Noise and dynamical pattern selection

In pattern forming systems such as Rayleigh-Benard convection or directional solidification, a large number of linearly stable, patterned steady states exist when the basic, simple steady state is unstable. Which of these steady states will be realized in a given experiment appears to depend on unobservable details of the system's initial conditions. We show, however, that weak, Gaussian white noise drives such a system toward a preferred wave number which depends only on the system parameters and is independent of initial conditions. We give a prescription for calculating this wave number, analytically near the onset of instability and numerically otherwise.Comment: 12 pages, REVTEX, no figures. Submitted to Phys. Rev. Let

Crustal heterogeneity of the moon viewed from the Galileo SSI camera: Lunar sample calibrations and compositional implications

Summaries are given of the spectral calibration, compositional parameters, nearside color, and limb and farside color of the Moon. The farside of the Moon, a large area of lunar crust, is dominated by heavily cratered terrain and basin deposits that represent the products of the first half billion years of crustal evolution. Continuing analysis of the returned lunar samples suggest a magma ocean and/or serial magmatism model for evolution of the primordial lunar crust. However, testing either hypothesis requires compositional information about the crustal stratigraphy and lateral heterogeneity. Resolution of this important planetary science issue is dependent on additional data. New Galileo multispectral images indicate previously unknown local and regional compositional diversity of the farside crust. Future analysis will focus on individual features and a more detailed assessment of crustal stratigraphy and heterogeneity

Vlakdekkend archeologisch onderzoek op de Arsenaalsite te Mechelen

Dit rapport werd ingediend bij het agentschap samen met een aantal afzonderlijke digitale bijlagen. Een aantal van deze bijlagen zijn niet inbegrepen in dit pdf document en zijn niet online beschikbaar. Sommige bijlagen (grondplannen, fotos, spoorbeschrijvingen, enz.) kunnen van belang zijn voor een betere lezing en interpretatie van dit rapport. Indien u deze bijlagen wenst te raadplegen kan u daarvoor contact opnemen met: [email protected]

Near-Earth asteroid sample return missions

The rate of discovery of new NEAs and the success of D-S 1 and NEAR-Shoemaker, suggest that sample return from NEAs is now technically feasible. Here we present a summary of a recent workshop on the topic

Visible Color and Photometry of Bright Materials on Vesta

The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of ~70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5]

Contrast-enhanced ultrasound as support for prostate brachytherapy treatment planning

Purpose: To investigate the possibility of localization of intraprostatic lesions (IL) with contrast-enhanced ultrasound (CEUS) to support the brachytherapy treatment planning of temporary implants. Material and methods: Two brachytherapy treatment plans were generated for 8 patients treated with external beam radiotherapy and pulsed-dose rate brachytherapy boost for prostate cancer. The first and second brachytherapy treatment plan was without and with knowledge of the localization of the ILs, respectively. Pairwise comparison was performed on prostate, rectum, and urethra dose-volume parameters and total reference air kerma (TRAK)-values. Results: Coverage of the ILs by the 140% isodose was increased from mean 66.0-67.7% for the standard plan to mean 92.5-95.7% for the adapted plan. The mean D90 of the ILs increased from 1.49-1.57 Gy/pulse to 1.76-1.81 Gy/pulse. Dose-volume parameters for the prostate, rectum, and urethra and the TRAK did not change. Conclusions: CEUS technique is a promising method for IL localization to aid in brachytherapy treatment planning. Dose coverage on the IL could be improved without any increase of dose in organs at ris

Pesticide Use in South Africa: One of the Largest Importers of Pesticides in Africa

South Africa is a diverse country, with a diverse environment that is home to more than 49 000 000 people. Pesticide usage is very often necessary to maintain both agricultural productivity as well as human health. The climatic conditions range from semi-tropic to semi-arid regions. Although the majority of the country has summer rainfall, the south western coastal region is predominantly a winter rainfall area. These variations in climate allows for a wide variety of crops, from tropical fruit to maize and tree plantations. Each individual crop is susceptible to a unique host of pests that in-turn require a unique mixture of pesticides to ensure the best resulting turnover. Currently, South Africa has more than 500 registered pesticides (Pesticide Action Network (PAN), 2010) and is one of the four largest importers of pesticides in sub-Saharan Africa (Osbanjo et al., 2002). In 2006 the import of insecticides, fungicides and herbicides that were packaged for retail totalled $ 170 056 000 the main import partners being Australia, China, Germany and the United States of America (USA) (International Trade Centre, 2011). These pesticides are used in almost every facet of our everyday lives; ensuring the quantity and quality of food we eat to managing the number of rodents and insects in our homes. Although it is evident that there is a vast amount of pesticides present in the South African environment, there is very limited data on the production of pesticides. The last published data indicates that in 2002 around 10 000 kℓ of liquid insecticides was produced exclusively for crop protection of which 43% consisted of organophosphates. During the same year 2 800-tonnes of solid insecticides were produced (Statistics South Africa, 2003). Although the usefulness of pesticides cannot be denied, the negative environmental and human health effects cannot be ignored. In South Africa, a number of environmental and anthropogenic factors have to be considered before the impact of large-scale pesticide use can be assessed. South Africa is a water poor country, with water resources being utilised to their maximum capacity. As discussed by Dabrowski et al. (2009), the trade-off between the economic benefits of exporting agricultural products has to be measured against the loss of water, not only through crop irrigation but also through water quality degradation. The article highlighted this aspect through the calculation of virtual water volumes. These calculated volumes indicated that to ensure sufficient dilution of all agrochemicals, to an acceptable water quality level (used in a typical farming situation applying current-use pesticides), was greater than the amount of water needed for irrigation. The seriousness of these scenarios is highlighted in literature where a diverse array of agricultural chemicals has been measured during run-off events, by once-off sampling and by water monitoring during the growing seasons. Detectable levels of atrazine, terbuthylazine, simazine, acetochlor (Du Preez et al., 2005), DDT and its metabolites, endosulfan, hexachlorocyclohexane (HCH), heptachlor, aldrin, dieldrin, endrin, chlordane (Fatoki et al., 2003), azinophos-methyl, chloropyriphos (Schultz et al., 2001; Dabrowski et al., 2002) prothiofos (Schultz, 2001), malathion, zendoxsulfan (Thiere &  Schultz, 2004), cypermethrin and fenvalerate (Bollmohr et al., 2007), to name a few, have all been measured in South African waters. Pesticides in the aquatic environment have the potential to affect all end-users, including both humans and wildlife. South Africa has the distinction of being one of the countries with the most species richness in the world. To date more than 900 bird species as well as over 200 mammals, call South Africa home. Of these mammals, seven species are endangered and 30 are vulnerable according to the 2004 IUCN red data list (IUCN, 2010). These endangered species include bats, moles, shrews and mice that are often insectivorous, thus increasing their risk of unintentional exposure to pesticides. Within avian populations, 11 species are listed as critically endangered and 43 species as vulnerable. The sensitivity of avian species to pollutants has been widely reported. With this unique diversity of species, South Africans have a responsibility towards maintaining the viability of ecosystems and natural habitats to ensure the continued existence of these creatures. This objective is not only morally relevant but also economically relevant especially in a country where tourism creates over 400 000 jobs and contributes approximately 8% to the GDP. Few studies have reported the levels of insecticides in wildlife species. However, pesticides have been detected in wild bird species (Van Wyk et al., 2001; Bouwman et al., 2008), as well as in indigenous fish species (Barnhoorn et al., 2009), indicating pesticide contamination within various habitats. This is of particular concern due to the health risks associated with many pesticides

Use of tetravalent galabiose for inhibition of Streptococcus suis serotype 2 infection in a mouse model

Peer reviewe

Impact heat driven volatile redistribution at Occator crater on Ceres as a comparative planetary process

Hydrothermal processes in impact environments on water-rich bodies such as Mars and Earth are relevant to the origins of life. Dawn mapping of dwarf planet (1) Ceres has identified similar deposits within Occator crater. Here we show using Dawn high-resolution stereo imaging and topography that Ceres' unique composition has resulted in widespread mantling by solidified water- and salt-rich mud-like impact melts with scattered endogenic pits, troughs, and bright mounds indicative of outgassing of volatiles and periglacial-style activity during solidification. These features are distinct from and less extensive than on Mars, indicating that Occator melts may be less gas-rich or volatiles partially inhibited from reaching the surface. Bright salts at Vinalia Faculae form thin surficial precipitates sourced from hydrothermal brine effusion at many individual sites, coalescing in several larger centers, but their ages are statistically indistinguishable from floor materials, allowing for but not requiring migration of brines from deep crustal source(s). Dawn mission's second extended phase provided high resolution observations of Occator crater of the dwarf planet Ceres. Here, the authors show stereo imaging and topographic maps of this crater revealing the influence of crustal composition on impact related melt and hydrothermal processes, and compare features to those on Mars, Earth and the Moon

Investigating the Origin of Bright Materials on Vesta: Synthesis, Conclusions, and Implications

The Dawn spacecraft started orbiting the second largest asteroid (4) Vesta in August 2011, revealing the details of its surface at an unprecedented pixel scale as small as approx.70 m in Framing Camera (FC) clear and color filter images and approx.180 m in the Visible and Infrared Spectrometer (VIR) data in its first two science orbits, the Survey Orbit and the High Altitude Mapping Orbit (HAMO) [1]. The surface of Vesta displays the greatest diversity in terms of geology and mineralogy of all asteroids studied in detail [2, 3]. While the albedo of Vesta of approx.0.38 in the visible wavelengths [4, 5] is one of the highest among all asteroids, the surface of Vesta shows the largest variation of albedos found on a single asteroid, with geometric albedos ranging at least from approx.0.10 to approx.0.67 in HAMO images [5]. There are many distinctively bright and dark areas observed on Vesta, associated with various geological features and showing remarkably different forms. Here we report our initial attempt to understand the origin of the areas that are distinctively brighter than their surroundings. The dark materials on Vesta clearly are different in origin from bright materials and are reported in a companion paper [6]