâtetra(hydroxyphenyl)âchlorin, into a nonâpeptidic precision polymer backbone is demonstrated. The resulting peptidomimetic precision polymers retain the functions of the parent peptide sequence, showing analogues sensitivity toward single monomer mutations/exchanges and even exceeding the parent peptide equivalent by reaching up to 69% higher payload capacities and more favored release kinetics.Peer Reviewe
Function of a Novel Checkpoint Protein in the Germ Line
Successful reproduction of Saccharomyces cerevisiae relies on the organismâs ability to complete the meiotic cell cycle and produce viable gametes. Zip1 is a protein that constitutes the central component of a protein structure that connects homologous chromosomes known as the synaptonemal complex. Zip1 is important for progression through the meiotic cell cycle. The C terminus of the coiled-coil Zip 1 protein is responsible for localization to the axes of the chromosomes. An internal deletion near the C terminus of Zip1, called zip1-c1, yields a stronger meiotic arrest than a mutation where Zip1 is completely deleted. The more efficient meiotic progression in a Zip1 deletion mutation versus the zip1-c1 mutant suggests that zip1-c1 prevents an alternative pathway of meiotic progression. A genomic screen of the Nasmyth genomic library revealed candidate plasmids N5 and N89 containing yeast genes which, when overexpressed, increase spore viability and bypass meiotic arrest in the zip1-c1 mutant. This has implications that the genes on the overexpression plasmids serve some function in correcting mistakes in meiosis when Zip1 is mutated.https://engagedscholarship.csuohio.edu/u_poster_2013/1014/thumbnail.jp
A cosmological model in Weyl-Cartan spacetime
We present a cosmological model for early stages of the universe on the basis
of a Weyl-Cartan spacetime. In this model, torsion and
nonmetricity are proportional to the vacuum polarization.
Extending earlier work of one of us (RT), we discuss the behavior of the cosmic
scale factor and the Weyl 1-form in detail. We show how our model fits into the
more general framework of metric-affine gravity (MAG).Comment: 19 pages, 5 figures, typos corrected, uses IOP style fil
Complex Systems Science: Dreams of Universality, Reality of Interdisciplinarity
Using a large database (~ 215 000 records) of relevant articles, we
empirically study the "complex systems" field and its claims to find universal
principles applying to systems in general. The study of references shared by
the papers allows us to obtain a global point of view on the structure of this
highly interdisciplinary field. We show that its overall coherence does not
arise from a universal theory but instead from computational techniques and
fruitful adaptations of the idea of self-organization to specific systems. We
also find that communication between different disciplines goes through
specific "trading zones", ie sub-communities that create an interface around
specific tools (a DNA microchip) or concepts (a network).Comment: Journal of the American Society for Information Science and
Technology (2012) 10.1002/asi.2264
Antimicrobial Finish of Polyethersulfone Membranes: Sticking PhotosensitizersâLike Marine Mussels Would Do
Biofouling is one of the most serious problems in membrane filtration systems for water treatment. An easily applicable antimicrobial finish of polyethersulfone (PES) filter membranes is shown by derivatizing an approved chlorin photosensitizer drug with adhesive ortho-catechol functionalities as known from l-3,4-dihydroxyphenylalanin (Dopa) residues of marine mussel glues. The chemical structure of the second-generation photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)chlorin (m-THPC) is modified by 2-iodoxybenzoic acid (IBX) oxidation, transforming the peripheric meta-phenols of m-THPC into ortho-catechols, and thus improving the adsorption properties of m-THPC derivatives onto PES material. Stable coatings are formed that preserve chlorin's capability to generate singlet oxygen under visible light illumination. The modification of one or two phenol groups out of the four m-THPC substituents leads to an optimum in the generation of active singlet oxygen, and thus the finish significantly reduces the bacterial growth of gram-negative Escherichia coli and gram-positive Micrococcus luteus on the PES membranes.Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659Peer Reviewe
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