Rate-induced tipping and saddle-node bifurcation for quadratic differential equations with nonautonomous asymptotic dynamics

An in-depth analysis of nonautonomous bifurcations of saddle-node type for scalar differential equations $x'=-x^2+q(t)\,x+p(t)$, where $q\colon\R\to\R$ and $p\colon\R\to\R$ are bounded and uniformly continuous, is fundamental to explain the absence or occurrence of rate-induced tipping for the differential equation $y' =(y-(2/\pi)\arctan(ct))^2+p(t)$ as the rate $c$ varies on $[0,\infty)$. A classical attractor-repeller pair, whose existence for $c=0$ is assumed, may persist for any $c>0$, or disappear for a certain critical rate $c=c_0$, giving rise to rate-induced tipping. A suitable example demonstrates that this tipping phenomenon may be reversible.Marie Skłodowska-Curie grant agreement No 643073Ministerio de Ciencia, Innovación y Universidades, RTI2018-096523-B-I00Marie Skłodowska-Curie grant agreement No 75446

Critical transitions for scalar nonautonomous systems with concave nonlinearities: some rigorous estimates

The global dynamics of a nonautonomous Carath\'eodory scalar ordinary differential equation $x'=f(t,x)$, given by a function $f$ which is concave in $x$, is determined by the existence or absence of an attractor-repeller pair of hyperbolic solutions. This property, here extended to a very general setting, is the key point to classify the dynamics of an equation which is a transition between two nonautonomous asypmtotic limiting equations, both with an attractor-repeller pair. The main focus of the paper is to get rigorous criteria guaranteeing tracking (i.e., connection between the attractors of the past and the future) or tipping (absence of connection) for the particular case of equations $x'=f(t,x-\Gamma(t))$, where $\Gamma$ is asymptotically constant. Some computer simulations show the accuracy of the obtained estimates, which provide a powerful way to determine the occurrence of critical transitions without relying on a numerical approximation of the (always existing) locally pullback attractor.Comment: 43 pages, 5 figure

Critical transitions in piecewise uniformly continuous concave quadratic ordinary differential equations

Producción CientíficaA critical transition for a system modelled by a concave quadratic scalar ordinary differential equation occurs when a small variation of the coefficients changes dramatically the dynamics, from the existence of an attractor–repeller pair of hyperbolic solutions to the lack of bounded solutions. In this paper, a tool to analyze this phenomenon for asymptotically nonautonomous ODEs with bounded uniformly continuous or bounded piecewise uniformly continuous coefficients is described, and used to determine the occurrence of critical transitions for certain parametric equations. Some numerical experiments contribute to clarify the applicability of this tool.Ministerio de Ciencia, Innovación y Universidades (under project RTI2018-096523-B-I00)Universidad de Valladolid (under proyect PIP-TCESC-2020)European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 754462Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

Exploiting optical near fields for phase change memories

We apply a recently developed technique based on optical near fields to achieve reversible phase switching in Ge2 Sb2 Te 5 films. By placing dielectric microspheres at the film surface and exposing them to pulsed laser light, a complex intensity distribution due to the optical near field can be created at the film surface. We demonstrate writing and erasing operations of patterns through phase switching. Spheres can be removed after an operation by optical near fields without ablation. Data erasure is achieved with and without near fields. The erasure method used can be determined from the result and erased information can be retrieved although being inverted. Three distinct material states are identified within patterns, showing clear contrast and sharp borders between them, thus opening the possibility of three-level data storage. Our results suggest that optical near fields are a promising candidate for developing strategies in data storage, encryption, and multiplexing. © 2011 American Institute of Physics.Peer Reviewe

Worsening of myocardial performance index in beta-thalassemia patients despite permanently normal iron load at MRI: A simple and cheap index reflecting cardiovascular involvement?

Abstract Background Iron Overload Cardiomyopathy (IOC) due to repeated transfusions still represents the main cause of death in Thalassemia major (TM) patients. Because iron overload remains asymptomatic for long time, it is important to stratify the patients based on the risk of developing IOC before the appearance of clinical signs of heart failure. The magnetic resonance imaging (MRI) T2* may be useful but it is expensive and its MRI software has limited availability; conventional echocardiographic parameters, although easy availability, remain normal until advanced stages of IOC. Tissue Doppler Imaging (TDI) opened a new way to explore systolic and diastolic function directly or through derived index such as myocardial performance index (MPI) which has a prognostic value in different cardiomyopathies. Methods We enrolled 46 consecutive β-TM patients without clinical signs of heart failure and we tested them with echocardiography in 2011 and again in 2015. MPI of left and right ventricular lateral wall was calculated by TDI. All TM patients had a T2* MRI evaluation of the heart in the year before. Results Despite the absence of significant changes in morphological data at echo and at T2* evaluation, S′ waves of the lateral ventricular wall decrease while time passed, MPI worsened during the follow-up period and the derived systolic pulmonary artery systolic pressure (PAPs) increased in 2015 with respect to 2011. Conclusion TDI and MPI may reveal very early myocardial dysfunction in TM patients despite a normal T2* value. Together with PAPs they should be periodically checked in these patients

Lurbinectedin in patients with pretreated neuroendocrine tumours: Results from a phase II basket study

Lurbinectedin; Neuroendocrine tumours; Small cellLurbinectedina; Tumores neuroendocrinos; Célula pequeñaLurbinectedina; Tumors neuroendocrins; Cèl·lula petitaBackground Patients with neuroendocrine tumours (NETs) need alternative therapies after failure of first-line therapy. Patients and methods This phase II trial evaluated lurbinectedin, a selective inhibitor of oncogenic transcription, at 3.2 mg/m2 as a 1-h intravenous infusion every 3 weeks in 32 NETs patients treated in the second- or third-line setting. The primary efficacy endpoint was overall response rate (ORR) according to RECIST v1.1 assessed by the investigators. Secondary endpoints included duration of response (DoR), progression-free survival (PFS), overall survival (OS) and safety. Results Two of 31 evaluable patients had confirmed partial responses (ORR = 6.5%; 95%CI, 0.8–21.4%). Median DoR was 4.7 months (95% CI, 4.0–5.4 months), median PFS was 1.4 months (95% CI, 1.2–3.0 months) and median OS was 7.4 months (95% CI, 3.4–16.2 months). Lurbinectedin showed an acceptable, predictable and manageable safety profile. The most common grade 3/4 toxicity was neutropenia (40.6%; grade 4, 12.4%; febrile neutropenia, 3.1%). Conclusions Considering the exploratory aim of this trial that evaluated a heterogeneous population of NETs patients, and the signs of antitumour activity observed (two confirmed partial responses and seven long disease stabilisations), further development of lurbinectedin is warranted in a more selected NETs population

Leptophlebiidae (Insecta: Ephemeroptera) from Gorgona Island National Natural Park (Tropical Eastern Pacific, Colombia) with the description of two new species

Gorgona National Natural Park comprises Gorgona and Gorgonilla Islands, located in the Colombian Pacific at 35 km from mainland. A large-scale study was conducted in Gorgona including samples from benthos and aereal nets and traps during five fieldworks. We here focus on the family Leptophlebiidae, describing two new species and giving data of four additional species. Terpides iguapoga sp. n. is described and illustrated from nymphs and adults, and can be characterized by the following characters, in the nymph: fore trochanter and femur with row of strong spine-like setae on inner margin, gills with blackish tracheae, posterolateral projections present on terga VI and VIII–IX; in the adult: upper portion of eyes orangeish white, forewing membrane hyaline tinged with yellowish around crossveins and marginal intercalary veins, genitalia with penes abruptly narrowing on distal third. Thraulodes insular sp. n. is described from nymphs and adults and diagnosed as follows, in the nymph: abdominal gills with narrow lamellae, femora with black streak near apex; in the imago: forewing costal area basal to bulla without crossveins, a spot and a band on femora, terga II–VI translucent white, terga VII–X darker, posterior margin of subgenital plate triangular, penes spines short and robust. We give new geographic records for four additional species: Farrodes caribbianus, Farrodes roundsi, Hagenulopsis esmeralda and Hagenulopsis zunigae. Ecological data and distributional maps are provided. Leptophlebiidae presents a reduced diversity in relation to mainland; in general the species recorded show a geographic relation to the Chocoan-Caribbean and Andean mayfly faunas.Fil: Zuñiga, Maria del Carmen. Universidad del Valle; ColombiaFil: Molineri, Carlos. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Tucuman. Instituto de Biodiversidad Neotropical; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Tucuman. Instituto de Biodiversidad Neotropical; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Cardona, William. Universidad del Valle; Colombi

A BRAIN study to tackle image analysis with artificial intelligence in the ALMA 2030 era

An ESO internal ALMA development study, BRAIN, is addressing the ill-posed inverse problem of synthesis image analysis employing astrostatistics and astroinformatics. These emerging fields of research offer interdisciplinary approaches at the intersection of observational astronomy, statistics, algorithm development, and data science. In this study, we provide evidence of the benefits of employing these approaches to ALMA imaging for operational and scientific purposes. We show the potential of two techniques, RESOLVE and DeepFocus, applied to ALMA calibrated science data. Significant advantages are provided with the prospect to improve the quality and completeness of the data products stored in the science archive and overall processing time for operations. Both approaches evidence the logical pathway to address the incoming revolution in data rates dictated by the planned electronic upgrades. Moreover, we bring to the community additional products through a new package, ALMASim, to promote advancements in these fields, providing a refined ALMA simulator usable by a large community for training and/or testing new algorithms.Comment: 9 pages, 5 figures, MaxEnt2023 conferenc