1,329 research outputs found
The Real Failure Rate of Restaurants
A common assumption in the restaurant industry is that restaurants fail at an exceedingly high rate. However, statistical research to support this assumption is limited. The authors present a study of 10 years in the life of three markets and offer new data for managers to consider
Basic Skills Quality Initiative: training and development programme 2000-2003, end of project report
Minimum Free Energy, Partition Function and Kinetics Simulation Algorithms for a Multistranded Scaffolded DNA Computer
Polynomial time dynamic programming algorithms play a crucial role in the design, analysis and engineering of nucleic acid systems including DNA computers and DNA/RNA nanostructures. However, in complex multistranded or pseudoknotted systems, computing the minimum free energy (MFE), and partition function of nucleic acid systems is NP-hard. Despite this, multistranded and/or pseudoknotted systems represent some of the most utilised and successful systems in the field. This leaves open the tempting possibility that many of the kinds of multistranded and/or pseudoknotted systems we wish to engineer actually fall into restricted classes, that do in fact have polynomial time algorithms, but we\u27ve just not found them yet.
Here, we give polynomial time algorithms for MFE and partition function calculation for a restricted kind of multistranded system called the 1D scaffolded DNA computer. This model of computation thermodynamically favours correct outputs over erroneous states, simulates finite state machines in 1D and Boolean circuits in 2D, and is amenable to DNA storage applications. In an effort to begin to ask the question of whether we can naturally compare the expressivity of nucleic acid systems based on the computational complexity of prediction of their preferred energetic states, we show our MFE problem is in logspace (the complexity class L), making it perhaps one of the simplest known, natural, nucleic acid MFE problems. Finally, we provide a stochastic kinetic simulator for the 1D scaffolded DNA computer and evaluate strategies for efficiently speeding up this thermodynamically favourable system in a constant-temperature kinetic regime
Discriminative Topological Features Reveal Biological Network Mechanisms
Recent genomic and bioinformatic advances have motivated the development of
numerous random network models purporting to describe graphs of biological,
technological, and sociological origin. The success of a model has been
evaluated by how well it reproduces a few key features of the real-world data,
such as degree distributions, mean geodesic lengths, and clustering
coefficients. Often pairs of models can reproduce these features with
indistinguishable fidelity despite being generated by vastly different
mechanisms. In such cases, these few target features are insufficient to
distinguish which of the different models best describes real world networks of
interest; moreover, it is not clear a priori that any of the presently-existing
algorithms for network generation offers a predictive description of the
networks inspiring them. To derive discriminative classifiers, we construct a
mapping from the set of all graphs to a high-dimensional (in principle
infinite-dimensional) ``word space.'' This map defines an input space for
classification schemes which allow us for the first time to state unambiguously
which models are most descriptive of the networks they purport to describe. Our
training sets include networks generated from 17 models either drawn from the
literature or introduced in this work, source code for which is freely
available. We anticipate that this new approach to network analysis will be of
broad impact to a number of communities.Comment: supplemental website:
http://www.columbia.edu/itc/applied/wiggins/netclass
Using cross-talk simulation to predict the performance of anaglyph 3-D glasses
The anaglyph 3-D method is a widely used technique for presenting stereoscopic 3-D images. Its primary advantage is that it will work on any full-color display (LCDs, plasmas, and even prints) and only requires that the user view the anaglyph image using a pair of anaglyph 3-D glasses with usually one lens tinted red and the other lens tinted cyan (blue plus green). A common image-quality problem of anaglyph 3-D images is high levels of cross-talk — the incomplete isolation of the left and right image channels such that each eye sees a “ghost” of the opposite perspective view. An anaglyph cross-talk simulation model has been developed which allows the amount of anaglyph cross-talk to be estimated based on the spectral characteristics of the anaglyph glasses and the display. The model is validated using a visual cross-talk ranking test which indicates good agreement. The model is then used to consider two scenarios for the reduction of cross-talk in anaglyph systems and finds that a considerable reduction is likely to be achieved by using spectrally pure displays. The study also finds that the 3-D performance of commercial anaglyph glasses can be significantly better than handmade anaglyph glasses
Algebraic Classical and Quantum Field Theory on Causal Sets
The framework of perturbative algebraic quantum field theory (pAQFT) is used
to construct QFT models on causal sets. We discuss various discretised wave
operators, including a new proposal based on the idea of a `preferred past',
which we also introduce, and show how they may be used to construct classical
free and interacting field theory models on a fixed causal set; additionally,
we describe how the sensitivity of observables to changes in the background
causal set may be encapsulated in a relative Cauchy evolution. These structures
are used as the basis of a deformation quantization, using the methods of
pAQFT. The SJ state is defined and discussed as a particular quantum state on
the free quantum theory. Finally, using the framework of pAQFT, we construct
interacting models for arbitrary interactions that are smooth functions of the
field configurations. This is the first construction of such a wide class of
models achieved in QFT on causal sets.Comment: 42 pages, 3 figure
Using arts-based research in applied health care: An example from an evaluation of NHS dental contract reform in Wales
Aquaculture of the Big-Bellied Seahorse Hippocampus Abdominalis Lesson 1827 (Teleostei: Syngnathidae)
Seahorses (Teleostei: Syngnathidae) are subjects of worldwide demand for medicinal
use, as curios, and as live ornamental aquarium fish. Aquaculture has the potential to
replace or at least supplement potentially unsustainable wild exploitation as the supply
source of seahorses. The primary aim of the research within this thesis was to determine
techniques for improving the technical and economic feasibility for commercially
culturing the big-bellied seahorse Hippocampus abdominalis in New Zealand.
In a preliminary investigation, the breeding of wild H. abdominalis in captivity and
rearing of juveniles was examined, as difficulties have been encountered with these in
historical attempts at culturing H. abdominalis. Breeding was found to be facilitated by
providing tanks with a water height of 1 m. This depth of water allowed females to
transfer their eggs to male seahorses during the vertical rising stage of mating. Growth
rates of progeny to sexual maturity were reasonable with seahorses reaching an average
11 cm in standard length (SL) at one year of age, but high juvenile mortality was
observed in the first few months of age, with an average 10.6% of juveniles surviving to
one year. Further on-growing of these first generation progeny to seven years of age
(average of 27 cm SL for both sexes) demonstrated the robustness of the species in
captivity and potential to supply large seahorses to the medicinal trade where large size
is desirable.
To improve juvenile survival and growth, the effects of initial tank colour, lighting
arrangement and stocking density on early juveniles were tested. Juveniles at one week
of age were found to have higher attack rate and capture success on Artemia nauplii in
clear jars than those contained in white- or black-wrapped jars, but this effect of tank
colour had less affect on one month-old juveniles. Juveniles were also found to suffer
fewer incidences of air bubble ingestion in side-illuminated tanks due to positively
phototactic prey (Artemia) being drawn away from the water surface. The rearing of
juveniles from birth to two months of age in glass aquaria with side-illumination and
tank surfaces blacked-out above the waterline resulted in survival rates of >80% due to
increased feeding efficiency and reduced risk of air bubble ingestion. Juvenile growth
and survival at stocking densities of 1, 2 and 5 juveniles l-1 demonstrated that increasing
stocking density resulted in reduced growth and survival, due to the greater occurrence
of juveniles grasping and wrestling each other with their prehensile tails.
Producing live foods for fish is a significant cost in finfish culture. This has led to
concerted efforts to develop appropriate artificial or inert diets to reduce culture costs.
To determine whether juvenile seahorses could be weaned from live food to inert diets,
two inert diets (Golden Pearls and frozen copepods) were tested. It was demonstrated
that one and two month-old juvenile H. abdominalis could ingest and survive on these
inert foods. Co-feeding the inert diets with live Artemia improved feeding on the inert
foods. However, growth and survival rates of juveniles on the inert diets were inferior to
those fed only on live enriched Artemia.
Cultured live foods such as Artemia are often enriched with various enrichment media
to boost their nutritional value. However, enrichment media can vary in their nutritional
value relative to the final target organisms they are being fed to, as well as their relative
cost-effectiveness. Therefore, the effect of different Artemia enrichments on the growth
and survival of H. abdominalis and their relative cost-effectiveness was tested using
three commercial enrichment products (Super Selco®, DHA Protein Selco® and
Algamac-3050®) and a low-cost Artemia on-growing diet (EPABSF/Spirulina
platensis). On a cost/benefit basis, EPABSF/S. platensis worked out to be the most cost-
effective for H. abdominalis, with comparable growth rates to seahorses fed Artemia
enriched with DHA Protein Selco® and Algamac-3050®. Juvenile growth rates were
poorest on Artemia enriched with Super Selco®.
Feeding seahorses frozen mysid shrimp may help reduce culture costs and also increase
cultured seahorse marketability to the aquarium trade, but their efficacy in seahorse
culture is largely untested. Frozen mysids (Amblyops kempi) were shown to be an
acceptable alternative to live enriched Artemia for H. abdominalis, providing
comparable rates of seahorse growth and survival. When daily rations of frozen mysids
at 5%, 10%, 15% and 20% wet body weight (wbw) were tested there was no growth
advantage to feeding seahorses more than 5% wbw per day in terms of increase in
seahorse length. There was a wet weight gain and Condition Factor (CF) advantage
associated with increasing feed ration >10%. Feed conversion ratios (FCR) became less
efficient as feed ration increased based on the total amount of mysids offered to
seahorses, with increasing food wastage. However, when actual mysid consumption was
taken into account there were no significant differences in FCR between rations.
The natural diet and male reproductive output of H. abdominalis in Wellington Harbour
was examined for use as aquaculture benchmarks. Natural diet consisted mainly of
epibenthic and epifaunal crustaceans (e.g. amphipods, mysid shrimp and caridean
shrimp). There were no sex-related differences in diet although there were some size-
related differences with smaller seahorses consuming more amphipods. Some of the
prey species eaten by wild H. abdominalis may show potential as cultured foods. Wild
males produced an average of 271 juveniles per brood, with brood size increasing with
parent male size. Comparison of wild reproductive output data with those of cultured
male H. abdominalis revealed that cultured male output was approximately 27% lower
than that of wild males. However, there were no differences in the quality (size and
weight) of the juveniles produced by wild and cultured male H. abdominalis. It is
suggested that cultured female reproductive output is the primary determinant in lower
cultured male seahorse reproductive output.
The research within this thesis has contributed to improving the technical and economic
feasibility for commercially culturing the big-bellied seahorse Hippocampus
abdominalis
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