bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Levoglucosan and Related Steroisomers in Fog Water as a Biomass Combustion Tracer by ESI‐MS/MS
Authors: Palma Pierangela , Cappiello Achille , de Simoni Elisa , Mangani Filippo , Trufelli Helga , Decesari Stefano , Facchini Maria Cristina , Fuzzi Sandro 
Published: November 2004

AbstractA conspicuous fraction of the water soluble organic compounds (WSOC) in fog and fine aerosol samples is composed by monosaccharide anhydrides, such as levoglucosan and its stereoisomers, galactosan and mannosan. Levoglucosan is produced exclusively during wood combustion processes, making it a very useful tracer for plant combustion emissions in the atmosphere. This paper describes a new experimental approach, based on electrospray‐tandem mass spectrometry (ESIMS/ MS), for the identification of levoglucosan in fog water samples. The analytical method proposed allows to identify the specific sugar anhydrides directly in the liquid phase without the need of any derivatization process.
Validation of LC/MS Electrospray Ionisation Method for the Estimation of Ursodiol in Human Plasma and ITS Application in Bioequivalence STUDY
Authors: Sundd Singh Sonu , Shah Hiten , Gupta Sapna , Jain Manish , Sharma Kuldeep , Patel Harshvardhan , Shah Bhavin , Thakkar Purav , Patel Nimesh , Shah Ruchy , Bhushan Lohary Braj 
Published: November 2004

AbstractA novel High Performance Liquid Chromatography — electrospray mass spectrometric method has been developed for the estimation of Ursodiol (Ursodeoxycholic acid)‐a bile acid, in human plasma using Ornidazole as internal standard. The methodology involved solid phase extraction of the analyte from human plasma matrix. The chromatographic separation was achieved within seven minutes by an isocratic mobile phase containing 1.0 mM ammonium acetate and Acetonitrile (65: 35, v/v), flowing through XTerra MS C18, 100 × 2.1, 3.5 μm analytical column, at a flow rate of 0.2 ml/min. Ion signals were measured in negative mode for Ursodiol and internal standard at m/z 391.3 and 278.1, respectively. A detailed validation of the method was performed as per USFDA guidelines and the standard curves were found to be linear in the range 50.0 ng/ml to 3000.0 ng/ml with the mean correlation coefficient more than 0.99. The absolute recovery was more than 54.90 % for Ursodiol and 76.51 % for internal standard. Ursodiol was stable for sixty‐nine days at −70 °C and for eight hours at ambient temperature. After extraction from plasma, the reconstituted samples of Ursodiol were stable in autosampler at 10 °C for forty‐eight hours. Upon subjecting to three freeze thaw cycles, there was no change in the recovery of the analyte. The integrity of the plasma samples remained unaffected even upon four‐fold dilution with drug free human plasma. The method was simple, specific, sensitive, precise, accurate and suitable for bioequivalence and pharmacokinetic studies. It was successfully applied to the pilot bioequivalence study of Ursodiol in male human subjects.
What do we know about apolipoprotein E and the prevention of cardiovascular disease?
Authors: Tan Chee‐Eng , Tai E. Shyong 
Published: November 2004

AbstractApolipoprotein E (ApoE) serves as a ligand for low‐density lipoprotein (LDL) receptor and LDL receptor–related protein and plays an important role in the clearance of triglyceride‐rich lipoproteins. The links between ApoE and cardiovascular disease has been shown in animal models and numerous epidemiological studies. Deletion of the APOE gene in mice resulted in high plasma cholesterol and spontaneous atherosclerosis. Atheroma formation in APOE‐deficient mice can be prevented by expression of ApoE through various genetic transfer techniques. These effects may be independent of the effect on cholesterol levels, suggesting a direct antiatherogenic effect of ApoE. In humans, the APOE genotypes are important determinants of LDL‐C and were highest in subjects with the ϵ4 allele, intermediate in ϵ3 subjects, and lowest in ϵ2 subjects. Targeting APOE expression or ApoE levels represents an attractive means of reversing or preventing atherosclerosis. Infusion of recombinant adenovirus containing ApoE, intramuscular injection of plasmid vector encoding for APOE3 cDNA, or infusion of recombinant ApoE in animal models have all resulted in reduction in cholesterol and prevention of atherosclerosis. The use of peptide models of ApoE in animals has also shown some potential in reducing atherosclerosis. However, the short half‐lives of recombinant ApoE or its peptide models are a limitation to their usefulness. New modalities for drug delivery that allow sustained delivery of ApoE, such as the multivesicular liposome depot‐delivery system (DepoFoam) may pave the way for the use of ApoE as a means of therapy in atherosclerosis prevention. Interactions between APOE genotypes and response to lipid‐lowering therapy is another area of focus when considering the role of ApoE in the prevention of atherosclerosis. Drug Dev. Res. 62:200–206, 2004. © 2004 Wiley‐Liss, Inc.
Pharmacogenomics of the p53 tumor suppressor and its role in cancer chemoresistance
Authors: Liu Suxing , Bishop W. Robert , Dasmahapatra Bimal , Wang Yaolin 
Published: November 2004

AbstractDrug resistance remains a key obstacle to successful cancer treatment. The implementation of pharmacogenomics is widely proclaimed as a route to revolutionize the face of cancer therapy. Here we discuss the pharmacogenomics of the p53 tumor suppressor and its role in cancer chemosensitivity. It has been proposed that p53 has a profound impact on the response to chemotherapy and participates in development of drug resistance in tumor cells. This is based on the dual role of p53 as a guardian of genome integrity and as a key mediator of apoptosis. Alterations of the p53 gene occur in approximately 50% of human cancer, and human tumor cells retaining wild‐type p53 often have epigenetic defects in the p53 pathway. Extensive mechanistic studies of drug action suggest that virtually all cancer cells have a dysfunctional p53 system (including p53 and its associated proteins, both upstream regulators and downstream targets). Various experimental approaches to correct the p53 pathway defects in tumor cells are discussed. Many studies have correlated p53 status with prognosis and therapy response in tumors. However, the impact of p53 status on drug resistance of tumors is still controversial. The impact of p53 on chemosensitivity is complex and multifactorial, depending on the genotypic/phenotypic context of the cell. Recent technological achievements have fostered a renewed interest in pharmacogenomics of p53 and its association with drug response. These include high‐throughput tissue microarray analysis of p53 protein expression, single nucleotide polymorphism genotyping of the p53 gene, and gene expression profiling to identify the gene signature of p53‐associated chemoresistance. Knowledge from pharmacogenomic studies will provide an opportunity for improvements in drug efficacy through effective stratification of patients, and early identification of those individuals most likely to respond effectively to a specific therapy. Drug Dev. Res. 62:254–272, 2004. © 2004 Wiley‐Liss, Inc.
Incorporating uncertainty in chemical process design for environmental risk assessment
Authors: Vasquez Victor R. , Whiting Wallace B. 
Published: November 2004

AbstractThe effects of uncertainty in thermophysical properties on the evaluation of the environmental performance is demonstrated with a chemical process to recover toluene and ethyl acetate by absorption from a gaseous waste stream of a cellophane production plant. In this case study, the environmental performance is defined as the estimation of the volatile organic compounds (VOCs) and total emissions of the plant and of several environmental risk indexes. We found that estimations of VOCs are very sensitive to uncertainty in thermophysical properties such as infinite‐dilution activity coefficients, and vapor pressures (through uncertain temperature variations). Additionally, we concluded that calculation of the total emissions can be very sensitive to fuel content factors such as those used to estimate greenhouse gases. This can have such an impact on the emission calculations that a detailed model of the given chemical process might not be required for the estimation of the total emissions. In other words, a simpler process flowsheet model can perform the same task just as well, with the results within the variations caused by uncertainty in the thermophysical properties. We demonstrate a Monte Carlo approach that allows the detection of such uncertainty characteristics in a design, providing a rational basis for prediction of the associated environmental risks. This procedure also enables the deconvolution of various sources of uncertainty, and the estimation of physical property uncertainty through a similarity approach. We concluded that our framework can be used to enhance decision making by uncovering uncertainties and sensitivities in chemical process simulation. © 2004 American Institute of Chemical Engineers Environ Prog, 2004
Cache replacement policies for P2P file sharing protocols
Authors: Wierzbicki Adam , Leibowitz Nathaniel , Ripeanu Matei , Woźniak Rafał 
Published: November 2004

AbstractPeer‐to‐peer (P2P) file‐sharing applications generate a large part of today's Internet traffic. The large volume of this traffic (thus high potential caching benefits) and the large cache sizes required (thus non‐trivial costs associated with caching) only underline that efficient cache replacement policies are important in this case. File popularity in P2P file‐sharing networks does not follow Zipf's law and several additional characteristics set the generated traffic apart from well‐studied Web traffic. All this lead us to conduct a focused study of efficient cache management policies for P2P file‐sharing traffic. This paper uses real‐world traces and trace driven simulations to compare traditional cache replacement policies and new policies that exploit characteristics of the P2P file‐sharing traffic generated by applications using FastTrack protocol. Copyright © 2004 AEI
Experimental analysis of the impact of peer‐to‐peer applications on traffic in commercial IP networks
Authors: Ben Azzouna Nadia , Guillemin Fabrice 
Published: November 2004

AbstractTo evaluate the impact of peer‐to‐peer (P2P) applications on traffic in wide area networks, we analyze measurements from a high speed IP backbone link carrying TCP traffic towards several ADSL areas. The first observations are that the prevalent part of traffic is due to P2P applications (almost 80% of total traffic) and that the usage of network becomes symmetric in the sense that customers are not only clients but also servers. This latter point is observed by the significant proportion of long flows mainly composed of ACK segments. When analyzing the bit rate created by long flows, it turns out that the TCP connections due to P2P applications have a rather small bit rate and that there is no evidence for long range dependence. These facts are intimately related to the way P2P protocols are running. We separately analyze signaling traffic and data traffic. It turns out that by adopting a suitable level of aggregation, global traffic can be described by means of usual tele‐traffic models based on M/G/∞ queues with Weibullian service times. Copyright © 2004 AEI
An analytic model for the behavior of arbitrary peer‐to‐peer networks
Authors: Schollmeier Rüdiger , Schollmeier Gero 
Published: November 2004

AbstractWe present an analytic approach to better understand and design peer‐to‐peer (P2P) networks, which are becoming increasingly important, as they contribute an amount of traffic often dominating the total traffic in the internet even today. We start from a graph theoretical approach for infinite random networks and enhance that to include the effects of a finite network. Our approach is valid for an arbitrary degree distribution in the network and thus avoids the need for extensive simulation, which would otherwise be required to evaluate the performance of a specific P2P protocol. Our analytic approach can thus be used for improved tailoring of P2P communication as well as to minimize the often excessive signaling traffic. Copyright © 2004 AEI
Forecasting futures returns in the presence of price limits
Authors: Harel Arie , Harpaz Giora , Yagil Joseph 
Published: November 2004

AbstractIn a futures market with a daily price‐limit rule, trading occurs only at prices within limits determined by the previous day's settlement price. Price limits are set in dollars but can be expressed as return limits. When the daily return limit is triggered, the true equilibrium futures return (and price) is unobservable. In such a market, investors may suffer from information loss if the return “moves the limit.” Assuming normally distributed futures returns with unknown means but known volatilities, we develop a Bayesian forecasting model in the presence of return limits and provide some numerical predictions. Our innovation is the derivation of the predictive density for futures returns in the presence of return limits. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:199–210, 2005
Traders' strategic behavior in an index options market
Authors: Shik Eom Kyong , Buhm Hahn Sang 
Published: November 2004

AbstractWe analyze traders' strategic behavior in an index options market, examining the relationships among expected duration, frequency of trades, trade size, and time to maturity using a modified ACD model. Using intraday data at‐the‐money put and call options, we obtain the following results: (1) Frequency of trades contains more information about future option price volatility than does trade size. This may result from institutional or large traders who have issued naked options using the delta‐neutral strategy to hedge those options. This also suggests that informed traders use their informational advantage little by little, rather than all at once. (2) Option volatility increases as the maturity date approaches, contradicting the prediction of the Black‐Scholes model. (3) The duration of the previous interval has a persistent effect on expected duration of the current interval. (4) For the estimation of the modified ACD model, the standardized distribution of duration is Weibull with γ < 1, not exponential. (5) The duration in the options market exhibits an inverse U‐shaped diurnal pattern, much like that of the U.S. stock market. However, unlike in the U.S. stock market, the index options duration becomes much shorter right before lunch hour (12:00 pm). © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:105–133, 2005
Incorporating topographic variability into a simple regional snowmelt model
Authors: Sloan W. T. , Kilsby C. G. , Lunn R. 
Published: November 2004

AbstractGeneral circulation models (GCMs), or stand‐alone models that are forced by the output from GCMs, are increasingly being used to simulate the interactions between snow cover, snowmelt, climate and water resources. The variation in snowpack extent, and hence albedo, through time in a cell is likely to be substantial, especially in mid‐latitude mountainous regions. As a consequence, the energy budget simulation by a GCM relies on a realistic representation of snowpack extent. Similarly, from a water resource perspective, the spatial extent of the pack is key in predicting meltwater discharges into rivers. In this paper a simple computationally efficient regional snow model has been developed, which is based on a degree‐day approach and simulates the fraction of the model domain covered by snow, the spatially averaged melt rate and the mean snowpack depth. Computational efficiency is achieved through a novel spatial averaging procedure, which relies on the assumptions that precipitation and temperature scale linearly with elevation and that the distribution of elevations in the domain can be modelled by a continuous function. The resulting spatially averaged model is compared with both observations of the duration of snow cover throughout Austria and with results from a distributed model based on the same underlying assumptions but applied at a fine spatial resolution. The new spatially averaged model successfully simulated the seasonal snow duration observations and reproduced the daily dynamics of snow cover extent, the spatially averaged melt rate and mean pack depth simulated by the distributed model. It, therefore, offers a computationally efficient and easily applied alternative to the current crop of regional snow models. Copyright © 2004 John Wiley & Sons, Ltd.
Hydrological model sensitivity to parameter and radar rainfall estimation uncertainty
Authors: Hossain Faisal , Anagnostou Emmanouil N. , Dinku Tufa , Borga Marco 
Published: November 2004

AbstractRadar estimates of rainfall are being increasingly applied to flood forecasting applications. Errors are inherent both in the process of estimating rainfall from radar and in the modelling of the rainfall–runoff transformation. The study aims at building a framework for the assessment of uncertainty that is consistent with the limitations of the model and data available and that allows a direct quantitative comparison between model predictions obtained by using radar and raingauge rainfall inputs. The study uses radar data from a mountainous region in northern Italy where complex topography amplifies radar errors due to radar beam occlusion and variability of precipitation with height. These errors, together with other error sources, are adjusted by applying a radar rainfall estimation algorithm. Radar rainfall estimates, adjusted and not, are used as an input to TOPMODEL for flood simulation over the Posina catchment (116 km2). Hydrological model parameter uncertainty is explicitly accounted for by use of the GLUE (Generalized Likelihood Uncertainty Estimation). Statistics are proposed to evaluate both the wideness of the uncertainty limits and the percentage of observations which fall within the uncertainty bounds. Results show the critical importance of proper adjustment of radar estimates and the use of radar estimates as close to ground as possible. Uncertainties affecting runoff predictions from adjusted radar data are close to those obtained by using a dense raingauge network, at least for the lowest radar observations available. Copyright © 2004 John Wiley & Sons, Ltd.
Complex wavelets for extended depth‐of‐field: A new method for the fusion of multichannel microscopy images
Authors: Forster Brigitte , Van De Ville Dimitri , Berent Jesse , Sage Daniel , Unser Michael 
Published: November 2004

AbstractMicroscopy imaging often suffers from limited depth‐of‐field. However, the specimen can be “optically sectioned” by moving the object along the optical axis. Then different areas appear in focus in different images. Extended depth‐of‐field is a fusion algorithm that combines those images into one single sharp composite. One promising method is based on the wavelet transform. Here, we show how the wavelet‐based image fusion technique can be improved and easily extended to multichannel data. First, we propose the use of complex‐valued wavelet bases, which seem to outperform traditional real‐valued wavelet transforms. Second, we introduce a way to apply this technique for multichannel images that suppresses artifacts and does not introduce false colors, an important requirement for multichannel optical microscopy imaging. We evaluate our method on simulated image stacks and give results relevant to biological imaging. Microsc. Res. Tech. 65:33–42, 2004. © 2004 Wiley‐Liss, Inc.
Evidence that rehydrated, lyophilized red blood cells are sufficiently deformable for normal microcirculation transit
Authors: Fischer Thomas H. , Robbins Mary E. , Bode Arthur P. , Nichols Timothy C. , Bellinger Dwight E. , Schoenfisch Mark H. 
Published: November 2004

AbstractA method was developed for the preparation of rehydratable lyophilized red blood cells (RL RBCs) that hold promise as cell‐based oxygen carriers for transfusion medicine. The maintenance of normal cellular deformability is essential for the successful development of cell‐based oxygen delivery systems. Improper deformability of RBCs can lead to hemolysis if too fragile or microvascular occlusion if too rigid. We developed an aldehyde stabilization method that is based on the use of paraformaldehyde polymers that complement the function of spectrin as a structural unit with conformational flexibility. Three types of in vitro deformability studies (filter transit, pipette aspiration, and atomic force microscopy) and in vivo intravital microscopy were performed to characterize the deformability of RL RBCs. When considered with safety data from previously reported studies in dogs, the results of these studies indicate that paraformaldehyde‐modified RL RBCs have visco‐elastic deformability properties that are in the nonpathological range. Microsc. Res. Tech. 65:62–71, 2004. © 2004 Wiley‐Liss, Inc.
Terminal nerve and vision
Authors: Behrens U. , Wagner H.‐J. 
Published: November 2004

AbstractThe vertebrate retina receives efferent input from different parts of the central nervous system. Efferent fibers are thought to influence retinal information processing but their functional role is not well understood. One of the best‐described retinopetal fiber systems in teleost retinae belongs to the terminal nerve complex. Gonadotropin‐releasing hormone (GnRH) and molluscan cardioexcitatory tetrapeptide (FMRFamide)‐containing fibers from the ganglion of the terminal nerve form a dense fiber plexus in the retina at the border of the inner nuclear and inner plexiform layer. Peptide‐containing fibers surround and contact perikarya of dopaminergic interplexiform cells in teleost retina. In vitro experiments demonstrated that exogenously supplied GnRH mediates dopaminergic effects on the membrane potential and on the morphology of dendritic tips (spinules) of cone horizontal cells. These effects can be specifically blocked by GnRH‐antagonists, indicating that the release of dopamine and dopamine‐dependent effects on light adaptation of retinal neurons are affected by the terminal nerve complex. Recent data have shown that olfactory information has an impact on retinal physiology, but its precise role is not clear. The efferent fiber of the terminal nerve complex is one of the first retinopetal fiber systems for which the sources of the fibers, their cellular targets, and several physiological, morphological, and behavioral effects are known. The terminal nerve complex is therefore a model system for the analysis of local information processing which is influenced by a distinct fiber projection. Microsc. Res. Tech. 65:25–32, 2004. © 2004 Wiley‐Liss, Inc.
Automatic segmentation of diatom images for classification
Authors: Jalba Andrei C. , Wilkinson Michael H.F. , Roerdink Jos B.T.M. 
Published: November 2004

AbstractA general framework for automatic segmentation of diatom images is presented. This segmentation is a critical first step in contour‐based methods for automatic identification of diatoms by computerized image analysis. We review existing results, adapt popular segmentation methods to this difficult problem, and finally develop a method that substantially improves existing results. This method is based on the watershed segmentation from mathematical morphology, and belongs to the class of hybrid segmentation techniques. The novelty of the method is the use of connected operators for the computation and selection of markers, a critical ingredient in the watershed method to avoid over‐segmentation. All methods considered were used to extract binary contours from a large database of diatom images, and the quality of the contours was evaluated both visually and based on identification performance. Microsc. Res. Tech. 65:72–85, 2004. © 2004 Wiley‐Liss, Inc.