bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-Assembled Matrix by Umbilical Cord Stem Cells
Authors: Karamichos Dimitrios , Rich Celeste B. , Hutcheon Audrey E.K. , Ren Ruiyi , Saitta Biagio , Trinkaus-Randall Vickery , Zieske James D.
Published: September 2011

Corneal integrity is critical for vision. Corneal wounds frequently heal with scarring that impairs vision. Recently, human umbilical cord mesenchymal stem cells (cord stem cells) have been investigated for tissue engineering and therapy due to their availability and differentiation potential. In this study, we used cord stem cells in a 3-dimensional (3D) stroma-like model to observe extracellular matrix organization, with human corneal fibroblasts acting as a control. For 4 weeks, the cells were stimulated with a stable Vitamin C (VitC) derivative ±TGF-b1. After 4 weeks, the mean thickness of the constructs was ~30 mm; however, cord stem cell constructs had 50% less cells per unit volume, indicating the formation of a dense matrix. We found minimal change in decorin and lumican mRNA, and a significant increase in perlecan mRNA in the presence of TGF-b1. Keratocan on the other hand decreased with TGF-b1 in both cell lineages. With both cell types, the constructs possessed aligned collagen fibrils and associated glycosaminoglycans. Fibril diameters did not change with TGF-b1 stimulation or cell lineage; however, highly sulfated glycosaminoglycans associated with the collagen fibrils significantly increased with TGF-b1. Overall, we have shown that cord stem cells can secrete their own extracellular matrix and promote the deposition and sulfation of various proteoglycans. Furthermore, these cells are at least comparable to commonly used corneal fibroblasts and present an alternative for the 3D in vitro tissue engineered model.
3-Chloro-N'-(2-hydroxy-4-pentadecylbenzylidene) benzothiophene-2-carbohydrazide
Authors: Naganagowda Gadada , Petsom Amorn
Published: September 2011

The title compound, 3-chloro-N'-(2-hydroxy-4-pentadecylbenzylidene)­benzo[b]thiophene-2-carbohydrazide has been synthesized by reaction of 2-hydroxy-4-pentadecylbenzaldehyde with 3-chloro-1-benzo[b]thiophene-2-carboxylic acid hydrazide in the presence of acetic acid in ethanol. The structure of this new compound was confirmed by elemental analysis, IR, 1H-NMR, 13C-NMR and mass spectral analysis.
Thermal and Rheological Properties of a Family of Botryosphaerans Produced by Botryosphaeria rhodina MAMB-05
Authors: Fonseca Paulo R.M.S. , Dekker Robert F.H. , Barbosa Aneli M. , Silveira Joana L.M. , Vasconcelos Ana F.D. , Monteiro Nilson K. , Aranda-Selverio Gabriel , Da Silva Maria de Lourdes Corradi
Published: September 2011

Differential scanning calorimetry (DSC), thermogravimetry (TG) and Fourier-transform infra-red spectroscopy (FT-IR) analyses were performed to investigate changes in the physico-chemical properties of botryosphaerans, a family of exopolysaccharides (EPS) produced by the fungus Botryosphaeria rhodina MAMB-05 grown on glucose (EPSGLC), sucrose (EPSSUC) and fructose (EPSFRU). A slight endothermic transition and small mass loss attributable to the removal of water of hydration were observed in the DSC and TG analyses, respectively, for the three EPS samples. The FT-IR spectra confirmed no structural changes occurred during thermal treatment. Viscometry was utilized to obtain information on the rheological behaviour of the EPS in aqueous solutions. The Power Law and Cross Equations determined the natural pseudoplastic characteristics of the EPS. Comparatively, results obtained for EPS produced when B. rhodina MAMB-05 was grown on each of the three carbohydrate sources demonstrated similar apparent viscosity values for EPSGLC and EPSSUC, while EPSFRU displayed the lowest apparent viscosity of the three botryosphaerans, suggesting a higher degree of ramification and lower Mw. EPSGLC and EPSSUC possessed similar degrees of ramification. The slight differences found in their viscosities can be explained by the differences in the type of branching among the three botryosphaerans, thus varying the strength of intermolecular interactions and consequently, consistency and viscosity. The physico-chemical studies of botryosphaerans represent the originality of this work, and the knowledge of these properties is an important criterion for potential applications.
In Silico Veritas: The Pitfalls and Challenges of Predicting GPCR-Ligand Interactions
Authors: Roumen Luc , Sanders Marijn P.A. , Vroling Bas , De Esch Iwan J.P. , De Vlieg Jacob , Leurs Rob , Klomp Jan P.G. , Nabuurs Sander B. , De Graaf Chris
Published: September 2011

Recently the first community-wide assessments of the prediction of the structures of complexes between proteins and small molecule ligands have been reported in the so-called GPCR Dock 2008 and 2010 assessments. In the current review we discuss the different steps along the protein-ligand modeling workflow by critically analyzing the modeling strategies we used to predict the structures of protein-ligand complexes we submitted to the recent GPCR Dock 2010 challenge. These representative test cases, focusing on the pharmaceutically relevant G Protein-Coupled Receptors, are used to demonstrate the strengths and challenges of the different modeling methods. Our analysis indicates that the proper performance of the sequence alignment, introduction of structural adjustments guided by experimental data, and the usage of experimental data to identify protein-ligand interactions are critical steps in the protein-ligand modeling protocol.
Photomechanical Response of Composite Structures Built from Azobenzene Liquid Crystal Polymer Networks
Authors: Lee Kyung Min , White Timothy J.
Published: September 2011

Optically directed shape adaptive responses have been sought after for many decades in photoresponsive polymeric materials. A number of recent examinations have elucidated elucidated the unique opportunities of photomechanical responses realized in azobenzene-functionalized liquid crystalline polymer networks (both elastomers and glasses). This work summarizes and contrasts the photomechanical response of glassy polydomain, monodomain, and twisted nematic azo-LCN materials to blue-green irradiation. Building from this summary, the combinatorial photomechanical response observed upon irradiation of composite cantilevers is examined. Large scale shape adaptations are realized, with novel responses that may be of potential use in future employment of these materials in actuation.
A Multi-Resolution Multi-Temporal Technique for Detecting and Mapping Deforestation in the Brazilian Amazon Rainforest
Authors: Arai Egídio , Shimabukuro Yosio E. , Pereira Gabriel , Vijaykumar Nandamudi L.
Published: September 2011

The analysis of rapid environment changes requires orbital sensors with high frequency of data acquisition to minimize cloud interference in the study of dynamic processes such as Amazon tropical deforestation. Moreover, a medium to high spatial resolution data is required due to the nature and complexity of variables involved in the process. In this paper we describe a multiresolution multitemporal technique to simulate Landsat 7 Enhanced Thematic Mapper Plus (ETM+) image using Terra Moderate Resolution Imaging Spectroradiometer (MODIS). The proposed method preserves the spectral resolution and increases the spatial resolution for mapping Amazon Rainfores deforestation using low computational resources. To evaluate this technique, sample images were acquired in the Amazon rainforest border (MODIS tile H12-V10 and ETM+/Landsat 7 path 227 row 68) for 17 July 2002 and 05 October 2002. The MODIS-based simulated ETM+ and the corresponding original ETM+ images were compared through a linear regression method. Additionally, the bootstrap technique was used to calculate the confidence interval for the model to estimate and to perform a sensibility analysis. Moreover, a Linear Spectral Mixing Model, which is the technique used for deforestation mapping in Program for Deforestation Assessment in the Brazilian Legal Amazonia (PRODES) developed by National Institute for Space Research (INPE), was applied to analyze the differences in deforestation estimates. The results showed high correlations, with values between 0.70 and 0.94 (p < 0.05, student’s t test) for all ETM+ bands, indicating a good assessment between simulated and observed data (p < 0.05, Z-test). Moreover, simulated image showed a good agreement with a reference image, originating commission errors of 1% of total area estimated as deforestation in a sample area test. Furthermore, approximately 6% or 70 km² of deforestation areas were missing in simulated image classification. Therefore, the use of Landsat simulated image provides better deforestation estimation than MODIS alone.
ICESat/GLAS Data as a Measurement Tool for Peatland Topography and Peat Swamp Forest Biomass in Kalimantan, Indonesia
Authors: Ballhorn Uwe , Jubanski Juilson , Siegert Florian
Published: September 2011

Indonesian peatlands are one of the largest near-surface pools of terrestrial organic carbon. Persistent logging, drainage and recurrent fires lead to huge emission of carbon each year. Since tropical peatlands are highly inaccessible, few measurements on peat depth and forest biomass are available. We assessed the applicability of quality filtered ICESat/GLAS (a spaceborne LiDAR system) data to measure peatland topography as a proxy for peat volume and to estimate peat swamp forest Above Ground Biomass (AGB) in a thoroughly investigated study site in Central Kalimantan, Indonesia. Mean Shuttle Radar Topography Mission (SRTM) elevation was correlated to the corresponding ICESat/GLAS elevation. The best results were obtained from the waveform centroid (R2 = 0.92; n = 4,186). ICESat/GLAS terrain elevation was correlated to three 3D peatland elevation models derived from SRTM data (R2 = 0.90; overall difference = −1.0 m, ±3.2 m; n = 4,045). Based on the correlation of in situ peat swamp forest AGB and airborne LiDAR data (R2 = 0.75, n = 36) an ICESat/GLAS AGB prediction model was developed (R2 = 0.61, n = 35). These results demonstrate that ICESat/GLAS data can be used to measure peat topography and to collect large numbers of forest biomass samples in remote and highly inaccessible peatland forests.
Demonstration of Two Portable Scanning LiDAR Systems Flown at Low-Altitude for Investigating Coastal Sea Surface Topography
Authors: Vrbancich Julian , Lieff Wolfgang , Hacker Jorg
Published: September 2011

We demonstrate the efficacy of a commercial portable 2D laser scanner (operating at a wavelength close to 1,000 nm) deployed from a fixed-wing aircraft for measuring the sea surface topography and wave profiles over coastal waters. The LiDAR instrumentation enabled simultaneous measurements of the 2D laser scanner with two independent inertial navigation units, and also simultaneous measurements with a more advanced 2D laser scanner (operating at a wavelength near 1,500 nm). The latter scanner is used routinely for accurately measuring terrestrial topography and was used as a benchmark in this study. We present examples of sea surface topography and wave profiles based on low altitude surveys (< ~300 m) over coastal waters in the vicinity of Cape de Couedic, Kangaroo Island, South Australia and over the surf zone adjacent to the mouth of the Murray River, South Australia. Relative wave heights in the former survey are shown to be consistent with relative wave heights observed from a waverider buoy located near Cape de Couedic during the LiDAR survey. The sea surface topography of waves in the surf zone was successfully mapped with both laser scanners resolving relative wave height variations and fine structure of the sea surface to within approximately 10 cm. A topographic map of the sea surface referenced to the airborne sensor frame transforms to an accurate altimetry map which may be used with airborne electromagnetic instrumentation to provide an averaged altimetry covering a portion of the larger electromagnetic footprint. This averaged altimetry is deemed to be significantly more reliable as a measurement of altimetry than spot measurements using a nadir-looking laser altimeter and would therefore improve upon the use of airborne electromagnetic methods for bathymetric mapping in surf-zone waters. The aperture range of the scanner does not necessarily determine the swath. We observed that instead, the maximum swath at a given altitude was limited by the angle of incidence of the laser at the water surface.
Restitution of Sculptural Groups Using 3D Scanners
Authors: Merchán Pilar , Salamanca Santiago , Adán Antonio
Published: September 2011

Imagine for a moment that you have to solve a 3D jigsaw of which you have lost several pieces. You have also lost the original box-top showing the final picture, and as if that were not enough, some of the pieces you do have may belong to some other jigsaw. This is in essence the sort of challenge that we faced in the novel project that we shall be describing in this paper. The final aim of the project was, with the help of 3D scanners, to digitalize and reconstruct multi-piece classical sculptures. Particularly, we tackle the restitution of the so-called “Aeneas Group”, a famous iconographic reference during the Roman Empire. We have undertaken this ambitious project in collaboration with the research department of the Spanish National Museum of Roman Art (MNAR). This paper summarizes the real problems that arose and had to be solved, the innovations, and the main results of the work that we have carried out over these recent years.
Design and Implementation of an Underwater Sound Recording Device
Authors: Martinez Jayson J. , Myers Josh R. , Carlson Thomas J. , Deng Z. Daniel , Rohrer John S. , Caviggia Kurt A. , Woodley Christa M. , Weiland Mark A.
Published: September 2011

To monitor the underwater sound and pressure waves generated by anthropogenic activities such as underwater blasting and pile driving, an autonomous system was designed to record underwater acoustic signals. The underwater sound recording device (USR) allows for connections of two hydrophones or other dynamic pressure sensors, filters high frequency noise out of the collected signals, has a gain that can be independently set for each sensor, and allows for 2 h of data collection. Two versions of the USR were created: a submersible model deployable to a maximum depth of 300 m, and a watertight but not fully submersible model. Tests were performed on the USR in the laboratory using a data acquisition system to send single-frequency sinusoidal voltages directly to each component. These tests verified that the device operates as designed and performs as well as larger commercially available data acquisition systems, which are not suited for field use. On average, the designed gain values differed from the actual measured gain values by about 0.35 dB. A prototype of the device was used in a case study to measure blast pressures while investigating the effect of underwater rock blasting on juvenile Chinook salmon and rainbow trout. In the case study, maximum positive pressure from the blast was found to be significantly correlated with frequency of injury for individual fish. The case study also demonstrated that the device withstood operation in harsh environments, making it a valuable tool for collecting field measurements.
Angle Estimation of Simultaneous Orthogonal Rotations from 3D Gyroscope Measurements
Authors: Stančin Sara , Tomažič Sašo
Published: September 2011

A 3D gyroscope provides measurements of angular velocities around its three intrinsic orthogonal axes, enabling angular orientation estimation. Because the measured angular velocities represent simultaneous rotations, it is not appropriate to consider them sequentially. Rotations in general are not commutative, and each possible rotation sequence has a different resulting angular orientation. None of these angular orientations is the correct simultaneous rotation result. However, every angular orientation can be represented by a single rotation. This paper presents an analytic derivation of the axis and angle of the single rotation equivalent to three simultaneous rotations around orthogonal axes when the measured angular velocities or their proportions are approximately constant. Based on the resulting expressions, a vector called the simultaneous orthogonal rotations angle (SORA) is defined, with components equal to the angles of three simultaneous rotations around coordinate system axes. The orientation and magnitude of this vector are equal to the equivalent single rotation axis and angle, respectively. As long as the orientation of the actual rotation axis is constant, given the SORA, the angular orientation of a rigid body can be calculated in a single step, thus making it possible to avoid computing the iterative infinitesimal rotation approximation. The performed test measurements confirm the validity of the SORA concept. SORA is simple and well-suited for use in the real-time calculation of angular orientation based on angular velocity measurements derived using a gyroscope. Moreover, because of its demonstrated simplicity, SORA can also be used in general angular orientation notation.
Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors
Authors: Wang Wei-Song , Huang Hong-Yi , Chen Shu-Chun , Ho Kuo-Chuan , Lin Chia-Yu , Chou Tse-Chuan , Hu Chih-Hsien , Wang Wen-Fong , Wu Cheng-Feng , Luo Ching-Hsing
Published: September 2011

A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC), a microcontroller unit (MCU), a graphical user interface (GUI), and a radio frequency (RF) transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA) to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA). The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR) greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment), a small size of 5.6 cm × 8.7 cm, high portability, and high integration.
Symmetry, Invariance and Ontology in Physics and Statistics
Authors: Stern Julio Michael
Published: September 2011

This paper has three main objectives: (a) Discuss the formal analogy between some important symmetry-invariance arguments used in physics, probability and statistics. Specifically, we will focus on Noether’s theorem in physics, the maximum entropy principle in probability theory, and de Finetti-type theorems in Bayesian statistics; (b) Discuss the epistemological and ontological implications of these theorems, as they are interpreted in physics and statistics. Specifically, we will focus on the positivist (in physics) or subjective (in statistics) interpretations vs. objective interpretations that are suggested by symmetry and invariance arguments; (c) Introduce the cognitive constructivism epistemological framework as a solution that overcomes the realism-subjectivism dilemma and its pitfalls. The work of the physicist and philosopher Max Born will be particularly important in our discussion.
Dengue — Quo tu et quo vadis?
Authors: Chen Rubing , Vasilakis Nikos
Published: September 2011

Dengue viruses (DENV) are by far the most important arboviral pathogens in the tropics around the world, putting at risk of infection nearly a third of the global human population. DENV are members of the genus Flavivirus in the Family Flaviviridae and comprise four antigenically distinct serotypes (DENV-1-4). Although they share almost identical epidemiological features, they are genetically distinct. Phylogenetic analyses have revealed valuable insights into the origins, epidemiology and the forces that shape DENV evolution in nature. In this review, we examine the current status of DENV evolution, including but not limited to rates of evolution, selection pressures, population sizes and evolutionary constraints, and we discuss how these factors influence transmission, pathogenesis and emergence.
Special Issue: Viruses Infecting Fish, Amphibians, and Reptiles
Authors: Chinchar V. Gregory
Published: September 2011

Although viruses infecting and affecting humans are the focus of considerable research effort, viruses that target other animal species, including cold-blooded vertebrates, are receiving increased attention. In part this reflects the interests of comparative virologists, but increasingly it is based on the impact that many viruses have on ecologically and commercially important animals. Frogs and other amphibians are sentinels of environmental health and their disappearance following viral or fungal (chytrid) infection is a cause for alarm. Likewise, because aquaculture and mariculture are providing an increasingly large percentage of the “seafood” consumed by humans, viral agents that adversely impact the harvest of cultured fish and amphibians are of equal concern. [...]
Structure par terme des taux d'intérêt, volatilité et primes de risque : applications au marché de l'Eurolire
Authors: Drudi Francesco , Violi Roberto
Published: September 2011

The Term Structure of Interest Rates, Volatility and Risk Premia : Applications to the Eurolira

Market by Francesco Drudi and Roberto Violi

This paper studies the information content of the term structure of interest rates on the Eurolira market. By estimating a single-factor equilibrium model of the term structure (Cox, Ingersoll and Ross, 1985), we derive measures of expectations, volatility and risk premia embodied in nominal interest rates and option prices. We provide econometric evidence indicating that Eurolira nominal interest rates display (near) unit-root behaviour. This property also extends to spreads between short and long rates. (Near) unit-roots have far-reaching implications as regards estimating parameters for factor models of the term structure. The quality of such estimates is crucial to measuring risk-premia and volatility and especially to assessing the empirical validity of the Expectations Hypothesis of the Term Structure (EHTS). Empirical tests suggest that the size and volatility of risk premia observed on the Eurolira market are substantial enough to warrant rejecting the EHTS.
Changements structurels de la prime de risque et évaluation des marchés d'actions
Authors: Bruneau Catherine , Duval-Kieffer Ch. , Nicolaï Jean-Paul
Published: September 2011

Changes in Structural Risk Premiums and Assessment of Stock Markets by Catherine Bruneau, Ch. Duval-Kieffer and Jean-Paul Nicola'i

In this paper, we estimate a fundamental value of the S&P index, which we use as a long-run target in an error-correction modelling of the dynamics of the subsequent returns. The Gordon-Shapiro-based Present Value Model suggests two fundamentals: dividends and a discount rate factor, specified as a risk-free rate plus an ex-ante risk premium, modelled as successive structural breaks at predetermined dates assumed to affect agents' expectations. These breaks are introduced into the cointégration relationship as dummies to ensure the stationarity of the equilibrium deviation variable and the significance of the error correction term. Consequently, the prices observed only move temporarily away from their fundamental value. We use Monte-Carlo simulations to compute the relevant critical values for the stationarity tests. The dates of the breaks over the study period are then related to changes in the stock pricing process.
Facteurs de risque communs sur les marchés internationaux d'actions, d'obligations et de changes
Authors: De Bandt Olivier
Published: September 2011

Common Risk Factors on the International Stock, Bond and Exchange Markets

by Olivier De Bandt

This paper finds a «predictability» of yield spreads on the stock, bond and exchange markets in the United States, Japan, Germany and the United Kingdom for the 1980: 1-1994:5 period. Although this property is more significant on the bond and exchange markets than on the stock market, it can be used for a dynamic measurement of financial market integration. We find common risk factors among these three assets at national level. We moreover find a close international integration of the bond markets, which also feature common risk factors: the yield premium on the two different countries' bond markets and that on the exchange market are generally well represented by a model with two latent variables. Nevertheless, these relationships appear to be unstable over time.
Coopération monétaire en Asie de l'Est : l'apport des tests de causalité et de la cointégration
Authors: Fukasaku Kiichiro , Martineau David
Published: September 2011

Coopération monétaire en Asie de l'Est : l'apport des tests de causalité et de la cointégration

par Kiichiro Fukasaku et David Martineau

Dans cet article, nous examinons les politiques monétaires des économies de l'Asie de l'Est à la suite de la libéralisation des marchés monétaires sur la période 1980-95. Nous discutons des conditions d'une coopération monétaire dans cet espace monétaire nouvellement "libéralisé". À l'aide de tests de causalité et d'estimations des fonctions de demandes de monnaie par la méthode de la cointégration, nous démontrons que les marchés monétaires de la région ont aujourd'hui atteints un fort niveau d'intégration. Enfin, nous montrons que la politique monétaire de Singapour est un élément clef de l'explication du niveau des taux d'intérêt et de la demande de monnaie des pays voisins sur cette période.
Composantes permanente et transitoire de l'épargne et de l'investissement : une étude empirique des flux internationaux de capitaux au Japon
Authors: Girardin Eric , Sarno Lucio , Taylor Mark P.
Published: September 2011

Transitory and permanent components of saving and investment: an empirical study of

international capital flows in Japan by Eric Girardin, Lucio Sarno and Mark P. Taylor

This paper presents an empirical study of the difference between the short- and the long-run saving-investment correlation coefficient using quarterly Japanese data, in an attempt to shed light both on the Feldstein-Horioka regression's validity in quantifying the degree of international capital mobility and on its implications. We also empirically assess the effectiveness of the abolition of exchange controls, which removed all restrictions on capital flows between Japan and the international economy in 1980. Consistent with our economic intuition and the logical consequences of the Feldstein-Horioka interpretation, our results suggest that the short-run saving-investment association is significantly stronger than the corresponding long-run association and, in contrast with much of the relevant empirical literature, Japan appears to have been highly financially integrated into the global economy since 1980. pital flows ; transitory and permanent components ; Kalman filter.
Crises financières, stratégie d'investissement dans les pays à risque, comportement des investisseurs
Authors: Artus Patrick
Published: September 2011

Financial Crises, Investment Strategy in High-Risk Countries and Investor Behaviour

by Patrick Artus

We examine the dynamics of exchange-rate expectations, foreign exchange reserves and foreign investor assets in a country with a serious macroeconomic imbalance (excessive inflation) applying a fixed exchange-rate system. We use a model that generalises those used to study balance of payments crises.

We compare the development of foreign investor assets over time and especially the dynamics of withdrawal from this high-risk country by both individual risk-averse investors and investment funds competing for market shares in financial savings. We consider whether investment funds withdraw from high-risk countries later and more suddenly than individual investors, which would correspond to the observed facts (e.g. the Mexican crisis).
Le Franc français et la récente crise monétaire européenne
Authors: Jona-Lasinio Cécilia
Published: September 2011

The French Franc and the Recent European Currency Crisis by Cecilia Jona-Lasinio

The 1992 and 1993 currency crises demonstrated the enormous pressures that can be raised against official exchange rate parities when investors perceive that significant exchange rate realignments may be imminent. In this paper I propose an empirical analysis of the 1 992- 1 993 crises to establish whether speculators were able to perceive the exact timing of the devaluations and if and how the economic and political news influenced their devaluation expectations. In particular, I analyse the expected timing of devaluation of the French Franc relative to the Deutschemark before the 1 992 and 1 993 currency crisis. The empirical analysis shows that before the occurrence of both crisis agents were awareof the imminence of the devaluation and that they were very sensitive to the news spread daily over the markets.
Programmation mathématique positive et offre de céréales et d'oléagineux dans l'Union Européenne sous l'agenda 2000
Authors: Barkaoui Ahmed , Butault Jean-Pierre
Published: September 2011

Positive Mathematical Programming and Cereal and Oilseed Supply in the European Union Under Agenda 2000 by Ahmed Barkaoui and Jean-Pierre Butault

In this study, we simulate the effect that Agenda 2000' s CAP reform projects will have on the EU field crop supply by 2005. We apply the Positive Mathematical Programming method at regional level in twelve EU Member States. Simulations are based on the 1994 Community FADN database. Our forecasts show that cereal production will increase sharply and oilseed production will decrease over the period from 1994*to 2005. These results will have a considerable effect on market equilibrium.
Les transferts versés aux enfants et aux parents : altruisme ou échange intertemporel?
Authors: Wolff François-Charles
Published: September 2011

Transfers Paid to Children and Parents : Altruism or Intertemporal Exchange ?

by François-Charles Wolff

This article studies family transfers paid by an intermediate generation (pivot) to its adult children and parents. This solicitation from both sides may be explained by an intertemporal exchange, whereby selfish pivots lend money to the young to be paid back later. Conversely, it may be explained by the pivots' altruism towards their children and parents. An econometric analysis based on the 1992 CNAV Three Generations survey reveals that financial assistance to children is mainly an investment in human capital and that assistance to ascendants is mainly determined by the needs of the assisted parents. Although this assistance hardly reflects a contractual reimbursement by the pivots, the altruistic model is also rejected by the data.
De l'antisélection à la sélection en assurance santé : pour un changement de perspective
Authors: Couffinhal Agnès
Published: September 2011

Un des arguments couramment évoqués pour justifier l'intervention de l'État dans l'assurance maladie est la présence d' antisélection. Toutefois, l'analyse économique, dans la lignée du modèle de Rothschild et Stiglitz (1976), montre que les assureurs peuvent parvenir à surmonter l'asymétrie d'information dont ils sont victimes en différenciant les contrats. Rappeler les principaux résultats de cette recherche permet de dégager les conditions nécessaires à une validation empirique de l'antisélection et de présenter les tests visant à établir si elle est constituée sur les marchés d'assurance santé. Au terme de ce travail, on ne peut rejeter l'hypothèse selon laquelle l'antisélection est présente sur les marchés d'assurance santé ; en revanche, l'ampleur du phénomène ne semble pas très forte. Il apparaît de plus que l'antisélection n'est qu'une des limites au fonctionnement efficace des marchés d'assurance et la différenciation des contrats une des réponses possibles de l'assureur. La sélection des risques par les assureurs eux-mêmes est un autre phénomène, souvent confondu avec l'antisélection, lui aussi dommageable au fonctionnement du marché. Clarifier l'articulation entre antisélection et sélection conduit à souligner la nécessité de mieux prendre en compte ce second phénomène dans une analyse du fonctionnement du marché.
Dépenses de santé : l'hypothèse d'aléa moral
Authors: Geoffard Pierre-Yves
Published: September 2011

Health Expenditures : the Moral Hazard Assumption by Pierre- Yves Geoffard

The analysis of many proposals to reform the French health insurance system, and in particular those focusing on co-payment schemes, is heavily dependent on delicate empirical measures of the elasticity of demand for health care.

This paper offers a critical survey of the empirical literature on the moral hazard assumption, according to which

more extensive health insurance coverage would lead to more spending.

The paper begins by recalling that the Rand Health Insurance Study, a major study conducted in the United States in

the 1970s, unambiguously concluded that the price elasticity of demand for medical care was negative, especially

for ambulatory care. The paper then stresses the limitations of more recent studies undertaken on French data -

limitations which are either inherent to the data or due to the econometric methods employed. In addition,

evaluating the redistributive aspects of co-payments and their impact on access to care would require more accurate

measures of cross price-income elasticity.

Despite all these uncertainties, the lessons drawn from the existing empirical studies suggest that the current French

co-payment scheme (the ticket modérateur system) is very far from being fair and efficient.
Induction de la demande de soins par les médecins libéraux français. Étude micro-économétrique sur données de panel
Authors: Delattre Eric , Dormont Brigitte
Published: September 2011

Cette étude a pour objet d'analyser les comportements d'offre de soins des médecins libéraux français. On dispose pour cela d'un panel non cylindre de 7 925 médecins omnipraticiens ou spécialistes, des secteurs 1 ou 2, suivis sur la période 1979-1993 et représentatif de la population concernée. Les estimations mettent en évidence l'existence de comportements de demande induite indéniables dans le secteur 1 . Ces comportements permettent aux médecins de limiter les rationnements qu'ils subissent sur le nombre de rencontres médecin-patient quand la densité médicale augmente, et de les compenser par une augmentation du volume de soins fournis au cours de chaque rencontre. Dans le secteur 2 (à honoraires libres), la réaction des médecins aux variations de la densité est compatible avec une absence de comportements d'induction. En effet, une élévation de la densité médicale conduit dans ce secteur à une baisse des tarifs et à une augmentation de l'activité, réactions conformes aux prédictions d'un modèle d'offre de soins basé sur l'hypothèse de concurrence monopolistique. Au total, on constate qu'une augmentation de la densité entraîne une hausse des quantités de soins fournies dans les deux secteurs. En outre, les baisses de tarifs observées dans le secteur 2 ne contribuent pas à un rééquilibrage des comptes sociaux, puisqu'elles ne concernent que les dépassements. Enfin, nos évaluations permettent d'établir que les élasticités estimées au niveau microéconomique correspondent, au niveau macroéconomique, à une forte dérive de la consommation de soins en liaison avec l'augmentation du nombre de médecins.
Comportements opportunistes des patients et des médecins : l'apport d'analyses par épisode de soins
Authors: Breuil-Genier Pascale , Rupprecht Frédéric
Published: September 2011

Opportunistic Behaviour of Patients and Doctors: the Contribution of Analyses by Health Care Episode by Pascale Breuil-Genier and Frédéric Rupprecht

The "strategic" behaviours attributed to patients (adverse selection, moral hazard) and health care professionals (supply-induced demand) are not easily tested: although it is easy to find a link between health insurance and health care consumption, it is more difficult to single out the behavioural consequences of moral hazard and adverse selection. Similarly, a simultaneous increase in doctor density and in health care consumption may indeed be a consequence of induced demand (whereby doctors create the demand for their own services), but it may also result from an exogenous rise in health care needs combined with a simultaneous rise in the resources required to meet them. In an attempt to identify the determinants of patients' and doctors' behaviour more precisely, we analyse the series of consumption decisions taken for a given illness and a given patient by reconstructing health care episodes from the 1 99 1 -92 health survey. Our analysis shows that a patient' s decision to seek health care in case of sickness is strongly influenced by whether the patient possesses supplementary insurance coverage, but that this factor has no impact on the choice of the type of first consultation (general practitioner or specialist), nor on whether the patient subsequently seeks other consultations. The doctor density explains part of the choice between general practitioners and specialists for the initial consultation, but this variable has no impact on the number of first consultations, nor on whether the patient subsequently seeks other consultations.
Les méthodes du bootstrap dans les modèles de régression
Authors: Flachaire Emmanuel
Published: September 2011

Bootstrap Methods in Regression Models by Emmanuel Flachaire

In practice, we rarely know the true probability distribution of a test statistic and we generally base tests on its asymptotic distribution. If the sample size is not large enough, the asymptotic distribution could be a poor approximation of the true distribution. Consequently, tests based on it could be largely biased. Bootstrap methods yield a more accurate approximation of the distribution of a test statistic than the approximation obtained from the first-order asymptotic theory. Moreover, they provide a way of substituting computation for mathematical analysis when it proves hard to calculate the asymptotic distribution of an estimator or statistic. In this paper, we present a general methodology of the bootstrap in regression models.
Instruments économiques dans la perspective du changement climatique
Authors: Henry Claude , Tubiana Laurence
Published: September 2011

Economic Instruments for Climate Change by Claude Henry and Laurence Tubiana

The 1997 Kyoto commitments to reduce greenhouse gas emissions are not enough to contend with the threats of climate change. Yet they already place such constraints on the European Union and the United States that they may well be renounced if they are not implemented with the greatest economic efficiency. This is only possible if instruments are mobilised to flexibly, but rigorously, implement these reductions at the lowest possible overall cost by more or less balancing out the different emitters' marginal reduction costs.

In this paper, we study the various instruments - especially emissions trading - addressed by the international negotiations and how they are interlinked. Since the developing countries will gradually rank among the leading emitting countries, it is vital that they play a fully-fledged part in the efficient implementation of the instruments. Yet such participation is only feasible if the conditions of equity in the initial permit distribution (i.e. before trading) are satisfied. These conditions were overlooked in Kyoto, but are a core issue in the current negotiations, especially for The Hague in November 2000.
Honnêteté et conformité environnementale
Authors: Bontems Philippe , Rotillon Gilles
Published: September 2011

Integrity and Environmental Compliance by Philippe Bontems and Gilles Rotillon

We here study how the existence of conscientious attitudes affects the working of compliance between an environmental agency and polluting firms, where the supervision policy may or may not include firms' self-reporting of discharges. Two main findings have been made. Firstly, non-interference may be the best policy for the agency if there is a high enough proportion of conscientious firms. Secondly, contrary to what we might expect, an exogenous increase in the number of conscientious firms does not necessarily lead to a decrease in pollution. We show that it is in fact possible that, given the number of conscientious firms, the optimum probability of inspection is low enough to entail a growth in fraud and therefore pollution. Moreover, with the system of self-reporting, which is the optimum option, an increase in the number of conscientious firms may also in some cases involve an increase in the total cost of inspection and, ultimately, welfare losses.
Dynamique de la consommation d'eau potable des ménages : une étude sur un panel de communes françaises
Authors: Nauges Céline , Thomas Alban
Published: September 2011

Dynamics of Household Drinking- Water Consumption: Study of a Sample Group of French

Communes

by Cécile Nauges and Alban Thomas

The early 1990s was a turning point for household consumption of water. In addition to a surge in price, a decline in domestic consumption was recorded for the first time. This paper demonstrates that users were not unresponsive to the increase in the price of water, since long-term elasticity is calculated to be -0.6 over the 1988-1993 period. Moreover, estimation from a dynamic model with non-stationary individual effects reveals the influence of specific phenomena in 1990 and 1991. The droughts during this period and the discussion on the entry into force of new regulations unquestionably raised the awareness of consumers, who altered their consumption behaviour.
Ressources naturelles et croissance endogène dans un modèle à biens horizontalement différenciés
Authors: Grimaud André
Published: September 2011

Natural Resources and Endogenous Growth in a Horizontally Differentiated Goods Model

by André Grimaud

A number of authors such as P. Shou, P. Aghion and P. Howitt have defined optimal growth paths in a Schumpeterian model with non-renewable resources. The main aim of this paper is to show how these optimal paths can be applied in a decentralized economy. We also analyse the effects of intervention instruments on the economy's long-run trends, especially the product growth rate and the rate of resource extraction.
Le traitement des réponses égales à zéro dans l'évaluation contingente
Authors: Ami Dominique , Desaigues Brigitte
Published: September 2011

L'évaluation contingente est couramment utilisée pour donner un prix aux actifs naturels. Le traitement économétrique des valeurs obtenues à l'aide de cette méthode directe de révélation des préférences pose des problèmes du fait du nombre élevé (généralement autour de 50%) de valeurs nulles. Différentes méthodes de traitement des réponses égales à zéro, dans le cas d'une question ouverte, peuvent être envisagées. Trois modèles sont étudiés, testés économétriquement et comparés : le modèle de régression linéaire, le modèle de Heckman et le modèle de Tobin. On s'interroge également sur les comportements micro-économiques sous-jacents à chacun de ces modèles. L'objectif de cet article est de montrer qu'il n'est pas pertinent d'utiliser le modèle de Tobin car les valeurs nulles ne peuvent pas être traitées uniformément comme des valeurs censurées.
Révélation du CAP : question ouverte ou question fermée ? Une application à la biodiversité des forêts riveraines de la Garonne
Authors: Gauthier Caroline
Published: September 2011

WTP Revelation: Open-Ended or Dichotomous-Choice Questions? An Application to the

Biodiversity of the Garonne River Forests

by Caroline Gauthier

This paper offers a contingent valuation of individuals' willingness to pay for preservation of biodiversity. It is the first study of its kind to be carried out in France. It has been conducted according to the rules proposed by the NOAA Panel, with the exception of the revelation method. The sample of 402 individuals interviewed was divided into those who declared their WTP on the basis of an open-ended question and those who declared it on the basis of a dichotomous-choice question. The two formats were then compared. The paper offers two tests demonstrating that the WTPs calculated by each method are not significantly different. Although the NOAA Panel recommends use of the closed format, this paper shows that use of the open-ended question is equally relevant and less expensive given the level of information required.
Une évaluation économique des bénéfices de morbidité bénigne induits par une amélioration de la qualité de l'air
Authors: Rozan Anne
Published: September 2011

An Economic Valuation of the Morbidity Benefits Induced by an Improvement in Air Quality

by Anne Rozan

From the public decision-maker's point of view, a policy combating air pollution is justified if the benefits generated are greater than the costs. Most studies value the benefits of improved air quality in terms of avoided health costs, thus disregarding annoyance and self-treatment. Our study offers an estimation of morbidity benefits using the contingent valuation method. Not only does morbidity affect the whole population, but it is also the most frequent health effect of air pollution. However, a cost-based method underestimates these benefits. The study was conducted on a representative sample of the residents of Strasbourg.
L'influence de la diffusion et de la différenciation des produits sur la dynamique des parts de marché : une application au marché français des semences de maïs
Authors: Lemarié Stéphane
Published: September 2011

L'influence de la diffusion et de la différenciation des produits sur la dynamique des parts de marché : une application au marché français des semences de maïs

par Stéphane Lemarié

Les analyses empiriques sur les marchés différenciés connaissent un essor important depuis dix ans. À partir d'un modèle simple en forme réduite, nous mettons en évidence différents facteurs significatifs qui n'avaient pas été mis en évidence jusque là : l'effet de l'âge du produit pendant les premières périodes de diffusion, l'effet d'un accident technique sur le produit, l'effet de la taille de l'entreprise qui propose le produit. Le modèle est appliqué au marché français des semences de maïs pour l'ensemble de la période 1976-1994.
Fonction de demande et surplus : une estimation sur des données de panel pour les transports urbains français
Authors: Croissant Yves
Published: September 2011

Fonction de demande et surplus : une estimation sur des données de panel pour les transports

urbains français par Yves Croissant

Cet article présente l'estimation d'une fonction de demande pour les transports urbains. Il s'agit d'une fonction de type translog qui prend en compte la distribution des revenus et qui est estimée sur données de panel françaises. Les élasticités par rapport au prix et à la qualité sont conformes à celles obtenues habituellement. L'intérêt d'utiliser une forme flexible est de pouvoir construire par intégration de la demande une fonction de surplus.