Stability of coupled Wilson-Cowan systems with distributed delays

Building upon our previous work on the Wilson-Cowan equations with distributed delays, we study the dynamic behavior in a system of two coupled Wilson-Cowan pairs. We focus in particular on understanding the mechanisms that govern the transitions in and out of oscillatory regimes associated with pathological behavior. We investigate these mechanisms under multiple coupling scenarios, and we compare the effects of using discrete delays versus a weak Gamma delay distribution. We found that, in order to trigger and stop oscillations, each kernel emphasizes different critical combinations of coupling weights and time delay, with the weak Gamma kernel restricting oscillations to a tighter locus of coupling strengths, and to a limited range of time delays. We finally illustrate the general analytical results with simulations for two particular applications: generation of beta-rhytms in the basal ganglia, and alpha oscillations in the prefrontal-limbic system

Al maestro con cariño

Cuando pensamos en un maestro nos imaginamos un sinfín de espacios educativos en los que su presencia se hace sentir. La calle, la facultad, el barrio, los medios de comunicación, las reuniones de la militancia, la vida en familia. Y lo asociamos a un modo de educar donde los temas, los enfoques, las palabras, los gestos, las intensidades e intenciones tienen un gran poder de interpelarnos como seres humanos. Para un grupo de compañeros de militancias varias, Jorge ha sido la puerta de entrada a conceptos, a miradas de profundo sentido liberador

Colonic content in health and its relation to functional gut symptoms

This is the peer reviewed version of the following article: Bendezú, R. A., Barba, E., Burri, E., Cisternas, D., Accarino, A., Quiroga, S., Monclus, E., Navazo, I., Malagelada, J.-R. and Azpiroz, F. (2016), Colonic content in health and its relation to functional gut symptoms. Neurogastroenterol. Motil., 28: 849–854, which has been published in final form at [doi:10.1111/nmo.12782]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingGut content may be determinant in the generation of digestive symptoms, particularly in patients with impaired gut function and hypersensitivity. Since the relation of intraluminal gas to symptoms is only partial, we hypothesized that non-gaseous component may play a decisive role. Methods: Abdominal computed tomography scans were evaluated in healthy subjects during fasting and after a meal (n = 15) and in patients with functional gut disorders during basal conditions (when they were feeling well) and during an episode of abdominal distension (n = 15). Colonic content and distribution were measured by an original analysis program. Key results: In healthy subjects both gaseous (87 ± 24 mL) and non-gaseous colonic content (714 ± 34 mL) were uniformly distributed along the colon. In the early postprandial period gas volume increased (by 46 ± 23 mL), but non-gaseous content did not, although a partial caudad displacement from the descending to the pelvic colon was observed. No differences in colonic content were detected between patients and healthy subjects. Symptoms were associated with discrete increments in gas volume. However, no consistent differences in non-gaseous content were detected in patients between asymptomatic periods and during episodes of abdominal distension. Conclusions & inferences: In patients with functional gut disorders, abdominal distension is not related to changes in non-gaseous colonic content. Hence, other factors, such as intestinal hypersensitivity and poor tolerance of small increases in luminal gas may be involved.Peer ReviewedPostprint (author's final draft

Opioid Injection-Associated Bacterial Infections in England, 2002–2021: A Time Series Analysis of Seasonal Variation and the Impact of Coronavirus Disease 2019

BACKGROUND: Bacterial infections cause substantial pain and disability among people who inject drugs. We described time trends in hospital admissions for injecting-related infections in England. METHODS: We analyzed hospital admissions in England between January 2002 and December 2021. We included patients with infections commonly caused by drug injection, including cutaneous abscesses, cellulitis, endocarditis, or osteomyelitis, and a diagnosis of opioid use disorder. We used Poisson regression to estimate seasonal variation and changes associated with coronavirus disease 2019 (COVID-19) response. RESULTS: There were 92 303 hospital admissions for injection-associated infections between 2002 and 2021. Eighty-seven percent were skin, soft-tissue, or vascular infections; 72% of patients were male; and the median age increased from 31 years in 2002 to 42 years in 2021. The rate of admissions reduced from 13.97 per day (95% confidence interval [CI], 13.59-14.36) in 2003 to 8.94 (95% CI, 8.64-9.25) in 2011, then increased to 18.91 (95% CI, 18.46-19.36) in 2019. At the introduction of COVID-19 response in March 2020, the rate of injection-associated infections reduced by 35.3% (95% CI, 32.1-38.4). Injection-associated infections were also seasonal; the rate was 1.21 (95% CI, 1.18-1.24) times higher in July than in February. CONCLUSIONS: This incidence of opioid injection-associated infections varies within years and reduced following COVID-19 response measures. This suggests that social and structural factors such as housing and the degree of social mixing may contribute to the risk of infection, supporting investment in improved social conditions for this population as a means to reduce the burden of injecting-related infections

Evaluation of the production of exopolysaccharides by two strains of the thermophilic bacterium Rhodothermus marinus

AbstractThe thermophile Rhodothermus marinus produces extracellular polysaccharides (EPSs) that forms a distinct cellular capsule. Here, the first data on EPS production in strains DSM4252T and MAT493 are reported and compared. Cultures of both strains, supplemented with either glucose, sucrose, lactose or maltose showed that the EPS were produced both in the exponential and stationary growth phase and that production in the exponential phase was boosted by maltose supplementation, while stationary phase production was boosted by lactose. The latter was higher, resulting in 8.8 (DSM4252T) and 13.7mg EPS/g cell dry weight (MAT493) in cultures in marine broth supplemented with 10g/L lactose. The EPSs were heteropolymeric with an average molecular weight of 8×104Da and different monosaccharides, including arabinose and xylose. FT-IR spectroscopy revealed presence of hydroxyl, carboxyl, N-acetyl, amine, and sulfate ester groups, showing that R. marinus produces unusual sulfated EPS with high arabinose and xylose content

Mathematical Modeling of the Transmission Dynamics of Ebola Virus Disease with control Strategies

In this paper we develop a deterministic compartmental mathematical model for the spread of the Ebola virus disease (EVD) in the community. Our model incorporates education campaigns, quarantine, safe burial and therapeutic treatment as control strategies to bring the disease to an end. We derived the effective reproductive number for the model, and proved the stability of equilibrium points. We performed numerical simulations of the model and our results show that all control measures under consideration have an effect of decreasing severity of the epidemic when constantly administered. Furthermore, we found that reducing the number of contacts with infectious individuals in the general population is the most effective intervention method for mitigating an EVD epidemic