Dietary pattern recognition on Twitter: a case example of before,during, and after four natural disasters     

Turner-McGrievy  Gabrielle  Karami  Amir  Monroe  Courtney  Brandt  Heather M. 《Natural Hazards》2020,103(1):1035-1049

Natural Hazards - Little is known about what foods/beverages (F&B) are common during natural disasters. The goal of this study was to track high-frequency F&B mentions during four...  相似文献   

Bathymetric distribution patterns of Southern Ocean macrofaunal taxa: Bivalvia, Gastropoda, Isopoda and Polychaeta     

Angelika Brandt  Katrin Linse  Myriam Schüller   《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):2013-2025

The aim of this study is to compare the depth distributions of four major Southern Ocean macrobenthic epi- and infaunal taxa, the Bivalvia, Gastropoda, Isopoda, and Polychaeta, from subtidal to abyssal depth. All literature data up to summer 2008, as well as the unpublished data from the most recent ANDEEP I–III (Antarctic benthic deep-sea biodiversity: colonisation history and recent community patterns) expeditions to the Southern Ocean deep sea are included in the analysis. Benthic invertebrates in the Southern Ocean are known for their wide bathymetric ranges. We analysed the distributions of four of the most abundant and species-rich taxa from intertidal to abyssal (5200 m) depths in depth zones of 100 m. The depth distributions of three macrofaunal classes (Bivalvia, Gastropoda, Polychaeta) and one order (Isopoda) showed distinct differences. In the case of bivalves, gastropods and polychaetes, the number of species per depth zone decreased from the shelf to the slope at around 1000 m depth and then showed stable low numbers. The isopods showed the opposite trend; they were less species rich in the upper 1000 m but increased in species numbers from the slope to bathyal and abyssal depths. Depth ranges of families of the studied taxa (Bivalvia: 31 families, Gastropoda: 60, Isopoda: 32, and Polychaeta: 46 families) were compiled and illustrated. At present vast areas of the deep sea in the Southern Ocean remain unexplored and species accumulation curves showed that only a fraction of the species have been discovered to date. We anticipate that further investigations will greatly increase the number of species known in the Southern Ocean deep sea.  相似文献   

SHEBA flux–profile relationships in the stable atmospheric boundary layer     

Andrey A. Grachev  Edgar L Andreas  Christopher W. Fairall  Peter S. Guest  P. Ola G. Persson 《Boundary-Layer Meteorology》2007,124(3):315-333

Measurements of atmospheric turbulence made during the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) are used to examine the profile stability functions of momentum, φ _m , and sensible heat, φ _h , in the stably stratified boundary layer over the Arctic pack ice. Turbulent fluxes and mean meteorological data that cover different surface conditions and a wide range of stability conditions were continuously measured and reported hourly at five levels on a 20-m main tower for 11 months. The comprehensive dataset collected during SHEBA allows studying φ _m and φ _h in detail and includes ample data for the very stable case. New parameterizations for φ _m (ζ) and φ _h (ζ) in stable conditions are proposed to describe the SHEBA data; these cover the entire range of the stability parameter ζ = z/L from neutral to very stable conditions, where L is the Obukhov length and z is the measurement height. In the limit of very strong stability, φ _m follows a ζ ^1/3 dependence, whereas φ _h initially increases with increasing ζ, reaches a maximum at ζ ≈ 10, and then tends to level off with increasing ζ. The effects of self-correlation, which occur in plots of φ _m and φ _h versus ζ, are reduced by using an independent bin-averaging method instead of conventional averaging.  相似文献   

Tests of 4 single-stage image intensifier tubes for solar spectroscopy     

Brandt  P. N.  Wiesmeier  A. 《Solar physics》1974,38(2):517-521

Atmospheric image degradation can be reduced by shortening the exposure time. Therefore, four single-stage electrostatically focused image intensifier tubes with fiber optic output were tested in the laboratory for their suitability in solar spectroscopy. Under the premise that the spatial and spectral image scales (Capri: 5.9 mm^–1 and 9 mm Å^–1, resp.) should not be changed by a premagnification, the RCA tube 8605/V1 in combination with Copex Pan Rapid film turns out as the best choice. It yields a resolution of 55 line-pairs mm^–1 and a gain of exposure time by a factor of 14 over Kodak IV-E in the red, with only little increase of photometric noise but appreciable pin-cushion distortion.Mitteilung aus dem Fraunhofer Institut, Nr. 129.  相似文献   

OSO-III: Preliminary scientific results     

John C. Brandt 《Solar physics》1969,6(2):171-174

OSO-III was placed into orbit on March 8, 1967; observations were made of the solar extreme ultraviolet, soft and hard solar X-rays, cosmic X-rays and -rays, cosmic ray particles, and the near-earth optical wavelength radiation environment.  相似文献   

Stable Boundary-Layer Scaling Regimes: The Sheba Data     

Andrey A. Grachev  P. Ola G. Persson  Edgar L. Andreas  Peter S. Guest 《Boundary-Layer Meteorology》2005,116(2):201-235

Turbulent and mean meteorological data collected at five levels on a 20-m tower over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are analyzed to examine different regimes of the stable boundary layer (SBL). Eleven months of measurements during SHEBA cover a wide range of stability conditions, from the weakly unstable regime to very stable stratification. Scaling arguments and our analysis show that the SBL can be classified into four major regimes: (i) surface-layer scaling regime (weakly stable case), (ii) transition regime, (iii) turbulent Ekman layer, and (iv) intermittently turbulent Ekman layer (supercritical stable regime). These four regimes may be considered as the basic states of the traditional SBL. Sometimes these regimes, especially the last two, can be markedly perturbed by gravity waves, detached elevated turbulence (‘upside down SBL’), and inertial oscillations. Traditional Monin–Obukhov similarity theory works well in the weakly stable regime. In the transition regime, Businger–Dyer formulations work if scaling variables are re-defined in terms of local fluxes, although stability function estimates expressed in these terms include more scatter compared to the surface-layer scaling. As stability increases, the near-surface turbulence is affected by the turning effects of the Coriolis force (the turbulent Ekman layer). In this regime, the surface layer, where the turbulence is continuous, may be very shallow (< 5 m). Turbulent transfer near the critical Richardson number is characterized by small but still significant heat flux and negligible stress. The supercritical stable regime, where the Richardson number exceeds a critical value, is associated with collapsed turbulence and the strong influence of the earth’s rotation even near the surface. In the limit of very strong stability, the stress is no longer a primary scaling parameter.  相似文献   

Metamorphic petrology of a high‐T/low‐P granulite terrane (Damara belt,Namibia) – Constraints from pseudosection modelling and high‐precision Lu–Hf garnet‐whole rock dating     

Stefan Jung  Soenke Brandt  Rebecca Bast  Erik E. Scherer  Jasper Berndt 《Journal of Metamorphic Geology》2019,37(1):41-69

Migmatites comprise a minor volume of the high‐grade part of the Damara orogen of Namibia that is dominated by granite complexes and intercalated metasedimentary units. Migmatites of the Southern Central Zone of the Damara orogen consist of melanosomes with garnet+cordierite+biotite+K‐feldspar, and leucosomes, which are sometimes garnet‐ and cordierite‐bearing. Field evidence, petrographic observations, and pseudosection modelling suggest that, in contrast to other areas where intrusion of granitic magmas is more important, in situ partial melting of metasedimentary units was the main migmatite generation processes. Pseudosection modelling and thermobarometric calculations consistently indicate that the peak‐metamorphic grade throughout the area is in the granulite facies (~5 kbar at ~800°C). Cordierite coronas around garnet suggest some decompression from peak‐metamorphic conditions and rare andalusite records late, near‐isobaric cooling to <650°C at low pressures of ~3 kbar. The inferred clockwise P–T path is consistent with minor crustal thickening through continent–continent collision followed by limited post‐collisional exhumation and suggests that the granulite facies terrane of the Southern Central Zone of the Damara orogen formed initially in a metamorphic field gradient of ~35–40°C/km at medium pressures. New high‐precision Lu–Hf garnet‐whole rock dates are 530 ± 13 Ma, 522.0 ± 0.8 Ma, 520.8 ± 3.6 Ma, and 500.3 ± 4.3 Ma for the migmatites that record temperatures of ~800°C. This indicates that high‐grade metamorphism lasted for c. 20–30 Ma, which is compatible with previous estimates using Sm–Nd garnet‐whole rock systematics. In previous studies on Damara orogen migmatites where both Sm–Nd and Lu–Hf chronometers have been applied, the dates (c. 520–510 Ma) agree within their small uncertainties (0.6–0.8% for Sm–Nd and 0.1–0.2% for Lu–Hf). This implies rapid cooling after high‐grade conditions and, by implication, rapid exhumation at that time. The cause of the high geothermal gradient inferred from the metamorphic conditions is unknown but likely requires some extra heat that was probably added by intrusion of magmas from the lithospheric mantle, i.e., syenites that have been recently re‐dated at c. 545 Ma. Some granites derived from the lower crust at c. 545 Ma are the outcome rather than the cause of high‐T metamorphism. In addition, high contents of heat‐producing elements K, Th, and U may have raised peak temperatures by 150–200°C at the base of the crust, resulting in the widespread melting of fertile crustal rocks. The continuous gradation from centimetre‐scale leucosomes to decametre‐scale leucogranite sheets within the high‐grade metamorphic zone suggests that leucosome lenses coalesced to form larger bodies of anatectic leucogranites, thereby documenting a link between high‐grade regional metamorphism and Pan‐African magmatism. In view of the close association of the studied high‐T migmatites with hundreds of synmetamorphic high‐T granites that invaded the terrane as metre‐ to decametre‐wide sills and dykes, we postulate that crystallization of felsic lower crustal magma is, at least partly, responsible for heat supply. Late‐stage isobaric cooling of these granites may explain the occurrence of andalusite in some samples.  相似文献   

The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary Layer   总被引：7，自引：7，他引：0  

Andrey A. Grachev  Edgar L Andreas  Christopher W. Fairall  Peter S. Guest  P. Ola G. Persson 《Boundary-Layer Meteorology》2013,147(1):51-82

Measurements of atmospheric turbulence made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to determine the limits of applicability of Monin–Obukhov similarity theory (in the local scaling formulation) in the stable atmospheric boundary layer. Based on the spectral analysis of wind velocity and air temperature fluctuations, it is shown that, when both the gradient Richardson number, Ri, and the flux Richardson number, Rf, exceed a ‘critical value’ of about 0.20–0.25, the inertial subrange associated with the Richardson–Kolmogorov cascade dies out and vertical turbulent fluxes become small. Some small-scale turbulence survives even in this supercritical regime, but this is non-Kolmogorov turbulence, and it decays rapidly with further increasing stability. Similarity theory is based on the turbulent fluxes in the high-frequency part of the spectra that are associated with energy-containing/flux-carrying eddies. Spectral densities in this high-frequency band diminish as the Richardson–Kolmogorov energy cascade weakens; therefore, the applicability of local Monin–Obukhov similarity theory in stable conditions is limited by the inequalities Ri < Ri _cr and Rf < Rf _cr. However, it is found that Rf _cr  =  0.20–0.25 is a primary threshold for applicability. Applying this prerequisite shows that the data follow classical Monin–Obukhov local z-less predictions after the irrelevant cases (turbulence without the Richardson–Kolmogorov cascade) have been filtered out.  相似文献   

An intense soft excess and evidence for light bending in the luminous narrow-line quasar PHL 1092     

L. C. Gallo  Th. Boller  W. N. Brandt  A. C. Fabian  D. Grupe 《Monthly notices of the Royal Astronomical Society》2004,352(3):744-752

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The X-ray variability of the narrow-line type 1 Seyfert galaxy IRAS 13224–3809 from an XMM–Newton observation     

L. C. Gallo  Th. Boller  Y. Tanaka  A. C. Fabian  W. N. Brandt  W. F. Welsh  N. Anabuki  Y. Haba 《Monthly notices of the Royal Astronomical Society》2004,347(1):269-276

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