Generating Information-Diverse Microwave Speckle Patterns Inside a Room at a Single Frequency With a Dynamic Metasurface Aperture

We demonstrate that dynamic metasurface apertures (DMAs) are capable of generating a multitude of highly uncorrelated speckle patterns in a typical residential environment at a single frequency. We use a DMA implemented as an electrically-large cavity excited by a single port and loaded with many individually-addressable tunable metamaterial radiators. We placed such a DMA in one corner of a plywood-walled L-shape room transmitting microwave signals at 19 GHz as we changed the tuning states of the metamaterial radiators. In another corner, in the non-line-of-sight of the DMA, we conducted a scan of the field generated by the DMA. For comparison, we also performed a similar test where the DMA was replaced by a simple dipole antenna with fixed pattern but generating a signal that spanned 19-24 GHz. Using singular value decomposition of the scanned data, we demonstrate that the DMA can generate a multitude of highly uncorrelated speckle patterns at a single frequency. In contrast, a dipole antenna with a fixed pattern can only generate such a highly uncorrelated set of patterns when operating over a large bandwidth. The experimental results of this paper suggest that DMAs can be used to capture a diversity of information at a single frequency which can be used for single frequency computational imaging systems, NLOS motion detection, gesture recognition systems, and more

Experimental Synthetic Aperture Radar with Dynamic Metasurfaces

We investigate the use of a dynamic metasurface as the transmitting antenna for a synthetic aperture radar (SAR) imaging system. The dynamic metasurface consists of a one-dimensional microstrip waveguide with complementary electric resonator (cELC) elements patterned into the upper conductor. Integrated into each of the cELCs are two diodes that can be used to shift each cELC resonance out of band with an applied voltage. The aperture is designed to operate at K band frequencies (17.5 to 20.3 GHz), with a bandwidth of 2.8 GHz. We experimentally demonstrate imaging with a fabricated metasurface aperture using existing SAR modalities, showing image quality comparable to traditional antennas. The agility of this aperture allows it to operate in spotlight and stripmap SAR modes, as well as in a third modality inspired by computational imaging strategies. We describe its operation in detail, demonstrate high-quality imaging in both 2D and 3D, and examine various trade-offs governing the integration of dynamic metasurfaces in future SAR imaging platforms

Propofol-alfentanil vs propofol-remifentanil for posterior spinal fusion including wake-up test

Background. Wake-up test can be used during posterior spinal fusion (PSF) to ensure that spinal function remains intact. This study aims at assessing the characteristics of the wake-up test during propofol-alfentanil (PA) vs propofol-remifentanil (PR) infusions for PSF surgery. Methods. Sixty patients with scoliosis and candidates for PSF surgery were randomly allocated in either alfentanil (PA) or remifentanil (PR) group. After an i.v. bolus of alfentanil 30 μg kg-1 in the PA group or remifentanil 1 μg kg-1 in the PR group, anaesthesia was induced with thiopental and atracurium. During maintenance, opioid infusion consisted of alfentanil 1 μg kg-1 min-1 or remifentanil 0.2 μg kg-1 min-1, in the PA group and the PR group, respectively. All patients received propofol 50 μg kg-1 min-1. Atracurium was given to maintain the required surgical relaxation. At the surgeon's request, all infusions were discontinued. Patients were asked to move their hands and feet. Time from anaesthetic discontinuation to spontaneous ventilation (T1), and from then until movement of the hands and feet (T2), and its quality were recorded. Results. The average T1 and T2 were significantly shorter in the PR group 3.6 (2.5) and 4.1 (2) min than the PA group 6.1 (4) and 7.5 (4.5) min. Quality of wake-up test, however, did not show significant difference between the two groups studied. Conclusion. Wake-up test can be conducted faster with remifentanil compared with alfentanil infusion during PSF surgery. © 2006 Oxford University Press

Digestive enzymes activity and growth indices of rainbow trout (Oncorhynchus mykiss) fed diets supplemented with silymarin and Nickle Oxide nanoparticles

There is growing concern regarding nano-sized material discharge into water bodies and their subsequent toxicity to aquatic lives owing to increasingly rapid development and industrial applications of nanoparticles. This study evaluates the oral prescription of silymarin and Nickel Oxide nanoparticles in rainbow trout with an emphasis on growth indices and digestive enzymes activity. To that end, 1200 fish (3.83±0.01g) were randomly allotted into 8 distinct treatments including control group without any supplemental dietary Nickel Oxide nanopartcles or silymarin and the remaining seven experimental groups comprised of different combinations of Nickel Oxide nanoparticles (0, 100 and 500 mg /kg feed) and silymarin (0 and 1 g /kg feed) in the first and second month of the trial. All treatments were carried out in trplicate and the experiment lasted for 60 days. Results showed that the highest amylase activity was recorded in treatment 6 (16.56±1.00) (0 mg Nickel nanoparticle along with 1 g silymaryn - 500 mg Nickel nanoparticle and 1 g silymarin) which significantly differed from treatments 5 (0 mg Nickel Oxide nanoparticles and 1 mg silymarin-100 mg Nickel Oxide nanoparticles with 1 mg silymarin), 7 and 8 (fed diets containing 100 and 500 mg Nickel Oxide nanoparticles, respectively) (P≤0.05). The highest alkaline protease activity was observed in treatment 1 (0.54±0.05) (without any supplemental Nickel or silymarin), which was significantly different from those of treatments 7 and 8 (P≤0.05). The highest lipase activity was reported for treatment 4 (1.03±0.04) (500 mg Nickel nanoparticle with 1 g silymaryn- 0 mg nanoparticle and 1 g silymarin) which was significantly different from other treatments (P≤0.05). The results showed that simultaneous use of Nickel nanoparticle and silymarin in treatments 3, 4, 5 and 6 led to higher digestive enzymes activities in comparison to treatments 7 and 8. However, growth indices did not show any noticeable differences amongst studied treatments. It seems that in a long term exposure to Nickel Oxide nanoparticles and simoltanoues dietary silymarin inclusion, it would also be possible to observe differences in growth and nutritional indices, requiring further clarification

Efficacy of fentanyl transdermal patch in the treatment of chronic soft tissue cancer pain

Background: Cancer pain may be a major problem for health care providers worldwide. According to different studies reporting the pain severity, one-third of patients reported to have moderate to severe pain. Management of cancer pain is one of the most important goals of palliative care. Recently, different research results on the efficacy of opioid analgesics in chronic pain management have played a role to implement standards in pain control by government agencies worldwide. Objectives: This study aimed to investigate the efficacy of fentanyl transdermal patch in the treatment of chronic soft tissue cancer pain. Patients and Methods: In a prospective descriptive study, we evaluated 86 patients with soft tissue tumors with chronic pain referred to cancer institute of Imam Khomeini Hospital, Tehran, Iran, during 2006-2007. For all patients, transdermal fentanyl patch (25 μg/h) was administered. The appearance of patches was the same. Pain severity was measured by Visual Analogue Scale (VAS) initially and 24, 48 and 72 hours after the initiation of treatment. Results: Patients' characteristics and VAS score before the treatment were not significantly different (P > 0.05). According to our findings, the pain severity was significantly reduced after the treatment (P = 0.001). The incidence of adverse events in patients was significantly high (72). The most common adverse events were sleepiness, nausea and vomiting in 30.2 and 18.6, respectively. Conclusions: Transdermal fentanyl patch was an effective and safe method to reduce pain in patients with soft tissue tumors. Moreover, it could improve the quality of life in these patients, but adverse events occurred in approximately 72 of patients. © 2015, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM)