Resource Cluster-Based Resource Search and Allocation Scheme for Vehicular Clouds in Vehicular Ad Hoc Networks.

Vehicular clouds represent an appealing approach, leveraging vehicles' resources to generate value-added services. Thus, efficiently searching for and allocating resources is a challenge for the successful construction of vehicular clouds. Many recent schemes have relied on hierarchical network architectures using clusters to address this challenge. These clusters are typically constructed based on vehicle proximity, such as being on the same road or within the same region. However, this approach struggles to rapidly search for and consistently allocate resources, especially considering the diverse resource types and varying mobility of vehicles. To address these limitations, we propose the Resource Cluster-based Resource Search and Allocation (RCSA) scheme. RCSA constructs resource clusters based on resource types rather than vehicle proximity. This allows for more efficient resource searching and allocation. Within these resource clusters, RCSA supports both intra-resource cluster search for the same resource type and inter-resource cluster search for different resource types. In RCSA, vehicles with longer connection times and larger resource capacities are allocated in vehicular clouds to minimize cloud breakdowns and communication traffic. To handle the reconstruction of resource clusters due to vehicle mobility, RCSA implements mechanisms for replacing Resource Cluster Heads (RCHs) and managing Resource Cluster Members (RCMs). Simulation results validate the effectiveness of RCSA, demonstrating its superiority over existing schemes in terms of resource utilization, allocation efficiency, and overall performance.

Multiple Precaching Vehicle Selection Scheme Based on Set Ranking in Intermittently Connected Vehicular Networks.

In vehicular networks, vehicles download vehicular information for various applications, including safety, convenience, entertainment, and social interaction, from the corresponding content servers via stationary roadside units. Since sufficient RSUs might be difficult to deploy due to rough geographical conditions or high deployment costs, vehicular networks can feature uncovered outage zones between two neighboring RSUs. In these outage zones, vehicles cannot download content, and thus the vehicle networks are defined as intermittently connected vehicular networks. In intermittently connected vehicular networks, the download delay and traffic overhead on the backhaul links are increased due to the large size of the content requested by vehicle users and the long distances between RSUs. Using the mobility information of vehicles, several schemes have been proposed to solve this issue by precaching and relaying content via multiple relaying vehicles in the outage zone. However, because they involved the individual ranking of vehicles for precaching and allocated all of the available precaching amounts to the top-ranking vehicles, they decreased the success rate of content requests and the fairness of vehicle precaching. To overcome the problem of these previous schemes, this paper proposes a multiple precaching vehicle selection (MPVS) scheme that efficiently selects a content-precaching vehicle group with multiple precaching vehicles to precache relayed content in outage zones. To achieve this, we first designed numerical models to decide the necessity and the amount of precaching and to calculate the available precaching amounts of vehicles. Next, MPVS calculates all available vehicle sets and ranks each set based on the available precaching amount. Then, the content-precaching vehicle group is identified from the sets by considering both set rankings and vehicle communication overheads. MPVS also provides a content downloading process through the content-precaching vehicle group in the outage zone. Simulation results conducted in various environments with a content request model and a highway mobility model verified that MPVS was superior to a representative previous scheme.

Implicit Overhearing Node-Based Multi-Hop Communication Scheme in IoT LoRa Networks.

Long range (LoRa) is a low-power wide-area technology because it is eminent for robust long-distance, low-bitrate, and low-power communications in the unlicensed sub-GHz spectrum used for the Internet of things (IoT) networks. Recently, several multi-hop LoRa networks have proposed schemes with explicit relay nodes to partially mitigate the path loss and longer transmission time bottlenecks of the conventional single-hop LoRa by focusing more on coverage expansion. However, they do not consider improving the packet delivery success ratio (PDSR) and the packet reduction ratio (PRR) by using the overhearing technique. Thus, this paper proposes an implicit overhearing node-based multi-hop communication (IOMC) scheme in IoT LoRa networks, which exploits implicit relay nodes for performing the overhearing to promote relay operation while satisfying the duty cycle regulation. In IOMC, implicit relay nodes are selected as overhearing nodes (OHs) among end devices with a low spreading factor (SF) in order to improve PDSR and PRR for distant end devices (EDs). A theoretical framework for designing and determining the OH nodes to execute the relay operations was developed with consideration of the LoRaWAN MAC protocol. Simulation results verify that IOMC significantly increases the probability of successful transmission, performs best in high node density, and is more resilient to poor RSSI than the existing schemes.

Effects of a Metacognitive Smartphone Intervention With Weekly Mentoring Sessions for Individuals With Schizophrenia: A Quasi-Experimental Study.

Application (app)-based interventions using smartphones could provide effective alternatives to traditional treatment programs during and beyond the coronavirus disease 2019 pandemic. The current quasi-experimental study with a non-equivalent comparison group tested the effects of a smartphone app-based metacognitive intervention program with weekly mentoring sessions on the meta-cognitive beliefs, psychotic symptoms, and social functioning of individuals with schizophrenia from community psychosocial rehabilitation centers. The study was conducted with 20 participants with severe psychotic symptoms and low social functioning and 24 participants with relatively light psychotic symptoms and good social functioning as a comparison group. For the experimental group, the app-based intervention was combined with weekly contact mentoring sessions over 10 weeks. The comparison group received only the app-based intervention over 10 weekly sessions. No differences were observed between groups' total scores; however, the experimental group showed a tendency toward improved psychotic symptoms and social functioning over time, unlike the comparison group. These findings provide an empirical basis for managing schizophrenia symptoms with smartphone apps. [Journal of Psychosocial Nursing and Mental Health Services, 61(2), 27-37.].

Highly-packed self-assembled graphene oxide film-integrated resistive random-access memory on a silicon substrate for neuromorphic application.

Resistive random-access memories (RRAMs) based on metal-oxide thin films have been studied extensively for application as synaptic devices in neuromorphic systems. The use of graphene oxide (GO) as a switching layer offers an exciting alternative to other materials such as metal-oxides. We present a newly developed RRAM device fabricated by implementing highly-packed GO layers on a highly doped Si wafer to yield a gradual modulation of the memory as a function of the number of input pulses. By using flow-enabled self-assembly, highly uniform GO thin films can be formed on flat Si wafers in a rapid and simple process. The switching mechanism was explored through proposed scenarios reconstructing the density change of the sp2cluster in the GO layer, resulting in a gradual conductance modulation. We analyzed that the current in a low resistance state could flow by tunneling or hopping via clusters because the distance between the sp2clusters in closely-packed GO layers is short. Finally, through a pattern-recognition simulation with a Modified National Institute of Standards and Technology database, the feasibility of using close-packed GO layers as synapse devices was successfully demonstrated.

SF-Partition-Based Clustering and Relaying Scheme for Resolving Near-Far Unfairness in IoT Multihop LoRa Networks.

Long range (LoRa) is one of the most successful low-power wide-area networking technologies because it is ideally suited for long-distance, low-bit rate, and low-power communications in the unlicensed sub-GHz spectrum utilized for Internet of things (IoT) networks. The effectiveness of LoRa depends on the link budget (i.e., spreading factor (SF), bandwidth (BW), and transmission power (TX)). Due to the near-far effect, the allocation of a link budget to LoRa devices (LDs) in large coverage regions is unfair between them depending on their distance to the GW. Thus, more transmission opportunities are given to some LDs to the detriment of other LD's opportunities. Numerous studies have been conducted to address the prevalent near-far fairness problem. Due to the absence of a tractable analytical model for fairness in the LoRa network, however, it is still difficult to solve this problem completely. Thus, we propose an SF-partition-based clustering and relaying (SFPCR) scheme to achieve enormous LD connectivity with fairness in IoT multihop LoRa networks. For the SF partition, the SFPCR scheme determines the suitable partitioning threshold point for bridging packet delivery success probability gaps between SF regions, namely, the lower SF zone (LSFZ) and the higher SF zone (HSFZ). To avoid long-distance transmissions to the GW, the HSFZ constructs a density-based subspace clustering that generates clusters of arbitrary shape for adjacent LDs and selects cluster headers by using a binary score representation. To support reliable data transmissions to the GW by multihop communications, the LSFZ offers a relay LD selection that ideally chooses the best relay LD to extend uplink transmissions from LDs in the HSFZ. Through simulations, we show that the proposed SFPCR scheme exhibits the highest success probability of 65.7%, followed by the FSRC scheme at 44.6%, the mesh scheme at 34.2%, and lastly the cluster-based scheme at 29.4%, and it conserves the energy of LDs compared with the existing schemes.

Video Packet Distribution Scheme for Multimedia Streaming Services in VANETs.

By leveraging the development of mobile communication technologies and due to the increased capabilities of mobile devices, mobile multimedia services have gained prominence for supporting high-quality video streaming services. In vehicular ad-hoc networks (VANETs), high-quality video streaming services are focused on providing safety and infotainment applications to vehicles on the roads. Video streaming data require elastic and continuous video packet distributions to vehicles to present interactive real-time views of meaningful scenarios on the road. However, the high mobility of vehicles is one of the fundamental and important challenging issues for video streaming services in VANETs. Nevertheless, previous studies neither dealt with suitable data caching for supporting the mobility of vehicles nor provided appropriate seamless packet forwarding for ensuring the quality of service (QoS) and quality of experience (QoE) of real-time video streaming services. To address this problem, this paper proposes a video packet distribution scheme named Clone, which integrates vehicle-to-vehicle and vehicle-to-infrastructure communications to disseminate video packets for video streaming services in VANETs. First, an indicator called current network quality information (CNQI) is defined to measure the feature of data forwarding of each node to its neighbor nodes in terms of data delivery ratio and delay. Based on the CNQI value of each node and the trajectory of the destination vehicle, access points called clones are selected to cache video data packets from data sources. Subsequently, packet distribution optimization is conducted to determine the number of video packets to cache in each clone. Finally, data delivery synchronization is established to support seamless streaming data delivery from a clone to the destination vehicle. The experimental results show that the proposed scheme achieves high-quality video streaming services in terms of QoS and QoE compared with existing schemes.

Adaptive Content Precaching Scheme Based on the Predictive Speed of Vehicles in Content-Centric Vehicular Networks.

Content-Centric Vehicular Networks (CCVNs) are considered as an attractive technology to efficiently distribute and share contents among vehicles in vehicular environments. Due to the large size of contents such as multimedia data, it might be difficult for a vehicle to download the whole of a content within the coverage of its current RoadSide Unit (RSU). To address this issue, many studies exploit mobility-based content precaching in the next RSU on the trajectory of the vehicle. To calculate the amount of the content precaching, they use a constant speed such as the current speed of the vehicle requesting the content or the average speed of vehicles in the next RSU. However, since they do not appropriately reflect the practical speed of the vehicle in the next RSU, they could incorrectly calculate the amount of the content precaching. Therefore, we propose an adaptive content precaching scheme (ACPS) that correctly estimates the predictive speed of a requester vehicle to reflect its practical speed and calculates the amount of the content precaching using its predictive speed. ACPS adjusts the predictive speed to the average speed starting from the current speed with the optimized adaptive value. To compensate for a subtle error between the predictive and the practical speeds, ACPS appropriately adds a guardband area to the precaching amount. Simulation results verify that ACPS achieves better performance than previous schemes with the current or the average speeds in terms of the content download delay and the backhaul traffic overhead.

The Effect of Three Surgical Therapies to Increase Keratinized Mucosa Surrounding Dental Implants with Peri-Implantitis: A Pilot Study.

Background and Objectives: The purpose of this pilot study was to evaluate the clinical outcomes of three different methods for increasing the keratinized mucosa (KM) surrounding dental implants with peri-implantitis. Materials and methods: Twenty implant sites with peri-implantitis were divided into: (1) porcine collagen matrix (CM) group: seven implant sites; (2) apically positioned flap (APF) group: eight implant sites; and (3) free gingival graft (FGG) group: five implant sites. The KM width and clinical parameters (probing pocket depth (PPD) and bleeding on probing (BOP)) were measured at time points: before surgery (T0) and 30 (T1), 60 (T2), 90 (T3), and 180 (T4) days after surgery. Results: Regarding KM width, all the groups had significant differences for increasing horizontal and vertical KM width. The CM and FGG groups had greater KM than the APF group. There was a decrease in PPD in all three groups. APF and FGG showed significant differences in PPD at T1 and T2 compared to T0. Only the FGG group showed a significant difference in PPD at T3 and T4 compared with that at T0. BOP values were also reduced in all the groups at T1-T4 compared to T0. The APF and FGG groups showed a significant decrease in BOP. Conclusions: Three surgical therapies presented favorable results for increasing the KM surrounding implants. Compared with the FGG group, the CM showed similar results in increasing the KM around the dental implants with peri-implantitis.

Evaluating Change of Marginal Bone Height with Cone-Beam Computed Tomography Following Surgical Treatment with Guided Tissue Regeneration (Bone Grafting) or Access Flap Alone: A Retrospective Study.

Background and Objectives: This study aimed to evaluate the change of bone height following treatment of human intrabony defects with guided tissue regeneration (GTR) with bone grafting or access flap alone by cone-beam computed tomography (CBCT) scan. Materials and methods: This study was conducted as a retrospective longitudinal study. In this study, a total of 2281 teeth sites were included: the GTR group had 1210 sites, and the Flap group had 1071 sites. In the GTR group, demineralized freeze-dried bone (DFDBA) particles in combination with resorbable collagen membrane were used. No regenerative material was applied to the Flap group. CBCT images were taken twice at baseline and at least 2.5 months postoperatively. Bone heights were measured using software on CBCT images. Results: The bony change between the GTR and Flap groups was significantly different (p = 0.00001). Both males and females in the GTR group had smaller bone loss than in the Flap group. In age groups, significant differences of bony height between the GTR and Flap groups were observed in the subgroups consisting of those 29-45 and 46-53 years old. The non-smoking subjects in the GTR group had higher bone heights than those in the Flap group. In the absence of systemic disease and medicine, bone formation was higher in the GTR group than in the Flap group. In terms of oral position, the #14-17, #34-37, and #44-47 subgroups of the GTR group showed higher levels of bone heights than those of the Flap group. Conclusions. The results of this study indicated that the GTR procedure offers the additional benefit of higher bone heights than the Flap procedure does.

Navigation-assisted anchor insertion in shoulder arthroscopy: a validity study.

BACKGROUND: This study aimed to compare conventional and navigation-assisted arthroscopic rotator cuff repair in terms of anchor screw insertion. METHODS: The surgical performance of five operators while using the conventional and proposed navigation-assisted systems in a phantom surgical model and cadaveric shoulders were compared. The participating operators were divided into two groups, the expert group (n = 3) and the novice group (n = 2). In the phantom model, the experimental tasks included anchor insertion in the rotator cuff footprint and sutures retrieval. A motion analysis camera system was used to track the surgeons' hand movements. The surgical performance metric included the total path length, number of movements, and surgical duration. In cadaveric experiments, the repeatability and reproducibility of the anchor insertion angle were compared among the three experts, and the feasibility of the navigation-assisted anchor insertion was validated. RESULTS: No significant differences in the total path length, number of movements, and time taken were found between the conventional and proposed systems in the phantom model. In cadaveric experiments, however, the clustering of the anchor insertion angle indicated that the proposed system enabled both novice and expert operators to reproducibly insert the anchor with an angle close to the predetermined target angle, resulting in an angle error of < 2° (P = 0.0002). CONCLUSION: The proposed navigation-assisted system improved the surgical performance from a novice level to an expert level. All the experts achieved high repeatability and reproducibility for anchor insertion. The navigation-assisted system may help surgeons, including those who are inexperienced, easily familiarize themselves to of suture anchors insertion in the right direction by providing better guidance for anchor orientation. LEVEL OF EVIDENCE: A retrospective study (level 2).

Investigation of Multi-Level Cell Characteristic in Amorphous Indium-Gallium-Zinc Oxide Thin-Film-Transistor Based 1T-1R Non-Volatile Memory Device.

In this work, we have implemented nonvolatile resistive random access memory (ReRAM) cells consisting of one transistor (1T) and one resistor (1R) configuration by integrating a high-performance InGaZnO (IGZO) thin-film-transistor (TFT) and an HfO2 resistive switching component on a single substrate for system-on-panel (SoP) technology. ReRAM cells with a 1T-1R configuration can reduce undesired crosstalk caused by leakage current between adjacent memory cells. The a-IGZO TFTs used for 1T-1R integration showed excellent electrical characteristics with a high field-effect mobility of 10.8 cm²/V s, a low subthreshold swing of 226 mV/dec and a large on-off current ratio of 9.2 × 107. The 1T-1R integrated memory cells exhibited BRS behavior, uniform distribution of resistance states and operating voltage, stable DC endurance and reliable data retention characteristics. In addition, we obtained MLC characteristics in a 1T-1R integrated memory cell by controlling the driving current with the gate voltage of a-IGZO TFTs. In multi-level operation, it showed a low operating voltage of 1 V, stable endurance and reliable retention characteristics at 85 °C.

Improving Charge Trapping/Detrapping Characteristics of Amorphous In-Ga-ZnO Thin-Film-Transistors Using Microwave Irradiation.

We investigated the effect of post-deposition annealing (PDA) on the gate-bias-stress-induced charge trapping/detrapping phenomenon in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). To evaluate device reliability, we used the microwave irradiation (MWI), rapid thermal annealing (RTA), and conventional thermal annealing (CTA) methods for PDA of the TFTs and compared the resulting device performances. Fabricated devices were measured in the dark and under light illumination under positive and negative gate-bias-temperature stress (PBTS and NBTS, respectively). Because microwave energy was transferred directly to the substrate in a short time of 2 min in the MWI device, defects were removed more effectively. The obtained results indicated that the threshold voltage (Vth) shift of the MWI-treated a-IGZO TFT with different temperatures and gate bias stresses in the dark and under light illumination was the smallest and the most reliable. Further, comparisons of the Vth recovery characteristics in the dark and under light illumination indicated that charge detrapping behaviors were enhanced under the latter condition. Furthermore, the average effective energy barrier based on Arrhenius plots was extracted. Therefore, the MWI method is considered promising for fabricating next-generation displays on various substrates.

Vertical Tunnel Field-Effect Transistor with Polysilicon Layer.

In this paper, a novel structure of tunnel field-effect transistors (TFETs) is proposed. The proposed device has an intrinsic polysilicon layer located in the overlap region between the source and the gate, which can increase the tunneling area and overcome the low ON-current drawback of the conventional TFET. The advantages of the proposed device are proven by using technology computeraided design (TCAD) simulation. It exhibits more than 50 higher on-current (ION) of 0.13 µA/µm and lower subthreshold swing (SS) of 53 mV/dec than a conventional planar TFET. In addition, the effect of some device parameters on the device performance has been investigated.

Tracking Accuracy of a Stereo Camera-Based Augmented Reality Navigation System for Orthognathic Surgery.

PURPOSE: Tracking accuracy is critical to successful augmented reality (AR) in the diagnosis and surgical correction of maxillofacial deformities. The present study investigated the tracking accuracy of an AR navigation system combined with a stereo camera during repositioning of the maxilla after a Le Fort I osteotomy using a 3-dimensional skull model and compared the tracking accuracy with that of an existing infrared (IR)-based optical tracking system (OTS). MATERIALS AND METHODS: Five maxillary surgery plans were designed using a 6 degrees-of-freedom articulator that allowed maxillary movement to be set up quantitatively (target distance, 5 mm). To evaluate the accuracy of the stereo camera AR navigation system, it was compared with a commercially available and commonly used IR-based OTS. RESULTS: The mean error was 0.0584 mm in the IR-based OTS and 0.0596 mm in the AR navigation system. The mean accuracy was 98.83% in the IR-based OTS and 98.81% in the AR navigation system. CONCLUSIONS: In this study, the stereo camera-based AR navigation system fabricated and analyzed by the authors was designed for accuracy. The experiments showed its reliability and accuracy. The hardware developed for this AR navigation system displayed accuracy similar to that of existing high-cost imported devices at a substantially lower cost. In addition to surgery, potential applications of the AR navigation system include patient communication and training for novice clinicians.

Navigation-assisted suture anchor insertion for arthroscopic rotator cuff repair.

BACKGROUND: Suture anchor placement for subscapularis repair is challenging. Determining the exact location and optimum angle relative to the subscapularis tendon direction is difficult because of the mismatch between a distorted arthroscopic view and the actual anatomy of the footprint. This study aimed to compare the reliability and reproducibility of the navigation-assisted anchoring technique with conventional arthroscopic anchor fixation. METHODS: Arthroscopic shoulder models were tested by five surgeons. The conventional and navigation-assisted methods of suture anchoring in the subscapularis footprint on the humeral head were tested by each surgeon seven times. Angular results and anchor locations were measured and compared using the Wilcoxon signed rank test. Interobserver intraclass correlation coefficients (ICCs) were analyzed among the surgeons. RESULTS: The mean angular errors of the targeted anchor fixation guide without and with navigation were 17° and 2° (p < 0.05), respectively, and the translational errors were 15 and 3 mm (p < 0.05), respectively. All participants showed a narrow range of anchor fixation angular and translational errors from the original target. Among the surgeons, the interobserver reliabilities of angular errors for ICCs of the navigation-assisted and conventional methods were 0.897 and 0.586, respectively, and the interobserver ICC reliabilities for translational error were 0.938 and 0.619, respectively. CONCLUSIONS: The navigation system may help surgeons be more aware of the surrounding anatomy and location, providing better guidance for anchor orientation, including footprint location and anchor angle.

Can Augmented Reality Be Helpful in Pelvic Bone Cancer Surgery? An In Vitro Study.

BACKGROUND: Application of surgical navigation for pelvic bone cancer surgery may prove useful, but in addition to the fact that research supporting its adoption remains relatively preliminary, the actual navigation devices are physically large, occupying considerable space in already crowded operating rooms. To address this issue, we developed and tested a navigation system for pelvic bone cancer surgery assimilating augmented reality (AR) technology to simplify the system by embedding the navigation software into a tablet personal computer (PC). QUESTIONS/PURPOSES: Using simulated tumors and resections in a pig pelvic model, we asked: Can AR-assisted resection reduce errors in terms of planned bone cuts and improve ability to achieve the planned margin around a tumor in pelvic bone cancer surgery? METHODS: We developed an AR-based navigation system for pelvic bone tumor surgery, which could be operated on a tablet PC. We created 36 bone tumor models for simulation of tumor resection in pig pelves and assigned 18 each to the AR-assisted resection group and conventional resection group. To simulate a bone tumor, bone cement was inserted into the acetabular dome of the pig pelvis. Tumor resection was simulated in two scenarios. The first was AR-assisted resection by an orthopaedic resident and the second was resection using conventional methods by an orthopaedic oncologist. For both groups, resection was planned with a 1-cm safety margin around the bone cement. Resection margins were evaluated by an independent orthopaedic surgeon who was blinded as to the type of resection. All specimens were sectioned twice: first through a plane parallel to the medial wall of the acetabulum and second through a plane perpendicular to the first. The distance from the resection margin to the bone cement was measured at four different locations for each plane. The largest of the four errors on a plane was adopted for evaluation. Therefore, each specimen had two values of error, which were collected from two perpendicular planes. The resection errors were classified into four grades: ≤ 3 mm; 3 to 6 mm; 6 to 9 mm; and > 9 mm or any tumor violation. Student's t-test was used for statistical comparison of the mean resection errors of the two groups. RESULTS: The mean of 36 resection errors of 18 pelves in the AR-assisted resection group was 1.59 mm (SD, 4.13 mm; 95% confidence interval [CI], 0.24-2.94 mm) and the mean error of the conventional resection group was 4.55 mm (SD, 9.7 mm; 95% CI, 1.38-7.72 mm; p < 0.001). All specimens in the AR-assisted resection group had errors < 6 mm, whereas 78% (28 of 36) of errors in the conventional group were < 6 mm. CONCLUSIONS: In this in vitro simulated tumor model, we demonstrated that AR assistance could help to achieve the planned margin. Our model was designed as a proof of concept; although our findings do not justify a clinical trial in humans, they do support continued investigation of this system in a live animal model, which will be our next experiment. CLINICAL RELEVANCE: The AR-based navigation system provides additional information of the tumor extent and may help surgeons during pelvic bone cancer surgery without the need for more complex and cumbersome conventional navigation systems.

Susceptibility-weighted imaging: current status and future directions.

Susceptibility-weighted imaging (SWI) is a method that uses the intrinsic nature of local magnetic fields to enhance image contrast in order to improve the visibility of various susceptibility sources and to facilitate diagnostic interpretation. It is also the precursor to the concept of the use of phase for quantitative susceptibility mapping (QSM). Nowadays, SWI has become a widely used clinical tool to image deoxyhemoglobin in veins, iron deposition in the brain, hemorrhages, microbleeds and calcification. In this article, we review the basics of SWI, including data acquisition, data reconstruction and post-processing. In particular, the source of cusp artifacts in phase images is investigated in detail and an improved multi-channel phase data combination algorithm is provided. In addition, we show a few clinical applications of SWI for the imaging of stroke, traumatic brain injury, carotid vessel wall, siderotic nodules in cirrhotic liver, prostate cancer, prostatic calcification, spinal cord injury and intervertebral disc degeneration. As the clinical applications of SWI continue to expand both in and outside the brain, the improvement of SWI in conjunction with QSM is an important future direction of this technology. Copyright © 2016 John Wiley & Sons, Ltd.

A hands-free region-of-interest selection interface for solo surgery with a wide-angle endoscope: preclinical proof of concept.

BACKGROUND: A hands-free region-of-interest (ROI) selection interface is proposed for solo surgery using a wide-angle endoscope. A wide-angle endoscope provides images with a larger field of view than a conventional endoscope. With an appropriate selection interface for a ROI, surgeons can also obtain a detailed local view as if they moved a conventional endoscope in a specific position and direction. METHODS: To manipulate the endoscope without releasing the surgical instrument in hand, a mini-camera is attached to the instrument, and the images taken by the attached camera are analyzed. When a surgeon moves the instrument, the instrument orientation is calculated by an image processing. Surgeons can select the ROI with this instrument movement after switching from 'task mode' to 'selection mode.' The accelerated KAZE algorithm is used to track the features of the camera images once the instrument is moved. Both the wide-angle and detailed local views are displayed simultaneously, and a surgeon can move the local view area by moving the mini-camera attached to the surgical instrument. RESULTS: Local view selection for a solo surgery was performed without releasing the instrument. The accuracy of camera pose estimation was not significantly different between camera resolutions, but it was significantly different between background camera images with different numbers of features (P < 0.01). The success rate of ROI selection diminished as the number of separated regions increased. However, separated regions up to 12 with a region size of 160 × 160 pixels were selected with no failure. Surgical tasks on a phantom model and a cadaver were attempted to verify the feasibility in a clinical environment. CONCLUSIONS: Hands-free endoscope manipulation without releasing the instruments in hand was achieved. The proposed method requires only a small, low-cost camera and an image processing. The technique enables surgeons to perform solo surgeries without a camera assistant.

Arterial Stiffness and Cardiovascular Autonomic Dysfunction in Patients with Parkinson's Disease.

BACKGROUND: Pulse wave velocity is a marker of arterial stiffness and a surrogate marker of vascular damage. Autonomic abnormalities associated with blood pressure are relatively commonly observed in patients with Parkinson's disease (PD). OBJECTIVE: The purpose of this study was to compare arterial stiffness between patients with PD and controls and investigate the associations between cardiovascular autonomic dysfunction and pulse wave velocity in PD. METHODS: One hundred twenty-five PD patients without diabetes mellitus were enrolled into this study, along with 22 age-matched controls. Orthostatic vital signs and ambulatory 24-hour blood pressure monitoring values were recorded. Pulse wave velocity was used to evaluate arterial stiffness. RESULTS: In PD, greater arterial stiffness was associated with orthostatic hypotension, supine hypertension, nocturnal hypertension, and nondipping. Dopaminergic treatment did not influence cardiovascular autonomic dysfunction or arterial stiffness. Although pulse wave velocity was mildly increased in patients with PD compared to controls, the arterial stiffness in PD patients without autonomic failure was similar to that in normal controls. Stiffer arteries were found only in patients with PD and autonomic failure. CONCLUSION: These findings suggest that cardiovascular autonomic dysfunction is associated with arterial stiffness in PD. PD itself does not affect arterial stiffness, whereas autonomic blood pressure disturbances influence alterations in arterial stiffness and architectural changes in the arteries of PD patients.