Gallbladder Removal Simulation for Laparoscopic Surgery Training: A Hybrid Modeling Method

Laparoscopic surgery has many advantages, but it is difficult for a surgeon to achieve the necessary surgical skills. Recently, virtual training simulations have been gaining interest because they can provide a safe and efficient learning environment for medical students and novice surgeons. In this paper, we present a hybrid modeling method for simulating gallbladder removal that uses both the boundary element method (BEM) and the finite element method (FEM). Each modeling method is applied according to the deformable properties of human organs: BEM for the liver and FEM for the gallbladder. Connective tissues between the liver and the gallbladder are also included in the surgical simulation. Deformations in the liver and the gallbladder models are transferred via connective tissue springs using a mass-spring method. Special effects and techniques are developed to achieve realistic simulations, and the software is integrated into a custom-designed haptic interface device. Various computer graphical techniques are also applied in the virtual gallbladder removal laparoscopic surgery training. The detailed techniques and the results of the simulations are described in this paper.     

Channel assignment with QoS guarantees for a multiclass multicode CDMA system

In a wireless system that supports multimedia services, each traffic requires different quality of service (QoS) at both communication on radio links and connection admission. We initially derive the uplink capacity satisfying the QoS constraint on radio links in a multiclass multicode code-division multiple-access (CDMA) system. Based on the derived capacity, the number of channel elements, which is one of the system resources, is determined. Then, we define the QoS parameters associated with connection processes. To guarantee the defined QoS at the connection level, under given channel elements, we propose a channel-assignment scheme with dynamic priority adjustment (DPA). The proposed scheme gives multipriority to different traffic classes. Real-time classes can preempt non-real-time classes with restricted preemptive priority. Such restriction is regulated by preemption-free code channels and a buffer threshold for non-real-time classes. Among real-time classes, different priorities are assigned to each traffic class by code reservation parameters. These multipriority parameters are dynamically adjusted in order to guarantee different QoS requirements. We analyze the DPA scheme by the matrix-geometric method, and evaluate the performance of each traffic class. The results show that the proposed scheme flexibly guarantees QoS depending on traffic loading condition and achieves high channel utilization.     

Orchestration in Distributed Web-of-Objects for Creation of User-Centered IoT Service Capability

Enhancing the service provisioning capability in IoT, it has been considered essential to support user-centric service feature. A semantic ontology model representing device, resource and service is proposed to make the knowledge based relationship to denote applications on WoO platform. Virtual object (VO) is introduced to represent a logical object in reference with physical thing including device profiles. The composite virtual object are formed with the combination of multiple VOs and the physical location and neutral things are defined as Non-ICT entities, they are also transformed into virtual object to provide much detailed information and services. The paper includes the implementation results obtained after evaluation of the developed testbed from the WoO platform with their performance.     

Assembly of strands of multiwall carbon nanotubes and gold nanoparticles using alkanedithiols

Multiwall carbon nanotubes and gold nanoparticles (MWCNT–AuNP) were assembled into strands by cross-linking with alkanedithiols. Long MWCNT strands were first shortened to ∼0.25 μm by chemical oxidation followed by ball-milling, and then thiolated by reaction with cysteamine. The thiol groups on the surfaces of the MWCNT strands combined with Au nanoparticles to produce MWCNT–AuNP strands. A simple mixing of these strands with alkanedithiols resulted in an assembly of strands linked by the alkanedithiols which adsorbed onto the surfaces of the AuNPs attached to the MWCNT–AuNP strands. Short MWCNT–AuNP strands connected to one another in a parallel arrangement, whereas long strands assembled in a crossing arrangement. The possibility of using this method to chemically bond MWCNTs to lower the contact resistance of thin CNT films is discussed.     

Effect of a compatibilizer on the structural development of a thermotropic liquid crystalline polymer/polystyrene blend

A fine fibril structure of a thermotropic liquid crystalline polymer (TLCP, a poly(ester amide)) can be developed in a shear flow field of a thermoplastic matrix (polystyrene, PS). Addition of a third component, a poly(styrene‐co‐maleic anhydride) (SMA), that interacts with the thermotropic liquid crystalline polymer facilitates the structural development of the TLCP phase by acting at the interface. Moreover, it brings about good adhesion at the interface and enables the dispersed liquid crystalline polymer phase to be deformed in shear flow without strong elongation even though the viscosity of the matrix is much lower than that of the liquid crystalline polymer. The mechanical properties were substantially improved because of both the good adhesion at the interface and fibril generation, which were ascribed to the SMA interaction. These results have important implications in that they provide a means to produce strong and tough in‐situ composites when the viscosity of the matrix polymer is lower than that of the dispersed liquid crystalline polymer which is immiscible with the matrix polymer. Morphological observations determined the significance of the third component (SMA) in immiscible polymer blends, and an optimum amount of SMA exists for best mechanical performance.     

A cross-linked poly(methyl methacrylate) gate dielectric by ion-beam irradiation for organic thin-film transistors

The electrical characteristics of pentacene organic thin-film transistors (OTFTs) using cross-linked poly(methyl methacrylate) (PMMA) as the gate dielectric are reported. Ultra-thin films of cross-linked PMMA could be obtained by spin-coating and subsequent irradiation using a 1.515 MeV ⁴He⁺ ion beam. The resulting film, with a thickness of 33 nm, possessed a low leakage current density of about 10^?6 A cm^?2 for fields up to 2 MV cm^?1. OTFTs incorporating the cross-linked dielectric operated at relatively low voltages, <10 V, and exhibited a mobility of 1.1 cm² V^?1 s^?1, a threshold voltage of ?1 V, a sub-threshold slope of 220 mV per decade and an on/off current ratio of 1.0 × 10⁶.     

Image subband coding using context-based classification andadaptive quantization

Adaptive compression methods have been a key component of many proposed subband (or wavelet) image coding techniques. This paper deals with a particular type of adaptive subband image coding where we focus on the image coder's ability to adjust itself "on the fly" to the spatially varying statistical nature of image contents. This backward adaptation is distinguished from more frequently used forward adaptation in that forward adaptation selects the best operating parameters from a predesigned set and thus uses considerable amount of side information in order for the encoder and the decoder to operate with the same parameters. Specifically, we present backward adaptive quantization using a new context-based classification technique which classifies each subband coefficient based on the surrounding quantized coefficients. We couple this classification with online parametric adaptation of the quantizer applied to each class. A simple uniform threshold quantizer is employed as the baseline quantizer for which adaptation is achieved. Our subband image coder based on the proposed adaptive classification quantization idea exhibits excellent rate-distortion performance, in particular at very low rates. For popular test images, it is comparable or superior to most of the state-of-the-art coders in the literature.     

Strain-Tolerant,High-Detectivity,and Intrinsically Stretchable All-Polymer Photodiodes

A skin-like photodiode (PD) that is stretchable and skin-conformable is crucial to opening the next-generation wearable electronics for optical biometric monitoring, biomedical imaging, and others. To achieve reliable PD characteristics under large deformation, stretchable PDs with high detectivity and high mechanical stretchability must be developed. Herein, intrinsically stretchable polymer-based PDs (is-PPDs) comprising all-polymeric constituent layers are demonstrated. In particular, elastomeric photoactive layers consisting of an elastomer with p-/n-type semiconducting polymers and conducting polymer-based stretchable transparent electrodes with modulated work functions improve both the mechanical stability and the detectivity (D*) of is-PPDs. Accordingly, is-PPDs show excellent D* over 10¹³ Jones with a suppressed dark current density of 0.1 nA cm⁻² before and after 100% stretching. The proposed is-PPDs record high-quality and stable photoplethysmography signals at the wrist with outward extension.