Cloud-based Network Virtualization in IoT with OpenStack

In Cloud computing deployments, specifically in the Infrastructure-as-a-Service (IaaS) model, networking is one of the core enabling facilities provided for the users. The IaaS approach ensures significant flexibility and manageability, since the networking resources and topologies are entirely under users’ control. In this context, considerable efforts have been devoted to promoting the Cloud paradigm as a suitable solution for managing IoT environments. Deep and genuine integration between the two ecosystems, Cloud and IoT, may only be attainable at the IaaS level. In light of extending the IoT domain capabilities’ with Cloud-based mechanisms akin to the IaaS Cloud model, network virtualization is a fundamental enabler of infrastructure-oriented IoT deployments. Indeed, an IoT deployment without networking resilience and adaptability makes it unsuitable to meet user-level demands and services’ requirements. Such a limitation makes the IoT-based services adopted in very specific and statically defined scenarios, thus leading to limited plurality and diversity of use cases. This article presents a Cloud-based approach for network virtualization in an IoT context using the de-facto standard IaaS middleware, OpenStack, and its networking subsystem, Neutron. OpenStack is being extended to enable the instantiation of virtual/overlay networks between Cloud-based instances (e.g., virtual machines, containers, and bare metal servers) and/or geographically distributed IoT nodes deployed at the network edge.

Imaging Luminescence Thermometry to 750 °C for the Heat Treatment of Common Engineering Alloys and Comparison with Thermal Imaging

Accurate temperature measurements are critical in manufacturing, affecting both product quality and energy consumption. At elevated temperatures, non-contact thermometers are often the only option. However, such instruments require prior knowledge of the surface emissivity, which is often unknown or difficult to determine, leading to large errors. Here we present a novel imaging luminescence thermometer based on the intensity ratio technique using magnesium fluorogermanate phosphor, with the potential to overcome this limitation. We describe measurements performed on a number of engineering alloys undergoing heat treatment at temperatures of up to 750 °C and compare these measurements against a traditional contact thermocouple and thermal imager system. Agreement between the luminescence and embedded thermocouple temperatures was found to be better than 45 °C at all temperatures. However, the thermal imager measurement on the bare metal samples, with the instrument emissivity set to 1.0, showed differences of up to 500 °C at 750 °C, a factor of 10 larger. In an effort to improve the thermal imager accuracy, its instrument emissivity was adjusted until its temperature agreed with that of the thermocouple. When measuring on the bare metal, the effective emissivity was strongly sample dependent, with mean values ranging from 0.205 to 0.784. Since the phosphor derived temperatures exhibited substantially smaller errors compared to the thermal imager, it is suggested that this method can be used to compliment the thermal imaging technique, by providing a robust mechanism for adjustment of the instrument emissivity until agreement between the thermal imager and phosphor thermometer is obtained.

A Single-Center Study on the Outcomes of Target Limb Revascularization in Femoropopliteal Lesions Treated With Drug Coated Balloons and Bare Metal Stents

Purpose: Multiple randomized controlled trials have shown that both drug coated balloons (DCBs) and bare metal stents (BMSs) significantly reduce restenosis in femoropopliteal lesions compared with plain balloon angioplasty. However, few studies have directly compared DCB and BMS treatments. Therefore, the goal of our study was to determine if the rate of target lesion revascularization (TLR) differs between DCB and BMS treatment at our center. Materials and methods: We performed a retrospective chart review of femoropopliteal interventions at a single center from 2009 to 2017. The intervention, patient and lesion characteristics, and TLR events were recorded. Exclusion criteria were loss of follow-up, death, bail-out stenting, and amputation within 60 days of treatment. Freedom from TLR was analyzed over a 3 year period with Kaplan-Meier survival curves. Cox hazard ratios were calculated to account for patient and lesion characteristics. Results: A total of 322 lesions (234 patients) treated with DCBs and 225 lesions (194 patients) treated with BMSs were included in this study. There were significant differences in baseline patient and lesion characteristics between groups—a greater proportion of women, patients with dyslipidemia, and lesions with popliteal involvement were treated with DCBs. There was no difference in the freedom from TLR between DCBs and BMSs. Accounting for patient and lesion characteristics, there was still no difference between DCBs and BMSs on the hazard of TLR. While our analysis did not detect a difference in the rate of TLR, there was a significant difference in the type of TLR. Compared with DCBs, a greater proportion of lesions initially treated with BMSs were retreated via surgical bypass rather than endovascular intervention, suggesting that lesions treated with DCBs may be more amenable to future endovascular intervention. Conclusion: Our retrospective analysis showed no difference in the rate of TLR between lesions treated with DCBs and BMSs. However, DCBs were more often used in complicated lesions involving popliteal arteries and may also allow for easier endovascular reintervention.

Correction: Blood compatibility of a new zwitterionic bare metal stent with hyperbranched polymer brushes

Correction for ‘Blood compatibility of a new zwitterionic bare metal stent with hyperbranched polymer brushes’ by Xiaobo Wang et al., J. Mater. Chem. B, 2013, 1, 5036–5044, DOI: 10.1039/C3TB20855A.

Zenith AAA endovascular graft suprarenal bare metal stent separation with graft migration and type IA endoleak

Background The Zenith endovascular graft (Cook Medical, Bloomington, IN, USA) is a well-recognised device used in endovascular repair of abdominal aortic aneurysms (EVAR). After a small number of reported cases of suprarenal stent separation from the main body of the graft, modifications were made to the strength and durability of the suture line attachment of the proximal bare metal component prior to release in 2003. This report describes a further case of suprarenal stent separation and type IA endoleak in a patient who underwent an EVAR using the Zenith device in 2012. Methods We present a case report of a 77-year-old male with incidental finding of type IA endoleak on a background of elective endovascular repair for 50.4-mm infrarenal abdominal aortic aneurysm (AAA), with a Cook Zenith endograft. Computed tomography (CT) demonstrated separation of the suprarenal bare metal stent from the main body of the endograft, with resultant graft migration and increase in native aneurysm sac size. Results The patient underwent semi-urgent surgery with successful placement of a bridging thoracic stent graft between the lowest renal artery and main body of the pre-existing graft. Conclusions This case report describes a rare complication of Zenith devices, additionally emphasising the importance of regular surveillance imaging following EVAR.

Advanced virtual prototyping for cyber-physical systems using RISC-V: implementation, verification and challenges

Virtual prototypes (VPs) are crucial in today’s design flow. VPs are predominantly created in SystemC transaction-level modeling (TLM) and are leveraged for early software development and other system-level use cases. Recently, virtual prototyping has been introduced for the emerging RISC-V instruction set architecture (ISA) and become an important piece of the growing RISC-V ecosystem. In this paper, we present enhanced virtual prototyping solutions tailored for RISC-V. The foundation is an advanced open source RISC-V VP implemented in SystemC TLM and designed as a configurable and extensible platform. It scales from small bare-metal systems to large multi-core systems that run applications on top of the Linux operating system. Based on the RISC-V VP, this paper also discusses advanced VP-based verification approaches and open challenges. In combination, we provide for the first time an integrated and unified overview and perspective on advanced virtual prototyping for RISC-V.

Drug-eluting versus bare metal stents in saphenous vein grafts compared to native coronary vessels. The NORSTENT study.

Background. Drug-eluting stents (DES) reduce target lesion revascularization (TLR) with no effect on mortality or myocardial infarction (MI) compared to bare metal stents (BMS) in native vessels. Randomized stent studies in saphenous vein grafts (SVG) are few and the reported effects are ambiguous. The NORSTENT study is the first to randomize lesions to percutaneous coronary intervention (PCI) in native vessels and SVG. Aims. To compare rate of mortality, MI and TLR across stent and vessel types. Methods. In this substudy 6087 patients with a single lesion in native vessels and 164 in SVG, were followed for 5 years. Results. MI was more frequent in SVG (subdistributional hazard ratio (SHR) 4.95 (3.75 – 6.54, p<0.001), but not affected by stent type. In the first 500 days DES reduced TLR in native vessels (SHR 0.21 ( 0.15 – 0.30)p<0.001) and SVG (SHR 0.18 (0.04 – 0.80) p=0.02). Thereafter DES and BMS were equivalent in native vessels, but DES had a higher TLR rate than BMS in SVG (SHR 3.31 (1.23 – 8.94) p=0.02). After 5 years the TLR rate was still significantly lower for DES in native vessels (3.2 % versus 7.8 %, p<0.001) but not in SVG (21.4 % vs 18. 4%). Conclusion: In SVG no difference in TLR between DES and BMS was observed after 5 years in contrast to persistent benefit in native vessels. The high rate of TLR and myocardial infarction in SVG makes treatment of native vessels a preference whenever feasible and better treatment options for SVG are warranted.