Low Frequency
Recently Published Documents


(FIVE YEARS 13074)



2021 ◽  
Vol 8 (1) ◽  
pp. 105-118
Yakun Ju ◽  
Yuxin Peng ◽  
Muwei Jian ◽  
Feng Gao ◽  
Junyu Dong

AbstractPhotometric stereo aims to reconstruct 3D geometry by recovering the dense surface orientation of a 3D object from multiple images under differing illumination. Traditional methods normally adopt simplified reflectance models to make the surface orientation computable. However, the real reflectances of surfaces greatly limit applicability of such methods to real-world objects. While deep neural networks have been employed to handle non-Lambertian surfaces, these methods are subject to blurring and errors, especially in high-frequency regions (such as crinkles and edges), caused by spectral bias: neural networks favor low-frequency representations so exhibit a bias towards smooth functions. In this paper, therefore, we propose a self-learning conditional network with multi-scale features for photometric stereo, avoiding blurred reconstruction in such regions. Our explorations include: (i) a multi-scale feature fusion architecture, which keeps high-resolution representations and deep feature extraction, simultaneously, and (ii) an improved gradient-motivated conditionally parameterized convolution (GM-CondConv) in our photometric stereo network, with different combinations of convolution kernels for varying surfaces. Extensive experiments on public benchmark datasets show that our calibrated photometric stereo method outperforms the state-of-the-art.

2021 ◽  
pp. 135965352110422
Franco Maggiolo ◽  
Nicola Gianotti ◽  
Laura Comi ◽  
Elisa Di Filippo ◽  
Laura Fumagalli ◽  

Background Primary analysis at 24 weeks showed that switching to rilpivirine plus darunavir/cobicistat was non-inferior to continuing a standard three-drug antiretroviral regimen in virologically suppressed people with HIV. We present efficacy and safety data from the 48-week analysis. Methods PROBE 2 is a randomized, open-label trial. Adults who were on a three-drug therapy and had had <50 HIV-1 RNA copies/mL for at least 6 months were randomly assigned (1:1) to 25 mg rilpivirine plus 800/150 darunavir/cobicistat once daily (early switch group) or to continue their regimen for 24 weeks before switching (late switch group). In the 48-week analysis, the efficacy endpoint was the proportion of participants with <50 copies/mL of HIV-RNA (US Food and Drug Administration snapshot algorithm). The trial is registered with ClinicalTrials.gov , number NCT04064632. Findings 160 participants were recruited and randomized. At week 48, 70 (87.5%) in the early switch group and 76 (94.8%) in the late switch group maintained HIV-RNA <50 copies/mL. Virological failure (≥50 HIV-RNA copies/mL) was not seen in any patient of the early switch group and in 2 subjects in the late switch group none of which had treatment emergent resistance-associated mutation. Adverse events leading to treatment discontinuation occurred in 7 (8.7%) participants in the early switch group and in none in the late switch group. Interpretation The combination of rilpivirine plus darunavir/cobicistat sustained virological suppression, was associated with a low frequency of virological failure, and had a favorable safety profile, which support its use as a nucleoside reverse transcriptase inhibitor-sparing and integrase inhibitor-sparing alternative to three-drug regimens.

2021 ◽  
pp. 58-1
Antoine Hochet ◽  
Thierry Huck ◽  
Olivier Arzel ◽  
Florian Sévellec ◽  
Alain Colin de Verdiére

AbstractOne of the proposed mechanisms to explain the multidecadal variability observed in sea surface temperature of the North Atlantic consists of a large-scale low-frequency internal mode spontaneously developing because of the large-scale baroclinic instability of the time-mean circulation. Even though this mode has been extensively studied in terms of the buoyancy variance budget, its energetic properties remain poorly known. Here we perform the full mechanical energy budget including available potential energy (APE) and kinetic energy (KE) of this internal mode and decompose the budget into three frequency bands: mean, low frequency (LF) associated with the large-scale mode and high frequency (HF) associated with mesocale eddy turbulence. This decomposition allows us to diagnose the energy fluxes between the different reservoirs and to understand the sources and sinks. Due to the large-scale of the mode, most of its energy is contained in the APE. In our configuration, the only source of LF APE is the transfer from mean APE to LF APE that is attributed to the large-scale baroclinic instability. In return the sinks of LF APE are the parameterized diffusion, the flux toward HF APE and to a much lesser extent toward LF KE. The presence of an additional wind-stress component weakens multidecadal oscillations and modifies the energy fluxes between the different energy reservoirs. The KE transfer appears to only have a minor influence on the multidecadal mode compared to the other energy sources involving APE, in all experiments. These results highlight the utility of the full APE/ KE budget.

Kai R. Caspar ◽  
Alexandra Heinrich ◽  
Lea Mellinghaus ◽  
Patricia Gerhardt ◽  
Sabine Begall

Hearing in subterranean rodents exhibits numerous peculiarities, including low sensitivity and restriction to a narrow range of comparatively low frequencies. Past studies provided two conflicting hypotheses explaining how these derived traits evolved: structural degeneration and adaptive specialization. To further elucidate this issue, we recorded auditory brainstem responses from three species of social subterranean rodents that differ in the degree of specialization to the underground habitat: The naked mole-rat (Heterocephalus glaber) and the Mashona mole-rat (Fukomys darlingi) which represent the ancient lineage of African mole-rats (Bathyergidae) and the coruro (Spalacopus cyanus), a South American rodent (Octodontidae) which adopted a subterranean lifestyle in more recent geological time. Additionally, we measured call amplitudes of social vocalizations to study auditory vocal coupling. We found elevated auditory thresholds and severe low-frequency hearing range restrictions in the African mole-rats, with hearing in naked mole-rats tending to be more sensitive than in Mashona mole-rats. In contrast to that, hearing in coruros was similar to that of epigeic rodents, with its range extending into ultrasonic frequencies. However, as in the mole-rats, the coruros’ region of best hearing was located at low frequencies close to 1 kHz. We argue that the auditory sensitivity of African mole-rats, although remarkably poor, has been underestimated by recent studies, while data on coruros conform to previous results. Considering the available evidence, we propose to be open to both degenerative and adaptive interpretations of hearing physiology in subterranean mammals, as each may provide convincing explanations for specific auditory traits observed.

2021 ◽  
Vol 15 ◽  
Sishi Liu ◽  
Xianglong Wang ◽  
Junqin Ma ◽  
Kangling Wang ◽  
Zhengtao Wang ◽  

Objective: Executive function refers to the conscious control of thinking and behavior in psychological process. Executive dysfunction widely exists in a variety of neuropsychiatric diseases, and is closely related to the decline of daily living ability and function. This study intends to explore the effect of low-frequency repetitive transcranial magnetic stimulation (rTMS) on executive function and its neural mechanism by using event-related potential (ERP), so as to provide basis for further study on the relationship between cerebral cortex and executive function.Methods: Task switching paradigm was used to study the cognitive flexibility in executive function. Thirty-one healthy subjects were randomly assigned to receive rTMS stimulations (1 Hz rTMS or sham rTMS) to the left dorsolateral prefrontal cortex (DLPFC) twice. The switching task and the electroencephalography EEG recordings were performed before (pre-rTMS/pre-sham rTMS) and immediately after the end of the rTMS application (post-rTMS/post-sham rTMS).Results: The analysis of RTs showed that the main effects of switching and time were statistically significant. Further analysis revealed that the RT of rTMS stimulation was longer than sham rTMS at post-stimulation. ERP analysis showed that there was a significant switching effect in frontal and central scalp location, and the P2 amplitude in switch trials was greater than that in non-switch trials. At post-stimulation, the N2 amplitude of rTMS is more negative than that of sham rTMS at non-switch trials, whereas no such difference was found at switch trials. The P3 amplitude and LPC amplitude are significantly reduced by rTMS at post-stimulation.Conclusion: Low-frequency rTMS of the left DLPFC can cause decline of cognitive flexibility in executive function, resulting in the change of N2 amplitude and the decrease of P3 and LPC components during task switching, which is of positive significance for the evaluation and treatment of executive function.

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Feifei Jiang ◽  
Wenting Yao

Graphic design is an important part of the design field today. In this era of information explosion, designs that can deliver information faster and more accurately are bound to gain popularity among the public. In this paper, we propose a fast decomposition algorithm image processing method based on a new transform of the wavelet transform, which mainly addresses the problems of large computation of feature points and long-time consumption of traditional image processing algorithms. Firstly, the second-order decomposition of the image is performed by wavelet function to obtain the low-frequency components of the image, and the wavelet gradient vector is used to extract feature points from the overlapping regions of the low-frequency image so that the transformation parameters of feature points can be obtained quickly under the low-frequency image to guide the feature point extraction under the high-frequency image; on this basis, an improved algorithm of image processing based on the fast decomposition algorithm of two-dimensional wavelet transform with planar design is proposed. Using the properties of one-way matching and directional consistency of feature point constraints, the mismatched point pairs are effectively eliminated to improve the feature point matching accuracy and real-time performance. Finally, the effectiveness and feasibility of the proposed method are verified by two sets of experiments.

2021 ◽  
Vol 73 (1) ◽  
Masayuki Kano ◽  
Aoi Ikeuchi ◽  
Takuya Nishimura ◽  
Shin’ichi Miyazaki ◽  
Takeshi Matsushima

AbstractThe southern part of the Ryukyu subduction zone has recorded tsunami events with a recurrence interval of several hundred years. Although their source is controversial, one model suggests that the last 1771 Yaeyama tsunami was caused by a shallow megathrust earthquake with a magnitude of 8. However, the current knowledge on interplate coupling based on recent geodetic data is limited. Here, a time series of Global Navigation Satellite System data from January 2010 to February 2021 was analyzed, including newly installed stations by Kyoto and Kyushu Universities, to obtain the distance changes between stations and vertical secular velocities. The distance changes ranged from 2.4 mm/year in contraction and to 4.7 mm/year in extension, and the vertical velocities exhibited no clear uplift or subsidence, with − 2.4 to 1.1 mm/year. The back slip inversion results indicated a slip deficit of 17–47 mm/year to the south of the Yaeyama Islands. The large slip deficit area is complementarily intervened between the shallower source area of low-frequency earthquakes and the deeper slow slip region, suggesting the spatial heterogeneity of frictional properties along the plate interface. If the large slip deficit area accumulates stress in the same rate since the last 1771 earthquake, it could result in a megathrust event with a moment magnitude greater than 7.5. Because the limited onshore data cannot resolve the slip deficit on the shallow plate interface, seafloor geodetic observations are essential to clarify the detailed spatial distribution of the slip deficit and discuss its earthquake and tsunami potential. Graphical Abstract

Sign in / Sign up

Export Citation Format

Share Document