On the Origin of Radial Anisotropy Near Subducted Slabs in the Midmantle

Recent seismic studies indicate the presence of seismic anisotropy near subducted slabs in the transition zone and uppermost lower mantle (mid-mantle). In this study, we investigate the origin of radial anisotropy in the mid-mantle using 3-D geodynamic subduction models combined with mantle fabric simulations. These calculations are compared with seismic tomography images to constrain the range of possible causes of the observed anisotropy. We consider three subduction scenarios: (i) slab stagnation at the bottom of the transition zone; (ii) slab trapped in the uppermost lower mantle; and (iii) slab penetration into the deep lower mantle. For each scenario, we consider a range of parameters, including several slip systems of bridgmanite and its grain-boundary mobility. Modeling of lattice-preferred orientation shows that the upper transition zone is characterized by fast-SV radial anisotropy anomalies up to 121.5%. For the stagnating and trapped slab scenarios, the uppermost lower mantle is characterized by two fast-SH radial anisotropy anomalies of 3c+2% beneath the slab's tip and hinge. On the other hand, the penetrating slab is associated with fast-SH radial anisotropy anomalies of up to 3c+1.3% down to a depth of 2,000\ua0km. Four possible easy slip systems of bridgmanite lead to a good consistency between the mantle modeling and the seismic tomography images: [100](010), [010](100), [001](100), and (Formula presented.). The anisotropy anomalies obtained from shape-preferred orientation calculations do not fit seismic tomography images in the mid-mantle as well as lattice-preferred orientation calculations, especially for slabs penetrating into the deep lower mantle

Aging-related predictive factors for oxygenation improvement and mortality in COVID-19 and acute respiratory distress syndrome (ARDS) patients exposed to prone position: A multicenter cohort study

Background: Elderly patients are more susceptible to Coronavirus Disease-2019 (COVID-19) and are more likely to develop it in severe forms, (e.g., Acute Respiratory Distress Syndrome [ARDS]). Prone positioning is a treatment strategy for severe ARDS; however, its response in the elderly population remains poorly understood. The main objective was to evaluate the predictive response and mortality of elderly patients exposed to prone positioning due to ARDS-COVID-19. Methods: This retrospective multicenter cohort study involved 223 patients aged ≥ 65 years, who received prone position sessions for severe ARDS due to COVID-19, using invasive mechanical ventilation. The PaO2/FiO2 ratio was used to assess the oxygenation response. The 20-point improvement in PaO2/FiO2 after the first prone session was considered for good response. Data were collected from electronic medical records, including demographic data, laboratory/image exams, complications, comorbidities, SAPS III and SOFA scores, use of anticoagulants and vasopressors, ventilator settings, and respiratory system mechanics. Mortality was defined as deaths that occurred until hospital discharge. Results: Most patients were male, with arterial hypertension and diabetes mellitus as the most prevalent comorbidities. The non-responders group had higher SAPS III and SOFA scores, and a higher incidence of complications. There was no difference in mortality rate. A lower SAPS III score was a predictor of oxygenation response, and the male sex was a risk predictor of mortality. Conclusion: The present study suggests the oxygenation response to prone positioning in elderly patients with severe COVID-19-ARDS correlates with the SAPS III score. Furthermore, the male sex is a risk predictor of mortality

Experimental Observation of a New Attenuation Mechanism in <i>hcp</i>‐Metals That May Operate in the Earth's Inner Core

AbstractSeismic observations show the Earth's inner core has significant and unexplained variation in seismic attenuation with position, depth and direction. Interpreting these observations is difficult without knowledge of the visco‐ or anelastic dissipation processes active in iron under inner core conditions. Here, a previously unconsidered attenuation mechanism is observed in zinc, a low pressure analog of hcp‐iron, during small strain sinusoidal deformation experiments. The experiments were performed in a deformation‐DIA combined with X‐radiography, at seismic frequencies (∼0.003–0.1 Hz), high pressure and temperatures up to ∼80% of melting temperature. Significant dissipation (0.077 ≤ Q−1(ω) ≤ 0.488) is observed along with frequency dependent softening of zinc's Young's modulus and an extremely small activation energy for creep (⩽7 kJ mol−1). In addition, during sinusoidal deformation the original microstructure is replaced by one with a reduced dislocation density and small, uniform, grain size. This combination of behavior collectively reflects a mode of deformation called “internal stress superplasticity”; this deformation mechanism is unique to anisotropic materials and activated by cyclic loading generating large internal stresses. Here we observe a new form of internal stress superplasticity, which we name as “elastic strain mismatch superplasticity.” In it the large stresses are caused by the compressional anisotropy. If this mechanism is also active in hcp‐iron and the Earth's inner‐core it will be a contributor to inner‐core observed seismic attenuation and constrain the maximum inner‐core grain‐size to ≲10 km.</jats:p

The anatomy of uppermost mantle shear-wave speed anomalies in the western U.S. from surface-wave amplification

We build SWUS-amp, a three-dimensional shear-wave speed model of the uppermost mantle of the western U.S. using Rayleigh wave amplification measurements in the period range of 35–125 s from teleseismic earthquakes. This represents the first-ever attempt to invert for velocity structures using Rayleigh wave amplification data alone. We use over 350,000 Rayleigh wave amplitude measurements, which are inverted using a Monte Carlo technique including uncertainty quantification. Being a local seismic observable, Rayleigh wave amplification is little affected by path-averaged effects and in principle has stronger depth resolution than classical seismic observables, such as surface wave dispersion data. SWUS-amp confirms shallow mantle heterogeneities found in previous models. In the top 100 km of the mantle, we observe low-velocity anomalies associated with Yellowstone and the Basin & Range province, as well as a fast-velocity anomaly underneath the Colorado Plateau, where a strong velocity gradient at its edges shows a drastic contrast with its surroundings. SWUS-amp also gives additional insights into the current state of the uppermost mantle in the region. We image a high-velocity anomaly beneath the high-topography Wyoming province with a maximum depth extent of about 150–170 km, which is shallower than in previous tomographic models, and resolves previous inconsistencies with geological information. Beneath the Snake River Plain, a finger-like low-velocity anomaly dips to the west, suggesting lateral flow in the region. Below about 150 km depth, SWUS-amp shows a north-south dichotomy in shear-wave speed structure, with the northern region showing mostly high-velocity anomalies, whereas the southern region shows low-velocity anomalies. This is consistent with the continuous subduction history of the western U.S. and with the recent extension and uplift of the southern region

Sistema de suporte à decisão para alocação de água em projetos de irrigação

Neste artigo se apresenta um modelo visando analisar a alocação de água para irrigação, denominado IrrigaLS. Os volumes de água armazenados no solo e nos reservatórios superficiais constituem variáveis de decisão do modelo de rede de fluxo na análise de alocação. O IrrigaLS é um dos programas que integram a base de modelos do sistema de suporte à decisão AcquaNet. As avaliações indicaram que o IrrigaLS foi eficiente para simular sistemas complexos de recursos hídricos sob condição de múltiplos usos, calcular a necessidade hídrica real das culturas e informar garantias de um suprimento mínimo de água para as culturas em períodos de seca. O programa considera a precipitação no balanço hídrico do solo, possibilita variar os volumes meta para armazenamento de água no solo e diferenciar as culturas em relação à sensibilidade ao déficit hídrico. O fato de considerar as interações entre os fatores água, solo, clima e planta, permite uma aproximação melhor para se obter eficiência de uso da água e também melhor estimativa da produção agrícola

Feeding Preference and Performance of Metriona elatior

Boligon, Danessa Schardong, Moreira, Gilson Rudinei Pires (2013): Feeding Preference and Performance ofMetriona elatior(Klug) (Coleoptera: Chrysomelidae), an Oligophagous Cassidine Beetle that Feeds onSolanumL. (Solanaceae) in Southern Brazil. The Coleopterists Bulletin 67 (4): 591-599, DOI: 10.1649/0010-065x-67.4.591, URL: http://dx.doi.org/10.1649/0010-065x-67.4.59

Experimental observation of a new attenuation mechanism in <i>hcp</i>-metals that may operate in the Earth’s Inner Core

Seismic observations show the Earth’s inner core has significant and unexplained variation in seismic attenuation with position, depth and direction. Interpreting these observations is difficult without knowledge of the visco- or anelastic dissipation processes active in hcp-iron in the inner core. Here, a previously unconsidered attenuation mechanism is observed in zinc, a low pressure analogue of hcp-iron, during small strain sinusoidal deformation experiments. The experiments were performed in a deformation-DIA combined with X-radiography, at seismic frequencies (∼0.003–0.1 Hz), high pressure and temperatures up to∼80 % of melting temperature. Significant dissipation (0.077 ≤ Q −1 (ω) ≤ 0.488) is observed along with frequency dependent softening of zinc’s Young’s modulus and an extremely small activation energy forcreep (⩽ 7 kJ mol−1. In addition, during sinusoidal deformation the original microstructure is replaced by one with a reduced dislocation density and small, uniform, grain size. This combination of behaviour collectively reflects a mode of deformation called ‘internal stress superplasticity’; this deformation mechanism is unique to anisotropic materials and activated by cyclic loading generating large internal stresses.  Here we observe a new form of internal stress superplasticity, which we name as ‘elastic strain mismatch superplasticity’. In it the large stresses are caused by the compressional anisotropy. If this mechanism is also active in hcp-iron and the Earth’s inner-core it will be a contributor to inner-core observed seismic attenuation and constrain the maximum inner-core grain-size to ≲ 10 km