591 research outputs found
FliPpr: A Prettier Invertible Printing System
When implementing a programming language, we often write
a parser and a pretty-printer. However, manually writing both programs
is not only tedious but also error-prone; it may happen that a pretty-printed
result is not correctly parsed. In this paper, we propose FliPpr,
which is a program transformation system that uses program inversion
to produce a CFG parser from a pretty-printer. This novel approach
has the advantages of fine-grained control over pretty-printing, and easy
reuse of existing efficient pretty-printer and parser implementations
Ring closure reactions of bicyclic prolinol and prolin ester enantiomers
Starting from the of bicyclic proline ester, ethyl
exo-2-azabicyclo[2.2.1]heptane-3-carboxylate (+)-5 several hydantoines
and thiohydantoines were prepared by acidic ring closure of the
corresponding urea or thiourea derivatives. Enantiomer (-)-5 was
reduced to 2-azanorbornylmethanol 12, which was transformed to
5,8-methanooxazolo- and thiazolo[3,4-a] pyridine derivatives. The
structures, stereochemistry and relative configurations of the
synthesized compounds were proved by NMR
Composition of zooplankton assemblages along the Zagyva River
The species composition, longitudinal distribution and seasonal dynamics of zooplankton were
studied in the Zagyva River, Hungary. A total of 108 taxa was recorded from which 61 were new for the
river. Rotatoria was the most abundant group, microcrustaceans were less important, only nauplii and
copepodites were represented in similar individual numbers. Frequent species included Anuraeopsis fissa,
Pompholyx spp., Keratella cochlearis, Brachionus angularis, Bdelloida sp., Bosmina longirostris.
Dominance of cosmopolitan species was observed both in the river and its reservoir, and species
characteristic of eutrophic waters were of major importance in the latter. There was a downstream
decrease in zooplankton densities, which was explained by modified conditions. The relatively large
number of individuals in autumn months, and the characteristic large number of individuals in the upper
section contrasted general findings of potamoplankton dynamics. On the basis of the species abundance
matrix, three river sections can be distinguished (upper, middle, lower section). Due to waste water
discharges - received from the Tarján Stream - we found extremely high number of individuals and the
lowest diversity at the sampling site Nagybátony (148 rkm)
High precision Y(,)Y scattering at low energies
Elastic scattering cross sections of the Y(,)Y
reaction have been measured at energies E = 15.51 and 18.63 MeV. The
high precision data for the semi-magic nucleus Y are used to
derive a local potential and to evaluate the predictions of global and regional
-nucleus potentials. The variation of the elastic alpha scattering
cross sections along the isotonic chain is investigated by a study of
the ratios of angular distributions for Y(,)Y and
Mo(,)Mo at E 15.51 and 18.63
MeV. This ratio is a very sensitive probe at energies close to the Coulomb
barrier, where scattering data alone is usually not enough to characterize the
different potentials. Furthermore, -cluster states in Nb =
Y are investigated
Tracking the 10Be-26Al source-area signal in sediment-routing systems of arid central Australia
Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems ( ∼ 100 000 km2) in central Australia with the aim of tracking downstream variations in 10Be–26Al inventories and identifying the factors responsible for these variations. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55) from source areas, we show that 10Be–26Al inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream, a distinct lithological signal is retained. Post-orogenic ranges yield catchment erosion rates of ∼ 6–11 m Myr−1 and silcrete-dominant areas erode as slow as ∼ 0.2 m Myr−1. 10Be–26Al inventories in stream sediments indicate that cumulative-burial terms increase downstream to mostly ∼ 400–800 kyr and up to ∼ 1.1 Myr. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 10Be–26Al source-area signal differs according to geomorphic setting. Signal preservation is favoured by (i) high sediment supply rates, (ii) high mean runoff, and (iii) a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of (i) low sediment supply and (ii) juxtaposition of sediment storages with notably different exposure histories.Financial support was provided by an Australian Research Council grant (DP130104023) to Gerald Nanson and John D. Jansen, by a GeoQuEST Research Centre grant to John D. Jansen and Alexandru T. Codilean, a Marie Skłodowska-Curie Fellowship to John D. Jansen, and by the Centre for Accelerator Science at ANSTO through the National Collaborative Research Infrastructure Strategy. Martin Struck received an International Postgraduate Tuition Award provided by UOW and a matching scholarship funded by UOW and ANSTO
Investigation of alpha-nuclear potential families from elastic scattering experiments
In this work we present the continuation of the reported analysis [1] of the experimentally measured angular distributions of the reaction Cd-106(alpha, alpha)Cd-106 at several different energies around the Coulomb barrier. The difficulties that arise in the study of Cd-106-alpha-nuclear potential and the so called Family Problem are addressed
The 106Cd(α, α)106Cd elastic scattering in a wide energy range for γ process studies
Date of Acceptance: 15/04/2015Alpha elastic scattering angular distributions of the 106Cd(α, α)106Cd reaction were measured at three energies around the Coulomb barrier to provide a sensitive test for the α + nucleus optical potential parameter sets. Furthermore, the new high precision angular distributions, together with the data available from the literature were used to study the energy dependence of the locally optimized α + nucleus optical potential in a wide energy region ranging from ELab=27.0MeV down to 16.1 MeV.The potentials under study are a basic prerequisite for the prediction of α-induced reaction cross sections and thus, for the calculation of stellar reaction rates used for the astrophysical γ process. Therefore, statistical model predictions using as input the optical potentials discussed in the present work are compared to the available 106Cd + alpha cross section data.Peer reviewe
Quantum mechanics of a free particle on a pointed plane revisited
The detailed study of a quantum free particle on a pointed plane is
performed. It is shown that there is no problem with a mysterious ``quantum
anticentrifugal force" acting on a free particle on a plane discussed in a very
recent paper: M. A. Cirone et al, Phys. Rev. A 65, 022101 (2002), but we deal
with a purely topological efect related to distinguishing a point on a plane.
The new results are introduced concerning self-adjoint extensions of operators
describing the free particle on a pointed plane as well as the role played by
discrete symmetries in the analysis of such extensions.Comment: 4 figure
Proton induced reaction cross section measurements on Se isotopes for the astrophysical p process
As a continuation of a systematic study of reactions relevant to the
astrophysical p process, the cross sections of the 74,76Se(p,gamma)75,77Br and
82Se(p,n)82Br reactions have been measured at energies from 1.3 to 3.6 MeV
using an activation technique. The results are compared to the predictions of
Hauser-Feshbach statistical model calculations using the NON-SMOKER and MOST
codes. The sensitivity of the calculations to variations in the optical proton
potential and the nuclear level density was studied. Good agreement between
theoretical and experimental reaction rates was found for the reactions
74Se(p,gamma)75Br and 82Se(p,n)82Br.Comment: 9 pages, 6 figures (in 12 eps files), accepted for publication in
Phys. Rev C, RevTeX styl
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