bluuebunny/crossref_metadata_2025 huggingface dataset:
SSFP‐based MR thermometry
Authors: Paliwal Vaishali , El‐Sharkawy AbdEl‐Monem , Du Xiangying , Yang Xiaoming , Atalar Ergin
Published: September 2004

Of the various techniques employed to quantify temperature changes by MR, proton resonance frequency (PRF) shift‐based phase‐difference imaging (PDI) is the most accurate and widely used. However, PDI is associated with various artifacts. Motivated by these limitations, we developed a new method to monitor temperature changes by MRI using the balanced steady‐state free precession (balanced‐SSFP) pulse sequence. Magnitude images obtained with the SSFP pulse sequence were used to find the PRF shift, which is proportional to temperature change. Spatiotemporal temperature maps were successfully reconstructed with this technique in gel phantom experiments and a rabbit model. The results show that the balanced‐SSFP‐based method is a promising new technique for monitoring temperature. Magn Reson Med 52:704–708, 2004. © 2004 Wiley‐Liss, Inc.
Displacement‐encoded cardiac MRI using cosine and sine modulation to eliminate (CANSEL) artifact‐generating echoes
Authors: Epstein Frederick H. , Gilson Wesley D.
Published: September 2004

Displacement‐encoded imaging with stimulated echoes (DENSE) and harmonic phase imaging (HARP) employ 1‐1 spatial modulation of magnetization to cosine modulate the longitudinal magnetization as a function of position at end diastole. Later in the cardiac cycle they sample the cosine‐modulated signal and compute myocardial strain from the signal phase. The sampled signal generally includes three distinct echoes: 1) a displacement‐encoded stimulated echo, 2) the complex conjugate of the displacement‐encoded echo, and 3) an echo arising from T1 relaxation. If the T1‐relaxation and complex conjugate echoes are suppressed, then a phase image representing just the displacement‐encoded echo can be reconstructed. In the present study, the use of cosine and sine modulation to eliminate (CANSEL) the T1‐relaxation and complex conjugate echoes was investigated. With the use of CANSEL, it was demonstrated that DENSE accurately measures through‐plane as well as in‐plane components of tissue motion. Also, DENSE with CANSEL artifact suppression can provide increased signal‐to‐noise ratio (SNR) secondary to reduced intravoxel dephasing by using relatively low displacement‐encoding frequencies. For applications that employ DENSE imaging with multiple acquisitions, the CANSEL technique can suppress artifact‐generating echoes without placing constraints on the displacement‐encoding frequency and direction. Magn Reson Med 52:774–781, 2004. © 2004 Wiley‐Liss, Inc.
Optimal design of k‐space trajectories using a multi‐objective genetic algorithm
Authors: Dale Brian M. , Lewin Jonathan S. , Duerk Jeffrey L.
Published: September 2004

Spiral, radial, and other nonrectilinear k‐space trajectories are an area of active research in MRI due largely to their typically rapid acquisition times and benign artifact patterns. Trajectory design has commonly proceeded from a description of a simple shape to an investigation of its properties, because there is no general theory for the derivation of new trajectories with specific properties. Here such a generalized methodology is described. Specifically, a multi‐objective genetic algorithm (GA) is used to design trajectories with beneficial flow and off‐resonance properties. The algorithm converges to a well‐defined optimal set with standard spiral trajectories on the rapid but low‐quality end, and a new class of trajectories on the slower but high‐quality end. The new trajectories all begin with nonzero gradient amplitude at the k‐space origin, and curve gently outward relative to standard spirals. Improvements predicted in simulated imaging experiments were found to correlate well with improvements in actual experimental measures of image quality. The impact of deviations from the desired k‐space trajectory is described, as is the impact of using different phantoms. Magn Reson Med 52:831–841, 2004. © 2004 Wiley‐Liss, Inc.
Improving the spatial specificity of canonical correlation analysis in fMRI
Authors: Nandy Rajesh , Cordes Dietmar
Published: September 2004

The contrast‐to‐noise ratio (CNR) is often very low in fMRI data, and standard univariate methods suffer from a loss of sensitivity in the context of noise. The increased power of a multivariate statistical analysis method known as canonical correlation analysis (CCA) in fMRI studies with low CNR was established previously. However, CCA in its conventional form has weak spatial specificity. In this work we propose a new assignment scheme to rectify this problem. It is shown that the new method has improved spatial specificity as well as sensitivity compared to conventional CCA for detecting activation patterns in fMRI. Magn Reson Med 52:947–952, 2004. © 2004 Wiley‐Liss, Inc.
Dynamic MRI with projection reconstruction and KWIC processing for simultaneous high spatial and temporal resolution
Authors: Song Hee Kwon , Dougherty Lawrence
Published: September 2004

A method for dynamic imaging in MRI is presented that enables the acquisition of a series of images with both high temporal and high spatial resolution. The technique, which is based on the projection reconstruction (PR) imaging scheme, utilizes distinct data acquisition and reconstruction strategies to achieve this simultaneous capability. First, during acquisition, data are collected in multiple undersampled passes, with the view angles interleaved in such a way that those of subsequent passes bisect the views of earlier ones. During reconstruction, these views are weighted according to a previously described k‐space weighted image contrast (KWIC) technique that enables the manipulation of image contrast by selective filtering. Unlike conventional undersampled PR methods, the proposed dynamic KWIC technique does not suffer from low image SNR or image degradation due to streaking artifacts. The effectiveness of dynamic KWIC is demonstrated in both simulations and in vivo, high‐resolution, contrast‐enhanced imaging of breast lesions. Magn Reson Med 52:815–824, 2004. © 2004 Wiley‐Liss, Inc.
Observation of nonlinear shear wave propagation using magnetic resonance elastography
Authors: Sack Ingolf , Mcgowan Christopher K. , Samani Abbas , Luginbuhl Chris , Oakden Wendy , Plewes Donald B.
Published: September 2004

MR elastography (MRE) is an MRI modality that is increasingly being used to image tissue elasticity throughout the body. One MRE technique that has received a great deal of attention is based on visualizing shear waves, which reveal stiffness by virtue of their local wavelength. However, the shape of propagating shear waves can also provide valuable information about the nonlinear stress–strain behavior of tissue. Here an experiment is proposed that allows the observation of nonlinear wave propagation based on spatial‐temporal phase contrast images. A theoretical description of the wave propagation was developed that reflects typical MRE excitation, which involves excitation modes both parallel and perpendicular toB0. Based on this model, it is shown that both odd and even higher harmonics are produced with their amplitudes dependent on the details of the actuator, imaging geometry, and the nonlinear tissue properties. With appropriate motion encoding, harmonic vibrations arising from nonlinear tissue response can be detected. The effect is demonstrated on an agarose gel phantom using a sinusoidal shear vibration of 150 Hz, and clearly shows the presence of harmonics at 600 and 750 Hz. Using an estimate of the strain energy of the phantom, we were able to determine the nonlinear tissue properties. Magn Reson Med 52:842–850, 2004. © 2004 Wiley‐Liss, Inc.
Single‐acquisition sequence for the measurement of oxygen partial pressure by hyperpolarized gas MRI
Authors: Fischer M.C. , Spector Z.Z. , Ishii M. , Yu J. , Emami K. , Itkin M. , Rizi R.
Published: September 2004

Magnetic resonance imaging (MRI) with hyperpolarized 3‐helium gas (HP 3He) offers the possibility of studying functional lung parameters such as the alveolar oxygen concentration and oxygen depletion rate. Until now, a double‐acquisition technique has been utilized to extract these parameters. A complicated single‐acquisition technique was previously developed to avoid the necessity of performing two identical breathing maneuvers. The results obtained with this technique were significantly less accurate than the results obtained with the double‐acquisition method. In this work, a novel, easily implemented single‐acquisition sequence is presented that provides results comparable to those obtained with the established double‐acquisition method. This method is demonstrated in a phantom and a pig model on a 1.5 T scanner using a 2D fast low‐angle shot (FLASH) gradient‐echo sequence. Numerical simulations of the time evolution of the oxygen concentration were performed. Simulation results are presented to support the experimental data. Various parameter regimes were experimentally and numerically investigated. Magn Reson Med 52:766–773, 2004. © 2004 Wiley‐Liss, Inc.
NMR analysis of neutrophil activation in sputum samples from patients with cystic fibrosis
Authors: Saude Erik J. , Lacy Paige , Musat‐Marcu Sorin , Mayes Damon C. , Bagu John , Man S.F. Paul , Sykes Brian D. , Moqbel Redwan
Published: September 2004

Disorders of the respiratory system, such as cystic fibrosis (CF), involve the infiltration and activation of airway inflammatory cells, including neutrophils. This leads to the secretion of peroxidases, which react further with substrates in solution to produce oxidative metabolites, such as 3‐chlorotyrosine. Elevated levels of modified tyrosine residues in the airways of patients with CF may be detectable by nuclear magnetic resonance (NMR) in correlation with inflammatory cell influx. In this study, high‐resolution (500 MHz) 1H NMR was used to analyze the production of modified tyrosine residues resulting from in vitro stimulation of peripheral blood eosinophils and neutrophils, as well as in sputum samples from control subjects and patients with CF. Following in vitro stimulation, purified peripheral blood neutrophils generated 3‐chlorotyrosine, while eosinophils produced predominantly 3‐bromotyrosine and 3,5‐dibromotyrosine. Chlorinated and brominated tyrosine residues were detected in sputum samples from patients with CF (N = 7), but were not detected in the control group (N = 9). Neutrophil counts in CF sputum correlated strongly with the presence of 3‐chlorotyrosine (r2 = 0.869). Our findings indicate that neutrophil and eosinophil activation in CF is detectable by NMR. NMR may be a useful tool for the detection of biological markers of inflammatory processes in patient airways. Magn Reson Med 52:807–814, 2004. © 2004 Wiley‐Liss, Inc.
Spatial chaos of 3‐D elastica with the Kirchhoff gyrostat analogy using Melnikov integrals
Authors: Leung A. Y. T. , Kuang J. L.
Published: September 2004

The Kirchhoff kinetic analogy, from which the similarity between the governing equations for the static spatial equilibrium of a 3‐D elastica and those for the temporal dynamics of a rigid body is constituted, is revisited. The Melnikov integrals for detecting chaos cannot be easily formed for an elastica. We shall modify the previous procedure of using the Melnikov integrals for detecting temporal chaos for a gyrostat to solve the spatial chaos problem of an elastica. One way to find the disturbed Hamiltonian equations of the equilibrium equations of the elastica are by means of Deprit's variables. Using the Melnikov integrals, the spatially chaotic deformation patterns can be resulted from the homoclinic transversal intersections of the stable and unstable manifolds at a saddle point in the Poincare map when the elastica is disturbed by constant stress‐resultants. The Melnikov integrals are integrated for detecting homoclinic intersections. The equations governing the evolution of the stress‐couples and the stress‐resultants are numerically integrated using the fourth Runge–Kutta algorithms to crosscheck the analytical results. The phase portraits of the Poincare sections are created on a number of hyper‐planes to demonstrate the chaotic patterns of the stationary spatial deformations along the centreline of the elastica under weightless conditions. The bounded, non‐periodic solutions to the equilibrium of the elastica clearly show the existence of spatially chaotic deformation patterns. The findings in this paper are useful in many structures in which the elastica are important. Examples are the mathematical modelling of the DNA super‐coiling, submarine cables and the design of the tethered satellites. Copyright © 2004 John Wiley & Sons, Ltd.
Generating signals of drug‐adverse effects from prescription databases and application to the risk of arrhythmia associated with antibacterials
Authors: Corrao Giovanni , Botteri Edoardo , Bagnardi Vincenzo , Zambon Antonella , Carobbio Alessandra , Falcone Chiara , Leoni Olivia
Published: September 2004

Background

Although it is well known that a variety of antibacterials may incidentally cause malignant arrhythmia, the list of drugs causing arrhythmia and the impact of these adverse effects are still uncertain. We investigated on this topic by using a large prescription database with different observational designs.

Methods

Prescription data on all incident users of several antibacterial and antiarrhythmic drugs over the period July 1997 through December 1999 were retrieved from the Drug Prescription Database (DPD) of the Italian Province of Varese. The association between the use of antibacterial and antiarrhythmic drugs was investigated by applying prescription sequence symmetry, cohort and nested case‐control designs.

Results

Lower proarrhythmic effects were on an average obtained from prescription sequence symmetry approach with respect to both cohort and nested case‐control. Evidence of association between exposure to drugs (erythromycin and ciprofloxacin) and the risk of arrhythmia was consistently found by the three approaches. No other signals were generated from the prescription sequence symmetry analysis. Two drugs (clarithromycin and levofloxacin) showed patterns compatible with an arrhythmic effect according to both cohort and nested case‐control designs.

Conclusions

Prescription databases are useful tools to explore drug safety through both conventional and emerging observational designs. In spite of its appealing features, prescription sequence symmetry design shows lower sensitivity with respect to conventional designs. Evidence about the association between the use of certain macrolides and fluoroquinolones and the onset of arrhythmia is confirmed by this study. Copyright © 2004 John Wiley & Sons, Ltd.
Reaction‐induced phase separation in epoxy/polysulfone/poly(ether imide) systems. I. Phase diagrams
Authors: Giannotti M. I. , Foresti M. L. , Mondragon I. , Galante M. J. , Oyanguren P. A.
Published: September 2004

Epoxy–aromatic diamine formulations are simultaneously modified with two immiscible thermoplastics (TPs), poly(ether imide) (PEI) and polysulfone (PSF). The epoxy monomer is based on diglycidyl ether of bisphenol A and the aromatic diamines (ADs) are either 4,4′‐diaminodiphenylsulfone or 4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline). The influence of the TPs on the epoxy–amine kinetics is investigated. It is found that PSF can act as a catalyst. The presence of the TP provokes an increase of the gel times. Cloud‐point curves (temperature vs. composition) are shown for epoxy/PSF/PEI and epoxy/PSF/PEI/AD initial mixtures. Phase separation conversions are reported for the reactive mixtures with various TP contents and PSF/PEI proportions. On the basis of phase separation and gelation curves, conversion–composition phase diagrams at constant temperature are generated for both systems. These diagrams can be used to design particular cure cycles to generate different morphologies during the phase separation process, which is discussed in the second part of this series. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3953–3963, 2004
Dielectric study of the phase diagram of the poly(γ‐benzyl‐L‐glutamate)/dimethylformamide system
Authors: Dereszewska A. , Alegria A. , Olayo R.
Published: September 2004

The phase diagram for solutions of poly(γ‐benzyl‐L‐glutamate) in dimethylformamide has been investigated over the entire composition and temperature ranges with dielectric spectroscopy. The dielectric response in this system is dominated by ionic mobility, and phase transitions have been detected as changes in the ionic conductivity. The phase boundaries, determined by dielectric spectroscopy, are consistent with earlier published results obtained by a combination of optical microscopy observations and nuclear magnetic resonance and differential scanning calorimetry studies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3943–3952, 2004
A Moving Average Control Chart for Monitoring the Fraction Non‐conforming
Authors: Khoo Michael B. C.
Published: September 2004

The p chart is often used to monitor the fraction of non‐conforming products. However, the p chart is slow in detecting sustaining shifts of small magnitude in the level of fraction non‐conforming. This paper discusses a more efficient alternative to the standard p chart approach, i.e. the construction of a moving average control chart for fraction non‐conforming, p. Approximations by means of mathematical calculations and the corresponding simulation results for the average run length profiles show that the performance of the new approach is superior to that of the standard approach. The new approach is easy to implement and hence might be attractive and useful to practitioners. Examples are also given to show how the proposed procedure is put to work in real situations. Copyright © 2004 John Wiley & Sons, Ltd.
The ability of the Gaussian‐2, Gaussian‐3, Complete Basis Set–QB3, and Complete Basis Set–APNO model chemistries to model the geometries of small water clusters
Authors: Dunn Meghan E. , Pokon Emma K. , Shields George C.
Published: September 2004

The Gaussian‐2, Gaussian‐3, Complete Basis Set‐QB3, and Complete Basis Set‐APNO methods have been used to calculate geometries of neutral clusters of water, (H2O)n, where n = 2–6. The structures are in excellent agreement with those determined from experiment and those predicted from previous high‐level calculations. These methods also provide excellent thermochemical predictions for water clusters, and thus can be used with confidence in evaluating the structures and thermochemistry of water clusters. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
A study of ring‐substituent influence on pharmacological activity in a series of phenethylamine‐type psychedelics
Authors: King James W. , Molnar Stephen P.
Published: September 2004

Geometry optimization for each member of a series of 15 substituted phenethylamines with reported psychotomimetic activity was performed using MM2 and MOPAC93 (AM1) methods. This was followed by calculation of previously developed, numerically unitary structure indices, viz., the molecular transform indices FTm, FTe, and FTc, indicating general, electronic, and charge properties respectively, and the analogous normalized molecular moment indices Mn, Me, and Mc. Each of the indices was used independently with the pharmacological data in a procedure to generate clusters containing three or more data points; linear correlations within each cluster were then determined. The Mn index performed best under the criteria, giving three clusters containing a total of 10 compounds; the other indices gave clusters accounting for totals of five to eight compounds for each index. Analysis of the clusters indicated that the 2‐ and 5‐positions on the phenyl ring should have substituents and that substitution at the 4‐position, preferably with a halogen, methyl, or thioether group, was critical for maximum pharmacological activity. The latter results suggest that ease of metabolic hydroxylation at the 4‐phenyl position (or the substituent group at that position, e.g., methyl, ethyl, etc.) is necessary for maximum activity. The performance of the Mn index appears to indicate more of a dependence on 3D spatial requirements for bioactivity, with molecular electronic and charge properties, respectively, being of secondary importance. Further, clustering and correlation regression of the biological data on the calculated logarithm of the octanol/water partition coefficient (CLogP) showed that the latter may be an important factor influencing pharmacological activity in this series. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Are managers from Mars and academicians from venus? Toward an understanding of the relationship between academic quality and practical relevance
Authors: Baldridge David C. , Floyd Steven W. , Markóczy Lívia
Published: September 2004

In this paper, we propose a positive relationship between the academic quality and practical relevance of management research. The basis for this is the idea that academicians and practitioners both value research that is interesting and justified—meaning research that challenges and extends existing beliefs and research that offers compelling evidence for its conclusions. We acknowledge that there are likely to be many cases where academicians and practitioners disagree on what is interesting and justified. We argue, however, that there are also likely to be cases where the judgments of the two groups converge. Results from a stratified, random sample of 120 publications are consistent with this argument—showing a positive correlation between an objective measure of an article's academic quality and expert panel ratings of its practical relevance. The analysis also shows positive associations between panel members' global assessment of relevance and ratings of an article's interestingness and justification. These results lend support to the hypothesized overlap, but leave room for considerable difference in the way practitioners and academicians evaluate management research. Copyright © 2004 John Wiley & Sons, Ltd.
The formation of green strategies in Chinese firms: matching corporate environmental responses and individual principles
Authors: Branzei Oana , Ursacki‐Bryant Teri Jane , Vertinsky Ilan , Zhang Weijiong
Published: September 2004

This study examines how Chinese firms began responding to worsening environmental concerns in the late 1990s. Combining predictions from control theory, escalation of commitment, and goal theory, we seek to explain how leaders' cognitions shape the formation of novel responses to the value‐laden issue of corporate greening. We propose an iterative model that links leaders' principles with corporate actions and test it using survey data gathered from 360 firms. The model views strategy organically, as a set of adaptive goals and behaviors, and highlights the role of systemic and local feedback loops in strategy formation. We find that top executives who champion new strategic initiatives monitor early success or failure, and adjust their efforts to match early performance feedback. Perceptions of satisfactory performance strengthen leaders' efforts towards their initial target, while perceptions of unsatisfactory performance diminish them. This feedback relationship is invariant throughout favorable or unfavorable expectancies of success, contrary to the contingent prediction of control theory. The model also examines how top‐down and bottom‐up strategic initiatives combine to help firms maintain a positive momentum of change when champions' efforts decline in the face of premature failure signals. Copyright © 2004 John Wiley & Sons, Ltd.
Firms' technological resources and the performance effects of diversification: a longitudinal study
Authors: Miller Douglas J.
Published: September 2004

While agency theory claims managerial self‐interest creates a diversification discount, strategic theory explains that firms with certain kinds of resources should diversify. Longitudinal data on 227 firms that diversify between 1980 and 1992 reveal that the sample firms invest less in R&D and have greater breadth of technology (based on patent citations) than their industry peers prior to the diversification event. Also, acquiring firms may appear to have lower performance because of accounting conventions and because firms that use internal growth rather than acquisition pursue less extensive diversification. These findings help explain how diversification and financial performance are endogenous. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐additivity in portfolios of exploration activities: a real options‐based analysis of equity alliances in biotechnology
Authors: Vassolo Roberto S. , Anand Jaideep , Folta Timothy B.
Published: September 2004

Firms invest in exploration‐oriented activities to seek competitive advantage and in response to changing environments. Real options formulations represent an emerging strand of thinking on such investments. In this paper we begin with the observation that firms often simultaneously invest in multiple exploration projects. We identify two sources of potential interactions among these real options investments. First, we investigate the effects of correlations between the outcomes in different options. Second, we analyze the effects of investments that are fungible across project options. We show that under different conditions multiple options can be sub‐additive (due to redundancies in outcomes) or super‐additive (due to fungible inputs). We test the implications of our model with data from the biotech industry and find supporting evidence. Our model and results have some interesting implications for the exploration literature and real options lens. Copyright © 2004 John Wiley & Sons, Ltd.
Writing in a foreign language: teaching and learning
Authors: O'Brien Teresa
Published: September 2004

This article is organised in five parts. The introduction defines the area covered and gives the rationale for a focus on FL writing research particularly in classroom contexts. The second section gives an overview of cognitive and social theoretical frameworks, noting that these have mainly been developed for L1 writing, and drawing attention to recent attempts to build models for FL writing. The third part covers research on process-based instruction, on teacher and peer feedback and on grammar correction. Part four deals with the growing use of computers in the teaching and learning of FL writing, looking particularly at work on word processing, software for teaching and research, at the relationships between network-based language teaching and process-oriented pedagogy and between writing and the development of oral communicative competence. The final part comments on research approaches, on FL writing and second language acquisition, and on post-process theory, concluding with a set of pedagogically-oriented research questions for the future.
Current lexicographical tools in EFL: monolingual resources for the advanced learner
Authors: Rizo-Rodríguez Alfonso
Published: September 2004

A rich variety of lexicographical descriptions is available in English, and there is no doubt that this contributes to its status as a world language. The teaching and learning of English can draw not only on a deep-rooted tradition of varied grammatical studies but also on a large range of dictionaries. For the non-native observer conversant with the nature of this language, its history, its development, its vocabulary and grammar, that huge stock of lexicographical resources is particularly useful.
The discovery and role of ADAM33, a new candidate gene for asthma
Authors: Holloway John W. , Keith Tim P. , Davies Donna E. , Powell Robert , Haitchi Hans-Michael , Holgate Stephen T.
Published: September 2004

Asthma is a complex disorder in which major genetic and environmental factors interact to initiate the disease and propagate it as a chronic relapsing disorder. Until recently, genetic factors implicated in the disease pathogenesis have been restricted to variants in known molecules involved in the inflammatory or remodelling pathways. This review discusses evidence for a new susceptibility gene for asthma, ADAM33, which was identified by positional cloning and shown to be selectively expressed in mesenchymal but not immune or inflammatory cells. ADAM33 belongs to a family of membrane–anchored metalloproteinases that also have fusagenic, adhesion and intracellular signalling properties. ADAM33 might play a key role in predisposing to the reduced lung function characteristic of asthma, possibly by influencing airway wall remodelling.
Tumour-targeted drug and gene delivery: principles and concepts
Authors: Cassidy Jim , Schätzlein Andreas G.
Published: September 2004

Delivery systems for tumour targeting fall into two basic categories: drug conjugate systems, in which individual drug molecules are chemically modified to target them directly to the tumour; and carrier-based systems, in which the drug or gene is first packaged non-covalently into a synthetic carrier that is then targeted to the tumour. In both cases, the objective is to maximise exposure of the target cells to the drug yet minimise side effects that result from nonspecific toxicity in normal tissues. The creation of such dose differentials is based on phenotypic differences between the tumour and the rest of the body. However, although a wide range of such changes have been linked to the transformation of normal cells to cancer cells, no single common feature exists to allow unambiguous targeting to the tumour. In addition, the tumour microenvironment creates physical barriers that significantly impair transport within the tumour. It is therefore important to match the delivery requirements of the drug to the capabilities of the delivery system. In this review, a brief overview is given of the underlying concepts and principles that help guide the development of such tumour-targeting strategies.
IALL Conference, Cape Town, September 2003 Meeting History in South Africa
Authors: Fishleigh Jackie
Published: September 2004

Jackie Fishleigh, Zosia Carson and Jean Lloyd were the lucky recipients of BIALL bursaries to enable them to attend the IALL Conference. The following are their accounts of different experiences they enjoyed during their trips.
Librarians Rule!!
Authors: Lloyd Jean
Published: September 2004

I'm sure that I speak for the three of us who were lucky enough to attend this year's IALL conference when I say that it was one of the most intense, interesting and enjoyable of experiences. Intense because of the nature of the subject matter of the conference, interesting because it was a country which none of us had visited before and enjoyable because of the people, the social events and the weather.
Greenhouse gas emissions from reservoirs of the western United States
Authors: Soumis Nicolas , Duchemin Éric , Canuel René , Lucotte Marc
Published: September 2004

Six reservoirs located in the Western United States (F. D. Roosevelt, Dworshak, Wallula, Shasta, Oroville, and New Melones) were sampled in order to estimate their greenhouse gas (GHG) emissions. Two types of fluxes were assessed: (1) diffusive fluxes of methane (CH4) and carbon dioxide (CO2) at the air/water interface and (2) degassing fluxes of CH4 and CO2 from water passing through the turbine spillways. Diffusive flux measurements indicated that the surface of the reservoirs were a source of CH4 during the sampling period (from +3.2 to +9.5 mg CH4 m−2 d−1). Oroville (+1026 mg CO2 m−2 d−1) and Shasta (+1247 mg CO2 m−2 d−1) surfaces were also sources of CO2. In contrast, the surface of all the other reservoirs constituted sinks for CO2 (from −349 to −1195 mg CO2 m−2 d−1). Degassing fluxes ranged from +0.003 to +0.815 t CH4 d−1, and from +16 to +324 t CO2 d−1. Daily GHG budgets ranged from +0.146 to +2.228 t CH4 d−1, and from −15 to +224 t CO2 d−1. Degassing fluxes represented an important term of these budgets. A significant correlation was observed between the magnitude of CO2 diffusive fluxes and the water pH (R2 = 0.81; p < 0.0001). All other correlations between GHG diffusive fluxes and independent variables tested were weak and/or not significant. Finally, while attempting to resolve the spatial variability in diffusive fluxes, we were able to cluster reservoirs neither according to geological nor ecological criteria.
Basal shear stress of the Ross ice streams from control method inversions
Authors: Joughin Ian , MacAyeal Douglas R. , Tulaczyk Slawek
Published: September 2004

We used control method inversions to determine the basal shear stress beneath the Ross ice streams where new high‐resolution velocity data sets have recently become available. The inversion algorithm was adapted from an earlier viscous bed algorithm to allow solution for the basal shear stress corresponding to a weak plastic bed. We performed several experiments using synthetic data to determine the quality of the inversions. These experiments indicate that with high‐quality surface elevation data (e.g., errors <5 m), the inversions are relatively robust with respect to errors in ice flow velocity and bed topography. The inversions are consistent with seismic and borehole observations and indicate that the Ross ice streams lie atop a bed that is nearly everywhere weak. In contrast, the tributaries feeding these ice streams overlie alternating patches of strong and weak bed.
Modeling unsteady turbulent flows over ripples: Reynolds‐averaged Navier‐Stokes equations (RANS) versus large‐eddy simulation (LES)
Authors: Chang Yeon S. , Scotti Alberto
Published: September 2004

In this paper we consider the problem of modeling a turbulent pulsating boundary layer over ripples. We compare the results of two modeling strategies, Wilcox's k − ω Reynolds‐Averaged Navier‐Stokes equations (RANS) and large‐eddy simulation (LES) employing the Lagrangian dynamic eddy viscosity model. The geometry and parameters employed are relevant to nearshore oceanic flows, and the results are discussed in relation to the problem of sediment transport. Generally, RANS and LES agree well only with regard to the vertical profiles of the streamwise component of the velocity. Large discrepancies were found in all the other quantities considered (e.g., vertical velocity, turbulent kinetic energy, and Reynolds stress). In particular, RANS severely underpredicted the magnitude of the Reynolds stress and overpredicted the amplitude of the oscillations in the vertical velocity. We also found that often the trends exhibited by RANS and LES when the frequency and/or amplitude of the driving conditions was varied were at odds. Since comparison with available experiments indicates that LES is able to accurately model this kind of flows, we conclude that the RANS model is not appropriate to model the suspension and transport of sediment under conditions similar to the ones presented in this study.
Thresholds for warming‐induced growth decline at elevational tree line in the Yukon Territory, Canada
Authors: D'Arrigo Rosanne D. , Kaufmann Robert K. , Davi Nicole , Jacoby Gordon C. , Laskowski Cheryl , Myneni Ranga B. , Cherubini Paolo
Published: September 2004

A few tree ring studies indicate recent growth declines at northern latitudes. The precise causes are not well understood. Here we identify a temperature threshold for decline in a tree ring record from a well‐established temperature‐sensitive site at elevational tree line in northwestern Canada. The positive ring width/temperature relationship has weakened such that a pre‐1965 linear model systematically overpredicts tree ring widths from 1965 to 1999. A nonlinear model shows an inverted U‐shaped relationship between this chronology and summer temperatures, with an optimal July–August average temperature of 11.3°C based on a nearby station. This optimal value has been consistently exceeded since the 1960s, and the concurrent decline demonstrates that even at tree line, trees can be negatively affected when temperatures warm beyond a physiological threshold. If warming continues without significant gains in effective precipitation, the large‐scale greening of recent decades could be replaced by large‐scale browning. Such browning could slow or reverse carbon uptake by northern forests.
Does within‐bog spatial variability of mercury and lead constrain reconstructions of absolute deposition rates from single peat records? The example of Store Mosse, Sweden
Authors: Bindler Richard , Klarqvist Malin , Klaminder Jonatan , Förster Johannes
Published: September 2004

Recent research has recognized the utility of the peat record in ombrotrophic bogs to reconstruct past changes in the atmospheric deposition of, for example, lead and mercury. Frequently, these reconstructions rely only on single peat records to make assessments of regional deposition rates. The surface of a bog is not a uniform feature; rather, vegetation and micro‐topography vary over small spatial scales, which can affect the interception and retention of atmospheric deposition, and over relatively short timescales. Analyses of nine hummock cores collected from a 2000 m2 area on one bog, Store Mosse, show that concentrations and cumulative inventories (past 110 years) of lead and mercury vary by a factor of 2 for lead (0.75 to 1.40 g Pb m−2, three cores) and 4 for mercury (0.85 to 3.4 mg Hg m−2, nine cores). The range of values within Store Mosse is greater than the difference between any one core and the metal inventories from either Dumme Mosse (0.95 g Pb m−2 and 2.0 mg Hg m−2) or Trollsmosse (1.6 mg Hg m−2), each about 60 km distant. Although the general temporal trends are similar in all cores, our data indicate that single reconstructions do not necessarily provide a representative flux for the bog as a whole. To overcome the potential constraints of single records, we suggest incorporating data from multiple sites or at least multiple cores in order to scale up to regionally valid models of past metal deposition.
Volcanic sources of tropospheric ozone‐depleting trace gases
Authors: Gerlach T. M.
Published: September 2004

Recent investigations report mixing ratios of BrO gas reaching 1 ppb in plume 4–7 km downwind of the summit of Soufrière Hills volcano, Montserrat. The detection of BrO in volcanic plumes is potentially important evidence of halogen‐catalyzed tropospheric ozone destruction and suggests that volcanoes either directly emit BrO or emit bromine species that are rapidly converted to reactive bromine in volcanic plumes. Species distribution models constrained by volcanic gas and condensate analytical data for arc, rift, and hot spot volcanoes demonstrate that shallow magma degassing generates volcanic gases with ppb to ppm levels of reactive radicals Br, Cl, H, and HO but no significant BrO or ClO. The conversion of volcanic Br and Cl by reaction with ozone in gas‐phase catalytic reaction cycles during plume transport can lead to secondary BrO and ClO at mixing ratios of a ppt and higher, possibly approaching a ppb for especially halogen‐rich volcanic gases, several kilometers downwind of degassing sources. In general, however, ppb BrO and ClO levels in volcanic plumes several kilometers downwind probably require near‐vent, high‐temperature reaction of magmatic gases with air and/or in‐plume heterogeneous chemical processes involving aerosols during plume transport. These processes oxidize bromine and chlorine in HBr and HCl, giving rise to increased levels of reactive Br, Cl, and HO, in addition to NOx. They can also produce significant amounts of the photochemically active precursors Br2, BrCl, and Cl2, which are photolyzable to reactive Br and Cl. The precursors may build up in nighttime volcanic plumes and accelerate ozone destruction and BrO and ClO production after sunrise. Downwind conversion of reactive Br, Cl, H, and HO from volcanic gas sources by catalytic reaction chains to HOBr and HOCl may trigger heterogeneous chemical processes, which are probably essential for sustaining ozone destruction in volcanic plumes. Gas‐phase reactions of HBr and HCl with HO in volcanic plumes might also boost BrO and ClO downwind. Thus in‐plume processes that generate reactive halogens may contribute significantly to ozone destruction in volcanic plumes. Enhanced levels of HOx and NOx in volcanic emissions may trigger nonhalogen catalytic cycles depleting ozone in tropospheric volcanic plumes.
Distant magnetotail reconnection and the coupling to the near‐Earth plasma sheet: Wind and Geotail case study
Authors: Øieroset Marit , Phan Tai D. , Fujimoto Masaki , Lin Robert P.
Published: September 2004

We have studied the coupling between the distant and near‐Earth plasma sheet during an 8 hour interval on April 1, 1999 when the interplanetary magnetic field was northward and dominated by the By component. During these 8 hours the Geotail spacecraft sampled the near‐Earth magnetotail at XGSM ∼ −25 RE while the Wind spacecraft was located in the distant magnetotail at XGSM ∼ −60 RE. Wind detected long duration (>8 hours) and likely spatially extended convective high speed flows indicative of continuous magnetic reconnection, whereas only plasma sheet boundary layer beams and some locally generated bursty bulk flows were observed at the Geotail location. Hence the high speed distant tail reconnection flows did not reach the near‐Earth plasma sheet at high speed. No apparent signatures of the long duration distant tail reconnection flows in terms of global and auroral geomagnetic activity were observed.
Seasonal modulation of GPS performance due to equatorial scintillation
Authors: Thomas R. M. , Cervera M. A. , Ramli A. Ghaffar , Effendy  , Totarong P. , Groves K. M. , Wilkinson P. J.
Published: September 2004

Evening scintillation is an aspect of space weather occurring primarily in the equatorial region due to scattering of satellite signals by ionospheric F‐region irregularities. In order to quantify scintillation‐related performance degradation in GPS (Global Positioning System), we operated single frequency (L1) Ionospheric Scintillation Monitors (ISM), sampling at 50 Hz, at 6 sites in the South East Asia/Oceania region during the most recent solar maximum period 1998–2002. Scintillation indices, horizontal position, receiver lock time and dilution of precision were recorded every minute. Data reveal that individual one‐minute positional errors can increase from a few meters to 30 m during scintillation, whilst statistics at the hourly upper decile level reveal an underlying seasonal modulation from about 5 m to 15 m. Error maxima occur during the equinoxes and are more pronounced at the equatorial anomaly crests than at the magnetic equator, as expected. Such errors may concern users of systems that are dependent on GPS.
Ocean circulation and climate in an idealised Pangean OAGCM
Authors: Smith R. S. , Dubois C. , Marotzke J.
Published: September 2004

An idealised Pangean configuration is integrated in a coupled ocean atmosphere general circulation model to investigate the form of the ocean circulation and its impacts on the large scale climate system. A vigorous, hemispherically symmetric overturning is found, driven by deep water formation at high latitudes. Whilst the peak mass transport is around 100 Sv, a low vertical temperature gradient in the ocean means that the maximum heat transport is only 1.2 PW. The geographical change in the coupled model is found to produce a global average warming of 2°C, despite an increase in global surface albedo. This occurs through changes in the atmospheric water vapour and cloud distributions. There is also reduction in the equator‐pole temperature gradient, largely attributable to the same causes, avoiding the paradox of low meridional temperature gradients without increased polar heat transport.
Antarctic stratospheric ozone from the assimilation of occultation data
Authors: Stajner Ivanka , Wargan Krzysztof
Published: September 2004

Ozone data from the solar occultation Polar Ozone and Aerosol Measurement (POAM) III instrument are included in the ozone assimilation system at NASA's Global Modeling and Assimilation Office, which uses Solar Backscatter UltraViolet/2 (SBUV/2) instrument data. Even though POAM data are available at only one latitude in the southern hemisphere on each day, their assimilation leads to more realistic ozone distribution throughout the Antarctic region, especially inside the polar vortex. Impacts of POAM data were evaluated by individual and statistical comparisons of assimilated ozone profiles with independent ozone sondes. Major improvements in ozone representation are seen in the Antarctic lower stratosphere during austral winter and spring in 1998. Limitations of assimilation of sparse occultation data are illustrated by an example.
Role of internal waves in the generation of nepheloid layers on the northwestern Alboran slope: Implications for continental margin shaping
Authors: Puig P. , Palanques A. , Guillén J. , El Khatab M.
Published: September 2004

The role of internal waves in the sediment dynamics of the northwestern Alboran continental slope was investigated in a selected area around the Guadiaro submarine canyon. Nepheloid layer distribution was identified using closely spaced CTD/transmissometer profiles collected during two hydrographic surveys. A well‐defined pattern of suspended sediment distribution consisting of surface, intermediate, and near‐bottom nepheloid layers was found. Intermediate and bottom nepheloid layers were always observed within the canyon and on the adjacent continental slope, spanning mainly from 200 to 500 m depth. In addition, a current meter with a turbidimeter was deployed in the lower section of the Guadiaro Canyon at 600 m depth, 25 meters above the seafloor. Time series analysis indicated that the currents, temperature, and turbidity within the canyon fluctuate mainly at semidiurnal tidal frequencies, suggesting the presence of semidiurnal internal tides affecting the near‐bottom suspended sediment concentration along the canyon axis. High‐resolution bathymetry from the study area was used to evaluate the internal wave reflection conditions at semidiurnal tidal frequency for the entire continental slope region. Critical slope conditions were reached on the upper continental slope and along the canyon axis, coinciding with the region in which nepheloid layers were observed. This region also coincides with a zone of erosion on the upper continental slope of the study area previously identified by Hernández‐Molina [1993]. These results indicate that the generation of intermediate and bottom nepheloid layers, as well as the erosion and shaping of the northwestern Alborán continental slope, may result from the interaction of internal waves and the seafloor morphology.