Dynamics and bifurcations in a simple quasispecies model of tumorigenesis

Cancer is a complex disease and thus is complicated to model. However, simple models that describe the main processes involved in tumoral dynamics, e.g., competition and mutation, can give us clues about cancer behaviour, at least qualitatively, also allowing us to make predictions. Here we analyze a simplified quasispecies mathematical model given by differential equations describing the time behaviour of tumor cells populations with different levels of genomic instability. We find the equilibrium points, also characterizing their stability and bifurcations focusing on replication and mutation rates. We identify a transcritical bifurcation at increasing mutation rates of the tumor cells population. Such a bifurcation involves an scenario with dominance of healthy cells and impairment of tumor populations. Finally, we characterize the transient times for this scenario, showing that a slight increase beyond the critical mutation rate may be enough to have a fast response towards the desired state (i.e., low tumor populations) during directed mutagenic therapies

Flash suppression and flash facilitation in binocular rivalry

We show that previewing one half image of a binocular rivalry pair can cause it to gain initial dominance when the other half is added, a novel phenomenon we term flash facilitation. This is the converse of a known effect called flash suppression, where the previewed image becomes suppressed upon rivalrous presentation. The exact effect of previewing an image depends on both the duration and the contrast of the prior stimulus. Brief, low-contrast prior stimuli facilitate, whereas long, high-contrast ones suppress. These effects have both an eye-based component and a pattern-based component. Our results suggest that, instead of reflecting two unrelated mechanisms, both facilitation and suppression are manifestations of a single process that occurs progressively during presentation of the prior stimulus. The distinction between the two phenomena would then lie in the extent to which the process has developed during prior stimulation. This view is consistent with a neural model previously proposed to account for perceptual stabilization of ambiguous stimuli, suggesting a relation between perceptual stabilization and the present phenomena

How do incumbent firms innovate their business models for the circular economy? Identifying micro‐foundations of dynamic capabilities

The circular economy is promoted as a contributor to sustainable development; however, the process of circular business model innovation remains under-explored to date, hindering its implementation. Dynamic capabilities research provides a theoretical perspective to explore how incumbent firms can innovate in rapidly changing environments. An abductive qualitative research is done through an exploratory multiple case study on 10 incumbents that implemented a circular business model innovation. We identify 26 practices, aggregated in 12 micro-foundations of the dynamic capabilities of sensing, seizing, and reconfiguring. By integrating the few empirical studies characterizing dynamic capabilities for sustainability-oriented business model innovation, we offer a comprehensive framework of 33 practices. This study proposes that the most relevant practices for circular business model innovation processes are adopting a lifecycle perspective, employing sustainability-oriented instruments, ideating sustainable value propositions, developing a sustainability strategy and culture, and engaging and coordinating stakeholders in the business ecosystem. We also suggest seven particularly relevant practices for long-term business model transformations (e.g., top management commitment), four for innovations focused on short and medium loops of the circular economy (e.g., early customer engagement), and four for long loops (e.g., business ecosystem coordination). This study corroborates and expands recent research on dynamic capabilities for sustainability-oriented innovation and provides practitioners with a set of 33 skills, processes, procedures, and activities to be prioritized to successfully innovate their business models for the circular economy

IR upgrade with quadrupoles first and dipoles first

We review recent work on the LHC IR upgrades by the US-LARP collaboration. There are several optics designs under consideration – each design differs in the potential luminosity reach, accelerator physics, operational and technical challenges etc. Here we consider two main issues: (i) the likely benefits of moving the IR magnets closer to the IP for both quadrupole first and dipole first designs and (ii) the impact of beam-beam interactions in the two designs. We conclude with a summary of accelerator physics parameters for the two designs

Iterated Nonlinear Control of Ship's Manoeuvring Models

This paper addresses the control design for a nonlinear vessel manoeuvring model. The authors consider a highly nonlinear vessel 4 DOF model. The proposed control algorithm consists of a combination of an iteration technique that approximates the original nonlinear model by a sequence of linear time varying (LTV) equations whose solution converge to the solution of the original nonlinear problem and, a lead compensation design in which for each of the iterated linear time varying systems, the controller is optimized at each time on the interval. The control designed for the last iteration is then applied to the original nonlinear problem. Simulations results show good performance of this approximation methodology and accurate tracking for certain manoeuvring cases under the control of the designed lead controller. The main characteristic of the nonlinear system's response are the reduction of the settling time and the elimination of the steady state error and overshoot

Efeito da irrigação no estabelecimento de plântulas de Manduvi transplantadas Em pastagens cultivadas.

O esforço para a conservação da arara-azul no Pantanal deve enfocar a manutenção de populações viáveis de Manduvi. Caso seja diagnosticado que o recrutamento populacional de Manduvi desta árvore no Pantanal é insatisfatório para a reposição de adultos, torna-se urgente o desenvolvimento de um programa de manejo e conservação de populações de Manduvi. Neste sentido, este trabalho investigou o estabelecimento de plântulas de Manduvi, com 60 dias de semeadura, transplantadas em pastagens cultivadas, que substituíram a vegetação original na área da fazenda Nhumirim. The effort to conserve hyacinth macaws in the Pantanal should focus on the maintenance of viable populations of Manduvi. If it is diagnosed that the recruitment of this tree population in the Pantanal is unsatisfactory for the replacement of adults, it becomes urgent to develop a program management and conservation of populations of Manduvi. Thus, this study investigated the establishment of seedlings of Manduvi, with 60 days of sowing, transplanting in cultivated pastures, which replaced the original vegetation in the area of the Nhumirim Farm

The mechanisms of movement control and time estimation in cervical dystonia patients

Traditionally, the pathophysiology of cervical dystonia has been regarded mainly in relation to neurochemical abnormities in the basal ganglia. Recently, however, substantial evidence has emerged for cerebellar involvement. While the absence of neurological "cerebellar signs" in most dystonia patients may be considered at least provoking, there are more subtle indications of cerebellar dysfunction in complex, demanding tasks. Specifically, given the role of the cerebellum in the neural representation of time, in the millisecond range, dysfunction to this structure is considered to be of greater importance than dysfunction of the basal ganglia. In the current study, we investigated the performance of cervical dystonia patients on a computer task known to engage the cerebellum, namely, the interception of a moving target with changing parameters (speed, acceleration, and angle) with a simple response (pushing a button). The cervical dystonia patients achieved significantly worse results than a sample of healthy controls. Our results suggest that the cervical dystonia patients are impaired at integrating incoming visual information with motor responses during the prediction of upcoming actions, an impairment we interpret as evidence of cerebellar dysfunction

Dimensional reduction of the Standard Model coupled to a new singlet scalar field

We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar. We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the Higgs and SU(2)(L) x U(1)(y) gauge fields, identical to the one studied previously for the Standard Model. This opens up the possibility of efficiently computing the order and strength of the electroweak phase transition, numerically and nonperturbatively, in this extension of the Standard Model. Understanding the phase diagram is crucial for models of electroweak baryogenesis and for studying the production of gravitational waves at thermal phase transitions.Peer reviewe

TransNets: Learning to Transform for Recommendation

Recently, deep learning methods have been shown to improve the performance of recommender systems over traditional methods, especially when review text is available. For example, a recent model, DeepCoNN, uses neural nets to learn one latent representation for the text of all reviews written by a target user, and a second latent representation for the text of all reviews for a target item, and then combines these latent representations to obtain state-of-the-art performance on recommendation tasks. We show that (unsurprisingly) much of the predictive value of review text comes from reviews of the target user for the target item. We then introduce a way in which this information can be used in recommendation, even when the target user's review for the target item is not available. Our model, called TransNets, extends the DeepCoNN model by introducing an additional latent layer representing the target user-target item pair. We then regularize this layer, at training time, to be similar to another latent representation of the target user's review of the target item. We show that TransNets and extensions of it improve substantially over the previous state-of-the-art.Comment: Accepted for publication in the 11th ACM Conference on Recommender Systems (RecSys 2017