bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contrasting weathering and climate regimes in forested and cleared sandstone temples of the Angkor region
Authors: André Marie‐Françoise , Voldoire Olivier , Roussel Erwan , Vautier Franck , Phalip Bruno , Peou Hang 
Published: November 2011

ABSTRACTComparative assessment of stone weathering intensities and bioclimatic conditions was conducted at four temples located in cleared and forested sites of the Angkor Park, based on similar protocols. Four thousand sculpted lotus petals carved in the same grey sandstone were categorized by using two customized scales of weathering intensity, and climate monitoring was conducted from December 2008 to November 2009. Whereas 70% of the sandstone lotus petals are almost completely destroyed by mechanical weathering in cleared areas, 74% of petals located in forested environments appear to be totally free of mechanical weathering and are only affected by superficial biochemical weathering. Ambient conditions are also contrasting, with the magnitude of the diurnal surface temperature and relative humidity ranges being three times higher at cleared sites than in wooded areas. As wetting–drying cycles are the driving force of sandstone decay at Angkor, causal links are suggested between weathering and climate regimes. In wooded areas, the microclimate is buffered by the forest and the associated lithobionts, which maintain constant humidity levels, reduce thermal stresses at the stone surface and induce a slow biochemical weathering regime. In cleared areas, direct exposure to sunshine and monsoon rains induces pronounced wetting–drying cycles conducive to swelling–shrinking movements and other potential processes, provoking the rapid mechanical decay of the sandstone. Even if local damage can be caused by tree roots, the forest cover and the associated lithobionts obviously play an overall protective role. Additionally, microtopographical factors related to architectural designs and post‐building events probably explain intra‐site and between site minor differences in the amount of sandstone decay, by influencing key factors such as the water residence time at the stone surface. Last, the contrasting weathering regimes in forested and cleared sites are but a trend, for besides overwhelming mechanical weathering, chemical weathering is also operative at cleared sites, as indicated by salt efflorescences and ferric oxidation. Copyright © 2012 John Wiley & Sons, Ltd.
How natural are Alpine mountain rivers? Evidence from the Italian Alps
Authors: Comiti Francesco 
Published: November 2011

ABSTRACTHistorical, human‐induced channel adjustments in lowland gravel‐bed rivers have been documented in several geographical contexts worldwide. In particular, it is now widely accepted that the vast majority of European rivers are far from any natural, reference state prior to anthropic disturbances, and a ‘complete’ restoration is hardly achievable. However, few investigations have addressed changes that have occurred in mountain rivers of the Alps, and these channels are commonly reckoned quite ‘natural’ by society. This paper intends to describe how human pressure on Italian Alpine basins has been quite relevant for several centuries – in terms of land‐use variations, in‐channel structures, timber transport (splash damming) and riparian vegetation management – such that nowadays ‘reference conditions’ cannot be found even in small mountain creeks. In addition, recent natural climatic variations (e.g. the Little Ice Age) are superimposed on human disturbances, thus defying the definition of any ‘equilibrium’ morphological conditions even under ‘human‐free’ states. A summary of published as well as unpublished works on historical channel adjustments in rivers of the Italian Alps is presented in order to document the impacts deriving from human pressure at different basin scales and for different river morphologies, from steep confined streams to large unconfined rivers. General options for river management and restoration actions aiming to combine geomorphological functionality and flood hazard mitigation are discussed, in the light of the current European legislative context. Copyright © 2011 John Wiley & Sons, Ltd.
Myocardial edema imaging in acute coronary syndromes
Authors: Walls Michael C. , Verhaert David , Min James K. , Raman Subha V. 
Published: November 2011

AbstractAcute coronary syndromes (ACS) continue to be the most common morbid condition of industrialized nations. The advent of and technical improvements in revascularization and medical therapy have led to a steady decline in mortality rates. However, many patients who suffer unstable angina or myocardial infarction require further testing and risk stratification to guide therapeutic selection and prognosis assignment. Myocardial edema imaging with cardiac magnetic resonance (CMR) affords the ability to define the amount of myocardium at risk, refine estimates of prognosis and provide guidance for therapies with excellent sensitivity compared with standard clinical markers. This review will discuss the rationale for edema imaging, how it is performed using CMR, and potential clinical applications. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.
MR spectroscopy in schizophrenia
Authors: Port John D. , Agarwal Nivedita 
Published: November 2011

AbstractThe purpose of this study is to review the MR spectroscopic literature regarding schizophrenia. However, as there are over 250 primary MRS articles and dozens of MRS review articles on the subject already, this study will take a different approach. First, the clinical features of schizophrenia will be described. The background neuroanatomy and biochemistry relevant to schizophrenia will be reviewed, as many readers of this journal are unlikely to be familiar with these fields. A current model of the abnormal neural circuitry in schizophrenia will be presented, and predictions extrapolated about relevant metabolite changes over time. Finally, the existing MRS literature will be reviewed in the context of our existing anatomical and chemical knowledge, and future MRS research directions will be elaborated. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.
Pressure dependence of phenylperoxy radical formation in the reaction of phenyl radical with molecular oxygen
Authors: Tanaka K. , Ando M. , Sakamoto Y. , Tonokura K. 
Published: November 2011

AbstractPressure dependence of the phenylperoxy radical (C6H5O2) formation in the reaction of phenyl radical (C6H5) with molecular oxygen (O2) has been investigated with the cavity ring‐down method by detecting the C6H5O2at 504 nm. The rate constant of the C6H5+ O2reaction was determined to bek= (1.2 ± 0.1) × 10−11cm3molecule−1s−1by the least‐square analysis of several sets of the C6H5O2rise profiles at 30 Torr and at 296 K. This value is almost identical to those previously obtained at 40 Torr (Yu and Lin,J Am Chem Soc1994, 98, 9571–9576) and 760 Torr (Tonokura et al.,J Phys Chem A2002, 106, 5908–5917), indicating that the rate constant has no pressure dependence in the pressure range of 30–760 Torr. The signal intensity ratio of C6H5O2to C6H5was obtained in the pressure range of 5–120 Torr. Varying the third body carrier gas (N2) had a significant effect on the production of the C6H5O2. To validate thekdetermination by C6H5O2rise detection and determine the branching ratio of C6H5O2in the C6H5+ O2reaction system, theoretical calculations were also performed. The rate constant obtained with Rice–Ramsperger–Kassel–Marcus/master equation calculations is in good agreement with that measured in this experiment. The branching ratio forming C6H5O2obtained by the theoretical calculation also exhibited pressure dependence, which is consistent with the experimental results. The branching ratio increases with increasing pressure and reaches approximately 0.85 at 120 Torr. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 44: 41–50, 2012
A quadratic semidefinite relaxation approach for resource allocation in orthogonal frequency division multiple access
Authors: Adasme Pablo , Lisser Abdel , Soto Ismael 
Published: November 2011

AbstractThis paper proposes two binary quadratically constrained quadratic programs for minimizing power subject to bit rate and subcarrier allocation constraints over wireless orthogonal frequency division multiple access. The first model represents a restricted case in which users are allowed to use only one modulation size in each subcarrier while the second, a more flexible real case in which they can use any size. We propose two semidefinite programming relaxations and compare with the linear programs obtained by applying Fortet linearization method. Numerical results show a total average tightness gain of 42.78 and 97.17% for the first and second quadratic model, respectively. Moreover, we get in average, near optimal lower bounds of 0.5 and 1% for the second model over random and realistic data, respectively. © 2011 Wiley Periodicals, Inc. NETWORKS, 2012
On a stochastic bilevel programming problem
Authors: Kosuch Stefanie , Le Bodic Pierre , Leung Janny , Lisser Abdel 
Published: November 2011

AbstractIn this article, a mixed integer bilevel problem having a probabilistic knapsack constraint in the first level is proposed. The problem formulation is mainly motivated by practical pricing and service provision problems as it can be interpreted as a model for the interaction between a service provider and customers. A discrete probability space is assumed which allows a reformulation of the problem as an equivalent deterministic bilevel problem. The problem is further transformed into a linear bilevel problem, which in turn yields a quadratic optimization problem, namely the global linear complementarity problem. Based on this quadratic problem, a procedure to compute upper bounds on the initial problem by using a Lagrangian relaxation and an iterative linear minmax scheme is proposed. Numerical experiments confirm that the scheme practically converges.© 2011 Wiley Periodicals, Inc. NETWORKS, 2012
Development of innovative voltage control for distribution networks with high photovoltaic penetration
Authors: Bletterie B. , Goršek A. , Fawzy T. , Premm D. , Deprez W. , Truyens F. , Woyte A. , Blazič B. , Uljanič B. 
Published: November 2011

ABSTRACTThe voltage rise caused by photovoltaic (PV) power feed‐in is one of the main network constraints limiting the PV penetration in distribution networks. In this paper, a local voltage control approach for PV inverters based on reactive power management is proposed and investigated into detail. Through a parametric study, various inverter settings are considered and compared for a real medium voltage network with a high PV penetration level and for which a demonstration is planned within the project MetaPV. The purpose of this work is to investigate the suitability of such control concepts to compensate the voltage rise caused by the PV power feed‐in and to provide some guidance on the adjustment of the settings of such control mechanisms. For the assessment of the performance of the control concept with different settings, extensive load flow simulations have been performed for a voltage‐dependent reactive power control (Q(V) characteristics) on the basis of 15‐minute profiles. As a result, voltage time‐series over a period of 1 year are obtained for each case and analysed into details. Apart from the voltage profiles, other features such as network losses and reactive energy import have been quantified because they are also of noticeable importance for network operators. The simulation results show that suitable settings are necessary to maintain the voltage within the prescribed limits. A comparison between the considered cases shows that reactive power control Q(V) with a power factor down to 0.9 is necessary to achieve satisfying results. The use of a dead‐band is recommended for the voltage‐dependent reactive power control in order to limit the losses and reactive energy import. Copyright © 2011 John Wiley & Sons, Ltd.
Nonviral gene delivery using poly‐D/L aspartate‐diethylenetriamine cationic polymers and polyethylene glycol: A two‐step approach
Authors: Mirosevich Janni , Cardoen Gregoire , Burke Brian , Costich Tara , Sill Kevin 
Published: November 2011

AbstractCationic polymers have received much attention as promising nonviral vectors for gene transfer. However, development of polymers with low cell toxicities and high transfection efficiencies continue to be a significant problem and a major hurdle to their success. Poly‐D/L aspartate‐diethylenetriamine poly(D/L Asp‐DET) polymers were synthesized and evaluated as nonviral gene delivery agents. Poly(D/L Asp‐DET) polymers display endosome buffering capacity. The polymers condense plasmid DNA above N:P ratios of 1 and form polyplex particles of ∼50–100 nm, with zeta potentials between neutral and +40 mV. Transmission electron microscopy shows the polyplexes to be uniform in size and shape. Polyplexes maintain the structural integrity of DNA following incubation in nucleases and also show high transfection efficiencies with minimal toxicity in both HCT‐116 and PC‐3 cell culture. However, it is found that these poly(D/L Asp‐DET)/DNA polyplexes immediately aggregate in salt and serum conditions, making them unsuitable for use in vivo. Therefore, the polyplexes were further modified by covalent addition of polyethylene glycol (PEG). Introduction of this second step produces PEG‐polyplexes of uniform size (below 100 nm), with neutral zeta potentials that are also stable in both salt and serum conditions. These results suggest poly(D/L Asp‐DET) cationic polymers as potentially safe and efficient nonviral gene delivery agents. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Ligand‐free Cu(0)‐mediated controlled radical polymerization of methyl methacrylate at ambient temperature
Authors: Wang Wenxiang , Zhang Zhengbiao , Wu Yang , Zhu Jian , Cheng Zhenping , Zhou Nianchen , Zhang Wei , Zhu Xiulin 
Published: November 2011

AbstractFor the first time, ligand‐free Cu(0)‐mediated polymerization of methyl methacrylate (MMA) was realized by the selection of ethyl‐2‐bromo‐2‐phenylacetate as initiator at ambient temperature. The polymerization can reach up to 90% conversion within 5 h with dimethyl sulfoxide (DMSO) as solvent, while keeping manners of the controlled radical polymerization. Extensive investigation of this system revealed that for a well‐controlled Cu(0)‐mediated polymerization of MMA, the initiator should be selected with the structure as alkyl 2‐bromo‐2‐phenylacetate, and the solvent should be DMSO or N,N‐dimethylformamide. The selectivity for solvents indicated a typical single‐electron transfer‐living radical polymerization process. Scanning for other monomers indicated that under equal conditions, the polymerizations of other alkyl (meth)acrylates were uncontrollable. Based on these results, plausible reasons were discussed. The ligand‐free Cu(0)‐mediated polymerization showed its superiority with economical components and needless removal of Cu species from the resultant products. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Characterization of phase separation of polystyrene/poly(vinyl methyl ether) blends using fluorescence
Authors: Kriisa Annika , Park Sung S. , Roth Connie B. 
Published: November 2011

AbstractWe have investigated the fluorescence emission spectra of pyrene and anthracene dyes covalently bonded to polystyrene (PS) upon phase separation from poly(vinyl methyl ether) (PVME). The specific chemical structure of the fluorescent labels is found to affect the measured phase separation temperature TS, with fluorophores covalently attached in closer proximity to the PS backbone identifying phase separation a few degrees earlier. The sharp increase in fluorescence intensity upon phase separation that occurs for all fluorophores with little change in spectral shape is consistent with a mechanism of static fluorescence quenching resulting from the specific interaction with a nearby quenching molecular unit. Based on recent work that has identified a weak hydrogen bond occurring between the aromatic hydrogens of PS and the ether oxygen of PVME, we believe a similar weak hydrogen bond is likely occurring between the PVME oxygen and the aromatic dyes providing a local (few nanometer) sensitivity to phase separation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Stiffness constants prediction of nanocomposites using a periodic 3D‐FEM model
Authors: Cricrì Gabriele , Garofalo Emilia , Naddeo Francesco , Incarnato Loredana 
Published: November 2011

AbstractPredictive models, which enable the prediction of nanocomposite properties from their morphologies and account for polymer orientation, could greatly assist the exploitation of this new class of materials in more diversified and demanding market fields. This article focuses on the prediction of effective elastic properties (Young's moduli) of polymer nanocomposite films (copolyamide‐6/nanoclay) using 3D analytical (based on the Mori‐Tanaka theory) and 3D finite element (FE) models. The analytical model accounts for the orientation of polymer chains induced by drawing. 3D FE model exploits the representative volume element concept and accounts for the nanocomposite morphology as determined from transmission electron microscopy experiments. Model predictions were compared with experimental results obtained for nanocomposite films produced by means a pilot‐scale film blowing equipment and collected at different draw ratios. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Optically induced birefringence and holography in silk
Authors: Cronin‐Golomb Mark , Murphy Amanda R. , Mondia Jessica P. , Kaplan David L. , Omenetto Fiorenzo G. 
Published: November 2011

AbstractIn this study, we demonstrated that thin films of azobenzene‐modified Bombyx mori silk showed optically induced effects similar to those found in other polymers incorporating azobenzene moieties. Optically induced anisotropy in refractive index reached 7 × 10−3 with 18 J cm−2 required to reach 50% of steady state. Holograms were formed with diffraction efficiencies reaching 2.5%. The holograms were accompanied by surface relief gratings and measurements of the mechanical properties of films with surface relief gratings showed that the raised areas were more adhesive than the lower areas. We also demonstrated the fidelity of holographic images. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Does aboveground vegetation composition resemble soil seed bank during succession in specialized vegetation on gypsum soil?
Authors: Martinez‐Duro Esmeralda , Luzuriaga Arantzazu L. , Ferrandis Pablo , Escudero Adrián , Herranz José M. 
Published: November 2011

AbstractThis paper evaluates the aboveground vegetation in relation to the soil seed bank throughout a 60‐year succession process following agricultural abandonment in a semi‐arid Mediterranean gypsum habitat. There is little information regarding the relationship between these two community components in the context of succession on semi‐arid gypsum soils. Aboveground vegetation and the corresponding seed bank of gypsum plant communities were sampled through a chronosequence of 24 abandoned fields. Generalized linear models were used to model seed species richness and density, redundancy analyses to model the effect of time since abandonment and the effect of soil physicochemical parameters on seed bank species composition, and Mantel tests to analyze resemblance between above‐ and belowground species composition. In this last case, the effect of time since abandonment was controlled using a partial Mantel test. Mantel correlograms using time intervals instead of distances were used to describe the resemblance of above‐ to belowground species occurrence in different aged fields. No significant variability in seed species richness, seed density, or species composition due to time since abandonment was found. Differences in seed species composition were mainly due to small spatial scale predictors such as slope and soil calcium content. High correlations between species composition in the soil seed bank and the aboveground vegetation were detected during succession. The lack of a significant trend in aboveground species replacement over time was also reflected in seed bank composition. We concluded that the rapid establishment of strict gypsophyte species relied mainly on the long‐term persistence of these species in the seed bank.
Separation of Lipid Classes by HPLC on a Cyanopropyl Column
Authors: Olsson Petter , Holmbäck Jan , Herslöf Bengt 
Published: November 2011

AbstractA new method for the separation and identification of lipid classes by normal‐phase HPLC on a cyanopropyl column is described. The use of a simple binary gradient, with toluene as a component, provided a rapid separation of non‐polar as well as phospholipid classes. The inherent small differences in performances between possible non‐polar eluent components of the gradient, such as hexane, heptane, and iso‐octane, had a pronounced impact on retention times for individual phospholipid classes. Separation of molecular species within a lipid class could also be observed.
Density is in the eye of the beholder: visual versus semi-automated assessment of breast density on standard mammograms
Authors: Lobbes M. B. I. , Cleutjens J. P. M. , Lima Passos V. , Frotscher C. , Lahaye M. J. , Keymeulen K. B. M. I. , Beets-Tan R. G. , Wildberger J. , Boetes C. 
Published: November 2011

Abstract

Objectives
Visual inspection is generally used to assess breast density. Our study aim was to compare visual assessment of breast density of experienced and inexperienced readers with semi-automated analysis of breast density.

Methods
Breast density was assessed by an experienced and an inexperienced reader in 200 mammograms and scored according to the quantitative BI-RADS classification. Breast density was also assessed by dedicated software using a semi-automated thresholding technique. Agreement between breast density classification of both readers as well as agreement between their assessment versus the semi-automated analysis as reference standard was expressed as the weighted kappa value.

Results
Using the semi-automated analysis, agreement between breast density measurements of both breasts in both projections was excellent (ICC >0.9, P < 0.0001). Reproducibility of the semi-automated analysis was excellent (ICC >0.8, P < 0.0001). The experienced reader correctly classified the BI-RADS breast density classification in 58.5% of the cases. Classification was overestimated in 35.5% of the cases and underestimated in 6.0% of the cases. Results of the inexperienced reader were less accurate. Agreement between the classification of both readers versus the semi-automated analysis was considered only moderate with weighted kappa values of 0.367 (experienced reader) and 0.232 (inexperienced reader).

Conclusion
Visual assessment of breast density on mammograms is inaccurate and observer-dependent.