Behavior of early warnings near the critical temperature in the two-dimensional Ising model

Among the properties that are common to complex systems, the presence of critical thresholds in the dynamics of the system is one of the most important. Recently, there has been interest in the universalities that occur in the behavior of systems near critical points. These universal properties make it possible to estimate how far a system is from a critical threshold. Several early-warning signals have been reported in time series representing systems near catastrophic shifts. The proper understanding of these early-warnings may allow the prediction and perhaps control of these dramatic shifts in a wide variety of systems. In this paper we analyze this universal behavior for a system that is a paradigm of phase transitions, the Ising model. We study the behavior of the early-warning signals and the way the temporal correlations of the system increase when the system is near the critical point.Comment: 20 pages, 8 figures, Submitted to PLOS ONE on Oct. 20th 2014. PONE-D-14-4718

Comprehensive Plasma Metabolomic Profile of Patients with Advanced Neuroendocrine Tumors (NETs). Diagnostic and Biological Relevance

Purpose: High-throughput “-omic” technologies have enabled the detailed analysis of metabolic networks in several cancers, but NETs have not been explored to date. We aim to assess the metabolomic profile of NET patients to understand metabolic deregulation in these tumors and identify novel biomarkers with clinical potential. Methods: Plasma samples from 77 NETs and 68 controls were profiled by GC−MS, CE−MS and LC−MS untargeted metabolomics. OPLS-DA was performed to evaluate metabolomic differences. Related pathways were explored using Metaboanalyst 4.0. Finally, ROC and OPLS-DA analyses were performed to select metabolites with biomarker potential. Results: We identified 155 differential compounds between NETs and controls. We have detected an increase of bile acids, sugars, oxidized lipids and oxidized products from arachidonic acid and a decrease of carnitine levels in NETs. MPA/MSEA identified 32 enriched metabolic pathways in NETs related with the TCA cycle and amino acid metabolism. Finally, OPLS-DA and ROC analysis revealed 48 metabolites with diagnostic potential. Conclusions: This study provides, for the first time, a comprehensive metabolic profile of NET patients and identifies a distinctive metabolic signature in plasma of potential clinical use. A reduced set of metabolites of high diagnostic accuracy has been identified. Additionally, new enriched metabolic pathways annotated may open innovative avenues of clinical research

Metabolomic profile of neuroendocrine tumors (NETs) identifies methionine, porphyrin and tryptophan metabolism as key dysregulated pathways associated with patient survival

Objective: Metabolic profiling is a valuable tool to characterize tumor biology but remains largely unexplored in neuroendocrine tumors (NETs). Our aim was to comprehensively assess the metabolomic profile of NETs and identify novel prognostic biomarkers and dysregulated molecular pathways.Design and Methods: Multiplatform untargeted metabolomic profiling (GC-MS, CE-MS, and LC-MS) was performed in plasma from 77 patients with G1-2 extra-pancreatic NETs enrolled in the AXINET trial (NCT01744249) (study cohort) and from 68 non-cancer individuals (control). The prognostic value of each differential metabolite (n = 155) in NET patients (P < .05) was analyzed by univariate and multivariate analyses adjusted for multiple testing and other confounding factors. Related pathways were explored by Metabolite Set Enrichment Analysis (MSEA) and Metabolite Pathway Analysis (MPA).Results: Thirty-four metabolites were significantly associated with progression-free survival (PFS) (n = 16) and/or overall survival (OS) (n = 27). Thirteen metabolites remained significant independent prognostic factors in multivariate analysis, 3 of them with a significant impact on both PFS and OS. Unsupervised clustering of these 3 metabolites stratified patients in 3 distinct prognostic groups (1-year PFS of 71.1%, 47.7%, and 15.4% (P = .012); 5-year OS of 69.7%, 32.5%, and 27.7% (P = .003), respectively). The MSEA and MPA of the 13-metablolite signature identified methionine, porphyrin, and tryptophan metabolisms as the 3 most relevant dysregulated pathways associated with the prognosis of NETs.Conclusions: We identified a metabolomic signature that improves prognostic stratification of NET patients beyond classical prognostic factors for clinical decisions. The enriched metabolic pathways identified reveal novel tumor vulnerabilities that may foster the development of new therapeutic strategies for these patients

Ciencias de la Biología y Agronomía

Este volumen I contiene 17 capítulos arbitrados que se ocupan de estos asuntos en Tópicos Selectos de Ciencias de la Biología y Agronomía, elegidos de entre las contribuciones, reunimos algunos investigadores y estudiantes. Se presenta un Estudio Comparativo de los Recursos Hidrológico-Forestales de la Microcuenca de la Laguna de Epatlan, Pue. (1993 a 2014); la Situación Actual de la Mancha de Asfalto en Maíz (Zea mays L.) en los Municipios de Jiquipilas y Ocozocoautla, Chiapas, México; las poblaciones sobresalientes de maíz de la raza Zapalote Chico, en la Región Istmeña de Oaxaca; Se indica el índice de área foliar de cultivo de Chile Poblano mediante dos métodos en condiciones protegidas; Esquivel, Urzúa y Ramírez exploran el efecto de la biofertilización con Azospirillum en el crecimiento y producción de Jitomate; esbozan su artículo sobre la determinación del nivel de Heterosis en híbridos de Maíz para la Comarca Lagunera; una investigación sobre la estabilización de semilla de Solanum lycopersicum durante el almacenamiento y estimulación de la germinación; acotan sobre el CTAB como una nueva opción para la detección de Huanglongbing en cítricos, plantean su evaluación sobre el aluminio y cómo afecta la vida de florero de Heliconia psittacorum; indican sobre el impacto del H-564C, como un híbrido de maíz con alta calidad de proteina para el trópico húmedo de México; presetan su investigación sobre la producción de Piña Cayena Lisa y MD2 (Ananas comosus L.) en condiciones de Loma Bonita, en Oaxaca; acotan sobre el efecto de coberteras como control biológico por conservación contra áfidos en Nogal Pecanero; esbozan sobre la caracterización de cuatro genotipos de Frijol Negro en Martínez de la Torre, Veracruz, México; presentan una caracterización hidroecológica de la microcuenca de Arroyo Prieto, Yuriría, Gto., y alternativas para su restauración ambiental; presentan su investigación sobre el efecto del hongo Beauveria bassiana sobre solubilización de fosfatos y la disponibilidad de fósforo en el suelo; plantean su investigación sobre la Germinación y regeneración in vitro de Epidendrum falcatum LINDL; esbozan su artículo sobre genotipos de frijol negro y su tolerancia a sequía terminal en Veracruz, México

Efecto de la corrosión por h 2 so 4 en la difusividad térmica de acero api5l-x52

Este trabajo presenta el efecto de la corrosión por H2SO4 a pH constante de 1.4 en la difusividad térmica de acero API5L-X52. Las muestras se expusieron por 3, 6, 9, 12 y 15 días a la solución corrosiva, en un ambiente con humedad relativa promedio del 57.16% y a una temperatura de 23.6 °C. La medida de la difusividad térmica se realizó usando la técnica fotoacústica en configuración de transmisión de calor. Nuestros resultados muestran una disminución de la difusividad térmica ( a ) con el tiempo de corrosión, presentando un comportamiento que se ajusta a una curva logística del tipo decrecimiento con un límite de saturación del orden del 52% del valor inicial de A

Spatial configurations in the Ising model.

<p>Typical spatial configurations for a 2-dimensional Ising model. Three regimes are shown: a) <i>T</i> < <i>T</i>_<i>c</i>, b) <i>T</i> ≈ <i>T</i>_<i>c</i> and c) <i>T</i> > <i>T</i>_<i>c</i>. Black squares represent spins with <i>σ</i> = +1 and white one correspond to <i>σ</i> = −1.</p

Total magnetization as a function of time in the Ising model.

<p>Typical behavior of the total magnetization time series in a 2-dimensional Ising model. Three regimes are shown: a) <i>T</i> < <i>T</i>_<i>c</i>, b) <i>T</i> ≈ <i>T</i>_<i>c</i> and c) <i>T</i> > <i>T</i>_<i>c</i>. It is important to notice the change of scale between plots.</p

Temporal auto correlation at lag 1 as a function of temperature.

<p>Ensemble behavior of the autocorrelation function for lag <i>τ</i> = 1 as a function of temperature. Three regimes are shown, <i>T</i> < <i>T</i>_<i>c</i>, <i>T</i> ≈ <i>T</i>_<i>c</i> and <i>T</i> > <i>T</i>_<i>c</i>.</p

Temporal mean as a function of temperature.

<p>Ensemble behavior of the mean as a function of temperature. The mean corresponds to the total magnetization of the system. Three regimes are shown, <i>T</i> < <i>T</i>_<i>c</i>, <i>T</i> ≈ <i>T</i>_<i>c</i> and <i>T</i> > <i>T</i>_<i>c</i>. Note that the mean can also approach −1 at low temperatures; we only show here the positive values.</p

Spatial configurations in the Ising model.

<p>Typical spatial configurations for a 2-dimensional Ising model. Three regimes are shown: a) <i>T</i> < <i>T</i>_<i>c</i>, b) <i>T</i> ≈ <i>T</i>_<i>c</i> and c) <i>T</i> > <i>T</i>_<i>c</i>. Black squares represent spins with <i>σ</i> = +1 and white one correspond to <i>σ</i> = −1.</p