Multiphase smoothed-particle hydrodynamics

We adapt the smoothed-particle hydrodynamics (SPH) technique to allow a multiphase fluid in which SPH particles of widely differing density may be freely intermixed. Applications include modelling of galaxy formation and cooling flows

Deregulation of the Australian Wheat Export Market: What Happened to Wheat Prices?

This paper investigates whether deregulation of the Australian wheat export market induced a structural change in the price data generation process. We examine the unit root properties of Western Australian wheat prices by testing for the possibility of single and double structural breaks in the price series. Daily prices for the period 20th of May 2003 to 14th of September 2010 are used. We find that the wheat price series has a unit root with two structural breaks but neither break coincided with the time when the Wheat Export Marketing Act 2008 came into effect on 1 July 2008. We conclude that change in local market behaviour would have started prior to actual deregulation with subsequent effect on local price.deregulation, unit root, structural breaks, wheat price, Agribusiness, Demand and Price Analysis, Marketing, Q13, Q18,

The Effects of Time and Topography on Deep Carbon Storage in the Clarks River Valley of Western Kentucky

Soil organic carbon (SOC) dynamics at depths greater than one meter in valley bottoms are not well understood. This study examines the stock of SOC with depth across alluvial landforms in the Clarks River National Wildlife Refuge. Nine cores along three transects from terraces to floodplains and adjacent channel bars were collected to depths of 4 meters or refusal. Bulk density, clay content, and loss-on-ignition were used to estimate stocks. Age estimates based on radiocarbon suggest the landforms range in age from 7975 to 52 yr BP. Average SOC and carbon (C) flux varied with values of 1.76 kg/m2 ± 0.54, 2.21x10-4 kg/m2/yr in the terraces, 1.05 kg/m2 ± 0.36, 200x10-4 kg/m2/yr in the floodplains and 1.47 kg/m2 ± 0.53, 300x10-4 kg/m2/yr in the bars. The percentage of total SOC by landform observed in buried soils (not modern surface soil) is 50% in bars, 71% in floodplains, and 77% in terraces. Analysis of Variance and post-hoc tests showed that the mean stock of buried soils in the floodplain are significantly lower than terrace (p= 0.0009), and bar sites (p= 0.01). These lower values may be due to labile C oxidizing in soils that have not developed enough for soil processes to stabilize SOC. The higher SOC in bars is most likely related to new C being submerged and protected from oxidation. Infrequent flooding and greater soil development in terraces allows for the accumulation of clay as well as the protection and stabilization of microaggregates containing SOC at depth

VALLEY BOTTOM POSITION AND THE OCCURRENCE OF PALEOSOLS AFFECT SOC DYNAMICS

Soil organic carbon (SOC) storage in depositional zones has been a growing topic of interest in recent years as these areas may be sinks of SOC. However, SOC dynamics greater than 1 m in depth in river valley bottom soils are not well understood. This study examines the soil organic carbon along three alluvial landscape positions in the forested, humid-subtropical setting of the Clarks River in the western Kentucky portion of the Mississippi River basin. These soil and depositional profiles range in age from ~8,000 years ago to modern, 21 cal yr. BP, (BP = AD 2010). The mean surface soil SOC stocks (kg/m2) decrease from Floodplains (2.62 ± 0.3), Terraces (2.31 ± 0.21) to Bars (1.32 ± 0.24); whereas, the mean stocks of buried layers (buried soils and lithologic discontinuities) decrease from Terraces (4.13 ± 0.24), Bars (3.07 ± 0.54) to Floodplains (2.68 ± 0.24). Total SOC estimates in the buried layers make up over half of the SOC inventory for all landforms. The isotopic composition of SOC (δ13C) at all sites is consistent with C3 vegetation. The depth profiles show that δ13C becomes less negative with depth, likely due to a combination of the Suess effect and microbial decomposition. A classification and regression tree analysis shows that soil horizon, pH, landscape position, and magnetic susceptibility are significant predictors of mean SOC content. Notably, the tree shows that alkaline pH (\u3e7.9) is an important predictor in higher mean SOC. These alkaline soil pH values are found in buried calcareous soils with pedogenic carbonate in the Clarks River Terraces, where acidified samples were found to have higher mean SOC. A 14C age from SIC shows that this carbonate may have formed under drier conditions of the mid-Holocene hypsithermal. This age association suggests that the legacy of buried soils in valley bottoms plays a role in deep SOC storage today. This study showed that buried soils and sediments contain the majority of the SOC in the Clarks River, while landform position and a calcareous paleosol played an important role in the storage of that SOC

Landform Mapping of The Clarks River Alluvial System Using LiDAR DEMs

The Clarks River is located in western Kentucky near the city of Benton. It travels through and weathers lacustrine or lake deposits as well as fluvial or river deposits. These deposits are also overlain by loess deposited from the last glacial maximum. Historically, people have taken advantage of these rich deposits for agriculture which has led to increased settlement. With increased settlement, the river has experienced alteration. The west fork of the Clarks River has been channelized while the east fork of the Clarks River has managed to remain un-channelized and has since been allowed to run relatively freely. Detailed landform and geomorphic maps for Western Kentucky are scares or lack the level of detailed needed for this study. This project attempted to develop a landform map for a 5 km by 5 km section of the east fork of the Clarks River, focusing on an area being monitored by Murray State University. Elevation data were obtained from five foot LiDAR digital elevation models (DEMs), and analyzed using 3D Analyst and Spatial Analyst tools in ArcMap. Transect lines were used in ArcMap to determine the location of different landforms in relation to the main channel of the Clarks River. Soils data were also added to determine how different soil types relate to differences in elevation

Detection of a Third Planet in the HD 74156 System Using the Hobby-Eberly Telescope

We report the discovery of a third planetary mass companion to the G0 star HD 74156. High precision radial velocity measurements made with the Hobby-Eberly Telescope aided the detection of this object. The best fit triple Keplerian model to all the available velocity data yields an orbital period of 347 days and minimum mass of 0.4 M_Jup for the new planet. We determine revised orbital periods of 51.7 and 2477 days, and minimum masses of 1.9 and 8.0 M_Jup respectively for the previously known planets. Preliminary calculations indicate that the derived orbits are stable, although all three planets have significant orbital eccentricities (e = 0.64, 0.43, and 0.25). With our detection, HD 74156 becomes the eighth normal star known to host three or more planets. Further study of this system's dynamical characteristics will likely give important insight to planet formation and evolutionary processes.Comment: 24 pages, 4 tables, 6 figures. Accepted for publication in ApJ. V2 fixed table 4 page overrun. V3 added reference

The Cepheid distance to the Local Group Galaxy NGC 6822

Recent estimates of the Cepheid distance modulus of NGC 6822 differ by 0.18 mag. To investigate this we present new multi-epoch JHKs photometry of classical Cepheids in the central region of NGC 6822 and show that there is a zero-point difference from earlier work. These data together with optical and mid-infrared observations from the literature are used to derive estimates of the distance modulus of NGC 6822. A best value of 23.40 mag is adopted, based on an LMC distance modulus of 18.50 mag. The standard error of this quantity is ~0.05 mag. We show that to derive consistent moduli from Cepheid observations at different wavelengths, it is necessary that the fiducial LMC period-luminosity relations at these wavelengths should refer to the same subsample of stars. Such a set is provided. A distance modulus based on RR Lyrae variables agrees with the Cepheid result.Comment: accepted for publication in MNRA

PERCIEVED IMPACT OF NEWSPAPER USAGE ON ACADEMIC PERFORMANCE OF STUDENTS OF FEDERAL UNIVERSITY OF AGRICULTURE, MAKURDI

This paper examines the perceived impact of newspaper usage among University of Agriculture, Makurdi students and its impact on their academic performance. The overall objective is to assess the level of newspaper usage and students’ perception on the availability and accessibility of newspaper in the library. This study also highlights some of the challenges students face in using newspapers and proffer workable solutions. The population was made up of 150 students of University of Agriculture, Makurdi, comprising of undergraduates and postgraduates. The survey research method was adopted. The respondents were selected through random sampling of registered users the library at that particular time. As shown in the findings, the students use newspaper mostly for academic purpose followed by other purposes. The study revealed adequate but untimely provision of newspaper

Grip and muscle strength dynamometry in acute burn injury: Evaluation of an updated assessment protocol

External stabilization is reported to improve reliability of hand held dynamometry, yet this has not been tested in burns. We aimed to assess the reliability of dynamometry using an external system of stabilization in people with moderate burn injury and explore construct validity of strength assessment using dynamometry. Participants were assessed on muscle and grip strength three times on each side. Assessment occurred three times per week for up to four weeks. Within session reliability was assessed using intraclass correlations calculated for within session data grouped prior to surgery, immediately after surgery and in the sub-acute phase of injury. Minimum detectable differences were also calculated. In the same timeframe categories, construct validity was explored using regression analysis incorporating burn severity and demographic characteristics. Thirty-eight participants with total burn surface area 5 – 40% were recruited. Reliability was determined to be clinically applicable for the assessment method (intraclass correlation coefficient \u3e0.75) at all phases after injury. Muscle strength was associated with sex and burn location during injury and wound healing. Burn size in the immediate period after surgery and age in the sub-acute phase of injury were also associated with muscle strength assessment results. Hand held dynamometry is a reliable assessment tool for evaluating within session muscle strength in the acute and sub-acute phase of injury in burns up to 40% total burn surface area. External stabilization may assist to eliminate reliability issues related to patient and assessor strength