Por unas ciencias ambientales y unas ciencias de la tierra : reflexiones críticas y propuestas para un debate

Earth and Environmental Sciences are analysed in criticism form. A differentiation of Environmental Sciences and Earth Sciences as different subjects is proposed. In the case of Environmental Sciences, a «taxonomy» of contents is included with the purpose of facilitating the programme of the subject. Environmental Sciences should be a trunk subject for all the students in PostObligatory Secondary Education («bachillerato»), while Earth Sciences, a new suggested subject, should be a subject only for the modality of Sciences

Tribological behavior of functionalized 1-2 layered graphene/uhmwpe composites

In this work we present the evaluation of pristine and functionalized graphene as reinforcements for UHMWPE-based composites. These composites were manufactured by physically blending graphene particles and medical grade UHMWPE powder followed by a thermo-compression process. Mechanical behaviour by means of uniaxial tension and biaxial load by small punch were carried out. Friction coefficient and wear rate were measured. In some cases composites enhanced stiffness and yield stress, although with loss of toughness. This mechanical behaviour was recuperated after a thermal treatment. Small positive changes were obtained with some graphene concentrations respect to the friction coefficient. However, 20 % of reduction in wear rate was obtained when the graphene was functionalized. In general these composites present a good trend to be a potential alternative to the current highly crosslinked polyethylenes.We thank the Ministry of Science and Education of Spain by means of the projects MAT2010-16175) and CONSOLIDER CSD2008-00023 (FUNCOAT) for financial suppor

Do non-crop areas and landscape structure influence dispersal and population densities of male olive moth?

The permeability of the crop surroundings to pests and the landscape structure can influence pest dispersal between crop patches as well as its abundance within the crop. In this work, we analyzed the dispersal of the olive moth Prays oleae (Bernard) throughout the olive grove surroundings and their abundance within the crop following three approaches: (i) pollen grains settled on bodies of olive moths collected in olive groves were identified and compared with flora occurring on the surrounding patches; (ii) the capability of P. oleae males to penetrate non-crop patches was analyzed (iii) the effect of the landscape structure on the abundance of the three generations of the olive moth was studied. Pollen grains of scrubs and other trees occurring in the crop surroundings, such as Cistus sp., Quercus sp., Juniperus-type or Pinaceae were identified on P. oleae bodies suggesting that P. oleae penetrates into non-crop habitats. Additionally, woody and, to a lesser degree, herbaceous patches, did not constitute barriers for P. oleae. Finally, more complex and heterogeneous patches presented lower numbers of captures of P. oleae. These results give new insights into the movements of the olive moth in the olive grove surroundings and suggest that the management of non-crop areas could influence this pest abundance.info:eu-repo/semantics/publishedVersio

Influence of processing conditions on microstructural, mechanical and tribological properties of graphene nanoplatelet reinforced UHMWPE

Ultra-high molecular weight polyethylene (UHMWPE) is a relevant thermoplastic in industry and a well-proven standard biomaterial in joint replacements. To enhance its tribological properties while preserving its bulk ones, composite coatings on a UHMWPE substrate were prepared using non-functionalised graphene nanoplatelet (GNP) at reinforcement concentration of 0.1–5 wt% and two mechanical mixing techniques (ball mill or blade mixer) with different consolidation temperatures of 175–240 °C. Changes in morphology and size of the UHMWPE particles before hot-pressing were observed in function of the mechanical mixing techniques applied. Wear rate was affected by graphene content, reaching a minimum at 0.5 wt% GNP, with a reduction of 20 and 15%, for ball milling and blade mixer, respectively. However, blade mixer increased the wear rate by around twice respect the ball milling results, for all the studied materials. The coefficient of friction decreased notably, by ~25%, below 3 wt% GNP content, and hardness increased by 24%, regardless of the mechanical mixing process used. Finally, consolidation temperature had a positive influence on wear rate at temperatures of around 195 °C, which could be related to the free radical scavenger effect of the GNP

Electronic Properties of Ultra-Thin Aluminum Nanowires

We have carried out first principles electronic structure and total energy calculations for a series of ultrathin aluminum nanowires, based on structures obtained by relaxing the model wires of Gulseren et al. The number of conducting channels is followed as the wires radius is increased. The results suggest that pentagonal wires should be detectable, as the only ones who can yield a channel number between 8 and 10.Comment: 9 pages + 3 figures, to appear on Surface Scienc

Análisis mediante SIG de los parámetros de producción de escorrentía

El umbral de escorrentía (P0) constituye uno de los parámetros clave en el estudio de la respuesta hidrológica de una cuenca. Resulta fundamental para el estudio de episodios y hace referencia a las pérdidas de precipitación, que tienen lugar en el sistema fluvial, desde el inicio del mismo hasta que se produce escorrentía. Uno de los métodos más usado para la estimación de este umbral es el desarrollado por el US Soil Conservation Service –SCS- (1972). Este método utiliza, entre otros, valores de pendiente, vegetación, usos del suelo y características hidrológicas del suelo. Aunque los valores de las tablas originales han sido modificados para el caso español por Témez, la experiencia demuestra que, en ambientes de rambla, se necesita una mayor adaptación, dada la especificidad del entorno morfoclimático. Este trabajo propone algunas modificaciones al método para mejorar la estimación del umbral de escorrentía en ramblas mediterráneas. Se presenta una aproximación, mediante SIG, al cálculo del P0 en el Bco de Carraixet, incluyendo el análisis de las características hidrogeomorfológicas de la cuenca para la estimación de la infiltración del suelo. Además, la estimación del parámetro en varias fechas permite un estudio diacrónico, que pone de manifiesto la evolución espacio-temporal de la producción de escorrentía, en función de los cambios en el uso del suelo

Electron Mass Anomalous Dimension at O(1/N^2_f) in Quantum Electrodynamics

The critical exponent corresponding to the renormalization of the composite operator $\bar{\psi}\psi$ is computed in quantum electrodynamics at O(1/\Nf^2) in arbitrary dimensions and covariant gauge at the non-trivial zero of the $\beta$-function in the large \Nf expansion and the exponent corresponding to the anomalous dimension of the electron mass which is a gauge independent object is deduced. Expanding in powers of $\epsilon$ $=$ $2$ $-$ $d/2$ we check it is consistent with the known three loop perturbative structure and determine the subsequent coefficients in the coupling constantComment: 12 pages (latex), 1 figure (available from author on request), LTH-31

The Nambu-Jona-Lasinio Model at O(1/N^2)

We write down the anomalous dimensions of the fields of the Nambu--Jona-Lasinio model or chiral Gross Neveu model with a continuous global chiral symmetry for the two cases $U(1)$ $\times$ $U(1)$ and $SU(M)$ $\times$ $SU(M)$ at $O(1/N^2)$ in a $1/N$ expansion.Comment: 9 latex pages, 4 figures (available on request from the author), LTH-308, (2 eqns corrected

Oxygen in metabolic dysfunction and its therapeutic relevance

Significance: In recent years, a number of studies have shown altered oxygen partial pressure at a tissue level in metabolic disorders, and some researchers have considered oxygen to be a (macro) nutrient. Oxygen availability may be compromised in obesity and several other metabolism-related pathological conditions, including sleep apnea-hypopnea syndrome, the metabolic syndrome (which is a set of conditions), type 2 diabetes, cardiovascular disease, and cancer. Recent Advances: Strategies designed to reduce adiposity and its accompanying disorders have been mainly centered on nutritional interventions and physical activity programs. However, novel therapies are needed since these approaches have not been sufficient to counteract the worldwide increasing rates of metabolic disorders. In this regard, intermittent hypoxia training and hyperoxia could be potential treatments through oxygen-related adaptations. Moreover, living at a high altitude may have a protective effect against the development of abnormal metabolic conditions. In addition, oxygen delivery systems may be of therapeutic value for supplying the tissue-specific oxygen requirements. Critical Issues: Precise in vivo methods to measure oxygenation are vital to disentangle some of the controversies related to this research area. Further, it is evident that there is a growing need for novel in vitro models to study the potential pathways involved in metabolic dysfunction to find appropriate therapeutic targets. Future Directions: Based on the existing evidence, it is suggested that oxygen availability has a key role in obesity and its related comorbidities. Oxygen should be considered in relation to potential therapeutic strategies in the treatment and prevention of metabolic disorders

Design and validity of a choice-modeling questionnaire to analyze the feasibility of implementing physical activity on prescription at primary health-care settings

Worldwide health policies are trying to implement physical activity on prescription (PAP) at healthcare settings. However, there is not a proper methodology to analyze PHC organizational staff factors. This study aims to validate two questionnaires to assess the self-perception of nurses and general practitioners to implement PAP at primary healthcare (PHC) settings. The designed choice-modeling Google-form questionnaire was sent to 11 expert nurses and 11 expert sports medicine physicians. Experts evaluated each question on a 1–5 points Likert-type scale according to their expertise. Aiken’s V coefficient values =0.75 were used to validate separately each question using the Visual Basic-6.0 software. A total of 10 sports medicine physicians and 10 nurses with 28.4 ± 5.1 y and 16.3 ± 11.8 y of PAP experience, respectively, validated the questionnaire. One expert in each group was not considered for offering 3 ± SD answers in =2 questions respect to the mean of the rest of experts. Final Aiken’s V coefficient values were 0.89 (0.77–1.00) for the nurses’ questionnaire and 0.84 (0.77–0.95) for the physicians’ one. The questionnaires designed to assess the PAP self-perception of PHC nurses and physicians were validated. This methodology could be used to analyze PHC organizational staff factors in order to achieve an efficient PAP implementation in other PHC contexts