Two-dimensional tunneling in a SQUID

Traditionally quantum tunneling in a static SQUID is studied on the basis of a classical trajectory in imaginary time under a two-dimensional potential barrier. The trajectory connects a potential well and an outer region crossing their borders in perpendicular directions. In contrast to that main-path mechanism, a wide set of trajectories with components tangent to the border of the well can constitute an alternative mechanism of multi-path tunneling. The phenomenon is essentially non-one-dimensional. Continuously distributed paths under the barrier result in enhancement of tunneling probability. A type of tunneling mechanism (main-path or multi-path) depends on character of a state in the potential well prior to tunneling.Comment: 9 pages, 8 figure

HIV infection and aging: enhanced Interferon- and Tumor Necrosis Factor-alpha production by the CD8(+) CD28(-) T subset

BACKGROUND: T cells from HIV(+) and aged individuals show parallels in terms of suppressed proliferative activity and interleukin-2 (I1-2) production and an increased number of CD8(+) CD28(-) T cells. In order to compare cytokine production from T cells from these two states, CD4(+) and CD8(+) T cells from HIV(+) aged, and normal young donors (controls) were monitored for cytokine production by flow cytometry, quantitative PCR and ELISA upon activation by PMA and anti-CD3. In addition, the CD8(+) T cell subsets CD28(+) and CD28(-) from the HIV(+) and the aged groups were evaluated for cytokine production by flow cytometry, and compared with those from young controls. RESULTS: Flow cytometric analysis indicated that CD8(+) T cells from both HIV(+) and aged donors showed an increase of approximately 2–3 fold over controls in percentage of cells producing inflammatory cytokines IFN-γ and TNF-α. Similar analysis also revealed that the production of interleukins-4,6 and 10, production was very low (1–2% of cells) and unchanged in these cells. Quantitative PCR also showed a substantial increase (4–5 fold) in IFN-γ and TNF-α mRNA from HIV(+) and aged CD8(+) T cells, as did ELISA for secreted IFN-γ and TNF-α (2.3–4 fold). Flow cytometric analysis showed that the CD8(+) CD28(-) T cell subset accounts for approximately 80–86% of the IFN-γ and TNF-α production from the CD8(+) subset in the aged and HIV(+) states. The CD4(+) T cell, while not significantly changed in the HIV(+) or aged states in terms of IFN-γ production, showed a small but significant increase in TNF-α production in both states. CONCLUSIONS: Our data appear compatible with physiologic conditions existing in HIV(+) and aged individuals, i.e. elevated serum levels and elevated CD8(+) T cell production of IFN-γ and TNF-α. Thus, the capacity for increased production of cytokines IFN-γ and TNF-α in the aged individual by the dominant CD8(+) CD28(-) subset may have a profound influence on the clinical state by aggravating inflammatory pathologies such as rheumatoid arthritis, and possibly Alzheimer's disease and Crohn's disease. In AIDS, these cytokines may contribute to wasting and cachexia. We theorize that the predominant phenotypic change to the cytotoxic CD8(+) CD28(-) T cell subsets in both the HIV(+) and the aged states may reflect a natural "endpoint" in CD8(+) T cell differentiation induced after a lifetime of immune activity (toward viruses, etc) in the aged, and after a massive accelerated response to HIV in the HIV-positive individual

Concept note for ICCAT ecoregion workshop identification of regions in the ICCAT convention area for supporting the implementation of ecosystem based fisheries management

The overall aim of the workshop is to advance in the identification of candidate ecologically meaningful regions that can serve as a basis to produce a more integrated ecosystem-based advice, and thereby support the implementation and operationalization of ecosystem-based fisheries management (EBFM) in the International Commission for the Conservation of Atlantic Tunas (ICCAT) convention area. The candidate regions should have boundaries that make ecological sense, and are practical in informing fisheries management. The workshop will gather CPC national scientists and external experts from different scientific disciplines (e.g. biogeography, oceanography, ecology, fisheries and fisheries management in the ICCAT area) to develop a “proof of concept” for broad-scale regionalization of the ICCAT convention area.L'objectif général de l'atelier est de progresser dans l'identification de possibles régions écologiquement significatives qui peuvent servir de base pour produire un avis écosystémique plus intégré, et ainsi soutenir la mise en œuvre et la mise en marche de la gestion des pêcheries basée sur les écosystèmes (EBFM) dans la zone de la Convention de la Commission internationale pour la conservation des thonidés de l'Atlantique (ICCAT). Les régions candidates doivent avoir des limites qui ont un sens écologique, et qui sont pratiques pour renseigner la gestion des pêcheries. L'atelier réunira des scientifiques nationaux des CPC et des experts externes de différentes disciplines scientifiques (par exemple, la biogéographie, l'océanographie, l'écologie, la pêche et la gestion des pêcheries dans la zone de l'ICCAT) afin de développer une preuve conceptuelle pour une régionalisation à grande échelle de la zone de la Convention ICCATEl objetivo global del taller es avanzar en la identificación de posibles regiones ecológicamente significativas que puedan servir como base para formular un asesoramiento basado en el ecosistema más integrado, apoyando la implementación y puesta en marcha de la ordenación pesquera basada en el ecosistema (EBFM) en la zona del Convenio de la Comisión Internacional para la Conservación del Atún Atlántico (ICCAT). Las regiones candidatas deberían tener límites que tengan sentido ecológico y que sean prácticas para aportar información a la ordenación pesquera. El taller reunirá a científicos nacionales de las CPC y a expertos externos de diversas disciplinas (por ejemplo, biogeografía, oceanografía, ecología, pesca y ordenación pesquera en la zona de ICCAT) para desarrollar una demostración conceptual para una regionalización a gran escala de la zona del Convenio de ICCAT.Versión del edito

Distribución espacial de la precipitación sobre el crecimiento inicial del cedro rojo (Cedrela odorata L.)

Objective: To analyze the effect of the spatial variability of precipitation on the initialgrowth of red cedar (Cedrella odorata L.) in Soconusco, Chiapas, Mexico.Design / methodology / approach: The plantations were established in June 2010 inSuchiate, Tapachula and Tuxtla Chico, Chiapas; with a density of 1,111 trees ha -1planted and spaced 3.0 mx 3.0 m. Every six months (210-2014) tree height (h; m) anddiameter at chest height (DBH; cm) were measured).Results: The average annual height of the trees was correlated; with the accumulatedannual precipitation (Pp; mm), and a simple linear regression equation (R2= 0.94) wasdetermined, which predicts that the growth of the red cedar was 0.09 m for every 100mm of precipitation observed in the different localities. Likewise, its initial growth wasadjusted with a high level of confidence (P?0.001) to the first phase of the Richardssigmoidal model and, from its first derivative, the annual growth rates were determined:2.58 m year-1, 2.05 year -1 and 1.86 year -1 m for the towns of Tapachula, Tuxtla Chicoand Suchiate, respectively.Study limitations / implications: The first phase of the Richards model is onlyapplicable for the initial growth of red cedar and, beyond four years of age, it presentserrors. 2Conclusions: The first phase of Richards' sigmoidal model under the conditionsstudied, predicts with high confidence the initial growth of red cedar for the conditions ofSoconusco, Chiapas.Objetivo: Analizar el efecto de la variabilidad espacial de la precipitación sobre el crecimiento inicial del cedro rojo (Cedrella odorata L.) en el Soconusco; Chiapas, México.Diseño/metodología/aproximación: Las plantaciones se establecieron en junio de 2010 en Suchiate, Tapachula y Tuxtla Chico, Chiapas; con una densidad de 1,111 árboles ha -1 sembrados y espaciados 3.0 m x 3.0 m. Cada seis meses (210-2014) se midieron altura del árbol (h; m) y diámetro a la altura del pecho (DAP; cm).Resultados: Se correlacionó la altura promedio anual de los árboles; con la precipitación anual acumulada (Pp; mm), y se determinó una ecuación de regresión lineal simple (R 2 =0.94), la cual predice que, el crecimiento del cedro rojo fue de 0.09 m por cada 100 mm de precipitación observada en las diferentes localidades. Asimismo, su crecimiento inicial se ajustó con alto nivel de confianza (P?0.001) a la primera fase del modelo sigmoidal de Richards y, a partir de su primera derivada, se determinaron las tasas de crecimiento anual: 2.58 m año -1 , 2.05 m año -1 y 1.86 m año -1 para las localidades de Tapachula, Tuxtla Chico y Suchiate, respectivamente.Limitaciones del estudio/implicaciones: La primera fase del modelo Richards, sólo es aplicable para el crecimiento inicial del cedro rojo y, más allá de cuatro años de edad presenta errores.Hallazgos/conclusiones: La primera fase del modelo sigmoidal de Richards bajo lascondiciones estudiadas, predice con alto nivel de confianza el crecimiento inicial delcedro rojo para las condiciones del Soconusco, Chiapas

Intrapericardial delivery of apa-microcapsules as promising stem cell therapy carriers in an experimental acute myocardial infarction model

The administration of cardiosphere-derived cells (CDCs) after acute myocardial infarction (AMI) is very promising. CDC encapsulation in alginate-poly-L-lysine-alginate (APA) could increase cell survival and adherence. The intrapericardial (IP) approach potentially achieves high concentrations of the therapeutic agent in the infarcted area. We aimed to evaluate IP therapy using a saline vehicle as a control (CON), a dose of 30 × 106 CDCs (CDCs) or APA microcapsules containing 30 × 106 CDCs (APA-CDCs) at 72 h in a porcine AMI model. Magnetic resonance imaging (MRI) was used to determine the left ventricular ejection fraction (LVEF), infarct size (IS), and indexed end diastolic and systolic volumes (EDVi; ESVi) pre-and 10 weeks post-injection. Programmed electrical stimulation (PES) was performed to test arrhythmia inducibility before euthanasia. Histopathological analysis was carried out afterwards. The IP infusion was successful in all animals. At 10 weeks, MRI revealed significantly higher LVEF in the APA-CDC group compared with CON. No significant differences were observed among groups in IS, EDVi, ESVi, PES and histopathological analyses. In conclusion, the IP injection of CDCs (microencapsulated or not) was feasible and safe 72 h post-AMI in the porcine model. Moreover, CDCs APA encapsulation could have a beneficial effect on cardiac function, reflected by a higher LVEF at 10 weeks. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Evaluación funcional de sistemas sensoriales mediante potenciales evocados en niños con trastornos del espectro autista

Objective: To evaluate the possible sensorial affectation of the somesthetic system in children with speech disorders, mainly with the autistic spectrum disorders (ASD)through the use of the recording technique for somatosensory evoked potential (SEP).Subjects and methods: We performed a longitudinal retrospective study on 40 children remitted to CIREN'S Laboratory of Evoked Potentials from August 2000 to May 2009. The children presented disorders in language acquisition, most of them within the ASD. The sample was composed of 24 males and 16 females (aged between 2 and 13 years of age). To obtain SEP, recording electrodes were applied on the L4-T12 lumbar region (plexus derivation) and in Cz-Fz cortical region, by stimulating the posterior tibial nerve. Additionally, the auditory brainstem response (ABR) was performed to discard functional disorders of the auditory pathway.Results: 92% of the children studied showed alterations in SEP, of which 65% was related to an increment of central conduction time (CCT); 10% had no bilateral cortical response and 12.5% presented morphologic distortion of the evoked cortical response.ABR was conducted on 29 of the 40 studied children, and it was observed that 75.8% were normal and only 24.1% presented anomalies. Of these, 5 were related to affectation of wave I, another presented bilateral hypoacusia and the remaining one had no evoked response, where the bilateral form of dysfunction predominated.Conclusions: Our results suggest a possible relation between the dysfunction of the somesthetic system and language retard. The affectation of this system was greater than the auditory ones in the patients studied.Objetivo: Evaluar mediante el empleo de la técnica de registro de potencial evocado somatosensorial de nervio tibial posterior (PESSt) la posible afectación sensorial del sistema somestésico en niños con trastornos del lenguaje, en particular con trastornos del espectro autista (TEA).Sujetos y Métodos: Realizamos un estudio retrospectivo longitudinal en 40 niños remitidos al Laboratorio de Potenciales Evocados del CIREN en el período comprendido entre agosto del 2000 y mayo del 2009 por presentar trastornos en la adquisición del lenguaje, en su mayoría dentro del espectro autista. La muestra estuvo conformada por 24 varones y 16 hembras (edades entre 2 y 13 años). Para la obtención del PESSt se colocaron electrodos de registro en región lumbar L4- T12 (derivación de plexo) y en región cortical Cz- Fz, estimulando el nervio tibial posterior. Adicionalmente se realizó el potencial evocado auditivo de tallo cerebral (PEATC) para descartar la presencia de afectaciones en la vía auditiva.Resultados: Del total de niños estudiados el 92.5 % mostró alteraciones en el PESSt, de las cuales el 65 % estuvo relacionada con el incremento del tiempo de conducción central (TCC), un 10 % tuvo ausencia de respuesta cortical bilateral, y el 12,5 % presentó distorsión morfológica de la respuesta evocada cortical.En tanto el PEATC se realizó a 29 de los 40 niños estudiados, observando que el 75,8 % fueron normales y solo el 24,1 % presentaron anomalías en el estudio, de estos 5 estuvieron relacionados con afectación de la onda I, otro presentaba hipoacusia bilateral y el caso restante no tuvo respuesta evocada, predominando la afectación de forma bilateral.Conclusiones: Nuestros resultados muestran una alta incidencia de afectación en el sistema somestésico de niños con TEA. La afectación de este sistema fue mayor que la de los auditivos en los pacientes estudiados

Medición del calor latente de vaporización del nitrógeno líquido en la enseñanza de la física experimental

Among the methods for teaching physics, one of the more instructive is the experiment, we presents a simple and inexpensive for the indirect measurement of the latent heat of vaporization of liquid nitrogen using typical elements of a general physics laboratory, such as resistors, voltage sources, multimeters, timers and a balance, with the latter measures the mass change in a container of liquid nitrogen with respect to the time, when the nitrogen is heated with a resistance when it passes by an electric current, we found a proportionality between the electric power supplied to nitrogen, time and the mass of Nitrogen evaporated, which relate to the latent heat of vaporization of nitrogen.Entre los métodos para la enseñanza de la física, uno de los más didáctico es el experimento, en este trabajo, se presenta una forma sencilla y económica para la medición indirecta del calor latente de vaporización del nitrógeno líquido utilizando elementos típicos de un laboratorio de física general, como son las resistencias, fuentes de voltajes, multímetros, cronómetros y una balanza, con ésta última se mide la variación de la masa en un recipiente que contiene nitrógeno liquido con respecto al tiempo, cuando se calienta el nitrógeno con una resistencia al hacer pasar por ésta una corriente eléctrica,encontramos una proporcionalidad entre la potencia eléctrica suministrada al nitrógeno, el tiempo y la masa de N2 evaporada, las cuales se relacionan con el calor latente de vaporización del nitrógeno