bluuebunny/crossref_metadata_2025 huggingface dataset:
Silibinin Causes Apoptosis and Cell Cycle Arrest in Some Human Pancreatic Cancer Cells
Authors: Ge Yakun , Zhang Yuanxin , Chen Yunpeng , Li Quanshun , Chen Jun , Dong Ying , Shi Wei
Published: August 2011

Silibinin, an effective anti-cancer and chemopreventive agent in various epithelial cancer models, has been reported to inhibit cancer cell growth through mitogenic signaling pathways. However, whether it can inhibit human pancreatic carcinoma growth and what are the underlying mechanisms is still not well elucidated. Here, we evaluated the inhibitory proliferation effects of Silibinin in pancreatic carcinoma growth and examined whether Silibinin modulates cell cycle and apoptosis. Our results indicate that Silibinin effectively inhibited the pancreatic carcinoma AsPC-1, BxPC-3 and Panc-1 cells’ proliferation and caused apoptosis. Silibinin induced a decrease in S phase and cell cycle arrest in G1 phase in AsPC-1 cells, but had no obvious changes in BxPC-3 and Panc-1 cell cycle. Furthermore, these results suggest that Silibinin might be a candidate chemopreventive agent for pancreatic carcinoma therapy.
The Chemical Composition and Nitrogen Distribution of Chinese Yak (Maiwa) Milk
Authors: Li Haimei , Ma Ying , Li Qiming , Wang Jiaqi , Cheng Jinju , Xue Jun , Shi John
Published: August 2011

The paper surveyed the chemical composition and nitrogen distribution of Maiwa yak milk, and compared the results with reference composition of cow milk. Compared to cow milk, yak milk was richer in protein (especially whey protein), essential amino acids, fat, lactose and minerals (except phosphorus). The contents of some nutrients (total protein, lactose, essential amino acids and casein) were higher in the warm season than in the cold season. Higher ratios of total essential amino acids/total amino acids (TEAA/TAA) and total essential amino acids/total non essential amino acids (TEAA/TNEAA) were found in the yak milk from the warm season. However its annual average ratio of EAA/TAA and that of EAA/NEAA were similar to those of cow milk. Yak milk was rich in calcium and iron (p < 0.05), and thus may serve as a nutritional ingredient with a potential application in industrial processing.
ZnS, CdS and HgS Nanoparticles via Alkyl-Phenyl Dithiocarbamate Complexes as Single Source Precursors
Authors: Onwudiwe Damian C. , Ajibade Peter A.
Published: August 2011

The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm), 2.91 eV (426 nm) and 4.27 eV (290 nm) for the ZnS, CdS and HgS samples respectively.
Temperature and Time Requirements for Controlling Bed Bugs (Cimex lectularius) under Commercial Heat Treatment Conditions
Authors: Kells Stephen A. , Goblirsch Michael J.
Published: August 2011

Developing effective alternative approaches for disinfesting bed bugs from residential spaces requires a balance between obtaining complete insect mortality, while minimizing costs and energy consumption. One method of disinfestation is the application of lethal high temperatures directly to rooms and contents within a structure (termed whole-room heat treatments). However, temperature and time parameters for efficacy in whole-room heat treatments are unknown given the slower rate of temperature increase and the probable variability of end-point temperatures within a treated room. The objective of these experiments was to explore requirements to produce maximum mortality from heat exposure using conditions that are more characteristic of whole-room heat treatments. Bed bugs were exposed in an acute lethal temperature (LTemp) trial, or time trials at sub-acute lethal temperatures (LTime). The lethal temperature (LTemp99) for adults was 48.3 °C, while LTemp99 for eggs was 54.8 °C. Adult bed bugs exposed to 45 °C had a LTime99 of 94.8 min, while eggs survived 7 h at 45 °C and only 71.5 min at 48 °C. We discuss differences in exposure methodologies, potential reasons why bed bugs can withstand higher temperatures and future directions for research.
Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin
Authors: Wilson Lee D. , Mohamed Mohamed H. , Berhaut Christopher L.
Published: August 2011

Urethane copolymer sorbent materials that incorporate β-cyclodextrin (CD) have been prepared and their sorption properties with chlorinated aromatic compounds (i.e., pentachlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid) have been evaluated. The sorption properties of granular activated carbon (GAC) were similarly compared in aqueous solution at variable pH conditions. The sorbents displayed variable BET surface areas as follows: MDI-X copolymers (< 101 m2/g), CDI-X copolymers (< 101 m2/g), and granular activated carbon (GAC ~103 m2/g). The sorption capacities for the copolymers sorbents are listed in descending order, as follows: GAC > CDI-3 copolymer ≈ MDI-3 copolymer. The sorption capacity for the aromatic adsorbates with each sorbent are listed in descending order, as follows: 2,4-dichlorophenol > 2,4-dichlorophenoxy acetic acid > pentachlorophenol. In general, the differences in the sorption properties of the copolymer sorbents with the chlorinated organics were related to the following factors: (i) surface area of the sorbent; (ii) CD content and accessibility; and (iii) and the chemical nature of the sorbent material.
Production of Bioactive Secondary Metabolites by Marine Vibrionaceae
Authors: Mansson Maria , Gram Lone , Larsen Thomas O.
Published: August 2011

Bacteria belonging to the Vibrionaceae family are widespread in the marine environment. Today, 128 species of vibrios are known. Several of them are infamous for their pathogenicity or symbiotic relationships. Despite their ability to interact with eukaryotes, the vibrios are greatly underexplored for their ability to produce bioactive secondary metabolites and studies have been limited to only a few species. Most of the compounds isolated from vibrios so far are non-ribosomal peptides or hybrids thereof, with examples of N-containing compounds produced independent of nonribosomal peptide synthetases (NRPS). Though covering a limited chemical space, vibrios produce compounds with attractive biological activities, including antibacterial, anticancer, and antivirulence activities. This review highlights some of the most interesting structures from this group of bacteria. Many compounds found in vibrios have also been isolated from other distantly related bacteria. This cosmopolitan occurrence of metabolites indicates a high incidence of horizontal gene transfer, which raises interesting questions concerning the ecological function of some of these molecules. This account underlines the pending potential for exploring new bacterial sources of bioactive compounds and the challenges related to their investigation.
Flow Injection Spectrophotometric Determination of N-Acetyl-L-cysteine as a Complex with Palladium(II)
Authors: Giljanović Josipa , Brkljača Mia , Prkić Ante
Published: August 2011

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd2+ ions in the concentration range from 1.0 × 10−5 mol L−1 to 6.0 × 10−5 mol L−1. The detection limit NAC was 5.84 × 10−6 mol L−1 and the recorded relative standard deviation of the method is in the range from 1.67 to 4.11%. NAC and Pd2+ form complexes of Pd2+:NAC molar ratios of 1:1 and 1:2, depending on the ratio of their analytical concentrations. The cumulative conditional stability constant for the Pd(NAC)22+ complex is β12' = 2.69 × 109 L2 mol−2. The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl2, and had shown certain advantages: a) shorter analysis time; b) the use of smaller volumes of sample and reagents, which make the proposed method cheaper and faster for NAC determination in real samples without sample pretreatment.
Synthesis of Silver Nanoparticles in Chitosan, Gelatin and Chitosan/Gelatin Bionanocomposites by a Chemical Reducing Agent and Their Characterization
Authors: Bin Ahmad Mansor , Lim Jenn Jye , Shameli Kamyar , Ibrahim Nor Azowa , Tay Mei Yen
Published: August 2011

In this research, silver nanoparticles (AgNPs) were synthesized in chitosan (Cts), Cts/gelatin and gelatin suspensions using a chemical reducing agent. Cts and gelatin were used as natural stabilizers and solid support, whereas AgNO3 was used as the silver precursor. Sodium borohydride (NaBH4) was used as the reducing agent. The properties of AgNPs in Cts, Cts/gelatin and gelatin bionanocomposites (BNCs) were studied in terms of their surface plasmon resonance, crystalline structure, average diameter size, particle distributions, surface topography and functional groups. All the samples were characterized by UV-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy.
A Novel Cyclodione Coumarin from the Stem Bark of Mesua beccariana
Authors: Ee Gwendoline Cheng Lian , Teh Soek Sin , Mah Siau Hui , Rahmani Mawardi , Taufiq-Yap Yun Hin , Awang Khalijah
Published: August 2011

Our ongoing investigations on the stem bark of Mesua beccariana afforded a novel cyclodione coumarin, beccamarin, together with two known xanthones, mesuarianone, mesuasinone, two anthraquinones, 4-methoxy-1,3,5-trihydroxy-anthraquinone and 2,5-dihydroxy-1,3,4-trimethoxyanthraquinone and one coumarin, mammea A/AB. The structures were elucidated by 1D and 2D NMR and MS techniques.
Cyclization vs. Cyclization/Dimerization in o-Amidostilbene Radical Cation Cascade Reactions: The Amide Question
Authors: Kee Chin Hui , Ariffin Azhar , Awang Khalijah , Noorbatcha Ibrahim , Takeya Koichi , Morita Hiroshi , Lim Chuan Gee , Thomas Noel Francis
Published: August 2011

The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl3 promoted cyclization to produce only indoline, while n-butyramidostilbene, under the same conditions, produces both indoline and bisindoline.
Antioxidant Capacity of Ocimum basilicum L. and Origanum vulgare L. Extracts
Authors: Kaurinovic Biljana , Popovic Mira , Vlaisavljevic Sanja , Trivic Svetlana
Published: August 2011

The antioxidant properties of five different extracts (Et2O, CHCl3, EtOAc, n-BuOH, and H2O) of Ocimum basilicum L. and Origanum vulgare L. were studied. Antioxidant activity was assessed in six different model systems. Free radical scavenging capacity (RSC) was evaluated by measuring the scavenging capacity of extracts on DPPH, NO, O2·- and OH radical, as well as on hydrogen peroxide (H2O2). In addition, the protective effects on lipid peroxidation in liposomes (LPx) were evaluated by TBA-assay using the Fe2+/ascorbate induction system. The amount of total phenolic compounds and content of total flavonoids was also determined. EtOAc, n-BuOH and H2O extracts of O. basilicum and O. vulgare expressed very strong scavenger activity. Furthermore, the mentioned extracts showed notable inhibition of LPx. On the other hand, Et2O and CHCl3 extracts showed much weaker effect in the neutralization of DPPH, NO and O2·- radicals and the neutralization of H2O2. When examining the production of OH radicals and inhibition of LPx, the Et2O and CHCl3 extracts showed weak prooxidative properties. The observed differences in antioxidant activity could be partially explained by the levels of phenolics and flavonoids in the investigated O. basilicum and O. vulgare extracts.
Investigation of the Atypical Glass Transition and Recrystallization Behavior of Amorphous Prazosin Salts
Authors: Kumar Lokesh , Popat Dharmesh , Bansal Arvind K.
Published: August 2011

This manuscript studied the effect of counterion on the glass transition and recrystallization behavior of amorphous salts of prazosin. Three amorphous salts of prazosin, namely, prazosin hydrochloride, prazosin mesylate and prazosin tosylate were prepared by spray drying, and characterized by optical-polarized microscopy, differential scanning calorimetry and powder X-ray diffraction. Modulated differential scanning calorimetry was used to determine the glass transition and recrystallization temperature of amorphous salts. Glass transition of amorphous salts followed the order: prazosin mesylate > prazosin tosylate ~ prazosin hydrochloride. Amorphous prazosin mesylate and prazosin tosylate showed glass transition, followed by recrystallization. In contrast, amorphous prazosin hydrochloride showed glass transition and recrystallization simultaneously. Density Functional Theory, however, suggested the expected order of glass transition as prazosin hydrochloride > prazosin mesylate > prazosin tosylate. The counterintuitive observation of amorphous prazosin hydrochloride having lower glass transition was explained in terms of its lower activation energy (206.1 kJ/mol) for molecular mobility at Tg, compared to that for amorphous prazosin mesylate (448.5 kJ/mol) and prazosin tosylate (490.7 kJ/mol), and was further correlated to a difference in hydrogen bonding strength of the amorphous and the corresponding recrystallized salts. This study has implications in selection of an optimal amorphous salt form for pharmaceutical development.
Poly Lactic-co-Glycolic Acid (PLGA) as Biodegradable Controlled Drug Delivery Carrier
Authors: Makadia Hirenkumar K. , Siegel Steven J.
Published: August 2011

In past two decades poly lactic-co-glycolic acid (PLGA) has been among the most attractive polymeric candidates used to fabricate devices for drug delivery and tissue engineering applications. PLGA is biocompatible and biodegradable, exhibits a wide range of erosion times, has tunable mechanical properties and most importantly, is a FDA approved polymer. In particular, PLGA has been extensively studied for the development of devices for controlled delivery of small molecule drugs, proteins and other macromolecules in commercial use and in research. This manuscript describes the various fabrication techniques for these devices and the factors affecting their degradation and drug release.
Consolidation of Inorganic Precipitated Silica Gel
Authors: Sahabi Hussein , Kind Matthias
Published: August 2011

Colloidal gels are possible intermediates in the generation of highly porous particle systems. In the production process the gels are fragmented after their formation. These gel fragments compact to particles whose application-technological properties are determined by their size and porosity. In the case of precipitated silica gels, this consolidation process depends on temperature and pH, among other parameters. It is shown that these dependencies can be characterized by oedometer measurements. Originally, the oedometer test (one-dimensional compression test) stemmed from soil mechanics. It has proven to be an interesting novel examination method for gels. Quantitative data of the time-dependent shrinkage of gel samples can be obtained. The consolidation of the gels shows a characteristic dependence on the above parameters.
Prophesying Women and Ruling Men: Women’s Religious Authority in North American Pentecostalism
Authors: Stephenson Lisa P.
Published: August 2011

The issue of religious authority is one of the main reasons why women have been allowed to participate in Pentecostal churches, and why they have been limited. Women are granted access to ministering authority, but not governing authority. Charles Barfoot and Gerald Sheppard have noted the presence of these two types of authority to be operative within Pentecostalism and have associated them with Max Weber’s typology of prophet and priest. However, in their attempt to describe the history of Pentecostal women in ministry with these categories, Barfoot and Sheppard present the paradigm as one of displacement rather than coexistence. The result is a problematic and misleading account of Pentecostal women in ministry. However, the issue is not Weber’s categories, but how they employ them. The purpose of this article is to utilize the distinction between prophet and priest to differentiate between two types of ecclesial functions and their concomitant religious authority, rather than to differentiate between two periods of Pentecostalism. A brief history of Pentecostal women in ministry is presented, wherein examples are offered of how women in the Church of God, the Church of God in Christ, the Assemblies of God, and the International Church of the Foursquare Gospel operated in the prophetic realms with a ministering authority, but were largely prohibited from the priestly realms and its ruling authority. As these examples demonstrate, the history of Pentecostal women in ministry is told best when the simultaneous existence of the prophetic and priestly functions are recognized, and ministering authority and ruling authority are connected to these two functions.
Downscaling Pesticide Use Data to the Crop Field Level in California Using Landsat Satellite Imagery: Paraquat Case Study
Authors: Maxwell Susan K.
Published: August 2011

Exposure to pesticides has been associated with increased risk of many adverse health effects. To understand the relationships between pesticide exposure and health outcomes, epidemiologists need information on where pesticides are applied in the environment. California maintains one of the most comprehensive pesticide use reporting systems in the world, yet the data are only recorded at a coarse geographic scale of approximately 2.6 km2 area. A method is presented that uses Landsat image time series to downscale California pesticide use data to the crop field-level. The approach is demonstrated using paraquat applied to vineyard and cotton fields.
Micro-Raman Spectroscopy and Univariate Analysis for Monitoring Disease Follow-Up
Authors: Camerlingo Carlo , Delfino Ines , Perna Giuseppe , Capozzi Vito , Lepore Maria
Published: August 2011

Micro-Raman spectroscopy is a very promising tool for medical applications, thanks to its sensitivity to subtle changes in the chemical and structural characteristics of biological specimens. To fully exploit these promises, building a method of data analysis properly suited for the case under study is crucial. Here, a linear or univariate approach using a R2 determination coefficient is proposed for discriminating Raman spectra even with small differences. The validity of the proposed approach has been tested using Raman spectra of high purity glucose solutions collected in the 600 to 1,600 cm−1 region and also from solutions with two known solutes at different concentrations. After this validation step, the proposed analysis has been applied to Raman spectra from oral human tissues affected by Pemphigus Vulgaris (PV), a rare life-threatening autoimmune disease, for monitoring disease follow-up. Raman spectra have been obtained in the wavenumber regions from 1,050 to 1,700 cm−1 and 2,700 to 3,200 cm−1 from tissues of patients at different stages of pathology (active PV, under therapy and PV in remission stage) as confirmed by histopathological and immunofluorescence analysis. Differences in the spectra depending on tissue illness stage have been detected at 1,150–1,250 cm−1 (amide III) and 1,420–1,450 cm−1 (CH3 deformation) regions and around 1,650 cm−1 (amide I) and 2,930 cm−1 (CH3 symmetric stretch). The analysis of tissue Raman spectra by the proposed univariate method has allowed us to effectively differentiate tissues at different stages of pathology.
Development of an Integrated Microfluidic Perfusion Cell Culture System for Real-Time Microscopic Observation of Biological Cells
Authors: Lin Jr-Lung , Wang Shih-Siou , Wu Min-Hsien , Oh-Yang Chih-Chin
Published: August 2011

This study reports an integrated microfluidic perfusion cell culture system consisting of a microfluidic cell culture chip, and an indium tin oxide (ITO) glass-based microheater chip for micro-scale perfusion cell culture, and its real-time microscopic observation. The system features in maintaining both uniform, and stable chemical or thermal environments, and providing a backflow-free medium pumping, and a precise thermal control functions. In this work, the performance of the medium pumping scheme, and the ITO glass microheater were experimentally evaluated. Results show that the medium delivery mechanism was able to provide pumping rates ranging from 15.4 to 120.0 μL·min−1. In addition, numerical simulation and experimental evaluation were conducted to verify that the ITO glass microheater was capable of providing a spatially uniform thermal environment, and precise temperature control with a mild variation of ±0.3 °C. Furthermore, a perfusion cell culture was successfully demonstrated, showing the cultured cells were kept at high cell viability of 95 ± 2%. In the process, the cultured chondrocytes can be clearly visualized microscopically. As a whole, the proposed cell culture system has paved an alternative route to carry out real-time microscopic observation of biological cells in a simple, user-friendly, and low cost manner.
Novel Wireless Sensor System for Monitoring Oxygen, Temperature and Respiration Rate of Horticultural Crops Post Harvest
Authors: Løkke Mette Marie , Seefeldt Helene Fast , Edwards Gareth , Green Ole
Published: August 2011

In order to design optimal packages, it is of pivotal importance to determine the rate at which harvested fresh fruits and vegetables consume oxygen. The respiration rate of oxygen (RRO2) is determined by measuring the consumed oxygen per hour per kg plant material, and the rate is highly influenced by temperature and gas composition. Traditionally, RRO2 has been determined at discrete time intervals. In this study, wireless sensor networks (WSNs) were used to determine RRO2 continuously in plant material (fresh cut broccoli florets) at 5 °C, 10 °C and 20 °C and at modified gas compositions (decreasing oxygen and increasing carbon dioxide levels). Furthermore, the WSN enabled concomitant determination of oxygen and temperature in the very close vicinity of the plant material. This information proved a very close relationship between changes in temperature and respiration rate. The applied WSNs were unable to determine oxygen levels lower than 5% and carbon dioxide was not determined. Despite these drawbacks in relation to respiration analysis, the WSNs offer a new possibility to do continuous measurement of RRO2 in post harvest research, thereby investigating the close relation between temperature and RRO2. The conclusions are that WSNs have the potential to be used as a monitor of RRO2 of plant material after harvest, during storage and packaging, thereby leading to optimized consumer products.
High-Dimensional Random Matrices from the Classical Matrix Groups, and Generalized Hypergeometric Functions of Matrix Argument
Authors: Richards Donald St. P.
Published: August 2011

Results from the theory of the generalized hypergeometric functions of matrix argument, and the related zonal polynomials, are used to develop a new approach to study the asymptotic distributions of linear functions of uniformly distributed random matrices from the classical compact matrix groups. In particular, we provide a new approach for proving the following result of D’Aristotile, Diaconis, and Newman: Let the random matrix Hn be uniformly distributed according to Haar measure on the group of n × n orthogonal matrices, and let An be a non-random n × n real matrix such that tr (A'nAn) = 1. Then, as n→∞, √n tr AnHn converges in distribution to the standard normal distribution.
Impact of the Nature and Size of the Polymeric Backbone on the Ability of Heterobifunctional Ligands to Mediate Shiga Toxin and Serum Amyloid P Component Ternary Complex Formation
Authors: Kitov Pavel I. , Paszkiewicz Eugenia , Sadowska Joanna M. , Deng Zhicheng , Ahmed Marya , Narain Ravin , Griener Thomas P. , Mulvey George L. , Armstrong Glen D. , Bundle David R.
Published: August 2011

Inhibition of AB5-type bacterial toxins can be achieved by heterobifunctional ligands (BAITs) that mediate assembly of supramolecular complexes involving the toxin’s pentameric cell membrane-binding subunit and an endogenous protein, serum amyloid P component, of the innate immune system. Effective in vivo protection from Shiga toxin Type 1 (Stx1) is achieved by polymer-bound, heterobifunctional inhibitors-adaptors (PolyBAITs), which exhibit prolonged half-life in circulation and by mediating formation of face-to-face SAP-AB5 complexes, block receptor recognition sites and redirect toxins to the spleen and liver for degradation. Direct correlation between solid-phase activity and protective dose of PolyBAITs both in the cytotoxicity assay and in vivo indicate that the mechanism of protection from intoxication is inhibition of toxin binding to the host cell membrane. The polymeric scaffold influences the activity not only by clustering active binding fragments but also by sterically interfering with the supramolecular complex assembly. Thus, inhibitors based on N-(2-hydroxypropyl) methacrylamide (HPMA) show significantly lower activity than polyacrylamide-based analogs. The detrimental steric effect can partially be alleviated by extending the length of the spacer, which separates pendant ligand from the backbone, as well as extending the spacer, which spans the distance between binding moieties within each heterobifunctional ligand. Herein we report that polymer size and payload of the active ligand had moderate effects on the inhibitor’s activity.
Hydrologic Response Unit Routing in SWAT to Simulate Effects of Vegetated Filter Strip for South-Korean Conditions Based on VFSMOD
Authors: Park Youn Shik , Park Jeong Hee , Jang Won Seok , Ryu Ji Chul , Kang Hyunwoo , Choi Joongdae , Lim Kyoung Jae
Published: August 2011

The Soil and Water Assessment Tool (SWAT) model has been used worldwide for many hydrologic and Non-Point Source (NPS) Pollution analyses on a watershed scale. However, it has many limitations in simulating the Vegetative Filter Strip (VFS) because it considers only ‘filter strip width’ when the model estimates sediment trapping efficiency and does not consider the routing of sediment with overland flow which is expected to maximize the sediment trapping efficiency from upper agricultural subwatersheds to lower spatially-explicit filter strips. Therefore, the SWAT overland flow option between landuse-subwatersheds with sediment routing capability was enhanced by modifying the SWAT watershed configuration and SWAT engine based on the numerical model VFSMOD applied to South-Korean conditions. The enhanced SWAT can simulate the VFS sediment trapping efficiency for South-Korean conditions in a manner similar to the desktop VFSMOD-w system. Due to this enhancement, SWAT is applicable to simulate the effects of overland flow from upper subwatersheds to reflect increased runoff volume at the lower subwatershed, which occurs in the field if no diversion channel is installed. In this study, the enhanced SWAT model was applied to small watersheds located at Jaun-ri in South-Korea to simulate a diversion channel and spatially-explicit VFS. Sediment can be reduced by 31%, 65%, and 68%, with a diversion channel, the VFS, and the VFS with diversion channel, respectively. The enhanced SWAT should be used in estimating site-specific effects on sediment reduction with diversion channels and VFS, instead of the currently available SWAT, which does not simulate sediment routing in overland flow and does not consider other sensitive factors affecting sediment reduction with VFS.
Prévision du taux de change dollar canadien contre dollar américain : une approche en termes de "fondamentaux"
Authors: Taylor Mark P.
Published: August 2011

Forecasting the Canadian-US Dollar Exchange Rate: An Approach in Terms of "Fundamentals"

by Mark P. Taylor

We develop and estimate a forecasting equation for the Canadian-US dollar exchange rate by conditioning on short-run and determinants of the exchange rate. The equation performs well compared with an equation developed by the Bank of is statistically well-determined. The model does, however, have certain Keynesian features which, at the long-run intriguing.
Crédibilité et fondamentaux macro-économiques au sein du SME : un examen empirique
Authors: Cœuré Benoît , Magnier Antoine
Published: August 2011

Crédibilité et fondamentaux macro-économiques au sein du SME : un examen empirique

par Benoît Cœuré et Antoine Magnier

Le lien entre la crédibilité des parités au sein du SME et l'évolution des fondamentaux macro-économiques est au centre du débat économique né au lendemain des crises de change de 1992 et 1993. Cette étude propose une évaluation empirique de ce lien durant la période 1983-1 993 . Dans un premier temps, nous construisons une mesure des anticipations de dévaluation des parités franc/mark et lire/mark à partir de la méthode dite de "correction de la dérive" du taux de change dans un régime de zone-cible. Dans un second temps, à partir d'une modélisation War non-stationnaire, des tests de causalité au sens de Granger et le calcul de fonctions de réponse à des chocs macro-économiques permettent d'évaluer le rôle des fondamentaux dans la formation des anticipations de dévaluation. Certaines variables macro-économiques semblent bien affecter la crédibilité des parités considérées sur la période 1983-1993 mais ces liens apparaissent généralement peu intuitifs et peu significatifs d'un point de vue économique. On constate toutefois que l'effet de chocs exogènes sur la crédibilité de la parité franc/mark tend à s'estomper assez rapidement tandis que cet effet semble très persistant dans le cas de la parité lire/mark. Les résultats ne permettent pas de conclure véritablement quant à la nature des crises de change de 1992 et 1993 mais suggèrent que l'explication théorique des crises en terme d'équilibres multiples puisse être en partie justifiée. Ils soulignent surtout la nécessité d'une approche économétrique plus structurelle.
Les modèles de crise de change : un essai de synthèse en relation avec la crise du franc de 1992-1993
Authors: Jeanne Olivier
Published: August 2011

Les modèles de crise de change : un essai de synthèse en relation avec la crise du franc de 1992-1993

par Olivier Jeanne

Cet article tente de présenter et comparer dans un cadre synthétique les mécanismes de crise de change proposés par la théorie économique; dégager les hypothèses qu'ils suggèrent sur l'origine de la crise du franc de 1992-1993, avant de les confronter aux "faits stylisés". On distingue deux approches théoriques, celle des modèles d'attaque spéculative et l'approche avec "clause de sortie". Les modèles d'attaque spéculative concentrent l'analyse sur le phénomène de fuite des réserves de change qui se produit au moment de la crise. Dans l'approche avec clause de sortie, on s'interroge plutôt sur les raisons pour lesquelles les autorités monétaires choisissent de défendre ou non la monnaie quand elle est attaquée. L'approche avec clause de sortie permet de faire le lien entre la crise du franc et certains fondamentaux comme le chômage français ou la politique monétaire allemande. Par ailleurs, les deux approches sont compatibles avec l'hypothèse selon laquelle la crise du franc n'était pas causée par les fondamentaux, mais autoréalisatrice.
Incertitude, arbitrage et taux de change
Authors: Viviani Jean-Laurent
Published: August 2011

Incertitude, arbitrage et taux de change par Jean-Laurent Viviani

Sans nier la pertinence des explications proposées de l'existence de fourchettes de prix sur les marchés financiers, nous montrons qu'elles pourraient également être la conséquence du comportement rationnel des agents dans un environnement non probabilisable. Dans ce cadre, l'aversion des agents à l'incertitude est à l'origine d'un écart entre le prix offert et demandé qui est compatible avec l'absence d'opportunités d'arbitrage.
Structure de coût généralisée et horaire optimal
Authors: Contensou François , Vranceanu Radu
Published: August 2011

General Cost Structure and Optimal Working Hours François Contensou and Radu Vranceanu

This study endeavours to show the role that indirect labour costs can play in explaining the working week formed spontaneously in a decentralised economy. The first part of the paper considers production to be predetermined by a market outlet constraint. The model is then generalised by considering the activity level of firms to be endogenous. The analysis reveals the systematic formation of a working hours conflict and shows the determining factors behind this conflict. It is also possible to use this framework to represent the effects of legal reductions in working hours, advocated as a tool for curbing unemployment. The findings here are inconclusive. The study specifies the conditions needed for these government-imposed working- week reductions to really encourage firms to hire more employees.
Incidences du mode de prélèvement des cotisations sociales
Authors: Van Haeperen Béatrice
Published: August 2011

Incidences du mode de prélèvement des cotisations sociales. Un modèle d'équilibre général

avec revenu minimum

Béatrice Van Haeperen

La hausse des cotisations de sécurité sociale observée dans les années quatre-vingts et rendue nécessaire pour assurer la couverture d'un chômage croissant a pu constituer un frein à l'embauche. Dans un modèle d'équilibre général avec revenu réel minimum et cotisations sociales prélevées sur les salaires, sur le profit ou sur la valeur ajoutée, nous articulons la relation entre revenu minimum, assiette de prélèvement des cotisations sociales, salaire minimum et emploi et montrons que dissocier les prélèvements de cotisations sociales des salaires permettrait d'atteindre un niveau d'emploi plus élevé sans baisse du revenu disponible des travailleurs. Le passage d'un prélèvement sur les salaires à un prélèvement sur les profits ou sur la valeur ajoutée pourrait être utilisé comme instrument de résorption du chômage. Dans chaque cas, nous examinons l'impact sur le déficit budgétaire.
Vers une modélisation macro-économique rationnelle ?
Authors: Malgrange Pierre
Published: August 2011

Towards Rational Macroeconomic Modeling? Pierre Malgrange

The purpose of this paper is to explain and evaluate the strengths and weaknesses of the quarterly PLM model of the French economy, which is based on a pattern of intertemporal optimisation and rational expectations. We first of all present a very simple specification, which is similar to the canonical model of optimal growth and integrates government spending. This structure is then enhanced step by step, first by the opening up of the economy and the factoring in of nominal wage rigidity. Then we introduce monopolistic competition and lastly various viscosities resulting in the persistence of a certain number of mechanisms. Characterisation is attained by making a "responses to impetus" analysis, i.e. by calculating the multipliers associated with the two generic supply and demand shocks.
Fiscalité, charges sociales, qualifications et emploi
Authors: Laffargue Jean-Pierre
Published: August 2011

Fiscalité, charges sociales, qualifications et emploi. Étude à l'aide du modèle d'équilibre général calculable

de l'économie française : "Julien"

Jean-Pierre Laffargue

De 1960 à nos jours le taux de chômage a augmenté tendanciellement beaucoup plus pour les travailleurs non qualifiés que pour les qualifiés. Nous pouvons donc penser qu'une politique de lutte contre le chômage doit d'abord concerner le premier type d'emplois. Cet article analyse les effets économiques, en particulier ceux sur l'emploi, de réductions des cotisations sociales sur les différentes qualifications, ainsi que des autres impôts. Pour cela nous utilisons une maquette de l'économie française, "Julien", qui adopte un cadre de concurrence monopolistique, a un caractère dynamique, attribue aux agents des comportements d'optimisation intertemporelle avec anticipations rationnelles et inclut une modélisation fine du marché du travail.
Hétérogénéité des prévisionnistes : une exploration des anticipations sur le marché des changes
Authors: MacDonald Ronald , Marsh Ian W.
Published: August 2011

Forecaster Heterogeneity: An Investigation of the Expectations of Foreign Exchange Forecasters

Ronald MacDonald and Ian W. Marsh

Adatabase of individual forecasters' exchange rate predictions is analysed. We demonstrate that only a small subgroup of forecasters can be described as rational, that some forecasters are significantly more accurate than others, and that this heterogeneity of expectations is positively related to trading volume in the futures market.
Les erreurs de prévision de change ont-elles des caractéristiques hétérogènes ?
Authors: Benassy-Quéré Agnès , Raymond Hélène
Published: August 2011

Exchange Rate Forecasting Errors Using Survey Data: Are the Characteristics Homogenous or Heterogeneous?

Agnès Bénassy-Quéré and Hélène Raymond

Surveys of expectations provide valuable information on speculative exchange rate behaviour. We analyse the properties of forecasting errors for three exchange rates against the dollar (deutschemark, yen and pound sterling) and one exchange rate against the deutschemark (French franc). We use a set of descriptive statistics and econometric tests to identify the main characteristics of the forecasting errors and detect any differences across the forecasting ranges, the currencies and the periods. Three partially intersecting surveys (Economist, Consensus Forecasts and Banque Nationale de Paris) are used to check the universality of the results obtained and to envisage a fourth source of heterogeneity: disparities in the forecasting methods used by the different participants. We conclude that the characteristics of forecasting errors are more heterogeneous in terms of currencies and periods than in terms of forecasting ranges and surveys.
Progrès technique et croissance de la productivité : estimations sur un panel incomplet de firmes ayant des qualités de production différentes
Authors: Dionne Georges , Gagné Robert
Published: August 2011

Measuring Technical Change and Productivity Growth with Varying Output Qualities

and Incomplete Panel Data par Georges Dionne and Robert Gagné

This paper presents a method for estimating technical change using incomplete panel data. In addition, we show how estimates of cost elasticities with respect to output qualities can be used to evaluate productivity growth adjusted for quality changes. In order to control for the incomplete nature of the sample used, specific dummy variables for entry in and exit from the sample are introduced into the cost function. The proposed methodology is applied to an unbalanced sample of trucking firms from Quebec. Results show that without correction for sample entry or exit, the estimated rate of technical change between 1987 and 1988 is -29,7%. When entry in or exit from the sample is taken into account, the estimated rate is -4,2%. Also, during the same period, the observed TFP growth rate is 63.4%. After adjustment for quality changes, this rate falls to -4,6%.
Le ralentissement de la productivité des entreprises d'électricité au Texas : le rôle des marges, des rendements d'échelle et du progrès technique
Authors: Kumbhakar Subal C.
Published: August 2011

Le ralentissement de la productivité des entreprises d'électricité au Texas :

le rôle des marges, des rendements d'échelle et du progrès technique

par Subal C. Kumbhakar

Cet article présente un modèle de maximisation du profit de la firme permettant de mesurer la croissance de la productivité totale des facteurs (PTF) et de la décomposer en trois éléments reliés au progrès technique, aux rendements d'échelle et à l'existence de marges sur les coûts. Le progrès technique est ensuite décomposé en un progrès technique pur, un progrès technique non neutre et un progrès technique augmentant l'échelle de production. Nous examinons le rôle de ces facteurs dans l'explication de la croissance de la PTF d'entreprises de production d'électricité dans l'État du Texas. Une caractéristique intéressante de cette étude réside dans l'utilisation de données de panel relatives à des entreprises d'électricité de l'État du Texas, observées entre 1966 et 1985, période qui inclut la période de réglementation des tarifs par les autorités publiques. L'utilisation de données de panel permet de modéliser le comportement de fixation des marges dans le temps sans avoir besoin d'imposer des contraintes a priori sur ces évolutions. Ces données permettent également de prendre en compte l'hétérogénéité des structures de coût des entreprises. Les résultats des estimations montrent que les marges et la croissance de la PTF ont sensiblement baissé durant la période de réglementation. Malgré cela, sur l'ensemble de la période étudiée, les comportements de fixation des marges par les entreprises ont largement contribué aux hausses de productivité observées.
La productivité de la recherche et développement des entreprises industrielles aux États-Unis et en France
Authors: Mairesse Jacques , Hall Bronwyn H.
Published: August 2011

La productivité de la recherche et développement des entreprises industrielles aux États-Unis et en France

par Jacques Mairesse et Bronwyn H. Hall

II s'agit d'une étude comparée du degré de contribution de la R&D à la productivité au niveau de l'entreprise en ce qui concerne les sociétés manufacturières en France et aux États-Unis. L'étude utilise deux grands panels d'environ mille entreprises manufacturières auxquelles correspond plus de la moitié des dépenses R&D dans l'un et l'autre pays ; elle est centrée sur l'estimation et l'interprétation de la relation existant entre la croissance de la production et la croissance des investissements R&D en cas de simultanéité et d'hétérogénéité des entreprises. Nous utilisons les méthodes MGG pour contrôler l'une et l' autre sources de distorsion de l'estimation et nous constatons que : fait prédominant la contribution de la R&D à la croissance de la productivité des ventes semble être allé diminuant au cours des années quatre-vingts ; le rôle du biais de simultanéité est plus marqué aux État-Unis qu'en France, ce qui correspond peut-être à l'importance plus grande des contraintes de liquidités qui pèsent sur les investissements aux États-Unis.
Estimation des élasticités de court et de long termes de la demande d'électricité sur données de panel à partir d'estimateurs à rétrécisseur
Authors: Li Hongyi , Maddala G.S. , Trost Robert P.
Published: August 2011

Estimation des élasticités de court et de long termes de la demande d'électricité sur données de panel à partir d'estimateurs à rétrécisseurs

par Hongyi Li, G.S. Maddala et Robert P. Trost

On peut distinguer trois approches dans l'analyse des données de panel. L'estimation séparée des paramètres sur chaque série individuelle,1 l'estimation sur données empilées, avec ou sans effets spécifiques, et l'estimation sur données empilées en admettant un certain degré d'hétérogénéité, comme dans le modèle à coefficients aléatoires. Dans ce dernier cas, c'est la moyenne des coefficients des' séries individuelles qui nous intéresse. Cet article présente dans un cadre unifié,' les estimateurs relevant de cette troisième catégorie» en recourant à la fois à l'approche classique, à l'approche bayésienne empirique et à l'approche bayésienne classique. Ces méthodes sont illustrées par l'estimation d'élasticités de la demande d'électricité et de gaz naturel des ménages, aux États-Unis.
Tests de causalité sur données de panel : une application à l'étude de la causalité entre l'investissement et la croissance
Authors: Weinhold Diana
Published: August 2011

Causaliy Testing in Panel Data with an Application to the Question of Investment and Growth

by Diana Weinhold

This paper develops an approach for panel causality analysis which allows for flexibility in the causal relationship from unity to unity, allowing estimation of distribution of causality in a possibly heterogeneous panel. Two possible estimation techniques for "mixed fixed and random" coefficients model are explored. These methods both allow the coefficients of an orthogonalized causal variable to vary randomly while avoiding many of the problems associated with random coefficients and dynamics in panels. Using simulations to develop a method for interpreting the estimated distributions, it is then possible to predict the probabilities of causality associated with the panel.

This approach is then applied to the question of causality between investment and growth in a panel of countries. The paper find that there is great instability and feedback among countries in this relationship. Therefore, it is clear that the restricting assumptions of traditional pooling models can be inappropriate, especially in simple models. Because the analysis signals this problem, the paper's results further underline the need for the interpretive flexibility that this proposed causality test imparts.
Utilisation jointe de données de panel et d'informations agrégées dans l'estimation d'un modèle Probit
Authors: Laisney François , Lechner Michael
Published: August 2011

Combining Panel Data and Macro Information for the Estimation of a Panel Probit Model

by François Laisney and Michael Lechner

When studying particular subgroups of a population the econometrician typically has few observations, and should draw upon any additional relevant information. We illustrate, for the estimation of a labour-market participation model for lone mothers, the relative benefits derived from using the panel structure of the data in a GMM framework and from including macro information in the form of extra moments.
L'Organisation commune de marché dans l'Union européenne : impact de la taille du contingent tarifaire appliqué aux bananes dollar et non traditionnelles ACP
Authors: Guyomard Hervé , Herrard Nadine , Laroche Catherine , Le Mouël Chantal
Published: August 2011

L'Organisation commune de marché de la banane dans l'Union européenne : impact de la taille du contingent

tarifaire appliqué aux bananes dollar et non traditionnelles ACP par Hervé Guyomard, Nadine Herrard, Catherine Laroche et Chantai Le Mouël

Le 1er Juillet 1993, l'Union européenne (UE) a finalement instauré un marché commun de la banane. L'Organisation commune de marché (OCM) mise en place remplace un ensemble de politiques nationales complexes et hétérogènes, incompatibles avec le Marché Unique. La nouvelle réglementation repose essentiellement sur i) la fixation d'un contingent tarifaire dans l'UE pour les bananes d'Amérique latine et non traditionnelles ACP (Afrique, Caraïbes et Pacifique), et ii) le concept de partenariat entre le commerce de bananes communautaires et traditionnelles ACP d'une part, et le commerce de bananes d'Amérique latine d'autre part. L'objet de cet article est double. Il s'agit en premier lieu de proposer un cadre simplifié d'analyse du fonctionnement du marché mondial de la banane en régime d'OCM dans l'UE. Il s'agit en second lieu d'analyser la sensibilité des équilibres de marché à la taille du contingent tarifaire imposé par l'UE aux bananes d'Amérique latine et non traditionnelles ACP sur la base de simulations réalisées à l'aide d'un modèle d'équilibre partiel du marché mondial de la banane.