106 research outputs found
An Optimal Surveillance Measure Against Foot-and-Mouth Disease in the United States
Surveillance programs on farms and in the local environment provide an essential protection against the importation and spread of exotic diseases. Combined with border quarantine measures, these programs protect both consumers and producers from major health concerns and disease incursions that can potentially destroy local agricultural production and supporting industries, as well as generate substantial losses in trade and tourism. However, surveillance programs also impose costs in the form of expenditures on the surveillance program itself, along with the costs of disease management and eradication should an incursion occur. Taking border quarantine expenditures as given, this paper develops a stochastic optimal control model (with a jump-diffusion process) to determine the optimal level of surveillance activity against a disease incursion by minimizing the present value of the major direct and indirect costs of the disease, as well as the cost of the surveillance and disease management and eradication programs. The model is applied to the case of a potential entry and spread of Foot-and-Mouth Disease in the United States. Results show that current surveillance expenditures are far less than optimal.Surveillance measures, border quarantine, disease incursion and spread, Foot- and-Mouth disease, stochastic optimal control, Livestock Production/Industries, Q1, Q17, Q18,
The Effects of Climate Change on GDP by Country and the Global Economic Gains From Complying With the Paris Climate Accord
Computable general equilibrium (CGE) models are a standard tool for policy analysis and
forecasts of economic growth. Unfortunately, due to computational constraints, many CGE models
are dimensionally small, aggregating countries into an often limited set of regions or using assumptions
such as static price-level expectations, where next periodâs price is conditional only on current or past prices.
This is a concern for climate change modeling, since the effects of global warming by country, in a fully
disaggregated and global trade model, are needed, and the known future effects of global warming should
be included in forward-looking forecasts for prices and profitability. This work extends a large dimensional
intertemporal CGE trade model to account for the various effects of global warming (e.g., loss in agricultural
productivity, sea level rise, and health effects) on Gross Domestic Product (GDP) growth and levels for
139 countries, by decade and over the long term, where producers look forward and adjust price
expectations and capital stocks to account for future climate effects. The potential economic gains from
complying with the Paris Accord are also estimated, showing that even with a limited set of possible
damages from global warming, these gains are substantial. For example, with the comparative case
of Representative Concentration Pathway 8.5 (4âC), the global gains from complying with the 2âC target
(Representative Concentration Pathway 4.5) are approximately US$17,489 billion per year in the long
run (year 2100). The relative damages from not complying to Sub-Sahara Africa, India, and Southeast Asia,
across all temperature ranges, are especially severe
A Multiple Choices Reading Comprehension Corpus for Vietnamese Language Education
Machine reading comprehension has been an interesting and challenging task in
recent years, with the purpose of extracting useful information from texts. To
attain the computer ability to understand the reading text and answer relevant
information, we introduce ViMMRC 2.0 - an extension of the previous ViMMRC for
the task of multiple-choice reading comprehension in Vietnamese Textbooks which
contain the reading articles for students from Grade 1 to Grade 12. This
dataset has 699 reading passages which are prose and poems, and 5,273
questions. The questions in the new dataset are not fixed with four options as
in the previous version. Moreover, the difficulty of questions is increased,
which challenges the models to find the correct choice. The computer must
understand the whole context of the reading passage, the question, and the
content of each choice to extract the right answers. Hence, we propose the
multi-stage approach that combines the multi-step attention network (MAN) with
the natural language inference (NLI) task to enhance the performance of the
reading comprehension model. Then, we compare the proposed methodology with the
baseline BERTology models on the new dataset and the ViMMRC 1.0. Our
multi-stage models achieved 58.81% by Accuracy on the test set, which is 5.34%
better than the highest BERTology models. From the results of the error
analysis, we found the challenge of the reading comprehension models is
understanding the implicit context in texts and linking them together in order
to find the correct answers. Finally, we hope our new dataset will motivate
further research in enhancing the language understanding ability of computers
in the Vietnamese language
Boundary layers and emitted excitations in nonlinear Schrodinger superflow past a disk
The stability and dynamics of nonlinear Schrodinger superflows past a
two-dimensional disk are investigated using a specially adapted pseudo-spectral
method based on mapped Chebychev polynomials. This efficient numerical method
allows the imposition of both Dirichlet and Neumann boundary conditions at the
disk border. Small coherence length boundary-layer approximations to stationary
solutions are obtained analytically. Newton branch-following is used to compute
the complete bifurcation diagram of stationary solutions. The dependence of the
critical Mach number on the coherence length is characterized. Above the
critical Mach number, at coherence length larger than fifteen times the
diameter of the disk, rarefaction pulses are dynamically nucleated, replacing
the vortices that are nucleated at small coherence length
Least Expected Time Paths in Stochastic Schedule-Based Transit Networks
We consider the problem of determining a least expected time (LET) path that minimizes the number of transfers and the expected total travel time in a stochastic schedule-based transit network. A time-dependent model is proposed to represent the stochastic transit network where vehicle arrival times are fully stochastically correlated. An exact label-correcting algorithm is developed, based on a proposed dominance condition by which Bellmanâs principle of optimality is valid. Experimental results, which are conducted on the Ho Chi Minh City bus network, show that the running time of the proposed algorithm is suitable for real-time operation, and the resulting LET paths are robust against uncertainty, such as unknown traffic scenarios
Teaching practicum: The impacts on classroom management skills of novice lecturers
This research investigates the perspectives of the novice lecturers in the Faculty of English Language Teacher Education (FELTE) regarding Teaching Practicumâs impacts on their classroom management skills. Using survey research, data was gathered through questionnaires distributed among the whole population of 29 participants, followed by semi-structured interviews to gain a deeper insight into participantsâ experience. The studyâs results showed that novice lecturers generally made considerable progress in classroom management skills, especially in attention-drawing and response encouragement, creation of a motivating environment as well as physical and emotional interactions with students. On the other hand, it was discovered that inadequate duration and inappropriate timing generally impeded novice lecturersâ gains during their Teaching Practicum. However, some challenges related to supervisor and school choice turned out to be significant factors from which participants could derive considerable benefits, which is opposed to previous research. At the end of the study, some recommendations were suggested for future research on this topic
Characterization and utilization of pulp and paper mill sludge digesting thermophilic bacteria in composting process
Pulp and paper mill sludge (PPMS) was found to be poorly colonised with thermophilic microorganisms. However, evidence to support the need for inoculation to facilitate PPMS composting has only been demonstrated in one instance. In this study, we aimed to: screen and identify PPMS digesting thermophilic bacterial strains; investigate effects of the mixture of selected thermophilic bacterial strains on PPMS digestion; and utilize this mixture as start inoculum in PPMS composting and assess the quality of compost product. The results showed that eleven thermophilic bacterial strains were isolated from Bai Bang PPMS by the enrichment culture method. Among these, three strains which reflected high growth rates on the plates of Minimal Media Agar supplemented with Bai Bang PPMS and showed hydrolytic and ligninolytic activities on the agar plates containing appropriate inductive substrates were selected. Based on the morphological, biochemical characteristics and 16S rRNA gene sequencing, they were identified as Bacillus subtilis. The inoculation with the mixture of selected strains enhanced remarkably Bai Bang PPMS digestion. The dry weight decrease, volatile suspended solids removal, dehydrogenase and protease activities in the inoculated sludge were 2.1-, 1.5-, 1.3- and 1.2- fold higher, respectively, compared to the non-inoculated sludge. The assessment of compost quality based on stability using the alkaline trap method and maturity using the germination and root elongation test showed that the inoculated compost was stable and mature while the non-inoculated compost was unstable and immature. These thermophilic bacterial strains therefore have great potential for Bai Bang PPMS composting
Algorithm to Automatically Extract Body Sizes and Shapes
This study presents an algorithm to automatically extract the size and body shape of a 3D scanned model. The methods used in this research include factor analysis, linear regression equation, cluster analysis, and discriminant analysis. These are used to analyze the bodyâs shape and choose the best primary dimensions for establishing the sizing system table. Authors use fuzzy logic to establish the mathematical model. In this model, the input variables are the inseam height and the neck girth measurements, and the output variables are the numbers of the human size coding and body shape. In addition, the rotation matrix and the optimal function are used to write an algorithm to estimate the neck girth and inseam measurements. Furthermore, a simple approach based on vertices and surface normal vector data, together with optimal searching, is adapted to estimate the primary dimensions. This estimation algorithm, combined with the fuzzy logic model, makes the automated process of extracting the size and body shape possible. The findings of the study suggest a new research method for quickly informing people about their body shape. This supports purchasing clothes and designing tailored clothing. The automatic algorithm will be very useful for buying clothes face-to-face or online
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