8,006 research outputs found
Designing defect-based qubit candidates in wide-gap binary semiconductors for solid-state quantum technologies
The development of novel quantum bits is key to extend the scope of
solid-state quantum information science and technology. Using first-principles
calculations, we propose that large metal ion - vacancy complexes are promising
qubit candidates in two binary crystals: 4H-SiC and w-AlN. In particular, we
found that the formation of neutral Hf- and Zr-vacancy complexes is
energetically favorable in both solids; these defects have spin-triplet ground
states, with electronic structures similar to those of the diamond NV center
and the SiC di-vacancy. Interestingly, they exhibit different spin-strain
coupling characteristics, and the nature of heavy metal ions may allow for easy
defect implantation in desired lattice locations and ensure stability against
defect diffusion. In order to support future experimental identification of the
proposed defects, we report predictions of their optical zero-phonon line,
zero-field splitting and hyperfine parameters. The defect design concept
identified here may be generalized to other binary semiconductors to facilitate
the exploration of new solid-state qubits.Comment: 23 pages, 5 figures, 6 tables, Supplementary Information is added at
the en
The Recovery of Weak Impulsive Signals Based on Stochastic Resonance and Moving Least Squares Fitting
In this paper a stochastic resonance (SR)-based method for recovering weak impulsive signals is developed for quantitative diagnosis of faults in rotating machinery. It was shown in theory that weak impulsive signals follow the mechanism of SR, but the SR produces a nonlinear distortion of the shape of the impulsive signal. To eliminate the distortion a moving least squares fitting method is introduced to reconstruct the signal from the output of the SR process. This proposed method is verified by comparing its detection results with that of a morphological filter based on both simulated and experimental signals. The experimental results show that the background noise is suppressed effectively and the key features of impulsive signals are reconstructed with a good degree of accuracy, which leads to an accurate diagnosis of faults in roller bearings in a run-to failure test
A Revisit to the Normalized Eight-Point Algorithm and A Self-Supervised Deep Solution
The Normalized Eight-Point algorithm has been widely viewed as the
cornerstone in two-view geometry computation, where the seminal Hartley's
normalization greatly improves the performance of the direct linear
transformation (DLT) algorithm. A natural question is, whether there exists and
how to find other normalization methods that may further improve the
performance as per each input sample. In this paper, we provide a novel
perspective and make two contributions towards this fundamental problem: 1) We
revisit the normalized eight-point algorithm and make a theoretical
contribution by showing the existence of different and better normalization
algorithms; 2) We present a deep convolutional neural network with a
self-supervised learning strategy to the normalization. Given eight pairs of
correspondences, our network directly predicts the normalization matrices, thus
learning to normalize each input sample. Our learning-based normalization
module could be integrated with both traditional (e.g., RANSAC) and deep
learning framework (affording good interpretability) with minimal efforts.
Extensive experiments on both synthetic and real images show the effectiveness
of our proposed approach.Comment: 12 pages, 7 figures, A preliminary versio
A performance comparison of the contiguous allocation strategies in 3D mesh connected multicomputers
The performance of contiguous allocation strategies can be significantly affected by the distribution of job execution times. In this paper, the performance of the existing contiguous allocation strategies for 3D mesh multicomputers is re-visited in the context of heavy-tailed distributions (e.g., a Bounded Pareto distribution). The strategies are evaluated and compared using simulation experiments for both First-Come-First-Served (FCFS) and Shortest-Service-Demand (SSD) scheduling strategies under a variety of system loads and system sizes. The results show that the performance of the allocation strategies degrades considerably when job execution times follow a heavy-tailed distribution. Moreover, SSD copes much better than FCFS scheduling strategy in the presence of heavy-tailed job execution times. The results also show that the strategies that depend on a list of allocated sub-meshes for both allocation and deallocation have lower allocation overhead and deliver good system performance in terms of average turnaround time and mean system utilization
Observation of superradiance in a phase fluctuating dipolar Bose-Einstein condensate
Despite the extensive study of matter-wave superradiance in a Bose-Einstein
condensate (BEC) using its unique coherence property, the controllability of
superradiant process has remained limited in the previous studies exploiting a
phase-coherent condensate with isotropic contact interactions. Here, we combine
tunable s-wave scattering with dipolar interactions in a BEC of Er
atoms wherein the asymmetry and threshold of superradiance are independently
controlled. By changing the s-wave scattering length near the Feshbach
resonance, we tune the superradiance threshold with increasing phase
fluctuations. In contrast to collective light scattering from a condensate only
with contact interactions, we observe an asymmetric superradiant peak in a
dipolar BEC by changing the direction of external magnetic field. This results
from the anisotropic excitation spectrum induced by the dipole-dipole
interaction. Our observation is expected to bring forth unprecedented
application of matter-wave optics leading to controlled emission of matter
wave.Comment: 6 pages, 6 figure
Data-enabled Field Experiment Planning, Management, And Research Using Cyberinfrastructure
In the spring of 2013, NASA conducted a field campaign known as Iowa Flood Studies (IFloodS) as part of the Ground Validation (GV) program for the Global Precipitation Measurement (GPM) mission. The purpose of IFloodS was to enhance the understanding of flood-related, space-based observations of precipitation processes in events that transpire worldwide. NASA used a number of scientific instruments such as ground based weather radars, rain and soil moisture gauges, stream gauges, and disdrometers to monitor rainfall events in Iowa. This article presents the cyberinfrastructure tools and systems that supported the planning, reporting, and management of the field campaign and that allow these data and models to be accessed, evaluated, and shared for research. The authors describe the collaborative informatics tools, which are suitable for the network design, that were used to select the locations in which to place the instruments. How the authors used information technology tools for instrument monitoring, data acquisition, and visualizations after deploying the instruments and how they used a different set of tools to support data analysis and modeling after the campaign are also explained. All data collected during the campaign are available through the Global Hydrology Resource Center (GHRC), a NASA Distributed Active Archive Center (DAAC)
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CRISPRi-based radiation modifier screen identifies long non-coding RNA therapeutic targets in glioma.
BackgroundLong non-coding RNAs (lncRNAs) exhibit highly cell type-specific expression and function, making this class of transcript attractive for targeted cancer therapy. However, the vast majority of lncRNAs have not been tested as potential therapeutic targets, particularly in the context of currently used cancer treatments. Malignant glioma is rapidly fatal, and ionizing radiation is part of the current standard-of-care used to slow tumor growth in both adult and pediatric patients.ResultsWe use CRISPR interference (CRISPRi) to screen 5689 lncRNA loci in human glioblastoma (GBM) cells, identifying 467 hits that modify cell growth in the presence of clinically relevant doses of fractionated radiation. Thirty-three of these lncRNA hits sensitize cells to radiation, and based on their expression in adult and pediatric gliomas, nine of these hits are prioritized as lncRNA Glioma Radiation Sensitizers (lncGRS). Knockdown of lncGRS-1, a primate-conserved, nuclear-enriched lncRNA, inhibits the growth and proliferation of primary adult and pediatric glioma cells, but not the viability of normal brain cells. Using human brain organoids comprised of mature neural cell types as a three-dimensional tissue substrate to model the invasive growth of glioma, we find that antisense oligonucleotides targeting lncGRS-1 selectively decrease tumor growth and sensitize glioma cells to radiation therapy.ConclusionsThese studies identify lncGRS-1 as a glioma-specific therapeutic target and establish a generalizable approach to rapidly identify novel therapeutic targets in the vast non-coding genome to enhance radiation therapy
O Parque Augusta e a multiplicação do potencial construtivo: a TDC para a implantação de Parques Municipais no PDE-SP de 2014
The Transfer of Building Rights (TDC) is an urban policy instrument which allows the transfer or alienates the right to build of a property with public interest. In the City of SĂŁo Paulo, the TDC for Public Parks has strike attention, especially after its use in the agreement regarding Parque Augusta between City Hall, Public Ministry, civil society, and the construction companies Cyrela and Setin. This article aims to analyze the transfers from the Declarations of Transferable Construction Potential issued to the lands of Parque Augusta. For this, based on the data collected up to July 2020, the study carried out TDC simulations for the parks of the city of SĂŁo Paulo in order to show the exacerbated multiplication of construction potential resulting from this modality. It also points out the possible effects of such multiplication and indicates the legal provisions that led to such distortion, exclusive of the TDC modality for Municipal Parks.A TransferĂŞncia do Direito de Construir (TDC) Ă© um instrumento urbanĂstico que permite a transferĂŞncia ou a alienação do potencial construtivo de um imĂłvel munido de interesse pĂşblico. No municĂpio de SĂŁo Paulo, a modalidade de TDC para a implantação de Parques Municipais tem chamado atenção, especialmente apĂłs sua utilização no acordo a respeito do Parque Augusta firmado entre prefeitura, MinistĂ©rio PĂşblico, sociedade civil e as construtoras Cyrela e Setin. O presente artigo tem como objetivo analisar as transferĂŞncias realizadas como resultado das Declarações de Potencial Construtivo PassĂvel de TransferĂŞncia emitidas para os terrenos do Parque Augusta. Para isso, com base nos dados coletados atĂ© julho de 2020, o estudo realizou simulações de TDC para os parques da cidade de SĂŁo Paulo a fim de evidenciar a multiplicação exacerbada de potencial construtivo decorrente da modalidade, bem como para apontar os possĂveis efeitos dessa multiplicação e indicar as disposições legais que geraram tal distorção, exclusiva da modalidade de TDC para Parques Municipais
A tachyonic scalar field with mutually interacting components
We investigate the tachyonic cosmological potential in two
different cases of the quasi-exponential expansion of universe and discuss
various forms of interaction between the two components---matter and the
cosmological constant--- of the tachyonic scalar field, which leads to the
viable solutions of their respective energy densities. The distinction among
the interaction forms is shown to appear in the diagnostic. Further,
the role of the high- and low-redshift observations of the Hubble parameter is
discussed to determine the proportionality constants and hence the correct form
of matter--cosmological constant interaction.Comment: 14 page
Superconductivity at the Border of Electron Localization and Itinerancy
The superconducting state of iron pnictides and chalcogenides exists at the
border of antiferromagnetic order. Consequently, these materials could provide
clues about the relationship between magnetism and unconventional
superconductivity. One explanation, motivated by the so-called bad-metal
behaviour of these materials, proposes that magnetism and superconductivity
develop out of quasi-localized magnetic moments which are generated by strong
electron-electron correlations. Another suggests that these phenomena are the
result of weakly interacting electron states that lie on nested Fermi surfaces.
Here we address the issue by comparing the newly discovered alkaline iron
selenide superconductors, which exhibit no Fermi-surface nesting, to their iron
pnictide counterparts. We show that the strong-coupling approach leads to
similar pairing amplitudes in these materials, despite their different Fermi
surfaces. We also find that the pairing amplitudes are largest at the boundary
between electronic localization and itinerancy, suggesting that new
superconductors might be found in materials with similar characteristics.Comment: Version of the published manuscript prior to final journal-editting.
Main text (23 pages, 4 figures) + Supplementary Information (14 pages, 7
figures, 3 tables). Calculation on the single-layer FeSe is added.
Enhancement of the pairing amplitude in the vicinity of the Mott transition
is highlighted. Published version is at
http://www.nature.com/ncomms/2013/131115/ncomms3783/full/ncomms3783.htm
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