1,245 research outputs found
Epidemic model on a network: analysis and applications to COVID-19
We analyze an epidemic model on a network consisting of
susceptible-infected-recovered equations at the nodes coupled by diffusion
using a graph Laplacian. We introduce an epidemic criterion and examine
different vaccination/containment strategies: we prove that it is most
effective to vaccinate a node of highest degree. The model is also useful to
evaluate deconfinement scenarios and prevent a so-called second wave. The model
has few parameters enabling fitting to the data and the essential ingredient of
importation of infected; these features are particularly important for the
current COVID-19 epidemic
Proposal for applying combined selection to diallel analysis.
The phylosophy of intrapopulation combined selection is the search for and identification of individuals with superior genotypic behavior, based on their performance compared to the family mean and, at the same time, of their family mean in relation to the population mean, through the weighting of the phenotypic values represented, respectively, by the within and among families heritability coeficient. The objective of this study was to adapt and apply this philosophy ti diallel analysis. The crosses were considered as having fixed effects and selected on the basis of their specific combining ability (SCA), and on the mean performance of the two involved parents, in relation to the general combining ability (GCA). This work was based on Griffing's (Heredity 10; 35-50, 1956) method 2, model 1 which involves p(p+1)/2 treatments. The proposed index result from the weighting of the effects of GCA (gi's) and SCA (sij's) by the respective determination coefficient of additive and dominant genetic determinations, resulting from the partitioning of the total genotypic determination coefficient. An example is given for illustration
Implementation of the Water Framework Directive in an outermost EU region : the case of Azores archipelago
The Azores Water Plan (AWP) came to force in year 2003 in order to provide a coherent set of measures to protect and enhance water resources in the archipelago. The AWP was developed according to EU Water Framework Directive (WFD) and a close relationship can be found between goals on both documents. The evaluation of results associated to AWP implementation, made possible through a consultation procedure described in the present paper, provides an indirect assessment of the implementation of the WFD in an EU outermost region such as the Azores. The analysis suggests that major constrains to the full implementation of the AWP and WFD are associated with administrative arrangements, reflected in a lack of coordination, as well as adequate funding and cost recovery and strategies for public participation and information provision. Instead, water quality monitoring is already fully operational showing a strong relationship between science and water policy
Prospective scenarios for water quality and ecological status in Lake Sete Cidades (Portugal) : the integration of mathematical modelling in decision processes
The design of alternative strategies for water and ecological quality protection at the Lake
Verde of Sete Cidades should be coupled with the assessment of future trophic states.
Therefore, a mathematical model was developed to make prospective scenarios to reduce
the risk of environmental degradation of the lake, and a modified Psenner scheme was used
to characterize P distribution in the sediments. The model was able to describe thermal
stratification, nutrient cycling (P, NH4 and NO3), dissolved O2, and phytoplankton dynamics
in the water column and adjacent sediment layers. Internal P recycling, resulting from thermal
stratification and sediment anoxia, was identified as the main cause for the increase of
P concentration in the hypolimnion followed by slow transfer to the epilimnion (about
20 lg/L annual average). Cyanobacteria blooms during spring were explained by the availability
of P and increased water temperature verified during this season. The most sensitive
model parameter was sediment porosity. This parameter has a direct effect in dissolved O2
and P profiles and also in phytoplankton biomass. Finally, different water quality restoration
scenarios were identified and their effectiveness assessed. Without the adoption of
remediation measures (scenario control), Lake Verde water quality would deteriorate with
annual average concentrations of total P and phytoplankton biomass (dry matter) reaching
34 lg/L and 2 mg/L, respectively, after 10 years of simulation. The reduction of P loads (scenario
PORAL) into the lake would improve water quality comparatively to the scenario control,
reducing the annual average concentrations of total P from 34 lg/L to 26 lg/L and of
phytoplankton from 2 mg/L down to 1.4 mg/L after 10 years of simulation. In scenario sediments,
corresponding to a decrease in the organic content of the sediments, a reduction in
the concentrations of total P and phytoplankton is expected in the first two years of simulation,
but this effect, would be attenuated throughout the years due to organic matter
sedimentation. The best strategy is obtained by combining external and internal measures
for P remediation. Finally, it is recommended that the model be used to integrate the
results of water quality monitoring and watershed management plans.Regional
Department of Water Resources and Land Planning; Regional Secretary of Environment
and Sea; Science and Technology
Foundation
Electrochemical chemically based sensors and emerging enzymatic biosensors for antidepressant drug detection: a review
Major depressive disorder is a widespread condition with antidepressants as the main pharmacological treatment. However, some patients experience concerning adverse reactions or have an inadequate response to treatment. Analytical chromatographic techniques, among other techniques, are valuable tools for investigating medication complications, including those associated with antidepressants. Nevertheless, there is a growing need to address the limitations associated with these techniques. In recent years, electrochemical (bio)sensors have garnered significant attention due to their lower cost, portability, and precision. Electrochemical (bio)sensors can be used for various applications related to depression, such as monitoring the levels of antidepressants in biological and in environmental samples. They can provide accurate and rapid results, which could facilitate personalized treatment and improve patient outcomes. This state-of-the-art literature review aims to explore the latest advancements in the electrochemical detection of antidepressants. The review focuses on two types of electrochemical sensors: Chemically modified sensors and enzyme-based biosensors. The referred papers are carefully categorized according to their respective sensor type. The review examines the differences between the two sensing methods, highlights their unique features and limitations, and provides an in-depth analysis of each sensor.info:eu-repo/semantics/publishedVersio
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