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1.
Adv Exp Med Biol ; 1232: 307-313, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893425

RESUMO

Near infrared optical tomography (NIROT) is a non-invasive imaging technique to provide physiological information e.g. the oxygenation of tissue. For image reconstruction in clinical and preclinical scenarios, models to accurately describe light propagation are needed. This work aims to assess the accuracy and efficiency of different models, which paves the way for an optimal design of model-based image reconstruction algorithms in NIROT for realistic tissue geometries and heterogeneities. Two popular simulators were evaluated: the Monte Carlo (MC) method based MCX and the finite element method (FEM) based Toast++. We compared simulated results with experimental data measured on a homogeneous silicone phantom with well-calibrated parameters. The laser light was focused on the center of the phantom surface and images were captured by a CCD camera in both reflection and transmission modes. For transmittance measurements, the two models showed good agreement. Both achieve a cosine similarity of ~99%. In contrast, for reflectance measurements, FEM results deviated more from the measured values than MC, yielding similarity values of 86% and 94%, respectively. This study recommends the use of MC for NIROT in reflection mode and both MC and FEM yield excellent results for transmission mode.


Assuntos
Análise de Elementos Finitos , Modelos Teóricos , Método de Monte Carlo , Tomografia Óptica , Algoritmos , Simulação por Computador , Análise de Elementos Finitos/normas , Luz , Imagens de Fantasmas
2.
Chemosphere ; 240: 124906, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31550587

RESUMO

Benzene homologues have significant toxic effects to aquatic organisms. In this study, the acute toxicity data of benzene, toluene, ethylbenzene and xylene (BTEX) were collected and screened, and the toxicity extrapolation model of paired BTEX was established. The results showed that except the correlation between benzene and xylene was not strong due to insufficient data, the linear correlation of the other five paired BTEX was good (p < 0.01), and R2 fitted by the four out of five paired BTEX was greater than 0.85. The cross validation showed that ethylbenzene-xylene model was optimal, and for most species (81.8%), the established five BTEX models had a prediction error of less than 10%. Also, these extrapolation models were validated by experimental results of Pseudorasbora parva. The difference between the predicted and measured values of the acute toxicity of BTEX was less than 1 fold, which indicated that the extrapolation model had high accuracy.


Assuntos
Benzeno/toxicidade , Ecotoxicologia/métodos , Tolueno/toxicidade , Poluentes Químicos da Água/toxicidade , Xilenos/toxicidade , Animais , Organismos Aquáticos , Derivados de Benzeno/toxicidade , Biodegradação Ambiental , Cyprinidae , Modelos Teóricos , Reprodutibilidade dos Testes , Testes de Toxicidade Aguda
3.
Chemosphere ; 240: 124923, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726605

RESUMO

The purpose of this study is to deepen the knowledge of the various emission phenomena present in aerated tanks, widely used systems for municipal and industrial wastewater treatment. In order to investigate the emission mechanism, a specific model was developed. The theoretical model proposes to consider three different contributions to the emission of organic compounds from aerated wastewater tanks: the convection due to the sweep air flow rate, the rising bubbles stripping and the aerosol formation and successive evaporation. To compare the modeled results, an experimental campaign was conducted with two different solutes, acetone and butanol. The sampling was carried out with a Wind Tunnel system and the outflow gas samples were analysed with gas chromatographic technique. Moreover, this study investigates the dependence of the concentration in the gaseous phase from the speed of the air on the surface (1-5 cm/s) and from the flow of air diffused inside the liquid body (50-200 L/h). The empirical data were compared with theoretical curves. The results confirm two facts: the gas solute concentration decreases as the air velocity increases and, instead, increases with the air flow diffused through the tank.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Modelos Teóricos , Compostos Orgânicos/análise , Aerossóis/análise , Veículos Automotores , Águas Residuárias/análise
4.
Chemosphere ; 239: 124748, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520971

RESUMO

A total of 100 samples were collected from the sediments of a typical copper mining area, south China. Leaching concentrations of selected heavy metals (Ni, Cd, Cu, Pb, Zn, Ba, As, and Hg) were measured to evaluate their distribution patterns and associated health risk. Leaching concentrations of Cu (3.58 ±â€¯1.49 mg/L), Pb (1.50 ±â€¯1.06 mg/L), and Zn (4.04 ±â€¯1.68 mg/L) were significantly higher than the other metals in the samples. By evaluating the spatial heterogeneity, it was found that leaching metal concentrations did not decrease with environmental gradients, mostly caused by diverse distribution in pollution sources. The hazard index and carcinogenic risk indices showed significant risks of human exposure. For public safety, priority governance should be given to the main pollutants (Cd, Cu, Pb, Zn, and As) in sediments. In future studies, the integrated data will be urgently required for local stakeholders to conduct environmental monitoring and remediation scenarios.


Assuntos
Sedimentos Geológicos/análise , Metais Pesados/análise , Mineração , Poluentes do Solo/análise , Poluentes Químicos da Água/toxicidade , Carcinógenos/toxicidade , China , Cobre , Exposição Ambiental/efeitos adversos , Monitoramento Ambiental , Humanos , Metais Pesados/toxicidade , Modelos Teóricos , Saúde Pública , Medição de Risco , Poluentes do Solo/toxicidade , Poluentes Químicos da Água/análise
5.
Chemosphere ; 240: 124928, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31563101

RESUMO

Oxidation is an attractive treatment method to effectively remove organic contaminants in water. In this study, degradation of 30 organic compounds in different oxidation systems was evaluated, including oxygen (O2), hydrogen peroxide (H2O2), ozone (O3) and hydroxyl radical (HO). First, a quantitative structure-activity relationship (QSAR) model for oxidation-reduction potentials (ORPs) of organics was developed and exhibited a good performance to predict ORP values of organics with evaluation indices of squared correlation coefficient (R2) = 0.866, internal validation (q2) = 0.811 and external validation (Qext2) = 0.669. Four quantum parameters, including f(+)n, f(-)n, EHOMO and EB3LYP dominate the ORP values. Subsequently, a relationship between reaction rates (k) and the difference of ORP for oxidants and organics (ΔEoxi-org) was established, however, which was limited (R2= 0.697). Therefore, two new predictors (slopes and intercepts) are proposed based on the linear relationships between k values and ORPs of oxidants. These new predictors can be applied to estimate the reaction rates and minimum oxidation potential for organic compounds. Afterwards, to express the two predictors, QSAR models were established. The two optimal QSAR models fitted very well with experimental values and were demonstrated to be stable and accurate based on R2 (0.982 and 0.965), q2 (0.950 and 0.950) and Qext2 (0.985 and 0.989). BOx, q(H)+ and q(C)x were main factors influencing the slopes and intercepts. This study developed methods to predict ORPs of organics and established two new predictors to estimate the reaction rates undergoing different oxidation processes, offering new insights into the oxidant selection.


Assuntos
Modelos Teóricos , Compostos Orgânicos/análise , Relação Quantitativa Estrutura-Atividade , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Oxidantes/química , Oxirredução , Oxigênio/química , Ozônio/química , Águas Residuárias/química , Água
6.
J Sci Food Agric ; 100(2): 453-464, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31487397

RESUMO

Operative planning in agricultural production has historically had the objective of improving yields and quality. Sowing, cropping, and harvesting are usually treated independently, and waste and the sustainability of operations are generally not integrated into operational planning methodologies for agricultural production. This study shows the need to have a clear and precise methodology to minimize waste in agricultural production systems to ensure sustainability. This need is addressed with a novel methodological guide to minimizing waste in agricultural operations, crop maintenance, and harvesting. The proposed methodology is founded on the use of lean manufacturing as a waste-management tool. Lean manufacturing principles allow agricultural operations and the variables that represent wastes to be identified, mathematical models to be built, constraints to be defined, and the cost of waste to be illustrated, as well as its minimization through an objective function. To guide implementation, we propose a conceptual model to explain the construction of a mathematical model that represents the development of decision variables on agricultural operations with the elements to consider and the constraints and theoretical proposal of the necessary objective function. The proposed conceptual model and the constructed methodology constitute a novel development within agricultural production systems that could be used by decision makers and farmers. © 2019 Society of Chemical Industry.


Assuntos
Agricultura/métodos , Resíduos/análise , Agricultura/economia , Modelos Teóricos , Resíduos/economia
7.
Ecol Lett ; 23(1): 193-207, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31692214

RESUMO

The hypothesis that environmental heterogeneity promotes species richness by increasing opportunities for niche partitioning is a fundamental paradigm in ecology. However, recent studies suggest that heterogeneity-diversity relationships (HDR) are more complex than expected from this niche-based perspective, and often show a decrease in richness at high levels of heterogeneity. These findings have motivated ecologists to propose new mechanisms that may explain such deviations. Here we provide an overview of currently recognised mechanisms affecting the shape of HDRs and present a conceptual model that integrates all previously proposed mechanisms within a unified framework. We also translate the proposed framework into an explicit community dynamic model and use the model as a tool for generating testable predictions concerning how landscape properties interact with species traits in determining the shape of HDRs. Our main finding is that, despite the enormous complexity of such interactions, the predicted HDRs are rather simple, ranging from positive to unimodal patterns in a highly consistent and predictable manner.


Assuntos
Biodiversidade , Ecossistema , Ecologia , Modelos Teóricos
8.
Phys Chem Chem Phys ; 22(3): 1511-1524, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31872826

RESUMO

The transcriptional regulator TtgR belongs to the TetR family of transcriptional repressors. It depresses the transcription of the TtgABC operon and itself and thus regulates the extrusion of noxious chemicals with efflux pumps in bacterial cells. As the ligand-binding domain of TtgR is rather flexible, it can bind with a number of structurally diverse ligands, such as antibiotics, flavonoids and aromatic solvents. In the current work, we perform equilibrium and nonequilibrium alchemical free energy simulation to predict the binding affinities of a series of ligands targeting the TtgR protein and an agreement between the theoretical prediction and the experimental result is observed. End-point methods MM/PBSA and MM/GBSA are also employed for comparison. We further study the interaction maps and contacts between the protein and the ligand and identify important interactions in the protein-ligand binding cases. The dynamics fluctuation and secondary structures are also investigated. The current work sheds light on atomic and thermodynamic understanding of the TtgR-ligand interactions.


Assuntos
Modelos Teóricos , Proteínas Repressoras/metabolismo , Termodinâmica , Simulação por Computador , Ligantes , Ligação Proteica
9.
Chemosphere ; 238: 124604, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31450113

RESUMO

Accurate in silico predictions of chemical substance ecotoxicity has become an important issue in recent years. Most conventional methods, such as the Ecological Structure-Activity Relationship (ECOSAR) model, cluster chemical substances empirically based on structural information and then predict toxicity by employing a log P linear regression model. Due to empirical classification, the prediction accuracy does not improve even if new ecotoxicity test data are added. In addition, most of the conventional methods are not appropriate for predicting the ecotoxicity on inorganic and/or ionized compounds. Furthermore, a user faces difficulty in handling multiple Quantitative Structure-Activity Relationship (QSAR) formulas with one chemical substance. To overcome the flaws of the conventional methods, in this study a new method was developed that applied unsupervised machine learning and graph theory to predict acute ecotoxicity. The proposed machine learning technique is based on the large AIST-MeRAM ecotoxicity test dataset, a software program developed by the National Institute of Advanced Industry Science and Technology for Multi-purpose Ecological Risk Assessment and Management, and the Molecular ACCess System (MACCS) keys that vectorize a chemical structure to 166-bit binary information. The acute toxicity of fish, daphnids, and algae can be predicted with good accuracy, without requiring log P and linear regression models in existing methods. Results from the new method were cross-validated and compared with ECOSAR predictions and show that the new method provides better accuracy for a wider range of chemical substances, including inorganic and ionized compounds.


Assuntos
Ecotoxicologia/métodos , Aprendizado de Máquina , Poluentes Químicos da Água/toxicidade , Poluição Química da Água/análise , Animais , Simulação por Computador , Daphnia/efeitos dos fármacos , Peixes , Modelos Lineares , Modelos Teóricos , Relação Quantitativa Estrutura-Atividade , Medição de Risco/métodos , Software , Poluentes Químicos da Água/química
10.
Sci Total Environ ; 699: 134277, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31689668

RESUMO

Oil sands developments release acidifying compounds (SO2 and NO2) with the potential for acidifying deposition and impacts to forest health. This article integrates the findings presented in the Oil Sands Forest Health Special Issue, which reports on the results of 20 years of forest health monitoring, and addresses the key questions asked by WBEA's Forest Health Monitoring (FHM) Program: 1) is there evidence of deposition affecting the environment?, 2) have there been changes in deposition or effects over time?, 3) do acid deposition levels require management intervention?, 4) what are major sources of deposited substances? and 5) how can the program be improved? Deposition of sulphur, nitrogen, base cations (BC), polycyclic aromatic compounds and trace elements decline exponentially with distance from sources. There is little evidence for acidification effects on forest soils or on understory plant communities or tree growth, but there is evidence of nitrogen accumulation in jack pine needles and fertilization effects on understory plant communities. Sulphur, BC and trace metal concentrations in lichens increased between 2008 and 2014. Source apportionment studies suggest fugitive dust in proximity to mining is a primary source of BC, trace element and organic compound deposition, and BC deposition may be neutralizing acidifying deposition. Sulphur accumulation in soils and nitrogen effects on vegetation may indicate early stages of acidification. Deposition estimates for sites close to emissions sources exceed proposed regulatory trigger levels, suggesting a detailed assessment of acidification risk close to the emission sources is warranted. However, there is no evidence of widespread acidification as suggested by recent modeling studies, likely due to high BC deposition. FHM Program evolution should include continued integration with modeling approaches, ongoing collection and assessment of monitoring data and testing for change over time, and addition of monitoring sites to fill gaps in regional coverage.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Florestas , Campos de Petróleo e Gás , Líquens , Modelos Teóricos , Nitrogênio/análise , Compostos Orgânicos , Pinus , Enxofre/análise , Árvores
11.
Ann Otol Rhinol Laryngol ; 129(1): 70-77, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31510765

RESUMO

OBJECTIVE: Prediction and early intervention for hypocalcemia following parathyroidectomy and total thyroidectomy can decrease hospital cost and prevent severe hypocalcemia-related complications. This study aims to predict the severity of hypocalcemia after parathyroidectomy or thyroidectomy and to stratify patients into groups with different levels of risk for developing severe hypocalcemia, so that higher risk patients may be monitored more closely and receive earlier interventions. METHODS: This was a retrospective cohort study of 100 patients with primary hyperparathyroidism who underwent parathyroidectomy as the primary treatment modality at a tertiary care hospital. Clinical information, including demographic information, perioperative PTH and calcium levels, vitamin D levels, weight of the pathologic glands removed, gland pathology, and re-admission rates, were retrieved. Statistical analysis was performed to analyze the association between collected variables and percentage of calcium drop following parathyroidectomy with statistical significant set at P-values <0.05. RESULTS: Age, sex, and vitamin D level provided very minimal information to quantify risks of postoperative hypocalcemia. The percentage of decrease from preoperative PTH level to the lowest PTH level after the removal of the abnormal gland(s) is the most significant predicting factor for the severity of postoperative hypocalcemia. There is a mathematic regressional correlation between them. A formula was generated to quantify this linear relationship between them, and the nadir calcium can be calculated as Canadir=Capreop*[1-0.35*(PTHpreop-PTHintraop)2PTHpreop2], where Canadir = the lowest postoperative calcium level, and PTHintraop = PTH level 15 minutes after removal of the abnormal gland, with the value of R2 > 0.7. The formula has been tested primarily in our patient population with good reliability. CONCLUSIONS: The highest preoperative, lowest postoperative, and change in PTH level can help us reliably calculate the trend of postoperative calcium level. Decision to pursue early interventions can be made based on the calculated result from the formula we obtained.


Assuntos
Hiperparatireoidismo Primário/cirurgia , Hipocalcemia/epidemiologia , Paratireoidectomia , Complicações Pós-Operatórias/epidemiologia , Adenoma/sangue , Adenoma/patologia , Adenoma/cirurgia , Adulto , Fatores Etários , Feminino , Humanos , Hiperparatireoidismo Primário/sangue , Hipocalcemia/sangue , Hipocalcemia/terapia , Período Intraoperatório , Magnésio/sangue , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Hormônio Paratireóideo/sangue , Neoplasias das Paratireoides/sangue , Neoplasias das Paratireoides/patologia , Neoplasias das Paratireoides/cirurgia , Complicações Pós-Operatórias/sangue , Período Pós-Operatório , Período Pré-Operatório , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Fatores Sexuais , Tireoidectomia , Carga Tumoral , Vitamina D/sangue
12.
J Environ Manage ; 254: 109750, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31726279

RESUMO

Decision-making associated with the promotion of water sustainability is subjected to uncertainties arising, on the one hand, from the current capacity of understanding socio-environmental systems and their temporality, complexity and multidimensionality; and, on the other hand, from the need to represent key aspects of these systems through data and information. Such a representation is often supported by indicators, indices and systems of indicators for relevant aspects of the problem and for a scenario under analysis. In this context, the main aim of this study was to develop a novel system of indicators for water sustainability assessment in river basins. Literature review and content analysis were used to define an analytical structure for the problem from the perspective of the natural, social and built capitals of related sustainable development assessment. Each capital has been hierarchically subdivided into categories, subcategories and attributes, leading to 54 aspects for water sustainability assessment. A list of indicators was compiled from the scientific and technical literature, linked to attributes, and associated with valuation ranges. This led to the proposition of the River Basin Water Sustainability Index (RBWSI) and sub-indices associated with categories and subcategories of the model. The timeframe and territorial scale relevant for assessment were defined as five-to-ten year periods and areas under the jurisdiction of river basin management committees, respectively. The new model and index thus proposed may be useful in water sustainability diagnostic and prognostic studies, such as required to assess the effectiveness of river basin management actions aimed at promoting sustainable development.


Assuntos
Conservação dos Recursos Naturais , Água , Modelos Teóricos , Rios , Desenvolvimento Sustentável
13.
Rev Med Chil ; 147(5): 650-657, 2019 May.
Artigo em Espanhol | MEDLINE | ID: mdl-31859898

RESUMO

BACKGROUND: There is always a risk of importing infectious diseases when travelling abroad. AIM: To estimate the effective risk of a Chilean of acquiring measles during a travel by countries where measles outbreaks have been reported, considering the present level of immunity in the country. MATERIAL AND METHODS: Previously established mathematical models using differential equations were applied to calculate the risk of acquiring measles of people traveling to endemic areas. RESULTS: The probability of acquiring measles of a voyager is 8.11 x 10-8. CONCLUSIONS: These estimations help decision making about preventive measures for travelers to endemic measles areas.


Assuntos
Sarampo/transmissão , Modelos Teóricos , Medição de Risco/métodos , Doença Relacionada a Viagens , Chile/epidemiologia , Surtos de Doenças , Humanos , Sarampo/epidemiologia , Sarampo/prevenção & controle , Vacina contra Sarampo , Probabilidade , Fatores de Risco , Fatores de Tempo , Vacinação
14.
Wiad Lek ; 72(11 cz 1): 2089-2093, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31860852

RESUMO

OBJECTIVE: Introduction: To date, there are techniques that allow dental surgeons to restore the lost volume of bone mass, but the level of complications during augmentation remains consistently high. One of the main types of postoperative complications is the exposure of bone augmentate and its infection as a result of ischemic or destructive processes in the mucous shreds, which cover the augmentate, resulting from their overgrowth. The aim: The purpose of our research was to increase bone augmentation effectiveness in patients with secondary edentulism and to reduce risk of postoperative complications caused by ischemia of the mucous membranes because of their tension by mathematical simulation of tensile limits and permissible deformation for the mucous membranes of the oral cavity. PATIENTS AND METHODS: Materials and methods: As a research method was selected a two-component Mooney-Rivlin model, taking into account the indicators of elasticity and static strength of flat samples in tension, which allows them to perform hyperprime behavior at small and moderate deformations. For computer simulation of epithelial flap deformation during operation by finite element method we used ANSYS software environment. RESULTS: Results: Since elastic forces are potential, the work of forces does not depend on the way of tension. Only the initial and final states of the sample, i.e. its initial and final forms, play a role. CONCLUSION: Conclusions: The flap of 30 × 25 mm can be stretched and thus it is necessary to eliminate the deficit of fabric up to 5 mm wide in the direction of the Y axis (vertical axis). The relative elongation is λ = 25/20 = 1.25. The flap tension first occurs in the y direction.


Assuntos
Modelos Teóricos , Retalhos Cirúrgicos , Simulação por Computador , Elasticidade , Humanos , Boca
15.
Water Sci Technol ; 80(7): 1238-1248, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31850875

RESUMO

The frequent occurrence of sudden water pollution accidents has become a major threat to water environment safety. Although most researches have focused on constructing a pollutant source identification model and risk assessment methods for dealing with sudden water pollution accidents, a real-time, effective emergency measure for controlling pollutant diffusion, isolating and removing the pollutant, aiming at sudden water pollution accidents, has not been emphasized. Therefore, in this paper, a novel emergency approach of soft isolation was investigated to control pollution diffusion and decrease damage as soon as the accident occurred. In stage 1, the feature of pollution diffusion regarding a sudden water accident was predicted through a water quality model using computational fluid dynamics (CFD). Then, a design scheme of soft isolation was constructed in stage 2 to isolate the polluted zone and attention was paid to optimizing the parameters of soft isolation. Ultimately, the mathematical model of complete purification was formulated in stage 3 to remove the pollution from the impacted zone. The results indicated that the emergency measure of soft isolation could have significant potential to control and isolate pollution occurring in a sudden water pollution accident in the future.


Assuntos
Poluentes Químicos da Água , Poluição da Água , Acidentes , China , Modelos Teóricos , Qualidade da Água
16.
JAMA ; 322(18): 1806-1816, 2019 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-31714992

RESUMO

In recent years, many new clinical diagnostic tools have been developed using complicated machine learning methods. Irrespective of how a diagnostic tool is derived, it must be evaluated using a 3-step process of deriving, validating, and establishing the clinical effectiveness of the tool. Machine learning-based tools should also be assessed for the type of machine learning model used and its appropriateness for the input data type and data set size. Machine learning models also generally have additional prespecified settings called hyperparameters, which must be tuned on a data set independent of the validation set. On the validation set, the outcome against which the model is evaluated is termed the reference standard. The rigor of the reference standard must be assessed, such as against a universally accepted gold standard or expert grading.


Assuntos
Aprendizado de Máquina , Modelos Teóricos , Algoritmos , Humanos , Publicações , Sensibilidade e Especificidade
17.
J Emerg Manag ; 17(5): 403-432, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31736046

RESUMO

The increasing impacts of disasters, caused by more frequent extreme events coupled with the growth of adverse anthropogenic activities, has raised the importance of fostering more resilient communities. Measuring resilience is a vital step in the process of building and strengthening a community's resilience as it helps with identifying the priorities and monitoring the progress. The objective of the current research is to catalog variables proposed in the literature as measures of households' resilience to disasters. Searching the literature through content analysis and applying three selection criteria resulted in a list of 149 variables. These criteria required the variables to be influential on disaster resilience of households, to be quantitatively measurable, and to be obtainable from publicly available data sources. Additionally, a selection of resilience and vulnerability assessment models suggested in the literature were reviewed to highlight the importance of resilience variables in addressing their planned objectives. The variables were classified into five categories titled demographic, socioeconomic, infrastructural, environmental, and institutional. Further analysis of the variables led to identification of the most prevalent variables and commonalities among the categories, aimed to provide a more integrated approach toward resilience planning. This research can serve as an initial yet relatively extensive inventory for selecting variables that are deemed to be influential on households' resilience to extreme events. Further, quantifying a community's resilience using resilience variables can help with identifying and prioritizing the resilience needs, monitoring the progress, and justifying the costs of resilience programs.


Assuntos
Desastres , Resiliência Psicológica , Planejamento em Desastres , Humanos , Modelos Teóricos , Saúde Pública
18.
Phys Rev Lett ; 123(13): 138003, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31697550

RESUMO

We study the orientation statistics of spheroidal, axisymmetric microswimmers, with shapes ranging from disks to rods, swimming in chaotic, moderately turbulent flows. Numerical simulations show that rodlike active particles preferentially align with the flow velocity. To explain the underlying mechanism, we solve a statistical model via the perturbation theory. We show that such an alignment is caused by correlations of fluid velocity and its gradients along particle paths combined with fore-aft symmetry breaking due to both swimming and particle nonsphericity. Remarkably, the discovered alignment is found to be a robust kinematical effect, independent of the underlying flow evolution. We discuss its possible relevance for aquatic ecology.


Assuntos
Modelos Teóricos , Fenômenos Fisiológicos Bacterianos , Fenômenos Biomecânicos , Hidrodinâmica , Modelos Biológicos , Movimento (Física) , Natação
19.
Phys Rev Lett ; 123(15): 158006, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31702312

RESUMO

Microswimmers in nature often experience spatial gradients of viscosity. In this Letter we develop theoretical results for the dynamics of active particles, biological or otherwise, swimming through viscosity gradients. We model the active particles using the squirmer model, and show how viscosity gradients lead to viscotaxis for squirmers, and how the effects of viscosity gradients depend on the swimming gait of the microswimmers. We also show how such gradients in viscosity can be used to control active particles and suggest a mechanism to sort them based on their swimming style.


Assuntos
Modelos Teóricos , Chlamydomonas/fisiologia , Escherichia coli/fisiologia , Modelos Biológicos , Modelos Químicos , Natação , Viscosidade
20.
Phys Rev Lett ; 123(16): 163901, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31702361

RESUMO

When the feature size of photonic structures becomes comparable or even smaller than the wavelength of light, the fabrication imperfections inevitably introduce disorder that may eliminate many functionalities of subwavelength photonic devices. Here we suggest a novel concept to achieve a robust band gap which can endure disorder beyond 30% as a result of the transition from photonic crystals to Mie-resonant metamaterials. By utilizing Mie-resonant metamaterials with high refractive index, we demonstrate photonic waveguides and cavities with strong robustness to position disorder, thus providing a novel approach to the band-gap-based nanophotonic devices with new properties and functionalities.


Assuntos
Modelos Teóricos , Óptica e Fotônica/métodos , Fótons
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