Period-doubling cascade to chaos and optimal quadratic harvesting in a prey-predator-scavenger model using Crowley-Martin functional response.

In the present article, a prey-predator-scavenger model is proposed and investigated with quadratic harvesting of predator and scavenger populations. The system is assumed to follow the Crowley-Martin functional response to describe the interaction between prey and predator populations. The positivity and boundedness of the system with respect to positive initial conditions are established.

Predator-prey dynamics with refuge, alternate food, and harvesting strategies in a patchy habitat.

A predator-prey dynamic reaction model is investigated in a two-layered water body where only the prey is subjected to harvesting. The surface layer (Layer-1) provides food for both species, while the prey migrates to deeper layer (Layer-2) as a refuge from predation. Although the prey is the preferred food for the predator, the predator can also consume alternative food resources that are abundantly available.

Increase maximum economic yield in a patchy environment.

In this work, we study the model of a fish species growing logistically exploited by a fishing fleet in a heterogeneous environment. The environment is made up of a network of fishing patches connected by fish migrations taking place on a fast time scale. We are interested in the maximum economic yield (MEY) which corresponds to the maximum profit made by the fishing fleet.

The impact of immune cell interactions on virus quasi-species formation.

The process of viral infection spreading in tissues was influenced by various factors, including virus replication within host cells, transportation, and the immune response. Reaction-diffusion systems provided a suitable framework for examining this process. In this work, we studied a nonlocal reaction-diffusion system of equations that modeled the distribution of viruses based on their genotypes and their interaction with the immune response.

Sustainable management of predatory fish affected by an Allee effect through marine protected areas and taxation.

Ecological balance and stable economic development are crucial for the fishery. This study proposes a predator-prey system for marine communities, where the growth of predators follows the Allee effect and takes into account the rapid fluctuations in resource prices caused by supply and demand. The system predicts the existence of catastrophic equilibrium, which may lead to the extinction of prey, consequently leading to the extinction of predators, but fishing efforts remain high.

On the date of the epidemic peak.

Epidemiologists have used the timing of the peak of an epidemic to guide public health interventions. By determining the expected peak time, they can allocate resources effectively and implement measures such as quarantine, vaccination, and treatment at the right time to mitigate the spread of the disease. The peak time also provides valuable information for those modeling the spread of the epidemic and making predictions about its future trajectory.

On a two-strain epidemic model involving delay equations.

We propose an epidemiological model for the interaction of either two viruses or viral strains with cross-immunity, where the individuals infected by the first virus cannot be infected by the second one, and without cross-immunity, where a secondary infection can occur. The model incorporates distributed recovery and death rates and consists of integro-differential equations governing the dynamics of susceptible, infectious, recovered, and dead compartments. Assuming that the recovery and death rates are uniformly distributed in time throughout the duration of the diseases, we can simplify the model to a conventional ordinary differential equation (ODE) model.

The influence of immune cells on the existence of virus quasi-species.

This article investigate a nonlocal reaction-diffusion system of equations modeling virus distribution with respect to their genotypes in the interaction with the immune response. This study demonstrates the existence of pulse solutions corresponding to virus quasi-species. The proof is based on the Leray-Schauder method, which relies on the topological degree for elliptic operators in unbounded domains and a priori estimates of solutions.

Nonlinear diffusion in multi-patch logistic model.

We examine a multi-patch model of a population connected by nonlinear asymmetrical migration, where the population grows logistically on each patch. Utilizing the theory of cooperative differential systems, we prove the global stability of the model. In cases of perfect mixing, where migration rates approach infinity, the total population follows a logistic law with a carrying capacity that is distinct from the sum of carrying capacities and is influenced by migration terms.

A model of a fishery with fish storage and variable price involving delay equations.

We propose a bio-economic model of a fishery describing the variations of the fish stock, the fishing effort and the price of the resource on the market supposed to depend on supply and demand. The originality of this model comes from taking into account the storage of part of the resource for a certain time before being put up for sale on the market. Taking into account the supposedly fast price dynamics compared to the other mechanisms involved and after integration of the stock equation, the system is reduced to a system of two delayed differential equations.

On the Threshold of Release of Confinement in an Epidemic SEIR Model Taking into Account the Protective Effect of Mask.

We present a classic SEIR model taking into account the daily movements of individuals in different places. The model also takes into account partial confinement of individuals. This model is coupled with a model of protection against the epidemic by the use of masks.

Transmission dynamics of COVID-19 in Algeria: The impact of physical distancing and face masks.

We propose an SIR epidemic model taking into account prevention measures against coronavirus disease 2019 (COVID-19) such as wearing masks and respecting safety distances. We look for the conditions to avoid a second epidemic peak in the phase of release from confinement. We derive equations for the critical levels of mask efficiency, mask adoption (fraction of population wearing masks) and fraction of population engaging in physical distancing that lower the basic reproduction number to unity.

HER-2 status of circulating tumor cells in a metastatic breast cancer cohort: A comparative study on characterization techniques.

Background: Personalized targeted treatment in metastatic breast cancer relies on accurate assessment of molecular aberrations, e.g. overexpression of Human Epidermal growth factor Receptor 2 (HER-2).

Modeling the imported malaria to north Africa and the absorption effect of the immigrants.

As Malaria represents one of the major health burdens in Africa, there is a risk of reappearance of this vector-borne disease in malaria-free or low risk countries such as those in North Africa. One of the factors that can lead to this situation is the flow of sub-Saharan immigrants trying to reach Europe through North Africa. In this work, we investigate such a possibility via a mathematical model.

Effect of hawk-dove game on the dynamics of two competing species.

Outcomes of interspecific competition, and especially the possibility of coexistence, have been extensively studied in theoretical ecology because of their implications in community assemblages. During the last decades, the influence of different time scales through the local/regional dynamics of animal communities has received an increasing attention. Nevertheless, different time scales involved in interspecific competition can result form other processes than spatial dynamics.

Basic reproduction ratio for a fishery model in a patchy environment.

We present a dynamical model of a multi-site fishery. The fish stock is located on a discrete set of fish habitats where it is catched by the fishing fleet. We assume that fishes remain on fishing habitats while the fishing vessels can move at a fast time scale to visit the different fishing sites.

Optimal number of sites in multi-site fisheries with fish stock dependent migrations.

We present a stock-effort dynamical model of a fishery subdivided into fishing zones. The stock corresponds to a fish population moving between these zones, on which they are harvested by fishing fleets. We consider a linear chain of identical fishing zones.

[Retroperitoneal laparoscopic treatment of parapelvic renal cysts: report of 5 cases].

Objectives: Renal cysts of the sinuses or parapelvic cysts constitute a rare form of renal cyst, usually associated with low back pain. Symptomatic forms may be treated by percutaneous aspiration, but the treatment of these cysts has changed considerably over recent years due to the proximity of the renal hilum. Percutaneous treatment is now contraindicated due to its high complication rate, and open surgery is an invasive technique.

[Inflammatory myofibroblastic tumours of the bladder].

The inflammatory myofibroblastic tumour of the bladder is a rare benign affection that interests mainly young adults. Its etiopathogeny remains unknown, but its tumoral origin was evocated recently by Griffin (1999), incriminating a chromosomic abnormality involving the ALK gene. We will discuss the etiopathogenic, anatopathological and therapeutical aspects of this lesion for which the diagnosis is histological and the treatment remains conservative with a good prognosis.

[Congenital male urethral diverticulum].

The male urethral diverticulum is a rare affection. The authors report one case of congenital urethral diverticulum. The diagnosis was approved by clinical examination and urethrocystography.