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Mylar and polypropylene laminates with aluminum as materials for communication satellite

Sequential and ordered assembly of E1 initiator complexes on the papillomavirus origin of DNA replication generates progressive structural changes related to melting

Multiple binding sites for an initiator protein are a common feature of replicator sequences from various organisms. By binding to the replicator, initiators mark the site and contribute to melting or distortion of the DNA by largely unknown mechanisms. Here we analyze origin of DNA replication (ori) binding by the E1 initiator and show sequential binding to a set of overlapping binding sites. The assembly of these initiator complexes is controlled by a gradual reduction in the dependence of interactions between the initiator and DNA and a gradual increase in the reliance on interactions between initiator molecules, providing a mechanism for sequential and orderly assembly. Importantly, the binding of the initiator causes progressive structural alterations both in the sites and in the sequences flanking the sites, eventually generating severe structural alterations. These results indicate that the process of template melting may be incremental, where binding of each initiator molecule serves as a wedge that upon binding gradually alters the template structure. This mechanism may explain the requirement for multiple initiator binding sites that is observed in many ori's

Specific recognition nucleotides and their DNA context determine the affinity of E2 protein for 17 binding sites in the BPV-1 genome

The DNA context of nucleotides that a protein recognizes can influence the strength of the protein-DNA interaction. Moreover, in prokaryotes, understanding the quantitative differences in binding affinities that result in part from the DNA context is often important in describing regulatory mechanisms. Nevertheless, these issues have not been a major focus yet for the investigation of protein-DNA interactions in eukaryotes. In this study, we explored the binding specificity and the range of affinities that the BPV-1 E2 transcriptional activator has for DNA. Because E2 binding sites are positioned near several different BPV-1 promoters, such quantitative information may be important to understand transcriptional regulatory mechanisms in BPV-1. Gel retardation assays and DNA footprinting were used to quantitate the affinities of the E2 binding sites in the viral genome. In the process, five sites were discovered, which, on the basis of sequence, had not been predicted previously to interact with the E2 protein. Equilibrium and kinetic studies show that the range of E2 affinities of the 17 sites varied over 300-fold. The sequence elements responsible for E2 recognition of DNA were determined by missing contact analysis of several sites and a point mutation analysis of one site. The results presented show that the affinity of an E2 binding site is to a large extent determined by the availability of specific contacts, but the data also strongly suggest that DNA structure plays an important role

Neutral Pion Distributions in PHENIX at RHIC

Transverse momentum spectra for identified $\pi^0$'s in the range 1 GeV/c $< p_T <$ 4 GeV/c have been measured by the PHENIX experiment in Au-Au collisions at $\sqrt{s}=130$ GeV. The spectra from peripheral nuclear collisions are consistent with the simple expectation of scaling the spectra from p+p collisions by the average number of nucleon-nucleon binary collisions. The spectra from central collisions and the ratio of central/peripheral spectra are significantly suppressed when compared to point-like scaling.Comment: 6 pages, 3 figure

Deterministic Walks in Quenched Random Environments of Chaotic Maps

This paper concerns the propagation of particles through a quenched random medium. In the one- and two-dimensional models considered, the local dynamics is given by expanding circle maps and hyperbolic toral automorphisms, respectively. The particle motion in both models is chaotic and found to fluctuate about a linear drift. In the proper scaling limit, the cumulative distribution function of the fluctuations converges to a Gaussian one with system dependent variance while the density function shows no convergence to any function. We have verified our analytical results using extreme precision numerical computations.Comment: 18 pages, 9 figure

Peculiarities in produced particles emission in 208Pb + Ag(Br) interactions at 158 A GeV/c

The angular structures of particles produced in 208Pb induced collisions with Ag(Br) nuclei in an emulsion detector at 158 A GeV/c have been investigated. Nonstatistical ring-like substructures in azimuthal plane of the collision have been found and their parameters have been determined. The indication on the formation of the ring-like substructures from two symmetrical emission cones - one in the forward and other in the backward direction in the center-of mass system have been obtained. The ring-like substructures parameters have been determined. The experimental results are in an agreement with I.M. Dremin idea, that mechanism of the ring-like substructures formation in nuclear collisions is similar to that of Cherenkov electromagnetic radiation.Comment: 10 pages, 7 figures, Report at the HADRON STRUCTURE'04 Conference, Smolenice, Slovakia, 30.8.-3.9.200

Azimuthal Correlations in the Target Fragmentation Region of High Energy Nuclear Collisions

Results on the target mass dependence of proton and pion pseudorapidity distributions and of their azimuthal correlations in the target rapidity range $-1.73 \le \eta \le 1.32$ are presented. The data have been taken with the Plastic-Ball detector set-up for 4.9 GeV p + Au collisions at the Berkeley BEVALAC and for 200 $A\cdot$GeV/$c$ p-, O-, and S-induced reactions on different nuclei at the CERN-SPS. The yield of protons at backward rapidities is found to be proportional to the target mass. Although protons show a typical ``back-to-back'' correlations, a ``side-by-side'' correlation is observed for positive pions, which increases both with target mass and with impact parameter of a collision. The data can consistently be described by assuming strong rescattering phenomena including pion absorption effects in the entire excited target nucleus.Comment: 7 pages, figures included, complete postscript available at ftp://qgp.uni-muenster.de/pub/paper/azi-correlations.ps submitted to Phys. Lett.

DGAT1 activity synchronises with mitophagy to protect cells from metabolic rewiring by iron depletion

Mitophagy removes defective mitochondria via lysosomal elimination. Increased mitophagy coincides with metabolic reprogramming, yet it remains unknown whether mitophagy is a cause or consequence of such state changes. The signalling pathways that integrate with mitophagy to sustain cell and tissue integrity also remain poorly defined. We performed temporal metabolomics on mammalian cells treated with deferiprone, a therapeutic iron chelator that stimulates PINK1/PARKIN-independent mitophagy. Iron depletion profoundly rewired the metabolome, hallmarked by remodelling of lipid metabolism within minutes of treatment. DGAT1-dependent lipid droplet biosynthesis occurred several hours before mitochondrial clearance, with lipid droplets bordering mitochondria upon iron chelation. We demonstrate that DGAT1 inhibition restricts mitophagy in vitro, with impaired lysosomal homeostasis and cell viability. Importantly, genetic depletion of DGAT1 in vivo significantly impaired neuronal mitophagy and locomotor function in Drosophila. Our data define iron depletion as a potent signal that rapidly reshapes metabolism and establishes an unexpected synergy between lipid homeostasis and mitophagy that safeguards cell and tissue integrity.Peer reviewe

Charged particle production in the Pb+Pb system at 158 GeV/c per nucleon

Charged particle multiplicities from high multiplicity central interactions of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured in the central and far forward projectile spectator regions using emulsion chambers. Multiplicities are significantly lower than predicted by Monte Carlo simulations. We examine the shape of the pseudorapidity distribution and its dependence on centrality in detail.Comment: 17 pages text plus 12 figures in postscript 12/23/99 -- Add TeX version of sourc