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In this work we apply high-resolution X-ray diffractometry to the study of InGaAs/GaAs multiple quantum well structures on (001) and(lll)B GaAs substrates. The samples consisted of p-i-n diodes with a multiple quantum well embedded in the i-region and were simultaneously grown on (001) and (111)B substrates by molecular beam epitaxy. For the characterization we have used symmetric and asymmetric reflections at different azimuthal positions. The interpretation of the diffraction profiles has been possible thanks to our recently developed simulation model, which allows the calculation of any reflection regardless of the substrate orientation. X-ray results about composition and thickness are very similar in the samples simultaneously grown on both orientations as expected from our specific growth conditions. The information obtained from X-ray characterization is consistent with the results of photoluminescence and photocurrent measurements within the experimental uncertainty of the techniques. In (lll)B samples, X-ray diffractometry provides structural information which cannot be easily obtained from optical characterization techniques.
Polymetallic quartz veins, with up to 1500 ppm indium, have been discovered recently in the Sarvlaxviken area within the 1.64 Ga anorogenic multiphase Wiborg rapakivi batholith and adjacent 1.90 Ga Svecofennian crust in SE Finland. Evidence from primary fluid inclusions in the Sarvlaxviken area provides new information on the hydrothermal transport and depositional processes of metals in anorogenic granites. Fluid inclusions with variable aqueous liquid and vapour proportions (5–90 vol.% vapour) occur in quartz, cassiterite and fluorite belonging to three generations of polymetallic quartz veins. Microthermometry indicates that the veins were deposited at temperatures that range from ~500°C down to <100°C and salinities from 0 to 16 eq. mass% NaCl. Fluid inclusion data show that the depositional conditions were similar regardless of vein generation. The interpreted depositional processes involve phase separation with a combination of condensation, cooling and boiling of an initially low-salinity (<3 eq. mass% NaCl) aqueous magmatic vapour phase enriched in CO2-F-Cl-S and metals. Fluid inclusions with low salinities dominate, but higher salinities are recorded in metal-rich parts of the veins. The turbulent fluid flow, with complex geometry and temperature-salinity patterns, may explain why sulfide and/or oxide opaque minerals occur irregularly, and are locally the dominating vein minerals, but disappear completely into barren parts of the quartz veins. All fluids are considered to have been generated by the F-rich Marviken granite (and related granite dykes), which show all geochemical criteria for an ore-fertile granite. The quartz veins investigated in the adjacent Svecofennian country rocks are considered to represent the very last stage of a fluid with similar characteristics to the fluid responsible for the ore formation in the Sarvlaxviken area, but that had cooled to <100°C.
I deficiency is still a worldwide public health problem, with children being especially vulnerable. No nationwide study had been conducted to assess the I status of Spanish children, and thus an observational, multicentre and cross-sectional study was conducted in Spain to assess the I status and thyroid function in schoolchildren aged 6–7 years. The median urinary I (UI) and thyroid-stimulating hormone (TSH) levels in whole blood were used to assess the I status and thyroid function, respectively. A FFQ was used to determine the consumption of I-rich foods. A total of 1981 schoolchildren (52 % male) were included. The median UI was 173 μg/l, and 17·9 % of children showed UI<100 μg/l. The median UI was higher in males (180·8 v. 153·6 μg/l; P<0·001). Iodised salt (IS) intake at home was 69·8 %. IS consumption and intakes of ≥2 glasses of milk or 1 cup of yogurt/d were associated with significantly higher median UI. Median TSH was 0·90 mU/l and was higher in females (0·98 v. 0·83; P<0·001). In total, 0·5 % of children had known hypothyroidism (derived from the questionnaire) and 7·6 % had TSH levels above reference values. Median TSH was higher in schoolchildren with family history of hypothyroidism. I intake was adequate in Spanish schoolchildren. However, no correlation was found between TSH and median UI in any geographical area. The prevalence of TSH above reference values was high and its association with thyroid autoimmunity should be determined. Further assessment of thyroid autoimmunity in Spanish schoolchildren is desirable.
Lithopanspermia Theory has suggested that life was transferred among planets by meteorites and other rocky bodies. If the planet had an atmosphere, this transfer of life had to survive drastic temperature changes in a very short time in its entry or exit. Only organisms able to endure such a temperature range could colonize a planet from outer space. Many experiments are being carried out by NASA and European Space Agency to understand which organisms were able to survive and how. Among the suite of instruments designed for extraplanetary exploration, particularly for Mars surface exploration, a Raman spectrometer was selected with the main objective of looking for life signals. Among all attributes, Raman spectroscopy is able to identify organic and inorganic compounds, either pure or in admixture, without requiring sample manipulation. In this study, we used Raman spectroscopy to examine the lichen Squamarina lentigera biomarkers. We analyse spectral signature changes after sample heating under different experimental situations, such as (a) laser, (b) analysis accumulations over the same spot and (c) environmental temperature increase. Our goal is to evaluate the capability of Raman spectroscopy to identify unambiguously life markers even if heating has induced spectral changes, reflecting biomolecular transformations. Usnic acid, chlorophyll, carotene and calcium oxalates were identified by the Raman spectra. From our experiments, we have seen that usnic acid, carotene and calcium oxalates (the last two have been suggested to be good biomarkers) respond in a different way to environmental heating. Our main conclusion is that despite their abundance in nature or their inorganic composition the resistance to heat makes some molecules more suitable than others as biomarkers.
High quality AlN layers with full widths at half maximum values of 10 arcmin and average surface roughness (rms) of 48Å were grown by molecular beam epitaxy on Si(111) substrates. A systematic study and optimization of the growth conditions was performed in order to use these AlN layers as buffers in the growth of GaN films. Atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques were employed to determine the surface and structural quality of the layers. Best AlN films were obtained at high substrate temperatures (Tsubs>900°C) and III/V ratios close to stoichiometry. Growth conditions with III/V ratios beyond stoichiometry (Al-rich) did not further improve the crystal quality. In these cases a higher substrate temperature is needed to prevent condensation of Al on the surface. GaN films with full width at half maximum of 10 arcmin and improved optical properties were grown on top of optimized AlN buffer layers.
Two new free-living marine nematodes belonging to the family Thoracostomopsidae, subfamily Enoplolaiminae and the genera Epacanthion are described from Patagonian coastal areas, Río Negro and Chubut provinces of Argentina. In Epacanthion bicuspidatum sp. nov. the main features are: two cusps on distal mandible end; presence of two rings of eight setae in the cervical region; and eight crown-shaped setae along the body, presence of one supplement distant two cloacal body diameter (cbd) from cloacae, gubernaculum and short spicule. Epacanthion ampullatum sp. nov. is characterized by having a tubular and long pre-cloacal supplement, short spicule, presence of gubernaculum, presence of three long setae on the tip of the tail, the presence of one supplement distant three cbd from cloacae and the presence of two small cusps on the distal end of the mandible.
The Center for Epidemiologic Studies-Depression Scale (CES-D) is the most frequently used scale for measuring depressive symptomatology in caregiving research. The aim of this study is to test its construct structure and measurement equivalence between caregivers from two Spanish-speaking countries. Face-to-face interviews were carried out with 595 female dementia caregivers from Madrid, Spain, and from Coahuila, Mexico. The structure of the CES-D was analyzed using exploratory and confirmatory factor analysis (EFA and CFA, respectively). Measurement invariance across samples was analyzed comparing a baseline model with a more restrictive model. Significant differences between means were found for 7 items. The results of the EFA clearly supported a four-factor solution. The CFA for the whole sample with the four factors revealed high and statistically significant loading coefficients for all items (except item number 4). When equality constraints were imposed to test for the invariance between countries, the change in chi-square was significant, indicating that complete invariance could not be assumed. Significant between-countries differences were found for three of the four latent factor mean scores. Although the results provide general support for the original four-factor structure, caution should be exercised on reporting comparisons of depression scores between Spanish-speaking countries.
The conditions of the bentonite in an engineered barrier for HLW disposal have been simulated in a laboratory test. Six cylindrical blocks of bentonite compacted at a dry density of 1.64 g/cm3 were piled up in a hermetic Teflon cell. The total length of clay inside the cell was 60 cm. The bottom surface of the bentonite was heated at 100°C while the top surface was injected with granitic water. The duration of the test was 7.6 years. The water intake was measured during the test and, at the end, the cell was dismounted and the dry density, water content, specific surface area, mineralogy, geochemistry and swelling capacity of the clay were measured in different sections along the blocks. The material used in this test is the FEBEX bentonite.
This article examines the extent of stigma and discrimination as reported by people with a diagnosis of schizophrenia. The hypothesis is that when people express in their own words the discrimination they experience such discrimination will be found to be widespread.
Seventy-five people with a diagnosis of schizophrenia from 15 different countries were interviewed with a mixed methods instrument to assess reported discrimination. The data were analysed for frequency counts and then a thematic analysis was performed. A conceptual map is provided.
The study was a cross-cultural one but, contrary to expectations, few transnational differences were found. The main hypothesis was supported. Conversely, we found that when participants reported ‘positive discrimination’, this could as easily be conceptualised as being treated similarly to how others in society would expect to be treated.
Negative discrimination is ubiquitous and sometimes connotatively very strong, with reports of humiliation and abuse. ‘Positive discrimination’ conversely indicates that people with a mental illness diagnosis expect discrimination and are grateful when it does not occur. The literature on self-stigma is discussed and found wanting. Similarly, the theory that contact with mentally ill people reduces stigma and discrimination is not fully supported by our results.
Lattice parameters of some different chromium-doped mullites obtained by a
sol-gel route and sintered at 1650° C have been determined from X-Ray
Diffraction data as a function of both temperature and Cr contents. Profile
refinements on the X-ray diffraction diagrams have been carried out, showing
that, at temperatures between 800° and 1535° C, an anisotropic thermal
expansion takes place for the a and b
lattice parameters of the Cr-doped mullite. We show that this anisotropic
expansion is dependent on the temperature increase and the chromium content
for the different compositions of the mullite crystals.
For antiferromagnetically coupled Fe/Cr(100) multilayers the low field contribution to the resistivity, which is caused by the domain walls (DWs), is strongly enhanced at low temperatures. The low temperature resistivity increases approximately according to a power law with the exponent 0.7–1. This behaviour can be explained by the suppression of anti-localization effects by the nonuniform gauge fields caused by the domain walls. Analyses of complex low frequency magnetic susceptibility shows an enhancement of the magnetic losses at low magnetic fields, which may be related to the AC field induced DWs movement. At low temperatures (T<100K) DWs become pinned. For frequencies (102<f< 103) Hz at temperatures below 10K, this hysteretic low field peak in the magnetic losses transforms to a non-hysteretic dip for |H|< 20 Oe, indicating a possible qualitative change in the dynamics of the DWs. The frequency dependence of the dissipation at 2K, may be reasonably well fitted by the expression that describes the losses of a damped oscillator with a single relaxation time of about 10-4 sec.
We have studied the low frequency complex magnetization dynamics in Co/Al2O3/Ni80Fe20 magnetic tunnel junctions (MTJs) at temperatures between 4.2K and 300K. The measurements were carried out by using two different experimental techniques. The first method probes directly magnetic properties via DC magnetization and AC susceptibility, while the second one measures AC magnetization dynamics of the ferromagnetic electrodes near the cross area, which is related to the tunnelling resistance.
The goal of this work is to determine the properties of the stellar populations in a sample of LIRGs and ULIRGs. Using the ages as a clock we investigate: a) whether LIRGs-ULIRGs evolve into Radio Galaxies and QSOs; b) whether cool LIRGs-ULIRGs can evolve into warm LIRGs-ULIRGs; c) the merger sequence deduced from the morphological studies is reflected in the properties of the stellar populations. Using evolutionary synthesis models with high spectral resolution stellar libraries we have found that the intermediate age stellar population dominates at optical wavelengths. The stellar population in LIRGs is similar to ULIRGs and ULIRGs-QSOs transition objects.
EURECA (European Underground Rare Event Calorimeter Array) is an
astro-particle physics facility aiming to directly detect galactic dark
matter. The Laboratoire Souterrain de Modane has been selected as host
laboratory. The EURECA collaboration unites CRESST, EDELWEISS and the
Spanish-French experiment ROSEBUD, thus concentrating and focussing effort
on cryogenic detector research in Europe into a single facility. EURECA will
use a target mass of up to one ton, enough to explore WIMP – nucleon scalar
scattering cross sections in the region of 10-9 – 10-10 picobarn.
A major advantage of EURECA is the planned use of more than just one target
material (multi target experiment for WIMP identification).
The taxonomic status of the Lower Cretaceous non-marine ostracode genera Hourcqia Krömmelbein and Pattersoncypris Bate is discussed. From a detailed analysis of the type species of these genera, and several other species attributed to them, it was possible to conclude that both genera are invalid. Hourcqia africana Krömmelbein, the type species of this genus, has an antero-ventral beak, and it is in all other respects identical to Cypridea Bosquet, and therefore should be transferred to this genus. the subspecies originally referred to as Hourcqia africana confluens Krömmellbein and Weber, 1971 is subsumed within Cypridea africana. Secondly, the genus Pattersoncypris, as the result of a study of its type species, P. micropapillosa Bate, is shown to be a junior synonym of Harbinia Tsao. Both, Hourcqia and Pattersoncypris must therefore be suppressed. Cypridea africana (Krömmelbein) occurs in Brazil, Congo, and Gabon in strata deposited during the rift stage, restricted to the late Barremian to early Aptian interval. Harbinia micropapillosa (Bate) occurs in Brazil and Liberia, but it is restricted to the gulf stage, i.e. the late Aptian to early Albian interval. Amended diagnoses for the genus Cypridea and species Cypridea africana and H. micropapillosa are given.
We present a summary of the last activities of science communication
that have taken place in the Observatorio de la Universidad
Complutense de Madrid (UCM Observatory) on the occasion of the
Third Science Week of the Comunidad Autónoma de Madrid
(3–16 November 2003), including guided tours through the observatory
facilities, solar observations, and several talks. Moreover the
current telescopes, instruments and tools of the UCM Observatory
have allowed us to organize other communicating activities such
as the live observation, together with its internet broadcast,
of total lunar eclipses and other exceptional astronomical events
as the Venus transit that took place in 8 June 2004.
This study evaluated the IS6220-RFLP patterns of 109 Mycobacterium tuberculosis isolates of patients with HIV cared for at a Brazilian university hospital. Thirteen clusters involving 35 (32.1%) individuals were identified. Nosocomial transmission was possible in 5 cases. Strategies to prevent M. tuberculosis transmission should be implemented in hospitals in developing countries.
The flight activity of each of the three major leafhopper vectors of rice tungro viruses, Nephotettix virescens (Distant), N. nigropictus (Stål) and Recilia dorsalis (Motschulsky) was closely associated with rice cropping periods and was influenced by crop growth stage and season. Leafhopper flight was influenced by changing levels of illumination at dusk and dawn and, for R. dorsalis only, was significantly affected by moon phase. Recilia dorsalis was the dominant species caught in suction traps at 0.75 m and 1.5 m and an upwardly-directed light trap at 4.0 m, whereas N. virescens was the most abundant species caught on sticky yellow traps at the height of the canopy. Infectivity tests on migrant leafhoppers caught in upwardly-directed light traps showed that N. virescens was the most common transmitter of rice tungro viruses. Infective leafhoppers were recorded at the end of dry seasons and during wet seasons in 1991 and 1992. The risk of tungro disease incidence was very low early in the 1991 dry season, when aerial abundance of leafhoppers was small and no infective individuals were recorded.
The allophane studied occurs in the weathered zones of the barite-sulphide-bearing dolomitic levels, interbedded in the barite ore deposits of Vide de Alba and San Bias (Province of Zamora). These ore deposits are interstratified in the Silurian-Devonian sulphide bearing volcano sedimentary materials of the Alcañices Synform. The allophanic samples have been studied by polarizing microscopy, SEM, XRD, DTA, TG, IRS, EMA and chemical analyses, the last after dissolving the samples by acid (HF + HNO3 + 3HCl + H3BO3) and alkaline digestion (0·5 m NaOH). It is suggested that allophane originates from the reaction of acid solutions released during the weathering of sulphides with acid volcanoclastic rocks. Silica-alumina gels were deposited in holes formed during earlier dissolution of the dolomite associated with the barite ores. Later processes of desilication partially transform allophane to gibbsite.