30,981 research outputs found
High-Fidelity Archeointensity Results for the Late Neolithic Period From Central China
Archeomagnetism focuses on exploring high-resolution variations of the geomagnetic field over hundreds to thousands of years. In this study, we carried out a comprehensive study of chronology, absolute and relative paleointensity on a late Neolithic site in central China. Ages of the samples are constrained to be ~3,500–3,000 BCE, a period when available paleointensity data are sparse. We present a total of 64 high-fidelity absolute paleointensities, demonstrating the field varied quickly from ~55 to ~90 ZAm2 between ~3,500–3,000 BCE. Our results record a new archeomagnetic jerk around 3,300 BCE, which is probably non-dipolar origin. The new results provide robust constraints on global geomagnetic models. We calculated a revised Chinese archeointensity reference curve for future application. The variations of absolute and relative paleointensity versus depth show good consistency, reinforcing the reliability of our results. This new attempt of combining absolute and relative paleointenstiy provides a useful tool for future archeomagnetic research
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A universal primer for isolation of fragments of a gene encoding phytoene desaturase for use in virus-induced gene silencing (VIGS) studies
We have been using Virus-Induced Gene Silencing (VIGS) to test the function of genes that are candidates for involvement in floral senescence. Although VIGS is a powerful tool for assaying the effects of gene silencing in plants, relatively few taxa have been studied using this approach, and most that have are in the Solanaceae. We typically use silencing of phytoene desaturase (PDS) in preliminary tests of the feasibility of using VIGS. Silencing this gene, whose product is involved in carotene biosynthesis, results in a characteristic photobleaching phenotype in the leaves. We have found that efficient silencing requires the use of fragments that are more than 90% homologous to the target gene. To simplify testing the effectiveness of VIGS in a range of species, we designed a set of universal primers to a region of the PDS gene that is highly conserved among species, and that therefore allows an investigator to isolate a fragment of the homologous PDS gene from the species of interest. We report the sequences of these primers and the results of VIGS experiments in horticultural species from the Asteraceae, Leguminosae, Balsaminaceae and Solanaceae
Testable two-loop radiative neutrino mass model based on an effective operator
A new two-loop radiative Majorana neutrino mass model is constructed from the
gauge-invariant effective operator that violates lepton number conservation by two units. The
ultraviolet completion features two scalar leptoquark flavors and a color-octet
Majorana fermion. We show that there exists a region of parameter space where
the neutrino oscillation data can be fitted while simultaneously meeting
flavor-violation and collider bounds. The model is testable through lepton
flavor-violating processes such as , , and
conversion, as well as collider searches for the scalar
leptoquarks and color-octet fermion. We computed and compiled a list of
necessary Passarino-Veltman integrals up to boxes in the approximation of
vanishing external momenta and made them available as a Mathematica package,
denoted as ANT.Comment: 42 pages, 11 figures, typo in Eq. (4.9) as well as wrong chirality
structures in Secs. 4.5 and 5.2 corrected, final results unchange
The Cardy-Verlinde formula and entropy of Topological Reissner-Nordstr\"om black holes in de Sitter spaces
In this paper we discuss the question of whether the entropy of cosmological
horizon in Topological Reissner-Nordstr\"om- de Sitter spaces can be described
by the Cardy-Verlinde formula, which is supposed to be an entropy formula of
conformal field theory in any dimension. Furthermore, we find that the entropy
of black hole horizon can also be rewritten in terms of the Cardy-Verlinde
formula for these black holes in de Sitter spaces, if we use the definition due
to Abbott and Deser for conserved charges in asymptotically de Sitter spaces.
Our result is in favour of the dS/CFT correspondence.Comment: 6 pages, accepted for publication in IJMP
Modeling Uncertainty in Large Natural Resource Allocation Problems
The productivity of the world's natural resources is critically dependent on a variety of highly uncertain factors, which obscure individual investors and governments that seek to make long-term, sometimes irreversible investments in their exploration and utilization. These dynamic considerations are poorly represented in disaggregated resource models, as incorporating uncertainty into large-dimensional problems presents a challenging computational task. This study introduces a novel numerical method to solve large-scale dynamic stochastic natural resource allocation problems that cannot be addressed by conventional methods. The method is illustrated with an application focusing on the allocation of global land resource use under stochastic crop yields due to adverse climate impacts and limits on further technological progress. For the same model parameters, the range of land conversion is considerably smaller for the dynamic stochastic model as compared to deterministic scenario analysis. The scenario analysis can thus significantly overstate the magnitude of expected land conversion under uncertain crop yields
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