54 research outputs found
Contrasting soil organic matter properties of a Hawaiian Andosol revealed by fractionations procedures
Volcanic Andosols are recognized by their strong capacity to accumulate soil organic carbon (SOC), and for presenting a singular aggregation pattern. However, the factors that govern their SOC storage and aggregation hierarchy are still poorly understood. In this way, the objective of this study was to evaluate the soil organic matter (SOM) properties of an Andosol through CN analysis, NMR spectroscopy, and scanning electron microscopy (SEM) with subsequent nano scale secondary ion mass spectrometry (NanoSIMS) analysis in the soil mineral fraction testing different fractionation methods. We tested three Andosol samples from two sites of the Kohala region – Hawaii with contrasting precipitation levels. The samples tested were as follow: 1784-60, 1784-80 and 2286-50 (precipitation - average depth in cm). We performed the SOM fractionation using ultrasonic dispersion at 1500 J ml-1, wet sieving and sedimentation. The procedure was carried out in three sets: in deionized water, in 1M NaCL solution, and in polytungstate solution (SPT) 1.8 g cm-3. Six fractions were obtained as follow: free particulate organic matter (fPOM), occluded particulate organic matter (oPOM), 4000-63, 63-20, 20-2 and < 2µm, respectively. Overall, the pre-dispersion treatment with NaCL saturation did not influence the C content and its distribution, as well as the SOM composition observed by NMR and NanoSIMS analysis. The oPOM fraction revealed great differences between the contrasting samples 1784-60 and 2286-50 in C content and SOM composition. More than 90% of the soil mass was concentrated in the fractions below 20 µm. The <2µm fraction was the most representative for the evaluated Andosol, accounting with 83% of the C content and 74% of the soil mass for the three samples evaluated overall. The 2286-50 presented a higher C content than the other samples especially for fPOM and the < 2 µm fraction. The 2286-50 sample presented overall a dominance of alkyl-C, while 1784-60 showed higher amounts of carboxyl-C and O/N alkyl groups, which can be explained by differences in the mineral composition of each sample. In addition, the NanoSIMS analysis demonstrated distinct spatial differences in the distribution of 12C- and 12C14N- in organo-mineral associations at the micro scale between the two sites. The results of this study suggest that mineral interactions in the smaller size-fractions (<2µm) can be the key to explain the mechanisms of C storage in Andosols
Knudsen Effect in a Nonequilibrium Gas
From the molecular dynamics simulation of a system of hard-core disks in
which an equilibrium cell is connected with a nonequilibrium cell, it is
confirmed that the pressure difference between two cells depends on the
direction of the heat flux. From the boundary layer analysis, the velocity
distribution function in the boundary layer is obtained. The agreement between
the theoretical result and the numerical result is fairly good.Comment: 4pages, 4figure
Lagrangian Becchi-Rouet-Stora-Tyutin treatment of collective coordinates
The Becchi-Rouet-Stora-Tyutin (BRST) treatment for the quantization of
collective coordinates is considered in the Lagrangian formalism. The motion of
a particle in a Riemannian manifold is studied in the case when the classical
solutions break a non-abelian global invariance of the action. Collective
coordinates are introduced, and the resulting gauge theory is quantized in the
BRST antifield formalism. The partition function is computed perturbatively to
two-loops, and it is shown that the results are independent of gauge-fixing
parameters.Comment: LaTeX file, 26 pages, PostScript figures at end of fil
Role of Imaging in the Staging and Response Assessment of Lymphoma:Consensus of the International Conference on Malignant Lymphomas Imaging Working Group
This article comprises the consensus reached to update guidance on the use of PET-CT for staging and response assessment for 18F FDG-avid lymphomas in clinical practice and late-phase trials
Orbital Physics in the Perovskite Ti Oxides
In the perovskite Ti oxide RTiO3 (R=rare-earth ions), the Ti t2g orbitals and
spins in the 3d^1 state couple each other through the strong electron
correlations, resulting in a rich variety of orbital-spin phases. The origin
and nature of orbital-spin states of these Mott insulators have been
intensively studied. In this article, we review the studies on orbital physics
in the perovskite titanates. We focus on the following three topics: (1) the
origin and nature of the ferromagnetism as well as the orbital ordering in the
compounds with relatively small R ions such as GdTiO3 and YTiO3, (2) the origin
of the G-type antiferromagnetism and the orbital state in LaTiO3, and (3) the
orbital-spin structures in other AFM(G) compounds with relatively large R ions
(R=Ce, Pr, Nd and Sm). On the basis of these discussions, we discuss the whole
phase diagram together with mechanisms of the magnetic phase transition. We
also show that the Ti t2g degeneracy is inherently lifted in the titanates,
which allows the single-band descriptions of the ground-state and low-energy
electronic structures as a good starting point. Our analyses indicate that
these compounds offer touchstone materials described by the single-band Hubbard
model on the cubic lattice. From this insight, we also reanalyze the hole-doped
titanates. Experimentally revealed filling-dependent and bandwidth-dependent
properties and the critical behavior of the metal-insulator transitions are
discussed in the light of theories based on the single-band Hubbard models.Comment: Review article, 26 pages, to appear in New Journal of Physic
Proposal for taking data with the KLOE-2 detector at the DANE collider upgraded in energy
This document reviews the physics program of the KLOE-2 detector at
DANE upgraded in energy and provides a simple solution to run the
collider above the -peak (up to 2, possibly 2.5 GeV). It is shown how a
precise measurement of the multihadronic cross section in the energy region up
to 2 (possibly 2.5) GeV would have a major impact on the tests of the Standard
Model through a precise determination of the anomalous magnetic moment of the
muon and the effective fine-structure constant at the scale. With a
luminosity of about cms, DANE upgraded in energy
can perform a scan in the region from 1 to 2.5 GeV in one year by collecting an
integrated luminosity of 20 pb (corresponding to a few days of data
taking) for single point, assuming an energy step of 25 MeV. A few years of
data taking in this region would provide important tests of QCD and effective
theories by physics with open thresholds for pseudo-scalar (like
the ), scalar (, etc...) and axial-vector (, etc...)
mesons; vector-mesons spectroscopy and baryon form factors; tests of CVC and
searches for exotics. In the final part of the document a technical solution
for the energy upgrade of DANE is proposed.Comment: 19 pages, 8 figure
A Global Network of Science and Technology Advice in Foreign Ministries
This paper is a product of the International Dialogue on Science and Technology Advice in Foreign Ministries (Vienna Dialogue) in October 2016, involving more than twenty nations and several international organisations. The event was a key step to further develop the Foreign Minister Science and Technology Advisor Network (FMSTAN), growing from an initial group of five nations. The Vienna Dialogue was convened by the Fletcher School of Law and Diplomacy, Tufts University, and the International Institute for Applied Systems Analysis (IIASA) at the Vienna headquarters of IIASA, bringing together diplomats from foreign ministries to consider the value of evidence for informed decision-making by nations with regard to issues, impacts and resources within, across and beyond national boundaries. The evidence comes from the natural and social sciences with engineering and medicine as well as other areas of technology. By building common interests among nations, science is a tool of diplomacy, promoting cooperation and preventing conflict in our world. Science diplomacy was discussed as an international, interdisciplinary and inclusive process to help balance national interests and common interests in view of urgencies today and across generations in our globally-interconnected civilization
Dominant Negative Mutants of Bacillus thuringiensis Cry1Ab Toxin Function as Anti-Toxins: Demonstration of the Role of Oligomerization in Toxicity
BACKGROUND:Bacillus thuringiensis Cry toxins, that are used worldwide in insect control, kill insects by a mechanism that depends on their ability to form oligomeric pores that insert into the insect-midgut cells. These toxins are being used worldwide in transgenic plants or spray to control insect pests in agriculture. However, a major concern has been the possible effects of these insecticidal proteins on non-target organisms mainly in ecosystems adjacent to agricultural fields. METHODOLOGY/PRINCIPAL FINDINGS:We isolated and characterized 11 non-toxic mutants of Cry1Ab toxin affected in different steps of the mechanism of action namely binding to receptors, oligomerization and pore-formation. These mutant toxins were analyzed for their capacity to block wild type toxin activity, presenting a dominant negative phenotype. The dominant negative phenotype was analyzed at two levels, in vivo by toxicity bioassays against susceptible Manduca sexta larvae and in vitro by pore formation activity in black lipid bilayers. We demonstrate that some mutations located in helix alpha-4 completely block the wild type toxin activity at sub-stoichiometric level confirming a dominant negative phenotype, thereby functioning as potent antitoxins. CONCLUSIONS/SIGNIFICANCE:This is the first reported case of a Cry toxin dominant inhibitor. These data demonstrate that oligomerization is a fundamental step in Cry toxin action and represent a potential mechanism to protect special ecosystems from the possible effect of Cry toxins on non-target organisms
Vasodilators and low-dose acetylsalicylic acid are associated with a lower incidence of distinct primary myocardial disease manifestations in systemic sclerosis: results of the DeSScipher inception cohort study
OBJECTIVES: To investigate the influence of vasodilator drugs on the occurrence of features depending on myocardial ischaemia/fibrosis (ventricular arrhythmias, Q waves, cardiac blocks, pacemaker implantation, left ventricular ejection fraction (LVEF) <55%, and/or congestive heart failure and sudden cardiac death) in systemic sclerosis (SSc). METHODS: 601 patients with SSc were enrolled from 1 December 2012 to 30 November 2015 and had a second visit 0.5-4 years apart. 153 received no vasodilators; 448 received vasodilator therapy (ie, calcium channel blockers and/or ACE inhibitors or angiotensin II receptor blockers or combinations of them), 89 of them being also treated with either endothelin receptor antagonists or PDE5 inhibitors or prostanoids. Associations between the occurrence of myocardial disease manifestations and any demographic, disease and therapeutic aspect were investigated by Cox regression analysis. A Cox frailty survival model with centre of enrolment as random effect was performed. RESULTS: During 914 follow-up patient-years, 12 ventricular arrhythmias, 5 Q waves, 40 cardiac blocks, 6 pacemaker implantations and 19 reduced LVEF and/or congestive heart failure (CHF) occurred. In multivariate Cox regression analysis, vasodilator therapy was associated with a lower incidence of ventricular arrhythmias (p=0.03); low-dose acetylsalicylic acid (ASA) with a lower incidence of cardiac blocks and/or Q waves and/or pacemaker implantation (p=0.02); active disease with a higher incidence of LVEF <55% and/or CHF and cardiac blocks and/or Q waves and/or pacemaker implantation (p=0.05). CONCLUSIONS: The present study might suggest a preventative effect on the occurrence of distinct myocardial manifestations by vasodilator therapy and low-dose ASA
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