bluuebunny/crossref_metadata_2025 huggingface dataset:
Bandwidth analysis in the curved WDM waveguide coupler
Authors: Chen Ye , Joines William T.
Published: February 2004

The curved WDM waveguide coupler is presented and analyzed in this paper. Compared with the traditional straight coupler, the curved coupler has the advantage of achieving a wider bandwidth. Waveguide theory and the beam propagation method (BPM) are employed to analyze the operation of the couplers. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 451–455, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20003
Solution of “switched element” array synthesis problems using the parallel generalized projection algorithm
Authors: Swierczynski Tom , McNamara Derek A.
Published: February 2004

In certain antenna arrays (“switched‐element” arrays), some of the radiating elements are turned on or off during operation to provide some desired reconfigurability at different times, or are effectively turned on or off at different frequencies, through the use of filters connected to groups of radiating elements, in order to retain the same performance over wide‐frequency bands. In such circumstances, the excitations of the elements must be the same, irrespective of whether all or only some of the elements are being used. Thus, one may wish to synthesize an array (that is, determine its element excitations) so that the required performance is obtained under different sets of circumstances. In this paper, we indicate how the use of a parallel approach allows the method of generalized projections to be used for such synthesis problems, and demonstrate its use for a specific example. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 465–471, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20006
Characteristics and potential applications of nonlinear left‐handed transmission lines
Authors: Caloz Christophe , Lin I‐Hsiang , Itoh Tatsuo
Published: February 2004

The characteristics of nonlinear left‐handed (NL‐LH) transmission lines (TLs) are discussed for the first time. A LH‐TL with varactor‐diode series capacitance is analyzed in terms of dispersion and nonlinearity characteristics, and its voltage‐wave partial differential equation is derived. Numerical responses of the NL‐LH‐TL to harmonic and pulse waves illustrate the conjoint effects of frequency dispersion and nonlinearity. Potential applications are suggested. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 471–473, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20007
Design of a novel transversal filter
Authors: Jee Ki Mann , Park Dong Chul
Published: February 2004

A novel transversal filter using triple‐coupled‐line directional couplers and its design method are proposed. The performance of the proposed filter is verified by full‐wave analysis and measurement. The measured result is compared with the simulated one and good agreement is achieved. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 474–476, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20008
A simple method to determine the time‐step size to achieve a desired dispersion accuracy in ADI‐FDTD
Authors: Sun Guilin , Trueman C. W.
Published: February 2004

This paper presents a simple approach to determine the time‐step size required in the alternate‐direction‐implicit finite‐difference time‐domain (ADI‐FDTD) method in order to obtain a desired numerical dispersion accuracy. The Courant number, the desired dispersion accuracy, and the maximum mesh size Δmax = max(Δx, Δy, Δz) are governed by the numerical dispersion relation, which can be solved by a simple root‐finding algorithm to evaluate the Courant number and hence the time‐step size for a given mesh size and accuracy. The time‐step size is independent of the aspect ratio. To determine if ADI‐FDTD is more efficient than the Yee's FDTD, this paper provides a simple relation to evaluate the relative Courant–Friedrich–Levy number (CFLN) from the Courant number and the aspect ratio. The ADI‐FDTD method is more efficient than Yee's FDTD when the aspect ratio is high or the mesh density is very large. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 487–490, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20012
Compact circularly polarized microstrip antenna on organic magnetic substrate
Authors: Zhong Shun‐Shi , Cui Jun‐Hai , Xue Rui‐Feng , Niu Jun‐Wei
Published: February 2004

A novel compact slotted microstrip antenna for circular polarization (CP), using a new type of organic magnetic substrate for the first time, is proposed in this paper. The proposed antenna is analyzed using the FDTD method and demonstrated by experiment. The measured results of proposed CP square and circular patches show that this new magnetic substrate design not only reduces the antenna's size, but also provides much wider impedance and CP bandwidth. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 497–500, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20014
Conception and realization of an angular optical sensor
Authors: Cherbi L. , Mehenni M. , Aksas R.
Published: February 2004

In this work, an angular sensor using optical fiber is achieved. The principle of attenuation of the intensity of the luminous wave in the optical fiber (curved to deduct the angle of curvature) is used. A mechanical system controlled by a PC is conceived to simulate the articulation of a human being in order to test the optical sensor on the during various angular displacements of the articulation. According to the variation of this attenuation, a measure of angle is deducted. This process may offer a useful technique for use in functional rehabilitation, which requires a quantification of the angular kinematics of movements. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 500–503, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20015
Dual‐band reconfigurable antenna for wireless communications
Authors: Chen W. H. , Feng Z. H. , Fan M. Y. , Furuya Y.
Published: February 2004

A novel planar‐reconfigurable dipole antenna on ungrounded dielectric slab with parasitic reflector which has dual‐band and steerable endfire pattern characteristics, is proposed. A prototype is fabricated and both simulated and measured results validate the advantages of this antenna. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 503–505, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20016
Omnidirectional uniplanar elecromagnetically coupled antenna array
Authors: Nesic Aleksandar , Nesic Dusan
Published: February 2004

A completely new type of simple uniplanar antenna array with omnidirectional pattern is proposed. The antenna consist of three coplanar strips (TCS), a coplanar waveguide (CPW) with finite narrow ground strips, electromagnetically coupled with four pairs of strips which play the role of the radiating elements. A prototype of the proposed antenna array at 10.5‐GHz frequency is simulated, optimized, and realized. The gain is 8 dBi with a practically pure omnidirectional pattern. The concept of this proposed antenna array may be used for frequencies from some hundreds of MHz to about 30 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 516–518, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20020
Design of an exponentially‐tapered TEM horn antenna for the wide broadband communication
Authors: Choi Hyoungjin , Lee Sangseol
Published: February 2004

A transverse electromagnetic (TEM) horn antenna is designed and realized using exponentially tapered conductor flares for wireless communications. This exponentially tapered structure of the flares decreases the impedance mismatching a lot and reduces the size and cost of the TEM horn. The VSWR of the antenna is less than 2 in the frequency band of 74.4 MHz to 1.19 GHz, and its gain is more than 8.3 dBi over 200 MHz. Those performances show that the designed TEM horn antenna has wide broadband characteristics. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 531–534, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20025
Priorities, government institutions and foreign assistance in the fight against HIV/AIDS in Russia
Authors: Davis Christopher , Dickinson Ben
Published: February 2004

This article argues that for a number of reasons, the Russian state has had limited success in tackling the growing problem of HIV/AIDS. It begins with brief discussions of the health context of HIV/AIDS in the Russian Federation and the development of institutions in Russia post‐1991. It then discusses the attempts that have been made thus far to tackle the HIV/AIDS epidemic, both on the part of the federal government and with the aid of international donor funding. It is argued that a number of factors have contributed to Russia's lack of success in tackling HIV/AIDS. Firstly, the infection has been interpreted as a health problem rather than as a phenomenon which impacts on all aspects of public life. Secondly, there have been weak incentives at the federal level, which has resulted in a lack of a coordinated approach to HIV/AIDS at the national level. Thirdly, there have been regional variations in the autonomy and independence from the federal state impacting on the struggle against HIV in the Russian regions. Evidence from research undertaken by DFID is drawn upon to illustrate these variations in tackling HIV/AIDS. Copyright © 2004 John Wiley & Sons, Ltd.
Ethnicity, decentralisation and the fissile state in Georgia
Authors: Jackson Paul
Published: February 2004

This article addresses the problems entailed in decentralising a successor state of the former Soviet Union. On many different scales, Georgia should be a wealthy country. The population is well educated, there is rich agricultural land, a thriving wine industry, several mineral extraction industries and access to oil. The central argument of this article is that it is governance, or rather the failure of governance that is at the heart of many of Georgia's problems—in particular, a failure over a number of years to find a balance between the considerable ethnic diversity of the country and their aspirations regarding self‐government, and the need for the assertion of central power from Tblisi in occupying the power vacuum left by the demise of the Soviet Union. The structure of the article moves through an analysis of the context of decentralisation, into a brief survey of the major ethnic groups and the nature of the local government system, paying particular attention to the attempts by Tblisi to provide a coherent glue for a state that is liable to break apart. The concept of the ‘fissile state’ is used to convey this brittle context within which institutional reform needs to take place given the pressures from below and the pressures exerted by external actors as Georgia seeks to move closer to the European polity. Copyright © 2004 John Wiley & Sons, Ltd.
HIV/AIDS, governance and development: the public administration factor
Authors: Moran Dominique
Published: February 2004

This paper provides an overview of the literature concerned with the impact of HIV on public administration, looking in particular at projections of the impact of HIV/AIDS on public expenditure, the impact of attrition on the health and education sectors and on the civil service as a whole. ‘Success stories’ such as Uganda and Senegal are discussed through their representation in the literature, and ‘political commitment’ is identified as a critical but under‐theorised factor in tackling HIV. Having taken as its starting point the existing work on HIV and governance, the paper then considers the impact of the epidemic in conditions of state vacuum—conflict situations. The paper concludes that governance is both victim of, and part of the solution to, the problems of HIV/AIDS. Copyright © 2004 John Wiley & Sons, Ltd.
Interpreting reproductive rights: institutional responses to the agenda in the 1990s
Authors: Zhang Heather Xiaoquan , Locke Catherine
Published: February 2004

This article reviews the way in which three very different international organisations concerned with reproductive health policy responded to the reproductive rights agenda during the 1990s. The intention is not to evaluate these responses but to describe how these organisations saw their roles with respect to establishing and promoting reproductive rights in developing countries. We seek to explore their different strategies of defining and interpreting rights, to examine the imperatives behind these strategies and to consider how these variously fed into the practical actions and agendas with which these organisations were engaged. The organisations included were the Women's Global Network for Reproductive Rights, the International Federation of Family Planning Associations and the UK's Department for International Development. Their diverse understandings about implementing reproductive rights contribute to a plural political environment in which these rights and their interpretation are debated. For all the three, their particular conception of reproductive rights is an important organising principle through which their efforts around reproductive health are given wider meaning. Copyright © 2004 John Wiley & Sons, Ltd.
The politics of action on AIDS: a case study of Uganda
Authors: Putzel James
Published: February 2004

This article examines the political dimensions of Uganda's progress in bringing a generalised HIV/AIDS epidemic under control. The article documents the history of the political processes involved in Uganda's battle against HIV/AIDS and analyses the complexities of presidential action and the relation between action at the level of the state and that taken within societal organisations. By the mid‐1980s, Uganda was experiencing a full‐blown epidemic, the virulence of which was connected with social dislocation and insecurity related to economic crisis and war. Political authorities faced the same challenge as other regimes experiencing the onslaught of AIDS in Africa. The epidemiological characteristics of HIV and AIDS—transmission through heterosexual activities, with a long gestation period, affecting people in the prime of their productive life—meant that action required wide‐reaching changes in sexual behaviour, and the educational activities to achieve this, as well as relatively complex systems to monitor the virus and control medical practices (blood supplies, injection practices, mitigating drug delivery). The centralist character of the Museveni regime was crucial not only to mobilising state organisations and foreign aid resources, but also to ensuring significant involvement from non‐state associations and religious authorities. The Ugandan experience demonstrates that there is a tension between the requirements for systematic action that a strong public authority can deliver and the need to disseminate information requiring a degree of democratic openness. The President was able to forge a coalition behind an HIV/AIDS campaign in part because the virus largely ignored the privileges of wealth and political power. With the development of antiretroviral therapy and the access that the wealthy can gain to these drugs, this basis for the broadest possible coalition to fight HIV/AIDS may be weakened in the future. Copyright © 2004 John Wiley & Sons, Ltd.
Who controls the machine, III: accountability in the results‐based revolution
Authors: Mathiason John R.
Published: February 2004

Following up on two previous analyses of the efforts of Member States to solve the problems of command and control in the United Nations and its organisations, the article focuses on the latest effort, the institution of results‐based budgeting. The approach as applied to assessed budgets is critical for the maintenance of support of major contributors to the United Nations and other international organisations. After reviewing the problems inherent in previous efforts at using programme planning to control the organisation and make it accountable, the article focuses on the use of monitoring and evaluation as means of holding organisations accountable for producing results and on the conditions necessary for this to be effective. It argues that refocusing the work of the Committee for Programme and Coordination and the Office of Internal Oversight Services as its independent secretariat could make the results‐based revolution work and Member States finally to control the machine. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis, characterization and flame retardancy of methacrylated phosphate/diphosphate
Authors: Zhu Shengwu , Shi Wenfang
Published: February 2004

Methacrylated phosphate (MAP) and diphosphate (MADP) and were synthesized using diethylphosphoric acid and glycidyl methacrylate, and were characterized by FTIR, NMR and elemental analysis. The thermostability and combustion behaviours of UV‐cured MAP, MADP and their blend films were investigated by thermogravimetric analysis, limiting oxygen index (LOI) and cone calorimeter tests. The results obtained have shown that the samples containing a higher percentage of MAP exhibit relatively lower thermostability at lower temperatures while higher thermostability at elevated temperatures and more char was formed compared with those containing lower percentage of MAP. The average heat release rate (HRR), the smoke extinction area (SEA) and the total smoke production (TSP) during combustion decreased by increasing the MPA content in the films. The LOI values increased from 26.8 to 28.5 by increasing the content of MADP, which depended on the increasing gel content of the UV‐cured films. Compared with MADP, MAP was better in a real fire as it displayed lower HRR, SEA and TSP values, although the LOI was lower than that of MADP. These new compounds can effectively improve flame retardancy if used as components in UV‐curing formulations. Copyright © 2004 Society of Chemical Industry
Cibacron Blue F3GA‐attached magnetic poly(2‐hydroxyethyl methacrylate) beads for human serum albumin adsorption
Authors: Odabaşı Mehmet , Denizli Adil
Published: February 2004

An affinity dye ligand, Cibacron Blue F3GA, was covalently attached onto magnetic poly(2‐hydroxyethyl methacrylate) (mPHEMA) beads for human serum albumin (HSA) adsorption from both aqueous solutions and human plasma. The mPHEMA beads, in the size range of 80 to 120 µm, were prepared by a modified suspension technique. Cibacron Blue F3GA molecules were incorporated on to the mPHEMA beads. The maximum amount of Cibacron Blue F3GA attachment was obtained as 68.3 µmol g−1. HSA adsorption onto unmodified and Cibacron Blue F3GA‐attached mPHEMA beads was investigated batchwise. The non‐specific adsorption of HSA was very low (1.8 mg g−1). Cibacron Blue F3GA attachment onto the beads significantly increased the HSA adsorption (94.5 mg g−1). The maximum HSA adsorption was observed at pH 5.0. Higher HSA adsorption was observed from human plasma (138.3 mg HSA g−1). Desorption of HSA from Cibacron Blue F3GA‐attached mPHEMA beads was obtained by using 0.1 M Tris/HCl buffer containing 0.5 M NaSCN. High desorption ratios (up to 98% of the adsorbed HSA) were observed. It was possible to re‐use Cibacron Blue F3GA‐attached mPHEMA beads without any significant decreases in their adsorption capacities. Copyright © 2004 Society of Chemical Industry
Synthesis and properties of thio‐containing poly(ether ether ketone)s
Authors: Wang Yen‐Zen , Lin Chih‐Hung , Chan Bor‐Wen , Hsieh Kuo‐Huang
Published: February 2004

A series of thio‐containing poly(ether ether ketone) (PEESK) polymers was synthesized by the introduction of thio groups from 4,4′ thiodiphenol (TDP) into the poly(ether ether ketone) (PEEK) structure via reaction between the phenol and aromatic fluoride groups. The effect of the thio groups on the properties of the PEESK materials was investigated. Differential scanning calorimetry (DSC) analysis and X‐ray diffraction (XRD) patterns show a depression in the crystallinity of the PEESKs with incorporation of the content of thio groups in the backbones. The crystalline structure was identified as an orthorhombic structure with lattice constants of a = 7.52 Å, b = 5.86 Å and c = 10.24 Å for all crystallizable PEESKs. The crystalline structures of the thio‐containing PEEK polymers were the same as that of the neat PEEK, which means the thio‐containing block in the whole thio‐containing PEEK molecule is almost excluded from the crystalline structure and the crystals are completely formed by ‘non‐thio’ blocks only. Due to the glass transition temperature (Tg) and melting temperature (Tm) depression with increase in the TDP content in the reaction system, the processability of the resultant thio‐containing PEEKs could be effectively improved. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of ABA‐type block copolymers of trimethylene carbonate and ϵ‐caprolactone
Authors: Jia Yong Tang , Kim Hak Yong , Gong Jian , Lee Duok Rae , Ding Bin , Bhattarai Narayan
Published: February 2004

This paper describes the synthesis of a series of ABA‐type triblock copolymers of trimethylene carbonate and ϵ‐caprolactone with various molar ratios and analyses the thermal and mechanical properties of the resulting copolymers. The structures of the triblock copolymers were characterized by 1H and 13C nuclear magnetic resonance spectroscopy, FT‐IR spectroscopy and gel permeation chromatography. Results obtained from the various characterization methods proves the successful synthesis of block copolymers of trimethylene carbonate and ϵ‐caprolactone. The thermal properties of the block copolymers were investigated by differential scanning calorimetry. The Tm and ΔHm values of the copolymers decrease with increasing content of trimethylene carbonate units.

Two Tgs were found in the copolymers. Furthermore, both of the Tg values increased with increasing content of trimethylene carbonate units. The mechanical properties of the resulting copolymers were studied by using a tensile tester. The results indicated that the mechanical properties of the block copolymers are related to the molar ratio of trimethylene carbonate and ϵ‐caprolactone in the copolymers, as well as the molecular weights of the resulting copolymers. The block copolymer with a molar composition of 50/50 possessed the highest tensile stress at maximum and modulus of elasticity. Block copolymers possessing different properties could be obtained by adjusting the copolymer compositions. Copyright © 2004 Society of Chemical Industry
Grafting of vinyl acetate onto low density polyethylene—starch biodegradable films for printing and packaging applications
Authors: Ghosh RN , Jana T , Ray BC , Adhikari Basudam
Published: February 2004

Starch‐based biodegradable low‐density polyethylene (LDPE) films were used for graft copolymerization of vinyl acetate with ceric ammonium nitrate (CAN) in aqueous acidic medium as redox initiator with nitric acid. The extent of grafting was examined by Fourier‐transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The objective behind the grafting of vinyl acetate onto the LDPE–starch biodegradable films is to make these suitable for printing and packaging applications without affecting the biodegradability of the original films. Copyright © 2004 Society of Chemical Industry
Structure and mechanical properties of polysulfone‐based in situ composites
Authors: García M , Eguiazábal JI , Nazábal J
Published: February 2004

Composites based on the polysulfone of bisfenol A (PSF) and a liquid‐crystalline copolyester (Rodrun 5000) were obtained by two processing methods, (1) direct injection moulding (DI) and (2) extrusion followed by injection moulding (PI), across the whole composition range. The blends were immiscible and showed two pure amorphous phases. The inferior mechanical properties of PI blends, and their more difficult processing, meant that the PI procedure is not suitable in these blends. The generally linear relationship of the Young's modulus of the DI blends is due to the counteracting effects of the large orientation of the skin and its low thickness. The improvement in notched impact strength of PSF on the addition of small amounts of LCP indicated an important reduction in its notch sensibility. The tensile strength behaviour was close to linearity, with the exception of the 20/80 blend in which it was synergistic. This had been seen in previous thermoplastic/LCP blends, and depicts a behaviour reminiscent of rubber‐toughened blends. Copyright © 2004 Society of Chemical Industry
Use of temperature‐modulated DSC in kinetic analysis of a catalysed epoxy–anhydride system
Authors: Montserrat S , Pla X
Published: February 2004

The curing kinetics of a catalysed epoxy‐anhydride system was studied by temperature‐modulated differential scanning calorimetry. The chemical‐controlled regime was analysed by empirical kinetic equations. The diffusion‐controlled regime was detected by the diffusion factor, DF(α,T), which was calculated from the ratio of the experimental rate to the chemical reaction rate. DF(α,T) was compared with a mobility factor, MF(α,T), which was obtained by measuring the modulus of the complex heat capacity |Cp*|. The equivalence of the two factors allowed the diffusion‐controlled regime to be studied using the |Cp*| signal. However, the results obtained in the epoxy–anhydride system showed a limitation to the method, and this is discussed in terms of the modulation period necessary for the variation in MF(α,T) to occur in the same conversion interval as does DF(α,T). Copyright © 2004 Society of Chemical Industry
Polyaniline prepared in the presence of various acids: a conductivity study
Authors: Stejskal Jaroslav , Hlavatá Drahomíra , Holler Petr , Trchová Miroslava , Prokeš Jan , Sapurina Irina
Published: February 2004

Polyaniline (PANI) was prepared by the oxidation of aniline in the presence of various inorganic and organic acids at 20 °C and −50 °C. When strong acids were used, the conductivity of the protonated PANI was typically 1–10 S cm−1. The results indicate that the protonation of PANI in media containing carboxylic acids was achieved with the help of sulfuric acid produced during the reaction with ammonium peroxydisulfate. The conductivity of PANI prepared under such conditions was reduced. Partial benzene‐ring sulfonation has been proposed to explain the wide range in conductivity of PANI bases, 10−11–10−7 S cm−1. The densities of the samples reflect the nature of the acid used. The densities of the corresponding PANI bases exhibit much less variation. Molecular weight and degree of crystallinity of PANI are higher when the polymerization is carried out at −50 °C. The conductivity of the PANI is determined mainly by way of protonation. The effects of molecular weight and of crystallinity on PANI conductivity are marginal. Copyright © 2004 Society of Chemical Industry
Morphological and thermal characterization of interpolymer complexes and blends based on poly(acrylic acid) and hydroxypropylcellulose
Authors: Khutoryanskiy Vitaliy V , Cascone Maria Grazia , Lazzeri Luigi , Barbani Niccoletta , Nurkeeva Zauresh S , Mun Grigoriy A , Dubolazov Artem V
Published: February 2004

Interpolymer complexes and blends were prepared based on poly(acrylic acid) and hydroxypropylcellulose. The structural features of polycomplexes and blends were evaluated by scanning electron microscopy and thermal analysis. It was found that the interpolymer complex obtained as a result of co‐precipitation of the polymeric components is characterized by an uniform structure which indicates the complete miscibility between the components. Films were prepared based on blends of neutralized poly(acrylic acid) and hydroxypropylcellulose. In this case the two components resulted immiscible because of the lack of intermolecular hydrogen bonding. Copyright © 2004 Society of Chemical Industry
Mathematical Modeling and Experimental Identification of an Unmanned Helicopter Robot with Flybar Dynamics
Authors: Kim S. K. , Tilbury D. M.
Published: February 2004

This paper presents a mathematical model for a model‐scale unmanned helicopter robot, with emphasis on the dynamics of the flybar. The interaction between the flybar and the main rotor blade is explained in detail; it is shown how the flapping of the flybar increases the stability of the helicopter robot as well as assists in its actuation. The model helicopter has a fast time‐domain response due to its small size, and is inherently unstable. Therefore, most commercially available model helicopters use the flybar to augment stability and make it easier for a pilot to fly. Working from first principles and basic aerodynamics, the equations of motion for full six degree‐of‐freedom with flybar‐degree of freedom are derived. System identification experiments and results are presented to verify the mathematical model structure and to identify model parameters such as inertias and aerodynamic constants. © 2004 Wiley Periodicals, Inc.
Inferior vena cava thrombosis presenting as non‐immune hydrops in the fetus of a woman with diabetes
Authors: Weissmann‐Brenner A. , Ferber A. , O'Reilly‐Green C. , Avila C. , Grassi A. , Divon M. Y.
Published: February 2004

We present a rare case of non‐immune hydrops fetalis (NIHF) caused by a thrombus in the inferior vena cava in a neonate with low levels of anti‐thrombin III. The diagnosis of (NIHF) was made in utero in a 43‐year‐old woman with poorly controlled gestational diabetes who subsequently developed pre‐eclampsia. Cesarean section was performed due to fetal compromise and worsening pre‐eclampsia. The thrombus resolved after neonatal treatment with heparin. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Analysis of sonographic features for the differentiation of benign and malignant breast tumors of different sizes
Authors: Chen S.‐C. , Cheung Y.‐C. , Su C.‐H. , Chen M.‐F. , Hwang T.‐L. , Hsueh S.
Published: February 2004

Objective

To analyze the value of various sonographic features in differentiating benign from malignant breast tumors of different sizes to improve the diagnostic accuracy in small lesions.

Methods

The sonographic features of 1203 histologically confirmed solid breast lesions were prospectively documented with respect to anteroposterior (AP) diameter/width ratio, shape, margin, echogenicity, echotexture, posterior echo and bilateral refraction sign. The sensitivity, specificity and accuracy of breast ultrasound were calculated for lesions grouped according to size (≤ 1, 1.1–2 and > 2 cm). Univariate and multiple logistic regression analyses including calculation of odds ratios for single sonographic features were used to analyze the significance of the different diagnostic features.

Results

The accuracy of breast sonography in differentiating between benign and malignant tumors ≤ 1, 1.1–2 and > 2 cm in size was 75.6%, 86.4% and 88.4%, respectively. Univariate analysis demonstrated that all sonographic features were significant in tumors ≥ 1.1 cm. Shape, margin, echogenicity and echotexture were the significant factors in those tumors ≤ 1 cm. Multiple logistic regression analysis demonstrated that margin, shape, posterior echo and echogenicity were the significant factors for differential diagnosis in tumors > 2 cm. Echogenicity, margin, shape, bilateral refraction sign and echotexture were the significant factors for tumors 1.1–2 cm. On multiple regression analysis, margin was the only significant factor for tumors ≤ 1 cm.

Conclusion

Tumor margin is the most important sonographic feature in evaluating breast lesions in any size group. With the combination of significant factors and emphasis on specific features according to size of lesion, the diagnostic accuracy of ultrasound for the differential diagnosis of malignant and benign tumors may be improved. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Accuracy of sonographically estimated fetal weight in 840 women with different pregnancy complications prior to induction of labor
Authors: Ben‐Haroush A. , Yogev Y. , Bar J. , Mashiach R. , Kaplan B. , Hod M. , Meizner I.
Published: February 2004

Objectives

To evaluate the accuracy of sonographically estimated fetal weight (EFW) shortly before induction of labor in the presence of different pregnancy complications, and to define possible variables affecting it.

Methods

The study sample consisted of 840 women with singleton pregnancies and cephalic presentation who were admitted to our unit for induction of labor between January 1999 and December 2000. All underwent detailed ultrasound assessment for EFW, amniotic fluid index, biophysical profile and placental location. Indications included previous Cesarean section, postdate pregnancy, pregnancy‐induced hypertension, diabetic pregnancy, suspected large‐for‐gestational age (LGA) infants, suspected fetal growth restriction (FGR), oligohydramnios, decreased fetal movements, premature rupture of membranes at or before term. EFW was calculated after measuring fetal abdominal circumference and femur length. The EFW was compared with the weight at delivery, 1–3 days later.

Results

There was a high correlation between EFW and birth weight (R2 = 0.775, P < 0.001). The mean birth weight was 3207 ± 561 g, and mean absolute weight difference was 227 ± 197 g; (absolute range, 0–1700 g; actual range, − 986 to + 1700 g). The mean weight difference was significantly different between the patients with LGA infants, FGR infants and preterm premature rupture of membrances (PPROM) (− 110 ± 281 g, + 113 ± 195 g and + 115 ± 307 g, respectively, P < 0.01). Stepwise linear regression analysis of the effects of maternal and pregnancy characteristics on the weight difference yielded lower gestational age, higher birth weight, anterior placenta, higher gravidity, and younger maternal age as independent and significant variables associated with greater actual weight difference inaccuracy (R2 = 0.099, P < 0.001), and higher birth weight as the only independent and significant variable associated with greater absolute weight difference (R2 = 0.09, P = 0.018).

Conclusions

The sonographic EFW is highly correlated with birth weight. However, clinicians should be aware of the risk of overestimation in pregnancies with suspected LGA and underestimation in pregnancies with PPROM and suspected FGR. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Transvaginal ultrasound detection of multifollicular ovaries in non‐hirsute ovulatory women
Authors: Phy J. , Foong S. , Session D. , Thornhill A. , Tummon I. , Dumesic D.
Published: February 2004

Objectives

To characterize ovarian morphology in a group of ovulatory, non‐hirsute women with infertility and normal circulating levels of gonadotropins and sex steroids.

Methods

Thirty‐three women with normal physical examinations, regular ovulatory menses, and absence of hirsutism (Ferriman–Gallwey score ≤ 7) were studied. No woman had thyroid disease, galactorrhea, polycystic ovary syndrome, 21‐hydroxylase deficiency or diabetes. Two‐dimensional (2D) transvaginal sonography (TVS) was used to measure follicle size and ovarian volume on menstrual cycle day 5. Three‐dimensional (3D) TVS images were stored to determine the number of follicles (measuring 2–10 mm in diameter) in the largest sonographic plane. Fasting blood sampling and oral glucose tolerance testing were performed to assess serum gonadotropin and sex steroid levels as well as glucose tolerance.

Results

The median ovarian volume by 2D‐TVS imaging was 7.2 (range, 2.3–15.8) cm3 (n = 64 ovaries). No follicles were > 10 mm in diameter. The median number of follicles by 3D‐TVS was 4 (range, 2–8) (n = 63 ovaries) in the largest sonographic plane. Fourteen of 63 ovaries (22%) had six or more small follicles in one plane distributed within normal stroma (multifollicular ovary, MFO). No ovary had 10 or more follicles in one plane located within abundant stroma (polycystic ovary). Of 33 women examined, 20 women (61%) had apparently normal ovaries bilaterally, while 13 (39%) had at least one MFO. There were no significant differences between women with and those without MFO in serum gonadotropin and steroid levels or glucose tolerance.

Conclusions

MFO is a common morphological variant in non‐hirsute ovulatory women with normal gonadotropin secretion and ovarian steroidogenesis. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Umbilical venous volume flow and fetal behavioral states in the normally developing fetus
Authors: Boito S. M. E. , Ursem N. T. C. , Struijk P. C. , Stijnen T. , Wladimiroff J. W.
Published: February 2004

Objective

To determine the relationship between umbilical venous (UV) volume flow and fetal behavioral states 1F (quiet sleep) and 2F (active sleep) in normal pregnancies at 36–40 weeks of gestation.

Methods

Fetal behavioral states were established in 17 normal pregnancies by means of combined assessment of fetal heart rate patterns (FHRP), and fetal eye and body movements. UV vessel area (mm2) as obtained by tracing the inner vessel area using Labview and Imaq Vision software and UV time‐averaged flow velocity (mm/s Doppler) were multiplied to calculate UV volume flow (mL/min) including flow/kg fetus. The pulsatility index (PI) in the umbilical artery was also determined. In each woman, all parameters were measured between three and five times in each behavioral state. Data are reported as mean ± 1 SD and analyzed by paired t‐test.

Results

No statistically significant behavioral‐state‐related changes were observed for UV time‐averaged velocity and UV volume flow, resulting in UV volume flow/kg fetus of 69.1 ± 14.9 mL/min*kg at 1F and 71.6 ± 12.1 mL/min*kg at 2F (not significant). A statistically significant increase (P = 0.02) was established for UV cross‐sectional area (46.4 ± 8.6 mm2 vs. 49.0 ± 10.1 mm2) and for fetal heart rate (FHR) from 134.2 ± 10.3 bpm in 1F to 144.2 ± 7 bpm in 2F. Umbilical artery PI was not significantly different between the two behavioral states.

Conclusions

On the basis of high venous vessel wall compliance, the significant increase in UV cross‐sectional area during fetal behavioral state 2F may be determined by a rise in mean venous pressure. The significant rise in FHR may reflect increased fetal cardiac output during state 2F while the resistance at the hepato‐ductal pathway remains relatively constant with the purpose of meeting raised energy demands during the active sleep state. This is further supported by the observed trend towards an increase in UV volume flow. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Relationship between monitoring parameters and perinatal outcome in severe, early intrauterine growth restriction
Authors: Bilardo C. M. , Wolf H. , Stigter R. H. , Ville Y. , Baez E. , Visser G. H. A. , Hecher K.
Published: February 2004

Objective

To investigate whether pathological changes in the umbilical artery (UA), ductus venosus (DV) and short‐term fetal heart variation are related to perinatal outcome in severe, early intrauterine growth restriction (IUGR).

Methods

This multicenter, prospective, longitudinal, observational study was carried out in the Departments of Fetal Medicine and Obstetrics in Hamburg, Amsterdam, Utrecht and London. In 70 singleton pregnancies with IUGR fetuses, delivered at 26–33 weeks of gestation because of antepartum fetal distress, short‐term variation (STV) of fetal heart rate, pulsatility index of the fetal UA (UA PI) and DV pulsatility index for veins (DV PIV) were assessed at least weekly. The final measurement was performed within 24 h of delivery. Standard cut‐off levels (2 SD or 3 SD, absent flow or reversed flow) were used and new cut‐off levels were calculated by means of receiver–operating characteristics analysis. Adverse outcome was defined as perinatal death, cerebral hemorrhage (≥ Grade II) or bronchopulmonary dysplasia before discharge. The predictive value for adverse outcome was calculated for different cut‐off levels of the monitoring parameters, adjusted for gestational age (GA), by multivariate logistic regression analysis. Data were analyzed separately for three different time blocks, namely 8–14, 2–7 and 0–1 days before delivery.

Results

Adverse perinatal outcome occurred in 18/70 (26%) infants. During the last 24 h before delivery DV PIV and UA PI were significantly higher and STV lower in the adverse outcome group, while 2–7 days before delivery only DV PIV was significantly higher. Adverse perinatal outcome could be predicted at 0–1 days before delivery by DV PIV at a cut‐off of three multiples of the SD (odds ratio (OR) 11.3; 95% CI 2.3–57) and GA (OR 0.4; 95% CI 0.3–0.8), at 2–7 days by DV PIV at 2 SD (OR 3.0; 95% CI 0.8–12) and GA (OR 0.5; 95% CI 0.3–0.8) and at 8–14 days by DV PIV at 2 SD (OR 3.9; 95% CI 0.8–20) and GA (OR 0.5; 95% CI 0.3–0.8). Other parameters did not contribute to the multivariate model.

Conclusions

DV PIV measurement is the best predictor of perinatal outcome. This measurement may be useful in timing the delivery of early IUGR fetuses and in improving perinatal outcome, even when delivery may be indicated at an earlier GA. However, as GA was also an important factor influencing outcome, with poorer outcome at earlier gestation at delivery, this hypothesis needs to be tested in a multicenter, prospective, randomized trial. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Evaluation of femur length during the second and third trimesters in fetuses with myelomeningocele
Authors: Williams G. , Coakley F. V. , Qayyum S. , Glenn O. A. , Breiman R. S. , Callen P. W.
Published: February 2004

Objectives

To determine if the femur length of fetuses with myelomeningocele is shorter in the second and third trimesters compared with that of normal fetuses.

Methods

We retrospectively collected measurements of femur length, head circumference, biparietal diameter and abdominal circumference from detailed obstetric ultrasound studies performed during the second and third trimesters in 31 fetuses with myelomeningocele and 43 fetuses with no detectable anomaly. The gestational age predicted by each parameter (based on Hadlock's tables) was compared with the true gestational age (based on last menstrual period), using the ANCOVA test to determine if there was a statistically significant difference between the two groups of fetuses.

Results

There was no significant difference in femur length (P = 0.60) or in abdominal circumference (P = 0.85) between fetuses with myelomeningocele and normal fetuses. Fetuses with myelomeningocele did have a significantly lower biparietal diameter and head circumference (P ≤ 0.001).

Conclusions

Myelomeningocele is not associated with reduced femur length in the second and third trimesters, suggesting that the known postnatal lower extremity foreshortening in patients with myelomeningocele develops late in gestation or after birth. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Femur and humerus length in trisomy 21 fetuses at 11–14 weeks of gestation
Authors: Longo D. , DeFigueiredo D. , Cicero S. , Sacchini C. , Nicolaides K. H.
Published: February 2004

Objective

To determine the value of measuring fetal femur and humerus length at 11–14 weeks of gestation in screening for chromosomal defects.

Methods

Femur and humerus lengths were measured using transabdominal ultrasound in 1018 fetuses immediately before chorionic villus sampling for karyotyping at 11–14 weeks of gestation. In the group of chromosomally normal fetuses, regression analysis was used to determine the association between long bone length and crown–rump length (CRL). Femur and humerus lengths in fetuses with trisomy 21 were compared with those of normal fetuses.

Results

The median gestation was 12 (range, 11–14) weeks. The karyotype was normal in 920 fetuses and abnormal in 98, including 65 cases of trisomy 21. In the chromosomally normal group the fetal femur and humerus lengths increased significantly with CRL (femur length = − 6.330 + 0.215 × CRL in mm, r = 0.874, P < 0.0001; humerus length = − 6.240 + 0.220 × CRL in mm, r = 0.871, P < 0.0001). In the Bland–Altman plot the mean difference between paired measurements of femur length was 0.21 mm (95% limits of agreement − 0.52 to 0.48 mm) and of humerus length was 0.23 mm (95% limits of agreement − 0.57 to 0.55 mm). In the trisomy 21 fetuses the median femur and humerus lengths were significantly below the appropriate normal mean for CRL by 0.4 and 0.3 mm, respectively (P = 0.002), but they were below the respective 5th centile of the normal range in only six (9.2%) and three (4.6%) of the cases, respectively.

Conclusion

At 11–14 weeks of gestation the femur and humerus lengths in trisomy 21 fetuses are significantly reduced but the degree of deviation from normal is too small for these measurements to be useful in screening for trisomy 21. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Procedure‐related complications of rapid amniodrainage in the treatment of polyhydramnios
Authors: Leung W. C. , Jouannic J.‐M. , Hyett J. , Rodeck C. , Jauniaux E.
Published: February 2004

Objective

To investigate the procedure‐related complications of rapid amniodrainage in the treatment of polyhydramnios.

Methods

We followed prospectively all patients with polyhydramnios treated with rapid amniodrainage under continuous ultrasound guidance using a vacuum wound‐drainage system from 1995 to 2002 in the fetal medicine unit of a university teaching hospital. We recorded: maternal age, type of pregnancy (singleton/twin), cause of polyhydramnios, gestational age at amniocentesis, volume of amniotic fluid drained, duration of the procedure, other intrauterine procedures in addition to the amniodrainage, and procedure‐related complications including placental abruption, premature rupture of membranes (PROM), chorioamnionitis, fetal bradycardia and preterm delivery within 48 h of amniodrainage.

Results

Seventy‐four consecutive women had 134 rapid amniodrainage procedures during the study period. Four procedures were excluded because the women were already in labor at the time of amniodrainage and they delivered within 48 h of the procedure. The final database therefore consisted of 70 patients with 130 procedures. Sixty‐two percent (80/130) of the procedures were performed for the treatment of twin–twin transfusion syndrome (TTTS). There were altogether four procedure‐related complications (3.1%; 95% CI, 1.0–8.0%). Three of them occurred in the TTTS group (3/80 procedures, 3.8%; 95% CI, 1.0–11.0%): one case each of placental abruption, PROM and fetal bradycardia. One PROM occurred in the non‐TTTS group (1/50 procedures, 2.0%; 95% CI, 0–11.0%). In both cases of PROM the women presented in labor.

Conclusions

Rapid amniodrainage using a vacuum wound‐drainage system is safe and efficient to treat severe polyhydramnios, with a 3.1% complication rate. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.