923 research outputs found
Optimal Uncertainty Quantification
We propose a rigorous framework for Uncertainty Quantification (UQ) in which
the UQ objectives and the assumptions/information set are brought to the
forefront. This framework, which we call \emph{Optimal Uncertainty
Quantification} (OUQ), is based on the observation that, given a set of
assumptions and information about the problem, there exist optimal bounds on
uncertainties: these are obtained as values of well-defined optimization
problems corresponding to extremizing probabilities of failure, or of
deviations, subject to the constraints imposed by the scenarios compatible with
the assumptions and information. In particular, this framework does not
implicitly impose inappropriate assumptions, nor does it repudiate relevant
information. Although OUQ optimization problems are extremely large, we show
that under general conditions they have finite-dimensional reductions. As an
application, we develop \emph{Optimal Concentration Inequalities} (OCI) of
Hoeffding and McDiarmid type. Surprisingly, these results show that
uncertainties in input parameters, which propagate to output uncertainties in
the classical sensitivity analysis paradigm, may fail to do so if the transfer
functions (or probability distributions) are imperfectly known. We show how,
for hierarchical structures, this phenomenon may lead to the non-propagation of
uncertainties or information across scales. In addition, a general algorithmic
framework is developed for OUQ and is tested on the Caltech surrogate model for
hypervelocity impact and on the seismic safety assessment of truss structures,
suggesting the feasibility of the framework for important complex systems. The
introduction of this paper provides both an overview of the paper and a
self-contained mini-tutorial about basic concepts and issues of UQ.Comment: 90 pages. Accepted for publication in SIAM Review (Expository
Research Papers). See SIAM Review for higher quality figure
Lactobacillus plantarum CUL66 can impact cholesterol homeostasis in Caco-2 enterocytes
Hypercholesterolemia drives the development of cardiovascular disease, the leading cause of mortality in western society. Supplementation with probiotics that interfere with cholesterol metabolism may provide a contribution to disease prevention. Lactobacillus plantarum CUL66 (NCIMB 30280) has been assessed in vitro for its ability to impact cholesterol absorption. L. plantarum CUL66 tested positive for bile salt hydrolase activity and the ability to assimilate cholesterol from culture media. RT-qPCR analysis showed that the bacterium significantly decreased the expression of Niemann-Pick C1-like 1 and ATP-binding cassette transporter-1 in polarised Caco-2 cells after 6 h exposure. Conversely, the expression of ATP-binding cassette sub-family G member (ABCG)-5 and ABCG-8, and 3-hydroxy-3-methylglutaryl-CoA reductase were significantly increased. Using a radiolabelled assay, we also observed significant reductions in the uptake and basolateral efflux of cholesterol by Caco-2 cells exposed to L. plantarum CUL66. This in vitro study identified L. plantarum CUL66 as a cholesterol lowering bacteria by highlighting its ability to beneficially regulate multiple in vitro events associated with intestinal cholesterol metabolism and provides evidence of efficacy for its inclusion in future in vivo studies
Phase transition in the Sznajd model with independence
We propose a model of opinion dynamics which describes two major types of
social influence -- conformity and independence. Conformity in our model is
described by the so called outflow dynamics (known as Sznajd model). According
to sociologists' suggestions, we introduce also a second type of social
influence, known in social psychology as independence. Various social
experiments have shown that the level of conformity depends on the society. We
introduce this level as a parameter of the model and show that there is a
continuous phase transition between conformity and independence
Enhancing methane production from the invasive macroalga Rugulopteryx okamurae through anaerobic co-digestion with olive mill solid waste: process performance and kinetic analysis
The biomass valorisation of the invasive brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) is key to curbing the expansion of this invasive macroalga which is generating tonnes of biomass on southern Spain beaches. As a feasible alternative for the biomass management, anaerobic co-digestion is proposed in this study. Although the anaerobic digestion of macroalgae barely produced 177 mL of CH4 g−1 VS, the co-digestion with a C-rich substrate, such as the olive mill solid waste (OMSW, the main waste derived from the two-phase olive oil manufacturing process), improved the anaerobic digestion process. The mixture improved not only the methane yield, but also its biodegradability. The highest biodegradability was found in the mixture 1 R. okamurae—1 OMSW, which improved the biodegradability of the macroalgae by 12.9% and 38.1% for the OMSW. The highest methane yield was observed for the mixture 1 R. okamurae—3 OMSW, improving the methane production of macroalgae alone by 157% and the OMSW methane production by 8.6%. Two mathematical models were used to fit the experimental data of methane production time with the aim of assessing the processes and obtaining the kinetic constants of the anaerobic co-digestion of different combination of R. okamurae and OMSW and both substrates independently. First-order kinetic and the transference function models allowed for appropriately fitting the experimental results of methane production with digestion time. The specific rate constant, k (first-order model) for the mixture 1 R. okamurae- 1.5 OMSW, was 5.1 and 1.3 times higher than that obtained for the mono-digestion of single OMSW and the macroalga, respectively. In the same way, the transference function model revealed that the maximum methane production rate (Rmax) was also found for the mixture 1 R. okamurae—1.5 OMSW (30.4 mL CH4 g−1 VS day−1), which was 1.6 and 2.2 times higher than the corresponding to the mono-digestions of the single OMSW and sole R. okamurae (18.9 and 13.6 mL CH4 g−1 VS day−1), respectively.Ministerio de Ciencia e Innovación PID2020-114975RB-10
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Can Male Circumcision Have an Impact on the HIV Epidemic in Men Who Have Sex with Men?
Background: Three trials have demonstrated the prophylactic effect of male circumcision (MC) for HIV acquisition among heterosexuals, and MC interventions are underway throughout sub-Saharan Africa. Similar efforts for men who have sex with men (MSM) are stymied by the potential for circumcised MSM to acquire HIV easily through receptive sex and transmit easily through insertive sex. Existing work suggests that MC for MSM should reach its maximum potential in settings where sexual role segregation is historically high and relatively stable across the lifecourse; HIV incidence among MSM is high; reported willingness for prophylactic circumcision is high; and pre-existing circumcision rates are low. We aim to identify the likely public health impact that MC interventions among MSM would have in one setting that fulfills these conditions—Peru—as a theoretical upper bound for their effectiveness among MSM generally. Methods and Findings: We use a dynamic, stochastic sexual network model based in exponential-family random graph modeling and parameterized from multiple behavioral surveys of Peruvian MSM. We consider three enrollment criteria (insertive during 100%, >80% or >60% of UAI) and two levels of uptake (25% and 50% of eligible men); we explore sexual role proportions from two studies and different frequencies of switching among role categories. Each scenario is simulated 10 times. We estimate that efficiency could reach one case averted per 6 circumcisions. However, the population-level impact of an optimistic MSM-MC intervention in this setting would likely be at most ∼5–10% incidence and prevalence reductions over 25 years. Conclusions: Roll-out of MC for MSM in Peru would not result in a substantial reduction in new HIV infections, despite characteristics in this population that could maximize such effects. Additional studies are needed to confirm these results for other MSM populations, and providers may consider the individual health benefits of offering MC to their MSM patients
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Madness and Mindfulness: How the "Personal" is "Political"
The chapter examines the institutionalization of unreason and the potential role of meditation in disclosing its roots. It is argued that meditative awareness can enable critical reflection on, and transformation of, practices that diminish our rational awareness. Mindfulness may contribute to this awareness, but its lack of an ethical frame renders it vulnerable to narcissistic appropriation and corporate commercialization. Accordingly, mindfulness is limited in disclosure, and counteracting, of the needless perpetuation of suffering associated with ego-building and defensive emotions, as manifest in contemporary expressions of sectarianism and fanaticism. The examination of antidotes to unreason and freedom is accomplished through a series of critical reflections upon the insights generated by Wright Mills’ The Sociological Imagination, Carol Hanisch’s “The Personal is Political,” and Freire’s Pedagogy of the Oppressed. These texts provide complementary commentaries on the development of progressive, emancipatory consciousness and praxis to which, I conjecture, meditation, as distinct from the mindfulness movement, contributes
Recommended from our members
Madness and Mindfulness
The chapter examines the institutionalization of unreason and the potential role of meditation in disclosing its roots. It is argued that meditative awareness can enable critical reflection on, and transformation of, practices that diminish our rational awareness. Mindfulness may contribute to this awareness, but its lack of an ethical frame renders it vulnerable to narcissistic appropriation and corporate commercialization. Accordingly, mindfulness is limited in disclosure, and counteracting, of the needless perpetuation of suffering associated with ego-building and defensive emotions, as manifest in contemporary expressions of sectarianism and fanaticism. The examination of antidotes to unreason and freedom is accomplished through a series of critical reflections upon the insights generated by Wright Mills’ The Sociological Imagination, Carol Hanisch’s “The Personal is Political,” and Freire’s Pedagogy of the Oppressed. These texts provide complementary commentaries on the development of progressive, emancipatory consciousness and praxis to which, I conjecture, meditation, as distinct from the mindfulness movement, contributes
Evaluation of batch mesophilic anaerobic digestion of raw and trampled llama and dromedary dungs: methane potential and kinetic study
Funding for open access publishing: Universidad Pablo de Olavide/CBUA. This study was funded y the project FEDER UPO-1380782 financed by the regional government of Andalucía, Junta de Andalucía, Consejería de Trasformación Económica, Industria, Conocimiento y Universidades and the project PID2020-114975RB-100/AEI/10.13039/501100011033 financed by the Spanish Ministry of Science and Innovation.This research was carried out with the aim to evaluate the anaerobic digestion (AD) of llama and dromedary dungs (both untreated and trampled) in batch mode at mesophilic temperature (35 °C). The biochemical methane potential (BMP) tests with an inoculum to substrate ratio of 2:1 (as volatile solids (VS)) were carried out. The methane yield from trampled llama dung (333.0 mL CH4 g¿1 VSadded) was considerably higher than for raw llama, raw and trampled dromedary dungs (185.9, 228.4, 222.9 mL CH4 g¿1 VSadded, respectively). Therefore, trampled llama dung was found to be the best substrate for methane production due to its high content of volatile solids as well as its high nitrogen content (2.1%) and more appropriate C/N ratio (23.6) for AD. The experimental data was found to be in accordance with both first-order kinetic and transference function mathematical models, when evaluating the experimental methane production against time. By applying the first-order kinetic model, the hydrolysis rate constants, kh, were found to be 19% and 11% higher for trampled dungs in comparison with the raw dung of dromedary and llama, respectively. In addition, the maximum methane production rate (Rm) derived from the transference function model for trampled llama dung (22.0 mL CH4 g¿1 VS d¿1) was 83.3%, 24.4% and 22.9% higher than those obtained for raw llama manure and for raw and trampled dromedary dungs, respectively.Universidad Pablo de Olavide de Sevilla. Departamento de Sistemas Físicos, Químicos y Naturale
Yield Evaluation of Nutrient-rich Potato Clones in High Hill of Nepal
A study was conducted to evaluate the yield of nutrient-rich potato clones in high-hill districts: Dolakha and Jumla of Nepal during the years 2013 and 2014, respectively. Fourteen potato clones were tested as on-station and on-farm experiments at both districts, and those fourteen clones were compared to ‘Lady Rosita' and ‘Jumli Local' respectively as the check varieties in the first year experiment, 2013. Eight promising clones were selected from the first year experiment, and were evaluated and compared with same local varieties in the consecutive year, 2014. Two clones namely; CIP 395112.32 (19.3 tha-1) and CIP 393073.179 (17.8 tha-1) exhibited superior marketable tuber yield than that of ‘Lady Rosita'(14.2 tha-1) in Dolakha and five CIP clones namely; 395112.32 (25.5 tha-1), 393073.179 (22.5 tha-1), 394611.112 (20.9 tha-1), 390478.9 (19.9 tha-1) and 395017.229 (17.0 tha-1) showed higher marketable tuber yield than ‘Jumli Local'(14.5 tha-1). Based on two years' phenotypic and tuber yield result, clones CIP 395112.32 and CIP 393073.179 are recommended to potato growers at high hills of Nepal for commercial cultivation.Journal of Nepal Agricultural Research Council Vol.3 2017: 6-1
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