Search

During Hedgehog (Hh) signal transduction in development and disease, the atypical G protein-coupled receptor (GPCR) SMOOTHENED (SMO) communicates with GLI transcription factors by binding the protein kinase A catalytic subunit (PKA-C) and physically blocking its enzymatic activity. Here, we show that GPCR kinase 2 (GRK2) orchestrates this process during endogenous mouse and zebrafish Hh pathway activation in the primary cilium. Upon SMO activation, GRK2 rapidly relocalizes from the ciliary base to the shaft, triggering SMO phosphorylation and PKA-C interaction. Reconstitution studies reveal that GRK2 phosphorylation enables active SMO to bind PKA-C directly. Lastly, the SMO-GRK2-PKA pathway underlies Hh signal transduction in a range of cellular and in vivo models. Thus, GRK2 phosphorylation of ciliary SMO and the ensuing PKA-C binding and inactivation are critical initiating events for the intracellular steps in Hh signaling. More broadly, our study suggests an expanded role for GRKs in enabling direct GPCR interactions with diverse intracellular effectors. The hedgehog signal transduction pathway has an important role in development; it proceeds through the atypical GPCR protein SMOOTHENED (SMO), which regulates the transcription factor GLI by direct binding to PKA-C. This study shows that the GPCR kinase 2 activates SMO in primary cilia, allowing its binding to PKA-C and pathway activation in various cellular and in vivo models. [ABSTRACT FROM AUTHOR]

Winged fruits possess a unique flight mechanism relying on simple geometric structures rather than neuromuscular control. This study proposes an innovative approach using origami techniques to create three-winged model fruits, serving as a proxy for understanding the flight dynamics of natural winged fruits. Paper is employed to simulate inherent wing flexibility, with the option to add plastic frames for rigidity. We comprehensively investigate the free fall motion of both rigid and flexible winged fruits through experimental and numerical analyses. Velocity–time curves reveal a three-stage descent pattern—acceleration, deceleration, and steady states. The overshoot phenomenon is attributed to rapid lift increase due to leading-edge vortices attaching stably to the wings. This insight sheds light on aerodynamics governing fruit flight. Compared with rigid wings, flexible wings exhibit two key properties—slower descent and higher self-orienting capability—that facilitate a more stable and longer-distance dispersal of seeds under crosswind conditions. Our study demonstrates the potential benefits of flexible wings in natural seed distribution. This study advances our understanding of winged fruit flight dynamics, utilizing origami as a powerful tool for biomimetic investigations. The findings have broad implications, from improving aerodynamic designs to developing efficient micro air vehicles and electronic microfliers, and understanding seed dispersal evolution. [ABSTRACT FROM AUTHOR]

Contending with various recurrent congestion patterns on major freeway corridors has long been a prioritized task of the transportation community. Most of these patterns take place on a freeway interchange's on-ramp and off-ramp segments where both exiting and merging flows often trigger a series of lane changes, resulting in significant freeway speed reduction and propagation of traffic queues to neighboring surface streets. To concurrently mitigate freeway traffic congestion and minimize any negative impacts on the nearby local arterials, this study has developed an Integrated Real-time Interchange Control (IRIC) system, which maximizes the benefits of both freeway and arterial users by fusing an integrated off-ramp signal control (IOSC) module, an off-ramp queue impact (OQI) model, a lane group-based (LGB) traffic model, and a ramp metering control strategy as well as arterial signal optimization modules. The proposed system with both ramp metering functions and local arterial signal design capabilities can determine whether to implement system-wide optimization or merely the ramp metering based on real-time detected traffic conditions. The evaluation results from experiments have confirmed the effectiveness of the developed real-time interchange control system, especially with respect to its ability of preventing ramp queue overflows to the neighboring arterials and minimizing the off-ramp spillback onto the freeway mainline. [ABSTRACT FROM AUTHOR]

Most research on moving target defense has focused on how to efficiently change the IP address and the method of IP address replacement, and there have been few studies on the address-changing frequency, making it difficult for a user to decide the appropriate frequency for the system. According to previous research, the higher the address-changing frequency, the higher the system security at the expense of the performance of the server and the utilization of system resources. In this paper, we propose a method for quantifying the security of a moving target defense system that allows the user to decide the address-changing frequency in moving target defense. We show how to achieve the balance between security and system resource use by employing a stochastic process. Our research makes the moving target defense system operate more efficiently in industrial control systems. [ABSTRACT FROM AUTHOR]

On-ramp merging areas are congestion-prone segments of freeways. Depending on the aggressiveness of the driving population and the congestion level, the speed variance among travel lanes due to lane changes and ramp-merging flows may be so significant as to affect the optimal settings of deployed traffic control systems, such as metering rates or advisory speed limits. Extending from METANET, this study presents a lane group-based (LGB) traffic model to reflect the temporal and spatial distributions of traffic conditions among lane groups. The proposed model would allow traffic engineers to reliably assess the impacts of lane-changing activities in both upstream and downstream segments of an on-ramp area and better design their coordinated control strategies. To assess the effectiveness of the proposed model, this study has compared its performance with METANET under various traffic scenarios. The comparison results show that the proposed model can yield up to 26.9% improvement on the accuracy of predicting the temporal and spatial evolution of a freeway's speed at the interchange area where freeway segments often experience extensive lane-changing activities due to on-ramp merging flows. [ABSTRACT FROM AUTHOR]

The TLD-100H readout system performance under various radioactive I-131 exposure doses was optimized by four key factors via the revised Taguchi dynamic quality loss function. Taguchi dynamic analysis and the orthogonal array reorganizing the essential factors are crucial for the optimization of the thermoluminescent dosimeter (TLD) readout system given strict criteria of multiple irradiated environments and long-term exposure for calibrated TLDs. Accordingly, 96 TLD-100H chips were selected and randomly categorized into three batches with eight groups (four TLD chips in each group). Four factors, namely (1) initial temperature, (2) heating rate, (3) maximal temperature, and (4) TLD preheat time before reading were organized into eight combinations according to Taguchi suggestion, whereas each factor was preset at two levels. All 96 (3 × 8 × 4 = 9 6) chips were put in three concentric circles with 30, 60, and 90 cm radii for 48 h, surrounding the radioactive 150 mCi (5. 5 5 × 1 0 3 MBq) I-131 capsule and exposed to the cumulative doses of 88.2, 18.6, and 8.6 mSv for the respective radii, accordingly. The TLD readings obtained from each group were analyzed to derive the sensitivity, coincidence, and reproducibility, then those were reorganized to draw four fish-bone-plots for the optimization. The optimal option for the TLD readout system implied the combination of A1 (a 1 3 5 ∘ C initial temperature), B1 (a 1 0 ∘ C/s heating rate), C1 (a 2 4 0 ∘ C maximal temperature), and D2 (a 15 s preheat time), which was further verified by the follow-up measurements. The dominant factors were A (initial temperature) and B (heating rate), whereas C (maximal temperature) and D (preheat time) were minor and provided negligible contributions to the system performance optimization. [ABSTRACT FROM AUTHOR]

Biokinetic model of Tc-99m MIBI for eight patients undergone myocardial perfusion examination was studied using gamma camera and MATLAB program. A six-compartment model was adopted to interpret the metabolic mechanism of each patient. Within the model framework, the respective set of simultaneous differential equations was solved by a self-developed program run in MATLAB. The experimental results exhibited a good fit with the theoretical predictions via the model. The average biological half-lives of body fluid, heart, thyroid, liver, GI Tract and remainder were assessed as 3. 3 ± 1. 1 , 0. 6 ± 0. 3 , 0. 2 ± 0. 2 , 1 1. 7 ± 0. 0 , 0. 4 ± 0. 2 , and 1 8. 3 ± 1. 1 h, respectively. A dimensionless AT index of disagreement between the experimental data and MATLAB optimal solution was proposed of validating the applied acquisition system and analytical method feasibility. An AT of zero implies a perfect agreement between the theoretical and empirical results, while averages of the derived AT were fluctuated from 3 ± 2 to 2 5 ± 1 8 for five compartments. The proposed refined equation estimated the internal dose from gamma-ray as 3. 3 8 ± 2. 5 8 mSv for eight patients according to a fast screening method, which defined human body as a spherical ball to simplify the calculation in reality. The proposed MATLAB-based fitting of in-vivo data with the theoretical results was instrumental for assessing the radiation dose received by the Tc-99m MIBI scan participants. [ABSTRACT FROM AUTHOR]

Maintaining appropriate insulin levels is very important for diabetes patients. Effective monitoring of blood glucose can aid in maintaining the body's insulin level, and thus reduce disease severities, secondary complications, and related mortalities. However, existing blood glucose measurement devices are inconvenient to carry and involve complex procedures, reducing the willingness of diabetes patients to regularly measure blood glucose. We aim to provide a rapid, convenient, and portable meter for diabetes patients. We introduce an integrated blood glucose detection device (IBGDD) that has no electronic component and uses the optical sensing module of a smartphone to inspect colorimetric blood strips. To demonstrate accuracy conformance of the developed device to the ISO 15197:2013 standard for blood glucose measurement, 20 diabetes mellitus patients used the IBGDD with smartphones to measure their blood glucose level. The measurement results revealed an accuracy of 100%, completely satisfying the requirements of the ISO 15197:2013 standard. Overall, our specially designed IBGDD with a smartphone could achieve high accuracy and convenient usage for the measurement of blood glucose concentration. Furthermore, the device is highly portable and simple to operate. This contributes toward achieving self-monitoring of blood glucose by diabetes patients and improved mobile health in the future. [ABSTRACT FROM AUTHOR]

The laser-initiated thermal (optothermal) switching of cholesteric liquid crystals (CLCs) is characterized by using different azobenzene (Azo) derivatives and laser wavelengths. Under 405-nm laser irradiation, Azo-doped CLCs undergo phase transition from cholesteric to isotropic. No cis-to-trans photoisomerization occurs when the 405-nm laser irradiation is blocked because only a single laser is used. The fast response of Azo-doped CLCs under the on--off switching of the 405-nm laser occurs because of the optothermal effect of the system. The 660-nm laser, which cannot be used as irradiation to generate the trans-cis photoisomerization of Azo, is used in Anthraquinone (AQ)-Azo-doped CLCs to examine the optothermal effect of doped Azo. The results show that the LC-like Azo derivative bearing two methyl groups ortho to the Azo moiety (A4) can greatly lower the clearing temperature and generate large amount of heat in AQ-A4-doped CLCs. [ABSTRACT FROM AUTHOR]

Screening cDNA libraries for genes encoding proteins that interact with a bait protein is usually performed in yeast. However, subcellular compartmentation and protein modification may differ in yeast and plant cells, resulting in misidentification of protein partners. We used bimolecular fluorescence complementation technology to screen a plant cDNA library against a bait protein directly in plants. As proof of concept, we used the N-terminal fragment of yellow fluorescent protein– or nVenus-tagged Agrobacterium tumefaciens VirE2 and VirD2 proteins and the C-terminal extension (CTE) domain of Arabidopsis thaliana telomerase reverse transcriptase as baits to screen an Arabidopsis cDNA library encoding proteins tagged with the C-terminal fragment of yellow fluorescent protein. A library of colonies representing ∼2 × 105 cDNAs was arrayed in 384-well plates. DNA was isolated from pools of 10 plates, individual plates, and individual rows and columns of the plates. Sequential screening of subsets of cDNAs in Arabidopsis leaf or tobacco (Nicotiana tabacum) Bright Yellow-2 protoplasts identified single cDNA clones encoding proteins that interact with either, or both, of the Agrobacterium bait proteins, or with CTE. T-DNA insertions in the genes represented by some cDNAs revealed five novel Arabidopsis proteins important for Agrobacterium -mediated plant transformation. We also used this cDNA library to confirm VirE2-interacting proteins in orchid (Phalaenopsis amabilis) flowers. Thus, this technology can be applied to several plant species. [ABSTRACT FROM AUTHOR]

The question of whether discontinuous DNA replication operates only for the lagging strand or for both strands in E. coli remains unresolved. In this study, the participation of priA, B, C and rep genes in discontinuous DNA replication was examined by analyzing the size distribution of nascent DNA synthesized in wild-type, lig-7 and polA4113 genetic backgrounds. Inactivation of priA, but not priB, priC or rep, resulted in a significant increase of high molecular weight (HMW) DNA in the short pulse-labeled DNA in the wild-type lig polA strains. Inactivation of priA also produced a significant increase of HMW DNA in the nascent DNA synthesized in lig-7 and polA4113 strains. These results indicate that PriA is involved in the discontinuous synthesis of nascent DNA. [ABSTRACT FROM AUTHOR]

The multicolor absorption of MOS SiGe/Si quantum-dot (QD) infrared photodetectors is demonstrated using the boron delta-doping in Si spacers. The energy-dispersive X-ray spectroscopy shows that the Ge concentration in the wetting layers is much smaller than that in QDs. Most holes stay at the ground state in QDs instead of wetting layers. The energy band structure in QDs is calculated to understand the absorption spectrum. The absorption at 3.7-6 mum is due to the intersubband transition in the SiGe QDs. The other absorption at 6-16 mu m mainly comes from the intraband transition in the boron delta-doping wells. Since the broadband spectrum covers most of the atmospheric transmission windows for infrared, the broadband detection is feasible using this device. [ABSTRACT FROM PUBLISHER]

BACKGROUND: Adopting thrombolytic therapy with tissue plasminogen activator (tPA) in clinical practice presents many challenges. One major factor is the restrictive time window of 0-3 hours after symptom onset, for the commencement of treatment. OBJECTIVE: To test the efficacy of a newly developed plasminogen activator (human tissue urokinase type plasminogen activator [HTUPA]) for the treatment of acute ischaemic stroke within 5 hours of symptom onset. DESIGN: An open-label, dose escalation trial. The initial dose was 0.3 mg/kg and could be increased or decreased depending on tolerability. SETTING: Three teaching hospitals in Taiwan. PARTICIPANTS: Thirty-three patients who presented with National Institute of Health Stroke Scale (NIHSS) scores of between 9 and 20, who had evidence of ischaemic stroke confirmed by CT. MAIN OUTCOMES MEASURES: Efficacy was assessed by the NIHSS, the Modified Rankin Scale (MRS), the Barthel Index and the Glasgow Outcome Scale. Preliminary efficacy endpoints included major neurological improvement at 24 hours and favourable outcome at 90 days after administration of HTUPA. RESULTS: Of the 33 patients who received HTUPA, 29 received 0.3 mg/kg, 3 received 0.35 mg/kg and 1 received 0.4 mg/kg. Major neurological improvement, defined as improvement of ⩾4 points on the NIHSS 24 hours after treatment, was observed in 45% of all patients treated (15/33) and in 48% (14/29) of those treated with 0.3 mg/kg. Ninety days after symptom onset, in those who received HTUPA 0.3 mg/kg, the proportion of patients with a favourable outcome was 34% on the NIHSS (⩽1), 45% on the MRS (0 or 1), 41% on the Barthel Index (⩾95) and 45% on the Glasgow Outcome Scale (1). Eighty six percent of the patients treated with 0.3 mg/kg within 0-3 hours of symptom onset reached scores of 0-1 on both the NIHSS and the MRS. CONCLUSIONS: Approximately 50% of patients treated with HTUPA 0.3 mg/kg within a 5-hour window after symptom onset experienced major neurological improvement within 24 hours of drug administration. Thrombolytic agents, in this case HTUPA, may be suitable for Taiwanese or Asian patients with acute ischaemic stroke who meet the inclusion criteria. [ABSTRACT FROM AUTHOR]

A thin dual-band internal patch antenna for Global System for Mobile Communication, 890-960 MHz/Digital Communication System, 1710-1880 MHz (GSM/DCS) operation in a Personal Digital Assistant (PDA) phone is presented. The antenna can generate two wide resonant modes for GSM (890-960 MHz) and DCS (1710-1880 MHz) operation, yet it requires an air-layer substrate of thickness 4 mm only, which is among the thinnest internal mobile phone antennas that have been reported. The antenna's top patch comprises a resonant narrow strip supporting a longer resonant path for GSM operation and a resonant subpatch supporting a shorter resonant path for DCS operation. By including a suitable widened end portion for the narrow strip and a suitable tapered end portion for the subpatch, increased bandwidths for the proposed thin internal mobile phone antenna are obtained. Detailed design considerations of the proposed antenna are described. In addition, the user's hand effects on the performances of the proposed antenna are studied. [ABSTRACT FROM AUTHOR]

In this work, an 8 × 8 Discrete Cosine Transform (DCT) approach is adopted to perform DCT shrinkage, followed by modified set partitioning in hierarchical trees (SPIHT) data organization and fidelity enhancement filter for reducing the memory required to store a remote diagnosis and rapidly transmit it. The DCT shrinkage has the ability to retain the detailed characteristics of an image. By means of a simple transformation to gather the DCT spectrum data with the same frequency domain, the DCT shrinkage exploits all the characteristics of individual blocks to a global framework. In this scheme, insignificant DCT coefficients that correspond to the same spatial location in the high-frequency sub-bands can be used to reduce the redundancy by a combined function proposed in association with the modified SPIHT. Meanwhile, quad-tree decomposition and a set of morphological filters for reducing the artifacts are presented. This set of filters employs 8 predefined morphological operations, namely 4 structuring elements (SE), each of which includes both dilation and erosion operations. The voting strategy is used to select the most suitable morphological filter for each block. Simulation results show that the image compression reduced the computational complexity to only a half of the wavelet based sub-band decomposition and improved the quality of the reconstructed medical image in terms of both the peak signal-to-noise ratio (PSNR) and the perceptual results close to JPEG2000 and the original SPIHT at the same bit rate. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 49–61, 2007 [ABSTRACT FROM AUTHOR]

Increasing the bandwidth or bit rate in real-time video applications to improve the quality of images is typically impossible or too expensive. Postprocessing appears to be the most feasible solution because it does not require any existing standards to be changed. Markedly reducing blocking effects can increase compression ratios for a particular image quality or improve the quality with respect to the specific bit rate of compression. This paper proposes a novel deblocking algorithm based on three filtering modes in terms of the activity across block boundaries. By properly considering the masking effect of the human visual system, an adaptive filtering decision is integrated into the deblocking process. According to three different deblocking modes appropriate for local regions with different characteristics, the perceptual and objective quality are improved without over smoothing the image details or insufficient reducing the strong blocking effect on the flat region. According to the simulation results, the proposed method outperforms methods of deblocking MPEG-4 with respect to peak signal-to-noise ratios and computational complexity. [ABSTRACT FROM AUTHOR]

This paper proposes a mobile patient monitoring system, which integrates current personal digital assistant (PDA) technology and wireless local area network (WLAN) technology. At the patient's location, a wireless PDA-based monitor is used to acquire continuously the patient's vital signs, including heart rate, three-lead electrocardiography, and SpO2. Through the WLAN, the patient's biosignals can be transmitted in real-time to a remote central management unit, and authorized medical staffs can access the data and the case history of the patient, either by the central management unit or the wireless devices. A prototype of this system has been developed and implemented. The system has been evaluated by technical verification, clinical test, and user survey. The evaluation of performance yields a high degree of satisfaction (mean = 4.64, standard deviation—SD = 0.53 in a five-point Likert scale) of users who used the PDA-based system for intrahospital transport. The results also show that the wireless PDA model is superior to the currently used monitors both in mobility and in usability, and is, therefore, better suited to patient transport. [ABSTRACT FROM AUTHOR]

Background: Radiofrequency catheter ablation for paroxysmal atrial fibrillation is well established but not drawback free. Pulmonary vein stenosis is one of the complications and usually treated with stenting with the disadvantages of high re-stenosis rate and anticoagulant dependence.Case Presentation: Herein, we present the case of a 47 year-old lady, who suffered from fever and hemoptysis due to right inferior pulmonary vein occlusion after radiofrequency catheter ablation for paroxysmal atrial fibrillation. Eventually, thoracoscopic right lower lung lobectomy was inevitable with satisfactory result.Conclusions: Pulmonary vein stenosis is a major complication after radiofrequency ablation of atrial fibrillation. High suspicion and early detection in patients with pulmonary manifestations are mandatory for salvage the injured lung in early. If delayed, surgical resection of the involved lung, especially through the thoracoscopic approach will eradicate the problem with minimal complication. [ABSTRACT FROM AUTHOR]

G protein-coupled receptors (GPCRs), which regulate a vast number of eukaryotic processes, are desensitized by various mechanisms but, most importantly, by the GPCR kinases (GRKs). Ever since GRKs were first identified, investigators have sought to determine which structural features of GRKs are used to select for the agonist-bound states of GPCRs and how this binding event in turn enhances GRK catalytic activity. Despite a wealth of molecular information from high-resolution crystal structures of GRKs, the mechanisms driving activation have remained elusive, in part because the GRK N-terminus and active site tether region, previously proposed to serve as a receptor docking site and to be key to kinase domain closure, are often disordered or adopt inconsistent conformations. However, two recent studies have implicated other regions of GRKs as being involved in direct interactions with active GPCRs. Atomic resolution structures of GPCR–GRK complexes would help refine these models but are, so far, lacking. Here, we assess three distinct models for how GRKs recognize activated GPCRs, discuss limitations in the approaches used to generate them, and then experimentally test a hypothetical GPCR interaction site in GRK2 suggested by the two newest models. [ABSTRACT FROM AUTHOR]

Single-crystalline Ge p-channel thin-film transistors with Schottky-barrier source/drain (S/D) on flexible polyimide substrates are fabricated by a simple low-temperature process (≤ 250 °C), which preserves the high mobility of Ge channel. Adhesive wafer bonding and Smart-Cut techniques were utilized to transfer the single-crystalline Ge thin film onto polyimide substrates. The Schottky-barrier S/D is formed by using Pt/n-Ge contact, showing a low hole barrier height. The device has a linear hole mobility of ~170 cm² ⋅ V-1 ⋅ s-1 and a saturation current ~1.6 µA/µm at Vd = -1.5 V for the channel length and width of 15 and 280 µm, respectively. [ABSTRACT FROM AUTHOR]

A printed diversity dual-band planar inverted-F antenna (PIFA) mounted vertically at the edge of a PCMCIA network card (such that the protruded portion of the network card from the housing of the laptop has a minimum length) for WLAN operation in the 2.4-GHz band (2400–2484 MHz) and 5.2-GHz band (5150–5350 MHz) is presented. The diversity antenna studied comprises two back-to-back stacked PIFAs and has a low profile of 10 mm to the network card. Across the two operating bands, the measured reflection coefficient S11 and isolation S21 are all less than -14 dB (1.5:1 VSWR) and -24 dB, respectively. In addition, the measured radiation patterns of the two stacked PIFAs in general cover complementary space regions, thereby making it possible for providing spatial diversity for WLAN operation. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 223–225, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11020 [ABSTRACT FROM AUTHOR]

This paper presents a low-profile broadband design of a printed quadrifilar helical antenna for the application as a broadcasting satellite receiving antenna in the frequency range of about 2.3 to 2.7 GHz. The antenna comprises four parallel printed strips excited in phase quadrature and rolled into a helical shape on a foam cylinder of diameter 22 mm and height 27.2 mm. The antenna shows broadband circular polarization (CP) operation with a 3-dB axial-ratio bandwidth of about 670 MHz or 27.9% centered at about 2.4 GHz. Good antenna gain is also obtained. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 134–136, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10698 [ABSTRACT FROM AUTHOR]

By bending a planar monopole into an inverted-U shape and short-circuiting one end to the ground, a novel low-profile monopole antenna with reduced backward radiation is obtained. The proposed antenna is easily fed by using a capacitively coupled feed, and is suitable for applications in mobile phones for providing reduced radiation toward the user's head. A prototype of the proposed antenna for DCS operation (1710–1880 MHz) is constructed, and measured and simulated results are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 146–147, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10258 [ABSTRACT FROM AUTHOR]

A low-temperature (LT) AlGaN interlayer is inserted in the Al0.1Ga0.9N back barrier layer of an Al0.2Ga0.8N/GaN/Al0.1Ga0.9N double heterostructure grown on a 150 mm Si substrate. It is found that the 21-nm-thick LT-AlGaN interlayer plays an important role in stress relaxation and dislocation reduction of the Al0.1Ga0.9N back barrier layer, especially for screw dislocation reduction. In addition, a buffer breakdown voltage higher than 600 V is achieved, which is much higher than those of conventional heterostructures. These results demonstrate the effectiveness of combining the LT-AlGaN interlayer and the Al0.2Ga0.8N/GaN/Al0.1Ga0.9N double heterostructure on a Si substrate to increase the breakdown voltage for high-power applications. [ABSTRACT FROM AUTHOR]

The blocking effect is the major drawback in discrete cosine transform (DCT)-based codecs at low bit rates. When a high compression ratio is required, boundaries between adjacent image blocks become visible. This kind of degradation probably will affect the judgment of an end user. In this work, a four-neighboring-block zero-masking technique is proposed in the DCT frequency domain. The proposed algorithm uses a shift block within four adjacent DCT blocks to reduce computational complexity. By slightly modifying several DCT coefficients in the shift block, the artifacts that result from quantization and dequantization processes are alleviated. The simulation results show that both visual perception and objective image quality are noticeably improved. [ABSTRACT FROM AUTHOR]