12,927 research outputs found
A Measurement of Secondary Cosmic Microwave Background Anisotropies with Two Years of South Pole Telescope Observations
We present the first three-frequency South Pole Telescope (SPT) cosmic microwave background (CMB) power spectra. The band powers presented here cover angular scales 2000 < ℓ < 9400 in frequency bands centered at 95, 150, and 220 GHz. At these frequencies and angular scales, a combination of the primary CMB anisotropy, thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB) contributes to the signal. We combine Planck/HFI and SPT data at 220 GHz to constrain the amplitude and shape of the CIB power spectrum and find strong evidence for nonlinear clustering. We explore the SZ results using a variety of cosmological models for the CMB and CIB anisotropies and find them to be robust with one exception: allowing for spatial correlations between the thermal SZ effect and CIB significantly degrades the SZ constraints. Neglecting this potential correlation, we find the thermal SZ power at 150 GHz and ℓ = 3000 to be 3.65 ± 0.69 μK^2, and set an upper limit on the kinetic SZ power to be less than 2.8 μK^2 at 95% confidence. When a correlation between the thermal SZ and CIB is allowed, we constrain a linear combination of thermal and kinetic SZ power: D^(tSZ)_(3000) + 0.5D^(kSZ)_(3000) = 4.60 ± 0.63 μK^2, consistent with earlier measurements. We use the measured thermal SZ power and an analytic, thermal SZ model calibrated with simulations to determine σ_8 = 0.807 ± 0.016. Modeling uncertainties involving the astrophysics of the intracluster medium rather than the statistical uncertainty in the measured band powers are the dominant source of uncertainty on σ_8. We also place an upper limit on the kinetic SZ power produced by patchy reionization; a companion paper uses these limits to constrain the reionization history of the universe
Application of Delft3d for designing and assessing new solutions to improve sediment input to an erosion prone coast
The construction of harbor defense structures changes the natural sedimentary fluxes that contribute to feed the coastal drift in the adjacent beaches, in many harbors of the world located at river mouths. This paper presents a numerical modelling work, based on the Delft3D software, to study morphodynamics at the river Lima estuary, Portugal. This model was implemented recurring to a hydroinformatic environment that was constructed at University of Minho along the last two decades. Considering specific hydrodynamic conditions and typical characteristics of the estuarine sediments, the capacity of hypothetical structures to improve transport of sediments to the coast was assessed: (i) a submerged transverse non-erodible dam and (ii) an emerged groin linked to the left embankment located at the upstream section of the harbor. The implemented hydroinformatic environment presents capacities to simulate the complex morphodynamic behavior of river mouths. The preliminary results reveals that the proposed structures can have a positive impact throughout dredging works facilitation by transferring depositional areas during flood events to a location near the coast inside the harbor. Ongoing field acquisition data will be essential to validate depositional patterns under different river discharges and wave conditionsPOCTEP/Interreg, project MarRISK (0262_MarRISK_1_E)info:eu-repo/semantics/publishedVersio
Runoff at the micro-plot and slope scale following wildfire, central Portugal
Through their effects on soil properties and vegetation/litter cover, wildfires can strongly enhance overland flow generation and accelerate soil erosion [1] and, thereby, negatively affect land-use sustainability as well as downstream aquatic and flood zones. Wildfires are a common phenomenon in present-day Portugal, devastating in an average year some 100.000 ha of forest and woodlands and in an exceptional year like 2003 over 400.000 ha. There therefore exists a clear need in Portugal for a tool that can provide guidance to post-fire land management by predicting soil erosion risk, on the one hand, and, on the other, the mitigation effectiveness of soil conservation measures. Such a tool has recently been developed for the Western U.S.A. [3: ERMiT] but its suitability for Portuguese forests will need to be corroborated by field observations.
Testing the suitability of existing erosion models in recently burned forest areas in Portugal is, in a nutshell, the aim of the EROSFIRE projects. In the first EROSFIRE project the emphasis was on the prediction of erosion at the scale of individual hill slopes. In the ongoing EROSFIRE-II project the spatial scope is extended to include the catchment scale, so that also the connectivity between hill slopes as well as channel and road processes are being addressed. Besides ERMiT, the principal models under evaluation for slope-scale erosion prediction are: (i) the variant of USLE [4] applied by the Portuguese Water Institute after the wildfires of 2003; (ii) the Morgan–Morgan–Finney model (MMF) [5]; (iii) MEFIDIS [6]. From these models, MEFIDIS and perhaps MMF will, after successful calibration at the slope scale, also be applied for predicting catchment-scale sediment yields of extreme events
Assessing the extent of occurrence, area of occupancy, territory size, and population size of marsh tapaculo (Scytalopus iraiensis)
Evaluación de la extensión de presencia, la superficie de ocupación, el tamaño del territorio y el tamaño de la población del churrín palustre (Scytalopus iraiensis)
Descrito por primera vez en 1998, el churrín palustre (Scytalopus iraiensis) es un ave en peligro de extinción de la familia Rhinocryptidae. Es endémica de Brasil y su presencia queda restringida a los planos aluviales de los ríos y los cursos de agua. Debido a sus hábitos crípticos y a los ambientes en los que se halla presente, la información disponible sobre su biología, su historia natural y su distribución es escasa. Compilamos varios registros de presencia (99 registros), delimitamos la extensión
de las presencias (296.584 km2), calculamos la superficie de ocupación (84 km2) y estimamos el tamaño del territorio (5.313 ± 1.201 m2 por pareja), la densidad de la población (3,76 ± 0,85 individuos por hectárea) y el tamaño de la población (31.584 ± 7.140 individuos maduros) del churrín palustre. La especie se registró en zonas de marismas asociada a cuatro tipos de vegetación y en cuatro zonas ecológicas. Esta nueva información es fundamental para respaldar la reevaluación de la categoría de situación de peligro de la especie y potenciar el conocimiento de esta ave endémica y poco conocida de Brasil
A Comprehensive View of a Strongly Lensed Planck-Associated Submillimeter Galaxy
We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9–001132 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 μm flux density (~300 mJy). It is the only high-redshift Planck detection in the 130 deg^2 H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 μm and CO(1→0) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over ~1.6 kpc, the dust in a compact (~1 kpc) region ~3 kpc north of the stars, and the cold molecular gas in an extended (~7 kpc) disk ~5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by ~17, ~8, and ~7 times, respectively, by four lensing galaxies at z ~ 1. Intrinsically, the lensed galaxy is a warm (T_(dust) ~ 40-65 K), hyper-luminous (L_(IR) ~ 1.7 × 10^(13) L_☉; star formation rate (SFR) ~2000 M_☉ yr^(–1)), gas-rich (M_(gas)/M_(baryon) ~ 70%), young (M_(stellar)/SFR ~ 20 Myr), and short-lived (M_(gas)/SFR ~ 40 Myr) starburst. With physical properties similar to unlensed z > 2 SMGs, HATLAS J114637.9–001132 offers a detailed view of a typical SMG through a powerful cosmic microscope
Aspectos da aplicação do Delft Hydraulics 'SOBEK' no desenvolvimento de um sistema de gestão operacional da água em Alqueva
No âmbito do desenvolvimento de um Sistema de Suporte à Decisão (SSD) para a gestão da
água no Empreendimento de Fins Múltiplos de Alqueva (EFMA) foi seleccionado, após uma avaliação de diferentes alternativas de software de modelação hidrodinâmica e de qualidade da água, o
programa SOBEK (WL, 2005) para a modelação de problemas de qualidade da água unidimensionais.
No presente trabalho apresentam-se as características mais importantes deste programa e descrevem-se os principais aspectos relacionados com a sua integração no ambiente hidroinformático em desenvolvimento para a gestão operacional das infra-estruturas, construídas e em fase de projecto, da rede primária do Subsistema de Alqueva a montante da barragem de Alvito.
A construção do modelo hidrodinâmico foi precedida de um estudo pormenorizado das infraestruturas que constituem o sistema em análise, com recurso a informação constante dos seus projectos de execução. A caracterização geométrica das infra-estruturas foi desenvolvida com o detalhe correspondente ao de projecto de execução (ou levantamento no caso de infra-estruturas existentes), distinguindo-se duas situações físicas distintas: albufeiras e sistemas adutores. No casodas albufeiras consideraram-se os seguintes elementos de projecto: fundo ou topografia do terreno; planta correspondente aos níveis relevantes; cortes; características das barragens; descarga de fundo e de caudal ecológico; descarregadores intermédios; descarregadores de cheia. No caso dos canais,
túneis e condutas em pressão consideraram-se os seguintes elementos de projecto: planta com
traçado do eixo; perfil longitudinal; secções transversais e acessórios
Pressure induced effects on the Fermi surface of superconducting 2H-NbSe
The pressure dependence of the critical temperature and upper critical
field has been measured up to 19 GPa in the layered superconducting
material 2H-NbSe. Relating the behavior of to Fermi surface
parameters, we find that the electron phonon coupling of the 2D Nb 4d derived
bands shows a peak at 5 GPa when the charge density wave (CDW) order is
suppressed. On the other hand, shows a bell shaped curve with a
maximum at 10.5 GPa, well above the pressure for the suppression of the CDW
order. Changes in the band structure produce this shift in the maximum of
, demonstrating that 2H-NbSe shows important differences with
respect to other compounds where has a maximum in the temperature-density
phase diagram shaped by the suppression of another, non-superconducting, ground
state.Comment: 5 pages, 4 figures. Small changes in discussion. Typos correcte
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