Interband electron Raman scattering in a quantum wire in a transverse magnetic field

Electron Raman scattering (ERS) is investigated in a parabolic semiconductor quantum wire in a transverse magnetic field neglecting by phonon-assisted transitions. The ERS cross-section is calculated as a function of a frequency shift and magnetic field. The process involves an interband electronic transition and an intraband transition between quantized subbands. We analyze the differential cross-section for different scattering configurations. We study selection rules for the processes. Some singularities in the Raman spectra are found and interpreted. The scattering spectrum shows density-of-states peaks and interband matrix elements maximums and a strong resonance when scattered frequency equals to the "hybrid" frequency or confinement frequency depending on the light polarization. Numerical results are presented for a GaAs/AlGaAs quantum wire.Comment: 8 pages, 5 figure

Sobre el Jurásico del Mencal y su relación con otras series sub-béticas de la transversal de Granada

Se describen nuevos términos pertenecientes a la serie jurásica del Mencal (Morrón de la Meseta), junto con otros de un corte próximo a Iznalloz (Granada). Ambas series se correlacionan entre si y con otras series que constituyen un umbral en la cuenca sedimentaria subbética

Planktonic Chlorophyceae from the lower Ebro River (Spain)

On samples obtained in 4 seasonal periods between April 1999 and February 2000 from the last 18 km of Ebro River (Spain) some interesting planktonic coccal green algae (Chlorophyceae) were found. This paper offers comments and taxonomical observations on 60 taxa. Crucigenia smithii (Kirchner) W. et G. S. West, Crucigeniella pulchra (W. et G.S.West) Komárek, Elakatothrix genevensis (Reverdin) Hindák, E. subacuta Koršikov, Nephrocytium schilleri (Kammerer) Comas, Oocystidium ovale Kor{ikov, Pseudoschroederia antillarum (Komárek) Hegewald et Schnepf, Scenedesmus denticulatus var. fenestratus (Teiling) Uherkovich, S. pannonicus Hortobágyi, Siderocelis ornata (Fott) Fott, Tetrachlorella alternans (G.M. Smith) Koršikov and Tetrastrum komarekii Hindák were found for the first time in this country. The best represented genus was Scenedesmus, with 16 taxa

Sobre el Jurásico del Mencal y su relación con otras series sub-béticas de la transversal de Granada

Se describen nuevos términos pertenecientes a la serie jurásica del Mencal (Morrón de la Meseta), junto con otros de un corte próximo a Iznalloz (Granada). Ambas series se correlacionan entre si y con otras series que constituyen un umbral en la cuenca sedimentaria subbética

Decomposition of homogeneous polynomials with low rank

Let $F$ be a homogeneous polynomial of degree $d$ in $m+1$ variables defined over an algebraically closed field of characteristic zero and suppose that $F$ belongs to the $s$-th secant varieties of the standard Veronese variety $X_{m,d}\subset \mathbb{P}^{{m+d\choose d}-1}$ but that its minimal decomposition as a sum of $d$-th powers of linear forms $M_1, ..., M_r$ is $F=M_1^d+... + M_r^d$ with $r>s$. We show that if $s+r\leq 2d+1$ then such a decomposition of $F$ can be split in two parts: one of them is made by linear forms that can be written using only two variables, the other part is uniquely determined once one has fixed the first part. We also obtain a uniqueness theorem for the minimal decomposition of $F$ if the rank is at most $d$ and a mild condition is satisfied.Comment: final version. Math. Z. (to appear

Improved retrieval of nitrogen dioxide (NO2) column densities by means of MKIV Brewer spectrophotometers

A new algorithm to retrieve nitrogen dioxide (NO2) column densities using MKIV ("Mark IV") Brewer spectrophotometers is described. The method includes several improvements, such as a more recent spectroscopic data set, the reduction of measurement noise, interference by other atmospheric species and instrumental settings, and a better determination of the zenith sky air mass factor. The technique was tested during an ad hoc calibration campaign at the high-altitude site of Izaña (Tenerife, Spain) and the results of the direct sun and zenith sky geometries were compared to those obtained by two reference instruments from the Network for the Detection of Atmospheric Composition Change (NDACC): a Fourier Transform Infrared Radiometer (FTIR) and an advanced visible spectrograph (RASAS-II) based on the differential optical absorption spectrometry (DOAS) technique

Position paper - progress towards standards in integrated (aerobic) MBR modelling

Membrane bioreactor (MBR) models are useful tools for both design and management. The system complexity is high due to the involved number of processes which can be clustered in biological and physical ones. Literature studies are present and need to be harmonized in order to gain insights from the different studies and allow system optimization by applying a control. This position paper aims at defining the current state of the art of the main integrated MBR models reported in the literature. On the basis of a modelling review, a standardized terminology is proposed to facilitate the further development and comparison of integrated membrane fouling models for aerobic MBRs

Sedimentological and palaeohydrological characterization of Late Pleistocene and Holocene tufa mound palaeolakes using trenching methods in the Spanish Pyrenees

Lakes developed in the inner depressions of tufa mounds are rare geomorphic features and still poorly understood. Sedimentation in this unusual type of endorheic lake with a very restricted catchment area is highly sensitive to environmental and hydrological changes. The Isona tufa mound complex, north-eastern Iberian Peninsula, is associated with the discharge zone of a confined artesian aquifer and comprises 11 tufa mounds consisting of an annular rimstone enclosing a central depression filled with lake deposits. Data gathered from trenches excavated in four palaeolakes located within three different morphostratigraphic units permitted a precise analysis of the geometrical characteristics and stratigraphic relationships of the deposits and provided a sedimentation model for the Late Quaternary infilling of the spring-fed lakes. The work illustrates that trenches allow a precise characterization of the stratigraphic arrangements, lateral facies changes and deformation structures, which are not apparent in studies relying solely on borehole records, and facilitate sampling for dating and geochemical analyses. The five sedimentary facies described represent different evolutionary stages of the lakes, including: (i) carbonate-rich palustrine deposits probably related to periods with strong hydrological seasonality; (ii) massive highly bioturbated organic ooze; (iii) banded organic carbonate-rich facies associated with an increase in the regional effective moisture; (iv) finegrained quartz-rich aeolian/slope-wash sediments; and (v) colluvial facies deposited following the desiccation of the lakes located at higher altitudes. Geochemical and sedimentological analyses of the lacustrine sequences provided information on the palaeohydrological evolution of the Isona tufa mound complex and the palaeoenvironmental conditions of the area over the last 28 ka. Radiometric dating suggests that deposition occurred simultaneously at ca 22 ka in palaeolakes situated at different elevations. A drop in the piezometric level prompted by the opening of springs at lower altitudes probably caused the deactivation of the upper springs and the desiccation of the lakes. Arid conditions prevailed in the area during the Late Glacial and the early Holocene (28·0 to 8·5 ka BP). More humid conditions recorded from 8·5 to 4·2 ka and again since 1·7 ka are in accordance with palaeoenvironmental reconstructions available in the Western Mediterranean since the Last Glacial Maximum

Identifying the boundaries of sinkholes and subsidence areas via trenching and establishing setback distances

One of the most effective mitigation strategies in sinkhole areas is the exclusion of sinkholes and their vicinity to construction. The application of this preventive measure requires precise mapping of the boundaries of the areas affected by subsidence and the establishment of adequate setback distances, which is an important policy issue with significant economic implications. Through the investigation of several buried sinkholes in the mantled evaporite karst of the Ebro Valley by trenching, this work illustrates that the actual extent of the subsidence areas may be much larger than that inferred from surface mapping and geophysical surveys. The objective and accurate subsurface information acquired from trenches on the outer edge of the deformed ground revealed sinkhole radii 2–3 times larger than initially estimated, increasing one order of magnitude the sinkhole area. Trenches can therefore help to reduce mapping uncertainties and the size of setbacks. Moreover, the trenching technique, in combination with geochronological data and retrodeformation analyses, provides critical information on the subsidence phenomena and the characteristics of the sinkholes relevant to hazard assessment. Since recommended setback distances found in the existing literature are highly variable and rather arbitrary, we include a discussion here on the main factors that should be considered when defining setback zones for sinkholes

Rasgos de personalidad y burnout en médicos de familia

ObjetivoInvestigar los rasgos de personalidad que podrían asociarse con puntuaciones altas en las escalas de burnout (Maslach Burnout Inventory) en médicos de atención primaria.DiseñoEstudio observacional, descriptivo, transversal.EmplazamientoNoventa y tres centros de atención primaria de la ciudad de Barcelona y las comarcas del norte de la provincia: Vallès Oriental, Vallès Occidental, Maresme, Osona, Bages y Berguedà (región sanitaria centro).MétodoEncuesta directa por entrevista personal o grupal a 528 médicos de atención primaria. Se administraron 3 cuestionarios: uno de datos sociodemográficos generales, el Maslasch Burnout Inventory (MBI) y el test de personalidad de Cattell 16 PF-5.ResultadosUn 40% de los encuestados presentaba algún síntoma de burnout sin diferencia entre sexos. De éstos, un 12,4% manifestaba niveles muy altos de «quemazón» profesional. Los sujetos con criterios de burnout obtuvieron puntuaciones significativamente diferentes en los rasgos de estabilidad, tensión y vigilancia y en la dimensión ansiedad.ConclusionesAlgunos rasgos de personalidad, como la baja estabilidad emocional, la tensión y la ansiedad, se asocian de manera significativa a puntuaciones altas de burnoutExisten algunas diferencias entre estos factores internos por sexo.ObjectiveWith this research we try to study personality traits that could be associated with high punctuation at burnout scales (Maslach Burnout Inventory) in primary care physicians.DesignObservational descriptive transversal studySetting93 primary care centres in Barcelona-city and the northern province's region: Vallès Oriental, Vallès Occidental, Maresme, Osona, Bages and Berguedà (centre sanitary region).MethodIndividual or collective direct interview to 528 primary care physicians. Three questioners were administrated: a sociodemographyc items one, the Maslach Burnout Inventory (MBI) and the Cattell personality test 16-PF.ResultsThe 40% of the interviewed physicians had some burnout symptom without any difference between sexes. The 12.4% of these ones showed very high burnout levels. Those subjects with burnout criteria punctuated different at stability, tension and vigilance traits and anxiety dimension.ConclusionSome personality traits like low stability, the tension and the anxiety are associated with high punctuation of burnout