Miracle-dz/UniFAR-FTUs huggingface dataset:
Palaeovegetational and palaeoenvironmental trends in the summit of the Guaiquinima massif (Venezuelan Guayana) during the Holocene

The summits of the table mountains (tepuis) from the Neotropical Guayana region are remote environments suitable for palaeoecological studies with evolutionary, biogeographical and palaeoclimatic implications. Here, using palynological analyses of two radiocarbon‐dated peat bogs from a tepui summit, the Holocene palaeovegetational trends are reconstructed, and related to possible forcing factors. Because of the pristine character of the Guaiquinima summit, the recorded palaeoenvironmental changes are probably due to natural causes, which makes them valuable archives of the natural component of climatic change at a millennial time scale. The sequence begins with pioneer communities or meadows similar to present‐day ones, between about 8.4 and 4.5 ky BP. After this date, and until about 2 kyr BP the expansion of gallery forests suggests an increase in precipitation, documented also at regional (Neotropical) level. Between ca. 2 kyr BP and the last century, gallery forests are replaced by forests characteristic of the upper Guaiquinima altitudes, coinciding with a regional phase of reduced moisture. The present‐day meadows, established relatively quickly during the last century, substituted the former upland forests. In the locality studied, the main controlling factor of the vegetation during the Holocene seems to have been the moisture balance. In contrast to other tepui summits, there is no clear evidence for changes linked to temperature oscillations. This could be due to the elevation of the site, far from any characteristic ecological boundary, that makes it insensitive to this parameter. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical evaluation of the transient acoustic waveform due to a point source in a fluid-filled borehole

A key measurement employed in oil well wireline logging is the acoustic wave traveltime over a specified formation interval, typically 1 ft. In the traditional measurement, only the compressional head wave is monitored, but for some time it has been obvious that there is significant additional information, such as the shear head wave arrival, in the received waveform. We describe two numerical methods for computing the profile and parameter dependence of the transient waveform based on a model of the acoustic logging problem consisting of a point source on the axis of a fluid‐filled cylindrical borehole. The response to this excitation is determined at a distance from the source, generally on the borehole axis. In the first of the two numerical methods, called “real axis integration”, the complete acoustic waveform is obtained. The second method, called “branch‐cut integration”, evaluates the first compressional and shear‐pseudo‐Rayleigh arrivals individually with much less computation time than the first.
Depolarization ratio–effective lidar ratio relation: Theoretical basis for space lidar cloud phase discrimination

This paper introduces a technique for cloud phase discrimination based on linear polarization measurements made by space‐based lidar. Using CALIPSO Level 2 data products, a 3‐dimensional histogram of the depolarization ratio, δ, and the effective lidar ratio, Sc,eff, is derived for all optically thick clouds measured during July 2006. A second histogram is derived using data from early November, 2006. By analysis of the relationship between δ and Sc,eff, and an examination of their spatial correlations, water clouds, ice clouds with randomly oriented particles and ice clouds with horizontally oriented particles are clearly differentiated. For clouds having the same depolarization ratios, the effective lidar ratios of water clouds are significantly smaller than the effective lidar ratios of ice clouds comprised of randomly oriented particles. The variance of the depolarization ratios within water clouds is significantly larger than it is in ice clouds containing horizontally oriented particles. Depolarization ratios and effective lidar ratios are negatively correlated for water clouds, and positively correlated for ice clouds with horizontally‐oriented particles. For the optically thick ice clouds observed by CALIPSO, approximately half contain some fraction (up to 100%) of horizontally oriented particles.
RRS James Cook Cruise 36, 19 Jul-28 Jul 2009. The Geobiology of Whittard Submarine Canyon

The biological and geological research programme for James Cook cruise 36 was built around a series of ROV video transects to determine variations in species and community structure and composition in different geological and topographic settings down the canyon. ROV transects were planned to undertake detailed studies of recognised biological hotspots on both hard and soft substrates, to collect specimens for taxonomic studies, including molecular genetics, and to carry out biological experiments, including the use of in situ incubation chambers and tracer feeding experiments to study the physiology of deep-water fauna. Additional coring, CTD and water column particulate sampling programmes were planned to investigate the recent geological history of the canyon, and, in particular, to investigate whether significant sediment is currently accumulating in any part of the canyon, to sample macro- and meiofauna in areas of soft substrate, and to investigate the fate of organic carbon in the canyon. JC36 was highly successful. The cruise built on the successful mapping of the canyon, using swath bathymetry and 30 kHz sidescan sonar, undertaken during JC35. The main achievements of JC36 included the completion of 26 ROV dives, totalling 340 hr. Seafloor video and photographs along 12 transects from the eastern and western canyon branches between 500 and 3600 m waterdepth were collected. A collection of over 240 biological specimens was collected to verify species identification from the video transects. Pushcores for sedimentology, organic geochemistry, biology and microbiology were also collected. Ultra high-resolution swath bathymetry of the canyon floor using the multibeam system mounted on the ROV was collected on 8 dives. A total of 10 dives were dedicated to placing, initiating and recovering a variety of biological experiments on the seafloor, mainly to examine respiration rates of individual animals or animal communities. The coring programme completed 19 successful piston core stations and 29 successful megacore stations. Most of the latter were processed for macrofauna and meiofauna but some were subsampled for sedimentology and geochemistry. A preliminary assessment suggests that most of the sediment recovered is late glacial in age, and that little Holocene sediment has been deposited in the canyon. 6 CTD profiles and 5 SAPS (stand-alone pump) stations were completed to characterise the suspended particulate matter above the canyon floor. A total of 30 pushcores and megacores also sampled for organic geochemistry.
Influence of tides and tidal current on Mertz Glacier, Antarctica

Abstract Mertz Glacier, East Antarctica, is characterized by a 140 km long, 25 km wide floating ice tongue. In this paper, we combine a large number of remotely sensed datasets, including in situ global positioning system measurements, satellite radar altimetry, airborne radio-echo sounding and satellite synthetic aperture radar imagery and interferometry. These various datasets allow us to study the interaction of the ice tongue with the tides and currents. However, the inverse barometer effect needs to be applied to sea-level variations affecting the tongue. We find that the tide-induced currents exert a small lateral pressure on the tongue which, when integrated over the large surface of the tongue, induce a flexure of up to 2 m amplitude per day. Simple elastic modelling of the flexure confirms the observations and helps validate the boundary conditions necessary to explain different eastward and westward tongue deflections. In addition, the along-flow velocity of the tongue does vary daily from 1.9 to 6.8 md-1 depending on the tidal current. When the current pushes the tongue toward the eastern boundary of the fjord, the tongue is retarded by the drag and the velocity decreases. The accumulated stress is released, allowing the tongue to flow very rapidly when the current pushes the tongue westward. These forcing and boundary conditions on the floating ice flow are important and must be taken into account when studying glacier discharge and calving.
Late-Twentieth-Century Simulation of Arctic Sea Ice and Ocean Properties in the CCSM4

AbstractTo establish how well the new Community Climate System Model, version 4 (CCSM4) simulates the properties of the Arctic sea ice and ocean, results from six CCSM4 twentieth-century ensemble simulations are compared here with the available data. It is found that the CCSM4 simulations capture most of the important climatological features of the Arctic sea ice and ocean state well, among them the sea ice thickness distribution, fraction of multiyear sea ice, and sea ice edge. The strongest bias exists in the simulated spring-to-fall sea ice motion field, the location of the Beaufort Gyre, and the temperature of the deep Arctic Ocean (below 250 m), which are caused by deficiencies in the simulation of the Arctic sea level pressure field and the lack of deep-water formation on the Arctic shelves. The observed decrease in the sea ice extent and the multiyear ice cover is well captured by the CCSM4. It is important to note, however, that the temporal evolution of the simulated Arctic sea ice cover over the.
First RHESSI terrestrial gamma ray flash catalog

[1] We present a summary of data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) terrestrial gamma ray flash (TGF) catalog. We describe the RHESSI search algorithm and discuss its limitations due to its design emphasis on cleanliness rather than completeness. This search algorithm has identified 820 TGFs between March of 2002 and February of 2008. Radiation damage to the RHESSI detectors has resulted in a decreased sensitivity after early 2006 and a corresponding decrease in the number of identified TGFs in the years 2006–2008. Prior to this, the average rate of occurrence was one TGF every 2.35 days. RHESSI has seen multiple TGFs associated with a single storm system, either in the same orbit or in the subsequent orbit. The X-ray flux in a 100 ms pedestal region surrounding all of the TGFs is (1.3 ± 1.9) × 10−3 times the average peak flux of a TGF. We show that RHESSI was counting at or near its maximum throughput during the peak 50 μs of many of the TGFs and that we do not yet know the maximum possible brightness of a TGF. On short time scales, some TGFs may be much brighter than could be observed by either RHESSI or BATSE. Finally, we show that there is no detectable change in the spectrum of TGFs when they are grouped by brightness, geographic latitude, geomagnetic latitude, or the local day or night.
Does Time Zone Proximity Matter for Brazil? A Study of the Brazilian I.T. Industry

Nations now compete in their time zone position. Indian IT has long positioned itself as ideal in time zone geography: we get the work done while you're sleeping! So, since the beginning of this decade the Brazilian IT industry, in order to differentiate from India, has proclaimed: we are accessible and easy to work with because we're working while you're working. 38% of Brazilian firms boast about time zone location in their marketing literature – as does the industry association Brasscom.This report is written for decision makers inside and outside Brazil who are examining their global collaboration issues in the IT services/offshoring/software industry. Brazilian decision makers can learn how to better utilize their time zone proximity. Decision makers in North America and Europe can learn how to better utilize their Brazilian partners. Note that nearly all managerial implications in this report apply to any Latin American nation.This report is focused on coordination across time zones. While there are many other challenges working across borders, such as culture and language, the focus here is solely on time zones. Atualmente, os paises tem utilizado suas posicoes geograficas como diferencial competitivo. O mercado indiano de TI, por exemplo, tem se posicionado ha um bom tempo como um pais ideal em termos de fuso-horario: nos trabalhamos enquanto voce esta dormindo! Neste sentido, a partir do inicio desta decada a industria brasileira de TI, de forma a se diferenciar da India, declarou: nos somos acessiveis e mais faceis para trabalhar por que nos trabalhamos enquanto voce trabalha! 38% das empresas brasileiras utilizam a proximidade de fuso-horario como uma vantagem no seu material de divulgacao – assim como a Brasscom, uma entidade que reune diversas empresas de TI, nacionais e multinacionais, alem de centros de pesquisa e Universidades, representando 70% do PIB brasileiro de TI. Este relatorio foi escrito para tomadores de decisao dentro e fora do Brasil e que estao analisando seus desafios de colaboracao global na industria de software e servicos de TI. Os tomadores de decisao brasileiros podem aprender sobre como utilizar sua proximidade de fuso-horario. Ja os tomadores de decisao na America do Norte e Europa podem aprender sobre como interagir melhor com seus parceiros brasileiros. Cabe destacar que grande parte das implicacoes gerenciais neste relatorio se aplica para qualquer pais da America Latina. Este relatorio e focado na coordenacao em diferentes fusos-horario. Apesar de existirem diversos outros desafios ao se trabalhar de forma distribuida e global, tais como cultura e idioma, o foco aqui e somente no fuso-horario.
Neural Networks for Rainfall Forecasting by Atmospheric Downscaling

Several studies have used artificial neural networks (NNs) to estimate local or regional precipitation/rainfall on the basis of relationships with coarse-resolution atmospheric variables. None of these experiments satisfactorily reproduced temporal intermittency and variability in rainfall. We attempt to improve performance by using two approaches: (1) couple two NNs in series, the first to determine rainfall occurrence, and the second to determine rainfall intensity during rainy periods; and (2) categorize rainfall into intensity categories and train the NN to reproduce these rather than the actual intensities. The experiments focused on estimating 12-h mean rainfall in the Chikugo River basin, Kyushu Island, southern Japan, from large-scale values of wind speeds at 850 hPa and precipitable water. The results indicated that (1) two NNs in series may greatly improve the reproduction of intermittency; (2) longer data series are required to reproduce variability; (3) intensity categorization may be useful for probabilistic forecasting; and (4) overall performance in this region is better during winter and spring than during summer and autumn.
Variação espacial do grau de trofia e da biomassa fitoplanctônica no reservatório de Itupararanga (São Paulo, Brasil)

Nowadays the Brazilian reservoirs has suffered great pressure due to increasing demand for water for diverse purposes, being one of the largest eutrophication problems caused by man. The Itupararanga reservoir provides environmental services to more than one million people and is one of the main sources of the Sorocaba River basin and middle Tiete. Thus this study aimed to determine the spatial variability of the trophic level and phytoplankton biomass in the reservoir, as well as the concentrations of nutrients and also check your environment according to CONAMA 357/2005 (BRASIL, 2005). For this, a collection that was conducted in six sampling stations and the measures of pH, conductivity, dissolved oxygen, water temperature, water transparency, total phosphorus, total phosphorus, dissolved nitrite, nitrate, chlorophyll-a and sediment size analysis . The results indicated that there was no spatial variation of the degree of trophy in the Itupararanga reservoir, but there was spatial variation of nutrient concentrations and chlorophyll-a, corroborating theoretical models of reservoir compartmentalization.
Incorporation of Subducted Slab-derived Sediment and Fluid in Arc Magmas: B–Be–10Be–εNd Systematics of the Kurile Convergent Margin, Russia

We present an investigation of B^Be^Be^eNd systematics of the incoming crust and across the wide, active Kurile arc in the NW Pacific ocean basin to address the role of recent sediment incorporation in arc magmas as a function of depth to the Wadati^Benioff zone. The Be flux ratio (8^14%) through the arc constrains the fate of sediments subducted at the trench and requires that a minimum ! 10 m of the sediment column must reach the depths of magma generation. Enrichments in subducted sediment-derived Be in rear-arc lavas are comparable with those in the volcanic front, despite longer subduction transit times, and require a mechanism for the prolonged release of Be from the subducting slab. Cross-arc Be enrichments, together with drastic reductions in B/Be, imply a protracted stability of their primary mineralogical host in subducted sediment, white mica (phengite). The persistence of phengite constrains slab surface temperatures to be 59508C to 165 km depth and limits the extent of partial melting of the slab to520%. The simplest interpretation of combined incoming sediment and cross-arc B/Be^Be/Be^eNd systematics is that the agent of element transfer changes from aqueous fluid-dominated beneath the volcanic front to melt-like beneath the deeper regions of the arc.
Disjunct eddy covariance measurements of oxygenated volatile organic compounds fluxes from an alfalfa field before and after cutting

There is interest in and significant uncertainty about the emissions of oxygenated volatile organic compounds (ox VOCs) from vegetation to the atmosphere. Here, we measured the fluxes of selected oxVOCs from an alfalfa field, before, during, and after cutting, using a combination of disjunct eddy covariance and proton-transfer-reaction mass spectrometry. Over the course of 1 day a significant methanol flux of 4 mg m -2 h -1 was observed from undisturbed alfalfa with a maximum at 0800 LT, possibly caused by the evaporation of dew. A smaller release of hexenals during this day (0.04 mg m -2h -1) demonstrated the sensitivity of the method. Other results suggested that acetaldehyde and acetone were released in the afternoon but were lost by dry deposition in the evening and morning; deposition velocities were estimated to be 0.2 cm s -1 (acetaldehyde) and 0.09 cm s -1 (acetone). After the alfalfa was cut the emissions of methanol, acetaldehyde, acetone, and hexenals were significantly enhanced and remained high for three days during which the alfalfa was drying. After a rainstorm the oxVOC emissions from the cut, wet alfalfa increased even more. Nighttime measurements yielded low oxVOC fluxes in general, but the high variability of the concentrations during the night and the high degree of correlation between different oxVOCs suggest that the nighttime releases of oxVOCs from alfalfa were nonzero. This work suggests that the global source of oxVOCs due to the production of hay is of minor importance. The emission flux of methanol from vegetation during the growing season may be very large on a global basis.
Experimental study on the performance of light and dense backfills

Numerical modeling is a cost-effective and important approach to examine the long-term performance of engineered materials. However, to identify the appropriate constitutive model for a particular material it is necessary to measure physical properties in a laboratory. Laboratory experiments provide the data from which the input parameters for the selected model can be interpreted. This paper studies the mechanical behaviour of two clay-based sealing materials — light backfill and dense backfill — recommended for use in disposal of nuclear waste in a proposed Canadian repository. Test specimens of light and dense backfills were saturated in a triaxial cell and then subjected to specified isotropic and shearing stress paths to measure consolidation and shear characteristics. The triaxial results are interpreted in a critical state context. The light backfill results suggest that it has similar stress–strain behaviour to a bentonite–sand buffer, which has a similar composition, but different preparation pro.
Mapping City Lights With Nighttime Data from the DMSP Operational Linescan System

The Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has a unique capability to detect low levels of visible and near-infrared (VNIR) radiance at night. With the OLS "VIS" band data, it is possible to detect clouds illuminated by moonlight, plus lights from cities, towns, industrial sites, gas pares, and ephemeral events such as fires and lightning illuminated clouds. This paper presents methods which have been developed for detecting and geolocating VNIR emission sources with nighttime DMSP-OLS data and the analysis of image time series to identify spatially stable emissions from cities, towns, and industrial sites. Results are presented for the United States.
An ICA-based approach for image quality assessment

In this paper, we propose an ICA-based approach for assessing image quality. Independent component analysis (ICA), which is a kind of fundamental statistical model for natural images, could model images as linear superpositions of basis images. The features given by ICA are suitable for image quality assessment because they resemble the representation given by simple-cells in the mammalian primary visual cortex. The steps of the proposed approach are listed concisely as follows: estimation of basis images in the ICA model; image features extraction from reference images and their corresponding distorted images; calculation of image quality scores or scales. Our experimental results show that the proposed method could achieve competitive performance with other two typical models, Structure SIMilarity (SSIM) and Visual Information Fidelity (VIF) by being tested on LIVE Subjective database. Some factors that may influence the performance results, such as the size of sliding window, the total number of image patches, are also discussed.
Interannual changes of temperature and ozone: Relationship between the lower and upper stratosphere

Changes of stratospheric dynamical structure and ozone are investigated in observations of the lower stratosphere, from meteorological analyses and Total Ozone Mapping Spectrometer (TOMS) ozone, and in contemporaneous observations of the upper stratosphere and mesosphere, from the French lidar at Observatoire de Haute-Provence (OHP). Interannual changes in the lower stratosphere are shown to be accompanied by coherent changes in the upper stratosphere and mesosphere. Over the 1980s and 1990s, both operate coherently with anomalous forcing of the residual mean circulation. Changes of temperature and ozone at OHP have sign and structure consistent with interannual changes of meridional transport. They reflect a poleward expansion and contraction of warm ozone-rich air, compensated by opposite changes of the polar-night vortex.