4,774 research outputs found
Synthesis optimization and charge carrier transfer mechanism in LiLuSiO<sub>4</sub>:Ce, Tm storage phosphor
No full textLiLuSiO4:Ce and LiLuSiO4:Ce, Tm show very efficient charge carrier storage properties upon beta irradiation after samples have received treatment in vacuum. They outperform the commercial storage phosphor BaFBr(I):Eu2+ in many aspects. The influence of the synthesis conditions, Ce and Tm concentration, nonstoichiometry and codoping with Ca, Hf, Al and Ge are reported. Based on the results of the synthesis optimization, thermoluminescence (TL) emission and TL excitation spectra a mechanism of charge carrier transfer, storage, and recombination during irradiation and thermal or optical readout is proposed.Accepted Author ManuscriptRST/Fundamental Aspects of Materials and EnergyRST/Luminescence Material
Quasi-cyclic Generalized LDPC codes with low error floors
No full textIn this paper, a novel methodology for designing structured generalized LDPC (G-LDPC) codes is presented. The proposed design results in quasi-cyclic G-LDPC codes for which efficient encoding is feasible through shift-register-based circuits. The structure imposed on the bipartite graphs, together with the choice of simple component codes, leads to a class of codes suitable for fast iterative decoding. A pragmatic approach to the construction of G-LDPC codes is proposed. The approach is based on the substitution of check nodes in the protograph of a low-density parity-check code with stronger nodes based, for instance, on Hamming codes. Such a design approach, which we call LDPC code doping, leads to low-rate quasi-cyclic G-LDPC codes with excellent performance in both the error floor and waterfall regions on the additive white Gaussian noise channel
Examination of Abiotic Drivers and Their Influence on Spartina alterniflora Biomass over a Twenty-eight Year Period Using Landsat 5 TM Satellite Imagery of the Central Georgia Coast
No full textWe examined the influence of abiotic drivers on inter-annual and phenological patterns of aboveground biomass for Marsh Cordgrass, Spartina alterniflora, on the Central Georgia Coast. The linkages between drivers and plant response via soil edaphic factors are captured in our graphical conceptual model. We used geospatial techniques to scale up in situ measurements of aboveground S. alterniflora biomass to landscape level estimates using 294 Landsat 5 TM scenes acquired between 1984 and 2011. For each scene we extracted data from the same 63 sampling polygons, containing 1222 pixels covering about 1.1 million m2. Using univariate and multiple regression tests, we compared Landsat derived biomass estimates for three S. alterniflora size classes against a suite of abiotic drivers. River discharge, total precipitation, minimum temperature, and mean sea level had positive relationships with and best explained biomass for all dates. Additional results, using seasonally binned data, indicated biomass was responsive to changing combinations of variables across the seasons. Our 28-year analysis revealed aboveground biomass declines of 33%, 35%, and 39% for S. alterniflora tall, medium, and short size classes, respectively. This decline correlated with drought frequency and severity trends and coincided with marsh die-backs events and increased snail herbivory in the second half of the study period.ProQuest Traditional Publishing Optio
Inhibition of gene expression in human cells through small molecule-RNA interactions
No full textSmall molecules that bind their biological receptors with high affinity and selectivity can be isolated from randomized pools of combinatorial libraries. RNA-protein interactions are important in many cellular functions, including transcription, RNA splicing, and translation. One example of such interactions is the mechanism of trans-activation of HIV-1 gene expression that requires the interaction of Tat protein with the trans-activation responsive region (TAR) RNA, a 59-base stem-loop structure located at the 5' end of all nascent HIV-1 transcripts. Here we demonstrate the isolation of small TAR RNA-binding molecules from an encoded combinatorial library. We have made an encoded combinatorial tripeptide library of 24,389 possible members from D-and L-alpha amino acids on TentaGel resin. Using on-bead screening we have identified a small family of mostly heterochiral tripeptides capable of structure-specific binding to the bulge loop of TAR RNA. In vitro binding studies reveal stereospecific discrimination when the best tripeptide ligand is compared with diastereomeric peptide sequences. In addition, the most strongly binding tripeptide was shown to suppress transcriptional activation by Tat protein in human cells with an IC(50) of approximately 50 nM. Our results indicate that tripeptide RNA ligands are cell permeable, nontoxic to cells, and capable of inhibiting expression of specific genes by interfering with RNA-protein interactions
Targeting vascular endothelial growth factor receptor-1 and -3 with cediranib (AZD2171): effects on migration and invasion of gastrointestinal cancer cell lines
No full textUnravelling morphological changes of the human talus during growth
No full textThe human talus, being located between the lower limb and foot, plays an essential role in distributing the weight of the body during locomotion. One of its most important functions during this process is in allowing for foot movements while efficiently dividing weight between its anterior and posterior portions, where it articulates with the navicular and calcaneus, respectively [1]. As such, the talus plays a pivotal role in the different stages of human locomotion, from crawling, to initial bipedal acquisition, to full striding bipedalism at age 8 [1]. Unfortunately, little is known about the morphological changes of the talus during the first years of life, when infants acquire upright posture and gait maturation.
Using a (semi)landmark based approach we analyse an ontogenetic sample of modern human tali with the aim of exploring the morphological variation of the talus during growth. From this we assess if the variation may then be related to the acquisition and transition to full bipedal locomotion, which might ultimately provide insight into the evolution of hominin bipedalism.
The sample consists of 21 juvenile tali aged between 1.5 years and 11 years: 12 individuals from the Collection of Bologna, Italy (sex and age at death known) [2]; five from the archaeological sample of Roccapelago (Italy) [3]; four from the archaeological sample of Norris Farms #36 (Illinois, USA). All specimens were microCT scanned with a resolution of 20-40 μm. Avizo 9.3® (Visualization Sciences Group, SAS) was used to evaluate the quality of and pre-process the reconstructed scan data (e.g. crop or resample). Segmentation of the image data was performed using the MIA-clustering method [4] and then processed in Medtool 4.2 (Dr. Pahr Ingenieurs.e.U) to obtain 3D meshes of each talus. A template of 11 landmarks, 61 curve semilandmarks and 144 surface semilandmarks was created in Viewbox (dHAL Software) and applied to the 21 tali. The (semi)landmark configuration was superimposed by Generalized Procrustes Analysis, and semilandmarks were allowed to slide against recursive updates of the Procrustes consensus [5]. Finally, a form space Principal Component Analysis was carried out to explore talar shape variation during growth. Data were processed in R 3.4.3 (The R Foundation for Statistical Computing, 2017).
The first three PCs explain 92.9% of the total variation. Most of the morphometric variation is explained by PC1 (89.8%), i.e. ontogenetic allometry, where negative scores account for small, sub-parallelepiped talar morphology (the youngest individuals), while positive scores account for an elongation of the entire body of the talus, due to the development of the neck, and a clear growth of the lateral malleolar facet, while the posterior side of the trochlear facet is not well defined yet. The anterior calcaneal facet is well developed since the youngest phases (negative scores), while the posterior calcaneal facet becomes larger, less triangular, and more concave towards PC1 positive. PC2 (1.7%) and PC3 (1.4%) describe only subtle morphological differences. Negative values of PC2 account for a longer lateral ridge, that shortens along positive values, due to the growth of the talar head, development of the neck, trochlea, and lateral malleolar facet, with a more concave aspect of the lateral side. It is also possible to discern a narrowing of the sulcus tali and a clear medial rotation of the talar head. PC3 negative scores show a more compact shape, that becomes higher along positive values with the development of the posterior calcaneal facet and head.
This study is part of an ongoing project focusing on ontogenetic changes. Here we present preliminary results showing how external talar morphology varies during the early stages of human bipedalism. Future analyses will combine external morphological analyses with an assessment of trabecular bone architecture, thus providing a more holistic vision of these changes during development.
Acknowledgements
This project is funded by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 724046 - SUCCESS); website: http://www.erc-success.eu/. We are grateful to Dr Mirko Traversari for his willingness on the use of the Roccapelago sample.
References:
[1] Hellier, C.A., & Jeffery, N. 2006. Morphological plasticity in the juvenile talus. Foot and Ankle surgery, 12(3), 139-147.
[2] Belcastro, M.G., Bonfiglioli, B., Pedrosi, M.E., Zuppello, M., Tanganelli, V., & Mariotti, V. 2017. The history and composition of the identified human skeletal collection of the Certosa Cemetery (Bologna, Italy, 19th‐20th century). International Journal of Osteoarchaeology. DOI: 10.1002/oa.2605
[3] Figus, C., Traversari M., Scalise L. M., Oxilia G., Vazzana A., Buti L., Sorrentino R., Gruppioni G., Benazzi, S. 2017. The study of commingled non-adult human remains: Insights from the 16th-18th centuries community of Roccapelago (Italy). Journal of Archaeological Science: Reports, 14:382-391
[4] Dunmore C.J., Wollny G., Skinner M.M. (2018) MIA-Clustering: a novel method for segmentation of paleontological material. PeerJ 6:e4374
[5] Rohlf, F.J., Slice, D. 1990. Extensions of the Procrustes method for the optimal superimposition of landmarks. Syst. Biol. 39, 40-59
JOB Queries Executed by PostgreSQL 10.5
No full textThis dataset contains executions of each query from the Join Order Benchmark on PostgreSQL 10.5. The data is loaded, appropriate indexes are created, and each query is ran once with a cold cache.
The format of each file is the output of pre-pending EXPLAIN (FORMAT JSON, ANALYZE) to each SQL query. Queries are executed in a VirtualBox VM created by Vagrant. The VM has two cores and 8GB of memory. The PostgreSQL buffer size is set to 4GB. The VM is ran on a machine with 16GB of RAM and a Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
JOB Queries Executed by PostgreSQL 10.5
No full textThis dataset contains executions of each query from the Join Order Benchmark on PostgreSQL 10.5. The data is loaded, appropriate indexes are created, and each query is ran once with a cold cache.
The format of each file is the output of pre-pending EXPLAIN (FORMAT JSON, ANALYZE) to each SQL query. Queries are executed in a VirtualBox VM created by Vagrant. The VM has two cores and 8GB of memory. The PostgreSQL buffer size is set to 4GB. The VM is ran on a machine with 16GB of RAM and a Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
Estimating tropical forest biomass with a combination of SAR image texture and Landsat TM data:an assessment of predictions between regions
No full textQuantifying the above ground biomass of tropical forests is critical for understanding the dynamics of carbon fluxes between terrestrial ecosystems and the atmosphere, as well as monitoring ecosystem responses to environmental change. Remote sensing remains an attractive tool for estimating tropical forest biomass but relationships and methods used at one site have not always proved applicable to other locations. This lack of a widely applicable general relationship limits the operational use of remote sensing as a method for biomass estimation, particularly in high biomass ecosystems. Here, multispectral Landsat TM and JERS-1 SAR data were used together to estimate tropical forest biomass at three separate geographical locations: Brazil, Malaysia and Thailand. Texture measures were derived from the JERS-1 SAR data using both wavelet analysis and Grey Level Co-occurrence Matrix methods, and coupled with multispectral data to provide inputs to artificial neural networks that were trained under four different training scenarios and validated using biomass measured from 144 field plots. When trained and tested with data collected from the same location, the addition of SAR texture to multispectral data showed strong correlations with above ground biomass (r = 0.79, 0.79 and 0.84 for Thailand, Malaysia and Brazil respectively). Also, when networks were trained and tested with data from all three sites, the strength of correlation (r = 0.55) was stronger than previously reported results from the same sites that used multispectral data only. Uncertainty in estimating AGB from different allometric equations was also tested but found to have little effect on the strength of the relationships observed. The results suggest that the inclusion of SAR texture with multispectral data can go someway towards providing relationships that are transferable across time and space, but that further work is required if satellite remote sensing is to provide robust and reliable methodologies for initiatives such as Reducing Emissions from Deforestation and Degradation (REDD+). (C) 2012 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved
GA Landsat 5 TM Analysis Ready Data Collection 3
No full textMaintenance and Update Frequency: asNeededStatement: This product is derived from the USGS Landsat Collection 1 archive.
The Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43A1 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters dataset was provided by the National Aeronautics and Space Administration (NASA). It was produced daily using 16 days of Terra and Aqua MODIS data at 500 m resolution.
The ozone data was provided by Environment Canada.
The Aerosol Optical Thickness data was provided by the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
The Precipitable Water for Entire Atmosphere data was provided by the National Oceanic and Atmospheric Administration (NOAA) / Earth System Research Laboratory (ESRL) / Physical Sciences Division (PSD).
The baseline Digital Surface Model (DSM) data produced from the Shuttle Radar Topography Mission (SRTM) was provided by the National Geospatial-Intelligence Agency (NGA).
Level 1 Collection 1 data was provided by the United States Geological Survey (USGS)'s Earth Resources Observation and Science (EROS) Center.<b>BACKGROUND</b><br/><p><br/><p>The United States Geological Survey's (USGS) Landsat satellite program has been capturing images of the Australian continent for more than 30 years. This data is highly useful for land and coastal mapping studies. <br/><p>In particular, the light reflected from the Earth’s surface (surface reflectance) is important for monitoring environmental resources – such as agricultural production and mining activities – over time. <br/><p>We need to make accurate comparisons of imagery acquired at different times, seasons and geographic locations. However, inconsistencies can arise due to variations in atmospheric conditions, sun position, sensor view angle, surface slope and surface aspect. These need to be reduced or removed to ensure the data is consistent and can be compared over time. <br/><p> </p><br/><b>WHAT THIS PRODUCT OFFERS</b><br/><p><br/><p>GA Landsat 5 TM Analysis Ready Data Collection 3 takes Landsat 5 Thematic Mapper (TM) imagery captured over the Australian continent and corrects for inconsistencies across land and coastal fringes. The result is accurate and standardised surface reflectance data, which is instrumental in identifying and quantifying environmental change. <br/><p><br/><p>The TM instrument is an advanced, multispectral scanning, Earth resources sensor which is designed to categorise the Earth's surface. It is particularly useful for agricultural applications and identification of land use. <br/><p><br/><p>This product is a single, cohesive Analysis Ready Data (ARD) package, which allows you to analyse surface reflectance data as is, without the need to apply additional corrections. <br/><p><br/><p>It contains three sub-products that provide corrections or attribution information:<br/><p><br/><p> 1) GA Landsat 5 TM NBAR Collection 3 <br/><p> 2) GA Landsat 5 TM NBART Collection 3<br/><p> 3) GA Landsat 5 TM OA Collection 3<br/><p><br/><p>The resolution is a 30 m grid based on the USGS Landsat Collection 1 archive
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