In this paper, we study the asymptotic dynamics of two chemostat models with random environmental fluctuations modeled by means of real noise, where different consumption functions for the consumer ...species (Monod and Haldane) are taking into account. For each model, our main goal is to investigate the existence of deterministic attracting sets. This allows us to provide conditions under which the species become extinct or persist, which is the main goal in industrial setup. In addition, we depict different numerical simulations to support the theoretical results. Finally, we present some conclusions to sum up our contribution and we compare how the species behave depending on its consumption function.
•How to model bounded random fluctuations in mathematical models of life sciences.•Providing useful information about the long-time behavior of the mathematical models.•Ensuring the persistence and ...coexistence of the species to be analyzed.
In this paper, we analyze the use of the Ornstein–Uhlenbeck process to model dynamical systems subjected to bounded noisy perturbations. In order to discuss the main characteristics of this new approach we consider some basic models in population dynamics such as the logistic equations and competitive Lotka–Volterra systems. The key is the fact that these perturbations can be ensured to keep inside some interval that can be previously fixed, for instance, by practitioners, even though the resulting model does not generate a random dynamical system. However, one can still analyze the forwards asymptotic behavior of these random differential systems. Moreover, to illustrate the advantages of this type of modeling, we exhibit an example testing the theoretical results with real data, and consequently one can see this method as a realistic one, which can be very useful and helpful for scientists.
Aim
The architecture of neonatal units plays a key role in developmental strategies and preterm outcomes. The aim was to evaluate the design of Spanish neonatal units and its impact on the ...participation of parents in neonatal care.
Methods
A web‐based survey was sent to all level III Spanish neonatal units, including questions about hospital data, architectural design, facilities and family participation.
Results
The study included 63 units. Most units (87%) had part or all the intensive care patients located in open bay units, while 54% had at least one individual patient cubicle. Single family rooms, defined as those including enough space and furniture for family members to stay with the infant without restrictions, were available in 8 units (13%). Eighteen units (29%) had a structured programme of family education. Units with single family rooms were more likely to have parental participation in rounds (p < 0.01), safety protocols (p = 0.02), oxygen management (p < 0.01) and nasogastric tube feeding (p = 0.02), as well as to allow siblings to participate in kangaroo care (p < 0.01).
Conclusion
Widely variable architectural designs and policies were found in Spanish neonatal units. The presence of single family rooms may have impacted the participation of parents in neonatal care.
In this paper, we analyze a chemostat model with wall growth where the input flow is perturbed by two different stochastic processes: the well-known standard Wiener process, which leads into several ...drawbacks from the biological point of view, and a suitable Ornstein-Uhlenbeck process depending on some parameters which allow us to control the noise to be bounded inside some interval that can be fixed previously by practitioners. Thanks to this last approach, which has already proved to be very realistic when modeling other simplest chemostat models, it will be possible to prove the persistence and coexistence of the species in the model without needing the theory of random dynamical systems and pullback attractors needed when dealing with the Wiener process. This is an advantage since the theoretical framework in this paper is much less complicated and provides us much more information than the other.
Non-autonomous chemostat models with non-monotonic growth Caraballo, Tomás; López-de-la-Cruz, Javier; Caraballo-Romero, Verónica
International journal of computer mathematics,
11/2022, Letnik:
ahead-of-print, Številka:
ahead-of-print
Journal Article
Recenzirano
In this paper, we investigate four non-autonomous chemostat models with non-monotonic consumption function, where wall growth and nutrient recycling are also taken into account. In each case, we ...prove the existence and uniqueness of non-negative global solution that generates a non-autonomous dynamical system. In addition, we also prove the existence of a unique (global) pullback attractor whose internal structure provides detailed information about the long-time behaviour of the state variables, for instance, conditions to ensure the extinction and the persistence of the species. We also display numerical simulations to illustrate the theoretical results.
Background
Tibial plateau fractures involving posteromedial (PM) and posterolateral (PL) columns are complex injuries that require an appropriate approach. The management of the PL column in these ...cases can be controversial, and limitations using deep posteromedial interval approaches have been referenced. In this paper, a modification of the Lobenhoffer approach, designed to optimize the access to the PL column, is described in detail. The aim of this study was to assess the feasibility of this approach in a cadaveric anatomical study.
Materials and methods
In total, five fresh-frozen cadaveric specimens were used for detailed anatomical study surrounding the approach. Relationships with cutaneous and deep neurovascular structures were evaluated. The exposure area of the PL and PM columns using this approach was assessed.
Results
The cadaveric study showed safe and adequate exposure. Oblique skin and fascia incision just medial to the posterior midline was safe to protect the medial sural cutaneous nerve and the small saphenous vein. Elevation of the popliteus and tibialis posterior muscles offered safe protection of the anterior tibial artery and popliteal neurovascular bundle during retractor placement. Adequate full proximal exposure of the PM and PL columns, including the posterolateral lateral (PLL) and posterolateral central (PLC) segments, was obtained in all specimens.
Conclusions
The Modified Oblique Lobenhoffer (MOL) approach can be a feasible option to access PL and PM columns in tibial plateau fractures.
Level of evidence
IV.
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