bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti-Hyperglycemic Effect of Chebulagic Acid from the Fruits of Terminalia chebula Retz
Authors: Huang Yi-Na , Zhao Dong-Dong , Gao Bo , Zhong Kai , Zhu Rui-Xue , Zhang Yan , Xie Wang-Jun , Jia Li-Rong , Gao Hong
Published: May 2012

In the present study, we firstly compared rat intestinal α-glucosidase inhibitory activity by different ethanol-aqueous extractions from the dried fruits of Terminalia chebula Retz. The enzymatic assay showed that the 80% ethanol extract was more potent against maltase activity than both 50% and 100% ethanol extracts. By HPLC analysis, it was determined that the 80% ethanol extract had a higher content of chebulagic acid than each of 50% or 100% ethanol extract. Next, we investigated how efficiently chebulagic acid could inhibit sugar digestion by determining the glucose level on the apical side of the Caco-2 cell monolayer. The result showed that the maltose-hydrolysis activity was down-regulated by chebulagic acid, which proved to be a reversible inhibitor of maltase in Caco-2 cells. On the other hand, chebulagic acid showed a weak inhibition of sucrose-hydrolysis activity. Meanwhile, chebulagic acid did not have an obvious influence on intestinal glucose uptake and was not effective on glucose transporters. Further animal studies revealed that the oral administration of chebulagic acid (100 mg/kg body weight) significantly reduced postprandial blood glucose levels by 11.1% in maltose-loaded Sprague-Dawley (SD) rats compared with the control group, whereas the oral administration of chebulagic acid did not show a suppressive effect on postprandial hyperglycemia in sucrose- or glucose-loaded SD-rats. The results presented here suggest that chebulagic acid from T. chebula can be used to control blood glucose and manage type 2 diabetes, although clinical trials are needed.
Strained Silicon Photonics
Authors: Schriever Clemens , Bohley Christian , Schilling Jörg , Wehrspohn Ralf B.
Published: May 2012

A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.
4-Thiazolidinones in Heterocyclic Synthesis: Synthesis of Novel Enaminones, Azolopyrimidines and 2-Arylimino-5-arylidene-4-thiazolidinones
Authors: Behbehani Haider , Ibrahim Hamada Mohamed
Published: May 2012

The 4-thiazolidinones 3a–d were used as a key intermediates for the synthesis of 2-arylimino-5-arylidene-4-thiazolidinones derivatives 7a–p via nucleophilic addition reactions with the arylidene malononitrile. Moreover the 4-thiazolidinones 3a and 3c condensed with the DMF-DMA to form the corresponding enamines 8 and 9 depending on the reaction conditions. Otherwise the 4-thiazolidinone 3b reacts regioselectively with DMF-DMA to afford the enaminones 10 and 11, respectively. The latter reacts with many heterocyclic amines affording polyfunctionally substituted fused pyrimidine derivatives 13–18. The enamine 8b was also reacted with the 3-amino-1,2,4-triazole to afford the acyclic product 19, which could not be further cyclized to the corresponding tricyclic system 20. Moreover the 4-thiazolidinone 3c reacted with the benzenediazonium chloride to afford the arylhydrazones 12. The X-ray single crystal technique was employed in this study for structure elucidation and Z/E potential isomerism configuration determination. The X-ray crystallographic analyses of eight products could be obtained, thus establishing with certainty the structures proposed in this work.
Flexible Graphite-on-Paper Piezoresistive Sensors
Authors: Ren Tian-Ling , Tian He , Xie Dan , Yang Yi
Published: May 2012

We demonstrate novel graphite-on-paper piezoresistive devices. The graphite was used as sensing component. The fabrication process can be finished in a short time with simple tools (e.g., a scissor and a pencil). A small array of six paper-based piezoresistive devices is made. The whole device is flexible. The test results showed that the change of resistance was proportional to the applied force. A paper-based weighing balance was also made as an example of applications. This novel array of paper-based piezoresistive devices will open wide applications in force and acceleration sensing areas.
Geometric and Colour Data Fusion for Outdoor 3D Models
Authors: Merchán Pilar , Adán Antonio , Salamanca Santiago , Domínguez Vicente , Chacón Ricardo
Published: May 2012

This paper deals with the generation of accurate, dense and coloured 3D models of outdoor scenarios from scanners. This is a challenging research field in which several problems still remain unsolved. In particular, the process of 3D model creation in outdoor scenes may be inefficient if the scene is digitalized under unsuitable technical (specific scanner on-board camera) and environmental (rain, dampness, changing illumination) conditions. We address our research towards the integration of images and range data to produce photorealistic models. Our proposal is based on decoupling the colour integration and geometry reconstruction stages, making them independent and controlled processes. This issue is approached from two different viewpoints. On the one hand, given a complete model (geometry plus texture), we propose a method to modify the original texture provided by the scanner on-board camera with the colour information extracted from external images taken at given moments and under specific environmental conditions. On the other hand, we propose an algorithm to directly assign external images onto the complete geometric model, thus avoiding tedious on-line calibration processes. We present the work conducted on two large Roman archaeological sites dating from the first century A.D., namely, the Theatre of Segobriga and the Fori Porticus of Emerita Augusta, both in Spain. The results obtained demonstrate that our approach could be useful in the digitalization and 3D modelling fields.
On the Impact of Localization and Density Control Algorithms in Target Tracking Applications for Wireless Sensor Networks
Authors: Campos Andre N. , Souza Efren L. , Nakamura Fabiola G. , Nakamura Eduardo F. , Rodrigues Joel J. P. C.
Published: May 2012

Target tracking is an important application of wireless sensor networks. The networks’ ability to locate and track an object is directed linked to the nodes’ ability to locate themselves. Consequently, localization systems are essential for target tracking applications. In addition, sensor networks are often deployed in remote or hostile environments. Therefore, density control algorithms are used to increase network lifetime while maintaining its sensing capabilities. In this work, we analyze the impact of localization algorithms (RPE and DPE) and density control algorithms (GAF, A3 and OGDC) on target tracking applications. We adapt the density control algorithms to address the k-coverage problem. In addition, we analyze the impact of network density, residual integration with density control, and k-coverage on both target tracking accuracy and network lifetime. Our results show that DPE is a better choice for target tracking applications than RPE. Moreover, among the evaluated density control algorithms, OGDC is the best option among the three. Although the choice of the density control algorithm has little impact on the tracking precision, OGDC outperforms GAF and A3 in terms of tracking time.
Ubiquitous Mobile Knowledge Construction in Collaborative Learning Environments
Authors: Baloian Nelson , Zurita Gustavo
Published: May 2012

Knowledge management is a critical activity for any organization. It has been said to be a differentiating factor and an important source of competitiveness if this knowledge is constructed and shared among its members, thus creating a learning organization. Knowledge construction is critical for any collaborative organizational learning environment. Nowadays workers must perform knowledge creation tasks while in motion, not just in static physical locations; therefore it is also required that knowledge construction activities be performed in ubiquitous scenarios, and supported by mobile and pervasive computational systems. These knowledge creation systems should help people in or outside organizations convert their tacit knowledge into explicit knowledge, thus supporting the knowledge construction process. Therefore in our understanding, we consider highly relevant that undergraduate university students learn about the knowledge construction process supported by mobile and ubiquitous computing. This has been a little explored issue in this field. This paper presents the design, implementation, and an evaluation of a system called MCKC for Mobile Collaborative Knowledge Construction, supporting collaborative face-to-face tacit knowledge construction and sharing in ubiquitous scenarios. The MCKC system can be used by undergraduate students to learn how to construct knowledge, allowing them anytime and anywhere to create, make explicit and share their knowledge with their co-learners, using visual metaphors, gestures and sketches to implement the human-computer interface of mobile devices (PDAs).
La gestación bajomedieval del derecho de resistencia en Castilla: modelos interpretativos
Authors: Nieto Soria José Manuel
Published: May 2012

El derecho de resistencia suele ser objeto de atención preferente a partir de la expansión que experimentó en el pensamiento político humanista. Sin embargo, tal como se ha pretendido mostrar en este trabajo, tuvo una signifi cativa presencia en la teoría y en la práctica política de la Castilla bajomedieval. La consideración de esta teoría y de esta práctica ubicada en su contexto cultural permite establecer, tal como se ha planteado, cuatro modelos teóricos, dentro de cada uno de los cuales el derecho de resistencia es susceptible de recibir una interpretación particular. De entre esos cuatro modelos establecidos y que, en esencia, pueden simplifi carse en el de la mediación teológico-eclesiástica, el del pacto, el del absolutismo y el de la libertad individual, resulta evidente el largo predominio del primero de ellos. Este predominio, además de constatarse desde el punto de vista cronológico, también se comprueba por la presencia de su toma en consideración en el marco de aplicación dominante de alguno de los otros modelos.
Os Sousões contra Afonso VI : Memória histórica ou «apostila de mal dizer»?
Authors: Miranda José Carlos Ribeiro
Published: May 2012

No presente estudo pretende-se apurar o estatuto de alguns episódios do Livro Velho de Linhagens que apontam para uma ligação estreita da linhagem portuguesa dos Sousões aos meios condais e régios castelhanos num período anterior ao século XII, e também para uma certa hostilidade desta linhagem relativamente a Afonso VI e ao seu neto Afonso Henriques. A conclusão é que se trata de uma construção ficcional de intenção caluniosa, em sintonia, no entanto, com os pontos de vista dos promotores deste livro de linhagens.
Obéissance et désobéissance dans le Victorial de Gutierre Díaz de Games
Authors: Gonzalez Sara
Published: May 2012

Ce travail a pour but de montrer les procédés mis en oeuvre par Gutierre Díaz de Games afin de concilier les diverses actions dissidentes de Pero Niño avec le modèle de héros chevaleresque qu’il est censé incarner. Nous verrons comment l’auteur réussit à tourner les différents épisodes d’insubordination du personnage à son avantage : l’insoumission à un ordre est finalement toujours soumission à un autre ordre.
Modèles d'appariement en économie
Authors: Chiappori Pierre-André
Published: May 2012

Résumé Si les modèles d’appariement sont utilisés en économie depuis plus d’un demi-siècle, ils suscitent depuis quelques années un renouveau d’intérêt. Cet article se propose tout d’abord de présenter quelques-uns de ces développements récents, en restreignant notre attention aux modèles à utilité transférable. En second lieu, nous montrons que la principale limitation de ces modèles – l’indépendance entre la décision collective et les rapports de force internes aux groupes considérés – peut être dépassée par une généralisation du modèle. Nous présentons une telle généralisation et discutons ses propriétés.
Mobilités, inégalités et trajectoires professionnelles
Authors: Beck Simon , Kamionka Thierry
Published: May 2012

Résumé Nous présentons, dans cet article, une étude de la mobilité et des trajectoires professionnelles à partir d’un panel de données inédit en France. La base fh-dads , issue du rapprochement du fichier historique de Pôle Emploi et des Déclarations annuelles de données sociales, nous permet en effet de mettre en évidence les stabilités et les instabilités de l’emploi. Afin de prendre en compte la présence de l’hétérogénéité inobservée, nous utilisons un modèle de transition à effets fixes développé par Magnac [2000] pour représenter les transitions sur le marché du travail. Nos résultats font apparaître une grande hétérogénéité des mobilités entre les individus qui ne reflète pas exclusivement les différences de caractéristiques individuelles. Cette hétérogénéité entraîne alors une évolution particulière des mobilités, sensible à la conjoncture économique et reliée à l’évolution des inégalités.
La protection de l'emploi influence-t-elle les flux migratoires à destination des pays de l'ocde ?
Authors: Bazillier Rémi , Moullan Yasser
Published: May 2012

Résumé Nous montrons que les institutions sur le marché du travail, et tout particulièrement la protection de l’emploi constituent un déterminant important des flux migratoires. Contrairement à ce qui est souvent annoncé, les migrants ne sont pas à la recherche de législations plus protectrices. Au contraire, nous montrons que le différentiel de protection de l’emploi a un impact négatif sur les flux de migration. Ce différentiel lorsqu’il est élevé s’apparente à une capacité d’intégration sur le marché du travail plus faible jouant négativement sur la migration. Ces résultats sont obtenus en prenant en compte la forte proportion de flux nuls en utilisant la méthode d’Heckman en deux étapes et la méthode de Poisson. Nous contrôlons également d’un possible biais d’endogénéité en instrumentant notre variable de protection de l’emploi.
Immigration, vieillissement démographique et financement de la protection sociale
Authors: Chojnicki Xavier , Ragot Lionel
Published: May 2012

Résumé L’immigration est souvent avancée comme l’un des instruments d’adaptation des économies confrontées au phénomène du vieillissement démographique. Dans cet article, nous évaluons, à l’aide d’un modèle d’équilibre général calculable dynamique, la contribution d’une politique migratoire à la réduction du fardeau fiscal lié au vieillissement démographique en France. Globalement, ces effets sont positifs et le sont d’autant plus, à court-moyen terme, que la politique migratoire est sélective. À long terme, ces effets bénéfiques peuvent disparaître pour une politique très sélective. Cependant, les gains pour les finances publiques provenant de flux migratoires nets plus conséquents sont relativement modérés en comparaison des évolutions démographiques qu’ils impliquent.
La dynamique d'ajustement des taux de change réels dans la zone franc CFA
Authors: Couharde Cécile , Coulibaly Issiaka , Damette Olivier
Published: May 2012

Résumé L’objet de cet article est d’analyser les modalités de convergence des taux de change effectifs réels vers leurs niveaux d’équilibre, dans les pays de la zone franc sur la période 1985-2007. À cette fin, nous estimons un modèle à correction d’erreur à transition lisse en panel afin de prendre en compte l’existence de phénomènes de non-linéarités. En particulier, nous montrons que le processus d’ajustement des taux de change effectifs réels dans la zone cfa est bien asymétrique, mais que cette asymétrie diffère toutefois fortement selon les pays. Ce dernier résultat tend à montrer la difficulté d’appliquer une politique de change unique dans la zone cfa et plaide plutôt en faveur d’un renforcement de la coordination et de l’harmonisation des politiques économiques entre les pays de la zone.
Les déterminants des prix du carbone
Authors: Creti Anna , Jouvet Pierre-André , Mignon Valérie
Published: May 2012

Résumé L’objectif de cet article est d’étudier les déterminants des prix du carbone durant les deux phases du système d’échange des quotas européens concernant les permis d’émission des gaz à effet de serre ( eu ets ). Plus spécifiquement, en considérant les contrats sur futures à fréquence quotidienne, nous testons si les déterminants des prix du carbone identifiés pour la phase I sont toujours valables pour la phase II et évoluent suivant une relation stable de long terme. En tenant compte de la rupture intervenue en 2006 sur le marché des permis, nous montrons qu’une relation de coïntégration existe pour les deux phases de l’ eu ets . La nature de cette relation d’équilibre est toutefois différente entre les deux sous-périodes, avec un rôle croissant des fondamentaux durant la phase II. Le calcul des valeurs d’équilibre montre, en outre, que les prix du carbone tendent à être sous-évalués depuis fin 2009.
Montesquieu et la nouvelle économie politique
Authors: Ferey Samuel
Published: May 2012

Résumé L’objet de l’article est de proposer une lecture de l’œuvre de Montesquieu inspirée des récents développements de la New Political Economy . En effet, les interactions entre phénomènes économiques et phénomènes politiques sont constantes au sein de De l’esprit des lois . Plus précisément, on met en évidence le rôle central des inégalités et de la redistribution dans la stabilité et l’instabilité des régimes politiques chez Montesquieu. En insistant plus particulièrement sur les républiques, on montre alors que cette lecture permet de proposer une interprétation de la notion de vertu chez Montesquieu comme un certain degré d’aversion à l’inégalité qui doit être modéré sous peine de générer de l’instabilité politique.
Le réclamisme
Authors: Lenoble Benoît
Published: May 2012

Résumé L’événement médiatique contemporain est le résultat d’un processus d’élaboration, de diffusion et de légitimation dans le temps, le quotidien et les représentations des sociétés. Sa construction par les médias modernes et son insertion dans le monde social s’observent, en France durant la seconde moitié du xix e siècle, à travers les manifestations réclamistes des journaux parisiens et régionaux de grande diffusion. Ces derniers expérimentent et améliorent des pratiques renouvelées de vente et de promotion, des jeux-concours aux prix conséquents, des lancements de romans-feuilletons à coups d’affiches illustrées et de fascicules gratuits, des compétitions sportives, des souscriptions publiques, des manifestations populaires ou de relations publiques. Ces opérations autopromotionnelles sont montées de toutes pièces par des quotidiens à bon marché qui cherchent à établir ou renforcer leur position commerciale et leur notoriété médiatique. Enchaînées et croisées, faisant parler d’elles dans et autour des espaces imprimé et social, montant en puissance médiatique et culturelle, elles font événement dans la presse de grande diffusion et deviennent événements dans le monde social. Leur normalisation, à un moment d’extension de la culture de masse, est travaillée par les journaux, qui se concurrencent, et leurs rédacteurs qui les grossissent dans leurs récits, en justifient l’existence et en exagèrent la portée. Chemin faisant, ces manifestations frappent les lecteurs et les populations qui s’habituent et participent à ces opérations, qui les intègrent dans leur façon de comprendre le monde et la société. À la fois dynamiques et matricielles, elles rythment le temps et structurent l’espace public en tant qu’événements.
Les objets du poison de l'antiquité à nos jours
Authors: Bodiou Lydie , Chauvaud Frédéric , Soria Myriam
Published: May 2012

Résumé Le poison et ses crimes fascinent, inquiètent et soulèvent quantité d’interrogations depuis les temps les plus anciens. Incarnés par des coupables dont les gestes et les intentions funestes ont monopolisé l’attention des observateurs, leurs mystères résident aussi dans les objets qui les entourent. Or l’histoire matérielle de l’empoisonnement tend à révéler que, même si chaque période se caractérise par un ensemble d’objets lui donnant une coloration unique et un sens particulier, les instruments du poison sont ceux qui peuplent le quotidien des empoisonneurs comme de leurs victimes. Si la banalité de l’objet empoisonné renforce le caractère sournois du crime, elle s’oppose aussi à l’originalité et à la puissance des objets qui le détectent ou le dénoncent, inscrits entre magie et sciences. Quelques détours historiques dans le territoire des choses empoisonnées, de l’Antiquité grecque à nos jours, montrent ainsi que la confrontation de la matière à la chair témoigne autrement des calculs qui précèdent et accompagnent l’empoisonnement, mais aussi des craintes et de la compréhension des dangers qui animent les victimes potentielles et leurs défenseurs.
Aceros avanzados de alta resistencia en la industria automovilística
Authors: Galán J. , Samek L. , Verleysen P. , Verbeken K. , Houbaert Y.
Published: May 2012

La industria del automóvil se enfrenta a una creciente demanda de vehículos de pasajeros más eficientes. Con el fin de disminuir el consumo de energía y la contaminación ambiental, el peso del vehículo tiene que ser reducido, al mismo tiempo que se garantizan altos niveles de seguridad. Ante esta situación, la elección de material se convierte en una decisión crucial en el diseño del vehículo. Como respuesta a las necesidades del sector automovilístico, nuevos aceros avanzados y de alta resistencia, han sido desarrollados por la industria siderúrgica. Dichos tipos de acero ofrecen un excelente equilibrio de precio, peso y propiedades mecánicas.
The influence of temperature on the metabolic regulation and gas exchange of the Highveld scorpion, Opistophthalmus latimanus ( Koch ) ( Scorpionidae )
Authors: Van Aardt Willie J. , Mienie Japie , Le Roux J.M.
Published: May 2012

Adult scorpions (2.4g – 4.5 kg) were collected near Potchefstroom (26° .55’10” – 27° 10” 5”). Oxygen consumption rate (MO2) and carbon dioxide production rate (MCO2) were measured together with the metabolism of injected radioactive glucose.
Comparative histomorphological assessment of the testes of two Clarias species from the Okavango Delta, Botswana
Authors: Mokae M.L. , Wagenaar G.M. , Smit Nico J.
Published: May 2012

The testes of two Clarias species from the Okavango Delta were assessed because of their colour differences. Three histological stains were used to enhance the cellular detail in the testes. The lobules and different cell types were detected and described and used for the determination of sexual maturity.
Multi-Physics Analyses of Selected Civil Engineering Concrete Structures
Authors: Kruis J. , Koudelka T. , Krejcˇí T.
Published: May 2012

This paper summarizes suitable material models for creep and damage of concrete which are coupled with heat and moisture transfer. The fully coupled approach or the staggered coupling is assumed. Governing equations are spatially dis-cretized by the finite element method and the temporal discretization is done by the generalized trapezoidal method. Systems of non-linear algebraic equations are solved by the Newton method. Development of an efficient and extensible computer code based on the C++ programming language is described. Finally, successful analyses of two real engineering problems are described.
Vlasov-Fokker-Planck Simulations for High-Power Laser-Plasma Interactions
Authors: Weng Su-Ming , Sheng Zheng-Ming , Xu Hui , Zhang Jie
Published: May 2012

A review is presented on our recent Vlasov-Fokker-Planck (VFP) simulation code development and applications for high-power laser-plasma interactions. Numerical schemes are described for solving the kinetic VFP equation with both electron-electron and electron-ion collisions in one-spatial and two-velocity (1D2V) coordinates. They are based on the positive and flux conservation method and the finite volume method, and these two methods can insure the particle number conservation. Our simulation code can deal with problems in high-power laser/beam-plasma interactions, where highly non-Maxwellian electron distribution functions usually develop and the widely-used perturbation theories with the weak anisotropy assumption of the electron distribution function are no longer in point. We present some new results on three typical problems: firstly the plasma current generation in strong direct current electric fields beyond Spitzer-Härm’s transport theory, secondly the inverse bremsstrahlung absorption at high laser intensity beyond Langdon’s theory, and thirdly the heat transport with steep temperature and/or density gradients in laser-produced plasma. Finally, numerical parameters, performance, the particle number conservation, and the energy conservation in these simulations are provided.
Simulating an Elastic Ring with Bend and Twist by an Adaptive Generalized Immersed Boundary Method
Authors: Griffith Boyce E. , Lim Sookkyung
Published: May 2012

Many problems involving the interaction of an elastic structure and a viscous fluid can be solved by the immersed boundary (IB) method. In the IB approach to such problems, the elastic forces generated by the immersed structure are applied to the surrounding fluid, and the motion of the immersed structure is determined by the local motion of the fluid. Recently, the IB method has been extended to treat more general elasticity models that include both positional and rotational degrees of freedom. For such models, force and torque must both be applied to the fluid. The positional degrees of freedom of the immersed structure move according to the local linear velocity of the fluid, whereas the rotational degrees of freedom move according to the local angular velocity. This paper introduces a spatially adaptive, formally second-order accurate version of this generalized immersed boundary method. We use this adaptive scheme to simulate the dynamics of an elastic ring immersed in fluid. To describe the elasticity of the ring, we use an unconstrained version of Kirchhoff rod theory. We demonstrate empirically that our numerical scheme yields essentially second-order convergence rates when applied to such problems. We also study dynamical instabilities of such fluid-structure systems, and we compare numerical results produced by our method to classical analytic results from elastic rod theory.
Lattice BGK Model for Incompressible Axisymmetric Flows
Authors: Zhang Ting , Shi Baochang , Chai Zhenhua , Rong Fumei
Published: May 2012

In this paper, a lattice Boltzmann BGK (LBGK) model is proposed for simulating incompressible axisymmetric flows. Unlike other existing axisymmetric lattice Boltzmann models, the present LBGK model can eliminate the compressible effects only with the small Mach number limit. Furthermore the source terms of the model are simple and contain no velocity gradients. Through the Chapman-Enskog expansion, the macroscopic equations for incompressible axisymmetric flows can be exactly recovered from the present LBGK model. Numerical simulations of the Hagen-Poiseuille flow, the pulsatile Womersley flow, the flow over a sphere, and the swirling flow in a closed cylindrical cavity are performed. The results agree well with the analytic solutions and the existing numerical or experimental data reported in some previous studies.
A Discussion on Two Stochastic Elliptic Modeling Strategies
Authors: Wan Xiaoliang
Published: May 2012

Based on the study of two commonly used stochastic elliptic models: I: − ∇· (a(x,w)·∇u(x,w)) = f (x) and II: − ∇·(a(x,w)◊∇u(x,w)) = f (x), we constructed a new stochastic elliptic model III: −∇ ◊ ((a−1)·(−1)◊∇u(x,w)) = f (x), in. The difference between models I and II is twofold: a scaling factor induced by the way of applying the Wick product and the regularization induced by the Wick product itself. In, we showed that model III has the same scaling factor as model I. In this paper we present a detailed discussion about the difference between models I and III with respect to the two characteristic parameters of the random coefficient, i.e., the standard deviation σ and the correlation length lc. Numerical results are presented for both one- and two-dimensional cases.
Invited review: The new spin foam models and quantum gravity
Authors: Perez Alejandro
Published: May 2012

In this article, we give a systematic definition of the recently introduced spin foam models for four-dimensional quantum  gravity, reviewing the main results on their semiclassical limit on fixed discretizations.Received: 17 October 2011,  Accepted: 18 March 2012; Edited by: J. Pullin; Reviewed by: L. Freidel, Perimeter Institute for Theoretical Physics, Waterloo, Canada;  DOI: http://dx.doi.org/10.4279/PIP.040004Cite as: A. Perez, Papers in Physics 4, 040004 (2012)
Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements
Authors: Klonecki A. , Pommier M. , Clerbaux C. , Ancellet G. , Cammas J.-P. , Coheur P.-F. , Cozic A. , Diskin G. S. , Hadji-Lazaro J. , Hauglustaine D. A. , Hurtmans D. , Khattatov B. , Lamarque J.-F. , Law K. S. , Nedelec P. , Paris J.-D. , Podolske J. R. , Prunet P. , Schlager H. , Szopa S. , Turquety S.
Published: May 2012

Abstract. This work evaluates the IASI CO product against independent in-situ aircraft data from the MOZAIC program and the POLARCAT aircraft campaign. The validation is carried out by analysing the impact of assimilation of eight months of IASI CO columns retrieved for the period of May to December 2008 into the global chemistry transport model LMDz-INCA. A modelling system based on a sub-optimal Kalman filter was developed and a specific treatment that takes into account the representativeness of observations at the scale of the model grid is applied to the IASI CO columns and associated errors before their assimilation in the model. Comparisons of the assimilated CO profiles with in situ CO measurements indicate that the assimilation leads to a considerable improvement of the model simulations in the middle troposphere as compared with a control run with no assimilation. Model biases in the simulation of background values are reduced and improvement in the simulation of very high concentrations is observed. The improvement is due to the transport by the model of the information present in the IASI CO retrievals. Our analysis also shows the impact of assimilation of CO on the representation of transport into the Arctic region during the POLARCAT summer campaign. A considerable increase in CO mixing ratios over the Asian source region was observed when assimilation was used leading to much higher values of CO during the cross-pole transport episode. These higher values are in good agreement with data from the POLARCAT flights that sampled this plume.
Aerosol charging state at an urban site: new analytical approach and implications for ion-induced nucleation
Authors: Gagné S. , Leppä J. , Petäjä T. , McGrath M. J. , Vana M. , Kerminen V.-M. , Laakso L. , Kulmala M.
Published: May 2012

Abstract. The charging state of aerosol populations was determined using an Ion-DMPS in Helsinki, Finland between December 2008 and February 2010. We extrapolated the charging state and calculated the ion-induced nucleation fraction to be around 1.3 % ± 0.4 % at 2 nm and 1.3 % ± 0.5 % at 1.5 nm, on average. We present a new method to retrieve the average charging state for a new particle formation event, at a given size and polarity. We improve the uncertainty assessment and fitting technique used previously with an Ion-DMPS. We also use a new theoretical framework that allows for different concentrations of small ions for different polarities (polarity asymmetry). We extrapolate the ion-induced fraction using polarity symmetry and asymmetry. Finally, a method to calculate the growth rates from the behaviour of the charging state as a function of the particle diameter using polarity symmetry and asymmetry is presented and used on a selection of new particle formation events.
Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables
Authors: Rannik Ü. , Altimir N. , Mammarella I. , Bäck J. , Rinne J. , Ruuskanen T. M. , Hari P. , Vesala T. , Kulmala M.
Published: May 2012

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. Canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, focusing on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time- scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. This was also confirmed by the statistical analysis that did not link measured sesquiterpene concentration with ozone deposition. It was concluded that chemical reactions with monoterpenes, or other removal mechanisms such as surface reactions, play a role as ozone non-stomatal sink inside canopy.
In-canopy gas-phase chemistry during CABINEX 2009: sensitivity of a 1-D canopy model to vertical mixing and isoprene chemistry
Authors: Bryan A. M. , Bertman S. B. , Carroll M. A. , Dusanter S. , Edwards G. D. , Forkel R. , Griffith S. , Guenther A. B. , Hansen R. F. , Helmig D. , Jobson B. T. , Keutsch F. N. , Lefer B. L. , Pressley S. N. , Shepson P. B. , Stevens P. S. , Steiner A. L.
Published: May 2012

Abstract. Vegetation emits large quantities of biogenic volatile organic compounds (BVOC). At remote sites, these compounds are the dominant precursors to ozone and secondary organic aerosol (SOA) production, yet current field studies show that atmospheric models have difficulty in capturing the observed HOx cycle and concentrations of BVOC oxidation products. In this manuscript, we simulate BVOC chemistry within a forest canopy using a one-dimensional canopy-chemistry model (Canopy Atmospheric CHemistry Emission model; CACHE) for a mixed deciduous forest in northern Michigan during the CABINEX 2009 campaign. We find that the base-case model, using fully-parameterized mixing and the simplified biogenic chemistry of the Regional Atmospheric Chemistry Model (RACM), underestimates daytime in-canopy vertical mixing by 50–70% and by an order of magnitude at night, leading to discrepancies in the diurnal evolution of HOx, BVOC, and BVOC oxidation products. Implementing observed micrometeorological data from above and within the canopy substantially improves the diurnal cycle of modeled BVOC, particularly at the end of the day, and also improves the observation-model agreement for some BVOC oxidation products and OH reactivity. We compare the RACM mechanism to a version that includes the Mainz isoprene mechanism (RACM-MIM) to test the model sensitivity to enhanced isoprene degradation. RACM-MIM simulates higher concentrations of both primary BVOC (isoprene and monoterpenes) and oxidation products (HCHO, MACR + MVK) compared with RACM simulations. Additionally, the revised mechanism alters the OH concentrations and increases HO2. These changes generally improve agreement with HOx observations yet overestimate BVOC oxidation products, indicating that this isoprene mechanism does not improve the representation of local chemistry at the site. Overall, the revised mechanism yields smaller changes in BVOC and BVOC oxidation product concentrations and gradients than improving the parameterization of vertical mixing with observations, suggesting that uncertainties in vertical mixing parameterizations are an important component in understanding observed BVOC chemistry.
Factor analysis of combined organic and inorganic aerosol mass spectra from high resolution aerosol mass spectrometer measurements
Authors: Sun Y. L. , Zhang Q. , Schwab J. J. , Yang T. , Ng N. L. , Demerjian K. L.
Published: May 2012

Abstract. The high resolution mass spectra of organic and inorganic aerosols from aerosol mass spectrometer (AMS) measurements were first combined into positive matrix factorization (PMF) analysis to investigate the sources and evolution processes of atmospheric aerosols. The new approach is able to study the mixing of organic aerosols (OA) and inorganic species, the acidity of OA factors, and the fragment ion patterns related to photochemical processing. In this study, PMF analysis of the unified AMS spectral matrices resolved 8 factors for the submicron aerosols measured at Queens College in New York City in summer 2009. The hydrocarbon-like OA (HOA) and cooking OA (COA) contain very minor inorganic species, indicating the different sources and mixing characteristics between primary OA and secondary species. The two factors that are primarily ammonium sulfate (SO4-OA) and ammonium nitrate (NO3-OA), respectively, are overall neutralized, of which the OA in SO4-OA shows the highest oxidation state (O/C = 0.69) among OA factors. The semi-volatile oxygenated OA comprises two components, i.e., a less oxidized (LO-OOA) and a more oxidized (MO-OOA). The MO-OOA represents a local photochemical product with the diurnal profile exhibiting a pronounced noon peak, consistent with those of formaldehyde (HCHO) and Ox (= O3+NO2). The much higher NO+/NO2+ fragment ion ratio in MO-OOA than that from ammonium nitrate alone provides evidence for the formation of organic nitrates. The amine-related nitrogen-enriched OA (NOA) contains ~25% of acidic inorganic salts, elucidating the formation of secondary OA from amines in acidic environments. The size distributions derived from 3-dimensional size-resolved mass spectra show distinct diurnal evolving behaviors for different OA factors, but overall a progressing evolution from smaller to larger particle mode as a function of oxidation states. Our results demonstrate that PMF analysis by incorporating inorganic aerosols is of importance for gaining more insights into the sources and processes, mixing characteristics, and acidity of OA.
Light and temperature effect on δ11B and B/Ca ratios of the zooxanthellate coral Acropora sp.: results from culturing experiments
Authors: Dissard D. , Douville E. , Reynaud S. , Juillet-Leclerc A. , Montagna P. , Louvat P. , McCulloch M.
Published: May 2012

Abstract. The boron isotopic composition (δ11B) of marine carbonates (e.g. corals) has been established as a reliable proxy for paleo-pH, with the strong correlation between δ11B of marine calcifiers and seawater pH being now well documented. However, further investigations are needed in order to better quantify other environmental parameters potentially impacting boron isotopic composition and boron concentration into coral aragonite. To achieve this goal the tropical scleractinian coral Acropora sp. was cultured under 3 different temperature (22, 25 and 28 °C) and two light conditions (200 and 400 μmol photon m−2 s−1). The δ11B indicates an internal increase in pH from ambient seawater under both light conditions. Changes in light intensities from 200 to 400 μmol photon m−2 s−1 could bias pH reconstructions by about 0.05 units. For both light conditions, a significant impact of temperature on δ11B can be observed between 22 and 25 °C corresponding to enhancements of about 0.02 pH-units, while no further δ11B increase can be observed between 25 and 28 °C. This non-linear temperature effect complicates the determination of a correcting factor. B/Ca ratios decrease with increasing light, confirming the decrease in pH at the site of calcification under enhanced light intensities. When all the other parameters are maintained constant, boron concentrations in Acropora sp. increase with increasing temperature and increasing carbonate ions concentrations. These observations contradict previous studies where B/Ca in corals was found to vary inversely with temperature suggesting that the controlling factors driving boron concentrations have not yet been adequately identified and might be influenced by other seawater variables and species specific responses.
Inclusion of vegetation in the Town Energy Balance model for modeling urban green areas
Authors: Lemonsu A. , Masson V. , Shashua-Bar L. , Erell E. , Pearlmutter D.
Published: May 2012

Abstract. Cities impact both local climate, through urban heat islands, and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representation into urban models will allow to address more accurately these questions. This paper presents an improvement of the TEB urban canopy model. Vegetation is directly included inside the canyon, allowing shadowing of grass by buildings, better representation of urban canopy form, and, a priori, a more accurate simulation of canyon air microclimate. The development is performed so that any vegetation model can be used to represent the vegetation part. Here the ISBA model is used. The model results are compared to microclimatic and evaporation measurements performed in small courtyards in a very arid region of Israel. Two experimental landscaping strategies – bare soil or irrigated grass in the courtyard – are observed and simulated. The new version of the model with integrated vegetation performs better than if vegetation is treated outside the canyon. Surface temperatures are closer to the observations, especially at night when radiative trapping is important. The integrated vegetation version simulates a more humid air inside the canyon. The microclimatic quantities are better simulated with this new version. This opens opportunities to study with better accuracy the urban microclimate, down to the micro (or canyon) scale.
Assessing trends in insured losses from floods in Spain 1971–2008
Authors: Barredo J. I. , Saurí D. , Llasat M. C.
Published: May 2012

Abstract. Economic impacts from floods have been increasing over recent decades, a fact often attributed to a changing climate. On the other hand, there is now a significant body of scientific scholarship all pointing towards increasing concentrations and values of assets as the principle cause of the increasing cost of natural disasters. This holds true for a variety of perils and across different jurisdictions. With this in mind, this paper examines the time history of insured losses from floods in Spain between 1971 and 2008. It assesses whether any discernible residual signal remains after adjusting the data for the increase in the number and value of insured assets over this period of time. Data on insured losses from floods were sourced from Consorcio de Compensación de Seguros (CCS). Although a public institution, CCS compensates homeowners for the damage produced by floods, and thus plays a role similar to that of a private insurance company. Insured losses were adjusted using two proxy measures: first, changes in the total amount of annual surcharges (premiums) paid by customers to CCS, and secondly, changes in the total value of dwellings per year. The adjusted data reveals no significant trend over the period 1971–2008 and serves again to confirm that at this juncture, societal influences remain the prime factors driving insured and economic losses from natural disasters.
Students hop, skip, and jump their way to understanding
Authors: elkin andrea christie
Published: May 2012

This month's topics include linking math learning to physical activity; summer Smallywood educational video games; Coaches' Corner; and where to find free CCSSM video clips.
Building theaters
Authors: Polly Drew
Published: May 2012

Seating arrangements in a theater offer a real-world context for fourth-grade students to work with factors, multiples, and divisibility.
A Little Area Challenge: A Sod Story
Authors: Myers Perla L. , Pelak Colleen N.
Published: May 2012

Implement this professional development workshop designed to help teachers excavate the concept of area, uncover misconceptions, and cultivate understanding.
Building Understanding of Decimal Fractions
Authors: D'Ambrosio Beatriz S. , Kastberg Signe E.
Published: May 2012

Using grids can help students overcome confusion about place value.
Human-animal relationships at sheep and cattle abattoirs
Authors: Coleman GJ , Rice M , Hemsworth PH
Published: May 2012

There are accumulating international data in a number of livestock industries that show that a negative attitude by stockpeople towards interacting with pigs, dairy cattle and poultry is correlated with increased levels of fear and stress in farm animals and in turn reduced animal productivity. While most of this research has been on-farm, one study has shown similar attitude-behaviour correlations in a pig abattoir. The major aim of this research was to examine the stockperson attitude-behaviour at sheep and cattle abattoirs. Twenty-two Australian abattoirs participated in the collection of stockperson attitudes and behaviour (81 stockpeople — 35 cattle stockpeople and 46 sheep stockpeople; six abattoirs slaughtering cattle, six slaughtering sheep and ten slaughtering both cattle and sheep). Several significant correlations between stockperson attitudes and behaviour were detected. In particular, the perceived pressures imposed by perceived lack of control over their actions, perceived time constraints, perceived effect of poor facilities and inappropriate beliefs about arousing livestock were all associated with frequent use of forceful handling behaviours by the stockperson. These results were similar to observations in pig abattoirs that have been reported previously. These relationships at cattle and sheep abattoirs indicate that there may be an opportunity to improve stockperson behaviour and consequently reduce stress in sheep and cattle at abattoirs by targeting attitudes (and behaviour) for improvement, with appropriate educational and training material in a way that is similar to the uses of such training with livestock species in farm settings.