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In this paper, we put forward the model of multiple linear-combination security multicast network coding, where the wiretapper desires to obtain some information about a predefined set of multiple linear combinations of the source symbols by eavesdropping any one (but not more than one) channel subset up to a certain size r , referred to as the security level . For this model, the security capacity is defined as the maximum average number of source symbols that can be securely multicast to all sink nodes for one use of the network under the linear-combination security constraint. For any security level and any linear-combination security constraint, we fully characterize the security capacity in terms of the ratio of the rank of the linear-combination security constraint to the number of source symbols. Also, we develop a general construction of linear security network codes. Finally, we investigate the asymptotic behavior of the security capacity for a sequence of linear-combination security models and discuss the asymptotic optimality of our code construction.

Internet of Things (IoT) connects billions of everyday objects to the Internet. The mobility of devices can be facilitated by means of employing multiple wireless links. However, packet loss is a common phenomenon in wireless communications, where the traditional forwarding strategy undergoes severe performance issues in a multi-hop wireless network. One solution is to apply batched sparse (BATS) codes. A fundamental difference from the traditional strategy is that BATS codes require the intermediate network nodes to perform recoding, which generates recoded packets by network coding operations. Literature showed that advanced recoding schemes and burst packet loss can enhance and diminish the performance of BATS codes respectively. However, the existing protocols for BATS codes cannot handle both of them at the same time. In this paper, we propose a paradigm of protocol design for BATS codes. Our design can be applied in different layers of the network stack and it is compatible to the existing network infrastructures. The modular nature of the protocol can support different recoding techniques and different ways to handle burst packet loss. We also give some examples to demonstrate how to use the protocol.

The study on close-quarter manoeuvring of vessels is of great importance for the safety and efficiency of maritime operations. In this paper, the hydrodynamic interactions between two vessels in moderate-speed overtaking manoeuvres are studied. Computational investigation by free-surface panel method is performed, and the results are assessed against experimental measurements from towing-tank model tests. The influences of overtaking speed and the speed difference between vessels on the hydrodynamic loads are studied. It is found that the free-surface deformation, on account of the blockage effects of the bodies, wave-making properties of the vessels, and the interference of unsteady wave patterns between the vessels, considerably affects the hydrodynamic interactions. In addition, it is also discovered that the influence from the unsteady heave and pitch motions of the hulls on the hydrodynamic loads can be non-negligible. Furthermore, it is found that the slower vessel to be overtaken generally experiences larger loads with more variation than the overtaking vessel. The loads on both vessels become more similar to those of a steady-state di-hull system when the speed difference between vessels is small., Competing Interests: We have no competing interests with anyone.

Acute ischaemic stroke due to large vessel occlusion leads to grave neurological morbidity and mortality. Conventional intravenous thrombolysis is ineffective in achieving timely reperfusion in this group of patients. The publication of five positive randomised controlled trials of emergency thrombectomy for acute ischaemic stroke in 2015 provided strong evidence to support endovascular reperfusion therapy and represented a paradigm shift in acute stroke management. In this article, we review the current evidence and international guidelines, and report on the findings of a survey study of the clinical practice and opinions of local neurologists, neurosurgeons, and interventional radiologists in emergency thrombectomy. We also discuss the controversies around thrombectomy treatment, local experience, and suggestions to incorporate thrombectomy in acute stroke treatment.

Background: This study evaluated the effectiveness of 400 mg ibuprofen arginate either as a pre-emptive (PRE group) or postoperative (POST group) analgesic using a common dental pain model., Methods: A randomized double-blind crossover clinical trial involving a series of consecutive patients admitted for bilateral third molar surgery. Results were analysed according to the self-reported pain score and the pattern of rescue medication taken., Results: The mean pain score ranged from 0.73 to 1.60 for the PRE group and 0.47 to 1.41 for the POST group among 30 included subjects. The mean time point when first rescue medication taken was 7.3 hours and 8.3 hours postoperative, respectively. Nine patients (30 per cent) in the PRE group and 12 patients (40 per cent) in the POST group took no rescue medication. There was no statistically significant difference for all parameters between groups, while a majority (53 per cent) found the drug "good" to "excellent" in both groups., Conclusions: Ibuprofen arginate may be considered effective in reducing surgically induced moderate to severe pain when administered either pre-operatively or postoperatively due to the reported relatively low pain score, less consumption of rescue medication, delayed onset of pain, good number of pain-free patients and a high rating in the global assessment score.

The study investigated the experience of depressive symptoms and the relationship with diffuse physical symptoms reporting in southern Chinese seeking professional care for temporomandibular disorders (TMD) in Hong Kong. Eighty-seven new patients [77 females/10 males; mean age 39.3 years (SD 12.7)] referred to the specialist TMD clinic at the Prince Philip Dental Hospital, Hong Kong participated in this study. The Research Diagnostic Criteria (RDC)/TMD history questionnaire was used to derive Axis II psychological data. Psychological status was assessed through depression and non-specific physical symptoms (NPS) scores (pain items included and excluded) measured with RDC/TMD Axis II instruments; 42.5% of patients experienced moderate/severe depression symptoms; 59.8% and 57.5% had moderate/severe NPS scores when pain items were included and excluded, respectively. Strong, positive and statistically significant correlations were noted between depression scores and the NPS scores that included pain items (r = 0.80) and those that did not (r = 0.80). The correlations remained consistent and were of similar magnitude when male patients were excluded from the computation and also when the possible effect of patient age was controlled. While taking into account the modest patient sample which was related to a low rate of treatment seeking, depressive symptoms were common and similar to other western and Chinese patient groups. NPS reports were higher than in Singapore Chinese patients. There appeared to be a clear association between depression and diffuse physical symptoms. The findings should be considered in the holistic care of Chinese people with TMD.

The study aimed to assess the distribution of temporomandibular disorders (TMD) sub-types, psychological distress and psychosocial dysfunction in southern Chinese people seeking treatment for TMD using Research Diagnostic Criteria for TMD (RDC/TMD) and investigate potential cross-cultural differences in sub-type prevalence and psychosocial impact. Eighty-seven consecutive patients (77 females; 10 males) with a mean age of 39.3 years (s.d. 12.8) newly referred to the specialist TMD clinic at the Prince Philip Dental Hospital, Hong Kong over a 20-month period took part in the study. RDC/TMD history questionnaire and clinical assessment data were used to derive Axis I and II findings. Group I muscle disorders were the most common and found in 57.5% of patients. Group II (disc displacement) disorders were found in 42.5% and 47.1% of the right and left temporomandibular joints (TMJ) respectively. Group III disorders (arthralgia/arthrosis/arthritis) were revealed in 19.5% and 23.0% of right and left TMJ's respectively. In the Axis II assessment, 42.5% of patients had moderate/severe depression scores, 59.7% had moderate/severe somatization scores and based on graded chronic pain scores 15.0% had psychosocial dysfunction (grade III and IV). While acknowledging the small sample size, the distribution of RDC/TMD Axis I and II diagnoses was fairly similar in Chinese TMD patients compared with Western and other Asian patient groups. However, in Chinese patients, myofascial pain with limited jaw opening and TMJ disc displacement with reduction were more common and a significant number experienced psychological distress and psychosocial dysfunction. The findings have implications for the management of TMD in Chinese people.

Purpose: To describe a method for stereomodel-assisted fibula flap harvest and mandibular reconstruction utilizing multiple fibula bony segments., Materials and Methods: Stereomodels of the mandible and the fibula were obtained from computed tomography scan data. The length of fibula to be harvested was predetermined by measurement of the stimulated of existing mandibular defect on the mandibular stereomodel. A titanium reconstruction plate was shaped to fit the original mandibular contour. The stereomodel fibula was divided into multiple segments and the segments were placed on the mandibular stereomodel in the ideal edentulous position against the upper dentition and simulate the angular contour of the mandible for best comesis. The predetermined bony segments were measured and the system was then transferred to the patient in the operation theater using acrylic locating splints., Results: Experience with 8 patients (2 primary and 2 secondary reconstructions) indicated that a good clinical outcome in terms of mandibular contour and positions of the reconstructed segment was possible. The outer facial appearance and symmetry were consistently excellent and no instability or malposition of the graft segments was encountered., Conclusion: Stereomodel-assisted fibula flap harvest and insertion is a worthwhile attempt at improving the results of mandibular reconstruction and deserves further attention.

Purpose: To establish a protocol for image-guided minimally invasive surgical access to the temporomandibular joint (TMJ)., Materials and Methods: This study involved 2 patients with TMJ pain and mandibular motion dysfunction. Axial magnetic resonance imaging (MRI) of the TMJ was obtained and loaded into an intra-operative navigation system to guide joint space injection. With a navigated syringe, 1 mL synvisc Hylan G-F 20 was directly injected into the superior and inferior joint spaces under navigation guidance., Results: With the assistance of an intraoperative navigational system, the TMJ MRI images were visualized in 3 dimensions and enabled guiding a needle into the superior and inferior joint spaces for therapeutic injection. The treatment outcome for both patients was satisfactory with improvement in pain score and mandibular motion., Conclusions: A protocol for image-guided minimally invasive surgical access to the TMJ was established. This could provide the technical basis for evaluation of accurate joint space intervention as a form of treatment of appropriate TMJ disorders.

In a patient with temporomandibular disorder who does not respond to conservative treatment, treatment with intra-articular injection of high molecular weight sodium hyaluronate can be suggested. In our study, 27 patients with nonreduced disc displacement were diagnosed clinically and confirmed by magnetic resonance imaging. The age range was from 21 to 63 years old, with a mean of 39.3 years. Two cycles of injection of high molecular weight sodium hyaluronate was performed on alternative weeks. Pain intensity was measured by the visual analog scale. Maximal mouth opening, clicking joint noise, and lateral movement were measured before and after injection for more than 6 months. Reduction of pain intensity and improvement in the maximum mouth opening parameter was statistically significant. In conclusion, this intra-articular injection using high molecular weight sodium hyaluronate looks very positive for patients affected by nonreduced disc displacement and is encouraged to be used as a primary treatment of temporomandibular joint dysfunction.

Elevation of the sinus floor to augment the alveolar process to place implants is an effective treatment. The traditional use of autologous bone implies a secondary donor site and the related morbidity, and, hence, is not readily accepted by many patients. The new graft material, synthetic peptide enhanced hydroxyapatite (PepGen P-15 Flow, Ceramed Dental, Lakewood, CO, DENTSPLY Int.,York, PA), shows the ease in use and ability to generate new bone growth in the sinus elevation procedure. Histologic and electromicroscopic analysis was performed on the new bone formed after the application.

Purpose: Positron emission tomography-computed tomography (PET-CT) is a new imaging modality that provides simultaneous functional and anatomic information. Its application in head and neck oncology is still evolving., Materials and Methods: Five illustrative cases who were scanned with this technique are presented., Results: The clinical application and impact on clinical management are described and discussed., Conclusion: Our experience indicates that PET-CT will assume a more important role than either CT, magnetic resonance imaging, or PET alone in head and neck cancer imaging.

Aim: The aim of this study was to determine the computed tomography (CT) presentation of odontogenic myxoma (OM) in a Chinese population and to compare them with those observed on the accompanying conventional radiographs (CR)., Materials and Methods: The files of the Department of Oral and Maxillofacial Surgery of the University of Hong Kong between 1989 and 2000 were reviewed for myxoma cases., Results: Ten cases of OM were found of which eight had been investigated by CT. The formatted hard copy was found in seven cases, four in the maxilla and three in the mandible. Most of the OMs had a round shape but one was fusiform. CT was more likely to display a cortex and its perforation. All OMs had perforated cortices on CT with soft tissue appearing outside the bony contour in two cases. Contrast enhancement was apparent in six cases. Both CR and CT displayed septae, but the latter method revealed that most septae were situated at the periphery, presenting as "sunray" type spicules in one case. Tooth displacement and root resorption were more reliably observed on CR., Conclusion: The likelihood of perforation and pattern of septa of OM is better displayed by CT. CR should also allow a better assessment of the degree of definition of the lesion's margins with adjacent normal bone. Therefore, both CT and CR should be used in an investigation of an OM.

Complex maxillofacial malformations continue to present challenges in analysis and correction beyond modern technology. The purpose of this paper is to present a virtual-reality workbench for surgeons to perform virtual orthognathic surgical planning and soft-tissue prediction in three dimensions. A resulting surgical planning system, i.e., three-dimensional virtual-reality surgical-planning and soft-tissue prediction for orthognathic surgery, consists of four major stages: computed tomography (CT) data post-processing and reconstruction, three-dimensional (3-D) color facial soft-tissue model generation, virtual surgical planning and simulation, soft-tissue-change preoperative prediction. The surgical planning and simulation are based on a 3-D CT reconstructed bone model, whereas the soft-tissue prediction is based on color texture-mapped and individualized facial soft-tissue model. Our approach is able to provide a quantitative osteotomy-simulated bone model and prediction of postoperative appearance with photorealistic quality. The prediction appearance can be visualized from any arbitrary viewing point using a low-cost personal-computer-based system. This cost-effective solution can be easily adopted in any hospital for daily use.

A new integrated computer system, the 3-dimensional (3D) virtual reality surgical planning and simulation workbench for orthognathic surgery (VRSP), is presented. Five major functions are implemented in this system: post-processing and reconstruction of computed tomographic (CT) data, transformation of 3D unique coordinate system geometry, generation of 3D color facial soft tissue models, virtual surgical planning and simulation, and presurgical prediction of soft tissue changes. The basic mensuration functions, such as linear and spatial measurements, are also included. The surgical planning and simulation are based on 3D CT reconstructions, whereas soft tissue prediction is based on an individualized, texture-mapped, color facial soft tissue model. The surgeon "enters" the virtual operatory with virtual reality equipment, "holds" a virtual scalpel, and "operates" on a virtual patient to accomplish actual surgical planning, simulation of the surgical procedure, and prediction of soft tissue changes before surgery. As a final result, a quantitative osteotomy-simulated bone model and predicted color facial model with photorealistic quality can be visualized from any arbitrary viewing point in a personal computer system. This system can be installed in any hospital for daily use.

The purpose of this paper is to report a new technique for three-dimensional facial soft-tissue-change prediction after simulated orthognathic surgical planning. A scheme for soft tissue deformation, "Computer-assisted three-dimensional virtual reality soft tissue planning and prediction for orthognathic surgery (CASP)", is presented. The surgical planning was based on three-dimensional reconstructed CT visualization. Soft tissue changes were predicted by two newly devised algorithms: Surface Normal-based Model Deformation Algorithm and Ray Projection-based Model Deformation Algorithm. A three-dimensional color facial texture-mapping technique was also used for generating the color photo-realistic facial model. As a final result, a predicted and simulated patient's color facial model can be visualized from arbitrary viewing points.

A scheme for texture mapping a 3D individualized color photo-realistic facial model from real color portraits and CT data is described. First, 3D CT images including both soft and hard tissues should be reconstructed from sequential CT slices, using a surface rendering technique. Facial features are extracted from 3D soft tissue. A generic mesh is individualized by correspondence matching and interpolation from those feature vertices. Three digitized color portraits with the "third" dimension from reconstructed soft tissue are blended and texture-mapped onto the 3D head model (mesh). A color simulated human head generated from frontal, right and left real color portraits can be viewed from an arbitrary angle in an inexpensive and user-friendly conventional personal computer. This scheme is the basic procedure in 3D computer-assisted simulation surgery.

A computer-assisted three-dimensional virtual osteotomy system for orthognathic surgery (CAVOS) is presented. The virtual reality workbench is used for surgical planning. The surgeon immerses in a virtual reality environment with stereo eyewear, holds a virtual "scalpel" (3D Mouse) and operates on a "real" patient (3D visualization) to obtain pre-surgical prediction (3D bony segment movements). Virtual surgery on a computer-generated 3D head model is simulated and can be visualized from any arbitrary viewing point in a personal computer system.

A rare presentation of Trichinella spiralis with squamous cell carcinoma of the tongue is reported. The possible carcinogenic potential of trichinosis and its management are discussed.