bluuebunny/crossref_metadata_2025 huggingface dataset:
An examination of outcome measures to assess functional mobility in childhood survivors of osteosarcoma
Authors: Marchese Victoria G. , Ogle Susan , Womer Richard B. , Dormans John , Ginsberg Jill P.
Published: December 2003

Background

The purpose of this study is to examine outcome measures that assess functional mobility in adolescent survivors of osteosarcoma. We will also identify relationships between functional mobility measurements and specific measure(s) of health‐related quality of life (HRQL).

Methods

Eighteen adolescent survivors of osteosarcoma at least 2 years from surgery at the Children's Hospital of Philadelphia (CHOP) participated in this study. Functional mobility, endurance, perceived exertion, and locomotor efficiency is examined with the following measurement tools: timed up and go (TUG), timed up and down stairs (TUDS), 9‐min run‐walk, rate of perceived exertion (RPE), and physiological cost index (PCI). The currently used evaluation of function from the American Musculoskeletal Tumor Society (MSTS) is also administered. The Short Form 36 (SF‐36) measuring HRQL is used.

Results

MSTS scores did not correlate with quantitative functional outcome measures. MSTS scores did not correlate with the HRQL as measured by the SF‐36. In contrast, subjects with a higher rate of vitality on the SF‐36 walked with more efficiency, farther distance during the 9‐min run‐walk, and performed the TUDS and TUG with a faster speed.

Conclusions

The MSTS does not correlate with actual measures of function or with HRQL. These data demonstrate the need for a new measure to determine functional mobility in survivors of osteosarcoma. © 2003 Wiley‐Liss, Inc.
Hydrogen‐bonding interaction of an alternating maleic acid–vinyl acetate copolymer with poly(ethylene glycol), polyacrylamide and poly(N‐isopropylacrylamide): a comparative study
Authors: Vasile C , Bumbu GG , Mylonas Y , Cojocaru I , Staikos G
Published: December 2003

The hydrogen‐bonding interaction and interpolymer complex formation between an alternating maleic acid–vinyl acetate copolymer, (MAc‐alt‐VA) and poly(ethylene glycol) (PEG), polyacrylamide (PAM) or poly(N‐isopropylacrylamide) (PNIPAM) in aqueous solution was potentiometrically and viscometrically investigated. MAc‐alt‐VA formed with PEG a strong hydrogen‐bonding interpolymer complex with a compact structure, and while its interaction with PAM seems to be very weak, if any, the complex formed with PNIPAM is even stronger than that with PEG. This indicates a very important contribution of hydrophobic interaction to the formation of such hydrogen‐bonding interpolymer complexes. Copyright © 2003 Society of Chemical Industry
Thermal properties, structure and morphology of PEEK/thermotropic liquid crystalline polymer blends
Authors: Naffakh Mohammed , Gómez Marián A , Ellis Gary , Marco Carlos
Published: December 2003

The dynamic crystallization and subsequent melting behaviour of poly(aryl ether ether ketone), PEEK, and its blends with a thermotropic liquid crystalline polymer, Vectra®, have been studied using differential scanning calorimetry, optical microscopy and wide‐angle and small‐angle X‐ray diffraction (WAXS and SAXS) techniques in a wide compositional range. Differences in crystallization rates and crystallinities were related to the structural and morphological characteristics of the blends measured by simultaneous real‐time WAXS and SAXS experiments using synchrotron radiation and optical microscopy. The crystallization process of PEEK in the blends takes place in the presence of the nematic phase of Vectra and leads to the formation of two different crystalline families. The addition of Vectra reduces the crystallization rate of PEEK, depending on composition, and more perfect crystals are formed. An increase in the long period of PEEK during heating was generally observed in the blends at all cooling rates. Copyright © 2003 Society of Chemical Industry
Preparation of a starch‐graft‐acrylamide/kaolinite superabsorbent composite and the influence of the hydrophilic group on its water absorbency
Authors: Wu Jihuai , Wei Yuelin , Lin Jianming , Lin Songbai
Published: December 2003

A novel starch‐graft‐acrylamide/kaolinite superabsorbent composite with water absorbency 4000 times (g $\rm{g}_{\rm sample}^{-1})$) was synthesized by a graft copolymerization reaction among acrylamide, potato starch and kaolinite ultrafine powder, followed by saponification with NaOH. The influence of the hydrophilic group on water absorbency was investigated. It was found that the combined absorbent effect of —CONH2, —COONa and —COOH groups was superior to that of a single group, and the composite with the molar ratio of 8:6:3 for the —CONH2, —COONa and —COOH groups exhibits the highest water‐absorbent ability. Copyright © 2003 Society of Chemical Industry
A statistical study of poly(ε‐caprolactone) crystallinity in poly(ε‐caprolactone)–silica sol–gel materials and their in vitro calcium phosphate‐forming ability
Authors: Eglin David , Ali Saad AM , Perry Carole C
Published: December 2003

Composite poly(ε‐caprolactone) (PCL)–silica materials for potential use in orthopaedic applications have been prepared by a sol–gel method using an experimental design approach to investigate the effect of synthesis variables, separately and together, on the physical form of the organic polymer. A combination of differential scanning calorimetry, X‐ray diffraction and Fourier‐transform infrared methods were used to obtain information on the arrangement of the organic polymer in the hybrid material. As our studies investigated the effect of synthesis variables simultaneously, it was possible to establish that the increase of tetraethyl orthosilicate (TEOS)/PCL and HCl/TEOS molar ratios decreased the poly(ε‐caprolactone) crystallinity and provided for a better mixing of the two phases. At a mechanistic level it was possible to show that increase in catalyst content affected the condensation of silicon containing species. In vitro calcium phosphate‐forming ability tests using the static biomimetic method have been carried out on selected PCL–silica sol–gels. In vitro bioactivity was only observed for PCL–silica sol–gel composites with high silica content (30% weight). Changes in catalyst levels had a smaller but still significant effect. Calcium phosphate formation on largely non‐porous surfaces is proposed to occur via the formation of a silica sol–gel layer, and is influenced by the topography and the chemistry of the materials surface. Copyright © 2003 Society of Chemical Industry
A study of the influence of controlled corona treatment on UHMWPE fibres in reinforced vinylester composites
Authors: Zheng Zhen , Tang Xiaozhen , Shi Meiwu , Zhou Guotai
Published: December 2003

In order to illuminate the mechanisms of corona discharge treatment on ultra‐high molecular weight polyethylene (UHMWPE) fibre, the effects of corona treatment power and time are discussed in detail. The surface‐roughness and tensile‐failure characteristics of the polyethylene fibre were determined by a scanning electron microscope (SEM). The photos from the SEM showed that the size and number of the micro‐pits on the fibre surface increase with increase of corona power. The oxygen‐containing groups on the fibre surface could be detected by Fourier‐transform infrared attenuated total reflectance and also increased gradually with increase of corona power. The T‐peel strength of composites increased from the corona treatment, and then showed a maximum value at a corona treatment time about 0.1 s with increase of treatment time. However, the tensile strength of the fibre was reduced with increase of corona power and the failure mechanism obviously changed after the treatment. The ballistic impact energy absorption of UHMWPE fibre/vinylester composite was obtained after fragment simulating projectiles (FSP) impact tests. After 6‐kW corona treatment for 0.075 s, the impact energy absorbed by the laminate reached a maximum value. Copyright © 2003 Society of Chemical Industry
Crystallization kinetics and morphology of binary phenolic/poly(ϵ‐caprolactone) blends
Authors: Kuo Shiao‐Wei , Chan Shih‐Chi , Chang Feng‐Chih
Published: December 2003

For the first time, quantitative analyses of the crystallization kinetics, surface free energy of chain folding, and morphology in phenolic/poly(ϵ‐caprolactone) (PCL) binary blends have been studied. The spherulite growth rate and the overall crystallization rate depend on the crystallization temperature and PCL content in the blend. In addition, the crystallization and melting temperatures of the PCL phase decrease with an increase in the phenolic content. An Avrami analysis shows that the addition of phenolic to PCL results in a decrease in the overall crystallization rate of the PCL phase. The presence of an amorphous phenolic phase results in a reduction in the rate of the spherulite growth of PCL. The surface free energy of folding increases with increasing phenolic content, and the crystal thickness of a phenolic/PCL blend, according to small‐angle X‐ray scattering (SAXS), is greater than that of pure PCL because of the increase in the surface free energy of chain folding and the decrease in the degree of supercooling. The observed domain size of the crystalline/amorphous phase (5.9 nm) from SAXS is also consistent with that from solid‐state NMR (3–20 nm). All these results indicate that the crystallization ability of PCL decreases with increasing phenolic content in the blends. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 117–128, 2004
Thermal analysis of the double‐melting behavior of poly(L‐lactic acid)
Authors: Yasuniwa Munehisa , Tsubakihara Shinsuke , Sugimoto Youhei , Nakafuku Chitoshi
Published: December 2003

The melting and crystallization behavior of poly(L‐lactic acid) (PLLA; weight‐average molecular weight = 3 × 105) was studied with differential scanning calorimetry (DSC). DSC curves for PLLA samples were obtained at various cooling rates (CRs) from the melt (210 °C). The peak crystallization temperature and the exothermic heat of crystallization determined from the DSC curve decreased almost linearly with increasing log(CR). DSC melting curves for the melt‐crystallized samples were obtained at various heating rates (HRs). The double‐melting behavior was confirmed by the double endothermic peaks, a high‐temperature peak (H) and a low‐temperature peak (L), that appeared in the DSC curves at slow HRs for the samples prepared with a slow CR. Peak L increased with increasing HR, whereas peak H decreased. The peak melting temperatures of L and H [Tm(L) and Tm(H)] decreased linearly with log(HR). The appearance region of the double‐melting peaks (L and H) was illustrated in a CR–HR map. Peak L decreased with increasing CR, whereas peak H increased. Tm(L) and Tm(H) decreased almost linearly with log(CR). The characteristics of the crystallization and double‐melting behavior were explained by the slow rates of crystallization and recrystallization, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 25–32, 2004
Synthesis and isodimorphic cocrystallization behavior of poly(1,4‐cyclohexylenedimethylene terephthalate‐co‐1,4‐cyclohexylenedimethylene 2,6‐naphthalate) copolymers
Authors: Jeong Young Gyu , Jo Won Ho , Lee Sang Cheol
Published: December 2003

A series of poly(1,4‐cyclohexylenedimethylene terephthalate‐co‐1,4‐cyclohexylenedimethylene 2,6‐naphthalate) [P(CT‐co‐CN)] copolymers were synthesized, and their cocrystallization behavior was investigated using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD). Although the P(CT‐co‐CN) copolymers synthesized have statistical random distribution of CT and CN units, all the copolymers show clear melting and crystallization peaks in DSC thermograms over entire copolymer composition, and have an eutectic melting temperature in the plot of melting temperature versus copolymer composition. WAXD patterns of all the samples show sharp diffraction peaks, and are largely divided into two classes according to the copolymer composition, that is, PCT‐type and PCN‐type diffraction patterns. These facts lead us to conclude that P(CT‐co‐CN) copolymers show isodimorphic cocrystallization. The eutectic composition at which the crystal transition from PCT‐type to PCN‐type crystal occurs was estimated ca. 40 mol % CN content. When the defect Gibbs free energy was estimated by using the equilibrium inclusion model proposed by Wendling and Suter, the value (7.18 kJ/mol) in the case of incorporation of CT units in the PCN crystals were larger than the case (3.32 kJ/mol) of incorporation of CN units in the PCT crystals. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 177–187, 2004
Eight‐arm star polystyrene in methylcyclohexane: Cloud‐point curves, critical lines, and coexisting densities and viscosities
Authors: Alessi Michael L. , Bittner Katie C. , Greer Sandra C.
Published: December 2003

We measured the cloud‐point curves of eight‐arm star polystyrene (sPS) in methylcyclohexane (MCH) for polymer samples of three total molecular masses [weight‐average molecular weight (Mw) × 10−3= 77, 215, or 268]. We found a downward shift of 5–15 K in the critical temperature (Tc) of the star polymer solutions with respect to linear polystyrene (PS) solutions of the sameMw. The shift inTcbecame smaller asMwincreased. The critical volume fraction for eight‐arm sPS in MCH was equal within experimental uncertainty (10–40%) to that of linear PS in MCH. For sPS ofMw= 77,000 in MCH, we studied the mass density (ρ) as a function of temperature (T). As for linear polymers in solution, the difference in ρ between coexisting phases (Δρ) could be described overt= (Tc−T)/Tcfor 1.1 × 10−4<t< 4.7 × 10−3with the Ising value of the exponent β in the expression Δρ =Btβ. Both ρ(T) aboveTcand the average value of ρ belowTcwere linear functions of temperature; no singular corrections were observed. The measurements of the shear viscosity (η) nearTcfor sPS (Mw= 74,000) in MCH indicated a strong critical anomaly in η, but the data were not precise enough for a quantitative analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 129–145, 2004
Relationship between Floc Short Range Structure and Sediment Compaction
Authors: Hermawan Mandalena , Bushell Graeme , Bickert Götz , Amal Rose
Published: December 2003

This paper studies the short and long‐range structure of silica aggregates using the small angle light scattering technique. Silica particles were made to aggregate by the addition of MgCl2, with and without continuous shear. Two different short‐range structures were observed for different aggregation conditions. The small angle light scattering reveals two different floc structures at different length scales, a very compact floc at short length scale and a loose floc at large length scale. The sediments of these flocs were studied by allowing them to settle under gravity and consolidate at different centrifugal forces. The results show that the floc short‐range structure is important in governing the compaction behaviour of sediment.
Matrix‐assisted laser desorption/ionisation mass spectrometry in the study of polycondensation of Ti(OBun)4 in the presence of Si(OEt)4
Authors: Seraglia Roberta , Armelao Lidia , Cristoni Simone , Gross Silvia , Tondello Eugenio , Traldi Pietro
Published: December 2003

The hydrolysis‐polycondensation behaviour of alcoholic solutions containing Si(OEt)4 and Ti(OBun)4, in different molar ratios (Si/Ti = 10–0.2), was analysed by laser desorption/ionisation (LDI) and matrix‐assisted laser desorption/ionisation (MALDI) mass spectrometry. The solutions were prepared using operating conditions usually employed in the sol‐gel synthesis of SiO2‐TiO2 materials. In accord with the well‐known procedures for controlling the different chemical reactivities of the alkoxides, the pre‐hydrolysis of the slower reacting silicon ethoxide and the chelation by acetylacetone of the faster reacting titanium butoxide were performed before mass spectrometric analysis. While LDI‐MS did not provide evidence for the presence of mixed Si‐Ti species in samples obtained from these reactions, MALDI‐MS of samples diluted with chloroform and using 2,5‐dihydroxybenzoic acid (DHB) as matrix led to detection of various oligomers with different contents of Si and Ti atoms. The results suggest that the formation of Si‐Ti mixed oligomers seems to be the favoured process, especially for solutions in which one of the two components is diluted. Copyright © 2003 John Wiley & Sons, Ltd.
High accuracy method for the application of isotope dilution to gas chromatography/mass spectrometric analysis of gases
Authors: Milton Martin J. T. , Wang Jian
Published: December 2003

A new isotope dilution mass spectrometry (IDMS) method for high‐accuracy quantitative analysis of gases has been developed and validated by the analysis of standard mixtures of carbon dioxide in nitrogen. The method does not require certified isotopic reference materials and does not require direct measurements of the highly enriched spike. The relative uncertainty of the method is shown to be 0.2%. © Crown copyright 2003. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
Deviation inequality for monotonic Boolean functions with application to the number of k‐cycles in a random graph
Authors: Panchenko Dmitry
Published: December 2003

Using Talagrand's concentration inequality on the discrete cube {0, 1}m we show that given a real‐valued function Z(x) on {0, 1}m that satisfies certain monotonicity conditions one can control the deviations of Z(x) above its median by a local Lipschitz norm of Z at the point x. As one application, we obtain a deviation inequality for the number of k‐cycles in a random graph. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 2004
On the capacity optimization in multicarrier channel operation
Authors: Pujante‐Cuadrupani Antonio , de Haro‐Ariet Leandro
Published: December 2003

The transmission plan for a communications channel exploited in multicarrier mode involves the operational parameters and the prediction of the channel impairments with special consideration for the intermodulation noise generated by beating among carriers. The intermodulation noise is a driving factor in the design phase of a transmission plan as it seriously affects the C/N + 1 ratio of the carriers in the channel, being often the dominant factor.

The transmission plan of a channel operated in multicarrier mode can be represented as an injective application between two sets: the carriers and the frequency slots of the channel. Classical combinatory laws allow for the prediction of the number of configurations that can be established with sets of unidimensional elements. However, if one of the sets has elements with non‐unidimensional attributes, the classical combinatory laws fail to predict the number of possible configurations. This is the case in multicarrier transmission plans, where the carriers have an associated bandwidth (attribute of the carrier) that typically occupy several frequency slots. In this paper, an expression for the prediction of the number of possible configurations in a transmission plan is derived. This expression permits to select the most appropriate method to achieve transmission plan optimization, as a function of the associated computational resources.

The higher the number of configurations, the higher the options for the optimization of the transmission plan. Subsequently, the C/N + I ratio of the carriers can be increased and therefore the quality of the service and the use of the channels resources are improved. Investigation of the space of configurations show that the maximum number of possible configurations is achieved in the range of 70–90% of channel occupation, which converges with the typical operational use of satellite transponders in multicarrier operation.

This discussion is applicable not only to the frequency domain but also to any other system where sets of elements with non‐unidimensional attributes have to be considered (time domain, space domain, etc.). Copyright © 2003 John Wiley & Sons, Ltd.
Performance limitation of laser satellite communication due to vibrations and atmospheric turbulence: down‐link scenario
Authors: Arnon S. , Kopeika N. S. , Kedar D. , Zilberman A. , Arbel Dan , Livne A. , Guelman M. , Orenstain M. , Michalik H. , Ginati A.
Published: December 2003

In this paper, we analyse the effects of vibrations and the atmosphere on the performance of a broadband laser inter‐satellite link (BLISL) which was studied within the framework of the BLISL joint Israeli–German applied research project. The use of optical radiation as a carrier between satellites and in satellite‐to‐ground links enables transmission using very narrow beam divergence angles. Due to the narrow beam divergence angle and the large distance between the satellite and the ground station or airplane the pointing is a complicated process. Further complication results from vibration of the pointing system caused by two fundamental mechanisms of a stochastic nature: (1) tracking noise created by the electro‐optic tracker and (2) vibrations caused by internal satellite mechanical mechanisms. Additionally an inhomogeneity in the temperature and pressure of the atmosphere leads to variations of the refractive index along the transmission path. These variations of refractive index as well as pointing vibrations can cause fluctuations in the intensity and the phase of the received signal leading to an increase in link error probability. In this paper, we develop a bit error probability (BEP) model that takes into account both pointing vibrations and turbulence‐induced log amplitude fluctuations (i.e. signal intensity fading) in a regime in which the receiver aperture D0 is smaller than the turbulence coherence diameter d0. Our results indicate that BLISL can achieve a BEP of 10−9 and data rate of 1Gbps with normalized pointing vibration of GT*σθ2=0.05 and turbulence of σX=0.3. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of growth curves via mixtures
Authors: Rosen Ori , Cohen Ayala
Published: December 2003

We present a method for analysing growth curves using the mixtures‐of‐experts (ME) approach, which enables flexible estimation of the dependence of height on age. Individual growth curves are first fitted and the resulting estimates are then pooled to facilitate the estimation of mean growth curves, velocity and acceleration of growth and centile curves. The method allows for comparisons between males and females. We illustrate our methodology with data on growth of male and female children (0–4 years old). Copyright © 2003 John Wiley & Sons, Ltd.
Simple procedures for blinded sample size adjustment that do not affect the type I error rate
Authors: Kieser Meinhard , Friede Tim
Published: December 2003

For normally distributed data, determination of the appropriate sample size requires a knowledge of the variance. Because of the uncertainty in the planning phase, two‐stage procedures are attractive where the variance is reestimated from a subsample and the sample size is adjusted if necessary. From a regulatory viewpoint, preserving blindness and maintaining the ability to calculate or control the type I error rate are essential. Recently, a number of proposals have been made for sample size adjustment procedures in the t‐test situation. Unfortunately, none of these methods satisfy both these requirements. We show through analytical computations that the type I error rate of the t‐test is not affected if simple blind variance estimators are used for sample size recalculation. Furthermore, the results for the expected power of the procedures demonstrate that the methods are effective in ensuring the desired power even under initial misspecification of the variance. A method is discussed that can be applied in a more general setting and that assumes analysis with a permutation test. This procedure maintains the significance level for any design situation and arbitrary blind sample size recalculation strategy. Copyright © 2003 John Wiley & Sons, Ltd.
Use of incomplete post‐treatment data in the analysis of viral eradication studies
Authors: Cheng Debbie M. , Lagakos Stephen W.
Published: December 2003

In some studies of chronic viral infections where the objective is to estimate the distributions of time until viral eradication and viral resistance to treatment, patients must have treatment terminated in order to assess eradication status. Such patients then have their viral load continually monitored during a post‐treatment period. If no virus is detected during this period, viral eradication is presumed to have occurred whereas detection of virus is interpreted to mean that the virus had been suppressed but not eradicated prior to treatment interruption. If the post‐treatment period is long, as would be the case with diseases such as hepatitis C and HIV, there will be patients who have not completed the post‐treatment period by the time the data are analysed. This paper proposes non‐parametric and semi‐parametric methods to incorporate partial post‐treatment data in the estimation of the subdistributions of the time until eradication and resistance. The new methods extend previous methods for the analysis of eradication studies that do not account for incomplete post‐treatment information, and are illustrated with data from a recent hepatitis C clinical trial. Copyright © 2003 John Wiley & Sons, Ltd.
Qualitative simulation of models of software evolution
Authors: Ramil Juan F. , Smith Neil
Published: December 2003

Lehman's laws and the quantitative models based on them seek to encapsulate empirical generalizations about E‐type program evolution. Such modelling is hampered by insufficient knowledge about the mechanisms at work and their parameters. Qualitative reasoning is a body of work that handles a lack of precise knowledge by reasoning at a more abstract level than with quantitative models. This paper describes the introduction of qualitative reasoning to the study of software evolution. It reports on the derivation of qualitative versions of two existing quantitative models of the software evolution process, leading to identification of previously unrecognized behaviours. A third qualitative model is also discussed. The paper also shows how qualitative trend abstraction enables a high level of abstraction analysis of empirical data and that, at this level, the empirical patterns observed in several different software systems display similarities. Finally, we compare the qualitative simulation outputs of the three systems to the abstracted empirical trends. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluating the sustained performance of COTS‐based messaging systems
Authors: Tran Phong , Gosper Jeffrey , Gorton Ian
Published: December 2003

Messaging systems, which include message brokers built on top of message‐oriented middleware, have been used as middleware components in many enterprise application integration projects. There are many COTS‐based messaging systems on the market, but there is little concrete understanding in the software industry on the performance of these different technologies. The authors have carried out a scenario‐based evaluation of three leading messaging systems to provide insight into performance issues. The evaluation process includes a study of the sustained performance of the system under load. The result of this study is used to derive a generic metric for quantifying a messaging system's performance. The paper describes a synthetic transactional scenario, which is used for load tests and performance measurement. The results from executing this test scenario with three messaging systems are then presented and explained. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluating online control of goal‐directed arm movement while standing in virtual visual environment
Authors: Martin Olivier , Julian Benjamin , Boissieux Laurence , Gascuel Jean‐Dominique , Prablanc Claude
Published: December 2003

It has been shown that an inaccurate motor planning of a fast goal‐directed movement could be amended through an online comparison between the goal and the instantaneous representation of the (unseen) moving hand. The aim of this study was to test whether such an optimum processing was still efficient in a virtual visual environment (VE), by exploring the effect of immersion on the online visuomotor control of goal‐directed arm movement. Six subjects participated in the experiment, in which hand reaching toward either a stationary or a moving virtual visual target (double‐step paradigm) was executed in an upright posture. The analysis of the hand kinematics and postural adjustments showed an accurate control of movement and balance in both reaching conditions. This indicates that immersion does not affect the online control processes used by the CNS to adjust movement in interactive VE. Copyright © 2003 John Wiley & Sons, Ltd.
Third generation WCDMA radio evolution
Authors: Holma Harri , Toskala Antti
Published: December 2003

Third Generation Partnership Project (3GPP) produced the first full version of the WCDMA standard at the end of 1999. This release, called Release'99, contains all the necessary elements to meet the requirements for IMT‐2000 technologies, including 2 Mbps data rate with variable bit‐rate capability, support of multi‐service, QoS differentiation and efficient packet data. The Release 5 specifications were created in March 2002 and they contain downlink packet data operation enhancement, under the title high speed downlink packet access (HSDPA). HSDPA utilizes Hybrid ARQ and higher order modulation for improving data‐spectral efficiency and for pushing bit rates beyond 10 Mbps. The further 3GPP releases will study the enhancements of packet‐data performance in uplink. Other important features in future 3GPP releases include advanced antenna technologies and WCDMA standard for new spectrum allocations. The paper describes the main solutions of 3GPP WCDMA standard in more detail. Copyright © 2003 John Wiley & Sons, Ltd.
Pilot pollution interference cancellation in CDMA systems
Authors: El‐Said Mostafa M. , Kumar Anup , Elmaghraby Adel S.
Published: December 2003

In CDMA systems, existence of large number of equally strong pilot signals is not desirable. As a consequence, this would create pilot pollution interference (PPI). Additionally, the limited number of fingers in the RAKE receiver adds a different dimension to the problem. The PPI has the influence of overloading the mobile station's RAKE receiver with excessive amount of signaling on the dedicated control channels. Therefore, the pilot signal's orthogonality erodes dramatically, and the system suffers from dropping of ongoing calls, blocking of originating fresh calls and decrease in the system capacity. In this paper, we demonstrate the power of using a novel multi‐carrier chip shaping to alleviate the impact of the PPI. Consequently, the mobile's RAKE receiver will have the capability to perform frequency diversity rather than multipath diversity. This will make efficient use of the received signal energy in the frequency domain and boost the performance of the system. Simulation studies have been carried out to verify the appropriateness of the proposed approach and we have obtained very promising results. Copyright © 2003 John Wiley & Sons, Ltd.
UMTS architecture extension to adapt multimedia services and manage their flow properties
Authors: Sfar Safouane , Choukair Zièd
Published: December 2003

Our approach exposed in this paper consists of providing an end‐to‐end adaptation frame to UMTS REL.99 (UMTS Release 1999, first phase of UMTS) commercial services, according to a virtual home environment (VHE) context. A commercial service provided to the user should be adapted during its selection as well as during its transfer through the different parts of the network. These adaptations are due to the fluctuation of the parameters of the network and the need to adapt the quality of service (QoS) parameters. The four steps of adaptation we will develop in our model will be guaranteed by ‘adaptation bearer service (ABS)’. An ABS will provide, for example, data encoding or data compression. ABS differs according to the localization and the adaptation mode. In this paper, we present also our adaptation strategy and associated policies. The purpose of this strategy is to classify and then select service flows which are to be adapted in priority. Policies are specified according to factors that we defined. Fuzzy logic is used for the implementation of this strategy as it represents a natural reasoning mode useful to decide which commercial service adaptation policy is to be carried out according to resource use context. Copyright © 2003 John Wiley & Sons, Ltd.
A throughput‐efficient and channel‐adaptive scheduling scheme in voice/data DS‐CDMA networks with transmission power constraints
Authors: Shu Tao , Niu Zhisheng
Published: December 2003

In a practical voice/data CDMA network, the constraint of transmission powers makes it necessary to transmit multiple data users in parallel in order to fully utilize system resource (power). How to choose those data users that should be transmitted simultaneously and allocate appropriate powers among them remains an open issue. In this paper, we prove that it is optimal in the sense of maximum data throughput to select data users and allocate powers according to the descending order of their indexes of received power capability (IRPC). Here, IRPC is defined as the product of the transmission power upper bound and the channel gain. based on this principle, a channel‐adaptive scheduling scheme, partially descending IRPC (PDI) scheduling, is proposed to achieve efficient throughput performance for data traffic while maintaining certain fairness among different users. The efficiency and fairness of the PDI scheduling are verified by comparing with the conventional fair‐sharing scheme and round‐robin scheme through computer simulations. Numerical results also reveal the robustness of the new scheme to the channel estimation errors. Copyright © 2003 John Wiley & Sons, Ltd.
Sampling Bias on Cup Anemometer Mean Winds
Authors: Kristensen L. , Hansen O. F. , Højstrup J.
Published: December 2003

The cup anemometer signal can be sampled in several ways to obtain the mean wind speed. Here we discuss the sampling of series of mean wind speeds from consecutive rotor rotations, followed by unweighted and weighted averaging. It is shown that the unweighted averaging creates a positive bias on the long‐term mean wind speed, which is at least one order of magnitude larger than the positive bias from the weighted averaging, also known as the sample‐and‐hold method. For a homogeneous, neutrally stratified flow the first biases are 1%–2%. For comparison the biases due to fluctuations of the three wind velocity components and due to calibration non‐linearity are determined under the same conditions. The largest of these is the v‐bias from direction fluctuations. The calculations pertain to the Risø P2546A model cup anemometer. Copyright © 2003 John Wiley & Sons, Ltd.
Nitrogen Rich Materials: Salts of N, N′‐Bistetrazolatohydrazine
Authors: Hammerl Anton , Holl Gerhard , Kaiser Manfred , Klapötke Thomas M. , Piotrowski Holger
Published: December 2003

Solutions of N, N′‐azobistetrazolate salts in anhydrous hydrazine were reduced to salts of N, N′‐bistetrazolatohydrazine. Several salts of this highly energetic, nitrogen rich anion were prepared this way and characterized by elemental analysis, vibrational (IR, Raman) and multinuclear NMR spectroscopy (1H, 13C, 14N). The crystal structure of the barium and hydrazinium salt were determined.
Funktionalisierte β‐Hydroxydithiozimtsäurederivate als Liganden. Kristallstrukturanalyse von 4′‐Hydroxy‐β‐hydroxydithiozimtsäuremethylester
Authors: Schubert Karsten , Saumweber Rupert , Görls Helmar , Weigand Wolfgang
Published: December 2003

Aus silylgeschütztem 4′‐Hydroxyacetophenon (1) entsteht durch Umsetzung mit Schwefelkohlenstoff und Iodmethan in Gegenwart von Kalium‐tert‐butylat der silylsubstituierte 4′‐Hydroxy‐β‐hydroxydithiozimtsäuremethylester (2). Die Molekülstruktur des nach Abspaltung der Schutzgruppe entstehenden Esters 3 wurde durch Röntgenstrukturanalyse bestimmt. Die phenolische OH‐Gruppe wird mit DL‐α‐Liponsäure (4) verestert. Der so zugängliche 4′‐(1, 2‐Dithiolan‐3‐pentanoyl)‐β‐hydroxydithiozimtsäuremethylester (5) bildet mit NiII, PdII und PtII Komplexe.
Strukturelle Modellierung der Alkoholdehydrogenase: Zinkkomplexe von Acetyl‐ und Benzoylpyridin
Authors: Schneider Astrid , Vahrenkamp Heinrich
Published: December 2003

Die N, O‐Chelatliganden Acetyl‐ und Benzoylpyridin (L) bilden mit Zinkchlorid fünf‐ und sechsfach koordinierte Komplexe der Zusammensetzungen L2ZnCl2 und [L2ZnCl]+. Mit den Zinkthiolaten des Pentafluorthiophenols und 2, 4, 6‐triisopropylthiophenols entstehen dagegen tetraedrische Komplexe der Zusammensetzung L˙Zn(SR)2. Diese sind strukturelle Modelle der Zn(NOS2)‐Bindungssituation bei Anbindung eines Aldehyds im aktiven Zentrum des Enzyms Alkoholdehydrogenase.
Zur Synthese von Na3FeO3, einem ternären Oxoferrat(III) mit Kettenstruktur
Authors: Sobotka Bettina M. , Möller Angela
Published: December 2003

Synthesis of Na3FeO3, a Ternary Oxoferrate(III) with a Chain Structure

Na3FeO3 has been obtained from a redox reaction between CdO and iron metal in the presence of Na2O and Na2CO3 at 650 °C as amber colored transparent single crystals. The crystal structure determination (IPDS data: P21/n, a = 579.9(1) pm, b = 1265.9(2) pm, c = 582.8(1) pm, β = 116.02(2)°, Z = 4, Rall = 0.0576) reveals the presence of [FeO2O2/2] zig‐zag‐chains.
Zwei Cer(III)‐Chlorid‐Oxoborate im Vergleich: Ce3Cl3[BO3]2 und CeCl(BO2)2
Authors: Nikelski Tanja , Schleid Thomas
Published: December 2003

Kristalle der Zusammensetzung Ce3Cl3[BO3]2 werden durch Umsetzung von CeO2, elementarem Cer, CeCl3 und B2O3 mit einem Überschuß an CeCl3 als Flußmittel bei 550 °C in gasdicht verschweißten Platinampullen innerhalb von drei Wochen erhalten. Einkristallines CeCl(BO2)2 entsteht ebenfalls bei der Umsetzung von CeO2, elementarem Cer, CeCl3 und B2O3, allerdings im Überschuß von B2O3 als Flußmittel, in einer verschlossenen Platinampulle nach zwei Wochen bei 900 °C. Beide Verbindungen kristallisieren in Form von langen, dünnen, transparenten, farblosen, luft‐ und wasserbeständigen Nadeln. Die Kristallstruktur von Ce3Cl3[BO3]2 (hexagonal, P63/m; a = 920, 08(6); c = 580, 79(4) pm; Z = 2) zeigt strukturelle Ähnlichkeiten mit CeCl3 (UCl3‐Ty p), indem man Cl‐‐Anionen partiell gegen [BO3]3‐‐Gruppen austauscht. Ce3Cl3[BO3]2 ist aus planaren Schichten, die aus isolierten Oxoborat‐Einheiten [BO3]3‐ einerseits und aus Ce3+‐Kationen sowie Cl‐‐Anionen andererseits bestehen, aufgebaut. Das Ce3+‐Kation weist eine Koordinationszahl von zehn auf, wobei es sich mit sechs O2‐‐ und vier Cl‐‐Anionen vierfach‐überkappt trigonal‐prismatisch umgibt. CeCl(BO2)2 kristallisiert analog MCl(BO2)2 (M = La, Pr) triklin in der Raumgruppe P1¯ (a = 421, 74(5); b = 657, 63(7); c = 812, 21(9) pm; α = 82, 152(6); β = 89, 206(7); γ = 72, 048(6)°; Z = 2). Die charakteristische Baueinheit besteht aus unendlichen Ketten {[(B1)O1/1tO2/2e(B2)O1/1tO2/2e]2‐} (≡ {[BO2]‐}) eckenverknüpfter [BO3]3‐‐Dreiecke. Diese Einheiten sind derart verknüpft, daß zickzack‐förmige Stränge entstehen, die entlang [100] verlaufen. Das Ce3+‐Kation ist ebenfalls von zehn Anionen (sieben O2‐ und drei Cl‐) in Form eines Edshammar‐Polyeders koordiniert.
Synthesis, Crystallographic Studies, and Characterization of K2Bi8Se13—xSx Solid Solutions
Authors: Kyratsi Theodora , Kanatzidis Mercouri G.
Published: December 2003

The detailed crystal structures of selected members of solid solutions of the thermoelectric compounds K2Bi8Se13—xSx with x = 4, x = 6 and x = 10 were determined. The purpose of this study was to understand the nature of Se/S mass fluctuations introduced when β‐K2Bi8Se13 is alloyed with isostructural K2Bi8S13. The details of the K/Bi disorder and Se/S distribution are examined. Lattice parameters, semiconducting band gaps and melting points are reported as function of x.
La4Br2Al5 and Ce4Br2Ga5: Three‐dimensional Metal Networks Embedded in Condensed Ln6 Trigonal Prisms
Authors: Zheng Chong , Mattausch Hansjürgen , Oeckler Oliver , Nuss Jürgen , Simon Arndt
Published: December 2003

La4Br2Al5 and Ce4Br2Ga5 are metal‐rich and feature Al or Ga centered Ln6 (Ln = La, Ce) trigonal prisms. The packing of these prisms is unique and characterizes a new variation in reduced rare‐earth halides. The prisms fuse into dimeric units which in turn form rectangles parallel to the a‐b plane. They then stack in the [0 0 1] direction, creating channels along the c‐axis. The halides occupy these channels, while Al or Ga atoms join to a three‐connected, three‐dimensional network encircling these channels. The title compounds represent a new structure type, crystallizing in the space group Cmmm (No. 65) with lattice constants a = 16.115(3) and 15.796(3)Å, b = 17.206(3) and 16.795(3), c = 4.3280(9) and 4.2344(8)Å, respectively for La4Br2Al5 and Ce4Br2Ga5. An isostructural, however nonstoichiometric and disordered phase La4.15Br2Ga4.69 also exists with a = 15.902(1)Å, b = 17.034(1)Å, and 4.2612(3)Å. Computational analysis reveals that they belong to the class of reduced valence rare‐earth halides. However, because of the extended interaction between Ln and M, the conduction band of these compounds is partially occupied. Conductivity and magnetic susceptibility measurements confirm the metallic nature of these compounds, and reveal Cerium to be trivalent as expected.
Cyclopentadienyl(diamino)boranes and their Derivatives — a Family of Versatile Ligand Precursors for Constrained Geometry Complexes
Authors: Braunschweig Holger , Breitling Frank M. , Homberger Melanie , von Koblinski Carsten , White Andrew J. P. , Williams David J.
Published: December 2003

A wide range of potential ligand precursors for the preparation of boron‐bridged, constrained geometry complexes has been synthesized. These include (i) cyclopentadienyl(diamino)boranes such as (C5H5)B(NiPr2)N(H)Cy (7), (C5H5)B(NiPr2)N(H)Ph (8), and (C5H5)B{N(SiMe3)2}N(H)Ph (9); (ii) the corresponding indenyl derivatives such as (C9H7)B(NiPr2)N(H)Cy (10) and (C9H7)B{N(SiMe3)2}N(H)Cy (11); and (iii) even bulkier derivatives, such as (C5Me4H)B{N(SiMe3)2}N(H)tBu (12), (C5Me4H)B{N(SiMe3)2}N(H)Ph (13), and (C13H9)B(NiPr2)N(H)Ph (C13H9 = fluorenyl) (14). All compounds have been characterised by multinuclear NMR spectroscopy and mass spectrometry, and in the case of 14 by X‐ray diffraction.
Synthesis, Structure and Solution Chemistry of (5, 5′‐Dimethyl‐2, 2′‐bipyridine)(IDA)copper(II) and Structural Comparison With Aqua(IDA)(1, 10‐phenanthroline)copper(II) (IDA = iminodiacetato)
Authors: Craven Emma , Zhang Cungen , Janiak Christoph , Rheinwald Gerd , Lang Heinrich
Published: December 2003

The protolytic equilibria of copper(II), 5, 5′‐dimethyl‐2, 2′‐bipyridine (bpy) and iminodiacetate (IDA) have been investigated by potentiometric titration between pH 2 and 8. Potentiometric titration suggests the presence of [Cu(IDA)(bpy)]0 at a fraction of 28 % of all copper species in solution at pH 8 with a stability constant logβ = 13.9. The crystal structures of [Cu(IDA)(bpy)] · 4H2O (1) and [Cu(IDA)(H2O)(phen)] · 4H2O (2) show the IDA ligand coordinated in the fac‐NO+O mode. The structure of 1 features “dimeric” entities of symmetry‐independent five‐coordinated Cu‐complexes through a long Cu···O contact, hydrogen bonding and π‐stacking, including a “pyridyl—metal‐chelate ring” π‐contact as evidence for metalloaromaticity in aromatic α, α′‐diimine‐copper(II) chelates. The structure of 2 has the tetragonally six‐coordinated molecular Cu‐complexes arranged by hydrogen bonding and π‐stacking. The crystal water in 2 forms infinite corrugated double chains composed of alternating four‐ and six‐membered, edge‐sharing rings of hydrogen‐bonded water molecules.
Gezielte Synthese und Struktur eines oxamid‐verbrückten Nitroxid‐tetraradikal‐dipalladium‐Komplexes
Authors: Sommer Christian , Ponikwar Walter , Ponikwar Werner , Nöth Heinrich , Beck Wolfgang
Published: December 2003

Die Reaktion des chloroverbrückten, orthopalladierten Bis(2, 2, 5, 5‐tetramethyl‐4‐phenyl‐2, 5‐dihydroimidazolin‐1‐oxyl) mit dem Oxalsäurediamid‐verbrückten Bis(tetramethylpiperidin‐oxyl) (1) liefert einen Tetranitroxiddipalladium‐Komplex 3 mit einer Oxamid‐Brücke in der trans‐Konformation, der röntgenographisch charakterisiert wurde und einen weitgehend planaren Bau hat. Auch die Struktur des Dinitroxids 1 wurde durch Röntgenbeugung bestimmt: Sie ist durch zwei intramolekulare Wasserstoffbrücken‐Bindungen zwischen den Oxalsäureamid NH und CO Gruppen festgelegt. Das Dinitroxid 1 ergibt mit der chloroverbrückten Verbindung [(Cl)(Et3P)Pd(μ‐Cl)]2 einen diradikalischen Oxamid‐verbrückten Dipalladium Komplex 4.
Synthesen und Strukturen von Perfluororganohalogenomercuraten [Hg(Rf)2X]— (Rf = CF3, C6F5; X = Br, I)
Authors: Schulz Frank , Pantenburg Ingo , Naumann Dieter
Published: December 2003

Bei den Umsetzungen von Hg(Rf)2 (Rf = CF3, C6F5) mit [(18‐C‐6)K]X (X = Br, I) in CH2Cl2 oder H2O bilden sich die Mercurate [(18‐C‐6)K][Hg(Rf)2X] in guten Ausbeuten. Die Trifluormethylverbindungen [(18‐C‐6)K][Hg(CF3)2X] kristallisieren isotyp in der monoklinen Raumgruppe P21; die azentrische Raumgruppe wird durch Messung des optischen SHG‐Effektes bestätigt. [(18‐C‐6)K][Hg(C6F5)2Br] kristallisiert in der monoklinen Raumgruppe P21/n und [(18‐C‐6)K][Hg(C6F5)2I] in der triklinen Raumgruppe P1¯. In allen vier Kristallen liegen die Anionen monomer mit T‐förmiger Umgebung des Quecksilbers vor. Die Massenspektren sowie die thermische Stabilität der Mercurate werden beschrieben.
[Cu7] Cluster in SrCu7In6 — Synthesis and Structure Refinement of a Twinned Crystal
Authors: Zaremba Vasyl' I. , Muts Ihor R. , Hoffmann Rolf‐Dieter , Pöttgen Rainer
Published: December 2003

The intermetallic compound SrCu7In6 was synthesized by reaction of the elements in a glassy carbon crucible under flowing argon and subsequently homogenized by annealing at 670 K in an evacuated sealed quartz ampoule for one month. It was investigated by X‐ray diffraction on powders and single crystals: Pnnm, a = 1261.7(2) pm, b = 1261.7(2) pm, c = 1271.4(2) pm, wR2 = 0.1046, 2468 F2 values, 145 variables. The refinement was based on a twinned crystal. The structure constitutes a new superstructure of the cubic NaZn13 type. Indium and copper atoms are well ordered on the Zn2 position of NaZn13. They form icosahedra centered by copper atoms (Zn1 position). The copper atoms form a one‐dimensional infinite cluster chain with Cu—Cu distances ranging from 253 to 280 pm while the indium atoms make up a three‐dimensional network enveloping the copper chains. The strontium atoms occupy large cavities built up by 12 indium and 12 copper atoms. The structure‐chemical relation between the structures NaZn13, CeNi8.5Si4.5, LaNi7In6, and SrCu7In6 is discussed on the basis of a group‐subgroup relation.
Neue binäre Stannide A52Sn82 (A = K, Cs) mit Sn‐ und Sn‐Cluster‐Anionen
Authors: Hoch Constantin , Wendorff Marco , Röhr Caroline
Published: December 2003

Die Kristallstrukturen der aus den Elementen zugänglichen neuen isotypen binären Stannide A52Sn82 (A = K/Cs; monoklin, Raumgruppe P21/c, a = 2561.8(7)/ 2712.0(7), b = 1479.2(5)/1555.0(4), c = 5565.3(9)/5878.23(8) pm, Z = 4) enthalten ensprechend A52[Sn9]6[Sn4]7 zum weissen Phosphor isoelektronische und isostrukturelle Zintl‐Anionen Sn und elektronisch den Wade‐Regeln folgende Nido‐Cluster Sn. Die Packung der beiden Anionensorten kann entsprechend topologisch der Anordnung der beiden Atomsorten in den μ‐Phasen zugeordnet werden.