bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of convective flows in cavities: solution of benchmark problems by a low‐order finite volume method
Authors: Gelfgat Alexander Yu. 
Published: August 2006

AbstractA problem of stability of steady convective flows in rectangular cavities is revisited and studied by a second‐order finite volume method. The study is motivated by further applications of the finite volume‐based stability solver to more complicated applied problems, which needs an estimate of convergence of critical parameters. It is shown that for low‐order methods the quantitatively correct stability results for the problems considered can be obtained only on grids having more than 100 nodes in the shortest direction, and that the results of calculations using uniform grids can be significantly improved by the Richardson's extrapolation. It is shown also that grid stretching can significantly improve the convergence, however sometimes can lead to its slowdown. It is argued that due to the sparseness of the Jacobian matrix and its large dimension it can be effective to combine Arnoldi iteration with direct sparse solvers instead of traditional Krylov‐subspace‐based iteration techniques. The same replacement in the Newton steady‐state solver also yields a robust numerical process, however, it cannot be as effective as modern preconditioned Krylov‐subspace‐based iterative solvers. Copyright © 2006 John Wiley & Sons, Ltd.
Dynamics of large solid particles in bioconvective sedimentation
Authors: Geng P. , Kuznetsov A. V. 
Published: August 2006

AbstractSettling of one or two large solid particles in a bioconvection flow induced by gyrotactic motile microorganisms is investigated using a 2D numerical model. The results of varying the initial positions of large particles on the bioconvection flow pattern are investigated. The Chimera method is utilized to generate subgrids around the moving particles. It is demonstrated that the introduction of a single large particle displaces bioconvection plume and changes its shape. The introduction of two particles on the same side of the bioconvection plume further displaces the plume while the introduction of two particles on opposite sides reduces this displacement. The influence of the bioconvection plume on the particles' settling paths and particles' settling velocities is investigated. Copyright © 2006 John Wiley & Sons, Ltd.
Optimization of heat‐transfer rate into time‐periodic two‐dimensional Stokes flows
Authors: Mota J. P. B. , Rodrigo A. J. S. , Saatdjian E. 
Published: August 2006

AbstractThe periodic boundary displacement protocol leading to the optimum wall‐to‐fluid heat‐transfer rate, or to the most efficient mixing rate, in 2‐D annular Stokes flows is determined by calculating the steady periodic velocity and temperature fields. To obtain the steady periodic state one usually solves the dynamical system obtained after the spatial coordinates have been discretized. Here, we calculate the steady periodic state using an implicit method based on the discretization of the time coordinate over a period and the asymptotic regime is enforced by the periodicity condition in the computed temperature field. The obtained system of equations is solved using a Newton‐type iterative algorithm with invariant Jacobian. At each iteration step, the sparse linearized system is solved using a multi‐grid algebraic technique of rapid convergence. From a computational point of view and for the problem considered here, this method is an order of magnitude faster than the one based on a spatial discretization. Copyright © 2006 John Wiley & Sons, Ltd.
Topographical recognition memory sensitive to amnestic mild cognitive impairment but not to depression
Authors: Ritter Emilie , Després Olivier , Monsch Andreas U. , Manning Lilianne 
Published: August 2006

AbstractObjectiveAmnestic mild cognitive impairment (aMCI) involves episodic memory. The person who presents aMCI has a high risk of developing Alzheimer's disease (AD). However, prediction of deterioration to dementia in cases of aMCI can be confounded with depression due to lack of specificity on selective memory tests. Finding a test sensitive to aMCI but not to depression would be potentially most useful to subsequent longitudinal studies researching the neuropsychological markers of preclinical AD. We hypothesized that the performance on a topographical memory task would be sensitive to the aMCI condition, while depression would not influence such a performance.Participants and MethodsA group of 137 community‐dwelling French‐speaking subjects between 55 and 70 years old was administered a topographical recognition memory task. Based on aMCI and depression criteria, 45 subjects were selected and divided into four groups: 11 patients with aMCI without depression, nine depressive patients with aMCI, ten depressive patients without cognitive impairment and 15 control subjects. The remaining non‐selected participants did not belong to any of the previous interest groups.ResultsThe ‘aMCI’ factor had a significant effect on the topographical recognition memory task scores, while the ‘depression’ factor did not. The aMCI patients performed worse than the non‐aMCI.ConclusionAlthough these results were found with relatively small groups, deficits in topographical recognition memory were observed in aMCI patients and did not seem to be sensitive to depression. Further longitudinal studies are needed to examine whether deficits in topographical recognition memory are a neuropsychological marker of preclinical AD. Copyright © 2006 John Wiley & Sons, Ltd.
Investigating the quitting decision of nurses: panel data evidence from the british national health service
Authors: Frijters Paul , Shields Michael A. , Price Stephen Wheatley 
Published: August 2006

AbstractIn this paper, we provide a detailed investigation into the quitting behaviour of nurses in the British National Health Service (NHS), using a recently constructed longitudinal survey. We fit both single and competing risks duration models that enable us to establish the characteristics of those nurses who leave the public sector, distinguish the importance of pay in this decision and document the destinations that nurses move to. Contrary to expectations, we find that the hourly wage received by nurses outside of the NHS is around 20% lower than in the NHS, and that hours of work are about the same. However, while the effect of wages is found to be statistically significant, the predicted impact of an increase in nurses' pay on retention rates is small. The current nurse retention problem in the NHS is therefore unlikely to be eliminated through substantially increased pay. Copyright © 2006 John Wiley & Sons, Ltd.
Origin and type of rainfall for recharge of a karstic aquifer in the western Mediterranean: a case study from the Sierra de Gador–Campo de Dalias (southeast Spain)
Authors: Frot Elisabeth , van Wesemael Bas , Vandenschrick Grégoire , Souchez Roland , Solé Benet Albert 
Published: August 2006

AbstractIsotope signatures in precipitation from the Global Network for Isotopes in Precipitation around the Mediterranean basin and literature data are compared with isotopic data from a large karstic aquifer in southeast Spain to explain the origin and type of the precipitation events dominating recharge. Analysis of the deuterium excess d at the scale of the Mediterranean basin and at the regional scale allows us to understand the isotopic context of the study area: Campo de Dalias and the Sierra de Gador (Almería province). The origin of precipitation can be determined from its d value. The d value changes as a function of the initial evaporation condition. It depends on the relative humidity and temperature during the evaporation producing the water vapour of the clouds. The water vapour, which dominates the study area, is generated in two areas: the Atlantic Ocean (d = 10‰) and the western Mediterranean basin (d = 15‰). With increasing precipitation volume, the western Mediterranean character dominates. These heavier storms contribute mainly to recharge, as illustrated by the d value of 13·6‰ in deep groundwater of the Campo de Dalias. Weighted d values increase with the volume of precipitation, giving a significant relationship for the southern and eastern coasts of the Iberian Peninsula. This selectivity of d to monthly precipitation was used to estimate the return period of precipitation leading to aquifer recharge at 0·9–4·9 years. Moderate rainfall, which occurs more frequently, still represents ∼60–90% of the total precipitation. One of the challenges to meet ever‐growing water demands is to increase recharge from moderate events yielding intermediate quantities per event, but forming the bulk of the annual precipitation. Copyright © 2006 John Wiley & Sons, Ltd.
Climatic and topographic limits to the abundance of bog pools
Authors: Belyea Lisa R. 
Published: August 2006

AbstractOn patterned peatlands, open water pools develop within a matrix of terrestrial vegetation (‘ridges’). Regional patterns in the distribution of ridge–pool complexes suggest that the relative cover of these two surface types is controlled in part by climate wetness, but landscape topography must also be an important controlling factor. In this paper, a functional model that relates relative cover of ridges and pools to climate and surface gradient was developed and tested. The model was formulated in terms of a water budget, based on the differential effects of ridges and pools on losses by evapotranspiration and subsurface flow. It predicts a positive relationship between surface gradient and ridge proportion, with a linear effect related to water supply and ridge hydraulic conductivity, modified at high ridge proportion by differences in evapotranspiration between ridges and pools. The limit to patterned peatland distribution occurs where the surface is completely covered by ridges. The model may be sensitive or insensitive to climate differences between localities, depending on whether hydraulic characteristics of ridge peat co‐vary with water supply. To distinguish between these alternative hypotheses, surface gradient and ridge proportion were surveyed along 20 transects in each of three localities in Scotland that differ threefold in net precipitation to pools. The results of the field survey served to reject the climate‐sensitive hypothesis, but were consistent with the climate‐insensitive hypothesis. Analysis of the residuals suggested that variation within localities was related more to topographic control of water supply than to ridge hydraulic conductivity or developmental stage. Hence, within this maritime climate region, the distribution of ridge–pool complexes and the relative abundance of pools are controlled mainly by topographic variables. Field surveys across both maritime and continental regions are required to confirm a subtle climatic effect that allows pools to occur on higher gradients in drier climates than in wetter climates. Further development and testing of the functional model will provide a stronger basis for assessing potential feedback between climate change, peatland surface structure and methane emission from pools. Copyright © 2006 John Wiley & Sons, Ltd.
Studies on groundwater recharge characteristics at a reclaimed land site with an equatorial climate using time‐series and spectral analyses
Authors: Tan Stephen Boon Kean , Shuy Eng Ban , Chua Lloyd Hock Chye , Yee Woon Kang 
Published: August 2006

AbstractGroundwater recharge studies are essential for investigating the feasibility of using the reclaimed lands in Singapore for subsurface storage and recovery of water. Through time‐series and spectral analyses, net recharge percentages and stress‐filtering characteristics at the reclaimed land were found to depend strongly on the stress transfer velocity, which was a combined function of rainfall pattern and vadose zone thickness. Based on stress transfer velocity, a theory was established to provide logical explanations for the rainfall–recharge relationship, the observed stress‐filtering characteristics and the recharge percentage characteristics at the unconfined sandy aquifer. Although the reclaimed land site has a lithollogically homogeneous soil profile, a non‐uniform recharge pattern was observed to be influenced pronouncedly by the uneven density distribution of bush grasses. Under a bare soil condition, significantly lower recharge percentages were observed for areas under the influence of offshore tides. The unconfined sandy aquifer appears to dampen out the wave propagation of offshore tides rapidly within a short distance from the tidal source, though it has a fairly straight shoreline and is created from highly compacted sand fills. Copyright © 2006 John Wiley & Sons, Ltd.
Impact of cyclins E, neutrophil elastase and proteinase 3 expression levels on clinical outcome in primary breast cancer patients
Authors: Desmedt Christine , Ouriaghli Frank El , Durbecq Virginie , Soree Anne , Colozza Maria Antonetta , Azambuja Evandro , Paesmans Marianne , Larsimont Denis , Buyse Marc , Harris Adrian , Piccart Martine , Martiat Philippe , Sotiriou Christos 
Published: August 2006

AbstractUncontrolled cell proliferation is one of the hallmarks of cancer and the transition from the G1 to S phase is the most commonly reported cell cycle abnormality in tumors. It has been shown that the oncogenic activity of G1 cyclin E (CCNE) can be amplified by generating hyperactive low molecular weight forms (LMW) through elastase‐mediated proteolytic processing. Neutrophil elastase (NE) and proteinase 3 (PR3) are 2 proteases that are aberrantly expressed in breast cancer cells and seem to be involved in cell proliferation. In this study, we evaluated the effect of the expression of these 2 proteases in addition to 2 potential intracellular targets of NE (CCNE1 and CCNE2) on clinical outcome in a population of 205 primary breast cancer patients. By univariate analysis, CCNE1, CCNE2, estrogen receptor and grade significantly predicted relapse free interval (RFI). NE and PR3 did not achieve statistical significance. In a multivariate analysis, elevated CCNE2 [hazard ratio (HR) 2.10, p = 0.008] predicted shorter RFI. In subgroup analyses of the tamoxifen‐only treated patients, high CCNE1 levels predicted treatment resistance, while high levels of CCNE2 were associated with poor RFI in untreated patients. Investigation of the relationship between CCNE1, CCNE2 and NE did not show any impact on RFI. To conclude, this study was the first to evaluate these markers at the mRNA level by RT‐PCR in a series of primary breast cancer patients, and our results confirmed the impact of high CCNE levels on clinical outcome in systemically untreated and of CCNE1 in tamoxifen‐only treated early breast cancer patients. © 2006 Wiley‐Liss, Inc.
Cancer mortality rates among first and second generation migrants in the Netherlands: Convergence toward the rates of the native Dutch population
Authors: Stirbu Irina , Kunst Anton E. , Vlems Femke A. , Visser Otto , Bos Vivian , Deville Walter , Nijhuis Haarry G.J. , Coebergh Jan W. 
Published: August 2006

AbstractThis study investigates the difference in cancer mortality rates between migrant groups and the native Dutch population, and determines the extent of convergence of cancer mortality rates according to migrants' generation, age at migration and duration of residence. Data were obtained from the national cause of death and population registries in the period 1995–2000. We used Poisson regression to compare the cancer mortality rates of migrants originating from Turkey, Morocco, Surinam, Netherlands Antilles and Aruba to the rates for the native Dutch. All‐cancer mortality among all migrant groups combined was significantly lower when compared to that of the native Dutch population (RR = 0.55, CI: 0.52–0.58). For a large number of cancers, migrants had more than 50% lower risk of death, while elevated risks were found for stomach and liver cancers. Mortality rates for all cancers combined were higher among second generation migrants, among those with younger age at migration, and those with longer duration of residence. This effect was particularly pronounced in lung cancer and colorectal cancer. For most cancers, mortality among second generation migrants remained lower compared to the native Dutch population. Surinamese migrants showed the most consistent pattern of convergence of cancer mortality. The generally low cancer mortality rates among migrants showed some degree of convergence but did not yet reach the levels of the native Dutch population. This convergence implies that current levels of cancer mortality among migrants will gradually increase in future years if no specific preventive measurements are taken. © 2006 Wiley‐Liss, Inc.
The thymidylate synthase tandem repeat promoter polymorphism: A predictor for tumor‐related survival in neoadjuvant treated locally advanced gastric cancer
Authors: Ott Katja , Vogelsang Holger , Marton Noemi , Becker Karen , Lordick Florian , Kobl Michael , Schuhmacher Christoph , Novotny Alexander , Mueller James , Fink Ulrich , Ulm Kurt , Siewert Jörg Rüdiger , Höfler Heinz , Keller Gisela 
Published: August 2006

AbstractWe evaluated DNA polymorphisms in the thymidylate synthase (TS) and 5,10‐methylene‐tetrahydrofolate reductase (MTHFR) genes for an association with response and survival in locally advanced gastric cancer treated with 5‐FU based preoperative chemotherapy (CTx). DNA of 238 patients (CTx‐group: total n = 135, completely resected (R0) n = 102; without CTx: R0 n = 103) was isolated from blood or from nontumorous tissues. In the CTx‐group, genotyping of the tandem repeat and the G/C polymorphism in the triple repeat in the promoter region of the TS gene and of the C677T polymorphism of the MTHFR gene was performed. None of the TS or MTHFR genotypes were associated with histopathological response and only the TS tandem repeat polymorphism was significantly related to survival (all patients n = 135, p = 0.002; R0 resected patients n = 102, p = 0.007; log‐rank test). Multivariate analysis revealed ypN (p < 0.001) and the TS tandem repeat polymorphism as independent prognostic factors in the CTx‐R0‐group (p = 0.003). Analyzing the prognostic significance of the TS polymorphisms in the R0‐group without CTx, TS genotypes were not significantly associated with survival. Comparing survival between R0 patients with and without CTx in the respective TS genotype groups of the tandem repeat polymorphism, a significant survival benefit for the patients with CTx was found for the 2rpt/2rpt (n = 49; p = 0.002) and 2rpt/3rpt genotypes (n = 99; p = 0.004), but not for the 3rpt/3rpt genotype (n = 57; p = 0.93). Patients' survival after CTx was associated with the TS tandem repeat polymorphism. CTx did not improve survival of patients with the 3rpt/3rpt genotype. Thus, a different therapy might be more appropriate for these patients. © 2006 Wiley‐Liss, Inc.
Covalently crosslinked chitosan hydrogel formed at neutral pH and body temperature
Authors: Hong Yi , Mao Zhengwei , Wang Hualin , Gao Changyou , Shen Jiacong 
Published: August 2006

AbstractWater‐soluble chitosan having double bonds (CS–MA–LA) was synthesized by sequential grafting of methacrylic acid (MA) and lactic acid (LA) via the reaction between amino groups and carboxyl groups under the catalysis of carbodiimide. Its molecular structure was verified by FTIR and 1H NMR characterizations. Elemental analysis measured grafting ratios of 19% and 10.33% for MA and LA, respectively. CS–MA–LA was readily soluble in pure water and did not precipitate till pH 9. Gelation of the CS–MA–LA was realized by thermal treatment at body temperature under the initiation of a redox system, ammonium persulfate (APS)/N, N,N′,N′‐tetramethylethylenediamine (TEMED). The gelation time could be mediated in a wide range, e.g. from 6 to 20 min, by reaction temperature and/or initiator's concentration. 3T3 fibroblast culture showed that the cytotoxicity of the hydrogel extractant was dependent on the cell seeding number and the initiator's concentration. With enough number of cells (>2.5 × 104) and low initiator's concentration (5 mM), the cytotoxicity introduced by the initiator is very minimal and negligible. Although the hydrogel could cause acute inflammation and foreign body reaction, no tissue necrosis and malignant infection were evidenced in vivo, demonstrating that the material has better histocompatibility. These features have endowed the chitosan with great opportunity as injectable biomaterials, which may find wide applications in the rapidly developed fields such as tissue engineering and orthopedics. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Controlled release of bioactive doxorubicin from microspheres embedded within gelatin scaffolds
Authors: DeFail Alicia J. , Edington Howard D. , Matthews Stacey , Lee Wen‐Chi C. , Marra Kacey G. 
Published: August 2006

AbstractWe have encapsulated the chemotherapeutic agent doxorubicin into biodegradable polymer microspheres, and incorporated these microspheres into gelatin scaffolds, resulting in a controlled delivery system. Doxorubicin was encapsulated in poly(D,L‐lactide‐co‐glycolide) (PLGA) using a double emulsion/solvent extraction method. Characterization of the microspheres including diameter, surface morphology, and in vitro drug release was determined. The release of doxorubicin up to 30 days in phosphate buffered solution was assessed by measuring the absorbance of the releasate solution. Gelatin scaffolds were crosslinked using glutaraldehyde and microspheres were added to gelatin during gelation. The murine mammary mouse tumor cell line, 4T1, was treated with various doses of doxorubicin. A propidium iodide assay was utilized to visualize dead cells. Using a Transwell basket assay, PLGA microspheres and gelatin constructs were suspended above 4T1 cells for 48 h. Viable cells were determined using the CyQUANT cell proliferation assay. Results indicate that the release was controlled by the incorporation of PLGA microspheres into gelatin constructs. A significant difference was seen in the cumulative release over days 5–16 (p < 0.05). The bioactivity of doxorubicin released from the microspheres and scaffolds was maintained as proven by significant reduction in viable cells after treatment with PLGA microspheres as well as with the gelatin constructs (p < 0.001). The drug‐polymer conjugate can be used as a controlled drug delivery system in a biocompatible scaffold that could potentially promote preservation of soft tissue contour. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006