Social behavior-induced multistability in minimal competitive ecosystems.

Mimimal models of coordinated behavior of populations living in the same environment are introduced for the cases when they either both gain by mutual interactions, or one hunts the other one, or finally when they compete with each other. The equilibria of the systems are analysed, showing that in some cases the populations may both disappear. Coexistence leads to global asymptotic stability for symbiotic populations, or to Hopf bifurcations for predator-prey systems. Finally, a new very interesting phenomenon is discovered in the competition case: tristability may be achieved showing that the principle of competitive exclusion fails in this case. Indeed either one of the competing populations may thrive, but also the case of populations coexistence is allowed, for the same set of parameter values.

Lung assist devices influence cardio-energetic parameters: Numerical simulation study.

We aim at an analysis of the effects mechanical ventilators (MVs) and thoracic artificial lungs (TALs) will have on the cardiovascular system, especially on important quantities, such as left and right ventricular external work (EW), pressure-volume area (PVA) and cardiac mechanical efficiency (CME). Our analyses are based on simulation studies which were carried out by using our CARDIOSIM(©) software simulator. At first, we carried out simulation studies of patients undergoing mechanical ventilation (MV) without a thoracic artificial lung (TAL). Subsequently, we conducted simulation studies of patients who had been provided with a TAL, but did not undergo MV. We aimed at describing the patient's physiological characteristics and their variations with time, such as EW, PVA, CME, cardiac output (CO) and mean pulmonary arterial/venous pressure (PAP/PVP). We were starting with a simulation run under well-defined initial conditions which was followed by simulation runs for a wide range of mean intrathoracic pressure settings. Our simulations of MV without TAL showed that for mean intrathoracic pressure settings from negative (-4 mmHg) to positive (+5 mmHg) values, the left and right ventricular EW and PVA, right ventricular CME and CO decreased, whereas left ventricular CME and the PAP increased. The simulation studies of patients with a TAL, comprised all the usual TAL arrangements, viz. configurations "in series" and in parallel with the natural lung and, moreover, hybrid configurations. The main objective of the simulation studies was, as before, the assessment of the hemodynamic response to the application of a TAL. We could for instance show that, in case of an "in series" configuration, a reduction (an increase) in left (right) ventricular EW and PVA values occurred, whereas the best performance in terms of CO can be achieved in the case of an in parallel configuration.

Ecoepidemics overcoming the species barrier and being subject to harvesting.

An ecoepidemiological model in which the disease can be transmitted from one population to another one is considered. Linear harvesting on all the populations is considered. By means of numerical simulations, the role of the epidemiological parameters as well as that of harvesting are investigated. Some relevant consequences of harvesting on the system dynamics are discovered.

Infantile digital fibromatosis: our experience and long-term results.

Infantile fibromatosis is an uncommon benign proliferation of myofibroblasts in the dermal tissue on the digits and toes with a marked tendency for recurrence. Inclusion bodies in the cytoplasm of neoplastic fibroblasts are a characteristic histologic feature of this condition. The tumor may often resolve spontaneously. There is very little written in the literature on this subject, with only a few or isolated cases having been described. We report our experience of seven cases of recurrent infantile fibromatosis that underwent surgical treatment.

[Mathematical model of invasion of mysids (Mysidacea) into the Naroch Lake system].

We present a mathematical model of the invasion of mysid into the Naroch Lake system. The model is parameterized with the use of field observation data. We show that the mysid invasion can lead to an increase in the time-averaged fish population size, and to a decrease in the time-averaged rotifer population size.

[Surgical treatment of gastrointestinal stromal tumors: personal cases]. / Trattamento chirurgico dei tumori stromali gastrointestinali: casistica personale.

Surgical management of gastrointestinal stromal tumors: our experience. Gastrointestinal stromal tumors (GIST) are rare neoplasm even if they are the most common mesenchimal malignancies of the gastrointestinal tract. GIST have long been a source of confusion and controversy, in particular to define their pathological classification, preoperative diagnosis, management strategies, and prognosis. A radical resection of the tumor is often possible and always recommended. Recent studies have identified its principal pathogenic defect. An effective adjuvant therapy treatment (STI571) have been found for advanced and metastatic GIST.

The effects of diseases on competing species.

In this paper we study the dynamics of two competing species when one of them is subject to a disease. In order to keep the model simple, we present it under the strong assumption that the disease cannot cross the species barrier. We answer several important questions about the long term behavior of the environment. In this situation, no population is necessarily wiped out. Also, not every individual of the infected species is bound to contract the disease. Finally, disease-induced persistent cycles for the populations are admissible.

Chaos and regular dynamics in model multi-habitat plankton-fish communities.

This work is focused on the role of diffusive interaction between separate habitats in a patchy environment in plankton pattern formation. We demonstrate that conceptual reaction-diffusion mathematical models constitute an appropriate tool for searching and understanding basic mechanisms of plankton pattern formation and complex spatio-temporal plankton dynamics

Lipomatous tumors of the uterus: ultrasonographic findings in 11 cases.

We reviewed the ultrasonographic findings in eight patients with 11 lipomatous uterine tumors studied with transabdominal (eight cases) and transvaginal (six cases) techniques. A transvaginal color Doppler study was obtained in five patients. Two patients had more than one nodule (two and three uterine nodules, respectively). All lipomatous tumors had regular margins and were hyperechoic. Transvaginal sonography allowed the identification of one small previously undetected tumor but was not able to image the entire extent of two large lipomatous masses. In one case, it helped to establish the actual uterine origin of an eccentric pelvic mass. Color Doppler sonography showed complete absence of flow in all tumors examined. We believe that lipomatous tumors of the uterus can be diagnosed with a high degree of certainty by ultrasonography if a homogeneously hyperechoic avascular mass can be clearly identified to be of uterine origin.