General Allee Effect in Two-Species Population Biology

The main objective of this work is to present a general framework for the notion of the strong Allee effect in population models, including competition, mutualistic, and predator–prey models. The study is restricted to the strong Allee effect caused by an inter-specific interaction. The main feature of the strong Allee effect is that the extinction equilibrium is an attractor. We show how a ‘phase space core’ of three or four equilibria is sufficient to describe the essential dynamics of the interaction between two species that are prone to the Allee effect. We will introduce the notion of semistability in planar systems. Finally, we show how the presence of semistable equilibria increases the number of possible Allee effect cores

A Continuous-Time Mathematical Model and Discrete Approximations for the Aggregation of \u3cem\u3eβ\u3c/em\u3e-Amyloid

Alzheimer\u27s disease is a degenerative disorder characterized by the loss of synapses and neurons from the brain, as well as the accumulation of amyloid-based neuritic plaques. While it remains a matter of contention whether β-amyloid causes the neurodegeneration, β-amyloid aggregation is associated with the disease progression. Therefore, gaining a clearer understanding of this aggregation may help to better understand the disease. We develop a continuous-time model for β-amyloid aggregation using concepts from chemical kinetics and population dynamics. We show the model conserves mass and establish conditions for the existence and stability of equilibria. We also develop two discrete-time approximations to the model that are dynamically consistent. We show numerically that the continuous-time model produces sigmoidal growth, while the discrete-time approximations may exhibit oscillatory dynamics. Finally, sensitivity analysis reveals that aggregate concentration is most sensitive to parameters involved in monomer production and nucleation, suggesting the need for good estimates of such parameters

Do Open Access Dental Articles Enjoy Higher Altmetric Attention Scores, Twitter, Facebook, News, Wikipedia, Blog mentions, Mendeley Readers and Citations?

In order to access articles published in conventional (non-open access) journals, scientists must utilize tools such as subscriptions, site licenses or pay-per-view charges. In contrast, open access articles can be accessed without financial, legal or technical barriers. A large-scale study estimated that at least 28% of the academic literature is open access (19 million in total) and that this percentage is growing.[1] A recent survey showed an open access rate in field of dentistry at 45.8%.[2] It has been demonstrated that open access articles had 8% to 40% higher citations compared to non-open access articles; this has been termed, “open access citation advantage”.[3],[4],[5

Cross-Cultural Adaptations of the MacArthur Competence Assessment Tool for Treatment in Iran

Background: According to general ethical and legal principles, valid consent must be obtained before starting any procedure. Objectives: Due to the lack of a standard tool for assessing patients’ capacity to consent to medical treatment in Iran, the present study was carried out aiming to devise a Persian version of a cross-cultural adaptation of the MacArthur competence assessment tool. Patients and Methods: By reviewing different methods of cultural translation and adaptation for assessment tools, and due to the lack of consensus on its processes, we selected Wild’s model as one of the most comprehensive methods in this regard. Wild’s (2005) 10-stage model includes preparation, forward translation, reconciliation of the forward translation, back translation of reconciliation, back translation review, cognitive debriefing and cognitive review, and finalization, proofreading and final reporting. Using this model, we translated the MacArthur assessment tool and made it adaptable to Iranian patients. Results: The MacArthur assessment tool is not dependent on any specific culture and language. As a result, if translation and its scientific adaptation are done based on an integrated and detailed model, the tool can be used for every culture and language. In other words, this tool is not culture-specific; so, it is applicable in cases where a translation is needed, and it can be culturally adapted to suit different societies. Conclusions: In the present study, we are able to focus on and prove the efficacy and benefits of this measurement tool

Identification and Energy Measurements of Light Particles with a CsI(Tl)-Photodiode Combination

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Pleiotropic Effects of Tetracyclines in the Management of COVID-19: Emerging Perspectives

Coronavirus disease 2019 (COVID-19) is a global infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Approximately 15% of severe cases require an intensive care unit (ICU) admission and mechanical ventilation due to development of acute respiratory distress syndrome (ARDS). Tetracyclines (TCs) are a group of bacteriostatic antibiotics, like tetracycline, minocycline, and doxycycline, effective against aerobic and anaerobic bacteria as well as Gram-positive and Gram-negative bacteria. Based on available evidences, TCs may be effective against coronaviruses and thus useful to treat COVID-19. Thus, this review aims to provide a brief overview on the uses of TCs for COVID-19 management. SARS-CoV-2 and other coronaviruses depend mainly on the matrix metalloproteinases (MMPs) for their proliferation, cell adhesion, and infiltration. The anti-inflammatory mechanisms of TCs are linked to different pathways. Briefly, TCs inhibit mitochondrial cytochrome c and caspase pathway with improvement of lymphopenia in early COVID-19. Specifically, minocycline is effective in reducing COVID-19–related complications, through attenuation of cytokine storm as apparent by reduction of interleukin (IL)-6, IL-1, and tumor necrosis factor (TNF)-a. Different clinical trials recommend the replacement of azithromycin by minocycline in the management of COVID-19 patients at high risk due to two main reasons: 1) minocycline does not prolong the QT interval and even inhibits ischemia-induced arrhythmia; 2) minocycline displays synergistic effect with chloroquine against SARS-CoV-2. Taken together, the data presented here show that TCs, mainly doxycycline or minocycline, may be potential partners in COVID-19 management, derived pneumonia, and related complications, such as acute lung injury (ALI) and ARDS.The authors thank all members of the College of Medicine, Al-Mustansiyria University. NC-M acknowledges the Portuguese Foundation for Science and Technology under the Horizon 2020 Program (PTDC/PSI-GER/28076/2017)

Phase transitions of a spin-one Ising ferromagnetic superlattice

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Fault-Tolerant Aggregation: Flow-Updating Meets Mass-Distribution

Flow-Updating (FU) is a fault-tolerant technique that has proved to be efficient in practice for the distributed computation of aggregate functions in communication networks where individual processors do not have access to global information. Previous distributed aggregation protocols, based on repeated sharing of input values (or mass) among processors, sometimes called Mass-Distribution (MD) protocols, are not resilient to communication failures (or message loss) because such failures yield a loss of mass. In this paper, we present a protocol which we call Mass-Distribution with Flow-Updating (MDFU). We obtain MDFU by applying FU techniques to classic MD. We analyze the convergence time of MDFU showing that stochastic message loss produces low overhead. This is the first convergence proof of an FU-based algorithm. We evaluate MDFU experimentally, comparing it with previous MD and FU protocols, and verifying the behavior predicted by the analysis. Finally, given that MDFU incurs a fixed deviation proportional to the message-loss rate, we adjust the accuracy of MDFU heuristically in a new protocol called MDFU with Linear Prediction (MDFU-LP). The evaluation shows that both MDFU and MDFU-LP behave very well in practice, even under high rates of message loss and even changing the input values dynamically.Comment: 18 pages, 5 figures, To appear in OPODIS 201