Analysis of a model for waterborne diseases with Allee effect on bacteria

A limitation of current modeling studies in waterborne diseases (one of the leading causes of death worldwide) is that the intrinsic dynamics of the pathogens is poorly addressed, leading to incomplete, and often, inadequate understanding of the pathogen evolution and its impact on disease transmission and spread. To overcome these limitations, in this paper, we consider an ODEs model with bacterial growth inducing Allee effect. We adopt an adequate functional response to significantly express the shape of indirect transmission. The existence and stability of biologically meaningful equilibria is investigated through a detailed discussion of both backward and Hopf bifurcations. The sensitivity analysis of the basic reproduction number is performed. Numerical simulations confirming the obtained results in two different scenarios are shown

Auditory cortex hypoperfusion: a metabolic hallmark in Beta Thalassemia

Abstract Background Sensorineural hearing loss in beta-thalassemia is common and it is generally associated with iron chelation therapy. However, data are scarce, especially on adult populations, and a possible involvement of the central auditory areas has not been investigated yet. We performed a multicenter cross-sectional audiological and single-center 3Tesla brain perfusion MRI study enrolling 77 transfusion-dependent/non transfusion-dependent adult patients and 56 healthy controls. Pure tone audiometry, demographics, clinical/laboratory and cognitive functioning data were recorded. Results Half of patients (52%) presented with high-frequency hearing deficit, with overt hypoacusia (Pure Tone Average (PTA) > 25 dB) in 35%, irrespective of iron chelation or clinical phenotype. Bilateral voxel clusters of significant relative hypoperfusion were found in the auditory cortex of beta-thalassemia patients, regardless of clinical phenotype. In controls and transfusion-dependent (but not in non-transfusion-dependent) patients, the relative auditory cortex perfusion values increased linearly with age (p < 0.04). Relative auditory cortex perfusion values showed a significant U-shaped correlation with PTA values among hearing loss patients, and a linear correlation with the full scale intelligence quotient (right side p = 0.01, left side p = 0.02) with its domain related to communication skills (right side p = 0.04, left side p = 0.07) in controls but not in beta-thalassemia patients. Audiometric test results did not correlate to cognitive test scores in any subgroup. Conclusions In conclusion, primary auditory cortex perfusion changes are a metabolic hallmark of adult beta-thalassemia, thus suggesting complex remodeling of the hearing function, that occurs regardless of chelation therapy and before clinically manifest hearing loss. The cognitive impact of perfusion changes is intriguing but requires further investigations

Turing patterns in a reaction–diffusion system modeling hunting cooperation

A reaction–diffusion system governing the prey–predator interaction with hunting cooperation is investigated. Definitive boundedness of solutions is proved via the existence of positive invariants and attractive sets. Linear stability of the coexistence equilibria is performed and conditions guaranteeing the occurrence of Turing instability are found. Numerical simulations on the obtained results are provided

Hearing Loss in Beta-Thalassemia: Systematic Review

In the last half century, the life expectancy of beta-thalassemia patients has strikingly increased mostly due to regular blood transfusions and chelation treatments. The improved survival, however, has allowed for the emergence of comorbidities, such as hearing loss, with a non-negligible impact on the patients&rsquo; quality of life. This thorough review analyzes the acquired knowledge regarding hearing impairment in this hereditary hemoglobinopathy, aiming at defining its prevalence, features, course, and possible disease- or treatment-related pathogenic factors. Following PRISMA criteria, we retrieved 60 studies published between 1979 and 2021. Diagnostic tools and criteria, forms of hearing impairment, correlations with beta-thalassemia phenotypes, age and sex, chelation treatment and laboratory findings including iron overload, were carefully searched, analyzed and summarized. In spite of the relatively high number of studies in the last 40 years, our knowledge is rather limited, and large prospective studies with homogeneous diagnostic tools and criteria are required to define all the aforementioned issues. According to the literature, the overall prevalence rate of hearing impairment is 32.3%; age, sex, and laboratory findings do not seem to correlate with hearing deficits, while the weak relationship with clinical phenotype and chelation treatment seems to highlight the presence of further yet to be identified pathogenic factors

New results on protons inside the South Atlantic Anomaly, at energies between 40-250 MeV in the period 2018-2020, from the CSES-01 satellite mission

The High-Energy Particle Detector (HEPD) on board the China Seismo-Electromagnetic Satellite (CSES-01) was launched in February 2018, with a foreseen mission lifetime of over 5 years. It is providing crucial new insight in the physical dynamics of the radiation belts in the Earth's magnetosphere, in particular in the South Atlantic Anomaly (SAA). In this work, proton data from HEPD in the 40 MeV-250 MeV energy range, collected inside the SAA during the period between August 2018 and December 2020, are presented and compared with the up-to-date AP9 model by NASA. These are the first results on SAA protons at Low-Earth Orbit during the minimum activity phase between the 24th and the 25th solar cycles below 250 MeV. They enable an extensive testing and validation of current theoretical and empirical models aimed at predictions of temporal changes in this critical region of space. HEPD is advancing the observations collected by the PAMELA space experiment and NASA Van Allen Probe during the last 15 years through the 23rd and 24th solar cycles

The HEPD particle detector of the CSES satellite mission for investigating seismo-associated perturbations of the Van Allen belts

CSES (China Seismo-Electromagnetic Satellite) is a mission developed by CNSA (Chinese National Space Administration) and ASI (Italian Space Agency), to investigate the near-Earth electromagnetic, plasma and particle environment, for studying the seismo-associated disturbances in the ionosphere-magnetosphere transition zone. The anthropogenic and electromagnetic noise, as well as the natural non-seismic electromagnetic emissions is mainly due to tropospheric activity. In particular, the mission aims to confirming the existence of possible temporal correlations between the occurrence of earthquakes for medium and strong magnitude and the observation in space of electromagnetic perturbations, plasma variations and precipitation of bursts with high-energy charged particles from the inner Van Allen belt. In this framework, the high energy particle detector (HEPD) of the CSES mission has been developed by the Italian LIMADOU Collaboration. HEPD is an advanced detector based on a tower of scintillators and a silicon tracker that provides good energy and angular resolution and a wide angular acceptance, for electrons of 3–100 MeV, protons of 30–200 MeV and light nuclei up to the oxygen. CSES satellite has been launched on February 2nd, 2018 from the Jiuquan Satellite Launch Center (China). © 2018, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature