Digging up an Archaeologist

No abstract is available at this time

Phase behavior of repulsive polymer-tethered colloids

We report molecular dynamics simulations of a system of repulsive, polymer-tethered colloidal particles. We use an explicit polymer model to explore how the length and the behavior of the polymer (ideal or self-avoiding) affect the ability of the particles to organize into ordered structures when the system is compressed to moderate volume fractions. We find a variety of different phases whose origin can be explained in terms of the configurational entropy of polymers and colloids. Finally, we discuss and compare our results to those obtained for similar systems using simplified coarse-grained polymer models, and set the limits of their applicability.Comment: 7 pages, 5 figures. Published in the Journal of Chemical Physic

Post Wildfire Vegetation Response to the Wildland-Urban Interface: A Case Study of the Station Fire

In the past, wildfires served as a method for mother nature to promote biodiversity and to help maintain a functioning ecosystem. However, climate change alters the fire regime, significantly impacting vegetation recovery. Human disturbances and increased land use and land cover heighten vegetation disruption and abundance after a fire. Wildland-urban interface (WUI) – the region where the vegetation intermingles with the roads, houses, and human-made structures – threatens vegetation and the human population. Overall vegetation recovery after the Station Fire of 2009 spread through the San Gabriel Mountains, Los Angeles County was observed using Digital Elevation Model (DEM), Normalized Difference Vegetation Index (NDVI), and Normalized Difference Burn Ratio (nDBR) spectral indices. In addition, Light Detection and Ranging (LiDAR) images were used to measure aboveground biomass (AGB). The study analyzed vegetation biomass recovery by comparing human disturbances and the level of fire severity within the Station Fire perimeter. Low and moderate fire severity were compared in detail against WUI and non-WUI regions by quantifying the amount of biomass in the specified regions. Linear regression model results showed vegetation recovery rates were slower in WUI regions than in non-WUI regions despite having similar regeneration patterns while AGB rebound was similar across both region categories

Control of a charging station for electric vehicles

A weighted average current control applied to a three-phase inductor-capacitor-inductor grid-connected battery charger for electric vehicles is presented in this paper. The proposed controller is based on a combination of the partial currents of the system (inverter and grid currents), which are feedback into the control loop. Therefore, by using this approach a reduction of the system order is achieved. The proposed controller allows a bidirectional control of the converter currents, thus allowing both, a controlled charge of the battery and the injection of the current with low distortion in the grid. Further, the implemented controller does not needs to measure the inverter currents. The control strategy is validated with simulation results. © Published under licence by IOP Publishing Ltd

Produção de mudas de Schinus terebinthifolius Raddi (aroeira-vermelha) em diferentes substratos.

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Variáveis morfológicas na produção de mudas de Allophylus edulis (St Hil.) Radl. (vacum) em diferentes substratos.

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Características físicas de substratos para produção de mudas de Allophylus edulis (ST Hil.) Radl. e Schinus terebinthifolius.

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A simple prescription for simulating and characterizing gravitational arcs

Simple models of gravitational arcs are crucial to simulate large samples of these objects with full control of the input parameters. These models also provide crude and automated estimates of the shape and structure of the arcs, which are necessary when trying to detect and characterize these objects on massive wide area imaging surveys. We here present and explore the ArcEllipse, a simple prescription to create objects with shape similar to gravitational arcs. We also present PaintArcs, which is a code that couples this geometrical form with a brightness distribution and adds the resulting object to images. Finally, we introduce ArcFitting, which is a tool that fits ArcEllipses to images of real gravitational arcs. We validate this fitting technique using simulated arcs and apply it to CFHTLS and HST images of tangential arcs around clusters of galaxies. Our simple ArcEllipse model for the arc, associated to a S\'ersic profile for the source, recovers the total signal in real images typically within 10%-30%. The ArcEllipse+S\'ersic models also automatically recover visual estimates of length-to-width ratios of real arcs. Residual maps between data and model images reveal the incidence of arc substructure. They may thus be used as a diagnostic for arcs formed by the merging of multiple images. The incidence of these substructures is the main factor preventing ArcEllipse models from accurately describing real lensed systems.Comment: 12 pages, 11 figures, accepted for publication in A&

Whetstones from Bronze Age hill forts of North Eastern Italy

A group of Bronze Age whetstones from Protohistoric hill forts, locally called Castellieri, of eastern Friuli Venezia Giulia (north eastern Italy) has been studied using different techniques, including non destructive methods such as X-ray computed micro-tomography and portable X-ray fluorescence, in order to characterize the raw material and define its origin. The obtained results suggest that small pebbles of reddish subarkose and quartz arenites collected from the gravel deposits of river Isonzo, perhaps deriving from Val Gardena Formation outcrops, were exploited for the production of the studied artefacts during the Bronze Age. These data complement our knowledge about the lithic raw materials exploitation strategies during the ancient phase of Castellieri culture, almost exclusively based on local rock type