188 research outputs found
Scottish input-output tables for 1979
Scotland, for the year 1973, were published in 1978, as a result of a collaborative effort between the Fraser of Allander Institute, the IBM Scientific Centre and the Scottish Council Research Institute. A second set of tables, for the year 1979, have been compiled by the Industry Department for Scotland (IDS) and the results have recently been published in a series of four special volumes. The compilation of input-output tables is a complex exercise which involves a substantial commitment of resources and time, which explains the long interval (nearly five years) between the base year of the tables and the publication of the results. The tables however reveal a great deal about the structure of the economy and have a wide range of applications. The next section of this paper explains what input-output tables are, while the following section summarises the main features of the Scottish tables for 1979. The last part of the paper outlines some applications of input-output models, and gives some examples of applications in the Scottish context
Independent Orbiter Assessment (IOA): Analysis of the orbiter main propulsion system
The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Main Propulsion System (MPS) hardware are documented. The Orbiter MPS consists of two subsystems: the Propellant Management Subsystem (PMS) and the Helium Subsystem. The PMS is a system of manifolds, distribution lines and valves by which the liquid propellants pass from the External Tank (ET) to the Space Shuttle Main Engines (SSMEs) and gaseous propellants pass from the SSMEs to the ET. The Helium Subsystem consists of a series of helium supply tanks and their associated regulators, check valves, distribution lines, and control valves. The Helium Subsystem supplies helium that is used within the SSMEs for inflight purges and provides pressure for actuation of SSME valves during emergency pneumatic shutdowns. The balance of the helium is used to provide pressure to operate the pneumatically actuated valves within the PMS. Each component was evaluated and analyzed for possible failure modes and effects. Criticalities were assigned based on the worst possible effect of each failure mode. Of the 690 failure modes analyzed, 349 were determined to be PCIs
Long and repeat-rich intronic sequences favor circular RNA formation under conditions of reduced spliceosome activity
Circular RNAs (circRNAs), an important class of regulatory RNAs, have been shown to be the most prevalent in the brain compared with other tissues. However the processes governing their biogenesis in neurons are still elusive. Moreover, little is known about whether and how different biogenesis factors work in synchrony to generate neuronal circRNAs. To address this question, we pharmacologically inhibited the spliceosome and profiled rat neuronal circRNAs using RNA sequencing. We identified over 100 circRNAs that were up-regulated and a few circRNAs that were down-regulated upon spliceosome inhibition. Bioinformatic analysis revealed that up-regulated circRNAs possess significantly longer flanking introns compared with the un-changed circRNA population. Moreover, the flanking introns of up-regulated circRNAs harbor a higher number of distinct repeat sequences and more reverse complementary motifs compared with the unchanged circRNAs. Taken together, our data demonstrate that the biogenesis of circRNAs containing distinct intronic features becomes favored under conditions of limited spliceosome activity
Measurement of the transverse target and beam-target asymmetries in meson photoproduction at MAMI
We present new data for the transverse target asymmetry T and the very first
data for the beam-target asymmetry F in the
reaction up to a center-of-mass energy of W=1.9 GeV. The data were obtained
with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility
of the Mainz Microtron MAMI. All existing model predictions fail to reproduce
the new data indicating a significant impact on our understanding of the
underlying dynamics of meson photoproduction. The peculiar nodal
structure observed in existing T data close to threshold is not confirmed.Comment: 5 pages, 3 figures, accepted for publication in PR
T and F asymmetries in π0 photoproduction on the proton
The γp→π0p reaction was studied at laboratory photon energies from 425 to 1445 MeV with a transversely polarized target and a longitudinally polarized beam. The beam-target asymmetry F was measured for the first time and new high precision data for the target asymmetry T were obtained. The experiment was performed at the photon tagging facility of the Mainz Microtron (MAMI) using the Crystal Ball and TAPS photon spectrometers. The polarized cross sections were expanded in terms of associated Legendre functions and compared to recent predictions from several partial-wave analyses. The impact of the new data on our understanding of the underlying partial-wave amplitudes and baryon resonance contributions is discussed
Quasi-free photoproduction of η-mesons off 3He nuclei
Quasi-free photoproduction of η-mesons has been measured off nucleons bound in 3He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with an almost 4π covering electromagnetic calorimeter, combining the TAPS and Crystal Ball detectors. The η-mesons were detected in coincidence with the recoil nucleons. This allowed a comparison of the production cross section off quasi-free protons and quasi-free neutrons and a full kinematic reconstruction of the final state, eliminating effects from nuclear Fermi motion. In the S11(1535) resonance peak, the data agree with the neutron/proton cross section ratio extracted from measurements with deuteron targets. More importantly, the prominent structure observed in photoproduction off quasi-free neutrons bound in the deuteron is also clearly observed. Its parameters (width, strength) are consistent with the expectations from the deuteron results. On an absolute scale the cross sections for both quasi-free protons and neutrons are suppressed with respect to the deuteron target pointing to significant nuclear final-state interaction effects
Photoproduction of -pairs off protons and off neutrons
Total cross sections, angular distributions, and invariant-mass distributions
have been measured for the photoproduction of pairs off free
protons and off nucleons bound in the deuteron. The experiments were performed
at the MAMI accelerator facility in Mainz using the Glasgow photon tagging
spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered
electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin
radiator foils. The tagged photon beam covered energies up to 1400~MeV. The
data from the free proton target are in good agreement with previous
measurements and were only used to test the analysis procedures. The results
for differential cross sections (angular distributions and invariant-mass
distributions) for free and quasi-free protons are almost identical in shape,
but differ in absolute magnitude up to 15\%. Thus, moderate final-state
interaction effects are present. The data for quasi-free neutrons are similar
to the proton data in the second resonance region (final state invariant masses
up to 1550~MeV), where both reactions are dominated by the
decay. At higher energies,
angular and invariant-mass distributions are different. A simple analysis of
the shapes of the invariant-mass distributions in the third resonance region is
consistent with strong contributions of an decay
for the proton, while the reaction is dominated by a sequential decay via a
intermediate state for the neutron. The data are compared to
predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled channel
analysis.Comment: accepted for publication in Eur. Phys. J.
Measurement of the beam-helicity asymmetry in the photoproduction of -pairs off protons and off neutrons
Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz
for the photoproduction of mixed-charge pion pairs in the reactions
off free protons and
and
off quasi-free nucleons bound
in the deuteron for incident photon energies up to 1.4 GeV. Circularly
polarized photons were produced from bremsstrahlung of longitudinally polarized
electrons and tagged with the Glasgow-Mainz magnetic spectrometer. The charged
pions, recoil protons, recoil neutrons, and decay photons from mesons
were detected in the 4 electromagnetic calorimeter composed of the Crystal
Ball and TAPS detectors. Using a complete kinematic reconstruction of the final
state, excellent agreement was found between the results for free and
quasi-free protons, suggesting that the quasi-free neutron results are also a
close approximation of the free-neutron asymmetries. A comparison of the
results to the predictions of the Two-Pion-MAID reaction model shows that the
reaction mechanisms are still not well understood, in particular at low
incident photon energies in the second nucleon-resonance region.Comment: accepted for publication in Eur. phys. J.
Photoproduction of pi0-mesons off neutrons in the nucleon resonance region
Precise angular distributions have been measured for the first time for the
photoproduction of -mesons off neutrons bound in the deuteron. The
effects from nuclear Fermi motion have been eliminated by a complete kinematic
reconstruction of the final state. The influence of final-state-interaction
effects has been estimated by a comparison of the reaction cross section for
quasi-free protons bound in the deuteron to the results for free protons and
then applied as a correction to the quasi-free neutron data. The experiment was
performed at the tagged photon facility of the Mainz Microtron MAMI with the
Crystal Ball and TAPS detector setup for incident photon energies between
~GeV and ~GeV. The results are compared to the predictions from
reaction models and partial-wave analyses based on data from other isospin
channels. The model predictions show large discrepancies among each other and
the present data will provide much tighter constraints. This is demonstrated by
the results of a new analysis in the framework of the Bonn-Gatchina
coupled-channel analysis which included the present data.Comment: accepted for publication in Phys; Rev. Let
The isospin structure of photoproduction of pi-eta pairs from the nucleon in the threshold region
Photoproduction of -pairs from nucleons has been investigated from
threshold up to incident photon energies of ~1.4~GeV. The quasi-free
reactions , ,
, and were for
the first time measured from nucleons bound in the deuteron. The corresponding
reactions from a free-proton target were also studied to investigate
final-state interaction effects (for neutral pions the free-proton results
could be compared to previous measurements; the reaction was measured for the first time). For the
final state coherent production via the
reaction was also investigated. The experiments were performed at the tagged
photon beam of the Mainz MAMI accelerator using an almost coverage
electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors.
The total cross sections for the four different final states obey the relation
as expected for a
dominant contribution from a
reaction chain,
which is also supported by the shapes of the invariant-mass distributions of
nucleon-meson and - pairs. The experimental results are compared to
the predictions from an isobar reaction model.Comment: accepted for publication in Phys. Lett.
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