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We report a kind of coiled-up meta-liners with nonuniform cross sections (CMNC), which can efficiently attenuate low-frequency sound waves under grazing flow with a deep subwavelength thickness (e.g., ∼λ/17 at 500 Hz). At a grazing flow Mach number of 0.26, the average transmission loss of the meta-liner is 12.6 dB at 500–1000 Hz, which is twice as much as that of a double-degree-of-freedom acoustic liner of the same size. Physically, the nonuniform cross-sectional distribution and significant cross-sectional area ratio enhances vortex shedding, thus resulting in severe acoustic energy dissipation. The excellent low-frequency acoustic attenuation performance of CMNC is investigated thoroughly with experimental, theoretical, and numerical methods. This work provides an avenue for low-frequency noise reduction in grazing flow scenarios (e.g., in a high bypass ratio turbofan engine). [ABSTRACT FROM AUTHOR]

Proposed here is a metastructure based on a micro-perforated panel and an impedance-matching coiled-up cavity with continuously variable cross section, which achieves perfect absorption with a resonant frequency of 496 Hz and an absolute bandwidth (α ≥ 0.5) of 468 Hz. The structure thickness is ca. 1/13 of the operating wavelength λ in the deep subwavelength range. A relative bandwidth of 84.04%–111.67% is achieved through parametric studies. Physically, the continuous variation of the cavity cross section through which sound waves enter weakens the acoustic reflections generated by cross-sectional abruptness and enhances the impedance matching with the air. Furthermore, particle swarm optimization is coupled with a theoretical model to tailor the metastructure to realize the maximum absorption coefficient in the defined frequency range. It is shown theoretically that coherent coupling "weak resonance"—in which each unit individually exhibits imperfect absorption peaks—significantly improves the absorption performance in a broad frequency band through the coherent coupling effect. Finally, a hybrid metastructure using a parallel coupling sample is fabricated, and its acoustic properties are measured in an impedance tube. The average absorption coefficient of this metastructure is 0.934 in the quasi-perfect band (α > 0.9) from 400 to 650 Hz, and the thickness is only ca. λ/15. The unique innovation of a cavity with continuously variable cross section provides new ideas for designing broadband low-frequency sound-absorbing metastructures. [ABSTRACT FROM AUTHOR]

The core of underwater acoustic recognition is to extract the spectral features of targets. The running speed and track of the targets usually result in a Doppler shift, which poses significant challenges for recognizing targets with different Doppler frequencies. This paper proposes deep learning with a channel attention mechanism approach for underwater acoustic recognition. It is based on three crucial designs. Feature structures can obtain high-dimensional underwater acoustic data. The feature extraction model is the most important. First, we develop a ResNet to extract the deep abstraction spectral features of the targets. Then, the channel attention mechanism is introduced in the camResNet to enhance the energy of stable spectral features of residual convolution. This is conducive to subtly represent the inherent characteristics of the targets. Moreover, a feature classification approach based on one-dimensional convolution is applied to recognize targets. We evaluate our approach on challenging data containing four kinds of underwater acoustic targets with different working conditions. Our experiments show that the proposed approach achieves the best recognition accuracy (98.2%) compared with the other approaches. Moreover, the proposed approach is better than the ResNet with a widely used channel attention mechanism for data with different working conditions. [ABSTRACT FROM AUTHOR]

• IMDCC consisting of a micro-perforated plate and a porous material. • IMDCC demonstrate marvelous broadband sound absorption, there are three significant absorption peaks in the uncoupled unit. • The feasibility of the bandwidth mechanism is verified for different parameters. • Good agreements are achieved between the theoretical, numerical and experimental results. This work presents an impedance-matching double nesting channel composite metastructure consisting of a micro-perforated plate and a porous material (IMDCC). Combining the acoustic properties of the porous material and the nesting channels, a plane wave expansion method is used to establish a theoretical model for studying the sound absorption of IMDCC. Finite element simulations are used to verify the validity of the theoretical model. The proposed absorber with IMDCC shows excellent subwavelength low-frequency ultra-broadband sound absorption capabilities based on nesting channel, reaching perfect absorption at 625 Hz with an absolute bandwidth of 1090 Hz and a thickness of only 1/12.19 of the corresponding wavelength without considering multi-unit coupling. The energy transmission and dissipation reveal frequency-dependent acoustic transmission path properties. Furthermore, different structural and transmission parameters reveal ultra-broadband acoustic absorption properties. Experiments verify that the IMDCC absorber provides multiple-resonance sound absorption and ultra-broadband sound absorption with an absolute bandwidth of 1330 Hz. This work should be useful for the design of new subwavelength low-frequency acoustic absorbing metastructures. [ABSTRACT FROM AUTHOR]

In order to study the effect of different joint types on the core noise of transformer, this article proposes a method based on the equivalent magnetostriction properties of the core joints. First, the 2-D magnetic field simulation of the core model with joints is performed to obtain the flux density distribution, by which the equivalent magnetization and magnetostriction characteristics of the joint are calculated. Then, core joints are defined by a new material with equivalent properties to simulate the magnetic field of the 3-D core models, and the magnetic-force–acoustic coupling analysis is performed by the finite element method to calculate the noise of the models. Finally, the effectiveness of the calculation method is verified by noise test. The results show that the simulation is consistent with the test. This article provides a new method for improving the accuracy of transformer core noise prediction further. [ABSTRACT FROM AUTHOR]

In this paper, the two-zone sound field reproduction problem is investigated with a newly proposed method. The aim of the two-zone reproduction problem is to achieve sound field reproduction in the bright zone while keeping the sound field energy in the dark zone as low as possible. The main difference between the proposed method and the conventional method is that the sound field control in the dark zone is not limited to a small number of measurement points on the region boundary but to measurement points throughout the whole dark zone. For practical reasons, the whole region is discretized into a grid, and the grid selection method is also provided in this paper. Simulations are performed to compare the performances of the proposed and conventional methods with different virtual source directions, and a comparison of the robustness to the regularization parameter shows that the proposed method is less sensitive to the selection of the regularization parameter. Finally, an experiment is performed with a circular loudspeaker array in a real listening room. A quieter dark zone is achieved by the proposed method while keeping the reproduction error in the bright zone close to that of the conventional method, similar to the simulation results. These outcomes verify that the proposed method performs well in both free-field and reverberation environments. [ABSTRACT FROM AUTHOR]

Personalization of head-related transfer functions (HRTFs) is an essential task in the research on virtual hearing. In this paper, a method based on sparse principal component analysis (SPCA) and sparse representation (SR) was proposed to personalize HRTFs. The fundamental assumption is that an equivalent sparse combination can express the same anthropometric parameters. SPCA was first used to reduce the dimensionality of three-dimensional anthropometric parameters, and the reduced physiological parameters were used to reconstruct a physiological parameter database. SR was performed on the reconstructed physiological parameters of all subjects. For each subject, SR was used on the anthropometric parameters that were consistent with those in the reconstruction database. The matching pursuit algorithm was used to obtain the subjects in the database that had the same SR as the subject, and the HRTFs of the matched subject were used as the HRTFs of the new subject. The effect of the proposed method was evaluated by spectral distortion. The results showed that the method did better than others regardless of whether the Chinese pilots' database or the CIPIC database was used, especially in the 0–8 kHz bandwidth. [ABSTRACT FROM AUTHOR]

In marine economics and military activities, the timely recognition of underwater acoustic targets in complex environments is particularly important. The conditions of ship navigation can greatly affect the radiation noise. However, due to the difficulties of marine experiments, the collected data only contains a limited part of the working conditions, which makes underwater acoustic target recognition difficult. To solve the problem of working conditions mismatching, we proposed a deep neural network based on knowledge distillation. In the proposed method, the teacher network uses sufficient straight working condition data to obtain prior knowledge. Then, while training with a small amount of target working data, the student network patiently learns the classification knowledge from the feature-based knowledge and the response-based knowledge of the teacher network by using the knowledge distillation method to extract incremental knowledge. Knowledge distillation is used to improve the accuracy of the classification of target working condition data by student network. The effectiveness of the method was verified on multi-working conditions ship-radiated noise datasets. The experimental results show that the proposed method can improve the performance of underwater acoustic target recognition under working conditions mismatching. [ABSTRACT FROM AUTHOR]

Wave-based methods for acoustic simulations within enclosures suffer the numerical dispersion and then usually have evident dispersion error for problems with high wave numbers. To improve the upper limit of calculating frequency for 3D problems, a hybrid smoothed finite element method (hybrid SFEM) is proposed in this paper. This method employs the smoothing technique to realize the reduction of the numerical dispersion. By constructing a type of mixed smoothing domain, the traditional node-based and face-based smoothing techniques are mixed in the hybrid SFEM to give a more accurate stiffness matrix, which is widely believed to be the ultimate cause for the numerical dispersion error. The numerical examples demonstrate that the hybrid SFEM has better accuracy than the standard FEM and traditional smoothed FEMs under the condition of the same basic elements. Moreover, the hybrid SFEM also has good performance on the computational efficiency. A convergence experiment shows that it costs less time than other comparison methods to achieve the same computational accuracy. [ABSTRACT FROM AUTHOR]

Uncertain speed of sound will lead that the interval perturbation method fails to precisely predict the uncertain acoustic field in some frequency bands. An uncertainty reduction technique is proposed for this problem. This technique first determines the bands in which the interval method is being invalid through the modal frequency analysis. Then, the dimensionality of the uncertain parameters is reduced by converting the uncertain speed of sound into a certain one. This technique can be used in the interval or subinterval perturbation methods. The numerical example demonstrates that the proposed technique is effective for uncertain acoustic field simulation with interval parameters. [ABSTRACT FROM AUTHOR]

Highlights: [•] Bark-wavelet analysis is used for the denoising. [•] Hilbert–Huang transform is used on feature extraction. [•] Classification experiments under different SNRs are used for the evaluation. [•] Presented algorithm has better performances than the baseline system under low SNRs. [Copyright &y& Elsevier]

Abstract: The details are provided for the derivation and implementation of a meshless model based on the Element-free Galerkin Method for calculating sound fields. The model is applicable to three-dimensional small enclosures with arbitrary shape. In the model, the system equation for calculating the sound pressure of nodes is derived using the Galerkin weighted residual method. The shape functions are constructed using the moving least squares method, and the methods for calculating the integrals are described in detail. The frequency response function of a rectangular enclosure and a cylindrical enclosure are calculated using the model, and the results are compared with the results obtained using a theoretical method, Boundary Element Method (BEM), and with experimental results, respectively. Next, the factors that influence the performance of the method, which include the distribution and number of nodes, the number of integration points, the types of basis, and the weight functions, are discussed. The suitable support domain radius for the calculation of sound fields in small enclosures is also obtained through use of numerical experiments. Finally, the meshless model with suitable parameters is used to calculate the sound field of an airplane cabin. Comparison of the calculated sound pressure levels with the measured results has validated the model’s accuracy and applicability to enclosures with complicated structures. [Copyright &y& Elsevier]

Abstract: To predict acoustics of rooms using computer programs based on geometrical assumptions, it is important that scattering is included in the calculations. Therefore scattering is usually included in terms of scattering coefficients which are assigned to each surface telling the software the ratio between the part of the reflected energy which is not being reflected specularily and the total reflected energy. However the effective scattering coefficient of a surface depends not only on the roughness of the surface material indeed diffraction caused by limited dimensions of the surface as well as edge diffraction also causes scattering. For complex rooms it can be difficult to give a reasonable estimate to the magnitudes of scattering coefficients if these should also include diffraction and even if these frequency dependent coefficients could be obtained in the design phase, the processes of obtaining the data becomes quite time consuming thus increasing the cost of design. In this paper, practical methods to define scattering coefficients, which is based on an approach of modeling surface scattering and scattering caused by limited size of surface as well as edge diffraction are presented. The predicted and measured acoustic parameters in real rooms have been compared in order to verify the practical approaches recommended in the paper. [Copyright &y& Elsevier]

Abstract: Feature selection of noise sources is important for noise sources detection and classification. In this paper, a new rough set based feature selection method has been given. Based on the method, a noise sources automatic classification system (NSACS) has been designed and validated. The key idea of the method is that most effective features can distinguish the most number of samples belonging to different classes of noise sources, if they are used for classification. This new approach has been applied into the system NSACS to select relevant features for artificial datasets and real-world datasets and the results have shown that this approach can correctly select all the relevant features of artificial datasets and at the same time it can drastically reduce the number of features. From the experiments, it can be found that to consider all the five datasets, the number of classification features after selection drops to 35% and the accurate classification rate increases about 14%. For the underwater noise sources dataset the number of features drops to 1/5 and the accurate classification rate increases about 6% after feature selection. [Copyright &y& Elsevier]

A new feature selection method is proposed based on the discern matrix in rough set in this paper. The main idea of this method is that the most effective feature, if used for classification, can distinguish the most number of samples belonging to different class- es. Experiments are performed using this method to select relevant features for artificial datasets and real-world datasets. Results show that the selection method proposed can correctly select all the relevant features of artificial datasets and drastically reduce the number of features at the same time. In addition, when this method is used for the selection of classification features of real-world underwater targets, the number of classification features after selection drops to 20% of the original feature set, and the classification accuracy increases about 6 % using dataset after feature selection. [ABSTRACT FROM AUTHOR]

Underwater acoustic target recognition is extremely challenging because of the pronounced background noise and intricate sound propagation patterns inherent to maritime environments. Herein, we propose a sub-band concatenated Mel spectrogram to amplify low-frequency ship-radiated noise. This method enhances features through multispectrogram concatenation. Furthermore, we introduce a multidomain attention mechanism to enhance the performance of a simple residual network to develop a lightweight CFTANet model. The recognition accuracies of the recognition system are 90.60% and 96.40% on two open datasets. On the DeepShip dataset, the recognition accuracy is 7.06% higher than those of previous state-of-the-art methods. • A SC-Mel spectrogram method proposed for ship radiated noise characteristic enhancement. • The proposed CFTANet improves networks with multi-domain attention. • The UATR system tested on two public datasets, shows major gains on DeepShip dataset. • The CFTANet is lightweight and has the potential to be deployed on underwater unmanned platforms. [ABSTRACT FROM AUTHOR]

An accurate head-related transfer function can improve the subjective auditory localization performance of a particular subject. This paper proposes a deep neural network model for reconstructing the head-related transfer function (HRTF) based on anthropometric parameters and the orientation of the sound source. The proposed model consists of three subnetworks, including a one-dimensional convolutional neural network (1D-CNN) to process anthropometric parameters as input features and another network that takes the sound source position as input to serve as a marker. Finally, the outputs of these two networks are merged together as the input to a third network to estimate the HRTF. An objective method and a subjective method are proposed to evaluate the performance of the proposed method. For the objective evaluation, the root mean square error (RMSE) between the estimated HRTF and the measured HRTF is calculated. The results show that the proposed method performs better than a database matching method and a deep-neural-network-based method. In addition, the results of a sound localization test performed for the subjective evaluation show that the proposed method can localize sound sources with higher accuracy than the KEMAR dummy head HRTF or the DNN-based method. The objective and subjective results all show that the personalized HRTFs obtained using the proposed method perform well in HRTF reconstruction. [ABSTRACT FROM AUTHOR]

A new method of head-related transfer function (HRTF) personalization was built to optimize new user matching in the HRTF database to enhance 3D virtual hearing. The method of modified sparse representation (MSR) treated the HRTF personalization for an incomer as the task of finding similar subjects in the HRTF database with sparse representation (SR) of the incomer’s anthropometric features under the assumption that the equivalent sparse combination expresses the same anthropometric features and HRTFs for virtual hearing. The correlations among principal component coefficients and all anthropometric parameters were calculated after principal component analysis of the HRTF database for the same orientation. A derived database of anthropometric parameters was reconstructed, and SR was performed for all subjects in the original HRTF database. When the SR of the incomer was best matched with that of a subject in the derived database, the HRTF of the matched subject was used for the incomer’s 3D virtual hearing. The effect of MSR HRTF personalization was evaluated by spectral distortion. The results showed that the proposed method performed better than the others with the Chinese pilots database and the CIPIC database, especially in the frequency range of 0–8 kHz. [ABSTRACT FROM AUTHOR]

Objective: To compare and analyze the clinical efficacy and reproductive outcomes of the hysteroscopic tissue removal system (MyoSure) and hysteroscopic electroresection in the treatment of benign intrauterine lesions in women of reproductive age. Methods: This is a retrospective study of patients with benign intrauterine lesions treated with MyoSure or hysteroscopic electroresection. The primary outcomes were operative time and resection completeness, and reproductive outcomes were followed up and compared. Secondary outcomes included perioperative adverse events and postoperative adhesions seen during second‐look hysteroscopy. Data analysis was performed using χ2 and Fisher tests for qualitative variables and Student t‐test for quantitative variables. Results: The operative times of patients with type 0 or I myoma, endometrial polyps, or retained products of conception in the MyoSure group were shorter than those in the electroresection group but were not significantly different for patients with type II myomas. The complete resection rate was lower in the MyoSure group than in the electroresection group. The degree of decrease in the American Fertility Society score of intrauterine adhesion in the MyoSure group was significantly higher (2.90 ± 1.29 points vs 1.31 ± 0.89 points, P = 0.025). The time to pregnancy and the pregnancy rate were higher in the MyoSure group (13.14 ± 7.85 months vs 16.26 ± 8.22 months, P = 0.040; 65.12% vs 54.55%, P = 0.045), but there was no significant difference in the term live birth rate, premature birth rate, or abortion rate between the two groups. Conclusion: MyoSure has advantages of a shortened operative time and improvement in reproductive outcomes such as pregnancy rate. However, for type II myomas, MyoSure has limitations, and a comprehensive evaluation before the procedure is required. Synopsis: The MyoSure tissue removal procedure has advantages of a shortened operative time and improvement in endometrial healing and in reproductive outcomes such as pregnancy rate. [ABSTRACT FROM AUTHOR]

Five global monthly top-of-atmosphere (TOA) outgoing longwave radiation (OLR) products are evaluated in this study, including the products derived from the High-Resolution Infrared Radiation Sounder (HIRS), Clouds and the Earth's Radiant Energy System (CERES), Advanced Very High Resolution Radiometer (AVHRR), the CM SAF cLoud, Albedo and surface RAdiation dataset from AVHRR data (CLARA), and the Global Energy and Water Cycle EXchanges (GEWEX) project. Results show that overall there is good consistency among these five products. Larger differences are found between GEWEX and CERES (HIRS) after (before) 2000 (RMSE ~ 5 W/m2), particularly in the tropical regions. In terms of global mean values, GEWEX shows large differences with the other products from the year 1992 to 2002, and CLARA shows large differences from the year 1979 to 1981, which are more obvious in the global ocean values. Large discrepancies among these products exist at low latitudinal bands, particularly before the year 2000. Australia and Asia (mid–low latitude part) are two typical regions in which larger differences are found. [ABSTRACT FROM AUTHOR]

Sound field reproduction, which attempts to create a virtual acoustic environment, is a fundamental technology in the achievement of virtual reality. In sound field reproduction, the driving signals of the loudspeakers are calculated by considering the signals collected by the microphones and working environment of the reproduction system. In this paper, an end-to-end reproduction method based on deep learning is proposed. The inputs and outputs of this system are the sound-pressure signals recorded by microphones and the driving signals of loudspeakers, respectively. A convolutional autoencoder network with skip connections in the frequency domain is used. Furthermore, sparse layers are applied to capture the sparse features of the sound field. Simulation results show that the reproduction errors of the proposed method are lower than those generated by the conventional pressure matching and least absolute shrinkage and selection operator methods, especially at high frequencies. Experiments were performed under conditions of single and multiple primary sources. The results in both cases demonstrate that the proposed method achieves better high-frequency performance than the conventional methods. [ABSTRACT FROM AUTHOR]

• On the premise of the sparse target sound field, sparse plane wave decomposition as the decoding method of Ambisonics is used to reproduce sound field. • We compared the sparse plane wave decomposition decoding method with mode matching in 3D and 3D off-center reproduction and with sectorial mode matching in 2.5D sound field reproduction. • The sparse plane wave decoding method achieves lower reproduction error at high frequencies and ensures a larger sweet spot area. • In the investigated sweet spot area, a certain spatial correspondence with the target sound field maintains. • Applicable to sound field Ambisonics reproduction in reverberant environments. Sound field reproduction by loudspeaker array is an important way to create acoustical virtual reality. High order ambisonics (HOA) is a highly applicable method to reproduce a desired sound field with a loudspeaker array. For a target sound field that is represented by a group of harmonic coefficients, the process of calculating loudspeaker weights for reproduction with these harmonic coefficients is called decoding. Mode-matching based decoding is usually applied in HOA reproduction and good performance is achieved in the loudspeaker array center (the 'sweet spot'). However, the accuracy and sweet spot size are strongly affected by the recording order of the target sound field. To improve the reproduction performance, a new ambisonic decoding method is proposed based on the sparse plane wave decomposition in the case that the target sound field is steered by a small number of acoustic sources in this paper. The recorded target sound field is decomposed into a group of plane waves in the harmonic domain. Loudspeaker weights are calculated as a summation of the precalculated corresponding plane waves weights. Simulations are conducted in the free field and reverberation room to verify that the proposed method outperforms the mode-matching decoding. Experimental validation is conducted in a real listening room with a circular loudspeaker array. It is concluded that the reproduction error by the proposed method is superior to that by the sectorial mode matching for the investigated 2.5D reproduction case in the reverberant environment after 500 Hz and in terms of the MAC values, the proposed method ensures the spatial correspondence over frequency of the desired sound field and the reproduced sound field. [ABSTRACT FROM AUTHOR]

Top-of-atmosphere (TOA) outgoing longwave radiation (OLR), a key component of the Earth's energy budget, serves as a diagnostic of the Earth's climate system response to incoming solar radiation. However, existing products are typically estimated using the traditional two-step method, which may bring extra uncertainties. This paper presents a direct machine learning method to estimate TOA OLR by directly linking Himawari-8/Advanced Himawari Imager (AHI) TOA radiances with TOA OLR determined by Clouds and the Earth's Radiant Energy System (CERES) and other information, such as the viewing geometry. Models are built separately under clear- and cloudy-sky conditions using a gradient-boosting regression tree. Independent test results show that the root mean square errors (RMSEs) of the clear-sky and cloudy-sky models for estimating instantaneous values are 7.46 W/m2 (3.0%) and 11.61 W/m2 (5.8%), respectively. Daily results are obtained by averaging all the instantaneous results in one day. Intercomparisons of the daily results with CERES TOA OLR data show that the RMSE of the estimated AHI OLR is ~6 W/m2 (3%). The developed high-resolution AHI TOA OLR dataset will be beneficial in analyzing the regional energy budget. [ABSTRACT FROM AUTHOR]

An inverse wave modeling-based method is proposed for globally reconstructing the sound field in room environments. The method builds the wave model of the sound field as prior knowledge to support the reconstruction under strong reverberation. In this method, the whole space is divided into a set of subdomains. Based on the theory of discretization-based numerical simulation, a wave model that can describe the transfer characteristic between any subdomain and the source is built. Supported by this model, the sound source is recovered based on spatial sound pressure sampling and the global sound field reconstruction can be further accomplished in the reverberant environment. In particular, the shape function with the property of sparsity is constructed in building the wave model. Then, the intensity on the point source is represented by a sparse vector over the subdomains, and then, the sparse method can be used to achieve the recovery of this vector, which reduces the sampling burden in the space. Numerical verifications are performed to evaluate the performances of the proposed method. It demonstrates that the proposed method is capable of obtaining accurate reconstructions in a strong reverberant environment. It also shows that the method is applicable to problems with complicated excitations in the low-frequency range. [ABSTRACT FROM AUTHOR]

We report a kind of sound absorbing metastructure based on micro-perforated panel (MPP) and impedance matching coiled-up cavity (IMCC), which can broaden the low-frequency working bandwidth tremendously using single unit (e.g., 3.13 times compared to conventional designs) within a deep sub-wavelength thickness (e.g., ∼λ/20 at 322 Hz). Physically, impedance matching stemming from the dramatic cross-sectional area contrast of coiled-up channels reduces the acoustic reactance variation with respect to frequency, leading to broader low-frequency bandwidth. Theoretical predictions of sound absorption coefficients of the metastructure coincide well with the numerical and experimental results. The band broadening characteristics of the proposed IMCC are confirmed in relatively wide range of MPP parameters and partition panel positions. This work contributes to expanding the designing degrees of freedom for coiled-up metastructures to manipulate low-frequency waves in broadband. [ABSTRACT FROM AUTHOR]

Background: To investigate the clinical efficacy of the MyoSure hysteroscopic tissue removal system in the treatment of endometrial and cervical polyps in women with an intact hymen.Methods: Retrospective analysis was performed on the clinical data of 32 patients treated with the MyoSure hysteroscopic tissue removal system for endometrial and cervical polyps.Results: All the patients successfully completed the procedure. No intraoperative complications, such as cervical trauma, uterine perforation or TURP syndrome, were reported. The surgical time ranged from 5 to 35 min, with an average time of 19.3 min, and the intraoperative blood loss ranged from 2 to 50 ml with an average blood loss of 10.8 ml. After surgery, all patients were shown to have intact hymens. No residual polyp tissues were observed under the microscope, and abnormal uterine bleeding was relieved.Conclusions: The MyoSure hysteroscopic tissue removal system can be a safe and effective treatment for endometrial and cervical polyps in women with an intact hymen. [ABSTRACT FROM AUTHOR]

Sparse representation techniques have become increasingly promising for localizing the sound source in reverberant environment, where the multipath channel effects can be accurately characterized by the image model. In this paper, a dictionary is constructed by discretizing the inner space of the enclosure, which is parameterized by the unknown energy reflective ratio. More specifically, each atom of the dictionary can characterize a specific source-to-microphone multipath channel. Subsequently, source localization can be reformulated as a joint sparse signal recovery and parametric dictionary learning problem. In particular, a sparse Bayesian framework is utilized for modeling, where its solution can be obtained by variational Bayesian expectation maximization technique. Moreover, the joint sparsity in frequency domain is exploited to improve the dictionary learning performances. A remarkably advantage of this approach is that no laborious parameter tuning procedure is required and statistical information can be provided. Numerical simulation results have shown that the proposed algorithm achieves high source localization accuracy, low sidelobes and high robustness for multiple sources with low computational complexity in strong reverberant environments, compared with other state-of-the-art methods. [ABSTRACT FROM AUTHOR]

This study aims to explore the role of SKA1 in cancer diagnosis and prognosis and to investigate the mechanism by which SKA1 affects the malignant behaviors of ovarian cancer. Herein, we analyzed the oncogenic role of SKA1 at pan-cancer level by multiple informatics databases and verified the analysis by in vitro experiments. As a result, SKA1 was upregulated across cancers and was related to poor clinical outcome and immune infiltration. Specifically, the constructed nomogram showed superior performance in predicting the prognosis of epithelial ovarian cancer patients. Furthermore, the in vitro experiments revealed that silencing SKA1 significantly inhibited the proliferation, migratory ability and enhanced the cisplatin sensitivity of ovarian cancer cells. Therefore, we explored the oncogenic and potential therapeutic role of SKA1 across cancers through multiple bioinformatic analysis and revealed that SKA1 may promote ovarian cancer progression and chemoresistance to cisplatin by activating the AKT-FOXO3a signaling pathway. • This study provides a global introduction of SKA1 in pan-cancers using multi-omics database. • SKA1 is correlated with multiple immune cells and molecules, indicating the potential role in regulating tumor immune. • We further verified that SKA1 serve as an important oncogene and promote cancer cell progression through Akt/Foxo3a pathway. [ABSTRACT FROM AUTHOR]

• IMCCPs are consisting of coiled-up cavities and porous materials. • IMCCPs demonstrate marvelous broadband low-frequency sound absorption. • The feasibility of band broadening mechanism is validated for diverse parameters. • Good agreements are achieved among theoretical, numerical and experimental results. In this work, we propose a sound absorbing metastructure based on impedance matching coiled-up cavity embedded with porous materials (IMCCP), which demonstrates tremendous broadband (e.g., 4.55 times compared to conventional designs) low-frequency absorption capability with deep subwavelength thickness (e.g., ∼λ/10.96 at 602 Hz), without considering multiple units coupling. By tuning the geometric parameters of the non-coupled unit, relative bandwidths ranging from 111.07 % to 142.55 % are achieved. In particular, two notable perfect absorption peaks are obtained in the low- to mid-frequency range by changing the number of coiled-up channels. Theoretical predictions, numerical simulations and experimental measurements are conducted to investigate the acoustic characteristics of IMCCPs, and the results agree well with each other. Physically, the bandwidth broadening stems from the impedance matching effect which increases the degree of smoothness of sound wave propagation inside coiled-up space with strong inherent dissipation. The bandwidth broadening effect is generally confirmed for diverse geometrical and transport parameters of IMCCPs. This work contributes to understanding the sound wave propagation inside porous coiled-up space and designing broadband porous metastructures. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To analyze data from the hysteroscopic adhesiolysis of moderate-to-severe intrauterine adhesions (IUAs), and to review the disease etiology, changes in menstruation, uterine recovery, and reproductive prognosis of women after comprehensive therapy. Methods: In a retrospective descriptive analysis, clinical data were assessed from 683 patients with moderate-to-severe IUAs who were treated by hysteroscopic adhesiolysis at Third Xiangya Hospital, Changsha, China, between January 2007 and December 2011. Patients underwent comprehensive treatment. After hysteroscopic adhesiolysis, a persistent balloon urinary catheter was inserted, together with an intrauterine device (IUD). Intrauterine sodium hyaluronate gel was injected to prevent adhesion reformation, and oral estrogen was administered to promote endometrial regeneration. The outcomes were menstrual changes and uterine recovery under hysteroscopy, and the reproductive prognosis of patients with fertility intentions. Results: At the 3-month follow-up, the postoperative recovery of uterine shape was better than the recovery of menstruation among patients with moderate-to-severe IUAs. Among the 475 patients with fertility intentions, the pregnancy and live birth rates were 66.1% (314/475) and 64.0% (201/314), respectively. Conclusion: Comprehensive treatment prevented the recurrence of IUAs to a certain extent, but some severe endometrial injuries were found to be irreparable, reducing the rate of subsequent pregnancy and live birth. [Copyright &y& Elsevier]

[Display omitted] • The proposed porous glasses are fabricated through salt-mold-sintering method. • Semi-analytical model is higher efficient than conventional equivalent fluid model. • Good sound absorption performance is observed under thin sample thickness. • Wide range tailoring of sound absorption is realized regarding to micro-structures. This work reports a new kind of environment-friendly sound absorbent porous glasses, fabricated through salt-mold-sintering method without any poisonous substances discharging. A Johnson-Champoux-Allard-Lafarge theory based semi-analytical model is developed with the help of three micro-structure factors (i.e. Kozeny number, thermal and viscous pore shape factor), to explore the sound absorption characteristics of porous glasses highly efficiently. Comparisons between semi-analytically calculated transport parameters and numerically obtained ones, along with those between semi-analytical evaluated sound absorption coefficients and experimental measurements, validate the semi-analytical model's feasibility. All semi-analytical and experimental results show that the porous glasses possess high sound absorption with thin sample thickness. Moreover, based on the semi-analytical model, the sound absorption tailoring of porous glasses regarding to pore diameter, porosity and sample thickness is investigated. The porous glasses show great potential in modern noise reduction industry with severer environmental protection restrictions. [ABSTRACT FROM AUTHOR]

Objective: To assess the pathophysiologic composition and age structure of erectile dysfunction (ED) in men visiting outpatient clinics in China. Methods: We studied 3327 consecutive ED outpatients (median age 39 years) from 2006 to 2010 in the 5 training hospitals in China. Every patient was independently evaluated by an experienced urologist/andrologist using comprehensive diagnostic procedures. The simplified International Index of Erectile Function was used to assess the severity of ED. Results: Most patients (95.0%) were <60 years old, and none were >70 years old. The psychogenic patients were younger and had greater percentage than any other patients. Vasculogenic factors were a major etiology of organic ED. A significant difference was found in the age distribution between the patients with psychogenic ED and those with organic ED (P = .000). Diabetes, hypertension, coronary artery disease, and hyperlipidemia played significant roles in affecting the severity of ED in a statistical model, including age. The International Index of Erectile Function scores decreased with age (rs = −0.199, P = .000). Moreover, the percentage of severe and moderate cases increased with age (P = .003 and P = .002, respectively). However, the constituent ratio of patients sharply declined from 30.3% to 4.5% with age. Conclusion: The number of men visiting outpatient clinics with psychological ED is greater than the number with organic causes in China. The age of the Chinese patients with ED who seek medical help is young and this is mainly because of inadequate sex education to young men and because most older patients are reluctant to visit the hospital just for the loss of erectile function. [ABSTRACT FROM AUTHOR]