Degradation of LaMnO{3-y} surface layer in LaMnO{3-y}/ metal interface

We report electrical measurements showing the degradation processes of LaMnO$_{3-y}$ (LaMnO) in LaMnO/normal metal interface in both point contact and planar-type junctions. Immediately after the preparation of the interface, the degradation process was followed by measuring the evolution of the junction resistance versus time. This process is characterized by the appearance of a second maximum in the resistance vs. temperature (R-T) dependence at temperatures lower than the Curie temperature T$_c$, at which the metal-insulator transition occurs in the bulk. These effects are explained in terms of the formation of a depleted interface layer in LaMnO caused by an out-diffusion of oxygen from the manganite surface to the normal metal. This assumption is confirmed by XPS measurement. Similar results on LaSrMnO$_{3-y}$ interfaces are also obtained.Comment: 4 pages, 3 figures, accepted for publication in Appl. Phys. Lett.(2002

Perceived quality of life and the specific physical activities by the elderly

Se analizaron indicadores de salud con respecto a la percepción de la calidad de vida (CVRS) mediante el cuestionario Short Form-36 Health Survey (SF-36) y parámetros cinemáticos manifestados en el movimiento press banca (12 kilos) como predictores de las adaptaciones neurofisiológicas que se producen con la actividad física. Se trataron valores de potencia, de velocidad, aceleraciones, fuerza y variables temporales. Se utilizaron dos grupos, uno activo, de práctica física habitual (12H, 6M, 68,4±5,6 años, 1,65±0,074m, 74,57±15,41kg, BMI 26,93±4,02; act/sem 4,5±1,65h.), y otro sedentario (16H, 7M, 69 ± 7,07 años, 1,67 ± 0,072m, 74,95 ± 7,4kg, BMI 26,84±2,78) Se encontraron diferencias significativas (p<0,05;gl=1,39;dz=0,5). El grupo considerado activo se percibe con mejor calidad de vida y manifiesta de manera más rápida y con mayor fuerza el movimiento solicitado. Las conclusiones son relevantes para posteriores estudios que se centren en la pérdida de propiedades neuromusculares acompañada a la falta de práctica y al efecto del envejecimiento.Quality of life related to health indicators (QLRH) were analyzed by means of the Short Form-36 Health Survey (SF-36) questionnaire and the specified kinetic parameters of the bench press movement (12 kg) as predictors of the neurophysiological adaptations produced by physical activity. These were the values of power, velocity, acceleration, strength and temporal variables. Two groups were studied: the first group was active, undertaking regular physical activity (12 male; 6 female; 68,4±5,6 years; 1,65±0,074m; 74,57±15,41kg; BMI 26,93±4,02; weekly activity 4,5±1,65h.); the second group was sedentary (16 male; 7 female; 69±7,07 years; 1,67±0,072m; 74,95±7,4kg; BMI 26,84±2,78). Significant differences were found (p<0,05;df=1,39;dz=0,5). The group regarded as active considered itself as having a better quality of life and was able to perform the requested movement with greater speed and strength. The conclusions are relevant for future studies that centre on the loss of neuromuscular properties accompanied by a lack of physical activity and the effects of aging

A rescued dataset of sub-daily meteorological observations for Europe and the southern Mediterranean region, 1877–2012

Sub-daily meteorological observations are needed for input to and assessment of high-resolution reanalysis products to improve understanding of weather and climate variability. While there are millions of such weather observations that have been collected by various organisations, many are yet to be transcribed into a useable format. Under the auspices of the Uncertainties in Ensembles of Regional ReAnalyses (UERRA) project, we describe the compilation and development of a digital dataset of 8.8 million meteorological observations of essential climate variables (ECVs) rescued across the European and southern Mediterranean region. By presenting the entire chain of data preparation, from the identification of regions lacking in digitised sub-daily data and the location of original sources, through the digitisation of the observations to the quality control procedures applied, we provide a rescued dataset that is as traceable as possible for use by the research community. Data from 127 stations and of 15 climate variables in the northern African and European sectors have been prepared for the period 1877 to 2012. Quality control of the data using a two-step semi-automatic statistical approach identified 3.5 % of observations that required correction or removal, on par with previous data rescue efforts. In addition to providing a new sub-daily meteorological dataset for the research community, our experience in the development of this sub-daily dataset gives us an opportunity to share some suggestions for future data rescue projects. All versions of the dataset, from the raw digitised data to data that have been quality controlled and converted to standard units, are available on PANGAEA: https://doi.org/10.1594/PANGAEA.886511 (Ashcroft et al., 2018)

Shapiro steps in a superconducting film with an antidot lattice

Shapiro voltage steps at voltages V_n=nV_0 (n integer) have been observed in the voltage-current characteristics of a superconducting film with a square lattice of perforating microholes (antidots)in the presence of radiofrequent radiation. These equidistant steps appear at the second matching field H_2 when the flow of the interstitial vortex lattice in the periodic potential created by the antidots and the vortices trapped by them, is in phase with the applied rf frequency. Therefore, the observation of Shapiro steps clearly reveals the presence of mobile intersitial vortices in superconducting films with regular pinning arrays. The interstitial vortices, moved by the driving current, coexist with immobile vortices strongly pinned at the antidots.Comment: 6 pages text, 3 EPS figures, RevTeX, accepted for publication in PRB Rapid Communication

¿Es realmente fiable la evaluación no individualizada en el trabajo cooperativo?

Se presentan y discuten los resultados de una experiencia de trabajo cooperativo empleando la plataforma BSCW en alumnos de la titulación de Maestro de Educación Infantil de la Universidad de Barcelona, con el fin de detectar posibles sesgos de las coevaluaciones y las autoevaluaciones, y para valorar la incidencia que tienen los comportamientos disruptivos en el proceso cooperativo de evaluación. Los resultados muestran que el alumnado es honesto en las calificaciones que otorga, y que los comportamientos disruptivos detectados en los distintos grupos de trabajo cooperativo, causados por una baja ciudadanía de equipo, no tienen una incidencia significativa en las calificaciones otorgadas por el grupo clase. Por tanto, se legitiman las coevaluaciones y las autoevaluaciones como instrumentos fiables de evaluación en un contexto de trabajo cooperativo

Estimation of the charge carrier localization length from Gaussian fluctuations in the magneto-thermopower of La_{0.6}Y_{0.1}Ca_{0.3}MnO_3

The magneto-thermoelectric power (TEP) $\Delta S(T,H)$ of perovskite type manganise oxide $La_{0.6}Y_{0.1}Ca_{0.3}MnO_3$ is found to exhibit a sharp peak at some temperature $T^{*}=170K$. By approximating the true shape of the measured magneto-TEP in the vicinity of $T^{*}$ by a linear triangle of the form $\Delta S(T,H)\simeq S_p(H)\pm B^{\pm}(H)(T^{*}-T)$, we observe that $B ^{-}(H)\simeq 2B ^{+}(H)$. We adopt the electron localization scenario and introduce a Ginzburg-Landau (GL) type theory which incorporates the two concurrent phase transitions, viz., the paramagnetic-ferromagnetic transition at the Curie point $T_C$ and the "metal-insulator" (M-I) transition at $T_{MI}$. The latter is characterized by the divergence of the field-dependent charge carrier localization length $\xi (T,H)$ at some characteristic field $H_0$. Calculating the average and fluctuation contributions to the total magnetization and the transport entropy related magneto-TEP $\Delta S(T,H)$ within the GL theory, we obtain a simple relationship between $T^{*}$ and the above two critical temperatures ($T_{C}$ and $T_{MI}$). The observed slope ratio $B ^{-}(H)/B ^{+}(H)$ is found to be governed by the competition between the electron-spin exchange $JS$ and the induced magnetic energy $M_sH_0$. The comparison of our data with the model predictions produce $T_{C}=195K$, $JS=40meV$, $M_0=0.4M_s$, $\xi_0=10\AA$, and $n_e/n_i=2/3$ for the estimates of the Curie temperature, the exchange coupling constant, the critical magnetization, the localization length, and the free-to-localized carrier number density ratio, respectively.Comment: 6 pages (REVTEX), 2 PS figures (epsf.sty); submitted to Phys.Rev.

Force distribution in a scalar model for non-cohesive granular material

We study a scalar lattice model for inter-grain forces in static, non-cohesive, granular materials, obtaining two primary results. (i) The applied stress as a function of overall strain shows a power law dependence with a nontrivial exponent, which moreover varies with system geometry. (ii) Probability distributions for forces on individual grains appear Gaussian at all stages of compression, showing no evidence of exponential tails. With regard to both results, we identify correlations responsible for deviations from previously suggested theories.Comment: 16 pages, 9 figures, Submitted to PR

Haemosporidian parasites of Antelopes and other vertebrates from Gabon, Central Africa

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i. e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes

Investigating Executive Working Memory and Phonological Short-Term Memory in Relation to Fluency and Self-Repair Behavior in L2 Speech

This paper reports the findings of a study investigating the relationship of executive working memory (WM) and phonological short-term memory (PSTM) to fluency and self-repair behavior during an unrehearsed oral task performed by second language (L2) speakers of English at two levels of proficiency, elementary and lower intermediate. Correlational analyses revealed a negative relationship between executive WM and number of pauses in the lower intermediate L2 speakers. However, no reliable association was found in our sample between executive WM or PSTM and self-repair behavior in terms of either frequency or type of self-repair. Taken together, our findings suggest that while executive WM may enhance performance at the conceptualization and formulation stages of the speech production process, self-repair behavior in L2 speakers may depend on factors other than working memory