152 research outputs found
Magnetic instability and spin-glass order beyond the Anderson-Mott transition in interacting power-law random banded matrix fermions
In the presence of quenched disorder, the competition between local
magnetic-moment formation and Anderson localization for electrons at a
zero-temperature, metal-insulator transition (MIT) remains a long unresolved
problem. Here, we study the interplay of these ingredients in a power-law
random banded matrix model of spin-1/2 fermions with repulsive Hubbard
interactions. Focusing on the regime of weak interactions, we perform both
analytical field theory and numerical self-consistent Hartree-Fock numerical
calculations. We show that interference-mediated effects strongly enhance the
density of states and magnetic fluctuations upon approaching the MIT from the
metallic side. These are consistent with results due to Finkel'stein obtained
four decades ago. Our numerics further show that local moments nucleate from
typical states at the Fermi energy near the MIT, with a density that grows
continuously into the insulating phase. We identify spin-glass order in the
insulator by computing the overlap distribution between converged Hartree-Fock
mean-field moment profiles. Our results indicate that itinerant interference
effects can morph smoothly into moment formation and magnetic frustration
within a single model, revealing a common origin for these disparate phenomena.Comment: 21 pages, 18 figure
Enhanced Amplitude for Superconductivity due to Spectrum-wide Wave Function Criticality in Quasiperiodic and Power-law Random Hopping Models
We study the interplay of superconductivity and a wide spectrum of critical
(multifractal) wave functions ("spectrum-wide quantum criticality," SWQC) in
the one-dimensional Aubry-Andr\'e and power-law random-banded matrix models
with attractive interactions, using self-consistent BCS theory. We find that
SWQC survives the incorporation of attractive interactions at the Anderson
localization transition, while the pairing amplitude is maximized near this
transition in both models. Our results suggest that SWQC, recently discovered
in two-dimensional topological surface-state and nodal superconductor models,
can robustly enhance superconductivity.Comment: 8+9 pages, 4+13 figures; v2: added superfluid stiffness result
Gob Spontaneous Combustion in a Fully Mechanized Long-wall Top-Coal Caving Face
Geological conditions allow, underground coal mines in China tend to use comprehensively mechanized roof-coal caving technique in an effort to gain a higher degree of mechanization at coal faces as well as higher coal production rates. As a face advances, a large amount of coal will be left behind in its gob area which may experience a self-enhancing process of coal oxidation and heat accumulation, ultimately leading to open fire. Such a self-enhancing coal spontaneous combustion process is a significantly impeding mine safety and productivity. A sound mathematical model is an important step to predict the probability of spontaneous combustion so that measures against coal self-heating can be adopted in time and at comparatively low cost. This paper analyzes main factors in coal spontaneous combustion process and proposes a mathematical model to describe the dynamic process of coal self-heating in the gob. This model has been applied to a coal production face in Datong Coal Region in Shangdong Province to satisfactorily predict the spontaneous combustion probability
Metabolomics and Transcriptomics Reveal the Response Mechanisms of Mikania micrantha to Puccinia spegazzinii Infection
Mikania micrantha is one of the worst invasive species globally and can cause significant negative impacts on agricultural and forestry economics, particularly in Asia and the Pacific region. The rust Puccinia spegazzinii has been used successfully as a biological control agent in several countries to help manage M. micrantha. However, the response mechanisms of M. micrantha to P. spegazzinii infection have never been studied. To investigate the response of M. micrantha to infection by P. spegazzinii, an integrated analysis of metabolomics and transcriptomics was performed. The levels of 74 metabolites, including organic acids, amino acids, and secondary metabolites in M. micrantha infected with P. spegazzinii, were significantly different compared to those in plants that were not infected. After P. spegazzinii infection, the expression of the TCA cycle gene was significantly induced to participate in energy biosynthesis and produce more ATP. The content of most amino acids, such as L-isoleucine, L-tryptophan and L-citrulline, increased. In addition, phytoalexins, such as maackiain, nobiletin, vasicin, arachidonic acid, and JA-Ile, accumulated in M. micrantha. A total of 4978 differentially expressed genes were identified in M. micrantha infected by P. spegazzinii. Many key genes of M. micrantha in the PTI (pattern-triggered immunity) and ETI (effector-triggered immunity) pathways showed significantly higher expression under P. spegazzinii infection. Through these reactions, M. micrantha is able to resist the infection of P. spegazzinii and maintain its growth. These results are helpful for us to understand the changes in metabolites and gene expression in M. micrantha after being infected by P. spegazzinii. Our results can provide a theoretical basis for weakening the defense response of M. micrantha to P. spegazzinii, and for P. spegazzinii as a long-term biological control agent of M. micrantha
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