bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Electrochemistry of Tetraphenyl Porphyrin Iron(III) Within Immobilized Droplets Supported on Platinum Electrodes
Authors: Munoz Rodrigo A. A. , Banks Craig E. , Davies Trevor J. , Angnes Lucio , Compton Richard G. 
Published: February 2006

AbstractFor the first time, the voltammetry of an ensemble of immobilized benzonitrile microdroplets containing 5,10,15,20‐tetraphenyl‐21H,23H‐porphine iron (III) chloride, TPPFeCl immobilized at platinum electrodes immersed in various aqueous electrolytes has been explored. The reduction of TPPFeCl was observed with the voltammetric response seen to be highly dependent on the nature of ions in the surrounding aqueous phase. Unlike voltammetry in purely homogeneous solution the nature of the aqueous electrolyte can influence the voltammetry in the droplet phase. The electrochemical reduction of TPPFeCl contained within tetrabutylammonium chloride (TBACl) supported benzonitrile (PhCN) microdroplets immersed into an aqueous solution of TBACl was first studied. During TPPFeCl reduction the resulting [TPPFeCl]− species is stabilized due to the excess of chloride anions inside the oil droplet. Voltammograms of homogeneous solutions of PhCN supported with TBACl show similar chemically reversible process which is also attributed to the stable [TPPFeCl]− species. This anion stabilization was not observed when the oil droplets were supported with tetrabutylammonium perchlorate (TBAP) or when the PhCN solution bathing the microdroplet ensemble was supported with TBAP resulting in a chemically irreversible process. The voltammetry of unsupported droplets immobilized on a platinum electrode immersed in different aqueous electrolytes was also explored and the fate of the [TPPFeCl]− species formed considered during the reduction sweep. Similarities and difference to voltammetry in purely homogeneous media are noted and the use of droplet voltammetry provides complimentary information.
Effects of intermediate load on damping of synchronous generator
Authors: Aree P. 
Published: February 2006

AbstractThe transfer‐function block‐diagram model of a single‐machine infinite‐bus power system, originally developed by Heffron and Phillips, has been a popular analytical tool amongst power system engineers for explanation and assessment of synchronous generator dynamic behaviors. Since this model simply accounts for the generator field circuit with none of the damper circuits, it may not always give a realistic transient response. Moreover, the model considers only a grid‐system load without local and intermediate loads. Hence, effects of these loads together with the damper circuits on electromechanical damping have not yet been completely studied. In this paper, the Heffron‐Phillips's model has been advanced to incorporate an intermediate load plus one additional damper circuit in the q‐axis. The upgraded model demonstrates a great influence of the intermediate load together with the q‐axis damper circuit on the electromechanical damping and the dynamic interaction between the field and damper flux linkages. The study shows the key contributions of load to rise and fall of the damping. It appears that the electromechanical damping can be improved with regard to the unity power‐factor load through increasing in the natural damping and decreasing in the automatic voltage regulator (AVR) negative damping torques. Nevertheless, the damping is mostly declined, when the load power factor is poor. Moreover, it is markedly changed in relation to various locations of load. The damping characteristics of synchronous generator are investigated using the eigenvalue and frequency response methods. Copyright © 2006 John Wiley & Sons, Ltd.
A new method for screening the contingencies before dynamic security assessment of a multimachine power system
Authors: Salam M. A. , Ahmed S. Shahnawaz 
Published: February 2006

AbstractThis paper proposes a novel method for identifying the faults that would impact the transient stability of a multimachine power system. In this method each synchronous machine's swing equation is formulated in the form of a closed loop transfer function in Laplace domain (s‐plane). The duration of a fault under consideration, and the changes of maximum electrical power output of the machine during and after the fault are included in the same transfer function. Then the narrowest possible range containing the real part of the ‘dominant’ root of each machine's characteristic equation is identified on the real axis of s‐plane. This is because it is the real part that decides whether the transient response would sustain or subside. If the average of the lower limits of the real parts of dominant roots for all the machines is in the left half but very close to the imaginary axis (poorly damped) or in the right half of the s‐plane (absence of damping), the system as a whole is unstable under the considered fault. The proposed method is extremely fast. An extensive digital simulation test and comparison of the proposed method with a conventional step‐by‐step (SBS) numerical integration method has been done on a 25‐machine practical system belonging to Bangladesh Power Development Board (BPDB), and good agreements observed for an array of fault scenarios. The faults for which the aforesaid average lower limit is in the left half plane but its distance from imaginary axis is marginally above or below an established minimum value, can be further investigated by a detailed time domain simulation (TDS) transient stability analysis technique. Thus the proposed method is useful for real‐time screening of the contingencies (e.g., faults) before being subjected to a full‐scale dynamic security analysis in a power system of any size with any number of machines. Copyright © 2006 John Wiley & Sons, Ltd.
Contribution to the definition of a permanent magnet motor with reduced production cost for the electrical vehicle propulsion
Authors: Neji Rafik , Tounsi Souhir , Sellami Fayçal 
Published: February 2006

AbstractThis paper deals with a methodology for the design of a permanent magnet motor dedicated for traction. Several structures to reduce the permanent magnet motor production cost are explored. The most promising is an axial flux modular structure with straight slots and concentrated windings. Optimisation procedures are presented and applied to find these structures. An analytic dimensioning step is carried out simultaneously with a finite element electromagnetic modelling step so as to validate gradually the computational analysis. Then, a fine‐tuned finite element model is realised dynamically so as to validate wave forms that depend strongly on the machine geometry as well as on the electromagnetic motor torque. This study has allowed the entire validation of the analytic sizing computations. Copyright © 2006 John Wiley & Sons, Ltd.
An efficient approach for the load‐frequency control and its role under the conditions of deregulated environment
Authors: Stojkovic Branko 
Published: February 2006

AbstractThis paper describes an specific approach to resolving problem of load frequency (LF) control in the power system of Montenegro ( Serbia and Montenegro). The complete LF controller was developed, coded, and implemented on the single PC computer ‘from the zero’ by the Company's staff in a fast, feasible, and cost‐effective manner. Its extremely high ‘in‐field’ efficiency was achieved by: the compact design of the controller, the implementation of the algorithm for efficient filtering of Control Error, the implementation of the algorithm for minimizing of the regulating units movement, as well as the feed‐back algorithm for permanent adjustment of the tie‐lines power measurements. All details on these algorithms are given. The official field results for the 6 month exploitation have confirmed the top regulating success in the Second UCTE Synchronous Zone. The Electric Power Company of Montenegro (EPCG) was recently subjected to enacting of the new Energy Law, and to the promoting of the free electricity market. So, the additional modifications were made at the AGC controller to meet the requirements of deregulation processes. Thus, the AGC system keeps track of the momentary active power imbalance, detects it, corrects it and communicates an adequate amount of the balance energy service (BES) power, on the 15‐minute basis, to the real‐time part of the market operating system (MOS), where it will be allocated to the real time market (RTM) balancing resources. Copyright © 2006 John Wiley & Sons, Ltd.
Deciphering human prehistory through the geoarcheological study of cave sediments
Authors: Goldberg Paul , Sherwood Sarah C. 
Published: February 2006

AbstractThroughout human history, caves and rockshelters have been favored habitation places. These unique environments preserve sediments derived from an assortment of geological and human processes that are typically absent or masked at open‐air sites. Cave sediments are parts of larger stratigraphic frameworks that can reflect environmental changes, shifting microenvironments, and the nature of human activity within these confined and sheltered spaces. Stone tools and faunal material compose the artifact assemblages from caves that are typically studied. Cave sediments, on the other hand, which encase the archeological finds and which have both geological and human origins, have been understudied relative to traditional artifacts, in spite of their ubiquity and importance. Thus, anthropogenic sediments, the most striking of which are organic‐rich deposits, and combustion features merit the same attention as any other artifacts that result from human activities and behaviors.The purpose of this paper is to highlight some of the most salient aspects of prehistoric cave sediments and the processes revealed by recent studies of these accumulations. We review methods and techniques that are used to analyze cave sediments and illustrate how their careful study can be used to reconstruct local and regional cave environments, as well as the nature of the human activities that produced them. Finally, we show how such study can place important constraints on our archeological interpretations, ultimately having a profound effect on how we decipher human prehistory.
Gamma stochastic volatility models
Authors: Abraham Bovas , Balakrishna N. , Sivakumar Ranjini 
Published: February 2006

AbstractThis paper presents gamma stochastic volatility models and investigates its distributional and time series properties. The parameter estimators obtained by the method of moments are shown analytically to be consistent and asymptotically normal. The simulation results indicate that the estimators behave well. The in‐sample analysis shows that return models with gamma autoregressive stochastic volatility processes capture the leptokurtic nature of return distributions and the slowly decaying autocorrelation functions of squared stock index returns for the USA and UK. In comparison with GARCH and EGARCH models, the gamma autoregressive model picks up the persistence in volatility for the US and UK index returns but not the volatility persistence for the Canadian and Japanese index returns. The out‐of‐sample analysis indicates that the gamma autoregressive model has a superior volatility forecasting performance compared to GARCH and EGARCH models. Copyright © 2006 John Wiley _ Sons, Ltd.
Non‐linear, non‐parametric, non‐fundamental exchange rate forecasting
Authors: Gradojevic Nikola , Yang Jing 
Published: February 2006

AbstractThis paper employs a non‐parametric method to forecast high‐frequency Canadian/US dollar exchange rate. The introduction of a microstructure variable, order flow, substantially improves the predictive power of both linear and non‐linear models. The non‐linear models outperform random walk and linear models based on a number of recursive out‐of‐sample forecasts. Two main criteria that are applied to evaluate model performance are root mean squared error (RMSE) and the ability to predict the direction of exchange rate moves. The artificial neural network (ANN) model is consistently better in RMSE to random walk and linear models for the various out‐of‐sample set sizes. Moreover, ANN performs better than other models in terms of percentage of correctly predicted exchange rate changes. The empirical results suggest that optimal ANN architecture is superior to random walk and any linear competing model for high‐frequency exchange rate forecasting. Copyright © 2006 John Wiley & Sons, Ltd.
Potentiation of the NMDA receptor‐mediated responses through the activation of the glycine site by microglia secreting soluble factors
Authors: Hayashi Yoshinori , Ishibashi Hitoshi , Hashimoto Kenji , Nakanishi Hiroshi 
Published: February 2006

AbstractWe have previously reported that both transferred microglia and microglia‐conditioned medium (MCM) potentiated the N‐methyl‐D‐aspatate (NMDA) receptor‐mediated synaptic responses in cortical neurons. To elucidate the mechanism underlying the potentiation of NMDA receptor‐mediated responses by microglia, we examined the effects of MCM on NMDA‐induced inward currents in mechanically dissociated hippocampal CA1 neurons under whole‐cell patch recordings. MCM potentiated the amplitude of NMDA‐induced currents up to 10‐fold in a dose‐dependent manner, and this effect of MCM remained even after boiling or cutting off molecules with a molecular mass more than 3 kDa. In the presence of glycine with a concentration sufficient to saturate the NMDA receptor glycine site, MCM failed to further potentiate the NMDA‐induced currents. The glycine site antagonist 5, 7‐dichrolokynurenic acid, significantly inhibited the effects of MCM. The effect of MCM was still observed even after treatment with D‐amino acid oxidase, a D‐serine degrading enzyme. On the other hand, MCM had no significant effect on the voltage‐dependent Mg2+ blockade of NMDA receptors. Furthermore, MCM enhanced the formation of the long‐term potentiation in the Schaffer collateral pathway‐CA1 pyramidal cell synapses. Using a high performance liquid chromatography system, we found the levels of both glycine and L‐serine in MCM to be significantly higher than those in the control medium. It was also noted that an increased glycine productivity of microglia was observed in the hippocampus in the acute phase of neuronal injury. These observations strongly suggest that glycine is a major causative molecule released from microglia that potentiates the NMDA‐induced currents. © 2006 Wiley‐Liss, Inc.
Annexin III implicated in the microglial response to motor nerve injury
Authors: Konishi Hiroyuki , Namikawa Kazuhiko , Kiyama Hiroshi 
Published: February 2006

AbstractTo identify proteins implicated in peripheral nerve regeneration, we performed two‐dimensional polyacrylamide gel electrophoresis and subsequent mass spectrometry analysis using nerve‐injured hypoglossal nuclei of rat. We have identified annexin III (ANX III/ANX A3) as an induced protein after rat hypoglossal nerve injury. ANX III is known as a Ca2+‐dependent phospholipid‐binding protein, but its physiological function is mostly unknown. By in situ hybridization and immunohistochemistry, we demonstrated that ANX III expression was induced specifically in activated (axotomy‐stimulated) microglia after nerve injury. ANX III was the most prominent ANX expressed in microglia of the major ANX family members (ANX I‐VI). Hybridization signals for other ANX mRNAs (II, IV, V, and VI) were mainly observed in neuronal cells, and no significant hybridization signal for ANX I mRNA was detected in hypoglossal nuclei. In cultured microglia, ATP treatment induced ANX III translocation to the ruffling membrane where F‐actin was accumulated. Further in vitro studies revealed that ANX III was not secreted and had F‐actin binding activity in a Ca2+‐dependent manner. These results suggest that ANX III may be a Ca2+‐dependent mediator between phospholipids and F‐actin in microglia stimulated by peripheral nerve injury. © 2006 Wiley‐Liss, Inc.
Neuronal hyperactivity induces astrocytic expression of neurocan in the adult rat hippocampus
Authors: Schwarzacher Stephan W. , Vuksic Mario , Haas Carola A. , Burbach Guido J. , Sloviter Robert S. , Deller Thomas 
Published: February 2006

AbstractExtracellular matrix molecules are involved in the cellular functions of proliferation, migration, morphological differentiation, and synaptic plasticity. One candidate molecule of the extracellular matrix is the chondroitin sulfate proteoglycan neurocan. To determine whether neurocan expression is regulated by neuronal activity in the adult rat brain, we studied changes in hippocampal neurocan mRNA and protein expression following electrical stimulation of the perforant pathway in urethane‐anesthetized rats. After 24 h of intermittent, unilateral 20 Hz stimulation, in situ hybridization revealed increased neurocan mRNA in glial fibrillary acidic protein (GFAP)‐positive astrocytes bilaterally in all hippocampal subfields. These changes were quantified in the dentate molecular layer, the termination zone of the perforant pathway, using laser microdissection in combination with quantitative reverse transcription‐polymerase chain reaction (RT‐PCR). Immediately after 24 h stimulation, a six‐fold upregulation was detected, which returned to control levels by 3 days post‐stimulation. Neurocan immunoreactivity was similarly upregulated bilaterally. Immunostaining intensity reached a maximum by 4 days and returned to control levels by 14 days. The pattern of neurocan expression in the hippocampus depended on the intensity and duration of electrical stimulation. Under conditions of less intense afferent stimulation (4–24 h of2.0 Hz paired‐pulse stimulation, interpulse interval 40 ms), increases in neurocan mRNA and immunoreactivity were restricted to the ipsilateral termination zone of the stimulated perforant pathway. This layer‐specific neurocan upregulation was not affected by intraperitoneal application of the NMDA‐receptor antagonist MK‐801. In conclusion, our data indicate that synaptic activity regulates the astrocytic expression of neurocan in a graded manner. © 2006 Wiley‐Liss, Inc.
A new method for measuring ice adhesion strength at an ice–substrate interface
Authors: Javan‐Mashmool M. , Volat C. , Farzaneh M. 
Published: February 2006

AbstractThis research focuses on the development of a direct technique for measuring atmospheric ice adhesion strength using embedded piezoelectric film sensors at the ice‐substrate interface. The substrate is a small aluminium beam on which PVDF piezoelectric sensors are bonded. The composite beam formed by aluminium and an ice layer is submitted to sinusoidal stress at the interface by a shaker on which one end of the beam is clamped. The piezoelectric charge coefficient is used to predict the electric charge density induced on the piezoelectric film, which enables us to develop a macroscopic and direct measurement technique for determining mechanical stresses at the atmospheric‐ice‐substrate interface. The preliminary results obtained show that adhesive failure was obtained for each test for a frequency close to the natural resonance frequency of the aluminium beam. Within the limitations of the experimental conditions, it was possible using this approach to obtain ice adhesion strengths in accordance with those obtained in the literature. This demonstrates the feasibility of this simple ice adhesion testing method. Copyright © 2006 John Wiley & Sons, Ltd.
Minor and trace elements as indicators of solute provenance and flow routing in a subglacial hydrological system
Authors: Mitchell Andrew C. , Brown Giles H. , Fuge Ron 
Published: February 2006

AbstractThe utility of minor and trace elements for subglacial solute‐provenance and hydrological flow‐routing studies is investigated at Haut Glacier d'Arolla (HGA), Switzerland. Principal component analysis (PCA) applied to the bulk meltwater chemistry indicates the concentration of most major ions, and some minor and trace elements (Sr, Mo, Ti) are inversely related to bulk meltwater discharge and have a clear hydrological control. Conversely, many other minor and trace elements have no clear relationship with meltwater discharge. This suggests that such solutes are affected by physico‐chemical controls such as sorption, (oxy)hydroxide formation and co‐precipitation reactions, in addition to any simple hydrological influence. PCA applied to rock digests and water‐rock interaction experiments indicates the complexity of determining the lithogenic source of minor and trace elements from subglacial chemical weathering processes. This reflects the complex aqueous mobility of many minor and trace elements and the heterogeneous geology of the HGA catchment. However, the study suggests that there is potential in minor and trace elements for solute‐provenance and flow‐routing studies in glacierized catchments underlain by a more homogeneous geology. Copyright © 2006 John Wiley & Sons, Ltd.
Accuracy assessment of MODIS daily snow albedo retrievals with in situ measurements in Karasu basin, Turkey
Authors: Tekeli Ahmet Emre , Şensoy Aynur , Şorman Arda , Akyürek Zuhal , Şorman Ünal 
Published: February 2006

AbstractOver the ablation period of 2004, daily snow albedo values retrieved from the moderate‐resolution imaging spectroradiometer (MODIS) Terra were compared with ground‐based albedo measurements. Two data sets are used for this study. The first data set is from two automatic weather stations (AWS) located at fixed points in Karasu basin in eastern Turkey. This provided the temporal assessment of MODIS daily snow albedo values. The second data set, consisting of 19 observation points randomly distributed around one of the AWS sites, enables the spatial variability assessment of MODIS albedo retrievals. Both MODIS and in situ albedo observations were aggregated in a geographic information system for further analysis.Generally, MODIS albedo values were within 10% of the in situ values. Reductions in albedo values were observed both in MODIS and field observations as snow depth decreased and snow water equivalent increased. Copyright © 2006 John Wiley & Sons, Ltd.
Instantaneous daytime conductive heat flow through snow on lake ice in Alaska
Authors: Jeffries Martin O. , Morris Kim 
Published: February 2006

AbstractThe instantaneous daytime conductive heat flow through the snow on lake ice was derived from snow depth, temperature and density measurements made during the course of six winters at MST Pond in central Alaska. The MST Pond data for winter 2003–04 are compared with results for the same period at six other sites (Barrow, Nome, Amos Lakes, Fairbanks, Wasilla, Seward) in Alaska. The maximum heat flow at MST Pond has varied between −19·5 and −8·8 W m−2. Each winter, the heat flow decreases as the total thickness of snow and ice increases with time. Superimposed on this trend are variations due to fluctuating air temperatures. The comparison of the MST Pond data with the other locations in Alaska reveals heat flow differences that reflect different weather conditions, particularly air temperature and wind, and the latter's effect on snow depth and density. Notwithstanding the regional differences, the heat flow values are of the same order of magnitude as those obtained for sea ice in the Arctic and Antarctica. The implications for the total winter conductive heat loss at large lakes and for regions where many small lakes cover a large proportion of the land are discussed. Copyright © 2006 John Wiley & Sons, Ltd.