bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation and filtering on a doubly stochastic poisson process
Authors: Valderrama Mariano J. , Jimenez Francisco , Gutierrez Ramon , Martinez‐Almecija Alfredo 
Published: May 2007

AbstractAn explicit formula for the characteristic function of a doubly stochastic Poisson process is derived in this paper by means of the harmonic decomposition of its intensity function that we suppose to be Gaussian. The statistical moments are then obtained, as well as the sample function density of the process. These results are applied to estimate the parameters of several well‐known processes. Finally, a linear filtering procedure for the intensity function is developed and the algorithm is implemented by computers.
Optimal control of dams
Authors: Abdel‐Hameed Mohamed , Nakhi Yasmin 
Published: May 2007

AbstractAssume that a dam has a capacity V. Its water input I={It, t ϵ [0, ∞)}], is assumed to be a diffusion process. The water is released at one of two rates 0 and M units of water per unit of time. The release rate is 0 until the water reaches level λ(0 < λ < V), when the water is released at rate M until it reaches level λ, (0 ≤ τ < λ). Once the level λ is reached, the release rate remains at zero until level λ is reached again, and the cycle is repeated. Under general cost structure, we discuss and review some of the most recent work in the area of optimal control of dams with release policies of the above type; we also discuss some new results and corrections to some existing results.
Optimal dynamic equilibrium in insurance policies
Authors: Page Dominique , Tremolieres Raymond 
Published: May 2007

AbstractInsurance companies sell contracts of various types each of them having a specific probability of return. Insurers may also own, at the same time, several insurance contracts which evolve through time. In this context, expectation and variance of the free reserves appear as functions of the number of customers in different classes as well as their evolution. Assuming that the customer system can be formulated as an open Markov one characterized by free entry, it is interesting to seek the optimal new customer distribution over the different customer classes j, which permits the minimization of the variance of free reserves for a desired average level of free reserves at a given time horizon. It is shown that, under some conditions, the customer system converges to an optimal growth steady state.
The effects of quantized data
Authors: Jewell William S. 
Published: May 2007

AbstractThe effects of quantized data upon parameter estimation are investigated by re‐examining a variety of simple and complicated risk models previously studied by the author. In spite of this unifying theme, no general principles arise, except for demonstrating that estimation in models with two or more parameters can lead to unpredictable results, with or without the introduction to discrete data. In fact, certain common actuarial models are shown always to have poor estimation properties, even using substantial amounts of continuous data The paper concludes with a plea for the redevelopment of classical models that are continuous in nature, rather than perpetuating the current discrete multi‐parameter models, whose estimation properties are poor, since modern technology now permits inexpensive capture of all kinds of continuous data.
Applications of risk theory and multivariate analysis in insurance practice
Authors: Niggemeyer B. , Radtke M. , Reich A. 
Published: May 2007

AbstractSegmentation strategies and differentiated preselection in underwriting call for new portfolio management techniques, the use of which is becoming increasingly widespread amongst insurance companies faced with growing competitive pressure. In recent years, mathematical procedures have been developed for this purpose and the applicability of existing procedures for use in insurance practice has been recognized. The present paper elucidates various methods for determining the aggregate claims distribution, which describes the performance and volatility of a portfolio. There then follows a presentation of multivariate methods, particularly generalized linear models and methods applying variance and discriminant analysis, which facilitate the analysis of more narrowly defined segments and subportfolios. Finally, the paper contains a description of applications used by numerous insurance companies, primarily for motor and property portfolios.
Operational time and a fundamental problem of insurance in a data‐rich environment
Authors: Reid D. H. 
Published: May 2007

AbstractA problem of current concern in the assessment of claims experience in non‐life insurance is addressed. The problem relates to the interface of two well‐defined areas of actuarial activity, namely reserving and rating. A model is proposed that permits the analysis of claim settlement experience in such a way as to allow for variations in settlement rate, proportions of nil claims and variations from year to year in a risk‐factorial background. From this, the reserving approach may be developed coherently into the area of risk costing for rating purposes.
Stochastic modelling of household behaviour before, during and after a consumer price promotion
Authors: Takada Hirokazu , Chen Yu‐Min 
Published: May 2007

AbstractA stochastic model is developed to study household behaviour with regard to purchase quantity, brand choice and purchase timing before, during and after a price change and a price promotion such as price‐offs and price‐cuts. The basic assumption of the model is that price promotion and levels of consumer inventory influence a household's purchase‐timing and brand‐switching decisions. The model incorporates market segments and brand switching on aggregated demand for the brands by the use of multivariate Markov processes. A transient stochastic model is employed to analyse the dynamic process of household behaviour before, during, and after a price promotion. The interpurchase time that is derived from the model does not require any assumptions and is not independently, identically distributed. An empirical analysis using the Information Resources Incorporated cracker data indicated that (1) price promotion does affect household purchase of the brand and (2) households with larger family size tend to purchase promoted items. We conjecture that households with larger family size take advantage of the lower price of the promoted brands while smaller households tend to remain loyal to one brand.
Biotin‐related abnormalities in human metabolism
Authors: Nyhan William L. 
Published: May 2007

AbstractRecent work has led to the discovery that two severe hereditary human pathologies are caused by biotin deficiency. Significantly, administration of pharmacologic doses of biotin can provide clinically effective treatment. Both diseases are autosomal recessive in inheritance but differ in their associated enzymatic deficiencies. The clinical, enzymatic, and genetic characteristics of these pathologies are reviewed here.
Conformational solution studies of the SDS micelle‐bound 11‐28 fragment of two Alzheimer's β‐amyloid variants (E22K and A21G) using CD, NMR, and MD techniques
Authors: Rodziewicz‐Motowidło Sylwia , Juszczyk Paulina , Kołodziejczyk Aleksandra S. , Sikorska Emilia , Skwierawska Agnieszka , Oleszczuk Marta , Grzonka Zbigniew 
Published: May 2007

AbstractThe β‐amyloid (Aβ) is the major peptide constituent of neuritic plaques in Alzheimer's disease (AD) and its aggregation is believed to play a central role in the pathogenesis of the disease. Naturally occurring mutations resulting in changes in the Aβ sequence (pos. 21‐23) are associated with familial AD‐like diseases with extensive cerebrovascular pathology. It was proved that the mutations alter the aggregation ability of Aβ and its neurotoxicity. Among five mutations at positions 21–23 there are two mutations with distinct clinical characteristics and potentially distinct pathogenic mechanism—the Italian (E22K) and the Flemish (A21G) mutations. In our studies we have examined the structures of the 11‐28 fragment of the Italian and Flemish Aβ variants. The fragment was chosen because it has been shown to be the most important for amyloid fibril formation. The detailed structure of both variants Aβ(11‐28) was determined using CD, 2D NMR, and molecular dynamics techniques under water‐SDS micelle conditions. The NMR analysis revealed two distinct sets of proton resonances for the peptides. The studies of both peptides pointed out the existence of well‐defined α‐helical conformation in the Italian mutant, whereas the Flemish was found to be unstructured with the possibility of a bent structure in the central part of the peptide. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 23–39, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Der Einfluß verschiedener politischer Systeme auf Ungarns Wissenschaft im 20. Jahrhundert
Authors: Szabadváry Ferenc 
Published: May 2007

AbstractWÄRE ICH IM JAHRE 1823 in Ungarn geboren worden und hätte man mich vor 100 Jahren, also 1896, gefragt, wie die Politik meine naturwissenschaftlichen Forschungen beeinflußt habe, so hätte ich erstaunt geantwortet: Wieso diese Frage, was haben denn die beiden miteinander zu tun?
Associations ofABCB1, ABCC2, andABCG2polymorphisms with irinotecan‐pharmacokinetics and clinical outcome in patients with advanced non‐small cell lung cancer
Authors: Han Ji‐Youn , Lim Hyeong‐Seok , Yoo Yeon‐Kyeong , Shin Eun Soon , Park Yong Hoon , Lee Sung Young , Lee Jong‐Eun , Lee Dea Ho , Kim Heung Tae , Lee Jin Soo 
Published: May 2007

AbstractBACKGROUND.The authors investigated whetherABCB1, ABCC2,andABCG2genetic polymorphisms affect pharmacokinetics (PK) of irinotecan and treatment outcome of patients with advanced nonsmall cell lung cancer (NSCLC).METHODS.Blood samples from 107 NSCLC patients treated with irinotecan and cisplatin chemotherapy were used for genotypingABCB1(1236C > T, 2677G > T/A, 3435C > T),ABCC2(−24C > T, 1249G > A, 3972C > T), andABCG2(34G > A, 421C > A) polymorphisms. Genotypes were correlated with irinotecan‐PK, toxicity, tumor response, and survival.RESULTS.Among 8 polymorphisms, 3435TT and 2677TT were associated with AUCSN‐38Gand CLSN‐38G. When haplotypes are assigned, 2677TT/3435TT carriers showed significantly lower AUCSN‐38G(P= .006), whereas 2677GG/3435CC carriers showed significantly higher AUCSN‐38(P= .039). These findings suggest that 2677TT and 3435TT variants are associated with higher efflux activity. In toxicity, the 2677G/T or A was associated with grade 4 neutropenia. The 2677GG carriers showed significantly lower absolute neutrophil count during the 1stcycle (P= .012) as well as entire course of chemotherapy (P= .042). The 3435TT was associated with higher frequency of grade 3 diarrhea (P= .047). In tumor response,ABCC2−24TT and 3972TT genotypes were associated with higher response rates (P= .031 and .046, respectively) and longer progression‐free survival (P= .035 and .038, respectively), which was sustained in haplotype analysis.CONCLUSIONS.Specific polymorphisms ofABCB1andABCC2can influence disposition and tumor response to irinotecan by regulating transporter activity. These findings may help to individualize irinotecan‐based chemotherapy in patients with advanced NSCLC. Cancer 2007. © 2007 American Cancer Society.
Fused Donor–Acceptor Ligands in RuII Chemistry: Synthesis, Electrochemistry and Spectroscopy of [Ru(bpy)3−n(TTF‐dppz)n](PF6)2
Authors: Goze Christine , Leiggener Claudia , Liu Shi‐Xia , Sanguinet Lionel , Levillain Eric , Hauser Andreas , Decurtins Silvio 
Published: May 2007

AbstractThree ruthenium(II) polypyridine complexes of general formula [Ru(bpy)3−n(TTF‐dppz)n](PF6)2 (n=1‐3, bpy=2,2′‐bipyridine), with one, two or three redox‐active TTF‐dppz (4′,5′‐bis(propylthio)tetrathiafulvenyl[i]dipyrido[3,2‐a:2′,3′‐c]phenazine) ligands, were synthesised and fully characterised. Their electrochemical and photophysical properties are reported together with those of the reference compounds [Ru(bpy)3](PF6)2, [Ru(dppz)3](PF6)2 and [Ru(bpy)2(dppz)](PF6)2 and the free TTF‐dppz ligand. All three complexes show intraligand charge‐transfer (ILCT) fluorescence of the TTF‐dppz ligand. Remarkably, the complex with n=1 exhibits luminescence from the Ru2+→dppz metal‐to‐ligand charge‐transfer (3MLCT) state, whereas for the other two complexes, a radiationless pathway via electron transfer from a second TTF‐dppz ligand quenches the 3MLCT luminescence. The TTF fragments as electron donors thus induce a ligand‐to‐ligand charge‐separated (LLCS) state of the form TTF‐dppz−‐Ru2+‐dppz‐TTF+. The lifetime of this LLCS state is approximately 2.3 μs, which is four orders of magnitude longer than that of 0.4 ns for the ILCT state, because recombination of charges on two different ligands is substantially slower.
Syntheses, Structures and Coordination Modes of Acetatopalladium(II) Complexes with 1,3‐Bis(2‐arylimino)isoindoline Ligands of Different Steric Influence
Authors: Bröring Martin , Kleeberg Christian , Cónsul Tejero Esther 
Published: May 2007

AbstractAcetatopalladium(II) complexes of four different 1,3‐bis(2‐arylimino)isoindoline ligands (bai's) with different degrees of steric congestion have been prepared and were characterized by NMR and XRD with respect to nuclearity and coordination mode. In particular, the propensity for heteroaryl ring rotation and C–H activation has been investigated. Palladium(II) ions bind to bai ligands in different coordination modes, either as classical Werner‐type N,N,N bonded complexes or―after pyridyl ring rotation and C–H activation―as carbometalated C,N,N chelates. In the latter case two (bai*)Pd(OAc) subunits have been found to dimerize via two bridging Pd(OAc) moieties in the solid and in solution. These stable and electroneutral tetranuclear species are of low solubility in non‐donor solvents, but break up into soluble dinuclear species of unknown composition upon the addition of DMSO, azide or cyanide. Attempts to activate C–C bonds by this strategy were not successful. Surprisingly, the exchange of the terminal pyridines by pyrimidines does not result in the formation of oligonuclear or oligomeric species. Besides the degree of steric hindrance, three more factors, solubility of the products, stoichiometry of metal precursor and charge compensation, have been identified to govern the outcome of the metalation of these bai ligands.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Simple Synthesis of 6‐(Trifluoromethyl)‐2,4,5,6‐tetrahydropyrazolo[3,4‐b]pyran Derivatives by One‐Pot, Three‐Component Reactions
Authors: Li Dong‐Mei , Song Li‐Ping , Li Xian‐Fu , Xing Chun‐Hui , Peng Wei‐Min , Zhu Shi‐Zheng 
Published: May 2007

AbstractOne‐pot, three‐component condensation reactions of aromatic aldehydes 1, 3‐methylpyrazol‐5‐one (2) and ethyl trifluoroacetoacetate (3) provided an efficient methodology for the preparation of ethyl (4S*,5R*)‐4‐aryl‐6‐hydroxy‐3‐methyl‐6‐(trifluoromethyl)‐2,4,5,6‐tetrahydropyrazolo[3,4‐b]pyran‐5‐carboxylate derivatives (4). The reactions gave moderate to good yields under mild conditions. These new products 4 were fully characterized by spectral methods and single‐crystal X‐ray diffraction analysis. A plausible reaction pathway for the formation of 4 is presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Estimating the cost‐effectiveness of an intervention in a clinical trial when partial cost information is available: a Bayesian approach
Authors: Lambert Paul C. , Billingham Lucinda J. , Cooper Nicola J. , Sutton Alex J. , Abrams Keith R. 
Published: May 2007

AbstractThere is an increasing need to establish whether health‐care interventions are cost effective as well as clinically effective. It is becoming increasingly common for cost studies to be incorporated into clinical trials, either on all patients or more usually on a subset of patients. Establishing the total cost per patient is complex, as it requires information on resource use, which may come from a variety of different sources. This complexity may lead to considerable missing data, and can result in some patients only having partial cost information.In this paper we consider a clinical trial consisting of 351 patients with advanced non‐small cell lung cancer comparing chemotherapy with standard palliative care. A subset of 115 patients was selected for the cost sub‐study. Total cost was split into four components, for which resource use was collected. Complete resource data were available on 82 patients. For the remaining patients at least one of the cost components was missing.The objective of this paper is to develop a Bayesian approach which simultaneously models both the clinical effectiveness data and the cost data, by modelling the individual components. This also provides estimates of the cost‐effectiveness in terms of the Incremental Net Monetary Benefit (INMB) and Cost‐Effectiveness Acceptability Curves (CEAC). We compare a number of different models of increasing complexity. The models estimate the interrelationships between the four cost components and survival, and thus enable a predictive distribution for each missing cost item to be obtained. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of canopy density on snow distribution in a temperate mountain range
Authors: López‐Moreno J. I. , Latron J. 
Published: May 2007

AbstractWe analyse spatial variability and different evolution patterns of snowpack in a mixed beech–fir stand in the central Pyrenees. Snow depth and density were surveyed weekly along six transects of contrasting forest cover during a complete accumulation and melting season; we also surveyed a sector unaffected by canopy cover. Forest density was measured using the sky view factor (SVF) obtained from digital hemispherical photographs. During periods of snow accumulation and melting, noticeable differences in snow depth and density were found between the open site and those areas covered by forest canopy. Principal component analysis provided valuable information in explaining these observations. The results indicate a high variability in snow accumulation within forest areas related to differences in canopy density. Maximum snow water equivalent (SWE) was reduced by more than 50% beneath dense canopies compared with clearings, and this difference increased during the melting period. We also found significant temporal variations: when melting began in sectors with low SVF, most of the snow had already thawed in areas with high SVF. However, specific conditions occasionally produced a different response of SWE to forest cover, with lower melting rates observed beneath dense canopies. The high values of correlation coefficients for SWE and SVF (r > 0·9) indicate the reliability of predicting the spatial distribution of SWE in forests when only a moderate number of observations are available. Digital hemispherical photographs provide an appropriate tool for this type of analysis, especially for zenith angles in the range 35–55 . Copyright © 2007 John Wiley & Sons, Ltd.
Estimating nutrient and sediment flood loads in a small Mediterranean river
Authors: Salles Christian , Tournoud Marie George , Chu Yin 
Published: May 2007

AbstractVarious methods were evaluated for estimating the loads of total suspended sediments and particulate associated and dissolved nutrients during floods. The six selected methods were compared using field data from two carefully sampled floods at the outlet of a small Mediterranean catchment. Water samples were available during floods at short time intervals (i.e. from 1 to 6 h time steps) and discharge was measured every 5 min. In the first step, the load estimators were compared on the basis of available data. Despite a fine description of the species concentration, there were significant differences in load estimates between the six methods. In the second step the sampling sensitivity of the methods was compared. For the two floods, 3000 random sub‐samples were generated from Monte Carlo simulations. The estimates derived from the random sub‐samples were compared to the load estimated by using the entire record. The results show that bias and precision are affected by the sample size and the transport phase of the species. Generally speaking, two methods allow reliable load estimation as long as a detailed water flow and at least three to four samples per day are available. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of seasonal local recharge using electrical resistivity tomography and magnetic resonance sounding
Authors: Descloitres Marc , Ruiz Laurent , Sekhar M. , Legchenko Anatoly , Braun Jean‐Jacques , Mohan Kumar M. S. , Subramanian S. 
Published: May 2007

AbstractA groundwater recharge process of heterogeneous hard rock aquifer in the Moole Hole experimental watershed, south India, is being studied to understand the groundwater flow behaviour. Significant seasonal variations in groundwater level are observed in boreholes located at the outlet area indicating that the recharge process is probably taking place below intermittent streams. In order to localize groundwater recharge zones and to optimize implementation of boreholes, a geophysical survey was carried out during and after the 2004 monsoon across the outlet zone. Magnetic resonance soundings (MRS) have been performed to characterize the aquifer and measure groundwater level depletion. The results of MRS are consistent with the observation in boreholes, but it suffers from degraded lateral resolution. A better resolution of the regolith/bedrock interface is achieved using electrical resistivity tomography (ERT). ERT results are confirmed by resistivity logging in the boreholes. ERT surveys have been carried out twice—before and during the monsoon—across the stream area. The major feature of recharge is revealed below the stream with a decrease by 80% of the calculated resistivity. The time‐lapse ERT also shows unexpected variations at a depth of 20 m below the slopes that could have been interpreted as a consequence of a deep seasonal water flow. However, in this area time‐lapse ERT does not match with borehole data. Numerical modelling shows that in the presence of a shallow water infiltration, an inversion artefact may take place thus limiting the reliability of time‐lapse ERT. A combination of ERT with MRS provides valuable information on structure and aquifer properties respectively, giving a clue for a conceptual model of the recharge process: infiltration takes place in the conductive fractured‐fissured part of the bedrock underlying the stream and clayey material present on both sides slows down its lateral dissipation. Copyright © 2007 John Wiley & Sons, Ltd.