648 research outputs found
Use of near infrared reflectance spectroscopy to predict nitrogen uptake by winter wheat within fields with high variability in organic matter
In this study, the ability to predict N-uptake in winter wheat crops using NIR-spectroscopy on soil samples was evaluated. Soil samples were taken in unfertilized plots in one winter wheat field during three years (1997-1999) and in another winter wheat field nearby in one year (2000). Soil samples were analyzed for organic C content and their NIR-spectra. N-uptake was measured as total N-content in aboveground plant materials at harvest. Models calibrated to predict N-uptake were internally cross validated and validated across years and across fields. Cross-validated calibrations predicted N-uptake with an average error of 12.1 to 15.4 kg N ha-1. The standard deviation divided by this error (RPD) ranged between 1.9 and 2.5. In comparison, the corresponding calibrations based on organic C alone had an error from 11.7 to 28.2 kg N ha-1 and RPDs from 1.3 to 2.5. In three of four annual calibrations within a field, the NIR-based calibrations worked better than the organic C based calibrations. The prediction of N-uptake across years, but within a field, worked slightly better with an organic C based calibration than with a NIR based one, RPD = 1.9 and 1.7 respectively. Across fields, the corresponding difference was large in favour of the NIR-calibration, RPD = 2.5 for the NIR-calibration and 1.5 for the organic C calibration. It was concluded that NIR-spectroscopy integrates information about organic C with other relevant soil components and therefore has a good potential to predict complex functions of soils such as N-mineralization. A relatively good agreement of spectral relationships to parameters related to the N-mineralization of datasets across the world suggests that more general models can be calibrated
Influence of the Interplanetary Convective Electric Field on the Distribution of Heavy Pickup Ions Around Mars
This study obtains a statistical representation of 2â15Â keV heavy ions outside of the Martianâinduced magnetosphere and depicts their organization by the solar wind convective electric field (ESW). The overlap in the lifetime of Mars Global Surveyor (MGS) and Mars Express (MEX) provides a period of nearly three years during which magnetometer data from MGS can be used to estimate the direction of ESW in order to better interpret MEX ion data. In this paper we use MGS estimates of ESW to express MEX ion measurements in MarsâSunâElectric field (MSE) coordinates. A new methodological technique used in this study is the limitation of the analysis to a particular instrument mode for which the overlap between proton contamination and plume observations is rare. This allows for confident energetic heavy ion identification outside the induced magnetosphere boundary. On the dayside, we observe high count rates of 2â15Â keV heavy ions more frequently in the +ESW hemisphere (+ZMSE) than in the âESW hemisphere, but on the nightside the reverse asymmetry was found. The results are consistent with planetary origin ions being picked up by the solar wind convective electric field. Though a field of view hole hinders quantification of plume fluxes and velocity space, this new energetic heavy ion identification technique means that Mars Express should prove useful in expanding the time period available to assess general plume loss variation with drivers.Plain Language SummaryThe location and flow direction of oxygen escaping Marsâ atmosphere is organized by a globalâscale electric field associated with the Sunâs flowing magnetic field. While the Mars Express (MEX) satellite is less well equipped than Mars Atmosphere and Volatile Evolution (MAVEN) to estimate exact flux values of ions accelerated by this electric field, our demonstration that MEX can see this population statistically opens a new window of time (preâMAVEN) to studies of the variability of this atmospheric escape channel.Key PointsMars Express heavy ion data outside the magnetic boundary show a statistical asymmetry consistent with other energetic plume studiesThe energetic plume is more prevalent on the dayside (i.e., XÂ >Â 0), while for XÂ <Â 0 higher count rates in the +ESW direction were not seenFor a specific instrument setting, overlap between proton contamination and the plume is rare, allowing for confident plume identificationPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142551/1/jgra53999.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142551/2/jgra53999_am.pd
Nonreciprocal Directional Dichroism and Toroidalmagnons in Helical Magnets
We investigate a dynamical magnetoelectric effect due to a magnetic resonance
in helical spin structures through the coupling between magnetization and
electric polarization via a spin current mechanism. We show that the magnon has
both the dynamical magnetic moment and the electric moment
(), i.e., a dynamical toroidal moment,
under external magnetic fields, and thus it is named the {\em toroidalmagnon}.
The toroidalmagnon exists in most conical spin structures owing to the
generality of the spin current mechanism. In the absorption of electromagnetic
waves, the toroidalmagnon excitation process generally induces a nonreciprocal
directional dichroism as a consequence of an interference of the magnetic and
electric responses.Comment: 5 pages, 2 figure
Circadian rhythm of hepatic cytosolic and nuclear estrogen receptors
The distribution of estrogen receptor between the cytosolic and nuclear compartments were evaluated in liver of male rats to determine whether a circadian rhythm exists. Cytosolic receptor reached a maximum level at 400 hours and a minimum at 2000 and 2400 hr. Nuclear receptor reached a maximum level at 800 hr and was lowest at 1600 and 2000 hr. Serum estradiol levels were also highest at 800 hr and lowest at 1600 hr. The variations in cytosolic and nuclear receptors are not reciprocal; in fact, the overall content of receptor in the liver is not constant and also displays a circadian rhythm. © 1986 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
Shot Noise in Mesoscopic Diffusive Andreev Wires
We study shot noise in mesoscopic diffusive wires between a normal and a
superconducting terminal. We particularly focus on the regime, in which the
proximity-induced reentrance effect is important. We will examine the
difference between a simple Boltzmann-Langevin description, which neglects
induced correlations beyond the simple conductivity correction, and a full
quantum calculation. In the latter approach, it turns out that two Andreev
pairs propagating coherently into the normal metal are anti-correlated for
E<E_c, where E_c=D/L^2 is the Thouless energy. In a fork geometry the
flux-sensitive suppression of the effective charge was confirmed
experimentally.Comment: 12 pages, proceedings of the NATO ARW MQO, Bled, Sloveni
Equivalence of three-dimensional spacetimes
A solution to the equivalence problem in three-dimensional gravity is given
and a practically useful method to obtain a coordinate invariant description of
local geometry is presented. The method is a nontrivial adaptation of Karlhede
invariant classification of spacetimes of general relativity. The local
geometry is completely determined by the curvature tensor and a finite number
of its covariant derivatives in a frame where the components of the metric are
constants. The results are presented in the framework of real two-component
spinors in three-dimensional spacetimes, where the algebraic classifications of
the Ricci and Cotton-York spinors are given and their isotropy groups and
canonical forms are determined. As an application we discuss Goedel-type
spacetimes in three-dimensional General Relativity. The conditions for local
space and time homogeneity are derived and the equivalence of three-dimensional
Goedel-type spacetimes is studied and the results are compared with previous
works on four-dimensional Goedel-type spacetimes.Comment: 13 pages - content changes and corrected typo
Gold/Silica biochips: applications to Surface Plasmon Resonance and fluorescence quenching
We report Gold/Silica biochips for low cost biosensor devices. Firstly, the
study of biochemical interactions on silica by means of Surface Plasmon
Resonance (SPR) is presented. Secondly, Gold/Silica biochips are employed to
reduce the strong quenching that occurs when a fluorophore is close to the gold
surface. Furthermore, the control of the Silica-like thickness allows
optimizing the distance between the metallic surface and the fluorophore in
order to enhance the fluorescent signal. These results represent the first
steps towards highly sensitive, specific and low cost biosensors based, for
example, on Surface Plasmon Coupled Emission (SPCE) techniques
The host ubiquitin-dependent segregase VCP/p97 is required for the onset of human cytomegalovirus replication
The human cytomegalovirus major immediate early proteins IE1 and IE2 are critical drivers of virus replication and are considered pivotal in determining the balance between productive and latent infection. IE1 and IE2 are derived from the same primary transcript by alternative splicing and regulation of their expression likely involves a complex interplay between cellular and viral factors. Here we show that knockdown of the host ubiquitin-dependent segregase VCP/p97, results in loss of IE2 expression, subsequent suppression of early and late gene expression and, ultimately, failure in virus replication. RNAseq analysis showed increased levels of IE1 splicing, with a corresponding decrease in IE2 splicing following VCP knockdown. Global analysis of viral transcription showed the expression of a subset of viral genes is not reduced despite the loss of IE2 expression, including UL112/113. Furthermore, Immunofluorescence studies demonstrated that VCP strongly colocalised with the viral replication compartments in the nucleus. Finally, we show that NMS-873, a small molecule inhibitor of VCP, is a potent HCMV antiviral with potential as a novel host targeting therapeutic for HCMV infection
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