Annihilation of Dipolar Dark Matter to Photons

In this work we study the annihilation of fermionic dark matter, considering it as a neutral particle with nonvanishing magnetic ($M$) and electric ($D$) dipole moments. Effective cross-section of the process $\chi \overline{\chi} \rightarrow \gamma \gamma$ is computed starting from a general form of coupling $\chi \overline{\chi} \gamma$ in the framework of an extension of the Standard Model. By taking into account annihilation of DM pairs into mono-energetic photons, we found that for small masses, $m_\chi \leq 10\,\textrm{GeV}$, an electric dipole moment $\sim 10^{-16}\, \textrm{e cm}$ is required to satisfy the current residual density inferences. Additionally, in order to pin down models viable to describe the physics of dark matter at the early Universe we also constrain our model according to recent measurements of the temperature anisotropies of the cosmic background radiation, we report constraints to the electric and magnetic dipole moments for a range of masses within our model.Comment: 20 pages, 6 figure

Estudio de los efectos de algunos psicotropos en el test "Open Field"

Por medio del test "opcn-field" se ha analizado el comportamiento de ratas tratadas con diversos psicotropos ncurolépt icos. antidcpresivos, tranquilizntes, barbitú ricos, psicoana l~pt icos) y asociaciones, entre las que figura la de un IMAO (nialamida) y 5-hidroxitriptofano, precusor de la serotonina cerebral. De los resultados obtenidos se deduce que los neurolépticos dieron lugar a una marcada reducción de la motilidad, en tanto que el clordiacepóxido y el fenobarbilal produjeron el efecto con· trario, probablemente como expresión de un efecto ansiolítico notable. La asociación de nialamida y 5-hidroxitriptofano dió lugar a una reducción muy significativa de la deambulación de las ratas tratadas, sugiriéndose una participación de la serotonina en los circuitos moduladores de la actividad de las ratas. Este descenso de movilidad fue hallado, asimtsmo, con la imipramina, r~lacio nándose también, este fenómeno, con una posible intensificación de sistemas serotoninérgicos. En cuanto a la intervención de los psicotropos sobre las estereotipias y las emisiones de bolos fecales, no se han encontrado resultados capaces de informar con eficacia, sobre la utilidad de estos dos parámetros como medida para la "emotividad"

Fully relativistic calculation of magnetic properties of Fe, Co and Ni adclusters on Ag(100)

We present first principles calculations of the magnetic moments and magnetic anisotropy energies of small Fe, Co and Ni clusters on top of a Ag(100) surface as well as the exchange-coupling energy between two single adatoms of Fe or Co on Ag(100). The calculations are performed fully relativistically using the embedding technique within the Korringa-Kohn-Rostoker method. The magnetic anisotropy and the exchange-coupling energies are calculated by means of the force theorem. In the case of adatoms and dimers of iron and cobalt we obtain enhanced spin moments and, especially, unusually large orbital moments, while for nickel our calculations predict a complete absence of magnetism. For larger clusters, the magnitudes of the local moments of the atoms in the center of the cluster are very close to those calculated for the corresponding monolayers. Similar to the orbital moments, the contributions of the individual atoms to the magnetic anisotropy energy strongly depend on the position, hence, on the local environment of a particular atom within a given cluster. We find strong ferromagnetic coupling between two neighboring Fe or Co atoms and a rapid, oscillatory decay of the exchange-coupling energy with increasing distance between these two adatoms.Comment: 8 pages, ReVTeX + 4 figures (Encapsulated Postscript), submitted to PR

Nanostructured State-of-the-Art Thermoelectric Materials Prepared by Straight-Forward Arc-Melting Method

Thermoelectric materials constitute an alternative to harvest sustainable energy from waste heat. Among the most commonly utilized thermoelectric materials, we can mention Bi2Te3 (hole and electron conductivity type), PbTe and recently reported SnSe intermetallic alloys. We review recent results showing that all of them can be readily prepared in nanostructured form by arc-melting synthesis, yielding mechanically robust pellets of highly oriented polycrystals. These materials have been characterized by neutron powder diffraction (NPD), scanning electron microscopy (SEM) and electronic and thermal transport measurements. Analysis of NPD patterns demonstrates near-perfect stoichiometry of above-mentioned alloys and fair amount of anharmonicity of chemical bonds. SEM analysis shows stacking of nanosized sheets, each of them presumably single-crystalline, with large surfaces parallel to layered slabs. This nanostructuration affects notably thermoelectric properties, involving many surface boundaries (interfaces), which are responsible for large phonon scattering factors, yielding low thermal conductivity. Additionally, we describe homemade apparatus developed for the simultaneous measurement of Seebeck coefficient and electric conductivity at elevated temperatures

Obtention and characterization of ferrous chloride FeCl_2•4H_2O from water pickling liquors

As a hazardous waste, water pickling liquors must be properly treated. An alternative consists of promoting the formation of ferrous salts from this residue due to their higher ferrous content. Since FeCl_2•4H_2O is widely used in several applications, obtaining pure crystals of this material appears to be an interesting prospect. However, this compound has scarcely been investigated. In the present work, FeCl_2•4H_2O crystals were obtained from water pickling liquors. Their structural and morphological characteristics were investigated by X-ray diffraction, scanning electron microscopy as well as Mossbauer spectroscopy. In addition, the photoluminescence study of the obtained samples was also assessed. It was observed that after some aging time, the obtained crystals changed in colour from green to more yellowish. As such, the aged sample was also evaluated, and their structural characteristics were compared with the original crystals. Despite this, the obtained crystals exhibit a FeCl_2•4H_2O structure, which is not modified with the aging of the sample

On-surface self-organization of a robust metal-organic cluster based on copper(i) with chloride and organosulphur ligands

Direct sublimation of a Cu4Cl4 metal-organic cluster on Cu(110) under ultra-high vacuum allows the formation of ultra-large well-organized metal-organic supramolecular wires. Our results show that the large monomers assemble with each other by π-π interactions connecting dipyrimidine units and are stabilized by the surfaceWe thank Spanish MINECO (Grants: MAT2013-46753-C2-1-P, MAT2013-47878-C2-1-R and MAT2011-26534) for financial support. JIM acknowledges a CSIC-JaeDoc fellowship, cofunded by ES

Depopulation impacts on ecosystem services in Mediterranean rural areas

Despite the exponential increase in human population at global scale, some rural areas have experienced a progressive abandonment over the last decades. Under particular socioecological and policy contexts, changes in demography may promote land-use changes and, consequently, alter ecosystem services (ES) supply. However, most studies on this topic have targeted urban population increase, whereas depopulation has been rarely addressed. Here, we examined how shifts in demographic variables (human population, population density, and number of villages) affect provisioning (water supply, food and biomass production) and regulating (soil retention, water and nutrient regulation) ES in Mediterranean rural areas with contrasting environmental, so-cioeconomic and land-use contexts. When depopulation results in underuse of socio-ecological systems, we ex-pected a decrease of provisioning and an increase of regulating ES, whereas we expected the opposite pattern when it results in land-use intensification. To test this hypothesis, we compared demographic data and ES estimated with Soil and Water Assessment Tool (SWAT) linked to land-use changes between the 1950s and 2000s in three rural areas of Arag ́on (NE Spain). Generalized Additive Mixed Models and Linear Mixed-Effect Models were used to analyze demographic trends, ES changes and the relationship between them. We found severe depopulation (− 42% inhabitants) and associated land-use changes in the three areas, which was particularly evident in isolated mountainous zones (− 63% inhabitants). Depopulation trends significantly affected land use and, consequently, all of the ES evaluated. In mountainous depopulated areas, land abandonment and rewilding resulted in the increase in water regulation (>1000%) and soil retention (>400%). In contrast, agriculture was intensified in more fertile and easy-to-access lowland areas, boosting the food production service (>600%). Accordingly, the interactions among depopulation, crop production and regulating ES should be considered in the management schemes and policies targeting rural areas for a balanced and sustainable supply of ES in the long term

Genetic association study in nasal polyposis.

[EN] Nasal polyposis (NP) is a chronic inflammatory disease of the upper airways with a variable clinical course and unknown pathogenesis that often coexists with other conditions. Considering the possibility of genetic predisposition, we decided to analyze whether polymorphisms in LTC4S, CYSLTR1, PTGDR, and NOS2A were associated with NP. The study population comprised 486 Caucasian individuals. Polyposis and aspirin intolerance were diagnosed following the recommendations of the European Position Paper on Rhinosinusitis and Nasal Polyps. Genotypes were determined using polymerase chain reaction amplification and direct sequencing. The -444A > C LTC4S polymorphism was significantly associated with NP and atopy (P = .033) and with NP and atopic asthma, (P =.012). In addition, a significant association was found when the (CCTTT) repetition of the NOS2A gene was present more than 14 times in patients with NP and asthma (P = .034), in patients with polyposis and intolerance to nonsteroidal anti-inflammatory drugs (P = .009), and in patients with the aspirin triad (P = .005). The PTGDR diplotype CCCT/CCCC (-613CC, -549CC, -441CC and -197TC) was more frequent in patients with NP (P = .043), NP with asthma (P = .013), and the aspirin triad (P = .041). NP was associated with specific polymorphisms only when it occurred with related phenotypes. Our results suggest that this genetic background plays a more relevant role in the development of the associated clinical features of nasal polyposis than in simple polyposis.Junta de Castilla y León; Merck Sharpe Dohme; Mutua Madrileñ