Analysis of optimal lockdown in integral economic-epidemic model.

We analyze the optimal lockdown in an economic-epidemic model with realistic infectiveness distribution. The model is described by Volterra integral equations and accurately depicts the COVID-19 infectivity pattern from clinical data. A maximum principle is derived, and a qualitative dynamic analysis of the optimal lockdown problem is provided over finite and infinite horizons.

Model with transmission delays for COVID-19 control: Theory and empirical assessment.

The paper focuses on modeling of public health measures to control the COVID-19 pandemic. The authors suggest a flexible integral model with distributed lags, which realistically describes COVID-19 infectiousness period from clinical data. It contains susceptible-infectious-recovered (SIR), susceptible-exposed-infectious-recovered (SEIR), and other epidemic models as special cases.

Optimal harvesting in forestry: steady-state analysis and climate change impact.

We perform the steady-state analysis of a nonlinear partial differential equation model that describes the dynamics of a managed size-structured forest. The harvesting policy is to maximize the net benefits from timber production over an infinite planning horizon. The existence and uniqueness of the steady-state trajectories are analysed.

Eight independent nuclear genes support monophyly of the plovers: the role of mutational variance in gene trees.

Molecular phylogenies of Charadriiformes based on mtDNA genes and one to three nuclear loci do not support the traditional placement of Pluvialis in the plovers (Charadriidae), assigning it instead to oystercatchers, stilts, and avocets (Haematopodidae and Recurvirostridae). To investigate this hypothesis of plover paraphyly, the relationships among Pluvialis and closely related families were revisited by sequencing two individuals of all taxa except Peltohyas for eight independent single copy nuclear protein-coding loci selected for their informativeness at this phylogenetic depth. The species tree estimated jointly with the gene trees in the coalescent programme (*)BEAST strongly supported plover monophyly, as did Bayesian analysis of the concatenated matrix.

D-scan measurement of nonlinear refractive index in fibers heavily doped with GeO2.

Concentration dependence of nonlinear refractive index n2 in fibers heavily doped with GeO2 is studied by using the D-scan method. Good agreement with an empirical dependence established earlier with lower GeO2 concentrations by the cw dual-frequency beat signal technique is shown for GeO2 concentrations up to approximately 100 mol.%.

The structure of optimal time- and age-dependent harvesting in the Lotka-McKendrik population model.

The paper analyzes optimal harvesting of age-structured populations described by the Lotka-McKendrik model. It is shown that the optimal time- and age-dependent harvesting control involves only one age at natural conditions. This result leads to a new optimization problem with the time-dependent harvesting age as an unknown control.

Optimization of harvesting age in an integral age-dependent model of population dynamics.

The paper deals with optimal control in a linear integral age-dependent model of population dynamics. A problem for maximizing the harvesting return on a finite time horizon is formulated and analyzed. The optimal controls are the harvesting age and the rate of population removal by harvesting.