Sub-Band Knowledge Distillation Framework for Speech Enhancement

In single-channel speech enhancement, methods based on full-band spectral features have been widely studied. However, only a few methods pay attention to non-full-band spectral features. In this paper, we explore a knowledge distillation framework based on sub-band spectral mapping for single-channel speech enhancement. Specifically, we divide the full frequency band into multiple sub-bands and pre-train an elite-level sub-band enhancement model (teacher model) for each sub-band. These teacher models are dedicated to processing their own sub-bands. Next, under the teacher models' guidance, we train a general sub-band enhancement model (student model) that works for all sub-bands. Without increasing the number of model parameters and computational complexity, the student model's performance is further improved. To evaluate our proposed method, we conducted a large number of experiments on an open-source data set. The final experimental results show that the guidance from the elite-level teacher models dramatically improves the student model's performance, which exceeds the full-band model by employing fewer parameters.Comment: Published in Interspeech 202

Isolation and characterization of human spermatogonial stem cells

<p>Abstract</p> <p>Background</p> <p>To isolate and characterization of human spermatogonial stem cells from stem spermatogonium.</p> <p>Methods</p> <p>The disassociation of spermatogonial stem cells (SSCs) were performed using enzymatic digestion of type I collagenase and trypsin. The SSCs were isolated by using Percoll density gradient centrifugation, followed by differential surface-attachment method. Octamer-4(OCT4)-positive SSC cells were further identified using immunofluorescence staining and flow cytometry technques. The purity of the human SSCs was also determined, and a co-culture system for SSCs and Sertoli cells was established.</p> <p>Results</p> <p>The cell viability was 91.07% for the suspension of human spermatogonial stem cells dissociated using a two-step enzymatic digestion process. The cells isolated from Percoll density gradient coupled with differential surface-attachement purification were OCT4 positive, indicating the cells were human spermatogonial stem cells. The purity of isolated human spermatogonial stem cells was 86.7% as assessed by flow cytometry. The isolated SSCs were shown to form stable human spermatogonial stem cell colonies on the feeder layer of the Sertoli cells.</p> <p>Conclusions</p> <p>The two-step enzyme digestion (by type I collagenase and trypsin) process is an economical, simple and reproducible technique for isolating human spermatogonial stem cells. With little contamination and less cell damage, this method facilitates isolated human spermatogonial stem cells to form a stable cell colony on the supporting cell layer.</p

Direct visualization of iron sheath shielding effect in MgB_2 superconducting wires

Local magneto-optical imaging and global magnetization measurement techniques were used in order to visualize shielding effects in the superconducting core of MgB_2 wires sheathed by ferromagnetic iron (Fe). The magnetic shielding can provide a Meissner-like state in the superconducting core in applied magnetic fields up to ~1T. The maximum shielding fields are shown to correlate with the saturation fields of magnetization in Fe-sheaths. The shielding has been found to facilitate the appearance of an overcritical state, which is capable of achieving a critical current density (J_c) in the core which is larger than J_c in the same wire without the sheath by a factor of ~2. Other effects caused by the magnetic interaction between the sheath and the superconducting core are discussed.Comment: 4 pages, 3 figure

Direct visualization of iron sheath shielding effects in MgB 2 superconducting wires

Abstract Local magneto-optical imaging and global magnetization measurement techniques were used in order to visualize shielding effects in the superconducting core of MgB 2 wires sheathed by ferromagnetic iron (Fe). The magnetic shielding can provide a Meissner-like state in the superconducting core in applied magnetic fields up to ∼1 T. The maximum shielding fields are shown to correlate with the saturation fields of magnetization in Fe-sheaths. The shielding has been found to facilitate the appearance of an overcritical state, which is capable of achieving a critical current density (J c ) in the core which is larger than J c in the same wire without the sheath by a factor of ∼2. Other effects caused by the magnetic interaction between the sheath and the superconducting core are discussed. New promising horizons for applications of superconducting wires were opened up by the discovery of the MgB 2 superconductor [1]. MgB 2 wires have been reported to have high values of the critical current density J c , in particular in wires sheathed by mechanically hard and magnetically soft materials such as iron (Fe) Fe-sheathed MgB 2 mono-core (MC) and multifilamentary (MF) superconducting wires were investigated. A detailed description of the wire manufacturing procedure and its characterization is given elsewher

Properties of superconducting MgB_2 wires: "in-situ" versus "ex-situ" reaction technique

We have fabricated a series of iron-sheathed superconducting wires prepared by the powder-in-tube technique from (MgB_2)_{1-x}:(Mg+2B)_x initial powder mixtures taken with different proportions, so that x varies from 0 to 1. It turned out that "ex-situ" prepared wire (x = 0) has considerable disadvantages compared to all the other wires in which "in-situ" assisted (0 < x < 1) or pure "in-situ" (x = 1) preparation was used due to weaker inter-grain connectivity. As a result, higher critical current densities J_c were measured over the entire range of applied magnetic fields B_a for all the samples with x > 0. Pinning of vortices in MgB_2 wires is shown to be due to grain boundaries. J_c(B_a) behavior is governed by an interplay between the transparency of grain boundaries and the amount of "pinning" grain boundaries. Differences between thermo-magnetic flux-jump instabilities in the samples and a possible threat to practical applications are also discussed.Comment: To be published in Supercond. Sci. Technol. (2003), in pres

Cell-Free DNA Sequencing of Intraocular Fluid as Liquid Biopsy in the Diagnosis of Vitreoretinal Lymphoma

PurposeTo seek novel diagnostic approaches, we improved the workflow of cell-free DNA (cfDNA) sequencing and evaluated its feasibility in vitreoretinal lymphoma (VRL) specimens; the profile of mutations was preliminarily analyzed for potential diagnostic value.MethodsThe study was a diagnostic trial. 23 eyes of 23 patients with VRL and 25 eyes of 25 patients with inflammatory eye diseases were enrolled. Approximate 500μl undiluted vitreous humor and 10ml diluted vitreous fluid was obtained through diagnostic vitrectomy and sent for cytopathological examinations. 500μl of the diluted vitreous fluid was spared for cfDNA sequencing. For cfDNA sequencing, DNA fragmentation procedure was added to the workflow to improve the extraction efficiency; mutations detected were analyzed for potential diagnostic model. The sensitivity and specificity of the cytopathology and cfDNA sequencing were compared. The clinical manifestations were preliminarily analyzed for potential correlations with the genotypes.ResultsCfDNA sequencing was accomplished in 23 eyes with VRL and 20 eyes with inflammatory eye diseases. VRL-related mutated genes included MYD88 (18 eyes, 78%), ETV6 (11 eyes, 48%), PIM1 (11 eyes,48%), BTG2 (7 eyes, 30%), IRF4 (7 eyes, 30%), CD79B (6 eyes, 26%), LRP1B (6 eyes, 26%), etc. Logistic regression based on the mutations of MYD88 and ETV6 was of the potential for the diagnosis of VRL (P&lt;0.001, adjusted R2 = 0.789, sensitivity 0.913, specificity 0.950); by comparison, the sensitivity and specificity of the vitreous cytopathology were 0.826 and 1.000, respectively. Further analysis of the mutation profile showed that patients carrying CD79B mutation tended to have higher intraocular interleukin-10 level (P=0.030), that CARD11 mutation was correlated with younger age at ocular onset (P=0.039), and that patients with intracranial involvement carried more multiple-site mutations in the BTG2 gene (P=0.013).ConclusionsThe improved workflow of CfDNA sequencing is of sound feasibility in a limited amount of vitreous humor. The logistic model based on the mutations could help to provide reliable clues for the diagnosis of VRL

The relationships of preventive behaviors and psychological resilience with depression, anxiety, and stress among university students during the COVID-19 pandemic: A two-wave longitudinal study in Shandong Province, China

IntroductionStudies have shown that the psychological impact of the COVID-19 pandemic may lead to long-term health problems; therefore, more attention should be paid to the mental health of university students. This study aimed to explore the longitudinal effects of preventive behaviors and psychological resilience on the mental health of Chinese college students during COVID-19.MethodsWe recruited 2,948 university students from five universities in Shandong Province. We used a generalized estimating equation (GEE) model to estimate the impact of preventive behaviors and psychological resilience on mental health.ResultsIn the follow-up survey, the prevalence of anxiety (44.8% at T1 vs 41.2% at T2) and stress (23.0% at T1 vs 19.6% at T2) decreased over time, whereas the prevalence of depression (35.2% at T1 vs 36.9% at T2) increased significantly (P &lt; 0.001). Senior students were more likely to report depression (OR = 1.710, P &lt; 0.001), anxiety (OR = 0.815, P = 0.019), and stress (OR = 1.385, P = 0.011). Among all majors, medical students were most likely to report depression (OR = 1.373, P = 0.021), anxiety (OR = 1.310, P = 0.040), and stress (OR = 1.775, P &lt; 0.001). Students who wore a mask outside were less likely to report depression (OR = 0.761, P = 0.027) and anxiety (OR = 0.686, P = 0.002) compared to those who did not wear masks. Students who complied with the standard hand-washing technique were less likely to report depression (OR = 0.628, P &lt; 0.001), anxiety (OR = 0.701, P &lt; 0.001), and stress (OR = 0.638, P &lt; 0.001). Students who maintained a distance of one meter in queues were less likely to report depression (OR = 0.668, P &lt; 0.001), anxiety (OR = 0.634, P &lt; 0.001), and stress (OR = 0.638, P &lt; 0.001). Psychological resilience was a protective factor against depression (OR = 0.973, P &lt; 0.001), anxiety (OR = 0.980, P &lt; 0.001), and stress (OR = 0.976, P &lt; 0.001).DiscussionThe prevalence of depression among university students increased at follow-up, while the prevalence of anxiety and stress decreased. Senior students and medical students are vulnerable groups. University students should continue to follow relevant preventive behaviors to protect their mental health. Improving psychological resilience may help maintain and promote university students' mental health