UAVNet: A Mobile Wireless Mesh Network Using Unmanned Aerial Vehicles

We developed UAVNet, a framework for the autonomous deployment of a flying Wireless Mesh Network using small quadrocopter-based Unmanned Aerial Vehicles (UAVs). The flying wireless mesh nodes are automatically interconnected to each other and building an IEEE 802.11s wireless mesh network. The implemented UAVNet prototype is able to autonomously interconnect two end systems by setting up an airborne relay, consisting of one or several flying wireless mesh nodes. The developed software includes basic functionality to control the UAVs and to setup, deploy, manage, and monitor a wireless mesh network. Our evaluations have shown that UAVNet can significantly improve network performance.

Evaluating the Trade-off Between Energy Efficiency and QoE in Wireless Mesh Networks

The increasing usage of wireless networks creates new challenges for wireless access providers. On the one hand, providers want to satisfy the user demands but on the other hand, they try to reduce the operational costs by decreasing the energy consumption. In this paper, we evaluate the trade-off between energy efficiency and quality of experience for a wireless mesh testbed. The results show that by intelligent service control, resources can be better utilized and energy can be saved by reducing the number of active network components. However, care has to be taken because the channel bandwidth varies in wireless networks. In the second part of the paper, we analyze the trade-off between energy efficiency and quality of experience at the end user. The results reveal that a provider's service control measures do not only reduce the operational costs of the network but also bring a second benefit: they help maximize the battery lifetime of the end-user device.

Initial clinical experience with the 4-F self-expanding XPERT stent system for infrapopliteal treatment of patients with severe claudication and critical limb ischemia

PURPOSE: To evaluate the primary success and short-term patency associated with a new 4-F sheath-compatible self-expanding nitinol stent after failed conventional angioplasty of distal popliteal and infrapopliteal lesions in severe lifestyle-limiting claudication (LLC) and chronic critical limb ischemia (CLI). MATERIALS AND METHODS: Between May 2003 and July 2005, 35 patients with Rutherford category 3-5 disease (16 patients with CLI, 19 patients with LLC) underwent percutaneous transluminal angioplasty (PTA) and stent implantation. Indications for stent placement were residual stenosis, flow-limiting dissections, or elastic recoil after PTA. Before and after the intervention and during the 6-month follow-up, clinical investigation, color-flow and duplex Doppler ultrasonography, and digital subtraction angiography were performed. Technical success, primary patency at 6 months, clinical improvement as defined by Rutherford with clinical and hemodynamic measures, and complications were evaluated. RESULTS: A total of 22 patients underwent distal popliteal artery stent placement and 13 underwent tibioperoneal artery stent placement. Stent implantation was successfully performed in all patients. After stent placement, the primary cumulative patency rate for the study group at 6 months was 82%. The mean resting ankle-brachial index at baseline was 0.50 +/- 0.16 and significantly increased to 0.90 +/- 0.17 at 12-24 hours after intervention and 0.82 +/- 0.24 at latest follow-up (P < .001 for both). The sustained clinical improvement rate was 80% at the 6-month follow-up. The 6-month limb salvage rate regarding major amputation was 100%. The rate of major complications was 17%. CONCLUSIONS: Infrapopliteal application of the new nitinol stent is a safe, feasible, and effective method with good short-term patency rate in the treatment of severe LLC and chronic CLI.

Percutaneous aortic valve replacement for severe aortic stenosis in high-risk patients using the second- and current third-generation self-expanding CoreValve prosthesis: device success and 30-day clinical outcome

OBJECTIVES: We sought to determine both the procedural performance and safety of percutaneous implantation of the second (21-French [F])- and third (18-F)-generation CoreValve aortic valve prosthesis (CoreValve Inc., Irvine, California). BACKGROUND: Percutaneous aortic valve replacement represents an emerging alternative therapy for high-risk and inoperable patients with severe symptomatic aortic valve stenosis. METHODS: Patients with: 1) symptomatic, severe aortic valve stenosis (area <1 cm2); 2) age > or =80 years with a logistic EuroSCORE > or =20% (21-F group) or age > or =75 years with a logistic EuroSCORE > or =15% (18-F group); or 3) age > or =65 years plus additional prespecified risk factors were included. Introduction of the 18-F device enabled the transition from a multidisciplinary approach involving general anesthesia, surgical cut-down, and cardiopulmonary bypass to a truly percutaneous approach under local anesthesia without hemodynamic support. RESULTS: A total of 86 patients (21-F, n = 50; 18-F, n = 36) with a mean valve area of 0.66 +/- 0.19 cm2 (21-F) and 0.54 +/- 0.15 cm2 (18-F), a mean age of 81.3 +/- 5.2 years (21-F) and 83.4 +/- 6.7 years (18-F), and a mean logistic EuroSCORE of 23.4 +/- 13.5% (21-F) and 19.1 +/- 11.1% (18-F) were recruited. Acute device success was 88%. Successful device implantation resulted in a marked reduction of aortic transvalvular gradients (mean pre 43.7 mm Hg vs. post 9.0 mm Hg, p < 0.001) with aortic regurgitation grade remaining unchanged. Acute procedural success rate was 74% (21-F: 78%; 18-F: 69%). Procedural mortality was 6%. Overall 30-day mortality rate was 12%; the combined rate of death, stroke, and myocardial infarction was 22%. CONCLUSIONS: Treatment of severe aortic valve stenosis in high-risk patients with percutaneous implantation of the CoreValve prosthesis is feasible and associated with a lower mortality rate than predicted by risk algorithms.

Primary reconstruction of open depressed skull fractures with titanium mesh

Open skull fractures have been traditionally managed in 2 stages: urgent craniotomy and elevation of the fracture with removal of contaminated bone, debridement, and delayed cranioplasty. Primary, single-stage repair of these injures has been said to entail risks such as infections. Recent experience, however, disproved these concerns.We used a primary single-stage reconstruction for patients presenting with open depressed skull fractures. All patients received antibiotic prophylaxis. The patients underwent elevation of the compound fracture and craniotomy if necessary. Debridement was performed, followed by skull reconstruction using a 0.6-mm titanium mesh.We present 5 consecutive male patients (age, 32.2 +/- 15.6 years) who underwent primary reconstruction of open depressed skull fractures. Clinical and radiologic follow-up was performed 2 months after surgery. The duration of the surgery was 2 +/- 1.6 hours. The size of the implanted mesh was 13 +/- 13.1 cm. No infection was detected in our series, with a follow-up period of 22 +/- 6.5 months (range, 16-29 months). The cosmetic result was defined in 4 patients as "excellent" and in 1 patient as "good."Primary reconstruction of open skull fractures with titanium mesh is feasible, safe, and cosmetically preferable than the conventional staged approach. The introduction into clinical practice can be warranted.

Evaluation of 15 mandibular reconstructions with Dumbach Titan Mesh-System and particulate cancellous bone and marrow harvested from bilateral posterior ilia

This study reports on 15 mandibular reconstructions using the Dumbach Titan Mesh-System and particulate cancellous bone and marrow harvested from bilateral posterior ilia. All cases showed segmental defects. Eleven cases involved patients with malignant tumor. Six patients had received irradiation of 40-50 Gy. Reconstructions were performed immediately in 1 patient and secondarily in the remaining 14 patients. In 13 cases, mandibles were successfully reconstructed. Of these 13 patients, 9 reconstructions were completed without complications, whereas the other 4 cases showed complications. In 2 cases, reconstruction failed completely. Overall success rate was 87%. Statistical analysis revealed the extent of mandibular defect, but not malignancy of the original disease or radiotherapy of mesh using a 3-dimensional skull model is expected to improve surgical outcomes.