1,662 research outputs found
Can Farmers and Bats Co-exist? Farmer Attitudes, Knowledge, and Experiences with Bats in Belize
Bats (Chiroptera) are often viewed negatively by the public. Negative public perceptions of bats may hinder efforts to conserve declining populations. In Belize, the presence of vampire bats (Desmodus rotundus and Diphylla ecaudata) exacerbates the potential for conflicts with humans because of the increased rabies transmission risks. To mitigate these risks, the Belize government provides farmers with assistance to trap and remove vampire bats. In June 2018, we surveyed farmers (n = 44) in and adjacent to the Vaca Forest Reserve in Belize to learn more about their attitudes, knowledge, and experiences with bats. This information may provide new insights and approaches to address farmers’ concerns and enhance bat conservation efforts in Belize. Farmers held negative attitudes toward bats, exhibited low knowledge of their ecosystem services, and supported the trapping and use of toxicants to control bat populations to reduce the risk of rabies transmission between vampire bats and livestock. Farmers with livestock had more negative attitudes toward bats than farmers without livestock. Despite farmers reporting depredation incidences with fruit-eating and vampire bats, farmers expressed more negative attitudes toward vampire bats. We recommend that conservation education efforts target all stakeholders in the reserve to increase awareness about the importance of bats to ecosystems and highlight the dangers of indiscriminate trapping. Cumulatively, this may lead to positive attitude changes toward bats and their conservation
Building Global Leaders through Field Research and Extension Experiences in Belize
One of the most complex agricultural and natural resources challenges of our time is reconciling sustainable global food security and biodiversity conservation. Providing undergraduate students effective, learning experiences to develop technical and cultural competency prepares them to address this challenge and become global leaders in their disciplines. A three-year experiential research and extension project brought together 14 students and 10 faculty mentors to investigate smallholder farmers practicing conservation-compatible adjacent to the Vaca Forest Reserve in Belize. We used an agroecological approach to foster systems-level thinking and develop transdisciplinary skills of undergraduate students. Students completed applied individual research projects that explored the challenge of food security and biodiversity conservation in the tropics, and worked collaboratively with local stakeholders, design and implement extension projects based on research results. Student and faculty teams assessed cropping and soil management practices; social and economic systems; and wildlife, forestry, and ecosystem services. We assessed student learning outcomes with a tool commonly used for evaluating undergraduate research. Students reported learning gains in attitudes and behaviors toward research, mindset towards research, ability to think and work like a scientist, and research skills. Students also reported positive working relationships with mentors and peers, and a high level of publication and presentation outputs. Students reported that their Belize experience helped develop their agroecological and cross-cultural knowledge and skills, and prepared them for their next career steps. We conclude with recommendations for higher education institutions wishing to develop meaningful global undergraduate research experiences that can build the next generation of leaders
Modeling of Transitional Channel Flow Using Balanced Proper Orthogonal Decomposition
We study reduced-order models of three-dimensional perturbations in
linearized channel flow using balanced proper orthogonal decomposition (BPOD).
The models are obtained from three-dimensional simulations in physical space as
opposed to the traditional single-wavenumber approach, and are therefore better
able to capture the effects of localized disturbances or localized actuators.
In order to assess the performance of the models, we consider the impulse
response and frequency response, and variation of the Reynolds number as a
model parameter. We show that the BPOD procedure yields models that capture the
transient growth well at a low order, whereas standard POD does not capture the
growth unless a considerably larger number of modes is included, and even then
can be inaccurate. In the case of a localized actuator, we show that POD modes
which are not energetically significant can be very important for capturing the
energy growth. In addition, a comparison of the subspaces resulting from the
two methods suggests that the use of a non-orthogonal projection with adjoint
modes is most likely the main reason for the superior performance of BPOD. We
also demonstrate that for single-wavenumber perturbations, low-order BPOD
models reproduce the dominant eigenvalues of the full system better than POD
models of the same order. These features indicate that the simple, yet accurate
BPOD models are a good candidate for developing model-based controllers for
channel flow.Comment: 35 pages, 20 figure
Multifidelity Monte Carlo estimation for large-scale uncertainty propagation
One important task of uncertainty quantification is propagating input uncertainties through a system of interest to quantify the uncertainties’ effects on the system outputs; however, numerical methods for uncertainty propagation are often based on Monte Carlo estimation, which can require large numbers of numerical simulations of the numerical model describing the system response to obtain estimates with acceptable accuracies. Thus, if the model is computationally expensive to evaluate, then Monte-Carlo-based uncertainty propagation methods can quickly become computationally intractable. We demonstrate that multifidelity methods can significantly speedup uncertainty propagation by leveraging low-cost low-fidelity models and establish accuracy guarantees by using occasional recourse to the expensive high-fidelity model. We focus on the multifidelity Monte Carlo method, which is a multifidelity approach that optimally distributes work among the models such that the mean-squared error of the multifidelity estimator is minimized for a given computational budget. The multifidelity Monte Carlo method is applicable to general types of low-fidelity models, including projection-based reduced models, data-fit surrogates, response surfaces, and simplified-physics models. We apply the multifidelity Monte Carlo method to a coupled aero-structural analysis of a wing and a flutter problem with a high-aspect-ratio wing. The low-fidelity models are data-fit surrogate models derived with standard procedures that are built in common software environments such as Matlab and numpy/scipy. Our results demonstrate speedups of orders of magnitude compared to using the high-fidelity model alone.United States. Air Force. Office of Scientific Research. Multidisciplinary University Research Initiative (Award FA9550-15-1-0038
Multi-output multilevel best linear unbiased estimators via semidefinite programming
Multifidelity forward uncertainty quantification (UQ) problems often involve
multiple quantities of interest and heterogeneous models (e.g., different
grids, equations, dimensions, physics, surrogate and reduced-order models).
While computational efficiency is key in this context, multi-output strategies
in multilevel/multifidelity methods are either sub-optimal or non-existent. In
this paper we extend multilevel best linear unbiased estimators (MLBLUE) to
multi-output forward UQ problems and we present new semidefinite programming
formulations for their optimal setup. Not only do these formulations yield the
optimal number of samples required, but also the optimal selection of
low-fidelity models to use. While existing MLBLUE approaches are single-output
only and require a non-trivial nonlinear optimization procedure, the new
multi-output formulations can be solved reliably and efficiently. We
demonstrate the efficacy of the new methods and formulations in practical UQ
problems with model heterogeneity.Comment: 22 pages, 5 figures, 3 table
Pre-hospital risk factors for inpatient death from severe febrile illness in Malian children.
BACKGROUND: Inpatient case fatality from severe malaria remains high in much of sub-Saharan Africa. The majority of these deaths occur within 24 hours of admission, suggesting that pre-hospital management may have an impact on the risk of case fatality. METHODS: Prospective cohort study, including questionnaire about pre-hospital treatment, of all 437 patients admitted with severe febrile illness (presumed to be severe malaria) to the paediatric ward in Sikasso Regional Hospital, Mali, in a two-month period. FINDINGS: The case fatality rate was 17.4%. Coma, hypoglycaemia and respiratory distress at admission were associated with significantly higher mortality. In multiple logistic regression models and in a survival analysis to examine pre-admission risk factors for case fatality, the only consistent and significant risk factor was sex. Girls were twice as likely to die as boys (AOR 2.00, 95% CI 1.08-3.70). There was a wide variety of pre-hospital treatments used, both modern and traditional. None had a consistent impact on the risk of death across different analyses. Reported use of traditional treatments was not associated with post-admission outcome. INTERPRETATION: Aside from well-recognised markers of severity, the main risk factor for death in this study was female sex, but this study cannot determine the reason why. Differences in pre-hospital treatments were not associated with case fatality
Antibiotic prescription patterns for acute diarrhea in a hospital in Shanghai in 2016: a cross-sectional study
Background: Unnecessary antibiotic use increases the risk for antibiotic resistance. The rates of antibiotic use for upper respiratory infections are high in hospitals in China. Although most guidelines advise against the use of antibiotics for acute diarrhea, little is known about antibiotic use practices for acute diarrhea in China. Methods: A retrospective prescription review from a Shanghai hospital outpatient electronic health records system was conducted from 1 January 2016 to 30 December 2016. Records were included for adult patients. The microbial resistance seasonal data in 2016 were extracted. Chi-squared and multivariable logistic regression and adjusted odd ratio (aOR) were used to assess the relationships between demographic characteristics and antibiotic prescribing. Results: In total, there were 16,565 prescriptions, 16,060 prescriptions were included in the final analysis after excluding the follow up visits. There were 12,131 (76%) prescriptions with antibiotics prescribed. 5505 (45%) of the antibiotics prescribed were injectable. Of the antibiotics prescribed, levofloxacin was the most frequent (85%), followed by various cephalosporins (14%). Of the cephalosporin prescriptions, 3rd generation products were the most common (97%). Treatment with oral rehydration salts (ORS) was prescribed 34 (0.2%) times, probiotics were prescribed 3414 (21%) times and smectite was prescribed 2209 (14%) times. Multivariable regression analysis showed that those more likely to receive antibiotics were age 31-50 aOR 1.3 (1.1-1.4), p<0.001, evaluated in the late evening (11pm to 7am) aOR 2.6 (2.2-2.9) p<0.001, in the early evening (6pm-11pm) aOR 2.0 (1.8-2.2) p<0.001, in the summer (June-August) aOR 1.7 (1.5-1.9) p<0.001. At the same time, the Gram positive and Gram negative resistance rates to levofloxacin exceeded 40%, including 50% of E. coliisolates. Conclusion: High rates of antibiotic use were observed for acute diarrhea in this hospital. Given the inappropriateness of antibiotics for acute diarrhea and the nonsensical high rates of of intravenous levofloxacin use and the concurrent high rates of the levofloxacin resistance, a more effective antibiotic stewardship program is needed to improve patient outcomes, reduce costs, reinforce policy and address the underlying causes of antibiotic abuse.published_or_final_versio
Borane-Catalyzed C(sp<sup>3</sup>)–F Bond Arylation and Esterification Enabled by Transborylation
The exchange of one single amino acid at position 71 of the DR4 beta-chain leads to significant differences in antigen processing and presentation of a human autoantigen chaperoned by a member of the HSP70 family
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