Breathers in inhomogeneous nonlinear lattices: an analysis via centre manifold reduction

We consider an infinite chain of particles linearly coupled to their nearest neighbours and subject to an anharmonic local potential. The chain is assumed weakly inhomogeneous. We look for small amplitude discrete breathers. The problem is reformulated as a nonautonomous recurrence in a space of time-periodic functions, where the dynamics is considered along the discrete spatial coordinate. We show that small amplitude oscillations are determined by finite-dimensional nonautonomous mappings, whose dimension depends on the solutions frequency. We consider the case of two-dimensional reduced mappings, which occurs for frequencies close to the edges of the phonon band. For an homogeneous chain, the reduced map is autonomous and reversible, and bifurcations of reversible homoclinics or heteroclinic solutions are found for appropriate parameter values. These orbits correspond respectively to discrete breathers, or dark breathers superposed on a spatially extended standing wave. Breather existence is shown in some cases for any value of the coupling constant, which generalizes an existence result obtained by MacKay and Aubry at small coupling. For an inhomogeneous chain the study of the nonautonomous reduced map is in general far more involved. For the principal part of the reduced recurrence, using the assumption of weak inhomogeneity, we show that homoclinics to 0 exist when the image of the unstable manifold under a linear transformation intersects the stable manifold. This provides a geometrical understanding of tangent bifurcations of discrete breathers. The case of a mass impurity is studied in detail, and our geometrical analysis is successfully compared with direct numerical simulations

The role of premorbid iq and age of onset as useful predictors of clinical, functional outcomes, and recovery of individuals with a first episode of psychosis

Background: premorbid IQ (pIQ) and age of onset are predictors of clinical severity and long-term functioning after a first episode of psychosis. However, the additive influence of these variables on clinical, functional, and recovery rates outcomes is largely unknown. Methods: we characterized 255 individuals who have experienced a first episode of psychosis in four a priori defined subgroups based on pIQ (low pIQ < 85; average pIQ = 85) and age of onset (early onset < 18 years; adult onset = 18 years). We conducted clinical and functional assessments at baseline and at two-year follow-up. We calculated symptom remission and recovery rates using the Positive and Negative Symptoms of Schizophrenia Schedule (PANSS) and the Global Assessment Functioning (GAF or Children-GAF). We examined clinical and functional changes with pair-wise comparisons and two-way mixed ANOVA. We built hierarchical lineal and logistic regression models to estimate the predictive value of the independent variables over functioning or recovery rates. Results: early-onset patients had more severe positive symptoms and poorer functioning than adult-onset pa-tients. At two-year follow-up, only early-onset with low pIQ and adult-onset with average pIQ subgroups differed consistently, with the former having more negative symptoms (d = 0.59), poorer functioning (d = 0.82), lower remission (61% vs. 81.1%), and clinical recovery (34.1% vs. 62.2%). Con-clusions: early-onset individuals with low pIQ may present persistent negative symptoms, lower functioning, and less recovery likelihood at two-year follow-up. Intensive cognitive and functional programs for these individuals merit testing to improve long-term recovery rates in this subgroup. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Hepatic levels of S-adenosylmethionine regulate the adaptive response to fasting

26 p.-6 fig.-1 tab.-1 graph. abst.There has been an intense focus to uncover the molecular mechanisms by which fasting triggers the adaptive cellular responses in the major organs of the body. Here, we show that in mice, hepatic S-adenosylmethionine (SAMe)—the principal methyl donor—acts as a metabolic sensor of nutrition to fine-tune the catabolic-fasting response by modulating phosphatidylethanolamine N-methyltransferase (PEMT) activity, endoplasmic reticulum-mitochondria contacts, β-oxidation, and ATP production in the liver, together with FGF21-mediated lipolysis and thermogenesis in adipose tissues. Notably, we show that glucagon induces the expression of the hepatic SAMe-synthesizing enzyme methionine adenosyltransferase α1 (MAT1A), which translocates to mitochondria-associated membranes. This leads to the production of this metabolite at these sites, which acts as a brake to prevent excessive β-oxidation and mitochondrial ATP synthesis and thereby endoplasmic reticulum stress and liver injury. This work provides important insights into the previously undescribed function of SAMe as a new arm of the metabolic adaptation to fasting.M.V.-R. is supported by Proyecto PID2020-119486RB-100 (funded by MCIN/AEI/10.13039/501100011033), Gilead Sciences International Research Scholars Program in Liver Disease, Acción Estratégica Ciberehd Emergentes 2018 (ISCIII), Fundación BBVA, HORIZON-TMA-MSCA-Doctoral Networks 2021 (101073094), and Redes de Investigación 2022 (RED2022-134485-T). M.L.M.-C. is supported by La CAIXA Foundation (LCF/PR/HP17/52190004), Proyecto PID2020-117116RB-I00 (funded by MCIN/AEI/10.13039/501100011033), Ayudas Fundación BBVA a equipos de investigación científica (Umbrella 2018), and AECC Scientific Foundation (Rare Cancers 2017). A.W. is supported by RTI2018-097503-B-I00 and PID2021-127169OB-I00, (funded by MCIN/AEI/10.13039/501100011033) and by “ERDF A way of making Europe,” Xunta de Galicia (Ayudas PRO-ERC), Fundación Mutua Madrileña, and European Community’s H2020 Framework Programme (ERC Consolidator grant no. 865157 and MSCA Doctoral Networks 2021 no. 101073094). C.M. is supported by CIBERNED. P.A. is supported by Ayudas para apoyar grupos de investigación del sistema Universitario Vasco (IT1476-22), PID2021-124425OB-I00 (funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe,” MCI/UE/ISCiii [PMP21/00080], and UPV/EHU [COLAB20/01]). M.F. and M.G.B. are supported by PID2019-105739GB-I00 and PID2020-115472GB-I00, respectively (funded by MCIN/AEI/10.13039/501100011033). M.G.B. is supported by Xunta de Galicia (ED431C 2019/013). C.A., T.L.-D., and J.B.-V. are recipients of pre-doctoral fellowships from Xunta de Galicia (ED481A-2020/046, ED481A-2018/042, and ED481A 2021/244, respectively). T.C.D. is supported by Fundación Científica AECC. A.T.-R. is a recipient of a pre-doctoral fellowship from Fundación Científica AECC. S.V.A. and C.R. are recipients of Margarita Salas postdoc grants under the “Plan de Recuperación Transformación” program funded by the Spanish Ministry of Universities with European Union’s NextGeneration EU funds (2021/PER/00020 and MU-21-UP2021-03071902373A, respectively). T.C.D., A.S.-R., and M.T.-C. are recipients of Ayuda RYC2020-029316-I, PRE2019/088960, and BES-2016/078493, respectively, supported by MCIN/AEI/10.13039/501100011033 and by El FSE invierte en tu futuro. S.L.-O. is a recipient of a pre-doctoral fellowship from the Departamento de Educación del Gobierno Vasco (PRE_2018_1_0372). P.A.-G. is recipient of a FPU pre-doctoral fellowship from the Ministry of Education (FPU19/02704). CIC bioGUNE is supported by Ayuda CEX2021-001136-S financiada por MCIN/AEI/10.13039/501100011033. A.B.-C. was funded by predoctoral contract PFIS (FI19/00240) from Instituto de Salud Carlos III (ISCIII) co-funded by Fondo Social Europeo (FSE), and A.D.-L. was funded by contract Juan Rodés (JR17/00016) from ISCIII. A.B.-C. is a Miguel Servet researcher (CPII22/00008) from ISCIII.Peer reviewe

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Hepatic levels of S-adenosylmethionine regulate the adaptive response to fasting

There has been an intense focus to uncover the molecular mechanisms by which fasting triggers the adaptive cellular responses in the major organs of the body. Here, we show that in mice, hepatic S-adenosylmethionine (SAMe)—the principal methyl donor—acts as a metabolic sensor of nutrition to fine-tune the catabolic-fasting response by modulating phosphatidylethanolamine N-methyltransferase (PEMT) activity, endoplasmic reticulum-mitochondria contacts, β-oxidation, and ATP production in the liver, together with FGF21-mediated lipolysis and thermogenesis in adipose tissues. Notably, we show that glucagon induces the expression of the hepatic SAMe-synthesizing enzyme methionine adenosyltransferase α1 (MAT1A), which translocates to mitochondria-associated membranes. This leads to the production of this metabolite at these sites, which acts as a brake to prevent excessive β-oxidation and mitochondrial ATP synthesis and thereby endoplasmic reticulum stress and liver injury. This work provides important insights into the previously undescribed function of SAMe as a new arm of the metabolic adaptation to fasting