Synchronization scenarios induced by delayed communication in arrays of diffusively coupled autonomous chemical oscillators.

We study the impact of delayed feedbacks in the collective synchronization of ensembles of identical and autonomous micro-oscillators. To this aim, we consider linear arrays of Belousov-Zhabotinsky (BZ) oscillators confined in micro-compartmentalised systems, where the delayed feedback mimics natural lags that can arise due to the confinement properties and mechanisms driving the inter-oscillator communication. The micro-oscillator array is modeled as a set of Oregonator-like kinetics coupled via mass exchange of the chemical messengers. Changes in the synchronization patterns are explored by varying the delayed feedback introduced in the messenger species Br2. A direct transition from anti-phase to in-phase synchronization and back to the initial anti-phase scheme is observed by progressively increasing the time delay from zero to the value T0, which is the oscillation period characterising the system without any delayed coupling. The route from anti- to in-phase oscillations (and back) consists of regimes where windows of in-phase oscillations are periodically broken by anti-phase beats. Similarities between these phase transition dynamics and synchronization scenarios characterising the coordination of oscillatory limb movements are finally discussed.

The Usage of an Air Purifier Device with HEPA 14 Filter during Dental Procedures in COVID-19 Pandemic: A Randomized Clinical Trial.

The aim of the present study was to evaluate the efficacy of an air purifier device (professional XXl inn-561 innoliving) with HEPA 14 filter in reducing the number of suspended particles generated during dental procedures as a vector of COVID-19 transmission. The survey was conducted on 80 individuals who underwent Oral Surgery with dental Hygiene Procedures, divided into two groups based on the operational risk classification related to dental procedures: a Test Group (with application of filtering device) and a Control Group (without filtering device). All procedures were monitored throughout the clinical controls, utilising professional tools such as molecular particle counters (Lasair III 350 L 9.50 L/min), bacteriological plates (Tryptic Soy Agar), sound meters for LAFp sound pressure level (SPL) and LCpk instantaneous peak level. The rate of suspended particles, microbiological pollution and noise pollution were calculated. SPSS software was used for statistical analysis method. The results showed the higher efficacy of the TEST Group on pollution abatement, 83% more than the Control fgroup. Additionally, the contamination was reduced by 69-80%. Noise pollution was not noticeable compared to the sounds already present in the clinical environment. The addition of PAC equipment to the already existing safety measures was found to be significantly effective in further microbiological risk reduction.

Bowel Perforation in Covid-19 Case Series.

OBJECTIVE: To describe the clinical characteristics and outcomes of patients with coronavirus disease 2019(COVID-19) who developed bowel perforation. MATERIALS AND METHODS: This case series was conducted in Emergency Department of AORN Sant'Anna and S. Sebastiano located in Caserta. All patients resulted positive to SARS-Cov-2 in nasopharyngeal swabs whith a positive laboratory test for SARS-CoV-2 from real time reverse transcription polymerase chain reaction(RT-PCR) as well as bowel perforation which was identified by abdominal CT, from September 2020 to December 2020. RESULTS: A total of five patients were identified with Bowel perforation occurred despite all patients being on anticoagulation. All patients were Italian, predominantly male(four patients) with an average age of 60 years and the most common comorbidity was hypertension, diabetes and obesity. DISCUSSION: Bowel perforation in COVID-19 is clinically significant with high morbidity and mortality. In our series 40% of patients who were diagnosed of bowel perforation died. Average time to death after bowel perforation diagnosis was 6 days. CONCLUSION: We describe a case series of COVID-19 patients who developed bowel perforation. KEY WORDS: Covid-19, Bowel perforation.

Dynamical model for sympatric speciation in an ecological niche.

The speciation phenomenon is the process used by the evolution to allow populations to become distinct species. The speciation is the primary cause of the complexity of the ecological network. Sympatric speciation concerns the rise of a new species from a surviving ancestral species while both continue to inhabit the same ecological niche or geographical region. In sympatric speciation, reproductive isolation evolves within a population in an ecological niche without the aid of geographic barriers. Different models have been proposed for alternative modes of sympatric speciation. The most popular was first put forward by John Maynard Smith in 1966 who suggested that in a given population homozygous individuals may, under particular environmental conditions, have a greater fitness than those with alleles heterozygous for a certain trait, eventually leading to speciation in the population. In this framework we assume an effective description of the speciation process based on a dynamical model for the populations in an ecological system. Our basic assumption is the existence of an ancestral population in an ecological niche that can express two phenotypes. In presence of certain environmental conditions one of the phenotypes has the propensity to separate from the original population in the reproduction process. Then new individuals may give rise to a new species in the ecosystem realizing a sympatric speciation. Due to the finite resources in the niche the populations are continuously competing each other's, and their numerousness fluctuates according to the changes of the environmental conditions. The effect of natural selection is introduced in the model by stochastic perturbations, that decrease the reproduction rate of the populations in the niche. We show some the dynamical properties of the system and we prove the existence of a threshold values in the environmental stress in order to observe the speciation process. We also discuss some biological implications of the model and the validation problem using empirical data.

[Treatment of splenic trauma in paediatric age]. / Trattamento del trauma splenico in età pediatrica vs età adulta. Nostra esperienza.

The splenic trauma in children presents some peculiarity that differentiates it from that one in adult age. Therefore we have see again our relative experience on splenic trauma, in the period 2001-2006, confronting two groups of patients, one of inferior age to fourteen years (A Group) and one of advanced age (B Group). We have estimated the following parameters: aetiology, type of lesion, association with others trauma, type of treatment, compliance, mortality, number of transfusions and hospital stay. On a total of 75 splenic trauma (M:52, F:23 of age comprised between 5 and 71 years) 18 belongs to the A group (medium age of 9.2 years) and 57 to the B group (medium ages of 47.4 years). The prevailing aetiology in the A group is domestic accident (39%) and the fall from bicycle (33%), while in the B group it is the street accident (69%). The lesions found in pediatric age are of smaller gravity if compared with B group, for lesion gravity and for association with abdominal and/or extra-abdominal others trauma. In the children group we have performed nonoperative management or conservative surgery in the 83% of cases versus the 26% in the B group. The rate of conversion from a nonoperative treatment in to an operative treatment has been of 7%. The post-operative complicance are absent in the A group and of 5.5% in the B group. The mortality rate in the surgical patients has been of the 14.3% for serious toraco-abdominal trauma in A group and of 11.1% in B group. No mortality is detected in the groups with nonoperative treatment. The medium number of transfusions is of 1.8 units in the paediatric patients and of 2.5 units in the adults. The medium stay in hospital is of eighteen days in the A group and of thirteen days in the B group. In conclusion the marked difference in the two groups examines stays in the type of treatment, more often nonoperative or conservative in the children group.

Numerical solution of a diffusion problem by exponentially fitted finite difference methods.

This paper is focused on the accurate and efficient solution of partial differential differential equations modelling a diffusion problem by means of exponentially fitted finite difference numerical methods. After constructing and analysing special purpose finite differences for the approximation of second order partial derivatives, we employed them in the numerical solution of a diffusion equation with mixed boundary conditions. Numerical experiments reveal that a special purpose integration, both in space and in time, is more accurate and efficient than that gained by employing a general purpose solver.