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Search Results: 1 - 10 of 1907 matches for " Heather Verkade "
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HIV Prevention in Papua New Guinea: Is It Working or Not?  [PDF]
Heather Worth
World Journal of AIDS (WJA) , 2012, DOI: 10.4236/wja.2012.23016
Abstract: Introduction: There is a global call for structural approaches to HIV that go beyond awareness and HIV testing to approach prevention work via the social and economic drivers of the epidemic. Papua New Guinea is the epicentre of the HIV epidemic in the Pacific, with an adult prevalence rate of 0.9%. Since 2004, there has been a concerted response to HIV, with vastly increased rates of HIV testing and roll-out of antiretroviral therapy, and considerable funding for HIV prevention. Objectives: While incidence is slowing there are still a considerable number of new infections each year and many commentators are worried that HIV prevention is not working in that country. This article aims to critically examine HIV prevention programs in Papua New Guinea to show whether HIV prevention is effectiveness in reaching those most vulnerable to infection. Methods: Using data from HIV prevention programs and behavioural surveys this article will assess how HIV prevention has been carried out and the effectiveness of those programs. Results: There is little evidence to indicate that HIV prevention in Papua New Guinea, particularly among those most at risk of HIV has been successful. Conclusion: there is a dearth of HIV prevention interventions in Papua New Guinea that go beyond awareness-raising to deal with the structural drivers of the epidemic.
Synthesis and characterization of [(CO)4FeL-L] and [(CO)4FeL-LFe(CO)4] wherein L-L is N(CH2CH2)3N and also P(NMeNMe)3P in the latter complex: single crystal X-ray molecular structure of [Fe(CO)4DABCO]
Matos, Robson M.;Verkade, John G.;
Journal of the Brazilian Chemical Society , 2003, DOI: 10.1590/S0103-50532003000100012
Abstract: herein we report the syntheses and characterization of the novel title mono- and dinuclear compounds from pentacarbonyliron. they were obtained in a stepwise manner by uv irradiation of [fe(co)5] with the appropriate ligand in thf and were characterized by 1h, 13c, 13c{1h} 31p and 31p{1h} nmr spectroscopy, by ir spectroscopy and by elemental analysis. the single crystal x-ray molecular structure of [fe(co)4(dabco)] is described. the 13c{1h} nmr spectra of each of the title complexes reveal their fluxional behavior, which presumably occurs via berry pseudorotation.
Estimating the benefits of single value and probability forecasting for flood warning
J. S. Verkade,M. G. F. Werner
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2011,
Abstract: Flood risk can be reduced by means of flood forecasting, warning and response systems (FFWRS). These systems include a forecasting sub-system which is imperfect, meaning that inherent uncertainties in hydrological forecasts may result in false alarms and missed events. This forecasting uncertainty decreases the potential reduction of flood risk, but is seldom accounted for in estimates of the benefits of FFWRSs. In the present paper, a method to estimate the benefits of (imperfect) FFWRSs in reducing flood risk is presented. The method is based on a hydro-economic model of expected annual damage (EAD) due to flooding, combined with the concept of Relative Economic Value (REV). The estimated benefits include not only the reduction of flood losses due to a warning response, but also consider the costs of the warning response itself, as well as the costs associated with forecasting uncertainty. The method allows for estimation of the benefits of FFWRSs that use either deterministic or probabilistic forecasts. Through application to a case study, it is shown that FFWRSs using a probabilistic forecast have the potential to realise higher benefits at all lead-times. However, it is also shown that provision of warning at increasing lead-time does not necessarily lead to an increasing reduction of flood risk, but rather that an optimal lead-time at which warnings are provided can be established as a function of forecast uncertainty and the cost-loss ratio of the user receiving and responding to the warning.
Estimating the benefits of single value and probability forecasting for flood warning
J. S. Verkade,M. G. F. Werner
Hydrology and Earth System Sciences Discussions , 2011, DOI: 10.5194/hessd-8-6639-2011
Abstract: Flood risk can be reduced by means of flood forecasting, warning and response systems (FFWRS). These systems include a forecasting sub-system which is imperfect, meaning that inherent uncertainties in hydrological forecasts may result in false alarms and missed floods, or surprises. This forecasting uncertainty decreases the potential reduction of flood risk, but is seldom accounted for in estimates of the benefits of FFWRSs. In the present paper, a method to estimate the benefits of (imperfect) FFWRSs in reducing flood risk is presented. These benefits include not only the reduction of flood losses due to a warning response, but also consider the costs of the warning response itself, as well as the costs associated with forecasting uncertainty. The method allows for estimation of the benefits of FFWRSs that use either deterministic or probabilistic forecasts. Through application to a case study, it is shown that FFWRSs using a probabilistic forecast have the potential to realise higher benefits at all lead-times. However, it is also shown that provision of warning at increasing lead-time does not necessarily lead to an increasing reduction of flood risk, but rather that an optimal lead-time at which warnings are provided can be established as a function of forecast uncertainty and the cost-loss ratio of the user receiving and responding to the warning.
Synthesis and characterization of [(CO)4FeL-L] and [(CO)4FeL-LFe(CO)4] wherein L-L is N(CH2CH2)3N and also P(NMeNMe)3P in the latter complex: single crystal X-ray molecular structure of [Fe(CO)4DABCO]
Matos Robson M.,Verkade John G.
Journal of the Brazilian Chemical Society , 2003,
Abstract: Herein we report the syntheses and characterization of the novel title mono- and dinuclear compounds from pentacarbonyliron. They were obtained in a stepwise manner by UV irradiation of [Fe(CO)5] with the appropriate ligand in THF and were characterized by 1H, 13C, 13C{1H} 31P and 31P{1H} NMR spectroscopy, by IR spectroscopy and by elemental analysis. The single crystal X-ray molecular structure of [Fe(CO)4(DABCO)] is described. The 13C{1H} NMR spectra of each of the title complexes reveal their fluxional behavior, which presumably occurs via Berry pseudorotation.
The Effect of Tick Size on Testing for Nonlinearity in Financial Markets Data  [PDF]
Heather Mitchell, Michael McKenzie
Journal of Mathematical Finance (JMF) , 2011, DOI: 10.4236/jmf.2011.11001
Abstract: The discrete nature of financial markets time-series data may prejudice the BDS and Close Returns test for nonlinearity. Our estimation results suggest that a tick/volatility ratio threshold exists, beyond which the test results are biased. Further, tick/volatility ratios that exceed these thresholds are frequently observed in financial markets data, which suggests that the results of the BDS and CR test must be interpreted with caution.
Calculation of Start-Oscillation-Current for Lossy Gyrotron Traveling-Wave Tube (Gyro-TWT) Using Linear Traveling-Wave Tube (TWT) Parameter Conversions  [PDF]
Heather H. Song
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.51001
Abstract:

The start-oscillation-current of a gyro-TWT (gyrotron traveling-wave tube) determines the stable operating current level of the device. The amplifier is susceptible to oscillations when the operating current level is higher than the start-oscillation current. There are several ways of calculating the start-oscillation current, including using the linear and nonlinear theory of a gyro-TWT. In this paper, a simple way of determining the start-oscillation current of lossy gyro-TWT is introduced. The linear TWT parameters that include the effects of synchronism, loss, and gain, were converted to gyro-TWT parameters to calculate the start-oscillation-current. The dependence on magnetic field, loss, and beam alpha was investigated. Calculations were carried out for a V-band gyro-TWT for both operating and competing modes. The proposed method of calculating the start-oscillation current provides a simple and fast way to estimate the oscillation conditions and can be used for the design process of a gyro-TWT.

A Novel Compact Microstrip Elliptical Patch Resonator Filter with Tunable Bandwidth  [PDF]
Ruwaybih Alsulami, Heather Song
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.52012
Abstract:

A novel elliptical patch resonator for a compact bandpass filter with tunable bandwidth is presented. This bandpass filter has the advantage of great flexibility in which the center frequency can be changed easily. The bandwidth of this filter can be modified by simply changing one variable, and this makes the proposed design unique. The order of the elliptical patch resonator can be increased, and three types of different orders of the same design are compared. The proposed filter can be used for future compact advanced wireless communication systems.

Broadband Miniaturized Bandpass Filter with Circular Stubs for Compact Wireless and Mobile Communication Systems  [PDF]
Yulan Zhang, Heather Song
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.53018
Abstract:

A miniaturized square resonator bandpass filter with circular stubs is designed, fabricated, and characterized. Analytical calculations were carried out to determine the critical filter parameters and the design was optimized using a 3D electromagnetic finite-element solver. The measured results were in good agreement with the designed results. The proposed filter exhibits significant improvement in bandwidth compared to the conventional square resonator bandpass filters.

Double-Sided Microstrip Circular Antenna Array for WLAN/WiMAX Applications  [PDF]
Ruwaybih Alsulami, Heather Song
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.54029
Abstract:

The design, fabrication, and characterization of the microstrip circular antenna arrays were presented. The proposed antennas were designed for single band at 2.45 GHz and dual bands at 3.3 - 3.6 and 5.0 - 6.0 GHz to support WLAN/WiMAX applications. The proposed single and dual band antennas showed omnidirectional radiation pattern with the gain values of 3.5 dBi at 2.45 GHz, 4.0 dBi at 3.45 GHz, and 3.3 dBi at 5.5 GHz. The dual band antenna array was placed on both top and bottom layers to obtain the desired antenna characteristics. The proposed double-sided dual band antenna provides omnidirectional radiation pattern with high gain.

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