A Database for Fast Access to Particle-Gated Event Data

In nuclear physics experiments involving in-flight fragmentation of ions, usually a large number of different nuclei is produced and various detection systems are employed to identify the species event by event, e.g. by measuring their specific energy loss and time-of-flight. For such cases -- not necessarily limited to nuclear physics -- where subsets of a large dataset can be identified using a small number of measured signals a software for fast access to varying subsets of such a dataset has been developed. The software has been used successfully in the analysis of a one neutron knock-out experiment at GANIL

The SiRi Particle-Telescope System

A silicon particle-telescope system for light-ion nuclear reactions is described. In particular, the system is designed to be optimized for level density and gamma-ray strength function measurements with the so-called Oslo method. Eight trapezoidal modules are mounted at 5 cm distance from the target, covering 8 forward angles between theta = 40 and 54 degrees. The thin front dE detectors (130 micrometer) are segmented into eight pads, determining the reaction angle for the outgoing charged ejectile. Guard rings on the thick back E detectors (1550 micrometer) guarantee low leakage current at high depletion voltage.Comment: 6 pages, 8 figure

Phenotypic Mutation Rates and the Abundance of Abnormal Proteins in Yeast

Phenotypic mutations are errors that occur during protein synthesis. These errors lead to amino acid substitutions that give rise to abnormal proteins. Experiments suggest that such errors are quite common. We present a model to study the effect of phenotypic mutation rates on the amount of abnormal proteins in a cell. In our model, genes are regulated to synthesize a certain number of functional proteins. During this process, depending on the phenotypic mutation rate, abnormal proteins are generated. We use data on protein length and abundance in Saccharomyces cerevisiae to parametrize our model. We calculate that for small phenotypic mutation rates most abnormal proteins originate from highly expressed genes that are on average nearly twice as large as the average yeast protein. For phenotypic mutation rates much above 5 × 10−4, the error-free synthesis of large proteins is nearly impossible and lowly expressed, very large proteins contribute more and more to the amount of abnormal proteins in a cell. This fact leads to a steep increase of the amount of abnormal proteins for phenotypic mutation rates above 5 × 10−4. Simulations show that this property leads to an upper limit for the phenotypic mutation rate of approximately 2 × 10−3 even if the costs for abnormal proteins are extremely low. We also consider the adaptation of individual proteins. Individual genes/proteins can decrease their phenotypic mutation rate by using preferred codons or by increasing their robustness against amino acid substitutions. We discuss the similarities and differences between the two mechanisms and show that they can only slow down but not prevent the rapid increase of the amount of abnormal proteins. Our work allows us to estimate the phenotypic mutation rate based on data on the fraction of abnormal proteins. For S. cerevisiae, we predict that the value for the phenotypic mutation rate is between 2 × 10−4 and 6 × 10−4

Fully adaptive multiresolution schemes for strongly degenerate parabolic equations with discontinuous flux

A fully adaptive finite volume multiresolution scheme for one-dimensional strongly degenerate parabolic equations with discontinuous flux is presented. The numerical scheme is based on a finite volume discretization using the Engquist--Osher approximation for the flux and explicit time--stepping. An adaptivemultiresolution scheme with cell averages is then used to speed up CPU time and meet memory requirements. A particular feature of our scheme is the storage of the multiresolution representation of the solution in a dynamic graded tree, for the sake of data compression and to facilitate navigation. Applications to traffic flow with driver reaction and a clarifier--thickener model illustrate the efficiency of this method

Originator Dynamics

We study the origin of evolution. Evolution is based on replication, mutation, and selection. But how does evolution begin? When do chemical kinetics turn into evolutionary dynamics? We propose “prelife” and “prevolution” as the logical precursors of life and evolution. Prelife generates sequences of variable length. Prelife is a generative chemistry that proliferates information and produces diversity without replication. The resulting “prevolutionary dynamics” have mutation and selection. We propose an equation that allows us to investigate the origin of evolution. In one limit, this “originator equation” gives the classical selection equation. In the other limit, we obtain “prelife.” There is competition between life and prelife and there can be selection for or against replication. Simple prelife equations with uniform rate constants have the property that longer sequences are exponentially less frequent than shorter ones. But replication can reverse such an ordering. As the replication rate increases, some longer sequences can become more frequent than shorter ones. Thus, replication can lead to “reversals” in the equilibrium portraits. We study these reversals, which mark the transition from prelife to life in our model. If the replication potential exceeds a critical value, then life replicates into existence.MathematicsOrganismic and Evolutionary Biolog

Observation of large scissors resonance strength in actinides

The orbital M1-scissors resonance (SR) has been measured for the first time in the quasi-continuum of actinides. Particle-gamma coincidences are recorded with deuteron and 3He induced reactions on 232Th. The residual nuclei 231,232,233Th and 232,233Pa show an unexpectedly strong integrated strength of $B_{M1} = 11-15 \mu_{n}^{2}$ in the Egamma=1.0 - 3.5 MeV region. The increased gamma-decay probability in actinides due to the SR is important for cross-section calculations for future fuel cycles of fast nuclear reactors and may also have impact on stellar nucleosynthesis.Comment: 5 pages and 4 figure

Dynamics of Competitive Evolution on a Smooth Landscape

We study competitive DNA sequence evolution directed by {\it in vitro} protein binding. The steady-state dynamics of this process is well described by a shape-preserving pulse which decelerates and eventually reaches equilibrium. We explain this dynamical behavior within a continuum mean-field framework. Analytical results obtained on the motion of the pulse agree with simulations. Furthermore, finite population correction to the mean-field results are found to be insignificant.Comment: 4 pages, 2 figures, revised, to appear in Phys. Rev. Let

Extraction of thermal and electromagnetic properties in 45Ti

The level density and gamma-ray strength function of 45Ti have been determined by use of the Oslo method. The particle-gamma coincidences from the 46Ti(p,d gamma)45Ti pick-up reaction with 32 MeV protons are utilized to obtain gamma-ray spectra as function of excitation energy. The extracted level density and strength function are compared with models, which are found to describe these quantities satisfactorily. The data do not reveal any single-particle energy gaps of the underlying doubly magic 40Ca core, probably due to the strong quadruple deformation

Production of an Anise-and Woodruff-like Aroma by Monokaryotic Strains of Pleurotus sapidus Grown on Citrus Side Streams

The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic-and woodruff-like) with a flavor dilution factor of 218 as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L−1 to 2.4 ng L−1 for the first time. Supplementation of the culture medium with isotopically substituted L-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus