122 research outputs found
Dimension Reduction for Efficient Data-Enabled Predictive Control
The recent data-enabled predictive control (DeePC) paradigm directly utilizes
offline input/output data from an unknown system to predict its future
trajectory and compute optimal control inputs online. In this scheme, the
pre-collected input/output data needs to be sufficiently rich to represent the
system behavior. This generally leads to an excessive amount of offline data,
which consequently results in a high-dimension optimization problem in online
predictive control. In this paper, we propose a simple yet effective singular
value decomposition (SVD) based strategy to reduce the optimization problem
dimension in DeePC. Specifically, in the case of linear time-invariant systems,
the excessive input/output measurements can be rearranged into a smaller data
library for the non-parametric representation of system behavior. Based on this
observation, we use an SVD-based strategy to pre-process the offline data that
achieves dimension reduction in DeePC. Numerical experiments confirm that the
proposed method significantly enhances the computation efficiency without
compromising the control performance.Comment: 9 pages, 4 figure
Frustrated magnetic interactions in a Wigner-Mott insulator
Two-dimensional semiconductor moir\'e materials have emerged as a highly
controllable platform to simulate and explore quantum condensed matter.
Compared to real solids, electrons in semiconductor moir\'e materials are less
strongly attracted to the moir\'e lattice sites, making the nonlocal
contributions to the magnetic interactions as important as the Anderson
super-exchange. It provides a unique platform to study the effects of competing
magnetic interactions. Here, we report the observation of strongly frustrated
magnetic interactions in a Wigner-Mott insulating state at 2/3 filling of the
moir\'e lattice in angle-aligned WSe2/WS2 heterobilayers. Magneto-optical
measurements show that the net exchange interaction is antiferromagnetic for
filling factors below 1 with a strong suppression at 2/3 filling. The
suppression is lifted upon screening of the long-range Coulomb interactions and
melting of the Wigner-Mott insulator by a nearby metallic gate. The results can
be qualitatively captured by a honeycomb-lattice spin model with an
antiferromagnetic nearest-neighbor coupling and a ferromagnetic second-neighbor
coupling. Our study establishes semiconductor moir\'e materials as a model
system for the lattice-spin physics and frustrated magnetism
Knowledge Domains and Emerging Trends of Osteoblasts-Osteoclasts in Bone Disease From 2002 to 2021: A Bibliometrics Analysis and Visualization Study
BackgroundOsteoblasts-Osteoclasts has been a major area in bone disease research for a long time. However, there are few systematic studies in this field using bibliometric analysis. We aimed to perform a bibliometric analysis and visualization study to determine hotspots and trends of osteoblasts-osteoclasts in bone diseases, identify collaboration and influence among authors, countries, institutions, and journals, and assess the knowledge base to develop basic and clinical research in the future.MethodsWe collected articles and reviews for osteoblasts-osteoclasts in bone diseases from the Web of Science Core Collection. In addition, we utilized scientometrics software (CiteSpace5.8 and VOSviewer1.6.18) for visual analysis of countries/regions, institutions, authors, references, and keywords in the field.ResultsIn total, 16,832 authors from 579 institutions in 73 countries/regions have published 3,490 papers in 928 academic journals. The literature in this field is rapidly increasing, with Bone publishing the most articles, whereas Journal of Bone and Mineral Research had the most co-cited journals. These two journals mainly focused on molecular biology and the clinical medicine domain. The countries with the highest number of publications were the US and China, and the University of Arkansas for Medical Sciences was the most active institution. Regarding authors, Stavros C. Manolagas published the most articles, and Hiroshi Takayanagi had the most co-cited papers. Research in this field mainly includes molecular expression and regulatory mechanisms, differentiation, osteoprotection, inflammation, and tumors. The latest research hotspots are oxidative stress, mutation, osteocyte formation and absorption, bone metabolism, tumor therapy, and in-depth mechanisms.ConclusionWe identified the research hotspots and development process of osteoblasts-osteoclasts in bone disease using bibliometric and visual methods. Osteoblasts-osteoclasts have attracted increasing attention in bone disease. This study will provide a valuable reference for researchers concerned with osteoblasts-osteoclasts in bone diseases
Functional connectivity of the human amygdala in health and in depression
To analyze the functioning of the amygdala in depression, we performed the first voxel-level resting state functional-connectivity neuroimaging analysis of depression of voxels in the amygdala with all other voxels in the brain, with 336 patients with major depressive disorder and 350 controls. Amygdala voxels had decreased functional connectivity with the orbitofrontal cortex, temporal lobe areas, including the temporal pole, inferior temporal gyrus, and the parahippocampal gyrus. The reductions in the strengths of the functional connectivity of the amygdala voxels with the medial orbitofrontal cortex and temporal lobe voxels were correlated with increases in the Beck Depression Inventory score and in the duration of illness measures of depression. Parcellation analysis in 350 healthy controls based on voxel-level functional connectivity showed that the basal division of the amygdala has high functional connectivity with medial orbitofrontal cortex areas, and the dorsolateral amygdala has strong functional connectivity with the lateral orbitofrontal cortex and related ventral parts of the inferior frontal gyrus. In depression, the basal amygdala division had especially reduced functional connectivity with the medial orbitofrontal cortex which is involved in reward; and the dorsolateral amygdala subdivision had relatively reduced functional connectivity with the lateral orbitofrontal cortex which is involved in non-reward
Colorimetric Assay for Determination of Lead (II) Based on Its Incorporation into Gold Nanoparticles during Their Synthesis
In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle formation. Analysis of Pb2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb2+ can be realized. As the Pb2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (Δλ) and logarithm of Pb2+ concentration ranging from 5.0 × 10−8 to 1.0 × 10−6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb2+ detection with a low detection limit down to 2.5 × 10−8 M
- …