Effect of soil properties on pyroxasulfone bioactivity and field application rates

Non-Peer ReviewedThe relationship between pyroxasulfone bioactivity and soil properties has not been investigated in a wide range of soils typical of western Canada. In this study, 47 soils from Saskatchewan, Manitoba and Alberta, with varying organic matter content (1.5 to 22.1%), pH (5.0 to 7.9), and clay content (6.8 to 59.4%) were used to evaluate the effect of soil properties on pyroxasulfone bioactivity and its relevance to field application rates. Bioactivity was assessed by measuring the reduction of sugar beet shoot length after 7 days in response to 0, 92, 184, and 368 μg ai kg-1 pyroxasulfone concentration in soil. Multiple regression analysis showed that pyroxasulfone bioactivity was related to soil organic matter content, pH and clay content. Grouping the soils according to these properties allowed for a summarization of pyroxasulfone field application rates required to achieve bioactivity based on the magnitude of sugar beet shoot length inhibition (%). The estimated field application rates ranged from less than 120 to 480 g ai ha-1

Finite-element modelling of mechanical behaviour of rapid manufactured textiles

Novel textile-like linked structures, realised using a rapid manufacturing (RM) process, have been proposed and developed recently. Various potential applications exist, and in most cases the mechanical performance must be evaluated. The present paper outlines a method to solve this problem by employing finite-element (FE) techniques at two scales, using the results of analysis at the meso-scale (the scale of the repeating unit) to provide equivalent non-linear spring behaviour for each textile link at the macro-scale. Validation with experimental test data from each scale was performed and these results are presented. Initial results overestimated mechanical performance. Microscopy suggested that this may be due to edge porosity in the specimens, and the dimensions of the FE models were adjusted accordingly as an initial approach to account for this. Predictions incorporating this modification exhibited excellent agreement with experimental measurements. The current work demonstrates both a technique, which could be automated for use in the design environment, and the potential value of developing an integrated process simulation to provide local material property data for the FE model

A comparison of terrestrial laser scanning and structure-from-motion photogrammetry as methods for digital outcrop acquisition

Terrestrial laser scanning (TLS) has been used extensively in Earth Science for acquisition of digital outcrop data over the past decade. Structure-from-­motion (SfM) photogrammetry has recently emerged as an alternative and competing technology. The real-world performance of these technologies for ground-based digital outcrop acquisition is assessed using outcrops from North East England and the United Arab Emirates. Both TLS and SfM are via­ble methods, although no single technology is universally best suited to all situations. There are a range of practical considerations and operating conditions where each method has clear advantages. In comparison to TLS, SfM benefits from being lighter, more compact, cheaper, more easily replaced and repaired, with lower power requirements. TLS in comparison to SfM provides intrinsically validated data and more robust data acquisition in a wide range of operating conditions. Data post-processing is also swifter. The SfM data sets were found to contain systematic inaccuracies when compared to their TLS counterparts. These inaccuracies are related to the triangulation approach of the SfM, which is distinct from the time-of-flight principle employed by TLS. An elaborate approach is required for SfM to produce comparable results to TLS under most circumstances

Distinct Magnetic Phase Transition at the Surface of an Antiferromagnet

In the majority of magnetic systems the surface is required to order at the same temperature as the bulk. In the present Letter, we report a distinct and unexpected surface magnetic phase transition at a lower temperature than the Néel temperature. Employing grazing incidence x-ray resonant magnetic scattering, we have observed the near-surface behavior of uranium dioxide. UO2 is a noncollinear, triple-q, antiferromagnet with the U ions on a face-centered cubic lattice. Theoretical investigations establish that at the surface the energy increase—due to the lost bonds—is reduced when the spins near the surface rotate, gradually losing their component normal to the surface. At the surface the lowest-energy spin configuration has a double-q (planar) structure. With increasing temperature, thermal fluctuations saturate the in-plane crystal field anisotropy at the surface, leading to soft excitations that have ferromagnetic XY character and are decoupled from the bulk. The structure factor of a finite two-dimensional XY model fits the experimental data well for several orders of magnitude of the scattered intensity. Our results support a distinct magnetic transition at the surface in the Kosterlitz-Thouless universality class

Campylobacter infection and household factors are associated with childhood growth in urban Bangladesh : an analysis of the MAL-ED study

The dual burden of enteric infection and childhood malnutrition continues to be a global health concern and a leading cause of morbidity and death among children. Campylobacter infection, in particular, is highly prevalent in low- and middle-income countries, including Bangladesh. We examined longitudinal data to evaluate the trajectories of change in child growth, and to identify associations with Campylobacter infection and household factors. The study analyzed data from 265 children participating in the MAL-ED Study in Mirpur, Bangladesh. We applied latent growth curve modelling to evaluate the trajectories of change in children’s height, as measured by length-for-age z-score (LAZ), from age 0–24 months. Asymptomatic and symptomatic Campylobacter infections were included as 3- and 6-month lagged time-varying covariates, while household risk factors were included as time-invariant covariates. Maternal height and birth order were positively associated with LAZ at birth. An inverse association was found between increasing age and LAZ. Campylobacter infection prevalence increased with age, with over 70% of children 18–24 months of age testing positive for infection. In the final model, Campylobacter infection in the preceding 3-month interval was negatively associated with LAZ at 12, 15, and 18 months of age; similarly, infection in the preceding 6-month interval was negatively associated with LAZ at 15, 18, and 21 months of age. Duration of antibiotic use and access to treated drinking water were negatively associated with Campylobacter infection, with the strength of the latter effect increasing with children’s age. Campylobacter infection had a significant negative effect on child’s growth and this effect was most powerful between 12 and 21 months. The treatment of drinking water and increased antibiotic use have a positive indirect effect on linear child growth trajectory, acting via their association with Campylobacter infection

On the magnetism of Ln{2/3}Cu{3}Ti{4}O{12} (Ln = lanthanide)

The magnetic and thermodynamic properties of the complete Ln$_{2/3}$Cu$_3$Ti$_4$O$_{12}$ series were investigated. Here $Ln$ stands for the lanthanides La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. %Most of the compounds were prepared as single phase polycrystalline powder %without any traces of impurities. Marginal amounts of %impurities $(< 2$ were detected $Ln=$ Gd, Er, and Tm. %Significant amounts of impurity phases were found for $Ln=$ Ce and Yb. All the samples investigated crystallize in the space group $Im\bar{3}$ with lattice constants that follow the lanthanide contraction. The lattice constant of the Ce compound reveals the presence of Ce$^{4+}$ leading to the composition Ce$_{1/2}$Cu$_3$Ti$_4$O$_{12}$. From magnetic susceptibility and electron-spin resonance experiments it can be concluded that the copper ions always carry a spin $S=1/2$ and order antiferromagnetically close to 25\,K. The Curie-Weiss temperatures can approximately be calculated assuming a two-sublattice model corresponding to the copper and lanthanide ions, respectively. It seems that the magnetic moments of the heavy rare earths are weakly coupled to the copper spins, while for the light lanthanides no such coupling was found. The $4f$ moments remain paramagnetic down to the lowest temperatures, with the exception of the Tm compound, which indicates enhanced Van-Vleck magnetism due to a non-magnetic singlet ground state of the crystal-field split $4f$ manifold. From specific-heat measurements we accurately determined the antiferromagnetic ordering temperature and obtained information on the crystal-field states of the rare-earth ions. The heat-capacity results also revealed the presence of a small fraction of Ce$^{3+}$ in a magnetic $4f^1$ state.Comment: 10 pages, 10 figure

General Spectral Flow Formula for Fixed Maximal Domain

We consider a continuous curve of linear elliptic formally self-adjoint differential operators of first order with smooth coefficients over a compact Riemannian manifold with boundary together with a continuous curve of global elliptic boundary value problems. We express the spectral flow of the resulting continuous family of (unbounded) self-adjoint Fredholm operators in terms of the Maslov index of two related curves of Lagrangian spaces. One curve is given by the varying domains, the other by the Cauchy data spaces. We provide rigorous definitions of the underlying concepts of spectral theory and symplectic analysis and give a full (and surprisingly short) proof of our General Spectral Flow Formula for the case of fixed maximal domain. As a side result, we establish local stability of weak inner unique continuation property (UCP) and explain its role for parameter dependent spectral theory.Comment: 22 page

Cosmological Effects of Radion Oscillations

We show that the redshift of pressureless matter density due to the expansion of the universe generically induces small oscillations in the stabilized radius of extra dimensions (the radion field). The frequency of these oscillations is proportional to the mass of the radion and can have interesting cosmological consequences. For very low radion masses $m_b$ ($m_b\sim10-100 H_0\simeq10^{-32} eV$) these low frequency oscillations lead to oscillations in the expansion rate of the universe. The occurrence of acceleration periods could naturally lead to a resolution of the coincidence problem, without need of dark energy. Even though this scenario for low radion mass is consistent with several observational tests it has difficulty to meet fifth force constraints. If viewed as an effective Brans-Dicke theory it predicts $\omega=-1+\frac{1}{D}$ ($D$ is the number of extra dimensions), while experiments on scales larger than $1mm$ imply $\omega>2500$. By deriving the generalized Newtonian potential corresponding to a massive toroidally compact radion we demonstrate that Newtonian gravity is modified only on scales smaller than $m_b^{-1}$. Thus, these constraints do not apply for $m_b>10^{-3} eV$ (high frequency oscillations) corresponding to scales less than the current experiments ($0.3mm$). Even though these high frequency oscillations can not resolve the coincidence problem they provide a natural mechanism for dark matter generation. This type of dark matter has many similarities with the axion.Comment: Accepted in Phys. Rev. D. Clarifying comments added in the text and some additional references include

The design, construction and performance of the MICE scintillating fibre trackers

This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2011 ElsevierCharged-particle tracking in the international Muon Ionisation Cooling Experiment (MICE) will be performed using two solenoidal spectrometers, each instrumented with a tracking detector based on diameter scintillating fibres. The design and construction of the trackers is described along with the quality-assurance procedures, photon-detection system, readout electronics, reconstruction and simulation software and the data-acquisition system. Finally, the performance of the MICE tracker, determined using cosmic rays, is presented.This work was supported by the Science and Technology Facilities Council under grant numbers PP/E003214/1, PP/E000479/1, PP/E000509/1, PP/E000444/1, and through SLAs with STFC-supported laboratories. This work was also supportedby the Fermi National Accelerator Laboratory, which is operated by the Fermi Research Alliance, under contract No. DE-AC02-76CH03000 with the U.S. Department of Energy, and by the U.S. National Science Foundation under grants PHY-0301737,PHY-0521313, PHY-0758173 and PHY-0630052. The authors also acknowledge the support of the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan

Magnetic fields in supernova remnants and pulsar-wind nebulae

We review the observations of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe) that give information on the strength and orientation of magnetic fields. Radio polarimetry gives the degree of order of magnetic fields, and the orientation of the ordered component. Many young shell supernova remnants show evidence for synchrotron X-ray emission. The spatial analysis of this emission suggests that magnetic fields are amplified by one to two orders of magnitude in strong shocks. Detection of several remnants in TeV gamma rays implies a lower limit on the magnetic-field strength (or a measurement, if the emission process is inverse-Compton upscattering of cosmic microwave background photons). Upper limits to GeV emission similarly provide lower limits on magnetic-field strengths. In the historical shell remnants, lower limits on B range from 25 to 1000 microGauss. Two remnants show variability of synchrotron X-ray emission with a timescale of years. If this timescale is the electron-acceleration or radiative loss timescale, magnetic fields of order 1 mG are also implied. In pulsar-wind nebulae, equipartition arguments and dynamical modeling can be used to infer magnetic-field strengths anywhere from about 5 microGauss to 1 mG. Polarized fractions are considerably higher than in SNRs, ranging to 50 or 60% in some cases; magnetic-field geometries often suggest a toroidal structure around the pulsar, but this is not universal. Viewing-angle effects undoubtedly play a role. MHD models of radio emission in shell SNRs show that different orientations of upstream magnetic field, and different assumptions about electron acceleration, predict different radio morphology. In the remnant of SN 1006, such comparisons imply a magnetic-field orientation connecting the bright limbs, with a non-negligible gradient of its strength across the remnant.Comment: 20 pages, 24 figures; to be published in SpSciRev. Minor wording change in Abstrac