Podzolization as a deferralitization process: a study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin

Morphological, geochemical and mineralogical studies were carried out in a representative soil catena of the low-elevation plateaux of the upper Amazon Basin to interpret the steps and mechanisms involved in the podzolization of low-activity clay soils. The soils are derived from Palaeozoic sandstones. They consist of Hydromorphic Podzols under tree savannah in the depressions of the plateaux and predominantly of Acrisols covered by evergreen forest elsewhere.Incipient podzolization in the uppermost Acrisols is related to the formation of organic-rich A and Bhs horizons slightly depleted in fine-size particles by both mechanical particle transfer and weathering. Weathering of secondary minerals by organic acids and formation of organo-metallic complexes act simultaneously over short distances. Their vertical transfer is limited. Selective dissolution of aluminous goethite, then gibbsite and finally kaolinite favour the preferential cheluviation of first Fe and secondly Al. The relatively small amount of organo-metallic complexes produced is related to the quartzitic parent materials, and the predominance of Al over Fe in the spodic horizons is due to the importance of gibbsite in these low-activity clay soils.Morphologically well-expressed podzols occur in strongly iron-depleted topsoils of the depression. Mechanical transfer and weathering of gibbsite and kaolinite by organic acids is enhanced and leads to residual accumulation of sands. Organo-metallic complexes are translocated in strongly permeable sandy horizons and impregnate at depth the macro-voids of embedded soil and saprolite materials to form the spodic Bs and 2BCs horizons. Mechanical transfer of black particulate organic compounds devoid of metals has occurred later within the sandy horizons of the podzols. Their vertical transfer has formed well-differentiated A and Bh horizons. Their lateral removal by groundwater favours the development of an albic E horizon. In an open and waterlogged environment, the general trend is therefore towards the removal of all the metals that have initially accumulated as a response to the ferralitization process and have temporarily been sequestrated in organic complexes in previous stages of soil podzolization.

Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Postural control under visual and proprioceptive perturbations during double and single limb stances: Insights for balance training

Single Limb Stance under visual and proprioceptive disturbances is largely used in clinical settings in order to improve balance in a wide range of functional disabilities. However, the proper role of vision and proprioception in SLS is not completely understood. The objectives of this study were to test the hypotheses that when ankle proprioception is perturbed, the role of vision in postural control increases according to the difficulty of the standing task. And to test the effect of vision during postural adaptation after withdrawal of the somesthetic perturbation during double and single limb stance. Eleven males were submitted to double (DLS) and single limb (SLS) stances under conditions of normal or reduced vision, both with normal and perturbed proprioception. Center of pressure parameters were analyzed across conditions. Vision had a main effect in SLS, whereas proprioception perturbation showed effects only during DLS. Baseline stability was promptly achieved independently of visual input after proprioception reintegration. In conclusion, the role of vision increases in SLS. After proprioception reintegration, vision does not affect postural recovery. Balance training programs must take that into account. © 2011 Elsevier Ltd.

Hutchison Family Papers - Accession 19

The Hutchison Family Papers consist of diaries, journals, speeches, correspondence, genealogical material and financial papers, concerning the personal and business affairs of a Rock Hill family. Subjects include post-colonial life in the Carolinas, the antebellum plantation system in South Carolina, post-Civil War cotton farming, especially the Rock Hill Cotton Mill, and Rock Hill during World War I. There is also material concerning relations and negotiations with the Catawba Indians by David Hutchison who was one of several commissioners designated by the South Carolina legislature to investigate Catawba land claims and leasing practices; and historical sketches of Glencairn Garden, the White House and the Oakland Avenue Presbyterian Church, all located in Rock Hill, South Carolina. There are also included in the “General Correspondence and Related Papers” series such records as: last will and testament, inventory lists, certificates of indentured servants, legislative acts, (eg. 1840 Treaty with the Catawba Indians) and other similar documents. Correspondents include Jude Grimke, A.E. Hutchison, David Hutchison, Hiram Hutchison, James Moore, John N. Morehead and Thomas Spratt.

Chemical contaminants in juvenile gray whales (Eschrichtius robustus) from a subsistence harvest in Arctic feeding grounds

Gray whales are coastal migratory baleen whales that are benthic feeders. Most of their feeding takes place in the northern Pacific Ocean with opportunistic feeding taking place during their migrations and residence on the breeding grounds. The concentrations of organochlorines and trace elements were determined in tissues and stomach contents of juvenile gray whales that were taken on their Arctic feeding grounds in the western Bering Sea during a Russian subsistence harvest. These concentrations were compared to previously published data for contaminants in gray whales that stranded along the west coast of the US during their northbound migration. Feeding in coastal waters during their migrations may present a risk of exposure to toxic chemicals in some regions. The mean concentration (standard error of the mean, SEM) of Σ PCBs [1400 (130) ng/g, lipid weight] in the blubber of juvenile subsistence whales was significantly lower than the mean level [27 000 (11 000) ng/g, lipid weight] reported previously in juvenile gray whales that stranded in waters off the west coast of the US. Aluminum in stomach contents of the subsistence whales was high compared to other marine mammal species, which is consistent with the ingestion of sediment during feeding. Furthermore, the concentrations of potentially toxic chemicals in tissues were relatively low when compared to the concentrations in tissues of other marine mammals feeding at higher trophic levels. These chemical contaminant data for the subsistence gray whales substantially increase the information available for presumably healthy animals.

Yellowstone Super-Volcano: Evalutaion, Potential Threats, and Possible effects on Nebraska Citizens Health and Prosperity

Abstract Yellowstone National Park is located over a hot spot under the North American tectonic plate and holds a potentially explosive super-volcano that has the ability to cause deadly consequences on the North American continent. After an eruption the surrounding region would see the greatest devastation, covered by pyroclastic deposits and thick ash fall exterminating most all life and destroying all structures in its path. In landscapes of greater distance from the event the consequences will be less dramatic yet still substantial. Records of previous eruption data from the Yellowstone super-volcano show that the ash fall out from the eruption can cover areas as large as one million square kilometers and could leave Nebraska covered in ash up to 10 centimeters thick. This would cause destruction of agriculture, extensive damage to structures, decreased temperatures, and potential respiratory hazards. The effects of volcanic ash on the human respiratory system have been shown to cause acute symptoms from heavy exposure. Symptoms include nasal irritation, throat irritation, coughing, and if preexisting conditions are present some can develop bronchial symptoms, which can last for a few days. People with bronchitis and asthma are shown to experience airway irritation and uncomfortable breathing. In most occurrences, exposure of volcanic ash is too short to cause long-term health hazards. Wearing facial protection can alleviate much of the symptoms. Most of the long-term ramifications of the eruption will be from the atmospheric changes caused from disruption of solar radiation, which will affect much of the global population. The most pertinent concerns for Nebraska citizens are from the accumulation of ash deposits over the landscape and the climatic perturbations. Potential mitigation procedures are essential to prepare our essentially unaware population of the threat that they may soon face if the volcano continues on its eruption cycle.

A search for anisotropy in the arrival directions of ultra high energy cosmic rays recorded at the Pierre Auger Observatory

Observations of cosmic rays arrival directions made with the Pierre Auger Observatory have previously provided evidence of anisotropy at the 99% CL using the correlation of ultra high energy cosmic rays (UHECRs) with objects drawn from the Veron-Cetty Veron catalog. In this paper we report on the use of three catalog independent methods to search for anisotropy. The 2pt-L, 2pt+ and 3pt methods, each giving a different measure of self-clustering in arrival directions, were tested on mock cosmic ray data sets to study the impacts of sample size and magnetic smearing on their results, accounting for both angular and energy resolutions. If the sources of UHECRs follow the same large scale structure as ordinary galaxies in the local Universe and if UHECRs are deflected no more than a few degrees, a study of mock maps suggests that these three method can efficiently respond to the resulting anisotropy with a P-value = 1.0% or smaller with data sets as few as 100 events. using data taken from January 1, 2004 to July 31, 2010 we examined the 20, 30, ... , 110 highest energy events with a corresponding minimum energy threshold of about 49.3 EeV. The minimum P-values found were 13.5% using the 2pt-L method, 1.0% using the 2pt+ method and 1.1% using the 3pt method for the highest 100 energy events. In view of the multiple (correlated) scans performed on the data set, these catalog-independent methods do not yield strong evidence of anisotropy in the highest energy cosmic rays.

Description of atmospheric conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)

Atmospheric conditions at the site of a cosmic ray observatory must be known for reconstructing observed extensive air showers. The Global Data Assimilation System (GDAS) is a global atmospheric model predicated on meteorological measurements and numerical weather predictions. GDAS provides altitude-dependent profiles of the main state variables of the atmosphere like temperature, pressure, and humidity. The original data and their application to the air shower reconstruction of the Pierre Auger Observatory are described. By comparisons with radiosonde and weather station measurements obtained on-site in Malargue and averaged monthly models, the utility of the GDAS data is shown. (C) 2012 Elsevier B.V. All rights reserved.

Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory

The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna sensor. As the ultra-wideband reception of pulses is not widely discussed in antenna literature, we review the relevant antenna characteristics and enhance theoretical considerations towards the impulse response of antennas including polarization effects and multiple signal reflections. On the basis of the vector effective length we study the transient response characteristics of three candidate antennas in the time domain. Observing the variation of the continuous galactic background intensity we rank the antennas with respect to the noise level added to the galactic signal.

The rapid atmospheric monitoring system of the Pierre Auger Observatory

The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 10(17) eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the observations for variations in atmospheric conditions, atmospheric monitoring is performed at regular intervals ranging from several minutes (for cloud identification) to several hours (for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity). In 2009, the monitoring program was upgraded to allow for additional targeted measurements of atmospheric conditions shortly after the detection of air showers of special interest, e. g., showers produced by very high-energy cosmic rays or showers with atypical longitudinal profiles. The former events are of particular importance for the determination of the energy scale of the Observatory, and the latter are characteristic of unusual air shower physics or exotic primary particle types. The purpose of targeted (or "rapid") monitoring is to improve the resolution of the atmospheric measurements for such events. In this paper, we report on the implementation of the rapid monitoring program and its current status. The rapid monitoring data have been analyzed and applied to the reconstruction of air showers of high interest, and indicate that the air fluorescence measurements affected by clouds and aerosols are effectively corrected using measurements from the regular atmospheric monitoring program. We find that the rapid monitoring program has potential for supporting dedicated physics analyses beyond the standard event reconstruction.

SEARCH FOR POINT-LIKE SOURCES OF ULTRA-HIGH ENERGY NEUTRINOS AT THE PIERRE AUGER OBSERVATORY AND IMPROVED LIMIT ON THE DIFFUSE FLUX OF TAU NEUTRINOS

The surface detector array of the Pierre Auger Observatory can detect neutrinos with energy E-nu between 10(17) eV and 10(20) eV from point-like sources across the sky south of +55 degrees and north of -65 degrees declinations. A search has been performed for highly inclined extensive air showers produced by the interaction of neutrinos of all flavors in the atmosphere (downward-going neutrinos), and by the decay of tau leptons originating from tau neutrino interactions in Earth's crust (Earth-skimming neutrinos). No candidate neutrinos have been found in data up to 2010 May 31. This corresponds to an equivalent exposure of similar to 3.5 years of a full surface detector array for the Earth-skimming channel and similar to 2 years for the downward-going channel. An improved upper limit on the diffuse flux of tau neutrinos has been derived. Upper limits on the neutrino flux from point-like sources have been derived as a function of the source declination. Assuming a differential neutrino flux k(PS) . E-nu(-2). from a point-like source, 90% confidence level upper limits for k(PS) at the level of approximate to 5x10(-7) and 2.5x10(-6) GeV cm(-2) s(-1) have been obtained over a broad range of declinations from the searches for Earth-skimming and downward-going neutrinos, respectively.

A search for point sources of EeV neutrons

A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from -90 degrees to +15 degrees in declination using four different energy ranges above 1 EeV (10(18) eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.

LARGE-SCALE DISTRIBUTION OF ARRIVAL DIRECTIONS OF COSMIC RAYS DETECTED ABOVE 10(18) eV AT THE PIERRE AUGER OBSERVATORY

A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10(18) eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 10(18) eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 10(18) eV from stationary Galactic sources densely distributed in the Galactic disk and predominantly emitting light particles in all directions.

Measurement of the proton-air cross section at root s=57 TeV with the Pierre Auger Observatory

We report a measurement of the proton-air cross section for particle production at the center-of-mass energy per nucleon of 57 TeV. This is derived from the distribution of the depths of shower maxima observed with the Pierre Auger Observatory: systematic uncertainties are studied in detail. Analyzing the tail of the distribution of the shower maxima, a proton-air cross section of [505 +/- 22(stat)(-36)(+28)(syst)] mb is found.

Dry spell mitigation to upgrade semi-arid rainfed agriculture : Water harvesting and soil nutrient management for smallholder maize cultivation in Machakos, Kenya

Improvements in on-farm water and soil fertility management through water harvesting may prove key to up-grade smallholder farming systems in dry sub-humid and semi-arid sub-Sahara Africa (SSA). The currently experienced yield levels are usually less than 1 t ha-1, i.e., 3-5 times lower than potential levels obtained by commercial farmers and researchers for similar agro-hydrological conditions. The low yield levels are ascribed to the poor crop water availability due to variable rainfall, losses in on-farm water balance and inherently low soil nutrient levels. To meet an increased food demand with less use of water and land in the region, requires farming systems that provide more yields per water unit and/or land area in the future. This thesis presents the results of a project on water harvesting system aiming to upgrade currently practised water management for maize (Zea mays, L.) in semi-arid SSA. The objectives were to a) quantify dry spell occurrence and potential impact in currently practised small-holder grain production systems, b) test agro-hydrological viability and compare maize yields in an on-farm experiment using combinations supplemental irrigation (SI) and fertilizers for maize, and c) estimate long-term changes in water balance and grain yields of a system with SI compared to farmers currently practised in-situ water harvesting. Water balance changes and crop growth were simulated in a 20-year perspective with models MAIZE1&2. Dry spell analyses showed that potentially yield-limiting dry spells occur at least 75% of seasons for 2 locations in semi-arid East Africa during a 20-year period. Dry spell occurrence was more frequent for crop cultivated on soil with low water-holding capacity than on high water-holding capacity. The analysis indicated large on-farm water losses as deep percolation and run-off during seasons despite seasonal crop water deficits. An on-farm experiment was set up during 1998-2001 in Machakos district, semi-arid Kenya. Surface run-off was collected and stored in a 300m3 earth dam. Gravity-fed supplemental irrigation was carried out to a maize field downstream of the dam. Combinations of no irrigation (NI), SI and 3 levels of N fertilizers (0, 30, 80 kg N ha-1) were applied. Over 5 seasons with rainfall ranging from 200 to 550 mm, the crop with SI and low nitrogen fertilizer gave 40% higher yields (**) than the farmers’ conventional in-situ water harvesting system. Adding only SI or only low nitrogen did not result in significantly different yields. Accounting for actual ability of a storage system and SI to mitigate dry spells, it was estimated that a farmer would make economic returns (after deduction of household consumption) between year 2-7 after investment in dam construction depending on dam sealant and labour cost used. Simulating maize growth and site water balance in a system of maize with SI increased annual grain yield with 35 % as a result of timely applications of SI. Field water balance changes in actual evapotranspiration (ETa) and deep percolation were insignificant with SI, although the absolute amount of ETa increased with 30 mm y-1 for crop with SI compared to NI. The dam water balance showed 30% productive outtake as SI of harvested water. Large losses due to seepage and spill-flow occurred from the dam. Water productivity (WP, of ETa) for maize with SI was on average 1 796 m3 per ton grain, and for maize without SI 2 254 m3 per ton grain, i.e, a decerase of WP with 25%. The water harvesting system for supplemental irrigation of maize was shown to be both biophysically and economically viable. However, adoption by farmers will depend on other factors, including investment capacity, know-how and legislative possibilities. Viability of increased water harvesting implementation in a catchment scale needs to be assessed so that other down-stream uses of water remains uncompromised.