Caracterización de un estrés celular manifestado por rugosidad y desorganización interna en plantas contaminadas

1 página, y dibujosUno de los problemas mas importantes del medioambiente, y de mas rigurosa actualidad, es la contaminacion de suelos por sales y metales pesados y sus efectos sobre las plantas. Actualmente aun existen muchos aspectos sobre los efectos de la contaminacion en los que es necesario profundizar como sucede en la aplicacion de herramientas matematicas que cuantifiquen los efectos producidos a nivel celular. En este trabajo estudiamos el efecto por contaminacion de Cl2Zn en hojas de Lolium rigidum Gaudin. Se eligio este compuesto debido a que el Cl es el anion mas frecuente y el Zn el contaminate metalico mas comun en los suelos contaminados del centro de España. Se observo que el Lolium rigidum crecio de manera espontanea en los suelos contaminados con dicha sal. Esta produce un gradiente osmotico entre el interior y el exterior de las celulas que provoca una deshidratacion de las mismas. Analizando secciones de hojas contaminadas y no contaminadas al microscopio electronico de transmision y al de barrido, se observan varios efectos de la contaminacion. En primer lugar existe una reduccion de la superficie de la celula del 50% que viene acompañada de un arrugamiento de la pared celular y una aparente desorganizacion de los cloroplastos del citoplasma (Figura 1). La rugosidad de la pared celular se cuantifica por medio de la anchura de la interfase, que para un caso en geometrıa circular viene dada por3: w(l, t) = { 1 N NΣ i=1 [ri(t)− ri l ]2} 1 2 L (1) donde l significa la media local sobre los subconjuntos de longitud de arco l , y {.} es la media sobre todo el sistema. Las ri representan las posiciones de los puntos de la interfase de la celula considerando como origen de referencia el centro de masas de la superficie de la celula. La anchura de la interfase escala como una ley de potencias con respecto al tama˜no de la ventana seg´un: w(l, t) ∼ tαloc (2) siendo αloc el exponente crıtico de rugosidad local. El valor promedio de este exponente para el caso de las celulas contaminadas es αloc = 0.75 mientras que para las celulas no contaminadas es αloc = 0.86. El segundo efecto de la contaminacion es la desorganizaci n interna de la celula. Los cloroplastos ocupan la mayor parte del citoplasma habiendo aumentado de tama˜no y perdiendo su forma original. Estudiando su distribucion espacial por medio de funciones de correlacion se puede observar que esta desorganizacion no es caotica sino que puede seguir un determinado patron. Este efecto, que se ha observado por primera vez, bien podrıa responder a una adaptacion celular de las plantas que toleran ambientes hostiles.Este trabajo ha sido desarrollado dentro de las actividades del proyecto REN2002-02501 del MCPeer reviewe

An Empirical Air-to-Ground Channel Model Based on Passive Measurements in LTE

In this paper, a recently conducted measurement campaign for unmanned-aerial-vehicle (UAV) channels is introduced. The downlink signals of an in-service long-time-evolution (LTE) network which is deployed in a suburban scenario were acquired. Five horizontal and five vertical flight routes were considered. The channel impulse responses (CIRs) are extracted from the received data by exploiting the cell specific signals (CRSs). Based on the CIRs, the parameters of multipath components (MPCs) are estimated by using a high-resolution algorithm derived according to the space-alternating generalized expectation-maximization (SAGE) principle. Based on the SAGE results, channel characteristics including the path loss, shadow fading, fast fading, delay spread and Doppler frequency spread are thoroughly investigated for different heights and horizontal distances, which constitute a stochastic model.Comment: 15 pages, submitted version to IEEE Transactions on Vehicular Technology. Current status: Early acces

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraisedThis research was funded by SecretaríaXeral de Investigación e Desenvolvemento—Xunta de Galicia Grupos de Referencia Competitiva (project number ED431C2018/19), and Development of a Strategic Grouping in Materials—AEMAT (grant ED431E2018/08)S

Biomarcadores a nivel de una comunidad de pasto y de una población herbácea forrajera para suelos contaminados por cobre

6 páginas, figuras y tablas estadísticas.El trabajo se propone discutir algunos parámetros que pueden ser considerados como biomarcadores en dos niveles de organización biológica, no usualmente considerados en los estudios sobre biomarcadores, para evaluar el efecto del Cu procedente de una antigua mina en suelos. Se ha elegido una comunidad de pasto aprovechada por ganado vacuno y una población de una leguminosa forrajera, por el interés que ambas tienen en la contaminación de redes tróficas. Se parte de un estudio de campo realizado en el área afectada por una mina de calcopirita en la provincia de Madrid, abandonada hace 37 años y con una escombrera actual de unos 3.500 m3. Una vez conocidos los contenidos de Cu asimilable de la escombrera y de los suelos contaminados circundantes, se tomaron muestras de la capa superficial de suelo en 5 áreas con un contenido creciente de este metal (de 40 a 2.500 ppm) para llevar a cabo dos bioensayos efectuados en condiciones controladas de invernadero: (i) seguimiento de la cobertura vegetal procedente del banco de semillas durante 8 semanas; (ii) siembra de Lupinus albus hasta el inicio de la floración (12 semanas). Los resultados obtenidos muestran que los biomarcadores a nivel de población vegetal (altura de la planta, diámetro de la hoja, longitud y anchura del folíolo, vigor de la planta y necrosis de la hoja), dan mejores resultados para revelar un efecto contaminante del cobre asimilable de los suelos que el biomarcador utilizado (cobertura vegetal) a nivel de la comunidad pascícola.Peer reviewe

Cáncer renal, 5 años de experiencia en un centro de referencia urológica regional

Antecedentes: En México, el carcinoma renal (CR) es la dieciseisava neoplasia maligna más frecuente, siendo además la doceava en mortalidad. El componente socioeconómico de los pacientes con diagnóstico de carcinoma de células renales metastásico (CCRm) en países en vías de desarrollo pudiera limitar en muchos casos el acceso a las mejores opciones terapéuticas disponibles. Objetivo Nuestro objetivo es describir las características clínicas y acceso al tratamiento de los pacientes mexicanos con CR Material y Métodos: Realizamos un análisis retrospectivo de todos los pacientes con diagnóstico de cáncer renal confirmados por histopatología y tratados en un centro de referencia uro-oncología del noreste de México de 2015 a 2019

Study of the growth pattern of juvenile European hake (Merluccius merluccius L.) using whole otoliths and length frequency distributions from commercial catches and groundfish surveys

A review of length distributions of commercial landings from bottom trawls, small gillnetters and groundfish surveys in Galicia has led to a new hypothesis about the individual growth of young hake from the Southern Stock (ICES Divisions VIlle and IXa). According to this new hypothesis, hake grow to about 20 cm in the first year of life and up to 35-40 cm during the second. This is in contrast with the more widespread belief that hake grow to about 15 em and 24 during the first and second years of life respectively. Consequences of the new hypothesis are that landings of hake from trawls and small gillnetters would be mainly composed of 1 year old hake and that they would reach first maturity at age 3. An interpretation of the pattern of otolith rings consistent with this hypothesis is that 6 months after birth a first hyaline ring is formed, probably associated with the change from pelagic to demersal life and that another hyaline zone with opaque rings evbedded in it is formed during the first winter. Although this study refers to hake from the Southern stock, it is possible that these conclusions are applicable also to hake from the Northern stock (ICES Divisions VIIIa,b, Sub-areas VI,VII and IV )

Gender Differences in Mathematics Motivation: Differential Effects on Performance in Primary Education

[Abstract] In addition to attempting to verify gender differences, this study aims to examine the explanatory potential of boys’ and girls’ attitudes toward mathematics on their performance. The sample comprised 897 students in the 5th and 6th years of primary education (450 boys and 447 girls). The results confirm what previous research has suggested, that girls tended to exhibit less positive attitudes about mathematics than their male classmates, in particular lower motivation, worse perception of competence, and higher rates of anxiety, although in all cases the effect sizes were small. Even though there no significant gender differences in academic performance, as expected, the explanatory power of attitudes toward mathematics was clearly more significant in boys than in girls (R2 = 0.194 and R2 = 0.103, respectively). The results of the regression analysis for each sample reinforce the well-known positive impact of perceived self-efficacy on mathematics performance and introduce the effect of achievement emotions of academic performance. Test anxiety in mathematics seems to only have a negative effect on boys’ grades, as this variable does not appear in the regression equation when explaining girls’ performance. In the light of control-value theory, we discuss the contingency of perceived competence and its involvement in anxiety and academic performance. Boys’ results could be affected by the levels of anxiety inasmuch as they tend to be confident in their abilities, motivated to stand out, and interested in mathematics. Whereas despite girls reporting high rates of anxiety, what may have a negative impact on their results might have more to do with a higher value placed on mathematics, as their perception of control may be low.This work was carried out with financing from the research projects EDU2013-44062-P (MINECO) and EDU2017-82984-P (MEIC

Perceived Stress and Indicators of Burnout in Teachers at Portuguese Higher Education Institutions (HEI)

The aim of this study was to examine the phenomena of burnout and perceived stress in teachers at Higher Education Institutions, as this professional class is one of the most affected by high levels of stress. A sample of 520 university teachers was used, of which 339 (65.2%) were women. The Maslach Burnout Inventory (MBI) was used to measure burnout, and the Perceived Stress Scale (PSS) was used to measure perceived stress. A sociodemographic data questionnaire produced by the authors was also applied, which consisted of questions about age, sex, experience in the teaching profession and the participants’ teaching areas. The results indicated that university teachers over 60 years old exhibited lower levels of perceived stress, as did teachers with more teaching experience (30 years or more), and those with less experience (less than 10 years). Women exhibited higher levels of perceived stress than men. Women also scored higher levels of Emotional Exhaustion in the burnout dimensions, whereas teachers will less experience (under 10 years) and teachers with more experience (more than 30 years) had the lowest scores in this dimension. Through an examination of the relation between perceived stress and the burnout dimensions, we concluded that perceived stress was directly proportional to emotional exhaustion and depersonalization; and was inversely proportional to personal accomplishment. A total of 31.3% of the variance in burnout was explained by perceived stressS

School Engagement, Academic Achievement, and Self-Regulated Learning

[Abstract] School engagement occupies a place of reference in recent educational psychology research owing to its potential to address poor school results and school dropout rates. However, there is a need for a unifying theoretical framework. The study proposed the characterization of school engagement and explored the extent to which different profiles are associated with academic performance and self-regulation. With a sample of 717 5th and 6th year primary school students, this study was carried out via the latent profile analysis (LPA). Two groups of low school engaged students—one characterized by low behavioral engagement (5.02%) and the other by low emotional engagement (6.55%)—were distinguished. The majority of participants showed moderately high (31.95%) or moderate (56.48%) levels of school engagement in its three dimensions. Students with high engagement had the best grades and managed their time and study surroundings better, were the most strategic in seeking information, and showed less maladaptive regulatory behavior. The differences between students exhibiting low behavioral and emotional engagement and those exhibiting moderate levels in these dimensions may center upon the management of contextual resources and management of information and help. This research supports the need to approach the study of school engagement by observing the combination of its emotional, behavioral, and cognitive dimensions.This study was performed thanks to financing from research project EDU2013-44062-P (MINECO) and EDU2017-82984-P (MEIC)

Single Laser Shot Spin State Switching of {Fe II (pz)[Pt(CN) 4 ]} Inside Thermal Hysteresis studied by x-ray diffraction

International audienceWe study by x-ray diffraction and optical microscopy the photoswitching, initiated by a single ns laser pulse, of the spin-crossover {Fe II (pz)[Pt(CN) 4 ]} material inside its thermal hysteresis. The single-crystal study shows that a complete conversion from low spin to high spin states can be reached with a single laser shot. Partial conversions obtained with weaker laser energy gives rise to HS domains. Our results indicate that the non-linear response to light excitation is mainly driven by the temperature jump of the crystal following laser excitation