title
string | abstract
string | url
string | arxiv_id
string | date
string | category
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24-hour measurement of squeezed light using automated stable fiber system
|
In order to provide a cloud service of optical quantum computing, it is inevitable to stabilize the optical system for many hours. It is advantageous to construct a fiber-based system, which does not require spatial alignment. However, fiber-based systems are instead subject to fiber-specific instabilities. For instance, there are phase drifts due to ambient temperature changes and external disturbances, and polarization fluctuations due to the finite polarization extinction ratio of fiber components. Here, we report the success of measuring squeezed light with a fiber system for 24 hours. To do this, we introduce stabilization mechanics to suppress fluctuations in the fiber system, and integrated controller to automatically align the entire system. The squeezed light at the wavelength of 1545.3 nm is measured every 2 minutes, where automated alignments are inserted every 30 minutes. The squeezing levels with the average of -4.42 dB are recorded with an extremely small standard deviation of 0.08 dB over 24 hours.
|
https://arxiv.org/abs/2401.17533v1
|
2401.17533
|
2024-01-31
|
computer-graphics
|
24-Hour Relativistic Bit Commitment
|
Bit commitment is a fundamental cryptographic primitive in which a party
wishes to commit a secret bit to another party. Perfect security between
mistrustful parties is unfortunately impossible to achieve through the
asynchronous exchange of classical and quantum messages. Perfect security can
nonetheless be achieved if each party splits into two agents exchanging
classical information at times and locations satisfying strict relativistic
constraints. A relativistic multi-round protocol to achieve this was previously
proposed and used to implement a 2~millisecond commitment time. Much longer
durations were initially thought to be insecure, but recent theoretical
progress showed that this is not so. In this letter, we report on the
implementation of a 24-hour bit commitment based on timed high-speed optical
communication and fast data processing only, with all agents located within the
city of Geneva. This duration is more than six orders of magnitude longer than
before, and we argue that it could be extended to one year and allow much more
flexibility on the locations of the agents. Our implementation offers a
practical and viable solution for use in applications such as digital
signatures, secure voting and honesty-preserving auctions.
|
http://arxiv.org/abs/1605.07442v1
|
1605.07442
|
2016-05-24
|
computer-graphics
|
$^{24}$Mg($p$, $\alpha$)$^{21}$Na reaction study for spectroscopy of $^{21}$Na
|
The $^{24}$Mg($p$, $\alpha$)$^{21}$Na reaction was measured at the Holifield
Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to
better constrain spins and parities of energy levels in $^{21}$Na for the
astrophysically important $^{17}$F($\alpha, p$)$^{20}$Ne reaction rate
calculation. 31 MeV proton beams from the 25-MV tandem accelerator and enriched
$^{24}$Mg solid targets were used. Recoiling $^{4}$He particles from the
$^{24}$Mg($p$, $\alpha$)$^{21}$Na reaction were detected by a highly segmented
silicon detector array which measured the yields of $^{4}$He particles over a
range of angles simultaneously. A new level at 6661 $\pm$ 5 keV was observed in
the present work. The extracted angular distributions for the first four levels
of $^{21}$Na and Distorted Wave Born Approximation (DWBA) calculations were
compared to verify and extract angular momentum transfer.
|
http://arxiv.org/abs/1508.02128v1
|
1508.02128
|
2015-08-10
|
computer-graphics
|
24 rational curves on K3 surfaces
|
Given d in IN, we prove that all smooth K3 surfaces (over any field of characteristic p other than 2,3) of degree greater than 84d^2 contain at most 24 rational curves of degree at most d. In the exceptional characteristics, the same bounds hold for non-unirational K3 surfaces, and we develop analogous results in the unirational case. For d at least 3, we also construct K3 surfaces of any degree greater than 4d(d+1) with 24 rational curves of degree exactly d, thus attaining the above bounds.
|
https://arxiv.org/abs/1907.04182v3
|
1907.04182
|
2019-07-09
|
computer-graphics
|
24 synoptic maps of average magnetic field in 296 prominences measured by the Hanle effect during the ascending phase of solar cycle 21
|
Aims : We present 24 synoptic maps of solar filaments, in which the average unambiguous magnetic field vectors of 296 prominences were determined with Pic-du-Midi observations between 1974 and 1982. This was the ascending phase of cycle 21. Methods : The magnetic field was determined by interpreting the Hanle effect, which is observed in the \ion{He}{i} D$_3$ line. Previous results for the prominence field polarity and prominence chirality were applied to solve the fundamental ambiguity. The measurements were averaged in each prominence for accuracy reasons. Results : The result is twofold. First, alternating field directions can be observed from one neutral line to the next. Second, a general field alignment is found along a solar north-south field that is distorted by the differential rotation effect. The numerical data for the prominences and their magnetic field coordinates are provided as online material associated with this paper.
|
https://arxiv.org/abs/2007.08219v4
|
2007.08219
|
2020-07-16
|
computer-graphics
|
2.4-THz Bandwidth Optical Coherent Receiver Based on a Photonic Crystal Microcomb
|
We demonstrate a spectrally-sliced single-polarization optical coherent receiver with a record 2.4-THz bandwidth, using a 200-GHz tantalum pentoxide photonic crystal microring resonator as the local oscillator frequency comb.
|
https://arxiv.org/abs/2407.04060v1
|
2407.04060
|
2024-07-04
|
computer-graphics
|
25,000 optical fiber positioning robots for next-generation cosmology
|
Massively parallel multi-object spectrographs are on the leading edge of cosmology instrumentation. The highly successful Dark Energy Spectroscopic Instrument (DESI) which begun survey operations in May 2021, for example, has 5,000 robotically-actuated multimode fibers, which deliver light from thousands of individual galaxies and quasars simultaneously to an array of high-resolution spectrographs off-telescope. The redshifts are individually measured, thus providing 3D maps of the Universe in unprecedented detail, and enabling precise measurement of dark energy expansion and other key cosmological parameters. Here we present new work in the design and prototyping of the next generation of fiber-positioning robots. At 6.2 mm center-to-center pitch, with 1-2 um positioning precision, and in a scalable form factor, these devices will enable the next generation of cosmology instruments, scaling up to instruments with 10,000 to 25,000 fiber robots.
|
https://arxiv.org/abs/2212.07908v1
|
2212.07908
|
2022-12-15
|
computer-graphics
|
2500 vibronic eigenstates of the NO$_3$ radical
|
The nitrate radical NO$_3$ plays an important role in atmospheric chemistry, yet many aspects of its coupled and anharmonic vibronic structure remain elusive. Here, using an accurate, coupled full-dimensional diabatic potential that includes five electronic states, we revisit the vibronic spectrum associated with the electronic $\tilde X ^2A_2'$ state. Using recently developed tensor network state methods, we are able to compute more than 2500 vibronic states, thereby increasing the number of computed full-dimensional states by a factor of 50, compared to previous work. While we obtain good agreement with experiment for most of the assigned vibronic levels, for several others, we observe striking disagreement. Further, for the antisymmetric bending motion we find remarkably large symmetry-induced level splittings that are larger than the zero-order reference. We discuss non-negligible nonadiabatic effects and show that the Born-Oppenheimer approximation leads to significant errors in the spectrum.
|
https://arxiv.org/abs/2407.03398v2
|
2407.03398
|
2024-07-03
|
computer-graphics
|
(2.5+1)D Spatio-Temporal Scene Graphs for Video Question Answering
|
Spatio-temporal scene-graph approaches to video-based reasoning tasks, such as video question-answering (QA), typically construct such graphs for every video frame. These approaches often ignore the fact that videos are essentially sequences of 2D "views" of events happening in a 3D space, and that the semantics of the 3D scene can thus be carried over from frame to frame. Leveraging this insight, we propose a (2.5+1)D scene graph representation to better capture the spatio-temporal information flows inside the videos. Specifically, we first create a 2.5D (pseudo-3D) scene graph by transforming every 2D frame to have an inferred 3D structure using an off-the-shelf 2D-to-3D transformation module, following which we register the video frames into a shared (2.5+1)D spatio-temporal space and ground each 2D scene graph within it. Such a (2.5+1)D graph is then segregated into a static sub-graph and a dynamic sub-graph, corresponding to whether the objects within them usually move in the world. The nodes in the dynamic graph are enriched with motion features capturing their interactions with other graph nodes. Next, for the video QA task, we present a novel transformer-based reasoning pipeline that embeds the (2.5+1)D graph into a spatio-temporal hierarchical latent space, where the sub-graphs and their interactions are captured at varied granularity. To demonstrate the effectiveness of our approach, we present experiments on the NExT-QA and AVSD-QA datasets. Our results show that our proposed (2.5+1)D representation leads to faster training and inference, while our hierarchical model showcases superior performance on the video QA task versus the state of the art.
|
https://arxiv.org/abs/2202.09277v2
|
2202.09277
|
2022-02-18
|
computer-graphics
|
2.5-Connectivity: Unique Components, Critical Graphs, and Applications
|
If a biconnected graph stays connected after the removal of an arbitrary
vertex and an arbitrary edge, then it is called 2.5-connected. We prove that
every biconnected graph has a canonical decomposition into 2.5-connected
components. These components are arranged in a tree-structure. We also discuss
the connection between 2.5-connected components and triconnected components and
use this to present a linear-time algorithm which computes the 2.5-connected
components of a graph. We show that every critical 2.5-connected graph other
than K4 can be obtained from critical 2.5-connected graphs of smaller order
using simple graph operations. Furthermore, we demonstrate applications of
2.5-connected components in the context of cycle decompositions and cycle
packings.
|
http://arxiv.org/abs/2003.01498v2
|
2003.01498
|
2020-07-14
|
computer-graphics
|
2.5D Deep Learning for CT Image Reconstruction using a Multi-GPU implementation
|
While Model Based Iterative Reconstruction (MBIR) of CT scans has been shown
to have better image quality than Filtered Back Projection (FBP), its use has
been limited by its high computational cost. More recently, deep convolutional
neural networks (CNN) have shown great promise in both denoising and
reconstruction applications. In this research, we propose a fast reconstruction
algorithm, which we call Deep Learning MBIR (DL-MBIR), for approximating MBIR
using a deep residual neural network. The DL-MBIR method is trained to produce
reconstructions that approximate true MBIR images using a 16 layer residual
convolutional neural network implemented on multiple GPUs using Google
Tensorflow. In addition, we propose 2D, 2.5D and 3D variations on the DL-MBIR
method and show that the 2.5D method achieves similar quality to the fully 3D
method, but with reduced computational cost.
|
http://arxiv.org/abs/1812.08367v1
|
1812.08367
|
2018-12-20
|
computer-graphics
|
2.5D Image based Robotic Grasping
|
We consider the problem of robotic grasping using depth + RGB information
sampling from a real sensor. we design an encoder-decoder neural network to
predict grasp policy in real time. This method can fuse the advantage of depth
image and RGB image at the same time and is robust for grasp and observation
height.We evaluate our method in a physical robotic system and propose an
open-loop algorithm to realize robotic grasp operation. We analyze the result
of experiment from multi-perspective and the result shows that our method is
competitive with the state-of-the-art in grasp performance, real-time and model
size. The video is available in https://youtu.be/Wxw_r5a8qV0
|
http://arxiv.org/abs/1905.13675v1
|
1905.13675
|
2019-05-31
|
computer-graphics
|
2.5D Mapping, Pathfinding and Path Following For Navigation Of A Differential Drive Robot In Uneven Terrain
|
Safe navigation in uneven terrains is an important problem in robotic research. In this paper we propose a 2.5D navigation system which consists of elevation map building, path planning and local path following with obstacle avoidance. For local path following we use Model Predictive Path Integral (MPPI) control method. We propose novel cost-functions for MPPI in order to adapt it to elevation maps and motion through unevenness. We evaluate our system on multiple synthetic tests and in a simulated environment with different types of obstacles and rough surfaces.
|
https://arxiv.org/abs/2209.07252v1
|
2209.07252
|
2022-09-15
|
computer-graphics
|
2.5-D MHD Simulation of the Formation and Evolution of Plasmoids in Coronal Current Sheets
|
In the present paper, using MPI-AMRVAC, we perform a 2.5-D numerical MHD simulation of the dynamics and associated thermodynamical evolution of an initially force-free Harris current sheet subjected to an external velocity perturbation under the condition of uniform resistivity. The amplitude of the magnetic field is taken to be 10 Gauss, typical of the solar corona. We impose a Gaussian velocity pulse across this current sheet mimicking the interaction of fast magnetoacoustic waves with a current sheet in corona. This leads to a variety of dynamics and plasma processes in the current sheet, which is initially quasi-static. The initial pulse interacts with the current sheet and splits into a pair of counter-propagating wavefronts, which forms a rarefied region and leads to inflow and a thinning of the current sheet. The thinning results in Petschek-type magnetic reconnection followed by tearing instability and plasmoid formation. The reconnection outflows containing outward-moving plasmoids have accelerated motions with velocities ranging from 105-303 km/s. The average temperature and density of the plasmoids are found to be 8 MK and twice the background density of the solar corona, respectively. These estimates of velocity, temperature and density of plasmoids are similar to values reported from various solar coronal observations. Therefore, we infer that the external triggering of a quasi-static current sheet by a single velocity pulse is capable of initiating magnetic reconnection and plasmoid formation in the absence of a localized enhancement of resistivity in the solar corona.
|
https://arxiv.org/abs/2401.07048v1
|
2401.07048
|
2024-01-13
|
computer-graphics
|
2.5D Multi-view Averaging Diffusion Model for 3D Medical Image Translation: Application to Low-count PET Reconstruction with CT-less Attenuation Correction
|
Positron Emission Tomography (PET) is an important clinical imaging tool but inevitably introduces radiation hazards to patients and healthcare providers. Reducing the tracer injection dose and eliminating the CT acquisition for attenuation correction can reduce the overall radiation dose, but often results in PET with high noise and bias. Thus, it is desirable to develop 3D methods to translate the non-attenuation-corrected low-dose PET (NAC-LDPET) into attenuation-corrected standard-dose PET (AC-SDPET). Recently, diffusion models have emerged as a new state-of-the-art deep learning method for image-to-image translation, better than traditional CNN-based methods. However, due to the high computation cost and memory burden, it is largely limited to 2D applications. To address these challenges, we developed a novel 2.5D Multi-view Averaging Diffusion Model (MADM) for 3D image-to-image translation with application on NAC-LDPET to AC-SDPET translation. Specifically, MADM employs separate diffusion models for axial, coronal, and sagittal views, whose outputs are averaged in each sampling step to ensure the 3D generation quality from multiple views. To accelerate the 3D sampling process, we also proposed a strategy to use the CNN-based 3D generation as a prior for the diffusion model. Our experimental results on human patient studies suggested that MADM can generate high-quality 3D translation images, outperforming previous CNN-based and Diffusion-based baseline methods.
|
https://arxiv.org/abs/2406.08374v2
|
2406.08374
|
2024-06-12
|
computer-graphics
|
2.5D Root of Trust: Secure System-Level Integration of Untrusted Chiplets
|
Dedicated, after acceptance and publication, in memory of the late Vassos
Soteriou. For the first time, we leverage the 2.5D interposer technology to
establish system-level security in the face of hardware- and software-centric
adversaries. More specifically, we integrate chiplets (i.e., third-party hard
intellectual property of complex functionality, like microprocessors) using a
security-enforcing interposer. Such hardware organization provides a robust
2.5D root of trust for trustworthy, yet powerful and flexible, computation
systems. The security paradigms for our scheme, employed firmly by design and
construction, are: 1) stringent physical separation of trusted from untrusted
components, and 2) runtime monitoring. The system-level activities of all
untrusted commodity chiplets are checked continuously against security policies
via physically separated security features. Aside from the security promises,
the good economics of outsourced supply chains are still maintained; the system
vendor is free to procure chiplets from the open market, while only producing
the interposer and assembling the 2.5D system oneself. We showcase our scheme
using the Cortex-M0 core and the AHB-Lite bus by ARM, building a secure 64-core
system with shared memories. We evaluate our scheme through hardware
simulation, considering different threat scenarios. Finally, we devise a
physical-design flow for 2.5D systems, based on commercial-grade design tools,
to demonstrate and evaluate our 2.5D root of trust.
|
http://arxiv.org/abs/2009.02412v2
|
2009.02412
|
2020-09-29
|
computer-graphics
|
2.5D Super-Resolution Approaches for X-ray Computed Tomography-based Inspection of Additively Manufactured Parts
|
X-ray computed tomography (XCT) is a key tool in non-destructive evaluation of additively manufactured (AM) parts, allowing for internal inspection and defect detection. Despite its widespread use, obtaining high-resolution CT scans can be extremely time consuming. This issue can be mitigated by performing scans at lower resolutions; however, reducing the resolution compromises spatial detail, limiting the accuracy of defect detection. Super-resolution algorithms offer a promising solution for overcoming resolution limitations in XCT reconstructions of AM parts, enabling more accurate detection of defects. While 2D super-resolution methods have demonstrated state-of-the-art performance on natural images, they tend to under-perform when directly applied to XCT slices. On the other hand, 3D super-resolution methods are computationally expensive, making them infeasible for large-scale applications. To address these challenges, we propose a 2.5D super-resolution approach tailored for XCT of AM parts. Our method enhances the resolution of individual slices by leveraging multi-slice information from neighboring 2D slices without the significant computational overhead of full 3D methods. Specifically, we use neighboring low-resolution slices to super-resolve the center slice, exploiting inter-slice spatial context while maintaining computational efficiency. This approach bridges the gap between 2D and 3D methods, offering a practical solution for high-throughput defect detection in AM parts.
|
https://arxiv.org/abs/2412.04525v1
|
2412.04525
|
2024-12-05
|
computer-graphics
|
2.5D Thermometry Maps for MRI-guided Tumor Ablation
|
Fast and reliable monitoring of volumetric heat distribution during MRI-guided tumor ablation is an urgent clinical need. In this work, we introduce a method for generating 2.5D thermometry maps from uniformly distributed 2D MRI phase images rotated around the applicator's main axis. The images can be fetched directly from the MR device, reducing the delay between image acquisition and visualization. For reconstruction, we use a weighted interpolation on a cylindric coordinate representation to calculate the heat value of voxels in a region of interest. A pilot study on 13 ex vivo bio protein phantoms with flexible tubes to simulate a heat sink effect was conducted to evaluate our method. After thermal ablation, we compared the measured coagulation zone extracted from the post-treatment MR data set with the output of the 2.5D thermometry map. The results show a mean Dice score of 0.75+-0.07, a sensitivity of 0.77+-0.03, and a reconstruction time within 18.02ms+-5.91ms. Future steps should address improving temporal resolution and accuracy, e.g., incorporating advanced bioheat transfer simulations.
|
https://arxiv.org/abs/2108.05734v1
|
2108.05734
|
2021-08-12
|
computer-graphics
|
2.5D turbulence in shear-thinning jets
|
The dimensional transition in turbulent jets of a shear-thinning fluid is studied via direct numerical simulations. Our findings reveal that under vertical confinement, the flow exhibits a unique mixed-dimensional (or 2.5D) state, where large-scale two-dimensional and small-scale three-dimensional structures coexist. This transition from three-dimensional turbulence near the inlet to two-dimensional dynamics downstream is dictated by the level of confinement: weak confinement guarantees turbulence to remain three-dimensional, whereas strong confinement forces the transition to two-dimensions; the mixed-dimensional state is observed for moderate confinement and it emerges as soon as flow scales are larger than the vertical length. In this scenario, we observed that the mixed-dimensional state is an overall more energetic state and it shows a multi-cascade process, where the direct cascade of energy at small scales and the direct cascade of enstrophy at large scales coexist. The results provide insights into the complex dynamics of confined turbulent flows, relevant in both natural and industrial settings.
|
https://arxiv.org/abs/2407.01038v4
|
2407.01038
|
2024-07-01
|
computer-graphics
|
2.5D U-Net with Depth Reduction for 3D CryoET Object Identification
|
Cryo-electron tomography (cryoET) is a crucial technique for unveiling the structure of protein complexes. Automatically analyzing tomograms captured by cryoET is an essential step toward understanding cellular structures. In this paper, we introduce the 4th place solution from the CZII - CryoET Object Identification competition, which was organized to advance the development of automated tomogram analysis techniques. Our solution adopted a heatmap-based keypoint detection approach, utilizing an ensemble of two different types of 2.5D U-Net models with depth reduction. Despite its highly unified and simple architecture, our method achieved 4th place, demonstrating its effectiveness.
|
https://arxiv.org/abs/2502.13484v1
|
2502.13484
|
2025-02-19
|
computer-graphics
|
2.5D Vehicle Odometry Estimation
|
It is well understood that in ADAS applications, a good estimate of the pose of the vehicle is required. This paper proposes a metaphorically named 2.5D odometry, whereby the planar odometry derived from the yaw rate sensor and four wheel speed sensors is augmented by a linear model of suspension. While the core of the planar odometry is a yaw rate model that is already understood in the literature, we augment this by fitting a quadratic to the incoming signals, enabling interpolation, extrapolation, and a finer integration of the vehicle position. We show, by experimental results with a DGPS/IMU reference, that this model provides highly accurate odometry estimates, compared with existing methods. Utilising sensors that return the change in height of vehicle reference points with changing suspension configurations, we define a planar model of the vehicle suspension, thus augmenting the odometry model. We present an experimental framework and evaluations criteria by which the goodness of the odometry is evaluated and compared with existing methods. This odometry model has been designed to support low-speed surround-view camera systems that are well-known. Thus, we present some application results that show a performance boost for viewing and computer vision applications using the proposed odometry
|
https://arxiv.org/abs/2111.08398v1
|
2111.08398
|
2021-11-16
|
computer-graphics
|
2.5D Visual Relationship Detection
|
Visual 2.5D perception involves understanding the semantics and geometry of a scene through reasoning about object relationships with respect to the viewer in an environment. However, existing works in visual recognition primarily focus on the semantics. To bridge this gap, we study 2.5D visual relationship detection (2.5VRD), in which the goal is to jointly detect objects and predict their relative depth and occlusion relationships. Unlike general VRD, 2.5VRD is egocentric, using the camera's viewpoint as a common reference for all 2.5D relationships. Unlike depth estimation, 2.5VRD is object-centric and not only focuses on depth. To enable progress on this task, we create a new dataset consisting of 220k human-annotated 2.5D relationships among 512K objects from 11K images. We analyze this dataset and conduct extensive experiments including benchmarking multiple state-of-the-art VRD models on this task. Our results show that existing models largely rely on semantic cues and simple heuristics to solve 2.5VRD, motivating further research on models for 2.5D perception. The new dataset is available at https://github.com/google-research-datasets/2.5vrd.
|
https://arxiv.org/abs/2104.12727v1
|
2104.12727
|
2021-04-26
|
computer-graphics
|
2.5D Visual Sound
|
Binaural audio provides a listener with 3D sound sensation, allowing a rich
perceptual experience of the scene. However, binaural recordings are scarcely
available and require nontrivial expertise and equipment to obtain. We propose
to convert common monaural audio into binaural audio by leveraging video. The
key idea is that visual frames reveal significant spatial cues that, while
explicitly lacking in the accompanying single-channel audio, are strongly
linked to it. Our multi-modal approach recovers this link from unlabeled video.
We devise a deep convolutional neural network that learns to decode the
monaural (single-channel) soundtrack into its binaural counterpart by injecting
visual information about object and scene configurations. We call the resulting
output 2.5D visual sound---the visual stream helps "lift" the flat single
channel audio into spatialized sound. In addition to sound generation, we show
the self-supervised representation learned by our network benefits audio-visual
source separation. Our video results:
http://vision.cs.utexas.edu/projects/2.5D_visual_sound/
|
http://arxiv.org/abs/1812.04204v4
|
1812.04204
|
2018-12-11
|
computer-graphics
|
25-Fold Resolution Enhancement of X-ray Microscopy Using Multipixel Ghost Imaging
|
Hard x-ray imaging is indispensable across diverse fields owing to its high penetrability. However, the resolution of traditional x-ray imaging modalities, such as computed tomography (CT) systems, is constrained by factors including beam properties, the absence of optical components, and detection resolution. As a result, typical resolution in commercial imaging systems is limited to a few hundred microns. This study advances high-photon-energy imaging by extending the concept of computational ghost imaging to multipixel ghost imaging with x-rays. We demonstrate a remarkable enhancement in resolution from 500 microns to approximately 20 microns for an image spanning 0.9 by 1 cm^2, comprised of 400,000 pixels and involving only 1000 realizations. Furthermore, we present a high-resolution CT reconstruction using our method, revealing enhanced visibility and resolution. Our achievement is facilitated by an innovative x-ray lithography technique and the computed tiling of images captured by each detector pixel. Importantly, this method can be scaled up for larger images without sacrificing the short measurement time, thereby opening intriguing possibilities for noninvasive high-resolution imaging of small features that are invisible with the present modalities.
|
https://arxiv.org/abs/2402.14023v1
|
2402.14023
|
2024-02-07
|
computer-graphics
|
25 MeV Solar Proton Events in Cycle 24 and Previous Cycles
|
We summarize observations of around a thousand solar energetic particle (SEP)
events since 1967 that include ~25 MeV protons, made by various near-Earth
spacecraft (IMPs 4, 5, 7, 8, ISEE 3, SOHO), that encompass Solar Cycle 20 to
the current cycle (24). We also discuss recent observations of similar SEP
events in Cycle 24 made by the STEREO spacecraft. The observations show, for
example, that the time distribution of ~25 MeV proton events varies from cycle
to cycle. In particular, the time evolution of the SEP occurrence rate in Cycle
24 is strongly asymmetric between the northern and southern solar hemispheres,
and tracks the sunspot number in each hemisphere, whereas Cycle 23 was more
symmetric. There was also an absence of 25 MeV proton events during the solar
minimum preceding Cycle 24 (other minima show occasional, often reasonably
intense events). So far, events comparable to the exceptionally intense events
detected in Cycles 22 and 23 have not been observed at Earth in Cycle 24,
though Cycle 21 (the largest of the cycles considered here) also apparently
lacked such events. We note a correlation between the rates of intense 25 MeV
proton events and "ground level enhancements" (GLEs) observed by neutron
monitors, since 1967, and conclude that the number of "official" GLEs observed
to date in Cycle 24 appears to be significantly lower than expected (5 to
7+/-1) based on the rate of intense 25 MeV proton events in this cycle.
|
http://arxiv.org/abs/1604.07873v2
|
1604.07873
|
2016-07-29
|
computer-graphics
|
2.5-MHD models of circumstellar discs around FS~CMa post-mergers : II. Stationary accretion stage
|
We study the star-disc interaction in the presence of the strong magnetic field ($B_\star=6.2kG$) of a slowly rotating star. This situation describes a post-merger of the spectral type B and has not been previously investigated. We perform a set of resistive and viscosity $2.5D$-magnetohydrodynamical simulations using the PLUTO code. Based on our previous work, we consider the initial gas disc density $\rho_{d0}=10^{-13}\mathrm{gcm}^{-3}$ since it describes the conditions around IRAS 17449+2320 well. We find that the fall of gas towards the star occurs in the mid-plane, and remarkably, intermittent backflow takes place in the mid-plane in all of our models for $R\geq10R_\star$. However, we do not rule out that the funnel effect may occur and cause the accretion closer to the poles. Also, when larger values of viscosity ($\alpha_\nu=1$) and stellar rotation rate ($\delta_\star=0.2$) are considered, we find that the disc exhibits a thickening which is characteristic of FS~CMa-type stellar objects. Additionally, we find that the poloidal magnetic field lines twist over short periods of time, leading to magnetic reconnection causing coronal heating that could explain the presence of the Raman lines found observationally in several FS~CMa stars. Lastly, we find the formation of several knots in the magnetic field lines near and in the mid-plane of the disc which produce perturbations in the density and velocity components, as well as the formation of shallow gaps whose position depends on the inflation of the magnetic field lines.
|
https://arxiv.org/abs/2402.00720v2
|
2402.00720
|
2024-02-01
|
computer-graphics
|
2.5-MHD models of circumstellar discs around FS~CMa post-mergers : I. Non-stationary accretion stage
|
We investigate the dynamic evolution of gaseous region around FS~CMa post-mergers. Due to the slow rotation of a central B-type star, the dynamics is driven mainly by the magnetic field of the central star. Recent observations have allowed us to set a realistic initial conditions such as, the magnetic field value ($B_\star\approx6\times10^{3}G$), the mass of the central star ($M_\star=6M_\odot$), and the initial disc density $\rho_{d0}\in[10^{-13}\mathrm{g\,cm^{-3}},10^{-11}\mathrm{g \, cm^{-3}}] $. We use the PLUTO code to perform 2.5D-MHD simulations of thin and thick discs models. Especially relevant for the interpretation of the observed properties of FS~CMa post-mergers are the results for low-density discs, in which we find formation of a jet emerging from inner edge of the disc, as well as the formation of the so called "hot plasmoid" in the corona region. Jets are probably detected as discrete absorption components in the resonance lines of FS~CMa stars. Moreover, the magnetic field configuration in the low-density plasma region, favors the appearance of magnetocentrifugal winds from the disc. The currents toward the star created by the magnetic field may explain accidentally observed material infall. The disc structure is significantly changed due to the presence of the magnetic field. The magnetic field is also responsible for the formation of a hot corona as observed in several FS~CMa stars through the Raman lines. Our results are valid for all magnetic stars surrounded by a low density plasma, i.e., some of stars showing the B[e] phenomenon.
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https://arxiv.org/abs/2306.16073v1
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2306.16073
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2023-06-28
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computer-graphics
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25 open questions about vector bundles and their moduli
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We present 25 open questions about moduli spaces of vector bundles and related topics and discuss some longstanding conjectures. We hope to inspire young researchers to engage in this area of research.
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https://arxiv.org/abs/2106.06434v1
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2106.06434
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2021-06-11
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computer-graphics
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2.5PN accurate waveform information for generic-planar-orbit binaries in effective one-body models
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We provide the post-Newtonian (PN) waveform for binary systems in motion along generic planar orbits at 2.5PN accuracy, in terms of the dynamical variables of the effective one-body (EOB) formalism. In addition to the calculation of the higher order terms for all the contributions to the waveform that have been already considered in previous avatars of EOB models, we also compute the EOB expression of the oscillatory memory terms. These are purely non-circular contributions, first appearing at 1.5PN order, that have been so far neglected in the EOB literature. This should foster their inclusion in EOB models and the definitive assessment of their role in shaping gravitational wave signals at infinity. To further promote the application of our results, we also derive associated non-circular factors according to the waveform factorization prescription of the non-circular EOB model TEOBResumS-DALI; the result is a set of ready-to-use non-circular factors that can be directly implemented as extra non-circular corrections in the waveform of TEOBResumS-DALI.
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https://arxiv.org/abs/2305.14440v3
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2305.14440
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2023-05-23
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computer-graphics
|
$^{25}$Si $\beta^+$-decay spectroscopy
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$\beta$-decay spectroscopy provides valuable information on exotic nuclei and
a stringent test for nuclear theories beyond the stability line. To search for
new $\beta$-delayed protons and $\gamma$ rays of $^{25}$Si to investigate the
properties of $^{25}$Al excited states. $^{25}$Si $\beta$ decays were measured
by using the Gaseous Detector with Germanium Tagging system at the National
Superconducting Cyclotron Laboratory. The protons and $\gamma$ rays emitted in
the decay were detected simultaneously. A Monte Carlo method was used to model
the Doppler broadening of $^{24}$Mg $\gamma$-ray lines caused by nuclear recoil
from proton emission. Shell-model calculations using two newly-developed
\textit{sd}-shell Hamiltonians, USDC and USDI, were performed. The most precise
$^{25}$Si half-life to date has been determined. A new proton branch at
724(4)~keV and new proton-$\gamma$-ray coincidences have been identified. Three
$^{24}$Mg $\gamma$-ray lines and eight $^{25}$Al $\gamma$-ray lines are
observed for the first time in $^{25}$Si decay. The first measurement of the
$^{25}$Si $\beta$-delayed $\gamma$ ray intensities through the $^{25}$Al
unbound states is reported. All the bound states of $^{25}$Al are observed to
be populated in the $\beta$ decay of $^{25}$Si. Several inconsistencies between
the previous measurements have been resolved, and new information on the
$^{25}$Al level scheme is provided. An enhanced decay scheme has been
constructed and compared to the mirror decay of $^{25}$Na and the shell-model
calculations. The measured excitation energies, $\gamma$-ray and proton
branchings, log~$ft$ values, and Gamow-Teller transition strengths for the
states of $^{25}$Al populated in the $\beta$ decay of $^{25}$Si are in good
agreement with the shell model calculations, offering gratifyingly consistent
insights into the fine nuclear structure of $^{25}$Al.
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http://arxiv.org/abs/2009.00825v2
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2009.00825
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2020-09-13
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computer-graphics
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25 Tweets to Know You: A New Model to Predict Personality with Social Media
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Predicting personality is essential for social applications supporting
human-centered activities, yet prior modeling methods with users written text
require too much input data to be realistically used in the context of social
media. In this work, we aim to drastically reduce the data requirement for
personality modeling and develop a model that is applicable to most users on
Twitter. Our model integrates Word Embedding features with Gaussian Processes
regression. Based on the evaluation of over 1.3K users on Twitter, we find that
our model achieves comparable or better accuracy than state of the art
techniques with 8 times fewer data.
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http://arxiv.org/abs/1704.05513v1
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1704.05513
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2017-04-18
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computer-graphics
|
2.5 Years in Class: A Multimodal Textbook for Vision-Language Pretraining
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Compared to image-text pair data, interleaved corpora enable Vision-Language Models (VLMs) to understand the world more naturally like humans. However, such existing datasets are crawled from webpage, facing challenges like low knowledge density, loose image-text relations, and poor logical coherence between images. On the other hand, the internet hosts vast instructional videos (e.g., online geometry courses) that are widely used by humans to learn foundational subjects, yet these valuable resources remain underexplored in VLM training. In this paper, we introduce a high-quality \textbf{multimodal textbook} corpus with richer foundational knowledge for VLM pretraining. It collects over 2.5 years of instructional videos, totaling 22,000 class hours. We first use an LLM-proposed taxonomy to systematically gather instructional videos. Then we progressively extract and refine visual (keyframes), audio (ASR), and textual knowledge (OCR) from the videos, and organize as an image-text interleaved corpus based on temporal order. Compared to its counterparts, our video-centric textbook offers more coherent context, richer knowledge, and better image-text alignment. Experiments demonstrate its superb pretraining performance, particularly in knowledge- and reasoning-intensive tasks like ScienceQA and MathVista. Moreover, VLMs pre-trained on our textbook exhibit outstanding interleaved context awareness, leveraging visual and textual cues in their few-shot context for task solving. Our code are available at https://github.com/DAMO-NLP-SG/multimodal_textbook.
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https://arxiv.org/abs/2501.00958v4
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2501.00958
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2025-01-01
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computer-graphics
|
25 years of CNNs: Can we compare to human abstraction capabilities?
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We try to determine the progress made by convolutional neural networks over
the past 25 years in classifying images into abstractc lasses. For this purpose
we compare the performance of LeNet to that of GoogLeNet at classifying
randomly generated images which are differentiated by an abstract property
(e.g., one class contains two objects of the same size, the other class two
objects of different sizes). Our results show that there is still work to do in
order to solve vision problems humans are able to solve without much
difficulty.
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http://arxiv.org/abs/1607.08366v1
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1607.08366
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2016-07-28
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computer-graphics
|
25 years of criticality in neuroscience -- established results, open controversies, novel concepts
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Twenty-five years ago, Dunkelmann and Radons (1994) proposed that neural
networks should self-organize to a critical state. In models, criticality
offers a number of computational advantages. Thus this hypothesis, and in
particular the experimental work by Beggs and Plenz (2003), has triggered an
avalanche of research, with thousands of studies referring to it. Nonetheless,
experimental results are still contradictory. How is it possible, that a
hypothesis has attracted active research for decades, but nonetheless remains
controversial? We discuss the experimental and conceptual controversy, and then
present a parsimonious solution that (i) unifies the contradictory experimental
results, (ii) avoids disadvantages of a critical state, and (iii) enables
rapid, adaptive tuning of network properties to task requirements.
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http://arxiv.org/abs/1903.05129v1
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1903.05129
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2019-03-12
|
computer-graphics
|
25 Years of Self-Organized Criticality: Concepts and Controversies
|
Introduced by the late Per Bak and his colleagues, self-organized criticality
(SOC) has been one of the most stimulating concepts to come out of statistical
mechanics and condensed matter theory in the last few decades, and has played a
significant role in the development of complexity science. SOC, and more
generally fractals and power laws, have attacted much comment, ranging from the
very positive to the polemical. The other papers in this special issue
(Aschwanden et al, 2014; McAteer et al, 2014; Sharma et al, 2015) showcase the
considerable body of observations in solar, magnetospheric and fusion plasma
inspired by the SOC idea, and expose the fertile role the new paradigm has
played in approaches to modeling and understanding multiscale plasma
instabilities. This very broad impact, and the necessary process of adapting a
scientific hypothesis to the conditions of a given physical system, has meant
that SOC as studied in these fields has sometimes differed significantly from
the definition originally given by its creators. In Bak's own field of
theoretical physics there are significant observational and theoretical open
questions, even 25 years on (Pruessner, 2012). One aim of the present review is
to address the dichotomy between the great reception SOC has received in some
areas, and its shortcomings, as they became manifest in the controversies it
triggered. Our article tries to clear up what we think are misunderstandings of
SOC in fields more remote from its origins in statistical mechanics, condensed
matter and dynamical systems by revisiting Bak, Tang and Wiesenfeld's original
papers.
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http://arxiv.org/abs/1504.04991v1
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1504.04991
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2015-04-20
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computer-graphics
|
25 Years of Self-Organized Criticality: Numerical Detection Methods
|
The detection and characterization of self-organized criticality (SOC), in
both real and simulated data, has undergone many significant revisions over the
past 25 years. The explosive advances in the many numerical methods available
for detecting, discriminating, and ultimately testing, SOC have played a
critical role in developing our understanding of how systems experience and
exhibit SOC. In this article, methods of detecting SOC are reviewed; from
correlations to complexity to critical quantities. A description of the basic
autocorrelation method leads into a detailed analysis of application-oriented
methods developed in the last 25 years. In the second half of this manuscript
space-based, time-based and spatial-temporal methods are reviewed and the
prevalence of power laws in nature is described, with an emphasis on event
detection and characterization. The search for numerical methods to clearly and
unambiguously detect SOC in data often leads us outside the comfort zone of our
own disciplines - the answers to these questions are often obtained by studying
the advances made in other fields of study. In addition, numerical detection
methods often provide the optimum link between simulations and experiments in
scientific research. We seek to explore this boundary where the rubber meets
the road, to review this expanding field of research of numerical detection of
SOC systems over the past 25 years, and to iterate forwards so as to provide
some foresight and guidance into developing breakthroughs in this subject over
the next quarter of a century.
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http://arxiv.org/abs/1506.08142v1
|
1506.08142
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2015-06-26
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computer-graphics
|
25 Years of Signal Processing Advances for Multiantenna Communications
|
Wireless communication technology has progressed dramatically over the past 25 years, in terms of societal adoption as well as technical sophistication. In 1998, mobile phones were still in the process of becoming compact and affordable devices that could be widely utilized in both developed and developing countries. There were "only" 300 million mobile subscribers in the world [1]. Cellular networks were among the first privatized telecommunication markets, and competition turned the devices into fashion accessories with attractive designs that could be individualized. The service was circumscribed to telephony and text messaging, but it was groundbreaking in that, for the first time, telecommunication was between people rather than locations. Wireless networks have changed dramatically over the past few decades, enabling this revolution in service provisioning and making it possible to accommodate the ensuing dramatic growth in traffic. There are many contributing components, including new air interfaces for faster transmission, channel coding for enhanced reliability, improved source compression to remove redundancies, and leaner protocols to reduce overheads. Signal processing is at the core of these improvements, but nowhere has it played a bigger role than in the development of multiantenna communication. This article tells the story of how major signal processing advances have transformed the early multiantenna concepts into mainstream technology over the past 25 years. The story therefore begins somewhat arbitrarily in 1998. A broad account of the state-of-the-art signal processing techniques for wireless systems by 1998 can be found in [2], and its contrast with recent textbooks such as [3]-[5] reveals the dramatic leap forward that has taken place in the interim.
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https://arxiv.org/abs/2304.02677v1
|
2304.02677
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2023-04-05
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computer-graphics
|
25 years of XMM-Newton observations of the Sgr A complex: 3D distribution and internal structure of the clouds
|
Sgr A* is currently very faint. However, X-ray radiation reflected by the Sgr A complex, a group of nearby molecular clouds, suggests that it went through one or more periods of high activity some hundreds of years ago. We aim to determine whether previously proposed physical scenarios are consistent with the observed X-ray variability over the past 25 years, and to characterize the spatial distribution, shape, and internal structure of the clouds. We exploit the full set of XMM-Newton observations, extending the previously studied dataset on variability by at least 12 years. Starting from the recent IXPE result that places the so-called Bridge cloud 26 pc behind Sgr A*, we reconstruct the LOS position of the other clouds, assuming that they were illuminated by a single flare. Additionally, we derive the probability density function (PDF) of the molecular density. We also study the 3D geometry of the complex in case two flares illuminate the clouds. As of spring 2024, the lightfront is still illuminating the Sgr A complex, with the Bridge currently being the brightest cloud. The other clouds in the complex have faded significantly. In the single flare scenario, the Sgr A complex is located $\simeq$ 25 pc behind Sgr A*. In the past 25 years, the illuminated region spans 10-15 pc along the LOS. The derived PDF is roughly log-normal, consistent with previous Chandra results, with a possible high-density excess. Both a single and a multiple flares scenario can explain the observed X-ray variability. Previous concerns about the single flare scenario, raised by shorter monitoring, are now overcome in the 25 years of monitoring. If two flares illuminate the clouds, they must be separated by at least $\sim$ 30 years. We speculate that these clouds are closer to Sgr A* than the nuclear molecular ring at $\simeq$ 100-200 pc and possibly drifting from the ring to the inner region of the Galaxy.
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https://arxiv.org/abs/2501.09737v1
|
2501.09737
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2025-01-16
|
computer-graphics
|
26.5 ps Time Resolution Using 50 μm Low Gain Avalanche Detectors Fabricated by Micron Semiconductor Ltd
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Low Gain Avalanche Detectors (LGADs) are silicon semiconductor sensors with an implanted thin p-doped multiplication layer that is designed to provide low gain. Most importantly, LGADs are specifically engineered to provide excellent spatial and temporal resolution simultaneously. The technology shows promising prospects of fulfilling the 4D tracking requirements of future high energy physics experiments. Micron Semiconductor Ltd. has fabricated LGADs with an active thickness of 50 $\mu$m. The electrical and timing performance has been measured and compared with devices fabricated at IMB-CNM for reference. 50 $\mu$m thin LGADs by Micron Semiconductor Ltd. were measured to have a timing resolution in the region of 30 ps using a dedicated setup involving minimum ionising particles produced by Sr-90. Specifically, the best timing resolution of 26.5 ps was measured at a bias voltage of 200 V at -30{\deg}C.
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https://arxiv.org/abs/2310.06183v1
|
2310.06183
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2023-10-09
|
computer-graphics
|
$^{26}$Al gamma rays from the Galaxy with INTEGRAL/SPI
|
The presence of radioactive $^{26}$Al at 1.8 MeV reflects ongoing nucleosynthesis in the Milky Way. Diffuse emission from its decay can be measured with gamma-ray telescopes in space. The intensity, line shape, and spatial distribution of the $^{26}$Al emission allow a study of these nucleosynthesis sources. The line parameters trace massive-star feedback in the interstellar medium due to its 1~My lifetime. We aim to deepen previous studies of the $^{26}$Al emission in the Milky Way, using all gamma-ray data including single and double events as collected with SPI on INTEGRAL from 2003 until 2020. We apply improved spectral response and background as evaluated from tracing spectral details over the entire mission. The exposure for Galactic $^{26}$Al emission is enhanced using all event types measured within SPI. We re-determine the intensity of Galactic $^{26}$Al emission across the entire sky, through maximum likelihood fits of simulated and model-built sky distributions to SPI spectra for single and for double detector hits. We find an all-sky flux of (1.84$\pm$0.03$)\times$10$^{-3}$~ph~cm$^{-2}$s$^{-1}$ in the 1.809~MeV line from $^{26}$Al, determined as fitted to sky distributions from previous observations with COMPTEL. Significant emission from higher latitudes indicate an origin from nearby massive-star groups and superbubbles, also supported by a bottom-up population synthesis model. The line centroid is found at (1809.83$\pm$0.04~keV, and line broadening from source kinematics integrated over the sky is (0.62$\pm0.3$)~keV (FWHM).
|
https://arxiv.org/abs/2212.11228v1
|
2212.11228
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2022-12-21
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computer-graphics
|
26Al kinematics: superbubbles following the spiral arms? Constraints from the statistics of star clusters and HI supershells
|
High energy resolution spectroscopy of the 1.8 MeV radioactive decay line of
26Al with the SPI instrument on board the INTEGRAL satellite has recently
revealed that diffuse 26Al has large velocities in comparison to other
components of the interstellar medium in the Milky Way. 26Al shows Galactic
rotation in the same sense as the stars and other gas tracers, but reaches
excess velocities up to 300 km/s. We investigate if this result can be
understood in the context of superbubbles, taking into account the statistics
of young star clusters and H I supershells, as well as the association of young
star clusters with spiral arms. We derive energy output and 26Al mass of star
clusters as a function of the cluster mass via population synthesis from
stellar evolutionary tracks of massive stars. [...] We link this to the size
distribution of HI supershells and assess the properties of likely
26Al-carrying superbubbles. 26Al is produced by star clusters of all masses
above about 200 solar masses, roughly equally contributed over a logarithmic
star cluster mass scale, and strongly linked to the injection of feedback
energy. The observed superbubble size distribution cannot be related to the
star cluster mass function in a straight forward manner. In order to avoid that
the added volume of all superbubbles exceeds the volume of the Milky Way,
individual superbubbles have to merge frequently. If any two superbubbles
merge, or if 26Al is injected off-centre in a bigger HI supershell we expect
the hot 26Al-carrying gas to obtain velocities of the order of the typical
sound speed in superbubbles, about 300 km/s before decay. [...]
|
http://arxiv.org/abs/1504.03120v1
|
1504.03120
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2015-04-13
|
computer-graphics
|
2.6mJ/100Hz CEP stable near-single-cycle 4{\mu}m laser based on OPCPA and hollow-core-fiber compression
|
A carrier envelope phase stable near-single cycle mid-infrared laser based on
optical parametric chirped pulse amplification and hollow-core-fiber
compression is demonstrated. 4 {\mu}m laser pulses with 11.8 mJ energy are
delivered from a KTA based OPCPA with 100 Hz repetition rate, and compressed to
be ~105 fs by a two-grating compressor with efficiency over 50%. Subsequently,
the pulse spectrum is broadened by employing a krypton gas-filled
hollow-core-fiber (HCF). Then, the pulse duration is further compressed to 21.5
fs through a CaF2 bulk material with energy of 2.6 mJ and stability of 0.9%
RMS, which is about 1.6 cycle for 4 {\mu}m laser pulse. The near-single cycle 4
{\mu}m laser pulse CEP is passively stabilized with ~370 mrad based on a CEP
stable 4 {\mu}m OPA injection.
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http://arxiv.org/abs/1712.07327v1
|
1712.07327
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2017-12-20
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computer-graphics
|
$2.6 M_\odot$ Compact Object and Neutron Stars within Eddington-Inspired Born-Infeld Theory of Gravity
|
In the context of whether a massive compact object recently observed in the GW190814 event is a neutron star (NS) or not, we have studied the role of the parameters $\kappa$ and $\Lambda_c$ of the Eddington-inspired Born-Infeld (EiBI) gravity theory on the NS mass-radius relation, moment of inertia, and tidal deformability. The results are compared to recent observation constraints extracted from the analysis of NS observation data. The NS core equation of state (EoS) is calculated using the relativistic mean-field model with the G3 parameter set. In the hyperon sector, the SU(3) and hyperon potential depths are used to determine the hyperon coupling constants. For the inner and outer crusts, we use the crust EoS from Miyatsu et al. (2013). We also maintain the sound speed to not exceed $c$/$\sqrt{3}$ at high densities. We have found that, in general, the NS mass significantly depends on the value of $\kappa$, and the radius $R$ is sensitive to the value of $\Lambda_c$. Moreover, as $\Lambda_c$ is equal to zero or less than the accepted bound of the cosmological constant, the NS within the EiBI theory is compatible with observation constraints, including $2.0 M_\odot$ mass, canonical radius $R_{1.4 M_{\odot}}$, moment of inertia, and tidal deformation. Our investigation also reveals that the $2.6 M_\odot$ mass compact object and current observational constraint of canonical radius $R_{1.4 M_{\odot}}$ can simultaneously be satisfied only when the $\Lambda_c$ value is unphysically too large and negative. Therefore, within the spesific EoS employed in this work, we conclude that the secondary object with $2.6 M_\odot$ observed in the GW190814 event is not likely a static (or a slow-rotating) NS within the EiBI gravity theory.
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https://arxiv.org/abs/2109.05718v1
|
2109.05718
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2021-09-13
|
computer-graphics
|
26ms Inference Time for ResNet-50: Towards Real-Time Execution of all DNNs on Smartphone
|
With the rapid emergence of a spectrum of high-end mobile devices, many
applications that required desktop-level computation capability formerly can
now run on these devices without any problem. However, without a careful
optimization, executing Deep Neural Networks (a key building block of the
real-time video stream processing that is the foundation of many popular
applications) is still challenging, specifically, if an extremely low latency
or high accuracy inference is needed. This work presents CADNN, a programming
framework to efficiently execute DNN on mobile devices with the help of
advanced model compression (sparsity) and a set of thorough architecture-aware
optimization. The evaluation result demonstrates that CADNN outperforms all the
state-of-the-art dense DNN execution frameworks like TensorFlow Lite and TVM.
|
http://arxiv.org/abs/1905.00571v1
|
1905.00571
|
2019-05-02
|
computer-graphics
|
27.5-29.5 GHz Switched Array Sounder for Dynamic Channel Characterization: Design, Implementation and Measurements
|
A pre-requisite for the design of wireless systems is the understanding of the propagation channel. While a wealth of propagation knowledge exists for bands below 6 GHz, the same can not be said for bands approaching millimeter-wave frequencies. In this paper, we present the design, implementation and measurement-based verification of a re-configurable 27.5-29.5 GHz channel sounder for measuring dynamic directional channels. Based on the switched array principle, our design is capable of characterizing 128$\times$256 dual-polarized channels with snapshot times of around 600 ms. This is in sharp contrast to measurement times on the order of tens-of-minutes with rotating horn antenna sounders. Our design lends itself to high angular resolution at both link ends with calibrated antenna arrays sampled at 2$^\circ$ and 5$^\circ$ intervals in the azimuth and elevation domains. This is complemented with a bandwidth of up to 2 GHz, enabling nanosecond-level delay resolution. The short measurement times and stable radio frequency design facilitates real-time processing and averaging of the received wavefronts to gain measurement signal-to-noise ratio and dynamic range. After disclosing the sounder design and implementation, we demonstrate its capabilities by presenting dynamic and static measurements at 28 GHz over a 1 GHz bandwidth in an office corridor environment.
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https://arxiv.org/abs/2105.10712v1
|
2105.10712
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2021-05-22
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computer-graphics
|
275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10
|
Since 2014, NASA's K2 mission has observed large portions of the ecliptic
plane in search of transiting planets and has detected hundreds of planet
candidates. With observations planned until at least early 2018, K2 will
continue to identify more planet candidates. We present here 275 planet
candidates observed during Campaigns 0-10 of the K2 mission that are orbiting
stars brighter than 13 mag (in Kepler band) and for which we have obtained
high-resolution spectra (R = 44,000). These candidates are analyzed using the
VESPA package (Morton 2012, 2015b) in order to calculate their false-positive
probabilities (FPP). We find that 149 candidates are validated with an FPP
lower than 0.1%, 39 of which were previously only candidates and 56 of which
were previously undetected. The processes of data reduction, candidate
identification, and statistical validation are described, and the demographics
of the candidates and newly validated planets are explored. We show tentative
evidence of a gap in the planet radius distribution of our candidate sample.
Comparing our sample to the Kepler candidate sample investigated by Fulton et
al. (2017), we conclude that more planets are required to quantitatively
confirm the gap with K2 candidates or validated planets. This work, in addition
to increasing the population of validated K2 planets by nearly 50% and
providing new targets for follow-up observations, will also serve as a
framework for validating candidates from upcoming K2 campaigns and the
Transiting Exoplanet Survey Satellite, expected to launch in 2018.
|
http://arxiv.org/abs/1802.05277v2
|
1802.05277
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2018-03-26
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computer-graphics
|
2.75D: Boosting learning by representing 3D Medical imaging to 2D features for small data
|
In medical-data driven learning, 3D convolutional neural networks (CNNs) have started to show superior performance to 2D CNNs in numerous deep learning tasks, proving the added value of 3D spatial information in feature representation. However, the difficulty in collecting more training samples to converge, more computational resources and longer execution time make this approach less applied. Also, applying transfer learning on 3D CNN is challenging due to a lack of publicly available pre-trained 3D models. To tackle these issues, we proposed a novel 2D strategical representation of volumetric data, namely 2.75D. In this work, the spatial information of 3D images is captured in a single 2D view by a spiral-spinning technique. As a result, 2D CNN networks can also be used to learn volumetric information. Besides, we can fully leverage pre-trained 2D CNNs for downstream vision problems. We also explore a multi-view 2.75D strategy, 2.75D 3 channels (2.75Dx3), to boost the advantage of 2.75D. We evaluated the proposed methods on three public datasets with different modalities or organs (Lung CT, Breast MRI, and Prostate MRI), against their 2D, 2.5D, and 3D counterparts in classification tasks. Results show that the proposed methods significantly outperform other counterparts when all methods were trained from scratch on the lung dataset. Such performance gain is more pronounced with transfer learning or in the case of limited training data. Our methods also achieved comparable performance on other datasets. In addition, our methods achieved a substantial reduction in time consumption of training and inference compared with the 2.5D or 3D method.
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https://arxiv.org/abs/2002.04251v3
|
2002.04251
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2020-02-11
|
computer-graphics
|
$^{27}$Al NMR spectroscopic and DFT computational study of the quadrupole coupling of aluminium in two polymorphs of the complex aluminium hydride CsAlH4
|
The quadrupole coupling constant $C_{\text{Q}}$ and the asymmetry parameter $\eta$ of the aluminium nuclei in two polymorphs of the complex aluminium hydride CsAlH4 are determined from both $^{27}$Al MAS NMR spectra and $^{27}$Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The accuracy with which these parameters can be determined from the static spectra (CsAlH4(o): $C_{\text{Q}}=(1.42\pm0.01)$ MHz, $\eta=(0.62\pm0.01)$ and CsAlH4(t): $C_{\text{Q}}=(1.43\pm0.02)$ MHz, $\eta<0.03$) seems to be slightly higher than via the MAS approach. The experimentally determined parameters ($\delta_{\text{iso}}$, $C_{\text{Q}}$ and $\eta$) are compared with those obtained from DFT-GIPAW (density functional theory - gauge-including projected augmented wave) calculations. When using DFT-optimized structures, the magnitude of the quadrupole coupling constant is overestimated by about 45% for both polymorphs. Further calculations in which the geometry of the AlH4 tetrahedra was varied show a high sensitivity of $C_{\text{Q}}$ on the H--Al--H angles in particular. Modest changes in the angles on the order of one to three degrees are sufficient to achieve near-perfect agreement between GIPAW calculations and experiment. The deviations found for the DFT-optimized structures are explained with the neglect of thermal motion, which typically leads to a reduction of distortions of the AlH4 tetrahedra. From a broader perspective, the uncertainty in the positions of the hydrogen atoms renders the accurate reproduction or prediction of quadrupole coupling constants for aluminium hydrides challenging.
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https://arxiv.org/abs/2410.07731v1
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2410.07731
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2024-10-10
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computer-graphics
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$^{27}$Al NMR study of the magnetic Weyl semimetal CeAlGe
|
Motivated by the recent observations of electronic correlation effect [M. Corasaniti \textit{et al}., Phys. Rev. B \textbf{104}, L121112 (2021)] and topology-stabilized magnetic fluctuations [N. Drucker \textit{et al}., Nat. Commun. \textbf{14}, 5182 (2023)] in the noncentrosymmetric magnetic Weyl semimetal candidate CeAlGe, we performed systematic studies on the local static and dynamic spin susceptibilities by $^{27}$Al nuclear magnetic resonance. Due to the large spin susceptibility from Ce-$4f$ electrons, the theoretically predicted responses from Weyl fermions are overwhelmed. A Knight-shift anomaly is observed below $T^*\sim50$ K, a signature of the onset of coherent Kondo coupling. In addition, an anomalous peak is found in $1/T_1T$ near 15 K, well above the magnetic ordering temperature $T_N \approx 5$ K, which probably is a consequence of topology-stabilized magnetic fluctuations. These results highlight the interplay among electronic correlation, magnetism and band topology in this family of Kondo Weyl semimetals.
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https://arxiv.org/abs/2403.06476v2
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2403.06476
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2024-03-11
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computer-graphics
|
27Al-NMR Study on a square-Kagome lattice antiferromagnet
|
NMR study has been performed on an S = 1/2 antiferromagnet KCu6AlBiO4(SO4)5Cl on the square-Kagome lattice, which has three slightly inequivalent nearest-neighbor interactions. Because of the geometrical frustration inherited from triangles within the square kagome lattice and of the low dimensionality, a long range magnetic order is strongly suppressed; its absence has so far been confirmed in low temperatures down to dilution refrigerator region. 27Al-NMR spectra and the longitudinal relaxation time T1 were measured by a conventional pulsed spectrometer on powder sample under several magnetic fields between 3 and 10 T and in low temperatures down to 0.35 K. The NMR line width due to the inhomogeneous broadening increased with lowering temperatures and leveled off below 3 K, where FWHM reached the value as large as 0.1 T, implying that the ground state is magnetic one, consistent with previous reports. On the other hand, the longitudinal nuclear spin relaxation rate 1/T1 obeyed the Arrhenius law with the thermal activation energy {\Delta} = 2K at low temperatures, suggesting that a small gap is formed in the spin excitation spectrum.
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https://arxiv.org/abs/2402.18125v1
|
2402.18125
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2024-02-28
|
computer-graphics
|
27-day variation of the GCR intensity based on corrected and uncorrected for geomagnetic disturbances data of neutron monitors
|
We study 27-day variations of the galactic cosmic ray (GCR) intensity for
2005- 2008 period of the solar cycle #23. We use neutron monitors (NMs) data
corrected and uncorrected for geomagnetic disturbances. Besides the limited
time intervals when the 27-day variations are clearly established, always exist
some feeble 27-day variations in the GCR 5 intensity related to the constantly
present weak heliolongitudinal asymmetry in the heliosphere. We calculate the
amplitudes of the 27-day variation of the GCR intensity based on the NMs data
corrected and uncorrected for geomagnetic disturbances. We show that these
amplitudes do not differ for NMs with cut-off rigidities smaller than 4-5 GV
comparing with NMs of higher cut-off rigidities. Rigidity spectrum of the
27-day variation of the GCR intensity found in the uncorrected data is soft
while it is hard in the case of the corrected data. For both cases exists
definite tendency of softening the temporal changes of the 27-day variation's
rigidity spectrum in period of 2005 to 2008 approaching the minimum of solar
activity. We believe that a study of the 27-day variation of the GCR intensity
based on the data uncorrected for geomagnetic disturbances should be carried
out by NMs with cut-off rigidities smaller than 4-5 GV.
|
http://arxiv.org/abs/1509.05738v1
|
1509.05738
|
2015-09-18
|
computer-graphics
|
27-day Variation of the Three Dimensional Solar Anisotropy of Galactic Cosmic Ray: 1965-2014
|
The temporal evaluation of the 27-day variation of the three dimensional (3D)
galactic cosmic ray (GCR) anisotropy has been studied for 1965-2014. 3D
anisotropy vector was obtained based on the neutron monitors and Nagoya muon
telescopes data. We analyze the 27-day variation of the (1) two dimensional
(2D) GCR anisotropy in the ecliptic plane, and (2) north-south anisotropy
normal to the ecliptic plane. Studying the time line of the 27-day variation of
the 2D GCR anisotropy, we confirm that the average amplitude in the minimum
epoch of solar activity is polarity dependent, as it is expected from the drift
theory. The amplitude in the negative polarity epochs is less as we had shown
before. The feeble 11-year variation connected with solar cycle and strong
22-year pattern connected with solar magnetic cycle is visible in the 27-day
variation of the 2D anisotropy for 1965-2014. We show that the 27-day variation
of the GG index (being a measure of the north-south asymmetry) varies in
accordance to solar cycle with a period of 11-years, being in good agreement
with the 27-day variation of the At component of the GCR anisotropy calculated
by the IZMIRAN group. Detailed analysis are presented for the solar minimum
2007-2008 of solar cycle no.23 and solar maximum 2013-2015 of solar cycle no
24. In the solar cycle no. 24 GG index, calculated by Nagoya telescopes data,
is highly anticorrelated with By component of the interplanetary magnetic field
(IMF) and shows a clear recurrent changes related to the Sun's rotation.
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http://arxiv.org/abs/1509.05770v1
|
1509.05770
|
2015-09-18
|
computer-graphics
|
2.7-octave supercontinuum generation spanning from ultraviolet to near-infrared in thin-film lithium niobate waveguides
|
Supercontinuum generation (SCG) with spectral coverage across the full visible and ultraviolet (UV) ranges is crucial for optical clocks, quantum computing and sensing. However, achieving such SCG in nanophotonic platforms is challenging due to the difficulties in spectrum broadening. Here, Such ultrabroad-bandwidth SCG was demonstrated in thin-film lithium niobate (TFLN) nanophotonic waveguides by dispersion management, without periodic poling for spectral broadening. Anomalous-dispersion waveguides were designed in the telecom band, simultaneously enabling dispersive wave emergence, modal-matched second harmonic generation, and third harmonic generation for spectrum broadening. Moreover, MgO was intentionally doped to mitigate the photorefractive effect of lithium niobate, which frequently results in un-sustained spectrum broadening and in turn limits the accessible SCG coverage. By leveraging photolithography assisted chemo-mechanical etching, low-loss MgO doped TFLN nanophotonic waveguides were fabricated. As a result, thanks to the utilization of the strong second-order and third-order nonlinear processes, gap-free 2.7-octave SCG spanning from 330 nm to 2250 nm was observed by pumping the waveguide with a 1550-nm femtosecond pulsed laser with 0.687 nJ, agreeing well with numerical simulation. This spectral coverage represents the state of the art in TFLN platforms without fine microdomains, and even close to the record in sophisticated chirped periodically poled TFLN waveguides.
|
https://arxiv.org/abs/2505.12438v1
|
2505.12438
|
2025-05-18
|
computer-graphics
|
27 Open Problems in Kolmogorov Complexity
|
The paper proposes open problems in classical Kolmogorov complexity. Each problem is presented with background information and thus the article also surveys some recent studies in the area.
|
https://arxiv.org/abs/2203.15109v1
|
2203.15109
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2022-03-28
|
computer-graphics
|
$27 \otimes 27$
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We study the decomposition into $SU(N)$ irreducible representations (irreps) of the tensor product $27 \otimes 27$, where $27$ is the highest-dimensional $SU(N)$ irrep present in a two-gluon system, and explicitly construct all Hermitian projectors on these irreps, as well as transition operators between them. This yields an explicit basis of the complete $27\otimes 27$ color space (defined as the space of $27\otimes 27\to 27 \otimes 27$ color maps) in terms of orthogonal multiplets. This study shows that even complex color structures can be addressed, with the help of the birdtrack pictorial technique, using only elementary tools. In particular, we highlight the usefulness of the quadratic Casimir operator, whose eigenspaces allow efficient filtering of all projectors and transition operators, and of the permutation operators that further improve this filtering. The product $27\otimes 27$ also has an interesting feature: three equivalent irreps $27$ appear in the decomposition, two of which are symmetric and can therefore be distinguished neither by the quadratic Casimir operator nor by their symmetry under permutation. In this case, it is convenient to use Clebsch-Gordan coefficients to derive the two associated, symmetric projectors. The latter are not uniquely determined (only their sum is), and we give the set of all solutions. Finally, we explicitly derive the soft anomalous dimension matrix associated with $27\otimes 27\to 27\otimes 27$, whose block-diagonal main structure is easy to understand, but whose detailed spectrum properties remain intriguing. The approach presented for $27 \otimes 27 \to 27 \otimes 27$ could in principle be applied to any product of $SU(N)$ irreps, and eventually automated.
|
https://arxiv.org/abs/2504.11362v1
|
2504.11362
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2025-04-15
|
computer-graphics
|
$^{27}\text{Al }$ NMR chemical shift of $\text{Al}(\text{OH})_{4}^{-}$ from first principles. Assessment of error cancellation in NMR chemical shift computations in chemically distinct reference and targeted systems
|
Predicting accurate NMR chemical shieldings relies upon cancellation of
different types of error in the ab initio methodology used to calculate the
shielding tensor of the analyte of interest and the reference. Often the
intrinsic error in computed shieldings due to basis sets, approximations in the
Hamiltonian, description of the wave function, and dynamic effects, is nearly
identical between the analyte and reference, yet if the electronic structure or
sensitivity to local environment differs dramatically, this cannot be taken for
granted. Detailed prior work has examined the octahedral trivalent cation
$\text{Al}(\text{H}_{2}\text{O})_{6}^{3+}$ , accounting for ab initio intrinsic
errors. However, the fact that this analyte is used as a reference for the
chemically distinct tetrahedral anion $\text{Al}(\text{OH})_{4}^{-}$ inspires
the study of how these errors cancel in an attempt to understand the limits of
predictive capability for accurately determining $^{27}\text{Al }$ shielding in
$\text{Al}(\text{OH})_{4}^{-}$. In this work, we estimate the absolute
shielding of $^{27}\text{Al }$ nucleus in $\text{Al}(\text{OH})_{4}^{-}$ at the
coupled cluster level (515.1 $\pm$ 5.3 ppm). Shielding sensitivity to the
choice of method approximation and atomic basis sets treatment has been
evaluated. Solvent and thermal effects are assessed through ensemble averaging
techniques using ab-initio molecular dynamics. The contribution of each type of
intrinsic error is assessed for $\text{Al}(\text{H}_{2}\text{O})_{6}^{3+}$ and
$\text{Al}(\text{OH})_{4}^{-}$ ions, revealing significant differences that
fundamentally hamper the ability to accurately calculate the $^{27}\text{Al }$
chemical shift of $\text{Al}(\text{OH})_{4}^{-}$ from first principles.
|
http://arxiv.org/abs/2001.00107v1
|
2001.00107
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2019-12-31
|
computer-graphics
|
280 Birds with One Stone: Inducing Multilingual Taxonomies from Wikipedia using Character-level Classification
|
We propose a simple, yet effective, approach towards inducing multilingual
taxonomies from Wikipedia. Given an English taxonomy, our approach leverages
the interlanguage links of Wikipedia followed by character-level classifiers to
induce high-precision, high-coverage taxonomies in other languages. Through
experiments, we demonstrate that our approach significantly outperforms the
state-of-the-art, heuristics-heavy approaches for six languages. As a
consequence of our work, we release presumably the largest and the most
accurate multilingual taxonomic resource spanning over 280 languages.
|
http://arxiv.org/abs/1704.07624v2
|
1704.07624
|
2017-04-25
|
computer-graphics
|
280 GHz Focal Plane Unit Design and Characterization for the SPIDER-2 Suborbital Polarimeter
|
We describe the construction and characterization of the 280 GHz bolometric
focal plane units (FPUs) to be deployed on the second flight of the
balloon-borne SPIDER instrument. These FPUs are vital to SPIDER's primary
science goal of detecting or placing an upper limit on the amplitude of the
primordial gravitational wave signature in the cosmic microwave background
(CMB) by constraining the B-mode contamination in the CMB from Galactic dust
emission. Each 280 GHz focal plane contains a 16 x 16 grid of corrugated
silicon feedhorns coupled to an array of aluminum-manganese transition-edge
sensor (TES) bolometers fabricated on 150 mm diameter substrates. In total, the
three 280 GHz FPUs contain 1,530 polarization sensitive bolometers (765 spatial
pixels) optimized for the low loading environment in flight and read out by
time-division SQUID multiplexing. In this paper we describe the mechanical,
thermal, and magnetic shielding architecture of the focal planes and present
cryogenic measurements which characterize yield and the uniformity of several
bolometer parameters. The assembled FPUs have high yields, with one array as
high as 95% including defects from wiring and readout. We demonstrate high
uniformity in device parameters, finding the median saturation power for each
TES array to be ~3 pW at 300 mK with a less than 6% variation across each array
at one standard deviation. These focal planes will be deployed alongside the 95
and 150 GHz telescopes in the SPIDER-2 instrument, slated to fly from McMurdo
Station in Antarctica in December 2018.
|
http://arxiv.org/abs/1711.04169v2
|
1711.04169
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2017-11-22
|
computer-graphics
|
2, 84, 30, 993, 560, 15456, 11962, 261485, ...: Higher dimension operators in the SM EFT
|
In a companion paper, we show that operator bases for general effective field
theories are controlled by the conformal algebra. Equations of motion and
integration by parts identities can be systematically treated by organizing
operators into irreducible representations of the conformal group. In the
present work, we use this result to study the standard model effective field
theory (SM EFT), determining the content and number of higher dimension
operators up to dimension 12, for an arbitrary number of fermion generations.
We find additional operators to those that have appeared in the literature at
dimension 7 (specifically in the case of more than one fermion generation) and
at dimension 8.
(The title sequence is the total number of independent operators in the SM
EFT with one fermion generation, including hermitian conjugates, ordered in
mass dimension, starting at dimension 5.)
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http://arxiv.org/abs/1512.03433v2
|
1512.03433
|
2019-08-23
|
computer-graphics
|
$^{28}$Al Half-life Measurement and the negative mirror asymmetry between the $^{28}$Al($β^-$)$^{28m}$Si and $^{28}$P($β^+$)$^{28m}$Si decays
|
In the past, the mirror asymmetry parameter has been proposed as a probing mechanism for the presence of beyond the Standard Model second-class currents in nuclear beta decay transitions. However, this was hindered by large uncertainties in the required nuclear structure correction terms. Recently, a new calculation of these corrections attempted, but could not fully explain the negative mirror asymmetry between the $^{28}$Al($\beta^-$)$^{28m}$Si and $^{28}$P($\beta^+$)$^{28m}$Si decays. To put the mirror asymmetry parameter on a more solid footing, the half-life of $^{28}$Al was measured for the first time using a radioactive ion beam at the Nuclear Science Laboratory of the University of Notre Dame. The new result, $t_{1/2}=$134.432(34) s, is consistent with most of the past data except for one highly discrepant measurement. The new mirror asymmetry parameter of -3.5(10)$\%$ obtained still does not agree with nuclear structure calculations.
|
https://arxiv.org/abs/2505.01722v1
|
2505.01722
|
2025-05-03
|
computer-graphics
|
28 GHz Indoor and Outdoor Propagation Analysis at a Regional Airport
|
In the upcoming 5G communication, the millimeter-wave (mmWave) technology will play an important role due to its large bandwidth and high data rate. However, mmWave frequencies have higher free-space path loss (FSPL) in line-of-sight (LOS) propagation compared to the currently used sub-6 GHz frequencies. What is more, in non-line-of-sight (NLOS) propagation, the attenuation of mmWave is larger compared to the lower frequencies, which can seriously degrade the performance. It is therefore necessary to investigate mmWave propagation characteristics for a given deployment scenario to understand coverage and rate performance for that environment. In this paper, we focus on 28 GHz wideband mmWave signal propagation characteristics at Johnston Regional Airport (JNX), a local airport near Raleigh, NC. To collect data, we use an NI PXI based channel sounder at 28 GHz for indoor, outdoor, and indoor-to-outdoor scenarios. Results on LOS propagation, reflection, penetration, signal coverage, and multi-path components (MPCs) show a lower indoor FSPL, a richer scattering, and a better coverage compared to outdoor. We also observe high indoor-to-outdoor propagation losses.
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https://arxiv.org/abs/2101.02599v1
|
2101.02599
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2021-01-07
|
computer-graphics
|
28 GHz Millimeter-Wave Ultrawideband Small-Scale Fading Models in Wireless Channels
|
This paper presents small-scale fading measurements for 28 GHz outdoor
millimeter-wave ultrawideband channels using directional horn antennas at the
transmitter and receiver. Power delay profiles were measured at half-wavelength
spatial increments over a local area (33 wavelengths) on a linear track in two
orthogonal receiver directions in a typical base-to-mobile scenario with fixed
transmitter and receiver antenna beam pointing directions. The voltage path
amplitudes are shown to follow a Rician distribution, with K-factor ranging
from 9 - 15 dB and 5 - 8 dB in line of sight (LOS) and non-line of sight (NLOS)
for a vertical-to-vertical co-polarized antenna scenario, respectively, and
from 3 - 7 dB in both LOS and NLOS vertical-to-horizontal cross-polarized
antenna scenario. The average spatial autocorrelation functions of individual
multipath components reveal that signal amplitudes reach a correlation of 0
after 2 and 5 wavelengths in LOS and NLOS co-polarized V-V antenna scenarios.
The models provided are useful for recreating path gain statistics of
millimeter-wave wideband channel impulse responses over local areas, for the
study of multi-element antenna simulations and channel estimation algorithms.
|
http://arxiv.org/abs/1511.06938v2
|
1511.06938
|
2016-02-22
|
computer-graphics
|
28 GHz mmWave Channel Measurements and Modeling in a Library Environment
|
To fully exploit the millimeter-wave bands for the fifth generation cellular
systems, an accurate understanding of the channel propagation characteristics
is required, and hence extensive measurement campaigns in different
environments are needed. In this paper, we use a rotated directional
antenna-based channel sounder for measurements at 28 GHz in large indoor
environments at a library setting. We present models for power angular-delay
profile and large-scale path loss based on the measurements over distances
ranging from 10 m to 50 m. In total, nineteen different line-of-sight (LOS) and
non-line-of-sight (NLOS) scenarios are considered, including the cases where
the transmitter and the receiver are placed on different floors. Results show
that the close-in free space reference distance and the floating intercept path
loss models both perform well in fitting the empirical data. The path loss
exponent obtained for the LOS scenarios is found to be very close to that of
the free space path loss model.
|
http://arxiv.org/abs/1910.08632v1
|
1910.08632
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2019-10-18
|
computer-graphics
|
28 GHz NLOS Channel Measurements Revealing Low Path Loss and High Angular Spread in Container Ports
|
This paper presents results from a comprehensive measurement campaign conducted at 28 GHz inside a container canyon within a commercial port environment. The measurements are performed at various points inside the container canyon, considering two types of container stacking and two different Transmitter (TX) locations, using a narrowband channel sounder equipped with a rotating horn antenna. The measurements are used to evaluate the azimuthal spectrum and spatial correlation, as well as the impact of a vehicle inside a canyon on these parameters. Further, the measurement data is utilized to validate a simulation setup from which the path loss and the elevation spectrum inside the canyon is obtained. Lastly, a propagation model inside the canyon is hypothesized and shown to be consistent with the measurements. The analysis show a low path loss compared to free space, as well as a high angular spread and short spatial correlation.
|
https://arxiv.org/abs/2309.02810v1
|
2309.02810
|
2023-09-06
|
computer-graphics
|
28 GHz Phased Array-Based Self-Interference Measurements for Millimeter Wave Full-Duplex
|
We present measurements of the 28 GHz self-interference channel for full-duplex sectorized multi-panel millimeter wave (mmWave) systems, such as integrated access and backhaul. We measure the isolation between the input of a transmitting phased array panel and the output of a co-located receiving phased array panel, each of which is electronically steered across a number of directions in azimuth and elevation. In total, nearly 6.5 million measurements were taken in an anechoic chamber to densely inspect the directional nature of the coupling between 256-element phased arrays. We observe that highly directional mmWave beams do not necessarily offer widespread high isolation between transmitting and receiving arrays. Rather, our measurements indicate that steering the transmitter or receiver away from the other tends to offer higher isolation but even slight steering changes can lead to drastic variations in isolation. These measurements can be useful references when developing mmWave full-duplex solutions and can motivate a variety of future topics including beam/user selection and beamforming codebook design.
|
https://arxiv.org/abs/2203.02809v1
|
2203.02809
|
2022-03-05
|
computer-graphics
|
28nm Fully-Depleted SOI Technology: Cryogenic Control Electronics for Quantum Computing
|
This paper reports the first cryogenic characterization of 28nm
Fully-Depleted-SOI CMOS technology. A comprehensive study of digital/analog
performances and body-biasing from room to the liquid helium temperature is
presented. Despite a cryogenic operation, effectiveness of body-biasing remains
unchanged and provides an excellent $V_{TH}$ controllability. Low-temperature
operation enables higher drive current and a largely reduced subthreshold swing
(down to 7mV/dec). FDSOI can provide a valuable approach to cryogenic low-power
electronics. Applications such as classical control hardware for quantum
processors are envisioned.
|
http://arxiv.org/abs/2002.07070v1
|
2002.07070
|
2019-12-20
|
computer-graphics
|
28 THz soliton frequency comb in a continuous-wave pumped fiber Fabry-Perot resonator
|
We report the generation of an optical frequency comb featuring 28 THz bandwidth, sustained by a single 80 fs cavity soliton recirculating in a fiber Fabry-Perot resonator. This large spectrum is comparable to frequency combs obtained with microresonators operating in the anomalous dispersion regime. Thanks to the compact design and the easy coupling of the resonator, cavity solitons can be generated in an all-fiber experimental setup with a continuous wave pumping scheme. We also observe the generation of a dispersive wave at higher frequencies which is supported by higher-order dispersion. These observations align remarkably well with both numerical simulations and the established theory of cavity solitons.
|
https://arxiv.org/abs/2401.12858v1
|
2401.12858
|
2024-01-23
|
computer-graphics
|
2900 square degree search for the optical counterpart of short gamma-ray burst GRB 180523B with the Zwicky Transient Facility
|
There is significant interest in the models for production of short gamma-ray
bursts. Until now, the number of known short gamma-ray bursts with
multi-wavelength afterglows has been small. While the {\it Fermi} Gamma-Ray
Burst Monitor detects many gamma-ray bursts relative to the Neil Gehrels {\it
Swift} Observatory, the large localization regions makes the search for
counterparts difficult. With the Zwicky Transient Facility recently achieving
first light, it is now fruitful to use its combination of depth ($m_\textrm{AB}
\sim 20.6$), field of view ($\approx$ 47 square degrees), and survey cadence
(every $\sim 3$ days) to perform Target of Opportunity observations. We
demonstrate this capability on GRB 180523B, which was recently announced by the
{\it Fermi} Gamma-Ray Burst Monitor as a short gamma-ray burst. ZTF imaged
$\approx$ 2900\,square degrees of the localization region, resulting in the
coverage of 61.6\,\% of the enclosed probability over 2 nights to a depth of
$m_\textrm{AB} \sim 20.5$. We characterized 14 previously unidentified
transients, and none were found to be consistent with a short gamma-ray burst
counterpart. This search with the Zwicky Transient Facility shows it is an
efficient camera for searching for coarsely-localized short gamma-ray burst and
gravitational-wave counterparts, allowing for a sensitive search with minimal
interruption to its nominal cadence.
|
http://arxiv.org/abs/1901.11385v1
|
1901.11385
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2019-01-31
|
computer-graphics
|
29P/Schwassmann-Wachmann 1, A Centaur in the Gateway to the Jupiter-Family Comets
|
Jupiter-family comets (JFCs) are the evolutionary products of trans-Neptunian
objects (TNOs) that evolve through the giant planet region as Centaurs and into
the inner solar system. Through numerical orbital evolution calculations
following a large number of TNO test particles that enter the Centaur
population, we have identified a short-lived dynamical Gateway, a temporary
low-eccentricity region exterior to Jupiter through which the majority of JFCs
pass. We apply an observationally based size distribution function to the known
Centaur population and obtain an estimated Gateway region population. We then
apply an empirical fading law to the rate of incoming JFCs implied by the the
Gateway region residence times. Our derived estimates are consistent with
observed population numbers for the JFC and Gateway populations. Currently, the
most notable occupant of the Gateway region is 29P/Schwassmann-Wachmann 1
(SW1), a highly active, regularly outbursting Centaur. SW1's present-day,
very-low-eccentricity orbit was established after a 1975 Jupiter conjunction
and will persist until a 2038 Jupiter conjunction doubles its eccentricity and
pushes its semi-major axis out to its current aphelion. Subsequent evolution
will likely drive SW1's orbit out of the Gateway region, perhaps becoming one
of the largest JFCs in recorded history. The JFC Gateway region coincides with
a heliocentric distance range where the activity of observed cometary bodies
increases significantly. SW1's activity may be typical of the early
evolutionary processing experienced by most JFCs. Thus, the Gateway region, and
its most notable occupant SW1, are critical to both the dynamical and physical
transition between Centaurs and JFCs.
|
http://arxiv.org/abs/1908.04185v2
|
1908.04185
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2019-09-12
|
computer-graphics
|
29P/Schwassmann-Wachmann: A Rosetta Stone for Amorphous Water Ice and CO <-> CO2 Conversion in Centaurs and Comets?
|
Centaur 29P/Schwassmann-Wachmann 1 (SW1) is a highly active object orbiting in the transitional Gateway region (Sarid et al. 2019) between the Centaur and Jupiter Family Comet regions. SW1 is unique among the Centaurs in that it experiences quasi-regular major outbursts and produces CO emission continuously; however, the source of the CO is unclear. We argue that due to its very large size (approx. 32 km radius), SW1 is likely still responding, via amorphous water ice (AWI) conversion to crystalline water ice (CWI), to the rapid change in its external thermal environment produced by its dynamical migration from the Kuiper belt to the Gateway Region at the inner edge of the Centaur region at 6 au. It is this conversion process that is the source of the abundant CO and dust released from the object during its quiescent and outburst phases. If correct, these arguments have a number of important predictions testable via remote sensing and in situ spacecraft characterization, including: the quick release on Myr timescales of CO from AWI conversion for any few km-scale scattered disk KBO transiting into the inner system; that to date SW1 has only converted between 50 to 65% of its nuclear AWI to CWI; that volume changes upon AWI conversion could have caused subsidence and cave-ins, but not significant mass wasting or crater loss on SW1; that SW1s coma should contain abundant amounts of CWI CO2-rich icy dust particles; and that when SW1 transits into the inner system within the next 10,000 years, it will be a very different kind of JFC comet.
|
https://arxiv.org/abs/2209.09136v2
|
2209.09136
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2022-09-19
|
computer-graphics
|
2ACT: AI-Accentuated Career Transitions via Skill Bridges
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This study introduces the AI-Accentuated Career Transitions framework, advancing beyond binary automation narratives to examine how distinct AI usage patterns reshape occupational mobility. Analyzing 545 occupations through multivariate modeling, we identify six qualitatively distinct human-AI usage patterns that differentially predict placement across job preparation zones. Our findings empirically validate the "missing middle" hypothesis: automation-focused usage strongly predicts lower job zone placement while augmentative usage predicts higher zones. Most significantly, we identify specific Knowledge, Skill, and Abilities combinations with AI usage patterns that function as "skill bridges" facilitating upward mobility. The interaction between task iteration AI usage and cognitive skills emerges as the strongest advancement predictor, creating pathways across traditionally disconnected occupational categories. Counterintuitively, despite directive AI's negative main effect, its interaction with technical knowledge positively predicts advancement in specialized domains. Comparative model testing confirms that AI usage patterns represent a distinct dimension of occupational classification that adds significant explanatory power beyond traditional skill measures. These findings reveal AI as a skill amplifier that widens capability gaps rather than an equalizing force. The 2ACT framework provides strategic guidance for workers, curriculum designers, policymakers, and organizations navigating increasingly AI-mediated career pathways.
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https://arxiv.org/abs/2505.07914v1
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2505.07914
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2025-05-12
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computer-graphics
|
2-adic Galois images of non-CM isogeny-torsion graphs
|
Let $\mathcal{E}$ be a $\mathbb{Q}$-isogeny class of elliptic curves defined over $\mathbb{Q}$ without CM. The isogeny graph associated to $\mathcal{E}$ is a graph which has a vertex for each elliptic curve in $\mathcal{E}$ and an edge for each $\mathbb{Q}$-isogeny of prime degree that maps one elliptic curve in $\mathcal{E}$ to another elliptic curve in $\mathcal{E}$, with the degree recorded as a label of the edge. An isogeny-torsion graph is an isogeny graph where, in addition, we label each vertex with the abstract group structure of the torsion subgroup over $\mathbb{Q}$ of the corresponding elliptic curve. Then, the main statement of the article is a classification of the $2$-adic image of Galois that occurs at each vertex of all isogeny-torsion graphs consisting of elliptic curves defined over $\mathbb{Q}$ without CM.
|
https://arxiv.org/abs/2302.06094v2
|
2302.06094
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2023-02-13
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computer-graphics
|
2-adic images of CM isogeny-torsion graphs
|
Let $\mathcal{E}$ be a $\mathbb{Q}$-isogeny class of elliptic curves defined over $\mathbb{Q}$. The isogeny graph associated to $\mathcal{E}$ is a graph which has a vertex for each element of $\mathcal{E}$ and an edge for each $\mathbb{Q}$-isogeny of prime degree that maps one elliptic curve in $\mathcal{E}$ to another elliptic curve in $\mathcal{E}$, with the degree of the isogeny recorded as a label of the edge. The isogeny-torsion graph associated to $\mathcal{E}$ is the isogeny graph associated to $\mathcal{E}$ where, in addition, we label each vertex with the abstract group structure of the torsion subgroup over $\mathbb{Q}$ of the corresponding elliptic curve. The main result of the article is a classification of the 2-adic Galois image at each vertex of the isogeny-torsion graphs whose associated $\mathbb{Q}$-isogeny class consists of elliptic curves over $\mathbb{Q}$ with complex multiplication.
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https://arxiv.org/abs/2208.11649v2
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2208.11649
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2022-08-24
|
computer-graphics
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$2$-adic integral models of some Shimura varieties with parahoric level structure
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We construct integral models over $p=2$ for some Shimura varieties of abelian type with parahoric level structure, extending the previous work of Kim-Madapusi, Kisin, Pappas, and Zhou. For Shimura varieties of Hodge type, we show that our integral models are canonical in the sense of Pappas-Rapoport.
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https://arxiv.org/abs/2301.12981v2
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2301.12981
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2023-01-25
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computer-graphics
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2-adic point counting on $K3$ surfaces
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This article reports on an approach to point counting on algebraic varieties over finite fields that is based on a detailed investigation of the $2$-adic orthogonal group. Combining the new approach with a $p$-adic method, we count the number of points on some $K3$ surfaces over the field $\bbF_{\!p}$, for all primes $p < 10^8$.
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https://arxiv.org/abs/2202.10853v2
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2202.10853
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2022-02-22
|
computer-graphics
|
2-Adic quantum mechanics, continuous-time quantum walks, and the space discreteness
|
Using techniques of p-adic analysis, it is possible to formulate a rigorous version of the quantum mechanics (QM), in the sense of Dirac-von Neumann, consistent with the existence of the Planck length. Such a model cannot be formulated if we use R^{3} as a model for physical space. The experimental testability of physical theories at the Planck scale is currently impossible. Here, we provide an indirect, theoretical argument that shows that the p-adic QM has physical content. We show that a large class of Schr\"odinger equations describes the scaling limits of continuous-time quantum walks on graphs (stochastic automata). These quantum walks appear as fundamental tools in quantum computing. We conjecture that this interpretation is valid in a general framework. The `new theory' does not have Lorentz symmetry, and the Einstein causality is violated. This fact does not contradict the so-called no-communication theorem; such a result requires as a primary hypothesis that R^{4} be a valid model for space-time at the Planck scale. Thus, the no-communication theorem under the discreteness of the space is an open problem.
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https://arxiv.org/abs/2502.16416v1
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2502.16416
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2025-02-23
|
computer-graphics
|
$2$-adic slopes of Hilbert modular forms over $\mathbb{Q}(\sqrt{5})$
|
We show that for arithmetic weights with a fixed finite order character, the
slopes of $U_p$ (for $p=2$) acting on overconvergent Hilbert modular forms of
level $U_0(4)$ are independent of the (algebraic part of the) weight and can be
obtained by a simple recipe from the classical slopes in parallel weight $3$.
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http://arxiv.org/abs/1811.04799v3
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1811.04799
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2020-05-10
|
computer-graphics
|
2-Adic Stratification of Totients
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In this paper we study the multiplicities and the asymptotic behaviour of the
numbers of totients in the strata given by 2-adic valuation.
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http://arxiv.org/abs/2005.05475v1
|
2005.05475
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2020-05-11
|
computer-graphics
|
2-adic Valuations of Quadratic Sequences
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Properties of 2-adic valuation sequences for general quadratic polynomials with integer coefficients are determined directly from the coefficients. These properties include boundedness or unboundedness, periodicity, and valuations at terminating nodes. We completely describe the periodic sequences in the bounded case. Throughout, we frame results in terms of trees and sequences.
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https://arxiv.org/abs/2012.10332v4
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2012.10332
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2020-12-18
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computer-graphics
|
2-adjoint equivalences in homotopy type theory
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We introduce the notion of (half) 2-adjoint equivalences in Homotopy Type Theory and prove their expected properties. We formalized these results in the Lean Theorem Prover.
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https://arxiv.org/abs/2008.12433v4
|
2008.12433
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2020-08-28
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computer-graphics
|
2AFC Prompting of Large Multimodal Models for Image Quality Assessment
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While abundant research has been conducted on improving high-level visual understanding and reasoning capabilities of large multimodal models~(LMMs), their visual quality assessment~(IQA) ability has been relatively under-explored. Here we take initial steps towards this goal by employing the two-alternative forced choice~(2AFC) prompting, as 2AFC is widely regarded as the most reliable way of collecting human opinions of visual quality. Subsequently, the global quality score of each image estimated by a particular LMM can be efficiently aggregated using the maximum a posterior estimation. Meanwhile, we introduce three evaluation criteria: consistency, accuracy, and correlation, to provide comprehensive quantifications and deeper insights into the IQA capability of five LMMs. Extensive experiments show that existing LMMs exhibit remarkable IQA ability on coarse-grained quality comparison, but there is room for improvement on fine-grained quality discrimination. The proposed dataset sheds light on the future development of IQA models based on LMMs. The codes will be made publicly available at https://github.com/h4nwei/2AFC-LMMs.
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https://arxiv.org/abs/2402.01162v1
|
2402.01162
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2024-02-02
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computer-graphics
|
$2^{\aleph_0}$ pairwise non-isomorphic maximal-closed subgroups of Sym$(\mathbb{N})$ via the classification of the reducts of the Henson digraphs
|
Given two structures $\mathcal{M}$ and $\mathcal{N}$ on the same domain, we
say that $\mathcal{N}$ is a reduct of $\mathcal{M}$ if all
$\emptyset$-definable relations of $\mathcal{N}$ are $\emptyset$-definable in
$\mathcal{M}$. In this article the reducts of the Henson digraphs are
classified. Henson digraphs are homogeneous countable digraphs that omit some
set of finite tournaments. As the Henson digraphs are $\aleph_0$-categorical,
determining their reducts is equivalent to determining all closed supergroups
$G<$ Sym$(\mathbb{N})$ of their automorphism groups.
A consequence of the classification is that there are $2^{\aleph_0}$ pairwise
non-isomorphic Henson digraphs which have no proper non-trivial reducts. Taking
their automorphisms groups gives a positive answer to a question of Macpherson
that asked if there are $2^{\aleph_0}$ pairwise non-conjugate maximal-closed
subgroups of Sym$(\mathbb{N})$. By the reconstruction results of Rubin, these
groups are also non-isomorphic as abstract groups.
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http://arxiv.org/abs/1509.07674v1
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1509.07674
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2015-09-25
|
computer-graphics
|
2$\alpha$+$t$ cluster structure in $^{11}$B
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The 2$\alpha+t$ cluster structure in $^{11}$B is investigated by the
microscopic generator coordinate method (GCM) with the Brink cluster wave
functions. With a proper choice of the parameters of the effective interaction,
the calculated energy spectrum shows reasonable agreement with the observed
low-lying spectra of both parities. On the basis of the calculated radii,
monopole and $B(E2)$ transition strengths, several developed cluster states of
$^{11}$B are suggested. For the negative-parity states, in addition to the
well-known $3/2_3^-$ cluster state, the $1/2_2^-$ and $5/2_3^-$ states are also
proposed as the well-developed cluster states. For the positive-parity states,
it is found that many states around the 2$\alpha+t$ threshold show the feature
of developed clusters. In particular, the $1/2_2^+$ state is found to have a
linear-chain-like structure, which is consistent with the previous
antisymmetrized molecular dynamics calculation, but contradicts to the
orthogonality condition model calculation. It is also found that many of these
positive-parity cluster candidates have the non-negligible isoscalar dipole
transition strengths, which require the experimental confirmation.
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http://arxiv.org/abs/1711.04439v1
|
1711.04439
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2017-11-13
|
computer-graphics
|
2- and 3-Covariant Equiangular Tight Frames
|
Equiangular tight frames (ETFs) are configurations of vectors which are
optimally geometrically spread apart and provide resolutions of the identity.
Many known constructions of ETFs are group covariant, meaning they result from
the action of a group on a vector, like all known constructions of symmetric,
informationally complete, positive operator-valued measures. In this short
article, some results characterizing the transitivity of the symmetry groups of
ETFs will be presented as well as a proof that an infinite class of so-called
Gabor-Steiner ETFs are roux lines, where roux lines are a generalization of
doubly transitive lines.
|
http://arxiv.org/abs/1901.10612v2
|
1901.10612
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2019-05-21
|
computer-graphics
|
2 and 9 are the only biunitary superperfect numbers
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We shall show that 2 and 9 are the only biunitary superperfect numbers.
|
http://arxiv.org/abs/1705.00189v1
|
1705.00189
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2017-04-29
|
computer-graphics
|
2-Approximation for Prize-Collecting Steiner Forest
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Approximation algorithms for the prize-collecting Steiner forest problem (PCSF) have been a subject of research for over three decades, starting with the seminal works of Agrawal, Klein, and Ravi and Goemans and Williamson on Steiner forest and prize-collecting problems. In this paper, we propose and analyze a natural deterministic algorithm for PCSF that achieves a $2$-approximate solution in polynomial time. This represents a significant improvement compared to the previously best known algorithm with a $2.54$-approximation factor developed by Hajiaghayi and Jain in 2006. Furthermore, K{\"{o}}nemann, Olver, Pashkovich, Ravi, Swamy, and Vygen have established an integrality gap of at least $9/4$ for the natural LP relaxation for PCSF. However, we surpass this gap through the utilization of a combinatorial algorithm and a novel analysis technique. Since $2$ is the best known approximation guarantee for Steiner forest problem, which is a special case of PCSF, our result matches this factor and closes the gap between the Steiner forest problem and its generalized version, PCSF.
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https://arxiv.org/abs/2309.05172v2
|
2309.05172
|
2023-09-11
|
computer-graphics
|
2-Arc-transitive Cayley graphs on alternating groups
|
An interesting fact is that most of the known connected $2$-arc-transitive nonnormal Cayley graphs of small valency on finite simple groups are $(\mathrm{A}_{n+1},2)$-arc-transitive Cayley graphs on $\mathrm{A}_n$. This motivates the study of $2$-arc-transitive Cayley graphs on $\mathrm{A}_n$ for arbitrary valency. In this paper, we characterize the automorphism groups of such graphs. In particular, we show that for a non-complete $(G,2)$-arc-transitive Cayley graph on $\mathrm{A}_n$ with $G$ almost simple, the socle of $G$ is either $\mathrm{A}_{n+1}$ or $\mathrm{A}_{n+2}$. We also construct the first infinite family of $(\mathrm{A}_{n+2},2)$-arc-transitive Cayley graphs on $\mathrm{A}_n$.
|
https://arxiv.org/abs/2103.14784v1
|
2103.14784
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2021-03-27
|
computer-graphics
|
2-associahedra
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For any $r\geq 1$ and $\mathbf{n} \in \mathbb{Z}_{\geq0}^r \setminus
\{\mathbf0\}$ we construct a poset $W_{\mathbf{n}}$ called a 2-associahedron.
The 2-associahedra arose in symplectic geometry, where they are expected to
control maps between Fukaya categories of different symplectic manifolds. We
prove that the completion $\widehat{W_{\mathbf{n}}}$ is an abstract polytope of
dimension $|\mathbf{n}|+r-3$. There are forgetful maps $W_{\mathbf{n}} \to
K_r$, where $K_r$ is the $(r-2)$-dimensional associahedron, and the
2-associahedra specialize to the associahedra (in two ways) and to the
multiplihedra. In an appendix, we work out the 2- and 3-dimensional
associahedra in detail.
|
http://arxiv.org/abs/1709.00119v2
|
1709.00119
|
2018-08-22
|
computer-graphics
|
$(2B, 3A, 5A)$-subalgebras of the Griess algebra with alternating Miyamoto group
|
We use Majorana representations to study the subalgebras of the Griess algebra that have shape $(2B,3A,5A)$ and whose associated Miyamoto groups are isomorphic to $A_n$. We prove that these subalgebras exist only if $n\in \{5,6,8\}$. The case $n=5$ was already treated by Ivanov, Seress, McInroy, and Shpectorov. In case $n=6$ we prove that these algebras are all isomorphic and provide their precise description. In case $n=8$ we prove that these algebras do not arise from standard Majorana representations.
|
https://arxiv.org/abs/2504.17446v1
|
2504.17446
|
2025-04-24
|
computer-graphics
|
2^B3^C: 2 Box 3 Crop of Facial Image for Gender Classification with Convolutional Networks
|
In this paper, we tackle the classification of gender in facial images with
deep learning. Our convolutional neural networks (CNN) use the VGG-16
architecture [1] and are pretrained on ImageNet for image classification. Our
proposed method (2^B3^C) first detects the face in the facial image, increases
the margin of a detected face by 50%, cropping the face with two boxes three
crop schemes (Left, Middle, and Right crop) and extracts the CNN predictions on
the cropped schemes. The CNNs of our method is fine-tuned on the Adience and
LFW with gender annotations. We show the effectiveness of our method by
achieving 90.8% classification on Adience and achieving competitive 95.3%
classification accuracy on LFW dataset. In addition, to check the true ability
of our method, our gender classification system has a frame rate of 7-10 fps
(frames per seconds) on a GPU considering real-time scenarios.
|
http://arxiv.org/abs/1803.02181v1
|
1803.02181
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2018-03-05
|
computer-graphics
|
2-balanced sequences coding rectangle exchange transformation
|
We define a new class of ternary sequences that are 2-balanced. These sequences are obtained by colouring of Sturmian sequences. We show that the class contains sequences of any given letter frequencies. We provide an upper bound on factor and abelian complexity of these sequences. Using the interpretation by rectangle exchange transformation, we prove that for almost all triples of letter frequencies, the upper bound on factor and abelian complexity is reached. The bound on factor complexity is given using a number-theoretical function which we compute explicitly for a class of parameters.
|
https://arxiv.org/abs/2403.12791v1
|
2403.12791
|
2024-03-19
|
computer-graphics
|
2-bit Conformer quantization for automatic speech recognition
|
Large speech models are rapidly gaining traction in research community. As a result, model compression has become an important topic, so that these models can fit in memory and be served with reduced cost. Practical approaches for compressing automatic speech recognition (ASR) model use int8 or int4 weight quantization. In this study, we propose to develop 2-bit ASR models. We explore the impact of symmetric and asymmetric quantization combined with sub-channel quantization and clipping on both LibriSpeech dataset and large-scale training data. We obtain a lossless 2-bit Conformer model with 32% model size reduction when compared to state of the art 4-bit Conformer model for LibriSpeech. With the large-scale training data, we obtain a 2-bit Conformer model with over 40% model size reduction against the 4-bit version at the cost of 17% relative word error rate degradation
|
https://arxiv.org/abs/2305.16619v1
|
2305.16619
|
2023-05-26
|
computer-graphics
|
2-bit Model Compression of Deep Convolutional Neural Network on ASIC Engine for Image Retrieval
|
Image retrieval utilizes image descriptors to retrieve the most similar images to a given query image. Convolutional neural network (CNN) is becoming the dominant approach to extract image descriptors for image retrieval. For low-power hardware implementation of image retrieval, the drawback of CNN-based feature descriptor is that it requires hundreds of megabytes of storage. To address this problem, this paper applies deep model quantization and compression to CNN in ASIC chip for image retrieval. It is demonstrated that the CNN-based features descriptor can be extracted using as few as 2-bit weights quantization to deliver a similar performance as floating-point model for image retrieval. In addition, to implement CNN in ASIC, especially for large scale images, the limited buffer size of chips should be considered. To retrieve large scale images, we propose an improved pooling strategy, region nested invariance pooling (RNIP), which uses cropped sub-images for CNN. Testing results on chip show that integrating RNIP with the proposed 2-bit CNN model compression approach is capable of retrieving large scale images.
|
https://arxiv.org/abs/1905.03362v1
|
1905.03362
|
2019-05-08
|
computer-graphics
|
2-Bit Random Projections, NonLinear Estimators, and Approximate Near Neighbor Search
|
The method of random projections has become a standard tool for machine
learning, data mining, and search with massive data at Web scale. The effective
use of random projections requires efficient coding schemes for quantizing
(real-valued) projected data into integers. In this paper, we focus on a simple
2-bit coding scheme. In particular, we develop accurate nonlinear estimators of
data similarity based on the 2-bit strategy. This work will have important
practical applications. For example, in the task of near neighbor search, a
crucial step (often called re-ranking) is to compute or estimate data
similarities once a set of candidate data points have been identified by hash
table techniques. This re-ranking step can take advantage of the proposed
coding scheme and estimator.
As a related task, in this paper, we also study a simple uniform quantization
scheme for the purpose of building hash tables with projected data. Our
analysis shows that typically only a small number of bits are needed. For
example, when the target similarity level is high, 2 or 3 bits might be
sufficient. When the target similarity level is not so high, it is preferable
to use only 1 or 2 bits. Therefore, a 2-bit scheme appears to be overall a good
choice for the task of sublinear time approximate near neighbor search via hash
tables.
Combining these results, we conclude that 2-bit random projections should be
recommended for approximate near neighbor search and similarity estimation.
Extensive experimental results are provided.
|
http://arxiv.org/abs/1602.06577v1
|
1602.06577
|
2016-02-21
|
computer-graphics
|
2-bit topological-encoded acoustic multifunctional device
|
Valley degree of freedom, an excellent information carrier in valleytronics, has been further introduced into advanced microstructure systems for achieving the acoustic valley-Hall topological insulators (VHTIs), which host valley-projected edge states suppressing the undesired sound backscattering under certain perturbations. Therein, the majority of previous literatures focused on single frequency region, and the lack of capability of simultaneous multi-band operation with individual control radically impedes their potential applications. Here, a binary topological-encoded acoustic VHTI is investigated both theoretically and experimentally to manipulate each of the dual-band valley-projected edge states. Through arranging different coding elements derived from the combined valley-Chern numbers, the existence and propagation directions of the frequency selective edge states can be configured in corresponding frequency regions individually. On this basis, three types of proof-of-concept acoustic topological-encoded functional devices are designed, including frequency beam splitter, anti-interference demultiplex topological sensing and composite topological whispering gallery. Our proposal may provide versatile possibilities for achieving the integrated multifunctional systems in multi-channel signal processing and memorizing with high efficiency and high capacity.
|
https://arxiv.org/abs/2104.10607v3
|
2104.10607
|
2021-04-21
|
computer-graphics
|
2BiVQA: Double Bi-LSTM based Video Quality Assessment of UGC Videos
|
Recently, with the growing popularity of mobile devices as well as video sharing platforms (e.g., YouTube, Facebook, TikTok, and Twitch), User-Generated Content (UGC) videos have become increasingly common and now account for a large portion of multimedia traffic on the internet. Unlike professionally generated videos produced by filmmakers and videographers, typically, UGC videos contain multiple authentic distortions, generally introduced during capture and processing by naive users. Quality prediction of UGC videos is of paramount importance to optimize and monitor their processing in hosting platforms, such as their coding, transcoding, and streaming. However, blind quality prediction of UGC is quite challenging because the degradations of UGC videos are unknown and very diverse, in addition to the unavailability of pristine reference. Therefore, in this paper, we propose an accurate and efficient Blind Video Quality Assessment (BVQA) model for UGC videos, which we name 2BiVQA for double Bi-LSTM Video Quality Assessment. 2BiVQA metric consists of three main blocks, including a pre-trained Convolutional Neural Network (CNN) to extract discriminative features from image patches, which are then fed into two Recurrent Neural Networks (RNNs) for spatial and temporal pooling. Specifically, we use two Bi-directional Long Short Term Memory (Bi-LSTM) networks, the first is used to capture short-range dependencies between image patches, while the second allows capturing longrange dependencies between frames to account for the temporal memory effect. Experimental results on recent large-scale UGC VQA datasets show that 2BiVQA achieves high performance at lower computational cost than most state-of-the-art VQA models. The source code of our 2BiVQA metric is made publicly available at: https://github.com/atelili/2BiVQA
|
https://arxiv.org/abs/2208.14774v3
|
2208.14774
|
2022-08-31
|
computer-graphics
|
$2$-blocks in strongly biconnected directed graphs
|
A directed graph $G=(V,E)$ is called strongly biconnected if $G$ is strongly
connected and the underlying graph of $G$ is biconnected. A strongly
biconnected component of a strongly connected graph $G=(V,E)$ is a maximal
vertex subset $L\subseteq V$ such that the induced subgraph on $L$ is strongly
biconnected. Let $G=(V,E)$ be a strongly biconnected directed graph. A
$2$-edge-biconnected block in $G$ is a maximal vertex subset $U\subseteq V$
such that for any two distict vertices $v,w \in U$ and for each edge $b\in E$,
the vertices $v,w$ are in the same strongly biconnected components of
$G\setminus\left\lbrace b\right\rbrace $. A $2$-strong-biconnected block in $G$
is a maximal vertex subset $U\subseteq V$ of size at least $2$ such that for
every pair of distinct vertices $v,w\in U$ and for every vertex $z\in
V\setminus\left\lbrace v,w \right\rbrace $, the vertices $v$ and $w$ are in the
same strongly biconnected component of $G\setminus \left\lbrace v,w
\right\rbrace $. In this paper we study $2$-edge-biconnected blocks and
$2$-strong biconnected blocks.
|
http://arxiv.org/abs/2007.09793v1
|
2007.09793
|
2020-07-19
|
computer-graphics
|
2-blocks with an abelian defect group and a freely acting cyclic inertial quotient
|
We study blocks with an abelian defect group and a cyclic inertial quotient
acting freely but not transitively. We prove that when p=2, such blocks are
inertial, i.e. basic Morita equivalent to their Brauer correspondent. Together
with a result of the second author on Singer cycle actions on homocyclic defect
groups, this completes the classification of 2-blocks with a cyclic inertial
quotient acting freely on an abelian defect group.
|
http://arxiv.org/abs/2010.08329v2
|
2010.08329
|
2020-10-19
|
computer-graphics
|
2B or not 2B, a study of bottom-quark-philic semi-visible jets
|
Semi-visible jets arise in strongly interacting dark sector, resulting in jets overlapping with the missing transverse momentum direction. The implementation of semi-visible jets is done using the Pythia Hidden Valley module to mimic the QCD sector showering in so-called dark shower. In this work, only heavy flavour Standard Model quarks are considered in dark shower, resulting in a much less ambiguous collider signature of semi-visible jets compared to the democratic production of all five quark flavours in dark shower. The constraints from available searches on this signature are presented, and it is shown the signal reconstruction can be improved by using variable-radius jets. Finally a search strategy is suggested.
|
https://arxiv.org/abs/2207.01885v4
|
2207.01885
|
2022-07-05
|
computer-graphics
|
2$b$ or not 2$b$: on the rejection of $g\to b\bar b$ jets
|
Motivated by new physics models which lead to final states containing a high multiplicity of bottom and top quarks, we develop a tagging strategy to suppress reducible and non-reducible multi-jet backgrounds. The idea takes advantage of the properties of light parton showers and of the gluon fragmentation into heavy quarks to reject jets that do not originate from a bottom quark.
|
https://arxiv.org/abs/2310.04380v2
|
2310.04380
|
2023-10-06
|
computer-graphics
|
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