Search Results (38)

This paper presents a multiscale histogram excess-distribution strategy addressing the structural limitations (i.e., insufficient dark-region restoration, block artifacts, ringing effects, color distortion, and saturation loss) of contrast-limited adaptive histogram equalization (CLAHE) and retinex-based image-contrast enhancement techniques. This method adjusts the ratio between the uniform and weighted distribution of the histogram excess based on the average tile brightness. At the coarsest scale, excess pixels are redistributed to histogram bins initially occupied by pixels, maximizing detail restoration in dark areas. For medium and fine scales, the contrast enhancement strength is adjusted according to tile brightness to preserve local luminance transitions. Scale-specific lookup tables are bilinearly interpolated and merged at the pixel level. Background restoration corrects unnatural tone compression by referencing the original image, ensuring visual consistency. A ratio-based chroma adjustment and color-restoration function compensate for saturation degradation in retinex-based approaches. An asymmetric Gaussian offset correction preserves structural information and expands the global dynamic range. The experimental results demonstrate that this method enhances local and global contrast while preserving fine details in low light and high brightness. Compared with various existing methods, this method reproduces more natural color with superior image enhancement. Full article

To address the triple bottlenecks of data scarcity, oversized models, and slow inference that hinder Cantonese automatic speech recognition (ASR) in low-resource and edge-deployment settings, this study proposes a cost-effective Cantonese ASR system based on LoRA fine-tuning and INT8 quantization. First, Whisper-tiny is parameter-efficiently fine-tuned on the Common Voice zh-HK training set using LoRA with rank = 8. Only 1.6% of the original weights are updated, reducing the character error rate (CER) from 49.5% to 11.1%, a performance close to full fine-tuning (10.3%), while cutting the training memory footprint and computational cost by approximately one order of magnitude. Next, the fine-tuned model is compressed into a 60 MB INT8 checkpoint via dynamic quantization in ONNX Runtime. On a MacBook Pro M1 Max CPU, the quantized model achieves an RTF = 0.20 (offline inference 5 × real-time) and 43% lower latency than the FP16 baseline; on an NVIDIA A10 GPU, it reaches RTF = 0.06, meeting the requirements of high-concurrency cloud services. Ablation studies confirm that the LoRA-INT8 configuration offers the best trade-off among accuracy, speed, and model size. Limitations include the absence of spontaneous-speech noise data, extreme-hardware validation, and adaptive LoRA structure optimization. Future work will incorporate large-scale self-supervised pre-training, tone-aware loss functions, AdaLoRA architecture search, and INT4/NPU quantization, and will establish an mJ/char energy–accuracy curve. The ultimate goal is to achieve CER ≤ 8%, RTF < 0.1, and mJ/char < 1 for low-power real-time Cantonese ASR in practical IoT scenarios. Full article

High-frequency (h. f.) harmonic distortion (HD) of advanced SiGe heterojunction bipolar transistor (HBT)-based power cells (PwCs), featuring optimized metallization interconnections between individual HBTs, was investigated. Single tone input power (P_in) excitations at 1, 2, 5, and 10 GHz frequencies were employed. The output power (P_out) of the fundamental tone and its harmonics were analyzed in both the frequency and time domains. A rapid increase in the third harmonic of P_out was observed at input powers exceeding −8 dBm for a fundamental frequency of 10 GHz in two different PwC technologies. This increase in the third harmonic was analyzed in terms of nonlinear current waveforms, the nonlinearity of the HBT p-n junction diffusion capacitances, substrate current behavior versus P_in, and avalanche multiplication current. To assess the RF power performance of the PwCs, scalar and vectorial load-pull (LP) measurements were conducted and analyzed. Under matched conditions, the SiGe PwCs demonstrated good linearity, particularly at high frequencies. The key power performance of the PwCs was measured and simulated as follows: input power 1 dB compression point (P_{in_1dB}) of −3 dBm, transducer power gain (G_T) of 15 dB, and power added efficiency (PAE) of 50% at 30 GHz. All measured data were corroborated with simulations using the compact model HiCuM L2. Full article

Background: Myofascial trigger points (MTrPs) are hyperirritable spots within taut bands of skeletal muscle fibers, often developing in overloaded muscles. Ischemic compression (IC) is a frequently used therapeutic technique for MTrP treatment. Material and Methods: Seventy-nine participants with MTrPs in the upper trapezius muscle were included. Three IC protocols were used. In group 1, the compression force was increased once; in group 2, twice; and in group 3, three times—each time up to the pain threshold, then held constant until the pain subsided. Evaluations included pressure pain threshold (PPT), pressure pain perception (PPP), and myotonometric measurements. Results: PPT values increased significantly in group 2 (p = 0.009) and group 3 (p = 0.009), while PPP values decreased significantly in both groups (group 2: p = 0.016; group 3: p = 0.041) post-intervention. Group 1 showed a significant reduction in muscle tone (p < 0.001), and group 2 in muscle stiffness (p = 0.036). Muscle elasticity significantly improved in all groups: group 1 (p = 0.022), group 2 (p = 0.001), and group 3 (p = 0.042). Conclusions: IC applied with a constant force at the individual’s pain perception threshold effectively elevates the pain threshold and enhances the biomechanical parameters of muscle fibers in the trigger point area. Full article

In this study, pharmacotherapies of abdominal compartment syndrome (ACS) and intra-abdominal hypertension (IAH) in animal studies were reviewed from the perspective of ACS/IAH as failed cytoprotection issues, as non-specific injuries, and from the point of view of the cytoprotection concept as resolution. Therefore, this review challenges the unresolved theoretical and practical issues of severe multiorgan failure, acknowledged significance in clinics, and resolving outcomes (i.e., open abdomen). Generally, the reported agents not aligned with cytoprotection align with current pharmacotherapy limitations and have (non-)confirmed effectiveness, mostly in only one organ, mild/moderate IAH, prophylactic application, and provide only a tentative resolution. Contrarily, stable gastric pentadecapeptide BPC 157 therapy, as a novel and relevant cytoprotective mediator having pleiotropic beneficial effects, simultaneously resolves many targets, resolving established disturbances, specifically compression/ischemia (grade III and grade IV), and decompression/advanced reperfusion. BPC 157 therapy rapidly activates collateral bypassing pathways, and, in ACS and IAH, and later, in reperfusion, there is a “bypassing key” (i.e., azygos vein direct blood flow delivery). This serves to counteract multiorgan and vessel failure, including lesions and hemorrhages in the brain, heart, lung, liver, kidney and gastrointestinal tract, thrombosis, peripherally and centrally, intracranial (superior sagittal sinus), portal and caval hypertension and aortal hypotension, occlusion/occlusion-like syndrome, advanced Virchow triad circumstances, and free radical formation acting as a membrane stabilizer and free radical scavenger. Likewise, not only in ACS/IAH resolving, but also in other occlusion/occlusion-like syndromes, this “bypassing key” could be an effect of the essential endothelial cytoprotective capacity of BPC 157 and a particular modulatory effect on the NO-system, and a rescuing impact on vasomotor tone. Full article

Digital Imaging and Communication in Medicine (DICOM) is a standard format for storing medical images, which are typically represented in higher bit depths (10–16 bits), enabling detailed representation but exceeding the display capabilities of standard displays and human visual perception. To address this, DICOM images are often accompanied by windowing parameters, analogous to tone mapping in High-Dynamic-Range image processing, which compress the intensity range to enhance diagnostically relevant regions. This study evaluates traditional histogram-based methods and explores the potential of deep learning for predicting window parameters in radiographs where such information is missing. A range of architectures, including MobileNetV3Small, VGG16, ResNet50, and ViT-B/16, were trained on high-bit-depth computed radiography images using various combinations of loss functions, including structural similarity (SSIM), perceptual loss (LPIPS), and an edge preservation loss. Models were evaluated based on multiple criteria, including pixel entropy preservation, Hellinger distance of pixel value distributions, and peak-signal-to-noise ratio after 8-bit conversion. The tested approaches were further validated on the publicly available GRAZPEDWRI-DX dataset. Although histogram-based methods showed satisfactory performance, especially scaling through identifying the peaks in the pixel value histogram, deep learning-based methods were better at selectively preserving clinically relevant image areas while removing background noise. Full article

Image visibility is often degraded under challenging conditions such as low light, backlighting, and inadequate contrast. To mitigate these issues, techniques like histogram equalization, high dynamic range (HDR) tone mapping and near-infrared (NIR)–visible image fusion are widely employed. However, these methods have inherent drawbacks: histogram equalization frequently causes oversaturation and detail loss, while visible–NIR fusion requires complex and error-prone images. The proposed algorithm of a complementary cycle-consistent generative adversarial network (CycleGAN)-based training with visible and NIR images, leverages CycleGAN to generate fake NIR images by blending the characteristics of visible and NIR images. This approach presents tone compression and preserves fine details, effectively addressing the limitations of traditional methods. Experimental results demonstrate that the proposed method outperforms conventional algorithms, delivering superior quality and detail retention. This advancement holds substantial promise for applications where dependable image visibility is critical, such as autonomous driving and CCTV (Closed-Circuit Television) surveillance systems. Full article

Background: The study aimed to evaluate the immediate effect of Heat-Compression-Therapy with Game Ready equipment (GR-HCT) on biomechanical properties at different treatment times. Reducing the duration of stimulation through HCT can help optimize recovery processes in sports. Methods: Twenty male MMA fighters (26.5 ± 4.5 years, BMI 24.75 ± 3.0, training experience: 10.3 ± 5.0 years) performed two experimental sessions: (a) 5 min heat-compression therapy (HCT) stimulation (GR-HCT-5); and (b) 10 min heat-compression therapy (GR-HCT-10). All registered parameters, tissue perfusion (PU), tissue temperature (°C), muscle tone (T-Hz) stiffness (S—N/m), elasticity (E—arb), pressure pain threshold (PPT—N/cm) and isometric muscle strength (Fmax—kgf), were measured at rest (r—2 min before GR-HCT stimulation) and 1 min after GR-HCT (p-post) for the flexor carpi radialis muscle (MFCR) and the brachioradialis muscle (MBR). Results: The Friedman’s test for MBR revealed significant differences between GR-HCT5min vs. GR-HCT10min for PU (p < 0.0001), S (p = 0.008), and for MBR and MFCR for °C (p < 0.0001). The pairwise comparisons for PU, S, and °C showed significant differences between rest vs. post values for 5 min as well as between rest vs. post values for 10 min. Further, there was a significant interaction effect (5 min-10 min × Rest-Post p < 0.0001) for PU for MFCR. The post hoc comparison for the interaction effect showed significantly higher PU for post- compared to premeasurement in 5 min PU and 10 min PU (p < 0.001). Further, there was a significant main effect of condition for Fmax both for MFCR and MBR (5 min vs. 10 min p < 0.001); The post hoc comparison for the main effect of condition showed a significantly higher Fmax for post- compared to premeasurement in 5 min and 10 min (p < 0.001). Further, there was a significant main effect of condition for pressure pain threshold [N/cm] both for MFCR and MBR and for T for MBR time of measurement rest vs. post (p < 0.001; p = 0.006; p < 0.001, respectively). The post hoc comparison for the interaction effect showed a significantly lower PPT for post vs. rest in 5 min (p < 0.001 only for MFCR) and in 10 min (p < 0.001). The delta values for PU (post-rest) and ΔTemp °C showed significant differences between the 5 min and 10 min conditions (MFCR; p < 0.0001); (MBR p < 0.001) and (MFCR p < 0.0001); (MBR p < 0.001). Conclusion: Our results show that GR-HCT significantly affects recovery of muscle biomechanical parameters, pain threshold, strength, tissue perfusion, and temperature. Our findings show that a 5 min effect can be sufficient when compared to a 10 min one which is a clue for designing effective recovery protocols. Full article

In this study, a broadband linearizer design method based on an extended design space is proposed to optimize the design complexity and linearization performance of conventional linearizers for broadband operation. The gain characteristics of the power amplifier (PA) and linearizer are fitted to simplify the analyses and to quickly derive the ideal objective function of the linearizer design. Then, the 1 dB compression point of a nonlinear system is redefined and used to further extend the design space of the linearizer. To verify the proposed design method, a millimeter-wave linearizer prototype based on the extended design space was designed and fabricated. The linearizer was tested with continuous-wave and 100 MHz two-tone signals from 40 GHz to 43 GHz. The measurement results of the linearized PA showed that the output 1 dB power point ($O{P}_{1dB}$) was improved by more than 1.7 dB, the phase error was reduced by more than 15$°$, and the third-order intermodulation distortion (IMD3) was suppressed by 8.6 dB–13.1 dB over the working frequencies. The proposed linearizer achieved good linearization performance, low power consumption, and simple design implementation, and it was not necessary to tune the bias during broadband operation, making it applicable in complex communication scenarios. Full article

Tone-mapping algorithms aim to compress a wide dynamic range image into a narrower dynamic range image suitable for display on imaging devices. A representative tone-mapping algorithm, Retinex theory, reflects color constancy based on the human visual system and performs dynamic range compression. However, it may induce halo artifacts in some areas or degrade chroma and detail. Thus, this paper proposes a Retinex jointed multiscale contrast limited adaptive histogram equalization method. The proposed algorithm reduces localized halo artifacts and detail loss while maintaining the tone-compression effect via high-scale Retinex processing. A performance comparison of the experimental results between the proposed and existing methods confirms that the proposed method effectively reduces the existing problems and displays better image quality. Full article

Background: It is assumed that speech comprehension deficits in background noise are caused by age-related or acquired hearing loss. Methods: We examined young, middle-aged, and older individuals with and without hearing threshold loss using pure-tone (PT) audiometry, short-pulsed distortion-product otoacoustic emissions (pDPOAEs), auditory brainstem responses (ABRs), auditory steady-state responses (ASSRs), speech comprehension (OLSA), and syllable discrimination in quiet and noise. Results: A noticeable decline of hearing sensitivity in extended high-frequency regions and its influence on low-frequency-induced ABRs was striking. When testing for differences in OLSA thresholds normalized for PT thresholds (PTTs), marked differences in speech comprehension ability exist not only in noise, but also in quiet, and they exist throughout the whole age range investigated. Listeners with poor speech comprehension in quiet exhibited a relatively lower pDPOAE and, thus, cochlear amplifier performance independent of PTT, smaller and delayed ABRs, and lower performance in vowel-phoneme discrimination below phase-locking limits (/o/-/u/). When OLSA was tested in noise, listeners with poor speech comprehension independent of PTT had larger pDPOAEs and, thus, cochlear amplifier performance, larger ASSR amplitudes, and higher uncomfortable loudness levels, all linked with lower performance of vowel-phoneme discrimination above the phase-locking limit (/i/-/y/). Conslusions: This study indicates that listening in noise in humans has a sizable disadvantage in envelope coding when basilar-membrane compression is compromised. Clearly, and in contrast to previous assumptions, both good and poor speech comprehension can exist independently of differences in PTTs and age, a phenomenon that urgently requires improved techniques to diagnose sound processing at stimulus onset in the clinical routine. Full article

A tone mapping operator (TMO) is a module in the image signal processing pipeline that is used to convert high dynamic range images to low dynamic range images for display. Currently, state-of-the-art TMOs typically take complex algorithms and are implemented on graphics processing units, making it difficult to run with low latency on edge devices, and TMOs implemented in hardware circuits often lack additional noise suppression because of latency and hardware resource constraints. To address these issues, we proposed a low-latency noise-aware TMO for hardware implementation. Firstly, a locally weighted guided filter is proposed to decompose the luminance image into a base layer and a detail layer, with the weight function symmetric concerning the central pixel value of a window. Secondly, the mean and standard deviation of the basic layer and the detail layer are used to estimate the noise visibility according to the human visual characteristics. Finally, the gain for the detail layer is calculated to achieve adaptive noise suppression. In this process, luminance is first processed by the log2 function before being filtered and then symmetrically converted back to the linear domain by the exp2 function after compression. Meanwhile, the algorithms within the proposed TMO were optimized for hardware implementation to minimize latency and cache, achieving a low latency of 60.32 $\mathsf{\mu }\mathrm{s}$ under video specification of 1080 P at 60 frames per second and objective metric smoothness in dark flat regions could be improved by more than 10% compared to similar methods. Full article

Mixed martial arts (MMA) fighters use their arms and hands for striking with the fists, grappling, and defensive techniques, which puts a high load on the forearms and hand muscles. New methods are needed to decrease the risk of injury and increase the effectiveness of regeneration. This study aimed to assess the effectiveness of cryo-compression (CC) therapy of different times (3 and 6 min) on forearm muscles in MMA fighters by investigating muscle pain, stiffness, tension, elasticity strength, and perfusion. Twenty professional male MMA fighters aged 26.5 ± 4.5 years, with training experience of 10.3 ± 5.0 years, were enrolled on an experimental within-group study design. The participants underwent CC therapy at a temperature of 3 °C and compression of 75 mmHg for 3 min and, in the second session, for 6 min. The investigated parameters were in the following order: (1) perfusion in non-reference units (PU), (2) muscle tone (T—[Hz]), (3) stiffness (S—[N/m]), (4) elasticity (E—[arb]), (5) pressure pain threshold (PPT—[N/cm]), and (6) maximum isometric force (Fmax [kgf]) at two time points: (1) at rest—2 min before CC therapy (pre) and (2) 2 min after CC therapy (post). There were significant differences between 3 and 6 min of CC therapy for PU and T. Meanwhile, F, E, PPT, and S were significantly different when comparing pre- to post-conditions. These results provide evidence that CC therapy is a stimulus that significantly affects parameters characterizing muscle biomechanical properties, pain threshold, strength, and tissue perfusion. Full article

The noise radiated by the flow around a cylinder in the subcritical regime at $R{e}_D=1\times {10}^4$ and at a subsonic Mach number of $M=0.5$ is here studied. The aerodynamic sound radiated by a cylinder has been studied with a wide range of Reynolds numbers, but there are no studies about how the Mach number affects the acoustic field in the subsonic regime. The flow field is resolved by means of large-eddy simulations of the compressible Navier–Stokes equations. For the study of the noise propagation, formulation 1C of the Ffowcs Williams–Hawkings analogy is used. The fluid flow results show good agreement when comparing the surface pressure coefficient, the recirculation length, the vortex shedding frequency and the force coefficients against other studies performed under similar conditions. The dynamic mode decomposition of the pressure fluctuations is used to relate them with the far-field noise. It is shown that, in contrast to what happens for low Mach numbers, quadrupoles have a significant impact mainly in the observers located in the streamwise direction. This effect leads to a global monopole directivity pattern as the shear fluctuations compensate for the lower value of the aeolian tone away from the cross-stream direction. Full article

In computational photography, high dynamic range (HDR) imaging refers to the family of techniques used to recover a wider range of intensity values compared to the limited range provided by standard sensors. Classical techniques consist of acquiring a scene-varying exposure to compensate for saturated and underexposed regions, followed by a non-linear compression of intensity values called tone mapping. Recently, there has been a growing interest in estimating HDR images from a single exposure. Some methods exploit data-driven models trained to estimate values outside the camera’s visible intensity levels. Others make use of polarimetric cameras to reconstruct HDR information without exposure bracketing. In this paper, we present a novel HDR reconstruction method that employs a single PFA (polarimetric filter array) camera with an additional external polarizer to increase the scene’s dynamic range across the acquired channels and to mimic different exposures. Our contribution consists of a pipeline that effectively combines standard HDR algorithms based on bracketing and data-driven solutions designed to work with polarimetric images. In this regard, we present a novel CNN (convolutional neural network) model that exploits the underlying mosaiced pattern of the PFA in combination with the external polarizer to estimate the original scene properties, and a second model designed to further improve the final tone mapping step. The combination of such techniques enables us to take advantage of the light attenuation given by the filters while producing an accurate reconstruction. We present an extensive experimental section in which we validate the proposed method on both synthetic and real-world datasets specifically acquired for the task. Quantitative and qualitative results show the effectiveness of the approach when compared to state-of-the-art methods. In particular, our technique exhibits a PSNR (peak signal-to-noise ratio) on the whole test set equal to 23 dB, which is $18\%$ better with respect to the second-best alternative. Full article