Advances in Auxiliary Power Unit Development For Dual Supply UAVs

This paper address recent developments on auxiliary power unit for dual supply unmanned aerial vehicles. The proposed APU is designed and developed as a scalable backup power solution to tethered UAV systems. The APU addressed in this paper consist of off-line battery power supply and a high speed fault detection and switching unit, to control the proposed APU. Target operation of APU is to switch the battery power whenever the primary cable power is unavailable and switch back to cable power whenever the cable power is available during the UAV flight mission. The switching speed of newly developed prototype in this research with high speed logic ICs and n-channel MOSFETs is proved to be within milliseconds range and therefore could be considered fast enough for low altitude hovering missions. The outcome of the proposed design is also compact and light weighted, hence making the proposed prototype applicable in many existing battery powered UAVs for hybrid use

Orthogonal polarisation spectral imaging as a new tool for the assessment of antivascular tumour treatment in vivo: a validation study

Tumour angiogenesis plays a key role in tumour growth, formation of metastasis, detection and treatment of malignant tumours. Recent investigations provided increasing evidence that quantitative analysis of tumour angiogenesis is an indispensable prerequisite for developing novel treatment strategies such as anti-angiogenic and antivascular treatment options. Therefore, it was our aim to establish and validate a new and versatile imaging technique, that is orthogonal polarisation spectral™ imaging, allowing for non-invasive quantitative imaging of tumour angiogenesis in vivo. Experiments were performed in amelanotic melanoma A-MEL 3 implanted in a transparent dorsal skinfold chamber of the hamster. Starting at day 0 after tumour cell implantation, animals were treated daily with the anti-angiogenic compound SU5416 (25 mg kg bw−1) or vehicle (control) only. Functional vessel density, diameter of microvessels and red blood cell velocity were visualised by both orthogonal polarisation spectral™ imaging and fluorescence microscopy and analysed using a digital image system. The morphological and functional properties of the tumour microvasculature could be clearly identified by orthogonal polarisation spectral™ imaging. Data for functional vessel density correlated excellently with data obtained by fluroescence microscopy (y=0.99x+0.48, r2=0.97, RS=0.98, precision: 8.22 cm−1 and bias: −0.32 cm−1). Correlation parameters for diameter of microvessels and red blood cell velocity were similar (r2=0.97, RS=0.99 and r2=0.93, RS=0.94 for diameter of microvessels and red blood cell velocity, respectively). Treatment with SU5416 reduced tumour angiogenesis. At day 3 and 6 after tumour cell implantation, respectively, functional vessel density was 4.8±2.1 and 87.2±10.2 cm−1 compared to values of control animals of 66.6±10.1 and 147.4±13.2 cm−1, respectively. In addition to the inhibition of tumour angiogenesis, tumour growth and the development of metastasis was strongly reduced in SU5416 treated animals. This new approach enables non-invasive, repeated and quantitative assessment of tumour vascular network and the effects of antiangiogenic treatment on tumour vasculature in vivo. Thus, quantification of tumour angiogenesis can be used to more accurately classify and monitor tumour biologic characteristics, and to explore aggressiveness of tumours

Dynamic imaging of cancer growth and invasion: a modified skin-fold chamber model.

Contains fulltext : 70457.pdf (publisher's version ) (Closed access)The metastatic invasion of cancer cells from the primary lesion into the adjacent stroma is a key step in cancer progression, and is associated with poor outcome. The principles of cancer invasion have been experimentally addressed in various in vitro models; however, key steps and mechanisms in vivo remain unclear. Here, we establish a modified skin-fold chamber model for orthotopic implantation, growth and invasion of human HT-1080 fibrosarcoma cells, dynamically reconstructed by epifluorescence and multiphoton microscopy. This strategy allows repeated imaging of tumor growth, tumor-induced angiogenesis and invasion, as either individual cells, or collective strands and cell masses that move along collagen-rich extracellular matrix and coopt host tissue including striated muscle strands and lymph vessels. This modified window model will be suited to address mechanisms of cancer invasion and metastasis, and related experimental therapy