Metal Stenting with or without Endobiliary Radiofrequency Ablation for Unresectable Extrahepatic Cholangiocarcinoma

Background: Retrospective comparison of stent patency and survival of patients with unresectable extrahepatic cholangiocarcinoma (CCA) treated by placement of self-expanding metal stents (SEMS) with or without endobiliary radiofrequency ablation (ERFA). Methods: Between January 2010 and September 2014, 76 patients with biliary obstruction caused by unresectable extrahepatic CCA (27 patients with Bismuth type I hilar CCA and 49 patients with distal CCA) were recruited into this study. Patients either received ERFA with SEMS (n = 34) or SEMS only (n = 42). Stent patency and survival of both groups were compared and predictors for overall survival were analyzed. Results: Demographic data were not different between the two groups. Complication rates of both groups were similar. Thirty-day stent patency was obtained in all patients and the median stent patency in the ERFA + SEMS group (9.5 months, 4.5 - 14.0 months) was significantly longer than that in the SEMS group (8.4 months, 4.9 - 11 months) (P = 0.024). The overall survival curve in the ERFA + SEMS group was significantly better than that of the SEMS group (P = 0.036). Multivariate Cox proportional hazards regression analyses showed that ERFA, tumor AJCC stage, extrahepatic CCA type, serum albumin and adjuvant chemotherapy were significant prognostic factors for overall patient survival. Conclusions: ERFA is effective for unresectable extrahepatic CCA and may improve metal stent patency and patient survival for unresectable extrahepatic CCA with biliary obstruction. Prospective randomized trials will be needed to confirm these findings.

Which is the Best PID Variant for Pneumatic Soft Robots?An Experimental Study

This paper presents an experimental study to compare the performance of model-free control strategies for pneumatic soft robots.Fabricated using soft materials,soft robots have gained much attention in academia and industry during recent years because of their inherent safety in human interaction.However,due to structural flexibility and compliance,mathematical models for these soft robots are nonlinear with an infinite degree of freedom(DOF).Therefore,accurate position(or orientation)control and optimization of their dynamic response remains a challenging task.Most existing soft robots currently employed in industrial and rehabilitation applications use model-free control algorithms such as PID.However,to the best of our knowledge,there has been no systematic study on the comparative performance of model-free control algorithms and their ability to optimize dynamic response,i.e.,reduce overshoot and settling time.In this paper,we present comparative performance of several variants of model-free PID-controllers based on extensive experimental results.Additionally,most of the existing work on modelfree control in pneumatic soft-robotic literature use manually tuned parameters,which is a time-consuming,labor-intensive task.We present a heuristic-based coordinate descent algorithm to tune the controller parameter automatically.We presented results for both manual tuning and automatic tuning using the Ziegler-Nichols method and proposed algorithm,respectively.We then used experimental results to statistically demonstrate that the presented automatic tuning algorithm results in high accuracy.The experiment results show that for soft robots,the PID-controller essentially reduces to the PI controller.This behavior was observed in both manual and automatic tuning experiments;we also discussed a rationale for removing the derivative term.

Percutaneous Microwave Coagulation for the Treatment of Small Solitary Focal Nodular Hyperplasia of Liver

Background: Whether percutaneous microwave coagulation (PMC) is safe and effective for the treatment of symptomatic focal nodular hyperplasia (FNH) of the liver remains unknown. Methods: Between January 2006 and September 2015, sixteen patients with solitary symptomatic FNHs in the liver (the largest diameter less than 5 cm) were treated by PMC. The safty and effectiveness were analyzed. Results: There were 4 males and 12 females. All these patients suffered from upper abdominal pain. The FNHs ranged in size from 3.2 cm to 5.0 cm (3.9 cm ± 0.12 cm). All the PMC procedures were performed successfully. All 16 patients had symptomatic improvement after the treatment with no procedure-related morbidity or mortality. Among 16 patients, 15 (93.8%) patients with FNHs were assessed to be ablated completely by CT examination performed within four weeks after PMC treatment. One patient failed to follow up regularly, but showed up 2 years and 7 months later for suffering upper abdominal pain again with original FNH enlargement, and the patient received surgical resection of the FNH and achieved asymptomatic aftermath. Conclusion: PMC is safe and effectiveness for symptomatic liver FNHs. PMC should be considered to be an alternative modality for those solitary FNHs with less than 5 cm in diameter.

SoftSSD:enabling rapid flash firmware prototyping for solid-state drives

Recently,solid-state drives(SSDs)have been used in a wide range of emerging data processing systems.Essentially,an SSD is a complex embedded system that involves both hardware and software design.For the latter,firmware modules such as the flash translation layer(FTL)orchestrate internal operations and flash management,and are crucial to the overall input/output performance of an SSD.Despite the rapid development of new SSD features in the market,the research of flash firmware has been mostly based on simulations due to the lack of a realistic and extensible SSD development platform.In this paper,we propose SoftSSD,a software-oriented SSD development platform for rapid flash firmware prototyping.The core of SoftSSD is a novel framework with an event-driven programming model.With the programming model,new FTL algorithms can be implemented and integrated into a full-featured flash firmware in a straightforward way.The resulting flash firmware can be deployed and evaluated on a hardware development board,which can be connected to a host system via peripheral component interconnect express and serve as a normal non-volatile memory express SSD.Different from existing hardware-oriented development platforms,SoftSSD implements the majority of SSD components(e.g.,host interface controller)in software,so that data flows and internal states that were once confined in the hardware can now be examined with a software debugger,providing the observability and extensibility that are critical to the rapid prototyping and research of flash firmware.We describe the programming model and hardware design of SoftSSD.We also perform experiments with real application workloads on a prototype board to demonstrate the performance and usefulness of SoftSSD,and release the open-source code of SoftSSD for public access.

Design and application of new storage systems

A storage system is the core of a computer,and plays an important role in the sustainable development of emerging strategic industries,such as artificial intelligence,big data,cloud computing,and the Internet of Things.Storage stack access is a major factor restricting the performance of data-intensive systems because of the increasing performance of processors and network devices.