bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amperometric Glucose Biosensor on Layer by Layer Assembled Carbon Nanotube and Polypyrrole Multilayer Film
Authors: Shirsat Mahendra D. , Too Chee O. , Wallace Gordon G. 
Published: October 2007

AbstractAn amperometric glucose biosensor on layer by layer assembled carbon nanotube and polypyrrole multilayer film has been reported in the present investigation. Homogeneous and stable single wall carbon nanotubes (SWNTs) and polypyrrole (PPy) multilayer films were alternately assembled on platinum coated Polyvinylidene fluoride (PVDF) membrane. Since conducting polypyrrole has excellent anti‐interference ability, protection ability in favor of increasing the amount of the SWNTs on platinum coated PVDF membrane and superior transducing ability, a layer by layer approach of polypyrrole and carbon nanotubes has provided an excellent matrix for the immobilization of enzyme. The layer‐by‐layer assembled SWNTs and PPy‐modified platinum coated PVDF membrane is shown to be an excellent amperometric sensor over a wide range of concentrations of glucose. The glucose oxidase (GOx) was immobilized on layer by layer assembled film by a physical adsorption method by cross linking through Glutaraldehyde. The glucose biosensor exhibited a linear response range from 1 mM to 50 mM of glucose concentration with excellent sensitivity of 7.06 μA/mM.
Least action principle, equilibrium states, iterative adjustment and the stability of alluvial channels
Authors: Nanson Gerald C. , Huang He Qing 
Published: October 2007

AbstractThe energy based least action principle (LAP) has proven to be very successful for explaining natural phenomena in both classical and modern physics. This paper briefly reviews its historical development and details how, in three ways, it governs the behaviour and stability of alluvial rivers. First, the LAP embodies the special stationary equilibrium state of motion and so its incorporation with the principle of energy conservation explains why so many optimizing hypotheses have been proposed in fluvial geomorphology. Second, the variational approach underlying the LAP provides a more straightforward and simpler fuzzy‐object orientated method for solving river regime problems than do the various complex Newtonian formulations. Third, it is shown that in fluvial systems with surplus energy the surplus can be expended with slope and/or channel geometry adjustments, with the degree of channel geometry adjustment quantified by the dimensionless numbers F for depth dominated adjustment and H for width/depth dominated adjustment. Different planforms are preferred at different energy levels, with H providing a quantitative measure of the flow's efficiency for moving sediment. In rivers with insufficient energy, the interactions of endogenous and exogenous factors are shown to be capable, in certain circumstances, of achieving a stationary equilibrium condition which acts as the attractor state. Importantly, this study describes how iterative changes enable systems to achieve such a stable equilibrium. Copyright © 2007 John Wiley & Sons, Ltd.
The measurement and modelling of rill erosion at angle of repose slopes in mine spoil
Authors: Hancock G. R. , Crawter D. , Fityus S. G. , Chandler J. , Wells T. 
Published: October 2007

AbstractThe process of rill erosion causes significant amounts of sediment to be moved in both undisturbed and disturbed environments and can be a significant issue for agriculture as well as mining lands. Rills also often develop very quickly (from a single rainfall event to a season) and can develop into gullies if sufficient runoff is available to continue their development. This study examines the ability of a terrestrial laser scanner to quantify rills that have developed on fresh and homogeneous mine spoil on an angle of repose slope. It also examines the ability of the SIBERIA erosion model to simulate the rill's spatial and temporal behaviour. While there has been considerable work done examining rill erosion on rehabilitated mine sites and agricultural fields, little work has been done to examine rill development at angle of repose sites. Results show that while the overall hillslope morphology was captured by the laser scanner, with the morphology of the rills being broadly captured, the characteristics of the rills were not well defined. The digital elevation model created by the laser scanner failed to capture the rill thalwegs and tops of the banks, therefore delineating a series of ill defined longitudinal downslope depressions. These results demonstrate that an even greater density of points is needed to capture sufficient rill morphology. Nevertheless, SIBERIA simulations of the hillslope demonstrated that the model was able to capture rill behaviour in both space and time when correct model parameters were used. This result provides confidence in the SIBERIA model and its parameterization. The results demonstrate the sensitivity of the model to changes in parameters and the importance of the calibration process. Copyright © 2007 John Wiley & Sons, Ltd.
Relation between flow, surface‐layer armoring and sediment transport in gravel‐bed rivers
Authors: Pitlick John , Mueller Erich R. , Segura Catalina , Cress Robert , Torizzo Margaret 
Published: October 2007

AbstractThis study investigates trends in bed surface and substrate grain sizes in relation to reach‐scale hydraulics using data from more than 100 gravel‐bed stream reaches in Colorado and Utah. Collocated measurements of surface and substrate sediment, bankfull channel geometry and channel slope are used to examine relations between reach‐average shear stress and bed sediment grain size. Slopes at the study sites range from 0·0003 to 0·07; bankfull depths range from 0·2 to 5 m and bankfull widths range from 2 to 200 m. The data show that there is much less variation in the median grain size of the substrate, D50s, than there is in the median grain size of the surface, D50; the ratio of D50 to D50s thus decreases from about four in headwater reaches with high shear stress to less than two in downstream reaches with low shear stress. Similar trends are observed in an independent data set obtained from measurements in gravel‐bed streams in Idaho. A conceptual quantitative model is developed on the basis of these observations to track differences in bed load transport through an idealized stream system. The results of the transport model suggest that downstream trends in total bed load flux may vary appreciably, depending on the assumed relation between surface and substrate grain sizes. Copyright © 2007 John Wiley & Sons, Ltd.
Measuring river velocities using GPS River Flow Tracers (GRiFTers)
Authors: Stockdale R. J. , McLelland S. J. , Middleton R. , Coulthard T. J. 
Published: October 2007

AbstractExisting methods of measuring flow velocities in natural rivers are largely based on series of point measurements. Acquisition of these data can be time consuming and difficult, especially in high flow conditions. This paper introduces the use of GPS drifters (termed GRiFTers) to measure surface flow velocities in a 400 m reach of the River Swale, UK. Over 10 000 measurements were made in a 3 hour period and aggregated over a 2 m grid to generate a genuine distributed representation of flow across the reach. The technique shows great promise to provide new insights into flow patterns over long reaches of rivers, over a range of flow conditions, and may also provide valuable data for numerical model validation. Copyright © 2007 John Wiley & Sons, Ltd.
Developing an intervention for depressed, chronically medically ill elders: a model from COPD
Authors: Alexopoulos George S. , Raue Patrick J. , Sirey Jo Anne , Arean Patricia A. 
Published: October 2007

AbstractBackgroundGeriatric depression preferentially afflicts individuals with chronic medical illnesses. Disability, hopelessness, lack of acceptance of antidepressant treatment, and limited problem‐solving skills contribute to poor treatment adherence, compromised outcomes, and chronically experienced adversity.MethodsThis paper uses depression comorbid with chronic obstructive pulmonary disease (COPD) as a model entity to develop an approach for integrating treatment components essential for improving treatment adherence and outcomes.ResultsThe behavioral inertia of depression and its coexisting cognitive problems reduce adherence to the sustained and complex demands of the COPD rehabilitation regimen and antidepressant treatment. An intervention identifying reasons for poor treatment adherence and offering direct instructions for addressing them can be combined with problem‐solving therapy to target treatment adherence, depressive symptoms, and disability.ConclusionsAn intervention focusing on treatment adherence and problem‐solving skills development may serve as the platform for administering specific treatments to address the interacting problems of depressed medically ill patients. Copyright © 2007 John Wiley & Sons, Ltd.
Functional connectivity estimation in fMRI data: Influence of preprocessing and time course selection
Authors: Gavrilescu Maria , Stuart Geoffrey W. , Rossell Susan , Henshall Katherine , McKay Colette , Sergejew Alex A. , Copolov David , Egan Gary F. 
Published: October 2007

AbstractA number of techniques have been used to provide functional connectivity estimates for a given fMRI data set. In this study we compared two methods: a ‘rest‐like’ method where the functional connectivity was estimated for the whitened residuals after regressing out the task‐induced effects, and a within‐condition method where the functional connectivity was estimated separately for each experimental condition. In both cases four pre‐processing strategies were used: 1) time courses extracted from standard pre‐processed data (standard); 2) adjusted time courses extracted using the volume of interest routines in SPM2 from standard pre‐processed data (spm); 3) time courses extracted from ICA denoised data (standard denoised); and 4) adjusted time courses extracted from ICA denoised data (spm denoised). The temporal correlation between time series extracted from two cortical regions were statistically compared with the temporal correlation between a time series extracted from a cortical region and a time series extracted form a region placed in CSF. Since the later correlation is due to physiological noise and other artifacts, we used this comparison to investigate whether rest‐like and task modulated connectivity could be estimated from the same data set. The pre‐processing strategy had a significant effect on the connectivity estimates with the standard time courses providing larger connectivity values than the spm time courses for both estimation methods. The CSF comparison indicated that for our data set only rest‐like connectivity could be estimated. The rest‐like connectivity values were similar with connectivity estimated from resting state data. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.
Latent volumetric structure of the human brain: Exploratory factor analysis and structural equation modeling of gray matter volumes in healthy children and adults
Authors: Colibazzi Tiziano , Zhu Hongtu , Bansal Ravi , Schultz Robert T. , Wang Zhishun , Peterson Bradley S. 
Published: October 2007

AbstractPrevious studies have investigated patterns of volumetric covariance (i.e. intercorrelation) among brain regions. Methodological issues, however, have limited the validity and generalizability of findings from these prior studies. Additionally, patterns of volumetric covariance have often been assumed to reflect the presence of structural networks, but this assumption has never been tested formally. We identified patterns of volumetric covariance, correlated these patterns with behavioral measures, and tested the hypothesis that the observed patterns of covariance reflect the presence of underlying networks. Specifically, we performed factor analysis on regional brain volumes of 99 healthy children and adults, and we correlated factor scores with scores on the Stroop Word‐Color Interference Test. We identified four latent volumetric systems in each hemisphere: dorsal cortical, limbic, posterior, and basal ganglia. The positive correlation of the right posterior system with Stroop scores suggested that larger latent volumes are detrimental to inhibitory control. We also applied Structural Equation Modeling (SEM) to our dataset (n = 107) to test whether a model based on the anatomical pathways within cortico‐striatal‐thalamic‐cortical (CSTC) circuits accounts for the covariances observed in our sample. The degree to which SEM predicted volumetric covariance in the CSTC circuit depended on whether we controlled for age and whole brain volume in the analyses. Removing the effects of age worsened the fit of the model, pointing to a possible developmental component in establishing connections within CSTC circuits. These modeling techniques may prove useful in the future for the study of structural networks in disease populations. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.
Health and labour force participation of older people in Europe: What do objective health indicators add to the analysis?
Authors: Kalwij Adriaan , Vermeulen Frederic 
Published: October 2007

AbstractThis paper studies labour force participation of older individuals in 11 European countries. The data are drawn from the new Survey of Health, Ageing and Retirement in Europe (SHARE). We examine the value added of objective health indicators in relation to potentially endogenous self‐reported health. We approach the endogeneity of self‐reported health as an omitted variables problem. In line with the literature on the reliability of self‐reported health ambiguous results are obtained. In some countries self‐reported health does a fairly good job and controlling for objective health indicators does not add much to the analysis. In other countries, however, the results show that objective health indicators add significantly to the analysis and that self‐reported health is endogenous due to omitted objective health indicators. These latter results illustrate the multi‐dimensional nature of health and the need to control for objective health indicators when analysing the relation between health status and labour force participation. This makes an instrumental variables approach to deal with the endogeneity of self‐reported health less appropriate. Copyright © 2007 John Wiley & Sons, Ltd.
Explaining trends in concentration of healthcare commissioning in the English NHS
Authors: Dusheiko Mark , Goddard Maria , Gravelle Hugh , Jacobs Rowena 
Published: October 2007

AbstractIn recent years there have been marked changes in organisational structures and budgetary arrangements in the English National Health Service, potentially altering the relationships between purchasers (primary care organisations (PCOs) and general practices) and hospitals. We show that elective admissions from PCOs and practices became significantly more concentrated across hospitals between 1997/98 and 2002/03. There was a reduction in the average number of hospitals used by PCOs (16.7–14.2), an increase in the average share of admissions accounted for by the main hospital (49–69%), and an increase in the average Herfindahl index (0.35–0.55). About half the increase in concentration arose from the increase in the number of purchasing organisations as 100 health authorities were replaced by 303 primary care trusts. Most of the remainder was probably due to hospital mergers. Fundholding general practices that held budgets for elective admissions had less concentrated admission patterns than non‐fundholders whose admissions were paid for by their PCO. Around 1/10th of the increase in concentration at practice level was due to the abolition of fundholding in April 1999. Our results have implications for the effects of the recent reintroduction of fundholding and the halving of the number of PCOs. Copyright © 2007 John Wiley & Sons, Ltd.
Attribute substitution in early enrollment decisions into Medicare prescription drug plans
Authors: Frakt Austin B. , Pizer Steven D. 
Published: October 2007

AbstractStand‐alone outpatient prescription drug plans (PDPs), introduced in January 2006, have become the most popular source for coverage of outpatient prescription drugs under Medicare relative to other available Medicare plan types (e.g. Medicare Advantage drug plans). Using county‐level enrollment figures from the Centers for Medicare & Medicaid Services linked to other public sources, we study attribute substitution in beneficiary decision‐making with respect to PDP enrollment. To do so, we relate county‐level PDP market share to county‐level political support for the administration implementing the new benefit (the Bush Administration), controlling for socio‐demographic and market characteristics. We find statistically significant evidence that greater support for the Bush administration is associated with increased PDP market share. Copyright © 2007 John Wiley & Sons, Ltd.
Long‐term precipitation and slide activity in south‐eastern Norway, autumn 2000
Authors: Jaedicke Christian , Kleven Arne 
Published: October 2007

AbstractIn autumn 2000 high amounts of precipitation caused a large number of landslides in south‐eastern Norway. The precipitation reached more than 400% of the normal monthly values in November. In addition to the precipitation, groundwater monitoring showed unusual high levels. High air temperatures in the mountains caused the precipitation to fall as rain instead of snow, causing additional runoff in the catchments. In this paper, 90 landslides are presented that were studied and evaluated by the Norwegian Geotechnical Institute (NGI) in the counties effected by the slide activity. The landslide database serves as start point for an analysis of the connection between slide activity and precipitation. The analysis shows a high variability of the observed precipitation just a few days before the slides. This variability decreases significantly around 50 days prior to the slides when the results stabilize at about 400% of normal precipitation in a 50‐day period. Comparison of these results to long time observations gives an estimate of return periods for the precipitation events. The 53 days accumulated precipitation has the highest return period of 132 years. This suggests that the high landslide activity in autumn 2000 in south‐eastern Norway was caused by a long‐term infiltration of large amounts of precipitation rather than high rainfall intensities during a short period. Copyright © 2007 John Wiley & Sons, Ltd.
Phosphoinositide 3‐kinase/Akt pathway plays an important role in chemoresistance of gastric cancer cells against etoposide and doxorubicin induced cell death
Authors: Yu Hong‐Gang , Ai Yao‐Wei , Yu Liang‐Liang , Zhou Xiao‐Dong , Liu Jin , Li Jun‐Hua , Xu Xi‐Ming , Liu Song , Chen Jing , Liu Fen , Qi Yuan‐Ling , Deng Quanjun , Cao Jun , Liu Shi‐Quan , Luo He‐Sheng , Yu Jie‐Ping 
Published: October 2007

AbstractThe major obstacle to successful treatment of gastric cancer is chemotherapy resistance. Our study was designed to investigate the role of phosphoinositide 3‐kinase (PI3K)/Akt pathway in the development of chemoresistance in gastric cancer. In the present study, elevated Akt expression and Akt phosphorylation (Ser 473), as well as decreased PTEN expression were observed in 28 cases of gastric cancer tissues. Etoposide and doxorubicin stimulated Akt and PI3K activities in 2 gastric cancer cell lines (BGC‐823 and SGC‐7901), and the activities were concentration and time‐dependent. Up‐regulation of PTEN expression in BGC‐823 cells by PEAK8‐PTEN transient transfection obviously decreased the basal and anticancer drugs induced Akt activities, then sensitized BGC‐823 cells to etoposide and doxorubicin. Pretreatment of BGC‐823 and SGC‐7901 cells with wortmannin, a PI3K inhibitor, attenuated cells's resistance to etoposide and doxorubicin. In addition, pretreatment of wortmannin blocked etoposide and doxorubicin induced IkappaB‐α degradation, NFkappaB activation, phosphorylation of Akt, MDM‐2 and forkhead transcription factors. Wortmannin pretreatment also promoted the accumulation of p27/Kip, but inhibited the Mcl‐1 expression. Furthermore, wortmannin promoted etoposide and doxorubicin induced caspase‐3, caspase‐9 activation and poly ADP‐ribose polymerase cleavage. Taken together, the observations indicate the PI3K/Akt pathway plays an important role in the chemoresistance of gastric cancer cells. A new strategy for combined chemotherapy of gastric cancer should be designed to more specifically block PI3K/Akt pathway and then decrease the amount of resistant cells. © 2007 Wiley‐Liss, Inc.
Diagnostic performance of stereotactic large core needle biopsy for nonpalpable breast lesions in routine clinical practice
Authors: Peters Nicky , Hoorntje Lidewij , Mali Willem , Borel Rinkes Inne , Peeters Petra 
Published: October 2007

AbstractThe COBRA (COre Biopsy after RAdiological localization) study showed that in a controlled study setting, stereotactic large core needle biopsy (LCNB) is as reliable for diagnosing nonpalpable breast lesions as open surgical biopsy. In the present study, we evaluated the diagnostic performance of stereotactic LCNB in routine clinical practice. Between February 2000 and June 2002, data on all patients (n = 955) with nonpalpable breast lesions referred for LCNB were collected. High risk underestimate rate, ductal carcinoma in situ (DCIS) underestimate rate and sensitivity rate after 2 years were calculated. The usefulness of the COBRA guidelines in clinical practice was determined. Nine hundred five successful biopsies were performed in 874 patients. Of the high‐risk lesions, 27% were found to be carcinomas on open biopsy, which is comparable to the results of the COBRA study (23%). The DCIS underestimate rate (28%) was higher than found in the COBRA study (17%). No carcinomas were missed after a follow‐up period of 2 years. Ninety‐six percent of patients were treated according to the COBRA guidelines. The diagnostic performance of stereotactic LCNB in patients with nonpalpable breast lesions seems to be comparable in a controlled study setting and routine clinical practice. © 2007 Wiley‐Liss, Inc.
Protein kinase CK2 is a key activator of histone deacetylase in hypoxia‐associated tumors
Authors: Pluemsampant Sireerat , Safronova Olga S. , Nakahama Ken‐ichi , Morita Ikuo 
Published: October 2007

AbstractIncreasing evidence points to a link between histone deacetylases (HDACs) and tumorigenesis. Although several HDAC inhibitors have been tested in clinical trials for cancer therapies, the mechanisms of HDAC activation in tumors remain unknown. In this study, we investigated the pathway of HDAC activation in the context of hypoxia and inflammation, common features of solid tumors. In HeLa cells, hypoxia was a more potent activator of HDAC than IL‐1β. As HDAC protein expression did not change during treatment, we hypothesized that hypoxia regulated HDAC activity through post‐translational modification. We observed that hypoxia induced HDAC1 and HDAC2 protein phosphorylation both in the presence and absence of IL‐1β. Using TBB, an inhibitor of protein kinase CK2, we showed that CK2 was required for hypoxia‐induced HDAC activation. We also observed that CK2 activity was induced by hypoxia but not by IL‐1β alone. While CK2β subunits were retained in the cytoplasm upon hypoxic treatment, CK2α and CK2α′ subunits were shuttled to the nucleus, where HDAC1 and HDAC2 are predominantly localized. Knockdown of catalytic and regulatory subunits of CK2 revealed that formation of heterotetramic complex was not required for HDAC phosphorylation. von Hippel‐Lindau protein (pVHL) inactivation and hypoxia inducible factor‐1α (HIF‐1α) activation are associated with tumor growth and vasculogenesis. Use of Apicidin (an HDAC inhibitor) and TBB revealed that CK2‐dependent HDAC activation contributed to pVHL downregulation and HIF‐1α stabilization under hypoxia. Our findings that CK2 may be a key mediator for HDAC activation under hypoxia support the future application of CK2 inhibitors in cancer therapy. © 2007 Wiley‐Liss, Inc.