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An overview of liquid crystal technology for microwave and millimeter-wave frequencies is presented. The potential of liquid crystals as reconfigurable materials arises from their ability for continuous tuning with low power consumption, transparency, and possible integration with printed and flexible circuit technologies. This paper describes physical theory and fundamental electrical properties arising from the anisotropy of liquid crystals and overviews selected realized liquid crystal devices, throughout four main categories: resonators and filters, phase shifters and delay lines, antennas, and, finally, frequency-selective surfaces and metamaterials.

Fast probability integration (FPI) algorthms are adapted, extended and used to perform nuclear engineering uncertainty analyses. Methods are presented to improve the efficiency and precision of FPI for frequently encountered input distributions, to permit quick estimates of extreme model output quantiles and to provide appropriate sensitivity and uncertainty importance measures. Advantages and disadvantages of FPI as a stand-alone method are explored in two demonstration applications. FPI is first applied to estimate extreme (0.95, 0.99, 0.999 and 0.9999) quantiles of the frequency of a dominant station blackout accident. Sensitivity measures are quantified to indicate how the relative importance of each model input changes at progressively more extreme output quantiles. FPI is next applied to analyze uncertainties in fire damage times predicted by compbrn iiie . Alternative FPI-based uncertainty importance measures are compared and shown to consistently rank the input contributions to the output uncertainty. FPI results are compared with results obtained from Monte Carlo sampling to demonstrate the computational advantage that clearly favors FPI, especially at the more extreme output quantiles. In a third application, Latin hypercube sampling (LHS) is combined with FPI to determine extreme quantiles of peak cladding temperature during the blowdown phase of a large-break loss of coolant accident as modeled by trac-pfi/mod2 . The 0.95 quantile peak cladding temperature is reproducibly determined to within 2 K in one LHS-FPI iteration, which is based on only 21 trac-pfi/mod2 runs. To demonstrate convergence for a more extreme case, LHS-FPI is also applied to estimate the 0.999 quantile peak cladding temperature. In each LHS-FPI iteration a final code run is performed to assure that the code-calculated peak cladding temperature agrees with that predicted by LHS-FPI at the most probable point. Importance measures are quantified at this point to identify dominant input-output relationships. Compared with past code scaling, applicability and uncertainty (CSAU) analyses, LHS-FPI offers a significant reduction in the number of best-estimate code runs required while providing additional checks and insights.

The characterization of a tunable band-pass filter based on stepped-impedance resonator (SIR) is presented in this work. The designed filter uses a half-wavelength resonator patch above a multi-layer substrate, with liquid crystal as its central layer, making it continuously tunable at frequencies around S-band. Two liquid crystal samples are considered for three different approaches: lumped-element circuit simulation, full-wave electromagnetic simulations and prototype measurements. The results demonstrate the possibility of using a simple lumped-element circuit simulation for rapid calculation of the performances of liquid crystal devices at microwave frequencies.

Liquid crystals have potential applications in the design of tunable microwave devices. Polyimide films are commonly incorporated in designs to achieve reproducible molecule alignment in the unbiased state. In this investigation two separate resonator elements are designed and investigated: One is fabricated with polyimide layers and one without. Experimental results obtained with a patch resonator illustrate that about half of the maximum tuning range is achieved without polyimide layers. Since substrates able to sustain a temperature range of 180–300 °C are required for the polyimide film curing process, avoiding polyimide enables using even lower heat resistant substrates for various tunable microwave applications and can lead to faster fabrication processes.

Vitamin B₁₂ is found almost exclusively in animal-based foods and is therefore a nutrient of potential concern for those following a vegetarian or vegan diet. Vegans, and anyone who significantly limits intake of animal-based foods, require vitamin B₁₂-fortified foods or supplements. Vitamin B₁₂ deficiency has several stages and may be present even if a person does not have anaemia. Anyone following a vegan or vegetarian diet should have their vitamin B₁₂ status regularly assessed to identify a potential problem. A useful process for assessing vitamin B₁₂ status in clinical practice is the combination of taking a diet history, testing serum vitamin B₁₂ level and testing homocysteine, holotranscobalamin II or methylmalonic acid serum levels. Pregnant and lactating vegan or vegetarian women should ensure an adequate intake of vitamin B₁₂ to provide for their developing baby. In people who can absorb vitamin B₁₂, small amounts (in line with the recommended dietary intake) and frequent (daily) doses appear to be more effective than infrequent large doses, including intramuscular injections. Fortification of a wider range of foods products with vitamin B₁₂, particularly foods commonly consumed by vegetarians, is likely to be beneficial, and the feasibility of this should be explored by relevant food authorities.

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Defective hemostasis in haemophilia patients with FVIII inhibitors results in a dramatic decrease in thrombin generation forming unstable fibrin clots that are susceptible to fibrinolyisis. In this study we tested whether the combination of plasma derived activated prothrombin complex concentrate (pd-aPCC) with tranexamic acid (TXA) may improve fibrin clot stability in FVIII inhibitor plasma. A microplate assay for clot lysis time was used to assess clot stability in FVIII inhibitor plasma. The effect of pd-aPCC on clot stability was first tested using the commercial FVIII inhibitor plasma. TXA (5 ~ 10 mg mL⁻¹) increased clot lysis time, but pd-aPCC (0.25 ~ 1.0 U mL⁻¹) had no effect on it. The combination of pd-aPCC and TXA significantly increased clot lysis time compared with TXA alone. The effect appeared to be limited to fibrin clot resistance to fibrinolysis, as TXA was found to have no effect on thrombin generation induced by pd-aPCC. The effect of pd-aPCC and TXA on clot stability was then tested and verified in plasma samples from ten patients with severe haemophilia A and inhibitors. The combination of TXA (10 mg mL⁻¹) and pd-aPCC (0.5 U mL⁻¹) significantly increased clot lysis time compared to TXA alone. Our results suggest that the combination of pd-aPCC with TXA improves clot stability in FVIII inhibitor plasma without additional increases in thrombin generation.

Two 6 GHz microstrip patch antennas made from conducting polymers with relatively low DC conductivity such as PEDOT (10000 S/m) and PPy (2000 S/m) are presented. The performance of these patch antennas is compared with a similar copper patch antenna. The results indicate that it is possible to obtain reasonable performance albeit with modest radiation efficiencies. The PEDOT antenna achieved a maximum gain of 2.2 dB, while the PPy antenna reached a gain of 3.8 dB, as against 6.0 dB for a corresponding Cu patch antenna The results confirm the potential of polymer materials for microwave antennas and suggest that CPs may be of use in other passive microwave circuit applications.

Getsinger's Longitudinal Section Electric model describing the propagation characteristics of a single layer microstrip line is modified to cater for ‘n’ layers. An accurate closed-form expression for two and three layered structures is presented and validated against full-wave numerical results. The computed effective permittivity for a randomly selected two and three layer dielectric microstrip line is presented. In the selected examples, for the modified Getsinger model, the dispersion of effective permittivity is within 2–3% relative error for two-layer and within 6–7% relative error for three-layer dielectric microstrip lines for frequency up to 50 GHz. In contrast, for the same structures, the relative errors in previously reported works are above 10% for two layers and above 15% for three-layer dielectric substrates.

Limitations to current long range weather radars include reduced coverage of the lower atmosphere, coarse cross range resolution and coarse temporal resolution due to the mechanical scanning. A proposed network of low cost, short range digital radars for monitoring hydrometeor phenomena is described and its potential benefit in providing lower atmospheric coverage is discussed. The benefits of replacing the scanning antenna at each node of the network with a phased array are also discussed.

th Generation Flash Ladar system which produces real-time, 3-dimensional (3D) video in all lighting conditions has been demonstrated to be a significant enabler to enhance the mission capabilities of Unmanned Aerial Vehicles (UAVs). These new capabilities include enhanced Intelligence, Reconnaissance and Surveillance (ISR), Automated Target Recognition (ATR), improved situational awareness, GPS denied (terrain relative) navigation, 3D surface mapping, surface change detection (detection of buried improvised explosive devices), camouflage penetration, autonomous aerial refueling and autonomous landing. Ball Aerospace 5 th Generation Flash Ladar system has benefited from over 6 years of development, is compact, modular, and has been demonstrated to be easily integrated and flight-tested on both fixed-wing and rotorcraft with different optical configurations. This paper presents the results of airborne test activities and sample imagery of our 5 th Generation system and discusses options for repackaging and integrating the system into UAV platforms. I. Introduction all Aerospace has significant experience in providing ladar systems for remote sensing applications. NASA’s CALIPSO lidar was built by Ball and has celebrated a number of operational milestones, including an extension of the 3-year initial mission lifetime and over 1 billion laser firings and associated atmospheric measurements. Further, Ball Aerospace is developing the flash ladar navigation system for NASA’s space exploration missions. These programs leverage Ball’s extensive understanding of ladar systems, real time image processing algorithms, guidance, navigation and control algorithms, laser system engineering, and the phenomenology being exploited. 1

A Microstrip Patch Antenna (MPA) has been fabricated using a Conducting Polymer (CP), Polypyrrole (PPy) as radiating patch on a transparent 3mm thick Plexiglas™ substrate. The bulk DC conductivity of the PPy patch is 2000 S/m and its thickness 120 µm. The MPA was designed for operating at 2 GHz. A similar antenna with Copper (Cu) patch on Plexiglas™ was also fabricated for validating the simulation of PPy antenna and comparing its performance. The results show that the PPy antenna reaches a gain of 5.01 dB at 2.18 GHz as against 6.26 dB at 2.2 GHz for a corresponding Cu patch antenna. The conduction efficiency of Cu-patch antenna is around 80% while that of PPy-patch antenna is around 60%. The results suggest that it might be possible to use CPs in other passive microwave circuit applications.

Radio frequency identification (RFID) systems are part of modern life. They are revolutionizing the way companies run their businesses, cars pay tolls and employees access an office in a building. RFID devices are also making their way quickly into other industries including health care where they are used in remote of monitoring equipment, as tiny chips that identify items in inventory, or are even embedded in surgical sponges for tracking during an operation. Although in many regions RFID regulations are very strict and operators must adhere to the standard, the unpredictable environmental effects on radio propagation can change the way that these devices operate. This paper offers a review of important EMC information relevant to RFID system deployment. It also examines the sources of error in simulations reported in some other publications.

Crash data involving taxis indicates that such drivers are over represented in crashes and are one to two times more likely to be involved in a fatality crash. This study reports on the pre intervention survey to provide a baseline measure of the self-reported attitudes and corresponding driving behaviours of a sample of taxi drivers. Results indicate that some taxi drivers willingly admit to engaging in unsafe driving practices. In addition, preliminary results of a post intervention survey revealed that taxi drivers’ safety perceptions, attitude and behaviours improved after completing a Driving Diary intervention.

Sparse array imaging systems (developed in ultra sound medical imaging) using a co array can be deployed on small UAVs to eliminate grating lobes on a wideband radar. This allows the use of thin film antennas under the aircraft wing using a split transmit and receive aperture. Simulations show side lobes equivalent to an array of 2 times the linear dimension. Apodization reduces sidelobes to -100 dB, but a secondary lobe is apparent at 0.5-0.8 π. Z transform apodization will reduce the secondary lobe. It can be eliminated entirely using sub kernel convolution with the Z transform. (5 pages)

Radar requirements differ from commercial Radio-Over-Fibre (ROF) systems. High signal to noise ratio (SNR) and spurious free dynamic range (SFDR) in a photonic beam forming architecture are paramount. The architecture described in this paper uses phase modulation to overcome previous limitations. It provides high SNR, low-distortion mixing, enabling optical systems to be used in radar, beamforming and similar applications. (5 pages)

Toolmaking is an industry that creates metal moulds, generally of durable tool steels, for producing vacuum-formed and injection moulded plastic parts, which are used in thousands of everyday items such as mobile phones. At present toolmaking is labour intensive with each machining operation requiring manual supervision. The FASTOOL project was a European Union funded collaboration that was aimed at reducing the manpower content of mould toolmaking, and extending the working day. This paper focuses on one element which utilised specially created scheduling and control software that operated an automated overhead gantry system and could remotely start the workshop machines. The software was completely object oriented which allows future proofing by creating new objects for new machines. The results demonstrate that this manufacturing process can be automated, leading to better working conditions for employees and an increase in efficiency and profitability.

Contemporary policy debates on the macroeconomics of aid often concentrate on short-run Dutch disease effects, ignoring the possible supply side impact of aid— financed public expenditure. We develop a simple model of aid and public expenditure in which public infrastructure capital generates an inter-temporal productivity spillover for both tradable and non-tradable sectors, where these productivity effects may display sector-specific biases. The model also allows for non-homothetic demands. We then use an extended version of this model, calibrated to contemporary conditions in Uganda, to simulate the effect of a step increase in net aid flows. Our simulations show that beyond the short-run, where Dutch disease effects are present, the relationship between enhanced aid flows, real exchange rates and welfare is less straightforward than simple models of aid suggest. We show that public infrastructure which generates a productivity bias in favour of non-tradable production delivers the largest aggregate return to aid, with the real exchange rate appreciation reduced or reversed and enhanced export performance, but it does so at the cost of a deterioration in the income distribution. Income gains accrue predominantly to urban skilled and unskilled households, leaving the rural poor relatively worse off. Under plausible parameterizations of the model the rural poor may also be worse off in absolute terms.

We introduce the Network Photonics' Crosswave as the first commercially-available, MEMS-based wavelength selective switch. The CrossWave combines the functionality of signal demultiplexing, switching and re-multiplexing in a single all-optical operation using a dispersive element and 1-D MEMS. 1-D MEMS, where micronurrors are configured in a single array with a single mirror per wavelength, are fabricated in a standard surface micromachining process. In this paper we present three generations of micromirror designs. With proper design optimization and process improvements we have demonstrated exceptional mirror flatness (

Probably the most enduring result in the theory of optimum income taxation is that, for a sufficiently thin upper tail to the skill distribution, the marginal tax rate should fall rather than rise with income. This paper shows that this result is highly sensitive to a very strong informational assumption, namely that earnings exactly reflect a worker's contribution to output. While the formal structure of the optimum problem is altered only slightly when earnings are allowed to be less than perfectly correlated with productivity, the shape of the optimum schedule is very sensitive to this relaxation. For high but imperfect correlation, optimum schedules look rather like those traditionally chosen by governments, with the marginal rate rising over high incomes and possibly U-shaped over the whole distribution.

It has been argued that the institutions of the CFA Franc zone may have reduced inflation but that they also induced misalignment of the real exchange rate and that this is the explanation for their dismal revenue performance. This paper uses a panel of 22 countries in sub-Saharan Africa to estimate revenue performance over the period from 1980 to 1996. It finds that the poor cumulative relative revenue performance of the franc zone countries is mainly attributable to differences in environmental and structural factors, and that different responses to changes in the equilibrium real exchange rate, but that the misalignment of the real exchange rate also played a part.

Objective To evaluate hereditary and acquired hemostatic abnormalities associated with recurrent spontaneous early (first-trimester) abortions. Method A group of 56 Greek women with two or more unexplained primary spontaneous abortions, and a reference group of 148 women without a history of recurrent abortions, were screened for hypercoagulability. A randomly selected population of first-trimester pregnant women was also chosen for factor V Leiden genetic screening. Results A total of 21% of the women with recurrent abortions, compared with 12% of the reference group, showed increased activated protein C resistance. Fourteen per cent had positive lupus anticoagulant, compared with 11.5% of the reference group. For the rest of the parameters, there was no difference between the two groups. Of 22 women studied for factor V Leiden, one was homozygous and one was heterozygous. Results were compared using Fisher’s exact test and two-tailed Student’s t tests. Conclusions Increased activated protein C resistance appears to be an important factor in women with recurrent abortions. These data indicate the need for routine investigation of activated protein C resistance in women with recurrent abortions.

Thy monolithic integration of MicroElectroMechanical Systems (MEMS) with the driving, controlling, and signal processing electronics promises to improve the performance of micromechanical devices as well as lower their manufacturing, packaging, and instrumentation costs. Key to this integration is the proper interleaving, combining, and customizing of the manufacturing processes to produce functional integrated micromechanical devices with electronics. We have developed a MEMS-first monolithic integrated process that first seals the micromechanical devices in a planarized trench and then builds the electronics in a conventional CMOS process. To date, most of the research published on this technology has focused on the performance characteristics of the mechanical portion of the devices, with little information on the attributes of the accompanying electronics. This work attempts to reduce this information void by presenting the results of SPICE Level 3 and BSIM3v3.1 model parameters extracted for the CMOS portion of the MEMS-first process. Transistor-level simulations of MOSFET current, capacitance, output resistance, and transconductance versus voltage using the extracted model parameters closely match the measured data. Moreover, in model validation efforts, circuit-level simulation values for the average gate propagation delay in a 101-stage ring oscillator are within 13 - 18% of the measured data. These results establish the following: (1) the MEMS-first approach produces functional CMOS devices integrated on a single chip with MEMS devices and (2) the devices manufactured in the approach have excellent transistor characteristics. Thus, the MEMS-first approach renders a solid technology foundation for customers designing in the technology.