bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Access to L‐Azetidine‐2‐carboxylic Acid
Authors: Bouazaoui M'barek , Martinez Jean , Cavelier Florine 
Published: April 2009

AbstractA straightforward synthesis of L‐azetidine‐2‐carboxylic acid is described, leading to both orthogonally protected versions or totally deprotected L‐Aze. The starting material is a commercially available aspartic acid derivative, whose chirality is conserved. The (2‐trimethylsilyl)ethanesulfonyl protecting group (SES) acts as a leaving group on the hydroxy function and serves as an activator for the amine function, which is the key‐step of the reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Dihydroazulene Photoswitches: The First Synthetic Protocol for Functionalizing the Seven‐Membered Ring
Authors: Petersen Michael Åxman , Broman Søren Lindbæk , Kadziola Anders , Kilså Kristine , Nielsen Mogens Brøndsted 
Published: April 2009

AbstractThe first synthetic protocol for functionalizing the dihydroazulene (DHA) photoswitch in its seven‐membered ring has been developed. This protocol is based on regioselective bromination, followed by regioselective elimination of HBr, and finally a palladium‐catalyzed cross‐coupling reaction with a terminal alkyne. The position of functionalization (C‐7) was confirmed by X‐ray crystal structure analysis. Light‐induced ring opening of this compound to its vinylheptafulvene (VHF) isomer followed by thermal ring closure provides a mixture of two DHA regioisomers in a ratio that depends on the wavelength of irradiation and solvent polarity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Role of a rheophyte in bench development on a sand‐bed river in southeast Australia
Authors: Erskine Wayne , Chalmers Anita , Keene Annabelle , Cheetham Michael , Bush Richard 
Published: April 2009

AbstractCasuarina cunninghamiana Miq. is an important rheophytic tree in New South Wales, Australia because it is fast growing and can tolerate flood disturbance. Widden Brook is an active sand‐bed stream that has widened substantially since initial European settlement in the early 1800s and is characterized by high flood variability and multi‐decadal periods of alternating high and low flood frequency, called flood‐ and drought‐dominated regimes. Channel contraction by bench formation is currently occurring. Conversion of coarse‐grained point bars to benches is an important process of channel contraction. When point bars grow to a height where suspended sediment is first deposited to thicknesses of at least 50 mm by sub‐bankfull floods, rapid establishment of C. cunninghamiana occurs. As the trees grow they partially block bankside flows, thereby locally reducing flow velocity and inducing further deposition on the benches. Such synergistic relationships between bar height and inundation, fine‐grained sediment deposition, tree establishment and the development of a bankside low current velocity zone are fundamental for bench development. Size‐class frequency data demonstrate that C. cunninghamiana on the benches consists of pure even‐aged stands with most trees clustering near the average diameter. Two benches have similar size class frequency distributions but a third has significantly smaller trees. Recruitment on benches is episodic, may occur in areas open to grazing and is dependent on favourable conditions that allow tree survival. These favourable conditions include high seed availability, low levels of competition, deposition of fine sediments and adequate moisture for tree growth. Although C. cunninghamiana germinates on bars, seedlings are eliminated by prolonged inundation or flood scour and do not reach maturity. Recurring catastrophic floods or a sequence of large floods in rapid succession episodically destroy benches by substantial channel widening and initiate a new phase of bar and bench development. A conceptual model of the conversion of point bars to benches by thick mud deposition and C. cunninghamiana recruitment has been developed for sand‐bed streams draining similar sandstone catchments. Copyright © 2009 John Wiley & Sons, Ltd.
An empirical model of event scale cohesive bank profile evolution
Authors: Pizzuto Jim 
Published: April 2009

AbstractThe highly stochastic nature of riverbank erosion has driven the need for spatially explicit empirical models. Detailed bank profile surveys along a meander bend of the Brandywine Creek in Pennsylvania, USA, before and after 28 high flow events over a 2·5 year period are used to develop an empirical model of cohesive bank profile erosion. Two hundred and thirty‐six bank erosion observations are classified as hydraulic erosion or subaerial erosion. Threshold conditions required to initiate bank erosion cannot be defined based on field measurements. Using the near‐bank velocity and the number of freeze–thaw cycles as predictors, regression equations are derived for hydraulic erosion that specify the length, thickness, and location on the bank face of eroded blocks. An empirical discriminant function defines the critical geometry of overhang failures, and the volumes removed by overhang failures are computed using another regression equation. All the regression equations are significant, but have low correlation coefficients, suggesting that cohesive bank erosion has a strong stochastic component. Individual events typically remove small masses of soil (average volume 0·084 m3/m) a few centimeters thick (median = 0·057 m) and a few decimeters in length (median = 0·50 m) from the lower third of the bank. Hydraulic erosion is responsible for 87% of all erosion. When applied to three survey sites not used in its development, the profile model predicts the total volume of erosion with errors of 23%, 5% and 1%. Twenty‐four percent of computed erosion volumes for single events are within 50% of observed volumes at these three sites. Extending the approach to decadal timescales and to entire bends will require three‐dimensional observations of bank failure, and spatially and temporally explicit methods to account for the influence of individual large trees on bank failures and near‐bank hydraulic processes. Copyright © 2009 John Wiley & Sons, Ltd.
Functional status of men with the fragile X premutation, with and without the tremor/ataxia syndrome (FXTAS)
Authors: Brega Angela G. , Reynolds Ann , Bennett Rachael E. , Leehey Maureen A. , Bounds Lanee S. , Cogswell Jennifer B. , Hagerman Randi J. , Hagerman Paul J. , Grigsby Jim 
Published: April 2009

AbstractBackgroundFragile X‐associated tremor/ataxia syndrome (FXTAS), which occurs in some premutation carriers of the fragile X mental retardation 1 (FMR1) gene, is a neurodegenerative disorder characterized by action tremor, gait ataxia, and impaired executive cognitive functioning.ObjectiveTo evaluate the nature and severity of functional limitations among male carriers of the fragile X premutation, both with and without FXTAS.MethodsForty‐two subjects with FXTAS and 24 asymptomatic premutation carriers were compared to 32 control subjects on measures of physical functioning, activities of daily living (ADLs; e.g. eating, bathing), and instrumental activities of daily living (IADLs; e.g. shopping, managing medications). Ordinary least squares regression, controlling for age, education, medical comorbidity, and pain, was used to examine group differences in physical and functional performance.ResultsMen with FXTAS performed significantly worse than control subjects on all dependent measures, showing greater limitations in physical functioning, as well as ADL and IADL performance (p < 0.05). Subsequent analyses suggested that physical and functional impairments among men with FXTAS result largely from deficits in motor and executive functioning and that CGG repeat length is associated with functional impairment. Asymptomatic carriers of the fragile X premutation performed similarly to control subjects on all measures.ConclusionsThis study provides the first comprehensive evaluation of functional status among male premutation carriers. Although carriers without FXTAS performed similarly to control subjects, men with FXTAS showed evidence of significant physical and functional impairment, which appears to result largely from motor and executive deficits characteristic of the syndrome. Copyright © 2009 John Wiley & Sons, Ltd.
The effect of newer drugs on health spending: do they really increase the costs?
Authors: Ci̇van Abdülkadi̇r , Köksal Bülent 
Published: April 2009

AbstractWe analyze the influence of technological progress on pharmaceuticals on rising health expenditures using US State level panel data. Improvements in medical technology are believed to be partly responsible for rapidly rising health expenditures. Even if the technological progress in medicine improves health outcomes and life quality, it can also increase the expenditure on health care. Our findings suggest that newer drugs increase the spending on prescription drugs since they are usually more expensive than their predecessors. However, they lower the demand for other types of medical services, which causes the total spending to decline. We estimate that a 1‐year decrease in the average age of prescribed drugs causes per capita health expenditures to decrease by $45.43. The biggest decline occurs in spending on hospital care due to newer drugs. Copyright © 2009 John Wiley & Sons, Ltd.
A single‐trace dual‐process model of episodic memory: A novel computational account of familiarity and recollection
Authors: Greve Andrea , Donaldson David I. , van Rossum Mark C.W. 
Published: April 2009

AbstractDual‐process theories of episodic memory state that retrieval is contingent on two independent processes: familiarity (providing a sense of oldness) and recollection (recovering events and their context). A variety of studies have reported distinct neural signatures for familiarity and recollection, supporting dual‐process theory. One outstanding question is whether these signatures reflect the activation of distinct memory traces or the operation of different retrieval mechanisms on a single memory trace. We present a computational model that uses a single neuronal network to store memory traces, but two distinct and independent retrieval processes access the memory. The model is capable of performing familiarity and recollection‐based discrimination between old and new patterns, demonstrating that dual‐process models need not to rely on multiple independent memory traces, but can use a single trace. Importantly, our putative familiarity and recollection processes exhibit distinct characteristics analogous to those found in empirical data; they diverge in capacity and sensitivity to sparse and correlated patterns, exhibit distinct ROC curves, and account for performance on both item and associative recognition tests. The demonstration that a single‐trace, dual‐process model can account for a range of empirical findings highlights the importance of distinguishing between neuronal processes and the neuronal representations on which they operate. © 2009 Wiley‐Liss, Inc.
Clinical application of measurement of hippocampal atrophy in degenerative dementias
Authors: Barnes Josephine , Ourselin Sebastien , Fox Nick C. 
Published: April 2009

AbstractHippocampal atrophy is a characteristic and early feature of Alzheimer's disease. Volumetry of the hippocampus using T1‐weighted magnetic resonance imaging (MRI) has been used not only to assess hippocampal involvement in different neurodegenerative diseases as a potential diagnostic biomarker, but also to understand the natural history of diseases, and to track changes in volume over time. Assessing change in structure circumvents issues surrounding interindividual variability and allows assessment of disease progression. Disease‐modifying effects of putative therapies are important to assess in clinical trials and are difficult using clinical scales. As a result, there is increasing use of serial MRI in trials to detect potential slowing of atrophy rates as an outcome measure. Automated and yet reliable methods of quantifying such change in the hippocampus would therefore be very valuable. Algorithms capable of measuring such changes automatically have been developed and may be applicable to predict decline to a diagnosis of dementia in the future. This article details the progress in using MRI to understand hippocampal changes in the degenerative dementias and also describes attempts to automate hippocampal segmentation in these diseases. © 2009 Wiley‐Liss, Inc.
Forecasting realized volatility: a Bayesian model‐averaging approach
Authors: Liu Chun , Maheu John M. 
Published: April 2009

AbstractHow to measure and model volatility is an important issue in finance. Recent research uses high‐frequency intraday data to constructex postmeasures of daily volatility. This paper uses a Bayesian model‐averaging approach to forecast realized volatility. Candidate models include autoregressive and heterogeneous autoregressive specifications based on the logarithm of realized volatility, realized power variation, realized bipower variation, a jump and an asymmetric term. Applied to equity and exchange rate volatility over several forecast horizons, Bayesian model averaging provides very competitive density forecasts and modest improvements in point forecasts compared to benchmark models. We discuss the reasons for this, including the importance of using realized power variation as a predictor. Bayesian model averaging provides further improvements to density forecasts when we move away from linear models and average over specifications that allow for GARCH effects in the innovations to log‐volatility. Copyright © 2009 John Wiley & Sons, Ltd.
Aggregation is not the solution: the PPP puzzle strikes back
Authors: Gadea M. Dolores , Mayoral Laura 
Published: April 2009

AbstractRecently, Imbs, Mumtaz, Ravn and Rey (2005, hereinafter IMRR) have argued that much of the purchasing power parity (PPP) puzzle is due to upwardly biased estimates of persistence. According to them, the source of the bias is the existence of heterogeneous price adjustment dynamics at the sectoral level that established time series or panel data methods fail to control for. This paper re‐examines this claim in two steps. Firstly, we demonstrate that IMRR's measures of sectoral persistence are systematically downwardly biased because they are based on an inaccurate definition of the ‘average’ impulse response function (IRF). We then show that standard estimates of shock persistence are recovered after this bias is corrected. Secondly, building on the results in Mayoral (2008), which prove that aggregate and micro models induce the same shock persistence behavior, we show that estimates based on aggregate and sectoral exchange rates are, in fact, highly consistent. Thus, aggregation is not the solution to the PPP puzzle. Copyright © 2009 John Wiley & Sons, Ltd.
Wear and hardness of different core build‐up materials
Authors: Schmage Petra , Nergiz Ibrahim , Sito Fekry , Platzer Ursula , Rosentritt Martin 
Published: April 2009

AbstractBefore crown preparation, teeth with extensive coronal destructions are built up with core materials. Sometimes, these build ups are exposed to the oral environment without the protection of crowns. Therefore, this in vitro investigation was aimed at evaluating the wear, surface roughness, Vickers hardness, and surface structure of 10 core composites, two glass ionomer cements (GICs), and four posterior restoration composites. The three‐body wear was tested after water storage and 2,00,000 cycles. We measured both surface roughness and Vickers hardness (DIN 50133) and evaluated the surface structures by scanning electron microscopy. Results were statistically analyzed by use of the Mann‐Whitney U test (α = 0.05). Lowest wear was found for the restorative composites (20 μm Grandio; others about 40 μm). A comparison of the composites Build‐It, Chroma Core, Rebilda LC, and Rebilda DC to Quixfil showed similar wear values for each material (43–50 μm). Wear values of GICs and all others core composites ranged between 58 and 75 μm. Only Ti‐Core showed significantly higher wear than all other materials (p < 0.05). All core materials except Ti‐Core (35 HV) showed Vickers hardness values between 42 and 61 HV. Most core composites, particularly Build‐It, Multicore Flow, Rebilda LC, Ecusit, and Tetric Evo Ceram, showed more homogenous surface structures compared to GICs and restorative composites. Therefore, wear values of core build‐up materials not only differed widely but were higher than those of conventional restorative materials; yet, core build‐up materials showed advantageous surface structures. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009
Membrane autopsy to investigate CaCO3 scale formation in pilot‐scale, submerged membrane bioreactor treating calcium‐rich wastewater
Authors: Lee Mooseok , Kim Jeonghwan 
Published: April 2009

AbstractBACKGROUND: Membrane scaling is an area of research interest because it can deteriorate membrane performance. The extent to which membrane scaling is produced varies depending upon the concentration of scale‐forming species such as calcium on the membrane surface. Bench‐scale tests have been conducted to better understand membrane scaling in submerged membrane reactors (MBR). However, relatively few studies of membrane scaling in pilot‐scale, submerged MBR have been reported. The objective of this study was to perform membrane autopsy work to analyze membrane scaling in a submerged MBR treating calcium‐rich wastewater.RESULTS: Membrane autopsy work provided evidence that deposition of calcium carbonate (CaCO3) scale occurred on the membrane surface at the completion of pilot‐scale, submerged MBR operation. The CaCO3 scaling resulted in significant external fouling on the surface of the membrane. The membrane scaling increased the rejection of calcium with MF membranes. However, the level of CaCO3 scaling as internal fouling (in the pores) was almost negligible. This autopsy work also showed that aeration did not play a major role in controlling CaCO3 scaling at the membrane surface in a submerged MBR. Chemical cleaning using citric acid solution efficiently removed CaCO3 scale from the membrane. Combining citric acid with sodium hypochlorite pretreatment provided synergistic effects, further reducing CaCO3 scale formation.CONCLUSION: The carbonate salt of calcium leads to precipitation resulting in surface fouling of membranes, and this cannot be removed physically by aeration in a submerged MBR treating calcium‐rich wastewater. It is necessary to combine properly‐selected cleaning strategies with submerged MBR treating wastewater containing a high potential for inorganic chemical precipitates. Copyright © 2009 Society of Chemical Industry
Production of vanillin from wheat bran hydrolyzates via microbial bioconversion
Authors: Di Gioia Diana , Sciubba Luigi , Ruzzi Maurizio , Setti Leonardo , Fava Fabio 
Published: April 2009

AbstractBACKGROUND: Wheat bran contains a large amount of ferulic acid, which can be released through enzymatic hydrolysis and bioconverted into vanillin. A previous study has shown that ferulic acid purification from bran carbohydrates with the Amberlite® IRA 95 resin allowed an increased vanillin molar yield. In this work, alternative ferulic acid recovery methods were proposed and the possibility of exploiting the residual carbohydrate‐rich water phase was explored.RESULTS: Ferulic acid was recovered from crude wheat bran hydrolyzate by: (i) a hydrophobic sorbent cartridge (ISOLUTE ENV+®): (ii) ethyl acetate extraction; and (iii) the resin previously employed. The highest recovery percentage (95%) was obtained with ISOLUTE ENV+®, which also allowed an interesting vanillin molar yield from ferulic acid bioconversion (75% from 0.5 mmol L−1 ferulic acid). The residual water phase was a good growth substrate for the microorganism operating the bioconversion. Cells grown on this matrix could efficiently bioconvert the recovered ferulic acid to vanillinCONCLUSION: The possibility of efficiently recovering ferulic acid from wheat bran hydrolyzates, bioconverting it into vanillin, and valorizing the sugar‐rich exhausted water fraction was demonstrated in this work. The approach allowed the production of a value‐added fine‐chemical from a food‐industry by‐product. Copyright © 2009 Society of Chemical Industry
Effects of current density and electrode material on the dewaterability of the thickened activated sludge by electro‐flotation
Authors: Choi Young Gyun , Kim Seong Hong , Kim Hee Jun , Kim Yun Jung , Chung Tai Hak 
Published: April 2009

AbstractBACKGROUND: Electro‐flotation (EF) could improve thickening and subsequent dewatering characteristics of activated sludge although the settling characteristics of the sludge were very poor. The objectives of this study were to evaluate the performance of EF in the thickening and dewatering of activated sludge and the effects of current density and electrode material on the dewaterability of the sludge.RESULTS: The specific resistance to filtration (SRF) of the sludges thickened by EF was much lower than that by gravity sedimentation. The SRF of the thickened sludge decreased exponentially with increase of gas generation rate of the EF system. Gas generation rate could be controlled by varying the current density of the electrode. Degassing of the microbubbles by moderate mixing of the thickened sludge layer deteriorated the dewaterability of the sludge. Therefore, it is obvious that the gas bubbles entrapped in the thickened sludge play a key role in the observed dewaterability improvement. The effect of electrode material on the thickening and dewatering efficiency was trivial compared with the effect of current density of the electrode.CONCLUSION: The EF system was quite promising as an alternative to gravity sedimentation for thickening of activated sludge and the dewaterability was also improved by microbubbles generated in the system. Copyright © 2009 Society of Chemical Industry
γH2AX marks the main events of the spermatogenic process
Authors: Blanco‐Rodríguez Josefa 
Published: April 2009

AbstractRecent findings reveal that chromatin reorganization requires formation and repair of DNA double strand breaks (DSBs). Therefore, dynamic changes in chromatin structure taking place along the mitotic and the meiotic processes should be accompanied by histone H2AX phosphorylation and formation of γH2AX, a prominent event occurring at DSB sites. Accordingly, γH2AX has been detected at multiple developmental steps in adult germ cells. Nevertheless, no comprehensive study focusing on the main biological events occurring in the seminiferous epithelium has been carried out in mammals. Here I analyze H2AX phosphorylation in immunostained testis sections comparing PAS/cresyl violet counterstained, noncounterstained, and immuno‐fluorescence preparations and show several waves of H2AX phosphorylation/dephosphorylation coupled to various developmental phases of spermatogonia and spermatocytes as well as to spermatid differentiation. The combined detection of DNA replication or free 3′‐OH DNA ends highlight the possible significance of γH2AX at these locations. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.