bluuebunny/crossref_metadata_2025 huggingface dataset:
Pleiotropic effects of Hoxa10 on the functional development of peri‐implantation endometrium
Authors: Daftary Gaurang S. , Taylor Hugh S.
Published: December 2003

Hoxa10, a homeodomain transcription factor, is dynamically expressed in adult uterine endometrium where it is necessary for embryo implantation. Endometrial Hoxa10 expression is driven by estrogen and progesterone. High levels of endometrial Hoxa10 expression coincide with high progesterone levels and development of endometrial receptivity. Although, progesterone is sufficient for endometrial differentiation and implantation, the molecular mechanisms by which progesterone mediates endometrial receptivity are not known. To determine if Hoxa10 mediates the developmental effects of progesterone in the endometrial cell compartments, we performed in vivo uterine transfection using pcDNA3.1/Hoxa10 in estrogen‐primed, ovariectomized mice and compared results to mice treated with progesterone. Additional control mice were treated with either estrogen alone or empty vector pcDNA3.1. By using ovariectomized mice, we were able to determine specific developmental effects resultant from Hoxa10 treatment and distinguish them from those mediated by the regulation of multiple endogenous genes (including Hoxa10) by ovarian progesterone. Treatment with either Hoxa10 or progesterone resulted in diminished uterine weight and increased expression of characteristic cell‐type specific differentiation markers such as epithelial calcitonin and stromal prolactin, suggesting that Hoxa10 likely mediates progesterone induced functional differentiation of endometrial epithelium and stroma. However, progesterone treatment suppressed endometrial eosinophil infiltration and degranulation compared to that seen with Hoxa10 treatment. Besides mediating progestational effects, Hoxa10 may activate distinct developmental pathways leading to endometrial differentiation. Functional differentiation in regenerative adult tissues may depend on timed expression of embryonic selector genes. Mol. Reprod. Dev. 67: 8–14, 2004. © 2004 Wiley‐Liss, Inc.
Shear stiffness estimation using intravoxel phase dispersion in magnetic resonance elastography
Authors: Glaser Kevin J. , Felmlee Joel P. , Manduca Armando , Ehman Richard L.
Published: December 2003

Dynamic MR elastography (MRE) is a phase‐contrast technique in which the periodic shear motion of an object is encoded as variations in the phase of the reconstructed images. An alternative MRE method is presented whereby waves are depicted as intensity variations in the magnitude images due to intravoxel phase dispersion (IVPD). A theoretical framework is developed to model how the IVPD magnitude data are related to the underlying shear wave motion, and how they can be used to estimate shear stiffness. The results are shown in a series of phantom experiments to demonstrate that IVPD MRE complements phase‐contrast MRE. Magn Reson Med 50:1256–1265, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized 129Xe
Authors: Månsson Sven , Wolber Jan , Driehuys Bastiaan , Wollmer Per , Golman Klaes
Published: December 2003

The ability to quantify pulmonary diffusing capacity and perfusion using dynamic hyperpolarized 129Xe NMR spectroscopy is demonstrated. A model of alveolar gas exchange was developed, which, in conjunction with 129Xe NMR, enables quantification of average alveolar wall thickness, pulmonary perfusion, capillary diffusion length, and mean transit time. The technique was employed to compare a group of naïve rats (n = 10) with a group of rats with acute inflammatory lung injury (n = 10), caused by instillation of lipopolysaccaride (LPS). The measured structural and perfusion‐related parameters were in agreement with reported values from studies using non‐NMR methods. Significant differences between the groups were found in total diffusion length (control 8.5 ± 0.5 μm, LPS 9.9 ± 0.6 μm, P < 0.001), in capillary diffusion length (control 2.9 ± 0.4 μm, LPS 3.9 ± 1.0 μm, P < 0.05), and in pulmonary hematocrit (control 0.55 ± 0.06, LPS 0.43 ± 0.08, P < 0.01), whereas no differences were observed in alveolar wall thickness, pulmonary perfusion, and mean transit time. These results demonstrate the ability of the method to distinguish two main aspects of lung function, namely, diffusing capacity and pulmonary perfusion. Magn Reson Med 50:1170–1179, 2003. © 2003 Wiley‐Liss, Inc.
Whole‐heart steady‐state free precession coronary artery magnetic resonance angiography
Authors: Weber Oliver M. , Martin Alastair J. , Higgins Charles B.
Published: December 2003

Current implementations of coronary artery magnetic resonance angiography (MRA) suffer from limited coverage of the coronary arterial system. Whole‐heart coronary MRA was implemented based on a free‐breathing steady‐state free‐precession (SSFP) technique with magnetization preparation. The technique was compared to a similar implementation of conventional, thin‐slab coronary MRA in 12 normal volunteers. Three thin‐slab volumes were prescribed: 1) a transverse slab, covering the left main (LM) artery and proximal segments of the left anterior ascending (LAD) and left circumflex (LCX) coronary arteries; 2) a double‐oblique slab covering the right coronary artery (RCA); and 3) a double‐oblique slab covering the proximal and distal segments of the LCX. The whole‐heart data set was reformatted in identical orientations. Visible vessel length, vessel sharpness, and vessel diameter were determined and compared separately for each vessel. Whole‐heart coronary MRA visualized LM/LAD (11.7 ± 3.4 cm) and LCX (6.9 ± 3.6 cm) over a significantly longer distance than the transverse volume (LM/LAD, 6.1 ± 1.1 cm, P < 0.001; LCX, 4.2 ± 1.2 cm, P < 0.05). Improvements in visible vessel length for RCA and LCX in the whole‐heart approach vs. their respective targeted volumes were not significant. It is concluded that the whole‐heart coronary MRA technique improves visible vessel length and facilitates high‐quality coronary MRA of the complete coronary artery tree in a single measurement. Magn Reson Med 50:1223–1228, 2003. © 2003 Wiley‐Liss, Inc.
Application of unconstrained optimization and sensitivity analysis to calibration of a soil constitutive model
Authors: Yang Zhaohui , Elgamal Ahmed
Published: December 2003

Large sets of soil experimental data (field and laboratory) are becoming increasingly available for calibration of soil constitutive models. A challenging task is to calibrate a potentially large number of model parameters to satisfactorily match many data sets simultaneously. This calibration effort can be facilitated by optimization techniques. The current study aims to explore systematic approaches for exercising optimization and sensitivity analysis in the area of soil constitutive modelling. Analytical, semi‐analytical and numerical optimization techniques are employed to calibrate a multi‐surface‐plasticity sand model. Calibration is based on results from a number of drained triaxial sample tests and a dynamic centrifuge liquefaction test. The analytical and semi‐analytical approaches and associated sensitivity analysis are applied to calibrate the model non‐linear shear stress–strain response. Thereafter, model parameters controlling shear–volume coupling effects (dilatancy) are calibrated using a solid–fluid fully coupled finite element program in conjunction with an advanced numerical optimization code. A related sensitivity study reveals the challenges often encountered in optimizing highly non‐linear functions. Overall, this study demonstrates applicability and limitations of optimization techniques for constitutive model calibration. Copyright © 2003 John Wiley & Sons, Ltd.
On the use of R1 and R2* for measurement of contrast agent concentration in isolated perfused rat liver
Authors: Dimicoli Jean‐Luc , Patry Jacqueline , Poupon Joël , Volk Andreas
Published: December 2003

We present experimental MRI protocols at 4.7 T for quantitative determination of the Dotarem® distribution volume in isolated perfused rat liver. The procedures involved either constant contrast agent (CA) concentration or bolus administration conditions. R1 and R2* effects of the CA in liver and perfusate were measured using gradient echo fast imaging (GEFI) experiments by varying either the excitation angle or the echo time. CA concentrations in liver and perfusate were also measured after MRI by inductively coupled plasma atomic emission spectroscopy, in order to determine in situ relaxivities in the perfusate (r1=4.2±0.1 s−1mm−1, r2*=17±2 s−1mm−1) and in the liver (r1=7.2±0.2 s−1mm−1, r2*=99±5 s−1mm−1). When CA concentrations were estimated from R1 measurements and r1, the CA distribution volume estimations in liver resulting from bolus (0.31±0.01) and stationary (0.32±0.05) experiments were not significantly different. In contrast, after a bolus, CA concentrations derived from R2* and r2* were overestimated in liver and even more in perfusate. However, with R1 and R2* being measured before CA bolus administration, zero echo time signal intensities computed from multiple TE measurements during multiple boli yielded good estimations of R1 and thus correct CA concentrations in liver and in perfusate. Under these conditions, a single multi‐echo GEFI acquisition should be sufficient to determine the concentration–time curves. Consequently, this protocol should be appropriate to rapidly estimate the distribution volume in vivo when multiple boli have to be avoided. Copyright © 2001 John Wiley & Sons, Ltd.
Indefinitely preconditioned conjugate gradient method for large sparse equality and inequality constrained quadratic problems
Authors: Durazzi C. , Ruggiero V.
Published: December 2003

This paper is concerned with the numerical solution of a symmetric indefinite system which is a generalization of the Karush–Kuhn–Tucker system. Following the recent approach of Lukšan and Vlček, we propose to solve this system by a preconditioned conjugate gradient (PCG) algorithm and we devise two indefinite preconditioners with good theoretical properties. In particular, for one of these preconditioners, the finite termination property of the PCG method is stated. The PCG method combined with a parallel version of these preconditioners is used as inner solver within an inexact Interior‐Point (IP) method for the solution of large and sparse quadratic programs. The numerical results obtained by a parallel code implementing the IP method on distributed memory multiprocessor systems enable us to confirm the effectiveness of the proposed approach for problems with special structure in the constraint matrix and in the objective function. Copyright © 2002 John Wiley & Sons, Ltd.
Multilevel governance and organizational performance: Investigating the political‐bureaucratic labyrinth
Authors: Meier Kenneth J. , O'Toole Laurence J. , Nicholson‐Crotty Sean
Published: December 2003

Research on governance has extensively explored the complex interactions of governmental, nongovernmental, and
for‐profit entities in the execution of public policy. It has consistently failed, however, to model
empirically the joint effects of political and bureaucratic actors in governance systems. To address this issue, a
theory of multilevel governance built upon the foundation of representative bureaucracy was developed and tested.
Results from an analysis of Texas school districts suggest that Latinos at all levels of the governance system,
political and managerial, influence representation at other levels. Findings also indicate that Latinos at each
level of governance have positive effects, directly and indirectly, on outcomes for Latino students. The influence
of both political and managerial actors at times extends beyond the immediately adjoining level; the effects
of such actors cascade through the governance system. The results show that a priority for systematic research
should be the identification of approaches and settings for examining the multilevel aspect of governance. ©
2004 by the Association for Public Policy Analysis and Management.
New insights into the roles of matrix metalloproteinases in colorectal cancer development and progression
Authors: Leeman Matthew F , Curran Stephanie , Murray Graeme I
Published: December 2003

This review outlines new concepts that are emerging for the functions of matrix metalloproteinases in colorectal cancer development and progression. The two main concepts that will be discussed are the role of matrix metalloproteinases in the early stages of colorectal tumour development and the functional mechanisms by which matrix metalloproteinases contribute to colorectal tumour invasion and metastasis. The matrix metalloproteinases are a group of enzymes, which have been best characterized for their ability to degrade extracellular matrix proteins and thus they have been extensively studied in tumour invasion. It is now becoming recognized that the matrix metalloproteinases have key roles in a variety of biological processes that are distinct from their well‐defined role in matrix degradation. This group of enzymes has been shown to interact with a broad range of non‐matrix proteins including growth factors and their receptors, mediators of apoptosis, and cell adhesion molecules. The elucidation of novel biological roles for the matrix metalloproteinases also challenges the current predominant concept of matrix metalloproteinases as enzymes only involved in matrix degradation. Recent studies have shown that several matrix metalloproteinases, especially matrilysin (MMP‐7), interact with the specific molecular genetic and signalling pathways involved in colorectal cancer development. In particular, matrilysin is activated at an early stage of colorectal tumourigenesis by the beta‐catenin signalling pathway. Furthermore, studies are now elucidating specific mechanisms by which individual matrix metalloproteinases, especially membrane‐type matrix metalloproteinases, interact with specific cell adhesion molecules and cytoskeletal proteins and thus contribute dynamically to colorectal tumour invasion. Copyright © 2003 John Wiley & Sons, Ltd.
CNS‐directed therapy in young children with T‐lineage acute lymphoblastic leukemia: High‐dose methotrexate versus cranial irradiation
Authors: Nathan Paul C. , Maze Ronnen , Spiegler Brenda , Greenberg Mark L. , Weitzman Sheila , Hitzler Johann K.
Published: December 2003

Background

Prophylactic use of cranial radiation therapy (CRT) in young children with acute lymphoblastic leukemia (ALL) is associated with significant long‐term morbidity. Therefore, current treatment protocols for pediatric B‐precursor ALL have abandoned prophylactic CRT in favor of intrathecal chemotherapy, combined with either high‐dose methotrexate infusions (HD‐MTX) or intensive systemic chemotherapy. In contrast, prophylactic CRT continues to be used in children with T‐lineage ALL (T‐ALL), who historically have had an inferior prognosis. We conducted a retrospective cohort study to determine the effect on survival of substituting HD‐MTX for CRT in young children with T‐ALL, a group that faces a high risk of long‐term sequelae from CRT.

Procedure

Twenty‐six children, diagnosed with T‐ALL between the ages of 1 and 5 years, were treated on the same high‐risk leukemia protocol. Central nervous system (CNS) directed therapy consisted of either CRT (1,800 cGy) or HD‐MTX (three doses of 8 g/m2), depending on the treatment era in which patients were diagnosed.

Results

Of the 24 patients who entered remission, 12 received CRT and 12 received HD‐MTX. Five‐year event‐free survival (EFS) (±SE) was 92 ± 8% in the HD‐MTX group versus 75 ± 13% in the CRT group (P = 0.23). Five‐year overall survival (OS) was 100% in the HD‐MTX group versus 75 ± 13% in the CRT group (P = 0.07). There were no CNS recurrences in the HD‐MTX group. One patient treated with CRT developed a brain tumor.

Conclusions

The use of HD‐MTX instead of CRT as CNS‐directed therapy in very young children with T‐ALL does not compromise survival, while avoiding the adverse long‐term effects of cranial irradiation. © 2003 Wiley‐Liss, Inc.
Age is an independent prognostic factor in rhabdomyosarcoma: A report from the soft tissue sarcoma committee of the children's oncology group
Authors: Joshi D. , Anderson James R. , Paidas C. , Breneman J. , Parham D.M. , Crist W.
Published: December 2003

Background

Although age <1 year at diagnosis has been associated with a worse prognosis in rhabdomyosarcoma (RMS), the relationship of age at diagnosis to clinical presentation and outcome has not been evaluated carefully. We reviewed data from recent Intergroup Rhabdomyosarcoma Study Committee (later called Group, IRSG) trials to examine this relationship in order to estimate prognosis more accurately and further refine treatment.

Procedure

We used data from IRS‐III, ‐IV Pilot, and ‐IV (1983–97, N = 2,343) to study the relationship of patient age with clinical features and prognosis in a large cohort of patients treated with contemporary therapy.

Results

We showed that, after adjusting for important prognostic factors, age was an independent risk factor for treatment failure and patients could be classified into three failure‐risk categories based on age (i.e., <1 year; 1–9 years; >10 years). Infants and adolescents were more likely to have unfavorable features, including alveolar or undifferentiated tumors and advanced Group and Stage, and also had significantly poorer failure‐free survival (FFS) than did children aged 1–9 (53 and 51% vs. 72%,P < 0.001). Although there was a difference in FFS among age categories, there was no evidence that age influences outcome within the three categories.

Conclusions

Since age relates independently to outcome after adjustment for known risk factors, it is likely that other factors, including perhaps patients' tolerance of protocol‐specified therapy, explain this relationship. © 2003 Wiley‐Liss, Inc.
Copolymers of 3,5‐dimethylphenyl acrylate and methyl methacrylate: synthesis, characterization and determination of monomer reactivity ratios
Authors: Vijayanand PS , Jone Selvamalar CS , Penlidis A , Nanjundan S
Published: December 2003

Copolymers of 3,5‐dimethylphenyl acrylate (DMPA) and methyl methacrylate (MMA) having various compositions were synthesized using free radical solution polymerization in butane‐2‐one at 70 ± 1 °C with benzoyl peroxide as initiator. The structure of the copolymer was confirmed by FTIR, 1H NMR and 13C NMR spectroscopic techniques. The polydispersity indices of the copolymers determined using gel permeation chromatography suggest that the chain termination by disproportion was predominant when the mole fraction of MMA in the feed is high and radical recombination was predominant when the mole fraction of DMPA was high in the feed. The glass transition temperature of the copolymer increases with increase in MMA content. The thermal stability of the copolymers increases with increase in DMPA content. The copolymer compositions were determined using 1H NMR analysis. The monomer reactivity ratios were determined by application of conventional linearization methods such as the Fineman–Ross (r1 = 0.3942; r2 = 2.3250), the Kelen–Tüdös (r1 = 0.3848; r2 = 2.2584), an extended Kelen–Tüdös (r1 = 0.3608; r2 = 2.3384) and a non‐linear error‐in‐variables model method using a computer program, RREVM (r1 = 0.3879; r2 = 2.2642). These values suggest that MMA is more reactive than DMPA and the copolymer will be richer in MMA units. Copyright © 2003 Society of Chemical Industry
Phase transformations of some poly(vinyl alcohol)–NiCl2 composites
Authors: El‐Shahawy Magda A
Published: December 2003

Samples of poly(vinyl alcohol)–NiCl2 composites containing up to 30 wt% NiCl2 were prepared by casting in order to study phase transformation–structural change relationships of these samples before and after heat treatment. Differential thermal analysis (DTA) thermograms were recorded at 10, 15, 20 and 30 °C min−1. For untreated samples four endotherms were assigned as: rotation of hydroxyl groups in the glassy state, glass transition, structural transition in the rubber‐like state, and melting transition. Ultrasonic attenuation measurements were carried out to confirm these transitions in the glassy and rubber‐like states. In the glassy state, the effect of NiCl2 addition is explained in terms of chain stiffness due to the creation of local crosslinked regions in amorphous parts of the polymer. Average values of activation energies for glass transition were calculated using both methods of Kissinger and Ozawa. However, addition of NiCl2 had an opposite effect on the heating rate independent crystallization melting temperature (Tm), relative to that on Tg. The DTA thermograms of heat‐treated samples indicated that square planar NiCl2 molecules were embedded in the polymer matrix with no local crosslinking role due to the formation of conjugated polyenes along the polymer chains by thermal treatment. Copyright © 2003 Society of Chemical Industry
Cross‐linking of polybutadiene: correlation between solid‐state 1H NMR spectroscopy, thermoporosimetry, densimetry and crystallinity measurements
Authors: Pilichowski Jean‐Francois , Liptaj Tibor , Morel Myriam , Terriac Emmanuel , Baba Mohamed
Published: December 2003

T2 proton NMR relaxation times were used to follow the changes in the macromolecular chain mobility of a chemically (by dicumyl peroxide) cross‐linked polybutadiene matrix. The same phenomenon was also studied by an investigation of the ability of the polymer to crystallize using DSC measurements. The solubility of the elastomer depends on the size of its macromolecular chains. Cross‐linking, leading to an increase in the size of macromolecules, provokes an insolubility of the elastomer. By densimetry measurements, it was possible to follow the changes in the solubility of the polymer up to its gel‐point. Beyond the gel‐point, the swelling solvent, cyclohexane, was used as a textural probe. Using the shift of its solid‐solid thermal transition points, it was possible to calculate the distribution of the distances between the cross‐links as a function of the curing times by thermoporosimetry analysis. Copyright © 2003 Society of Chemical Industry
Phase transformation to β‐poly(vinylidene fluoride) by milling
Authors: Esterly Daniel M. , Love Brian J.
Published: December 2003

Cryogenic mechanical milling successfully converted α‐phase poly(vinylidene fluoride) (PVDF) powder into β‐phase PVDF, as measured by wide‐angle X‐ray diffraction. The presence of β‐phase PVDF became more pronounced with increased milling times over the limited time range evaluated. This was the first recorded instance of β‐phase powders forming from the α phase through milling. These β‐phase powders maintained their crystal structure during compression molding at 70 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 91–97, 2004
Curing of linear and crosslinked epoxy systems: A fluorescence study with dansyl derivatives
Authors: Mikeš František , González‐Benito Javier , Llidó Juan Baselga
Published: December 2003

The curing of diglycidyl ether of bisphenol A (DGEBA) with N,N′‐dimethylethylenediamine (N,N′‐DMEDA) or ethylenediamine (EDA) was monitored by fluorescence spectroscopy and Fourier transform infrared (in the near‐infrared region). 5‐Dimethylamino‐naphthalene‐1‐sulfonamide (DNS) derivatives were used as probes (fluorophores added to the reaction mixture) and labels (fluorophores attached by covalent bonds to diglycidyl reactants). The term containing the ratio of the reaction rate constants for the addition of the secondary and primary amine hydrogens to the epoxide was included in the reduced reaction rate term for the autocatalyzed and catalyzed epoxide curing reactions. The changes in the integrated fluorescence intensities of the labels during the epoxy group conversion indicated, in some cases, the most important changes in the chemical transformations of the reaction mixture: the epoxy group conversion, during which a rapid increase in the tertiary amino group concentration was first observed; the gel point (for EDA); and the entry of the system into the glassy state (for N,N′‐DMEDA and EDA). The fluorescence probes monitored neither the gel point nor the threshold of the glassy state. For the DGEBA–N,N′‐DMEDA system, a wavy dependence of the integrated fluorescence intensities of the DNS labels on the epoxy group conversion might reflect the molar concentrations of polymer homologues (referred to the initial number of moles in the system) in the reaction mixtures of the diepoxide and secondary diamine. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 64–78, 2004
The interaction between poly(N‐isopropylacrylamide) and salts in aqueous media: The “salting‐out” phenomenon as studied by attenuated total reflection/fourier transform infrared spectroscopy
Authors: Paz Yaron , Kesselman Ellina , Fahoum Lulu , Portnaya Irina , Ramon Ory
Published: December 2003

The effect of two strong salting‐out salts (Na2SO4 and K2SO4) on the temperature‐induced phase‐separation process in aqueous solutions of poly(N‐isopropylacrylamide) (PNIPA) was examined by attenuated total reflectance/Fourier transform infrared spectroscopy, differential scanning calorimetry, and viscosity measurements. On the basis of these measurements, a detailed scenario of the phase‐separation process was deduced. The phase‐separation scenario of solutions containing PNIPA and water was altered in the presence of sulfate ions. Here, the sulfate ions induced partial intrachain collapse, manifested by a relatively compact structure well below the lower critical solution temperature. This led to a more gradual, smooth phase transition, with temperature‐resolved intrachain collapse and interchain aggregation and a lesser extent of hysteresis. Although at the macrolevel one may not be able to differentiate among various scenarios altering the solvent into a poor solvent, the aforementioned microlevel measurements provided a way to expose the difference between raising the temperature and adding cosolutes. Follow‐up studies on the effect of salting‐in salts will be presented. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 33–46, 2004
Biopolymer mimicry with polymeric wormlike micelles: Molecular weight scaled flexibility, locked‐in curvature, and coexisting microphases
Authors: Dalhaimer Paul , Bermudez Harry , Discher Dennis E.
Published: December 2003

Giant and stable wormlike micelles formed in water from a series of poly(ethylene oxide) (PEO)‐based diblock copolymer amphiphiles mimicked the flexibility of various cytoskeletal filaments. The worm diameter (d) was found by cryo‐transmission electron microscopy to scale with the length of the hydrophobic chain (Nh) of the copolymer as d ∼ Nh0.61. By fluorescence video imaging of worm dynamics, we also showed that the persistence length (lP) of wormlike micelles scaled as lP ∼ d2.8, consistent with a fluid aggregate (∼d3) rather than a solid rod (∼d4). By polymerizing the unsaturated bonds of assembled copolymers, fluid worms were converted to solid‐core worms, extending the bending rigidity from that of intermediate filament biopolymers to actin filaments and, in principle, microtubules. Through partial crosslinking, polymerized worms further locked in spontaneous curvature at a novel fluid‐to‐solid percolation point. The dynamics of distinct, branched conformations were also imaged for recently discovered Y‐junctioned wormlike micelles composed of diblocks of high molecular weight (>10–15 kg/mol). Finally, block copolymers of hydrophilic weight fraction close to the transition between a vesicle‐ and worm‐former assembled into both structures, allowing encapsulation of wormlike micelles in giant vesicles reminiscent of cytoskeletal filaments enclosed within cells. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 168–176, 2004
The potential use of continuous‐flow isotope‐ratio mass spectrometry as a tool in forensic soil analysis: a preliminary report
Authors: Croft Debra J. , Pye Kenneth
Published: December 2003

The use of continuous‐flow isotope‐ratio mass spectrometry (CF‐IRMS) as a tool in soil analysis has been assessed as part of a larger study using a number of geological techniques applied in a forensic context. Carbon and nitrogen isotopic ratios, δ13C and δ15N, have been analysed to investigate situations which have arisen from crime casework. Three questions have been addressed: the role of spatial variation found over the short‐scale (less than 20 m), temporal variation over a period of almost 2 years, and the variation found between source soils and soil transferred to footwear soles during a simple one‐stage transfer process. Results are presented for the three experiments. The use of carbon and nitrogen isotopes has been shown to be useful in discriminating between soil types and sample locations, even when sampling occurs at a different time (as might be the case with a crime scene). In cases of primary transfer (from a source soil by a one‐stage transfer to another surface, in this case, shoes and boots), the combination of carbon and nitrogen isotope ratios is a valuable tool in discriminating between sites and in showing the relationship of the transferred samples to the relevant source soils. Used in combination with other analytical techniques, isotopic analysis may prove to be a useful tool in a forensic context. Copyright © 2003 John Wiley & Sons, Ltd.
Use of compound‐specific δ13C and δD stable isotope measurements as an aid in the source apportionment of polyaromatic hydrocarbons
Authors: Sun Chenggong , Cooper Mick , Snape Colin E.
Published: December 2003

The potential of using compound‐specific stable carbon isotopic analysis for the source apportionment of environmental polycyclic aromatic hydrocarbons (PAHs) has already been demonstrated by the authors, and other researchers. PAHs arising from wood burning and vehicle emissions have been shown to exhibit different isotopic signatures, and the isotopic compositions of n‐alkanes and PAHs produced from combustion of C3 and C4 plant species have been reported. 13C/12C isotopic ratios for PAHs derived from coal and wood pyrolysis and from diesel particulates have been noted to vary over a range by ca. 8‰, which may provide a basis for source apportionment. In order to further improve the ability of stable isotope measurements to source apportion environmental PAHs, hydrogen stable isotopes (δD) of PAHs from a number of processes have been measured. The wide range of δD values, in conjunction with the δ13C values obtained, provide a much greater degree of differentiation between petrol and jet fuel derived PAHs, and between PAHs from different coal conversion processes, than the δ13C values alone. Copyright © 2003 John Wiley & Sons, Ltd.
Performance evaluation of a reservation TDMA protocol for voice/data transmissions in a LEO satellite communication system
Authors: Fantacci Romano , Nannicini Saverio , Pecorella Tommaso
Published: December 2003

In this paper, the capability is investigated of a reservation TDMA‐based protocol to support constant bit rate and best‐effort traffics in Low Earth Orbit (LEO) satellite communication systems under typical propagation conditions. Differently from several previous papers on the same subject, we focus here on a communication channel affected by multipath fading and characterized by a high round trip delay. In our protocol, a higher priority is given to constant bit rate terminals with respect to best‐effort data terminals. The performance for constant bit rate and best‐effort terminals was derived by means of a suitable analytical approach and computer simulations. The results shown herein permits to evaluate the influence of the channel propagation conditions on the system performance. Moreover, they highlight that the reservation TDMA protocol exhibits a good behaviour for the communication channel under consideration and in comparison with a recent protocol based on the classical PRMA scheme. Copyright © 2003 John Wiley & Sons, Ltd.
Sensitivity studies for quantitative assays: use of censored data analysis
Authors: Weusten Jos J. A. M. , Wouters Pieter A. W. M. , van Zuijlen Martien C. A.
Published: December 2003

Probit regression analysis is frequently used to study the relation between the concentration of an analyte in a sample and the probability that the assay used yields a positive test result. For these analyses only the qualitative classification ‘positive’ or ‘negative’ is used, whereas, particularly in the case where the assay is quantitative in nature, the results contain more information. In the current paper, we propose an alternative method, in which the negative test results are treated as being (left) censored. As such, more efficient use is made of the information in the data. The procedures are illustrated using two generations of NucliSens assays (BioMérieux), which are designed to quantify the viral load of HIV‐1 in blood samples. Computer simulations are used to illustrate some properties of the estimated parameters. Copyright © 2003 John Wiley & Sons, Ltd.
Bayesian approaches to multiple sources of evidence and uncertainty in complex cost‐effectiveness modelling
Authors: Spiegelhalter David J , Best Nicola G
Published: December 2003

Increasingly complex models are being used to evaluate the cost‐effectiveness of medical interventions. We describe the multiple sources of uncertainty that are relevant to such models, and their relation to either probabilistic or deterministic sensitivity analysis. A Bayesian approach appears natural in this context. We explore how sensitivity analysis to patient heterogeneity and parameter uncertainty can be simultaneously investigated, and illustrate the necessary computation when expected costs and benefits can be calculated in closed form, such as in discrete‐time discrete‐state Markov models. Information about parameters can either be expressed as a prior distribution, or derived as a posterior distribution given a generalized synthesis of available data in which multiple sources of evidence can be differentially weighted according to their assumed quality. The resulting joint posterior distributions on costs and benefits can then provide inferences on incremental cost‐effectiveness, best presented as posterior distributions over net‐benefit and cost‐effectiveness acceptability curves. These ideas are illustrated with a detailed running example concerning the cost‐effectiveness of hip prostheses in different age–sex subgroups. All computations are carried out using freely available software for conducting Markov chain Monte Carlo analysis. Copyright 2003 John Wiley & Sons, Ltd.
Simulations for very early lifecycle quality evaluations
Authors: Chiang Eliza , Menzies Tim
Published: December 2003

Chunget al.have proposed a graphical model that captures the interdependencies between design alternatives in terms of synergy and trade‐offs. This model can assist in identifying quality/risk trade‐offs early in the lifecycle of software development, such as architectural design and testing process choices. The Chunget al.method is an analysis framework only: their technique does not include an execution or analysis module. This paper presents a simulation tool developed to analyze such a model, and techniques to facilitate decision making by reducing the space of options worth considering. Our techniques combine Monte Carlo simulations to generate options with a machine learner to determine which option yields the most/least favorable outcome. Experiments based on the above methodology were performed on two case studies, and the results showed that treatment learning successfully pinpointed the key attributes among uncertainties in our test domains. Copyright © 2003 John Wiley & Sons, Ltd.
A system dynamics metamodel for software process modeling
Authors: De Oliveira Barros Márcio , Werner Cláudia Maria Lima , Travassos Guilherme Horta
Published: December 2003

In this paper we describe a metamodel to the system dynamics language that allows the development of software process models based on high‐level constructors instead of mathematical equations. These constructors represent software process domain concepts such as developers, activities, resources and artifacts. A domain model allows the translation of these concepts to traditional stock‐and‐flow diagrams, which can be simulated to evaluate the behavior of software process models. The proposed approach helps inexperienced modelers to build process models by reducing the semantic gap between system dynamics and the software process domain. Thus, resulting models are more readable, easier to understand and maintain. We provide an example of a process model built with the proposed approach presenting its translation and simulation processes. Copyright © 2003 John Wiley & Sons, Ltd.
IMMoS: a methodology for integrated measurement, modelling and simulation
Authors: Pfahl Dietmar , Ruhe Günther
Published: December 2003

One reason for the relatively small number of real‐world applications of simulation in software engineering is the existing lack of guidance in creating and formulating the related models and in the isolated usage of associated techniques. In order to support both strategic and project management in software organizations, a methodology for integrated measurement, modelling and simulation (IMMoS) was developed and validated. The hybrid approach integrates the individual strengths of its inherent methodological elements and concepts. The core element of IMMoS is the simulation modelling method system dynamics (SD), which integrates quantitative dynamic models with quantitative and qualitative static models in a natural way. The novelty of IMMoS is twofold. First, it enhances existing guidance for SD modelling by adding a component that enforces goal‐orientation, and by providing a refined process model with detailed description of activities, entry/exit criteria, input/output products, and roles involved. Secondly, it describes how to combine SD modelling with goal‐oriented measurement and descriptive process modelling, thus improving efficiency and smoothly closing the gap to established methods in empirical software engineering. IMMoS has been initially evaluated. The effectiveness and efficiency of IMMoS is supported with empirical evidence from two industrial case studies and one controlled experiment. Copyright © 2003 John Wiley & Sons, Ltd.
Application of multimedia techniques in the physical rehabilitation of Parkinson's patients
Authors: Camurri Antonio , Mazzarino Barbara , Volpe Gualtiero , Morasso Pietro , Priano Federica , Re Cristina
Published: December 2003

This paper presents and discusses some experiments having the purpose of planning, developing and validating aesthetically resonant environments for different types of sensorimotor impairments which affect Parkinson's patients. From a technical point of view the aim is to develop a computational open architecture in which it is possible to integrate modules for gesture analysis and recognition and for interactive construction of therapeutic exercises based on multimedia stimulation in real time. The clinical objective is to experiment with a device of sensorimotor stimulation that supports akinesia compensation by controlling movement rhythmic structures in subjects with Parkinson's disease. The EyesWeb open architecture has been used to analyse patients' motion and to produce visual feedback during therapy sessions in real time. A pilot study has been conducted on two Parkinson's disease patients in the framework of the EU IST project CARE‐HERE. Copyright © 2003 John Wiley & Sons, Ltd.
A learning strategy for paging in mobile environments
Authors: Koukoutsidis I. Z. , Demestichas P. P. , Theologou M. E.
Published: December 2003

The essence of designing a good paging strategy is to incorporate the user mobility characteristics in a predictive mechanism that reduces the average paging cost with as little computational effort as possible. In this scope, we introduce a novel paging scheme based on the concept of reinforcement learning. Learning endows the paging mechanism with the predictive power necessary to determine a mobile terminal's position, without having to extract a location probability distribution for each specific user. The proposed algorithm is compared against a heuristic randomized learning strategy akin to reinforcement learning, that we invented for this purpose, and performs better than the case where no learning is used at all. It is shown that if the user normally moves only among a fraction of cells in the location area, significant savings can be achieved over the randomized strategy, without excessive time to train the network. Copyright © 2003 John Wiley & Sons, Ltd.
A full rate space‐time turbo codes and its near‐optimum decoding algorithms
Authors: Li Yong‐Hui , Li Dao‐Ben
Published: December 2003

A novel full rate space‐time turbo codes are presented in this paper. Simulation results and theoretical analysis exhibit its excellent performance. At the encoder, information bits are encoded using a concatenated space‐time turbo coder, and then coded symbols are modulated and assembled by a pre‐defined function rather than punctured as in other schemes. It can achieve lower code rate (because it doesn't puncture the coded signals), get more coding gains and take advantage of both space and time diversity. Since its decoding needs to calculate two extrinsic probabilities simultaneously, traditional Log‐Map decoding algorithm fails to be used directly. An extended 2‐dimensional (2‐D) Log‐Map (maximum a posterior probability) decoding algorithm and another one based on Bayesian Network are developed to decode the proposed scheme. Under the same conditions, the proposed scheme will bring about 12 dB gains at BER 1.0e−5 and about 12–14 dB gains at FER 1.0e−3 over some other known schemes at quasi‐static fading channels, and above 10 dB at BER 1.0e−5 and FER 1.0e−3 over time‐varying fading channels. Copyright © 2003 John Wiley & Sons, Ltd.
Uplink packet scheduling in the presence of interference cancellation in multi‐rate wireless CDMA networks
Authors: Aïssa Sonia , Maaref Amine , Mermelstein Paul
Published: December 2003

We consider packet scheduling and rate assignment on the uplink of a packet data wireless CDMA network in the presence of imperfect interference cancellation (IC) and limited user transmission rates, and subject to in‐cell and out‐of‐cell resource limitations. The objective is to propose and implement a system level position‐based flow control algorithm that accounts for a limited IC capability provided by power control for multi‐user detection. The proposed algorithm assigns packets to be transmitted to separate queues, one for each spatial zone within which packets generate roughly the same in‐cell interference and impose equal interference on a neighboring base station. Given the cell partitioning into zones, the algorithm dynamically adapts to the resource constraints and efficiently uses IC to provide for fairness in serving the various queues without giving up the objective of maximizing data throughput. Throughput and fairness are the two conflicting objectives to be optimized. We show that the joint use of IC and location‐based scheduling is able to achieve complete fairness with negligible loss in throughput even under stringent resource limitations. The IC technique implemented is based on the interference subspace rejection (ISR) technique. We investigate both successive and group cancellation modes of ISR. Through the zone‐based grouping of users, the flow control algorithm provides a high flexibility in taking advantage of IC and is general enough to adapt to situations with constraints on the transmission rates. Results provided show how group‐based scheduling with group‐cancellation can provide for high fairness even under stringent out‐of‐cell resource limitations. Copyright © 2003 John Wiley & Sons, Ltd.
A QoS‐based charging and resource allocation framework for next generation wireless networks
Authors: Ibrahim Walid , Chinneck John W. , Periyalwar Shalini
Published: December 2003

Wireless networks are evolving to include Internet access to interactive multimedia and video conferencing as well as traditional services such as voice, email and web access. These new applications can demand large amounts of network resources, such as bandwidth, to achieve the highest levels of quality (e.g. picture quality). In conjunction with this trend, charging and resource allocation systems must evolve to explicitly consider the trade‐off between resource consumption and the Quality of Service (QoS) provided. This paper proposes a novel QoS‐based charging and resource allocation framework. The framework allocates resources to customers based on their QoS perceptions and requirements, thereby charging fairly while improving resource allocation efficiency. It also allows the network operators to pursue a wide variety of policy options, including maximizing revenue or using auction or utility‐based pricing. Copyright © 2003 John Wiley & Sons, Ltd.
Radio resource management techniques for UE‐MAC in 3GPP W‐CDMA systems
Authors: Cheng Sheng‐Tzong , Lin Jian‐Liang
Published: December 2003

The selection of transport format combination (TFC) is a fast part of the radio resource management because the bit rate can be changed very fast without any need for network layer signaling. However, the data transmitted by the TFC with higher data rate will suffer higher bit error rate (BER) because of the interference between the data that transmitted by the same TFC. This paper investigates this problem and proposes a BER filtering strategy to filter out some infeasible TFCs in a given transport format combination set (TFCS). Based on the BER filtering strategy, three kinds of the TFC selection methods are developed to dynamically assign transport blocks to logical channels on‐demand so as to utilize the finite bandwidth. According to a performance index that takes the priority into consideration, the feasibility and the effectiveness of the proposed TFC selection algorithms have also been demonstrated from the simulation results. Copyright © 2003 John Wiley & Sons, Ltd.
Viscous and Aeroelastic Effects on Wind Turbine Blades. The VISCEL Project. Part II: Aeroelastic Stability Investigations
Authors: Chaviaropoulos P. K. , Soerensen N. N. , Hansen M. O. L. , Nikolaou I. G. , Aggelis K. A. , Johansen J. , Gaunaa Mac , Hambraus T. , von Geyr Heiko Frhr. , Hirsch Ch. , Shun Kang , Voutsinas S. G. , Tzabiras G. , Perivolaris Y. , Dyrmose S. Z.
Published: December 2003

The recent introduction of ever larger wind turbines poses new challenges with regard to understanding the mechanisms of unsteady flow–structure interaction. An important aspect of the problem is the aeroelastic stability of the wind turbine blades, especially in the case of combined flap/lead–lag vibrations in the stall regime. Given the limited experimental information available in this field, the use of CFD techniques and state‐of‐the‐art viscous flow solvers provides an invaluable alternative towards the identification of the underlying physics and the development and validation of sound engineering‐type aeroelastic models. Navier–Stokes‐based aeroelastic stability analysis of individual blade sections subjected to combined pitch/flap or flap/lead–lag motion has been attempted by the present consortium in the framework of the concluded VISCEL JOR3‐CT98‐0208 Joule III project. Copyright © 2003 John Wiley & Sons, Ltd.