1,089 research outputs found
Dynamic Power Spectral Analysis of Solar Measurements from Photospheric, Chromospheric, and Coronal Sources
An important aspect in the power spectral analysis of solar variability is the quasistationary and quasiperiodic nature of solar periodicities. In other words, the frequency, phase, and amplitude of solar periodicities vary on time scales ranging from active region lifetimes to solar cycle time scales. Here, researchers employ a dynamic, or running, power spectral density analysis to determine many periodicities and their time-varying nature in the projected area of active sunspot groups (S sub act). The Solar Maximum Mission/Active Cavity Radiometer Irradiance Monitor (SMM/ACRIM) total solar irradiance (S), the Nimbus-7 MgII center-to-wing ratio (R (MgII sub c/w)), the Ottawa 10.7 cm flux (F sub 10.7), and the GOES background x ray flux (X sub b) for the maximum, descending, and minimum portions of solar cycle 21 (i.e., 1980 to 1986) are used. The technique dramatically illustrates several previously unrecognized periodicities. For example, a relatively stable period at about 51 days has been found in those indices which are related to emerging magnetic fields. The majority of solar periodicities, particularly around 27, 150 and 300 days, are quasiperiodic because they vary in amplitude and frequency throughout the solar cycle. Finally, it is shown that there are clear differences between the power spectral densities of solar measurements from photospheric, chromospheric, and coronal sources
Comment on ’Winding around non-Hermitian singularities’ by Zhong et al., Nat. Commun. 9, 4808 (2018)
A unified view on geometric phases and exceptional points in adiabatic quantum mechanics
We present a formal geometric framework for the study of adiabatic quantum
mechanics for arbitrary finite-dimensional non-degenerate Hamiltonians. This
framework generalizes earlier holonomy interpretations of the geometric phase
to non-cyclic states appearing for non-Hermitian Hamiltonians. We start with an
investigation of the space of non-degenerate operators on a finite-dimensional
state space. We then show how the energy bands of a Hamiltonian family form a
covering space. Likewise, we show that the eigenrays form a bundle, a
generalization of a principal bundle, which admits a natural connection
yielding the (generalized) geometric phase. This bundle provides in addition a
natural generalization of the quantum geometric tensor and derived tensors, and
we show how it can incorporate the non-geometric dynamical phase as well. We
finish by demonstrating how the bundle can be recast as a principal bundle, so
that both the geometric phases and the permutations of eigenstates can be
expressed simultaneously by means of standard holonomy theory
Numerical study of SU(2) Yang-Mills theory with gluinos
We report on a numerical investigation of the SU(2) gauge theory with
gluinos.
The low-lying spectrum in bosonic and fermionic channels is determined.
Improvements of the multi-bosonic algorithm are discussed.Comment: latex, 3 pages, 4 figures; Poster presented by K. Spanderen at
LATTICE9
Solution of gauge theories induced by fundamental representation scalars
Gauge theories induced by scalars in the fundamental representation of the
group are investigated in the large
and limit. A master field is defined from bilinears of the scalar
field following an Eguchi-Kawai type reduction of spacetime. The density
function for the master field satisfies an integral equation that can be solved
exactly in two dimensions (D=2) and in a convergent series of approximations at
. While at D=2 the system is in the same phase at all ,
it undergoes a phase transition at a critical value, , for
.Comment: 12 pages, LaTe
Prospects for Improving Alfalfa Yield Using Genomic- and Phenomic-Based Breeding
Alfalfa (Medicago sativa L.) is a perennial outcrossing legume that is cultivated as an important forage crop in many parts of the world. Yield is the most important trait for profitable alfalfa production, yet over the last 30 years yield improvement in California has stagnated. Current breeding methods focus on recurrent phenotypic selection; however, alternatives incorporating genomic- and phenomic-based information may enhance genetic gain and help to address the lack of yield improvement. Here we attempt to increase the yield potential of alfalfa using genomic selection (GS) in combination with high throughput phenotyping (HTP). A total of 193 families from two closely related elite populations were sown in the greenhouse and transplanted into mini sward plots at two locations near Davis, CA in May 2020. The trial was managed as a high-input system under full irrigation. Families were genotyped and phenotyped for biomass yield by mechanical harvest and a combination of drone and tower-based remote sensors across 12 harvests, 3 in the establishment year (2020), 7 in the first full year of production (2021) and 2 in 2022. Alfalfa yields ranged from 13-27 tonnes DM/hectare/year with a number of half-sib families outperforming popular cultivars in the first 2 years of production. Biomass volume predicted from the drone-based cameras had a moderate prediction accuracy with an overall R2 of 0.55. Some individual harvests reached accuracies as high as 0.85. Genotyping resulted in a dataset with 6,838 SNPs. Allele frequencies were used to generate a relationship matrix for GS. Narrow-sense heritability for dry matter yield was 0.31 and the predictive ability of the GS model was 0.15
A q-deformed nonlinear map
A scheme of q-deformation of nonlinear maps is introduced. As a specific
example, a q-deformation procedure related to the Tsallis q-exponential
function is applied to the logistic map. Compared to the canonical logistic
map, the resulting family of q-logistic maps is shown to have a wider spectrum
of interesting behaviours, including the co-existence of attractors -- a
phenomenon rare in one dimensional maps.Comment: 17 pages, 19 figure
Antibody-mediated inhibition of syndecan-4 dimerisation reduces interleukin (IL)-1 receptor trafficking and signalling.
OBJECTIVE: Syndecan-4 (sdc4) is a cell-anchored proteoglycan that consists of a transmembrane core protein and glucosaminoglycan (GAG) side chains. Binding of soluble factors to the GAG chains of sdc4 may result in the dimerisation of sdc4 and the initiation of downstream signalling cascades. However, the question of how sdc4 dimerisation and signalling affects the response of cells to inflammatory stimuli is unknown. METHODS: Sdc4 immunostaining was performed on rheumatoid arthritis (RA) tissue sections. Interleukin (IL)-1 induced extracellular signal-regulated kinases (ERK) phosphorylation and matrix metalloproteinase-3 production was investigated. Il-1 binding to sdc4 was investigated using immunoprecipitation. IL-1 receptor (IL1R1) staining on wild-type, sdc4 and IL1R1 knockout fibroblasts was performed in fluorescence-activated cell sorting analyses. A blocking sdc4 antibody was used to investigate sdc4 dimerisation, IL1R1 expression and the histological paw destruction in the human tumour necrosis factor-alpha transgenic mouse. RESULTS: We show that in fibroblasts, the loss of sdc4 or the antibody-mediated inhibition of sdc4 dimerisation reduces the cell surface expression of the IL-1R and regulates the sensitivity of fibroblasts to IL-1. We demonstrate that IL-1 directly binds to sdc4 and in an IL-1R-independent manner leads to its dimerisation. IL-1-induced dimerisation of sdc4 regulates caveolin vesicle-mediated trafficking of the IL1R1, which in turn determines the responsiveness to IL-1. Administration of antibodies (Ab) against the dimerisation domain of sdc4, thus, strongly reduces the expression IL1R1 on arthritic fibroblasts both in vitro and an animal model of human RA. CONCLUSION: Collectively, our data suggest that Ab that specifically inhibit sdc4 dimerisation may support anti-IL-1 strategies in diseases such as inflammatory arthritis
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