316 research outputs found
Experiments in the automatic marking of ER-Diagrams
In this paper we present an approach to the computer understanding of diagrams and show how it can be successfully applied to the automatic marking (grading) of student attempts at drawing entity-relationship (ER) diagrams. The automatic marker has been incorporated into a revision tool to enable students to practice diagramming and obtain feedback on their attempts
Using patterns in the automatic marking of ER-Diagrams
This paper illustrates how the notion of pattern can be used in the automatic analysis and synthesis of diagrams, applied particularly to the automatic marking of ER-diagrams. The paper describes how diagram patterns fit into a general framework for diagram interpretation and provides examples of how patterns can be exploited in other fields. Diagram patterns are defined and specified within the area of ER-diagrams. The paper also shows how patterns are being exploited in a revision tool for understanding ER-diagrams
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Performance of antisapstain compounds on kiln-dried Douglas-fir and hem-fir lumber subjected to rewetting
Mold and stain fungi can be easily controlled by kiln-drying, but even this material can be rewetted during shipping and storage, allowing fungi to colonize the wood. The potential for using surface spray treatments with commercial formulations containing combinations of propiconazole, didecyldimethyl ammonium chloride, or 3-iodo-2-propynyl butylcarbamate to protect kiln-dried Douglas-fir and hem-fir lumber was evaluated over an 18-month storage period. Rewetted, untreated wood was readily colonized by fungi, while the treated boards experienced much lower levels of discoloration. Protection did appear to decline with storage time for hem-fir but not Douglas-fir. Chemical treatment of kiln-dried lumber may provide added protection against rewetting during transit and prior to installation in dry applications
Preheating After Modular Inflation
We study (p)reheating in modular (closed string) inflationary scenarios, with
a special emphasis on Kahler moduli/Roulette models. It is usually assumed that
reheating in such models occurs through perturbative decays. However, we find
that there are very strong non-perturbative preheating decay channels related
to the particular shape of the inflaton potential (which is highly nonlinear
and has a very steep minimum). Preheating after modular inflation, proceeding
through a combination of tachyonic instability and broad-band parametric
resonance, is perhaps the most violent example of preheating after inflation
known in the literature. Further, we consider the subsequent transfer of energy
to the standard model sector in scenarios where the standard model particles
are confined to a D7-brane wrapping the inflationary blow-up cycle of the
compactification manifold or, more interestingly, a non-inflationary blow up
cycle. We explicitly identify the decay channels of the inflaton in these two
scenarios. We also consider the case where the inflationary cycle shrinks to
the string scale at the end of inflation; here a field theoretical treatment of
reheating is insufficient and one must turn instead to a stringy description.
We estimate the decay rate of the inflaton and the reheat temperature for
various scenarios.Comment: 34 pages, 10 figures. Accepted for publication in JCA
Reheating the Universe After Multi-Field Inflation
We study in detail (p)reheating after multi-field inflation models with a
particular focus on N-flation. We consider a variety of different couplings
between the inflatons and the matter sector, including both quartic and
trilinear interactions with a light scalar field. We show that the presence of
multiple oscillating inflatons makes parametric resonance inefficient in the
case of the quartic interactions. Moreover, perturbative processes do not
permit a complete decay of the inflaton for this coupling. In order to recover
the hot big bang, we must instead consider trilinear couplings. In this case we
show that strong nonperturbative preheating is possible via multi-field
tachyonic resonance. In addition, late-time perturbative effects do permit a
complete decay of the condensate. We also study the production of gauge fields
for several prototype couplings, finding similar results to the trilinear
scalar coupling. During the course of our analysis we develop the mathematical
theory of the quasi-periodic Mathieu equation, the multi-field generalization
of the Floquet theory familiar from preheating after single field inflation. We
also elaborate on the theory of perturbative decays of a classical inflaton
condensate, which is applicable in single-field models also.Comment: 46+1 pages, 19 figure
Block copolypeptide nanoparticles for the delivery of ocular therapeutics
Self-assembling block copolypeptides were prepared by sequential ring-opening polymerization of N-carboxyanhydride (NCA) derivatives of γ-benzyl-L-glutamic acid and ε-carbobenzyloxy-L-lysine, followed by selective deprotection of the benzyl glutamate block. The synthesized polymers had number average molecular weights close to theoretical values, and had low dispersities (ĐM = 1.15–1.28). Self-assembly of the amphiphilic block copolymers into nanoparticles was achieved using the “solvent-switch” method, whereby the polymer was dissolved in THF and water and the organic solvent removed by rotary evaporation. The type of nanostructures formed varied from spherical micelles to a mixture of spherical and worm-like micelles, depending on copolymer composition. The spherical micelles had an average diameter of 43 nm by dynamic light scattering, while the apparent diameter of the mixed phase system was around 200nm. Reproducibility of nanoparticle preparation was demonstrated to be excellent; almost identical DLS traces were obtained over three repeats. Following qualitative dye-solubilization experiments, the nanoparticles were loaded with the ocular anti-inflammatory drug dexamethasone. Loading efficiency of the nanoparticles was 90% and the cumulative drug release was 94% over 16 d, with a 20% burst release in the first 24 h.mabi201400471-gra-000
Phenomenology of a Pseudo-Scalar Inflaton: Naturally Large Nongaussianity
Many controlled realizations of chaotic inflation employ pseudo-scalar
axions. Pseudo-scalars \phi are naturally coupled to gauge fields through c
\phi F \tilde{F}. In the presence of this coupling, gauge field quanta are
copiously produced by the rolling inflaton. The produced gauge quanta, in turn,
source inflaton fluctuations via inverse decay. These new cosmological
perturbations add incoherently with the "vacuum" perturbations, and are highly
nongaussian. This provides a natural mechanism to generate large nongaussianity
in single or multi field slow-roll inflation. The resulting phenomenological
signatures are highly distinctive: large nongaussianity of (nearly) equilateral
shape, in addition to detectably large values of both the scalar spectral tilt
and tensor-to-scalar ratio (both being typical of large field inflation). The
WMAP bound on nongaussianity implies that the coupling, c, of the pseudo-scalar
inflaton to any gauge field must be smaller than about 10^{2} M_p^{-1}.Comment: 45 pages, 7 figure
Automated link analysis using radio frequency identification (RFID)
Being able to accurately record the interactions which take place within any
environment is beneficial for understanding human behaviour in a wide range of
industries. Link Analysis is a standard technique which is often used, but
traditional pen and paper methods are cumbersome and time consuming. This
paper details a way to automate recording the interactions between a human and
their current environment by using radio frequency identification (RFID) tags and
a subject-mounted receiver. Using the results from the system, it is possible to
instantly create conventional Link Analysis diagrams and tables, reducing the time
and resources required for data collection and analysis. The system has been
developed in partnership with the Healthcare Ergonomics and Patient Safety Unit
(HEPSU) at Loughborough University, with initial focus being on monitoring
paramedics, patients and environment interactions within an ambulance; however,
the technologies and the analyser system are not limited to use within this
particular field
Zero-divisor graphs of nilpotent-free semigroups
We find strong relationships between the zero-divisor graphs of apparently
disparate kinds of nilpotent-free semigroups by introducing the notion of an
\emph{Armendariz map} between such semigroups, which preserves many
graph-theoretic invariants. We use it to give relationships between the
zero-divisor graph of a ring, a polynomial ring, and the annihilating-ideal
graph. Then we give relationships between the zero-divisor graphs of certain
topological spaces (so-called pearled spaces), prime spectra, maximal spectra,
tensor-product semigroups, and the semigroup of ideals under addition,
obtaining surprisingly strong structure theorems relating ring-theoretic and
topological properties to graph-theoretic invariants of the corresponding
graphs.Comment: Expanded first paragraph in section 6. To appear in J. Algebraic
Combin. 22 page
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
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