84 research outputs found
Angle-resolved broadband ferromagnetic resonance apparatus enabled through a spring-loaded sample mounting manipulator
Broadband ferromagnetic resonance is a useful technique to determine the
magnetic anisotropy and study the magnetization dynamics of magnetic thin
films. We report a spring-loaded sample loading manipulator for reliable sample
mounting and rotation. The manipulator enables maximum signal, enhances system
stability and is particularly useful for fully automated in-plane-field
angle-resolved measurements. This angle-resolved broadband ferromagnetic
resonance apparatus provides a viable method to study anisotropic damping and
weak magnetic anisotropies, both vital for fundamental research and
applications.Comment: 11pages,4 figure
Magnetization dynamics and its scattering mechanism in thin CoFeB films with interfacial anisotropy
Studies of magnetization dynamics have incessantly facilitated the discovery
of fundamentally novel physical phenomena, making steady headway in the
development of magnetic and spintronics devices. The dynamics can be induced
and detected electrically, offering new functionalities in advanced electronics
at the nanoscale. However, its scattering mechanism is still disputed.
Understanding the mechanism in thin films is especially important, because most
spintronics devices are made from stacks of multilayers with nanometer
thickness. The stacks are known to possess interfacial magnetic anisotropy, a
central property for applications, whose influence on the dynamics remains
unknown. Here, we investigate the impact of interfacial anisotropy by adopting
CoFeB/MgO as a model system. Through systematic and complementary measurements
of ferromagnetic resonance (FMR), on a series of thin films, we identify
narrower FMR linewidths at higher temperatures. We explicitly rule out the
temperature dependence of intrinsic damping as a possible cause, and it is also
not expected from existing extrinsic scattering mechanisms for ferromagnets. We
ascribe this observation to motional narrowing, an old concept so far neglected
in the analyses of FMR spectra. The effect is confirmed to originate from
interfacial anisotropy, impacting the practical technology of spin-based
nanodevices up to room temperature.Comment: 23 pages,3 figure
Interaction analysis under misspecification of main effects: Some common mistakes and simple solutions
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154951/1/sim8505_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154951/2/sim8505.pd
MusicAgent: An AI Agent for Music Understanding and Generation with Large Language Models
AI-empowered music processing is a diverse field that encompasses dozens of
tasks, ranging from generation tasks (e.g., timbre synthesis) to comprehension
tasks (e.g., music classification). For developers and amateurs, it is very
difficult to grasp all of these task to satisfy their requirements in music
processing, especially considering the huge differences in the representations
of music data and the model applicability across platforms among various tasks.
Consequently, it is necessary to build a system to organize and integrate these
tasks, and thus help practitioners to automatically analyze their demand and
call suitable tools as solutions to fulfill their requirements. Inspired by the
recent success of large language models (LLMs) in task automation, we develop a
system, named MusicAgent, which integrates numerous music-related tools and an
autonomous workflow to address user requirements. More specifically, we build
1) toolset that collects tools from diverse sources, including Hugging Face,
GitHub, and Web API, etc. 2) an autonomous workflow empowered by LLMs (e.g.,
ChatGPT) to organize these tools and automatically decompose user requests into
multiple sub-tasks and invoke corresponding music tools. The primary goal of
this system is to free users from the intricacies of AI-music tools, enabling
them to concentrate on the creative aspect. By granting users the freedom to
effortlessly combine tools, the system offers a seamless and enriching music
experience
Neutrophils Compromise Retinal Pigment Epithelial Barrier Integrity
We hypothesized that neutrophils and their secreted factors mediate breakdown of the integrity of the outer blood-retina-barrier by degrading the apical tight junctions of the retinal pigment epithelium (RPE). The effect of activated neutrophils or neutrophil cell lysate on apparent permeability of bovine RPE-Choroid explants was evaluated by measuring [3H] mannitol flux in a modified Ussing chamber. The expression of matrix metalloproteinase- (MMP-) 9 in murine peritoneal neutrophils, and the effects of neutrophils on RPE tight-junction protein expression were assessed by confocal microscopy and western blot. Our results revealed that basolateral incubation of explants with neutrophils decreased occludin and ZO-1 expression at 1 and 3 hours and increased the permeability of bovine RPE-Choroid explants by >3-fold (P < .05). Similarly, basolateral incubation of explants with neutrophil lysate decreased ZO-1 expression at 1 and 3 hours (P < .05) and increased permeability of explants by 75%. Further, we found that neutrophils prominently express MMP-9 and that incubation of explants with neutrophils in the presence of anti-MMP-9 antibody inhibited the increase in permeability. These data suggest that neutrophil-derived MMP-9 may play an important role in disrupting the integrity of the outer blood-retina barrier
Microwave resonances of magnetic skyrmions in thin film multilayers
Non-collinear magnets exhibit a rich array of dynamic properties at microwave frequencies. They can host nanometre-scale topological textures known as skyrmions, whose spin resonances are expected to be highly sensitive to their local magnetic environment. Here, we report a magnetic resonance study of an [Ir/Fe/Co/Pt] multilayer hosting Néel skyrmions at room temperature. Experiments reveal two distinct resonances of the skyrmion phase during in-plane ac excitation, with frequencies between 6–12 GHz. Complementary micromagnetic simulations indicate that the net magnetic dipole moment rotates counterclockwise (CCW) during both resonances. The magnon probability distribution for the lower-frequency resonance is localised within isolated skyrmions, unlike the higher-frequency mode which principally originates from areas between skyrmions. However, the properties of both modes depend sensitively on the out-of-plane dipolar coupling, which is controlled via the ferromagnetic layer spacing in our heterostructures. The gyrations of stable isolated skyrmions reported in this room temperature study encourage the development of new material platforms and applications based on skyrmion resonances. Moreover, our material architecture enables the resonance spectra to be tuned, thus extending the functionality of such applications over a broadband frequency range
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Abnormal Voxel-Wise Degree Centrality in Patients With Late-Life Depression: A Resting-State Functional Magnetic Resonance Imaging Study.
Objectives:Late-life depression (LLD) has negative impacts on somatic, emotional and cognitive domains of the lives of patients. Elucidating the abnormality in the brain networks of LLD patients could help to strengthen the understanding of LLD pathophysiology, however, the studies exploring the spontaneous brain activity in LLD during the resting state remain limited. This study aimed at identifying the voxel-level whole-brain functional connectivity changes in LLD patients. Methods:Fifty patients with late-life depression (LLD) and 33 healthy controls were recruited. All participants underwent a resting-state functional magnetic resonance imaging scan to assess the voxel-wise degree centrality (DC) changes in the patients. Furthermore, DC was compared between two patient subgroups, the late-onset depression (LOD) and the early-onset depression (EOD). Results:Compared with the healthy controls, LLD patients showed increased DC in the inferior parietal lobule, parahippocampal gyrus, brainstem and cerebellum (p < 0.05, AlphaSim-corrected). LLD patients also showed decreased DC in the somatosensory and motor cortices and cerebellum (p < 0.05, AlphaSim-corrected). Compared with EOD patients, LOD patients showed increased centrality in the superior and middle temporal gyrus and decreased centrality in the occipital region (p < 0.05, AlphaSim-corrected). No significant correlation was found between the DC value and the symptom severity or disease duration in the patients after the correction for multiple comparisons. Conclusions:These findings indicate that the intrinsic abnormality of network centrality exists in a wide range of brain areas in LLD patients. LOD patients differ with EOD patients in cortical network centrality. Our study might help to strengthen the understanding of the pathophysiology of LLD and the potential neural substrates underlie related emotional and cognitive impairments observed in the patients
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