bluuebunny/crossref_metadata_2025_split huggingface dataset:
The assimilation of AIRS radiance data at ECMWF
Authors: Mcnally A. P. , Watts P. D. , A. Smith J. , Engelen R. , Kelly G. A. , Thépaut J. N. , Matricardi M. 
Published: June 2006

AbstractThe development of an assimilation system for radiance data from the Atmospheric InfraRed Sounder (AIRS) is described, in particular the identification of cloud contamination, bias correction and the characterization of errors in the measured radiances and radiative‐transfer model. The results of assimilation experiments are presented. These show that a conservative use of AIRS radiance data (in a system already extensively observed with other satellite data) results in a small, but consistent, improvement in the quality of analyses and forecasts. Larger impacts of AIRS are found in hypothetical experiments that test the use of radiances from only a single sounding instrument. In these, the use of AIRS is found to outperform the use of data either from a single Advanced Microwave Sounding Unit‐A (AMSU‐A) or from a single High‐resolution InfraRed Sounder (HIRS). In this hypothetical context the relative forecast performance of each sensor is found to correlate with the size and vertical scale of increments caused by the assimilation of the radiances. Copyright © 2006 Royal Meteorological Society.
Mesoscale simulations of organized convection: Importance of convective equilibrium
Authors: Done J. M. , Craig G. C. , Gray S. L. , Clark P. A. , Gray M. E. B. 
Published: June 2006

AbstractThe validity of convective parametrization breaks down at the resolution of mesoscale models, and the success of parametrized versus explicit treatments of convection is likely to depend on the large‐scale environment. In this paper we examine the hypothesis that a key feature determining the sensitivity to the environment is whether the forcing of convection is sufficiently homogeneous and slowly varying that the convection can be considered to be in equilibrium. Two case studies of mesoscale convective systems over the UK, one where equilibrium conditions are expected and one where equilibrium is unlikely, are simulated using a mesoscale forecasting model. The time evolution of area‐average convective available potential energy and the time evolution and magnitude of the timescale of convective adjustment are consistent with the hypothesis of equilibrium for case 1 and non‐equilibrium for case 2.For each case, three experiments are performed with different partitionings between parametrized and explicit convection: fully parametrized convection, fully explicit convection and a simulation with significant amounts of both. In the equilibrium case, bulk properties of the convection such as area‐integrated rain rates are insensitive to the treatment of convection. However, the detailed structure of the precipitation field changes; the simulation with parametrized convection behaves well and produces a smooth field that follows the forcing region, and the simulation with explicit convection has a small number of localized intense regions of precipitation that track with the mid‐levelflow. For the non‐equilibrium case, bulk properties of the convection such as area‐integrated rain rates are sensitive to the treatment of convection. The simulation with explicit convection behaves similarly to the equilibrium case with a few localized precipitation regions. In contrast, the cumulus parametrization fails dramatically and develops intense propagating bows of precipitation that were not observed. The simulations with both parametrized and explicit convection follow the pattern seen in the other experiments, with a transition over the duration of the run from parametrized to explicit precipitation. The impact of convection on the large‐scaleflow, as measured by upper‐level wind and potential‐vorticity perturbations, is very sensitive to the partitioning of convection for both cases. © Royal Meteorological Society, 2006. Contributions by P. A. Clark and M. E. B. Gray are Crown Copyright.
Profiles of katabatic flow in summer and winter over Coats Land, Antarctica
Authors: Renfrew Ian A. , Anderson Philip S. 
Published: June 2006

AbstractObservations from a novel autonomous Doppler sodar wind profiling system are described and analysed. These include the first continuous wintertime soundings of katabatic winds over Antarctica—a continent with which they are synonymous. During 2002 and 2003 over 2600 wind profiles were taken during ‘case‐studies’ of high‐resolution sounding lasting hours to days. These case‐studies have been subjectively classified as: synoptically driven, katabatically influenced (28 days); primarily katabatically driven flows (a subset of 16 days); or other flow types. The Doppler sodar observations were augmented by automatic weather station observations at the field site and further up the slope, as well as synoptic and upper‐air observations at Halley Research Station, some 50 km distant on the Brunt Ice Shelf.In primarily katabatic flows there is a systematic change in the shape and depth of the low‐level katabatic jet with wind speed. Relatively strong katabatic flows (maximum winds of typically 8–10 m s−1) have a jet maximum between 20 and 60 m above the surface and are relatively deep (up to 200 m); while moderate katabatic flows (4–8 m s−1) typically have a jet maximum between 3 and 30 m and are shallower (∼100 m), although they can also be more diffuse in structure with a wind speed maximum at higher altitude. In all katabatic flows there is backing of wind direction with height, consistent with decreasing friction away from the surface. During summertime katabatic flows there is a clear diurnal signature at all heights, although this is less pronounced in the surface layer where there seems to be a persistent 2–4 m s−1 katabatic flow during all case‐studies. Where the diurnal forcing results in an abrupt katabatic flow deceleration, i.e. what may be a katabatic ‘jump’, there is a concurrent vertical acceleration. Wind profiles from a recent numerical weather prediction study of idealized katabatic flows at this site compare favourably with selected mean profiles; the only significant difference is that the model's wind speed is too low over the lowest ∼10 m. Copyright © 2006 Royal Meteorological Society.
Equine Peripheral Blood-Derived Progenitors in Comparison to Bone Marrow-Derived Mesenchymal Stem Cells
Authors: Koerner Jens , Nesic Dobrila , Romero Jose Diaz , Brehm Walter , Mainil-Varlet Pierre , Grogan Shawn Patrick 
Published: June 2006

AbstractFibroblast-like cells isolated from peripheral blood of human, canine, guinea pig, and rat have been demonstrated to possess the capacity to differentiate into several mesenchymal lineages. The aim of this work was to investigate the possibility of isolating pluripotent precursor cells from equine peripheral blood and compare them with equine bone marrow-derived mesenchymal stem cells. Human mesenchymal stem cells (MSCs) were used as a control for cell multipotency assessment. Venous blood (n = 33) and bone marrow (n = 5) were obtained from adult horses. Mononuclear cells were obtained by Ficoll gradient centrifugation and cultured in monolayer, and adherent fibroblast-like cells were tested for their differentiation potential. Chondrogenic differentiation was performed in serum-free medium in pellet cultures as a three-dimensional model, whereas osteogenic and adipogenic differentiation were induced in monolayer culture. Evidence for differentiation was made via biochemical, histological, and reverse transcription-polymerase chain reaction evaluations. Fibroblast-like cells were observed on day 10 in 12 out of 33 samples and were allowed to proliferate until confluence. Equine peripheral blood-derived cells had osteogenic and adipogenic differentiation capacities comparable to cells derived from bone marrow. Both cell types showed a limited capacity to produce lipid droplets compared to human MSCs. This result may be due to the assay conditions, which are established for human MSCs from bone marrow and may not be optimal for equine progenitor cells. Bone marrow-derived equine and human MSCs could be induced to develop cartilage, whereas equine peripheral blood progenitors did not show any capacity to produce cartilage at the histological level. In conclusion, equine peripheral blood-derived fibroblast-like cells can differentiate into distinct mesenchymal lineages but have less multipotency than bone marrow-derived MSCs under the conditions used in this study.
The Role of Exogenous Fibroblast Growth Factor-2 on the Reprogramming of Primordial Germ Cells into Pluripotent Stem Cells
Authors: Durcova-Hills Gabriela , Adams Ian R. , Barton Sheila C. , Surani M. Azim , McLaren Anne 
Published: June 2006

Abstract
The germ cell lineage is a specified cell population that passes through a series of differentiation steps before giving rise, eventually, to either eggs or sperm. We have investigated the manner in which primordial germ cells (PGCs) are reprogrammed in vitro to form pluripotent stem cells in response to exogenous fibroblast growth factor-2 (FGF-2). The response is dependent on time of exposure and concentration of FGF-2. PGCs isolated in culture show a motile phenotype and lose any expression of a characteristic germ cell marker, mouse vasa homolog. Subsequently, some but not all of the cells show further changes of phenotype, accompanied by changes in expression of endogenous FGF-2 and up-regulation of its receptor, fibroblast growth factor receptor-3, in the nucleus. We propose that it is from this reprogrammed component of the now heterogeneous PGC population that pluripotent stem cells arise.
An Evolutionary Credibility Model for Claim Numbers
Authors: Albrecht Peter 
Published: June 2006

This paper considers a particular credibility model for the claim numbersN1,N2, …,Nn, … of a single risk within a collective in successive periods 1, 2, …,n, … In the terminology of Jewell (1975) the model is an evolutionary credibility model, which means that the underlying risk parameter Λ is allowed to vary in successive periods (the structure function is allowed to be time dependent). Evolutionary credibility models for claimamountshave been studied by Bühlmann (1969, pp. 164–165), Gerber and Jones (1975), Jewell (1975, 1976), Taylor (1975), Sundt (1979, 1981, 1983) and Kremer (1982). Again in Jewell's terminology the considered model is on the other hand stationary, in the sense that the conditional distribution ofNigiven the underlying risk parameter does not vary withi.The computation of the credibility estimate ofNn+1involves the considerable labor of inverting ann×ncovariance matrix (nis the number of observations). The above mentioned papers have therefore typically looked for model structures for which this inversion is unnecessary and instead a recursive formula for the credibility forecast can be obtained. Typicallynth order stationarya priorisequences (e.g., ARMA (p, q)-processes) lead to annth order recursive scheme. In this paper we impose the restriction that the conditional distribution ofNiis Poisson (which by the way leads to a model identical to the so called “doubly stochastic Poisson sequences” considered in the theory of stochastic point processes). What we gain is a recursive formula for the coefficients of the credibility estimate (not for the estimate itself!) in case of anarbitraryweakly stationarya priorisequence. In addition to this central result the estimation of the structural parameters is considered in this case and some more special models are analyzed. Among them are EARMA-processes (which are positive-valued stationary sequences possessing exponentially distributed marginals and the same autocorrelation structure as ARMA-processes) asa priorisequence and models which can be considered as (discrete) generalizations of the Pólya process.
Credibility Approximations for Bayesian Prediction of Second Moments
Authors: William S. Jewell  , Schnieper Rene 
Published: June 2006

AbstractCredibility theory refers to the use of linear least-squares theory to approximate the Bayesian forecast of the mean of a future observation; families are known where the credibility formula is exact Bayesian. Second-moment forecasts are also of interest, for example, in assessing the precision of the mean estimate. For some of these same families, the second-moment forecast is exact in linear and quadratic functions of the sample mean. On the other hand, for the normal distribution with normal-gamma prior on the mean and variance, the exact forecast of the variance is a linear function of the sample variance and the squared deviation of the sample mean from the prior mean. Bühlmann has given a credibility approximation to the variance in terms of the sample mean and sample variance.In this paper, we present a unified approach to estimating both first and second moments of future observations using linear functions of the sample mean and two sample second moments; the resulting least-squares analysis requires the solution of a 3 × 3 linear system, using 11 prior moments from the collective and giving joint predictions of all moments of interest. Previously developed special cases follow immediately. For many analytic models of interest, 3-dimensional joint prediction is significantly better than independent forecasts using the “natural” statistics for each moment when the number of samples is small. However, the expected squared-errors of the forecasts become comparable as the sample size increases.
Draft of a System for Solvency Control in Non-Life Insurance
Authors: Norberg Ragnar , Sundt Bjørn 
Published: June 2006

AbstractAn outline is given of a proposed system for solvency control in non-life insurance that has recently been discussed within a Working Party appointed by the Norwegian supervisory authorities. According to this system the factual technical reserves must at any time be sufficient to meet, with high probability, all future liabilities stipulated by insurance contracts that have either expired or are currently in force. The system is applied to a provisional, simple model that has been fitted to claims data assembled from Norwegian non-life companies. The numerical examples illustrate, inter alia, how the required reserve depends on the volume of the business, the portfolio mix, and the reinsurance cover.
Comparison of Some Methods to Fit a Multiplicative Tariff Structure to Observed Risk Data
Authors: Ajne B. 
Published: June 2006

AbstractThree methods for fitting multiplicative models to observed, cross-classified risk data are compared. They are the method of Bailey–Simon, the method of marginal totals and a maximum likelihood method. The methods are applied to a number of risk data sets and compared with respect to balance and goodness-of-fit.
Chains of Reinsurance Revisited
Authors: Lemaire Jean , Quairiere Jean-Pierre 
Published: June 2006

AbstractChains of reinsurance were first modelled by Gerber, in a special case. It is shown that more general results can be obtained by applying Borch's theorem. The Pareto-optimal reinsurance indemnities are uniquely determined using the only assumption that the participating companies use exponential utility functions. A simple comparison then shows that Gerber's indemnities are not Pareto-optimal. Even if no assumption at all is introduced, the indemnities are shown to be closely linked to the risk aversions of the participants.
Improved Approximations for the Aggregate Claims Distribution in the Individual Model
Authors: Hipp Christian 
Published: June 2006

AbstractKornya-type higher order approximations are derived for the aggregate claims distribution and for stop loss premiums in the individual model with arbitrary positive claims. Absolute error bounds and error bounds based on concentration functions are given. In the Gerber portfolio containing 31 policies, second order approximations lead to an accuracy of 3 × 10−4, and third order approximations to 1.7 ×10−5.
On the Exact Computation of the Aggregate Claims Distribution in the Individual Life Model
Authors: De Pril Nelson 
Published: June 2006

AbstractA recursive expression is derived for computing exactly the distribution of aggregate claims of a portfolio of life insurance policies. The recursion generalizes a formula of White and Greville for the claim numbers distribution and improves Kornya's approximation method for the aggregate claims distribution. It can be seen as the counterpart in the individual model of Panjer's recursion formula for the collective model.
An Integrated System for Estimating the Risk Premium of Individual Car Models in Motor Insurance
Authors: Campbell Malcolm 
Published: June 2006

AbstractThe estimation of risk premium for individual car models is discussed. Cluster analysis is used to identify groups of car models with similar technical attributes. Credibility theory is used to combine estimates of risk premium from individual car model claim statistics, group claim statistics, and a technical assessment carried out by car experts. The procedure is applied to a small set of car models.
A kinetic study of vesicle fusion on silicon dioxide surfaces by ellipsometry
Authors: Stroumpoulis Dimitrios , Parra Alejandro , Tirrell Matthew 
Published: June 2006

AbstractEllipsometry and a mass transport model were used to investigate the kinetics of lipid bilayer formation on silicon dioxide surfaces from 100 nm diameter 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphocholine (DMPC) vesicles. For the range of concentrations studied, 0.025 to 0.380 mg/mL, the rate of the process was found to be concentration dependent and adsorption limited. Further experiments, particularly at concentrations > 0.380 mg/mL, presented evidence of net mass desorption as an intermediate step to supported lipid bilayer formation. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Use of multiple cause of death data in cancer mortality analyses
Authors: Richardson David B. 
Published: June 2006

AbstractBackgroundIn a cancer mortality study, the decision of whether to define a study outcome via underlying cause of death (UCD) or via multiple cause of death (MCD) information may impact relative risk (RR) estimates and associated confidence intervals.MethodsSimple equations are presented that relate RR estimates obtained in a cancer incidence study to the RR estimates obtained in mortality studies using UCD and MCD information. Data from the Surveillance, Epidemiology and End Results program were used to obtain information about the detection and confirmation rates of cancer diagnoses made via UCD. Data from US cause of death data tapes were used to obtain information on the ratio of UCD to MCD listings for cancer outcomes. Numerical examples illustrate the use of these equations.ResultsIn our examples, the RRs obtained via analyses of MCD were close to those obtained via analyses of UCD (but of greater precision), even when assuming that the confirmation rate of cancer diagnoses made via MCD listing was substantially lower than that of diagnoses made via UCD.ConclusionsThese finding are supportive of the use of MCD information in cancer mortality studies. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Smoking imputation and lung cancer in railroad workers exposed to diesel exhaust
Authors: Garshick Eric , Laden Francine , Hart Jaime E. , Smith Thomas J. , Rosner Bernard 
Published: June 2006

AbstractBackgroundAn association between diesel exhaust exposure and lung cancer mortality in a large retrospective cohort study of US railroad workers has previously been reported. However, specific information regarding cigarette smoking was unavailable.MethodsBirth cohort, age, job, and cause of death specific smoking histories from a companion case‐control study were used to impute smoking behavior for 39,388 railroad workers who died 1959–1996. Mortality analyses incorporated the effect of smoking on lung cancer risk.ResultsThe smoking adjusted relative risk of lung cancer in railroad workers exposed to diesel exhaust compared to unexposed workers was 1.22 (95% CI = 1.12–1.32), and unadjusted for smoking the relative risk was 1.35 (95% CI = 1.24–1.46).ConclusionsThese analyses illustrate the use of imputation in record‐based occupational health studies to assess potential confounding due to smoking. In this cohort, small differences in smoking behavior between diesel exposed and unexposed workers did not explain the elevated lung cancer risk. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Transitions of serum albumin in patients with glomerulosclerosis ‘in vivo’ characterization by electrophoretic titration curves
Authors: Bruschi Maurizio , Musante Luca , Candiano Giovanni , Santucci Laura , Zennaro Cristina , Carraro Michele , Del Boccio Piero , Gusmano Rosanna , Perfumo Francesco , Urbani Andrea , Ghiggeri Gian Marco 
Published: June 2006

AbstractHSA functions as a physiological transporter of solutes and small molecules that induce structural transitions ‘in vitro’. Analysis of these transitions requires prior purification of HSA that could introduce bias due to conformational changes. We utilized electrophoretic titration curves to describe a neutral to acid (N–A) transition of HSA directly in sera of seven patients with active focal segmental glomerulosclerosis (FSGS). The divergent electrophoretic profile of HSA was characterized by a shift in the range of pHs between 4.5 and 7.5 with an average variation of free electrophoretic mobility corresponding to loss of 1 positive charge in the pKa protonation range of histidyl residues and should involve domain I of HSA. ‘In‐gel’ determination by maleimide‐PEO2‐biotin of free SH 34 of domain I showed inaccessibility of the dye at this site in pathological HSA and alkylation with the same complex induced N–A transition in normal HSA. Potential binders of free imidazoles such as Ca++ and/or of SH 34 such as NO were excluded on the basis of direct titration and studies on binding stimulation. This is the first report describing a transition of HSA directly ‘in vivo', and the utilization of electrophoretic titration curves was critical to this purpose. This transition appears to be specific to FSGS and is unrelated to the nephrotic syndrome, Ca++ and NO binding. Spectroscopic analysis will elucidate the structural implication.
Field‐based and spectral indicators for soil erosion mapping in semi‐arid mediterranean environments (Coastal Cordillera of central Chile)
Authors: Mathieu Renaud , Cervelle Bernard , Rémy Dominique , Pouget Marcel 
Published: June 2006

AbstractThe Coastal Cordillera of central Chile is naturally sensitive to soil erosion due to moderate to steep slopes, intense winter rains when the vegetation cover is scarce, and deeply weathered granitic rocks. In 1965, 60 per cent of its surface was moderately to very severely eroded. Today this process is still largely active, but no data are currently available to evaluate the real extent, distribution and severity of soil degradation on a regional scale. This information is vital to support efficient soil conservation plans.A multi‐scale approach was implemented to produce regional land degradation maps based on remote sensing technologies. Fieldwork has shown that the surface colour or ‘redness’ and the density of coarse fragments are pertinent erosion indicators to describe a typical sequence of soil degradation in the context of mediterranean soil developed on granitic materials and micaschists. Field radiometric experiments concluded that both factors influence the reflectance of natural surfaces and can be modelled using radiometric indices accessible from most satellites operating in the optical domain, i.e. redness index and brightness index. Finally the radiometric indices were successfully applied to SPOT images to produce land degradation maps. Only broad classes of erosion status were discriminated and the detection of the degradation processes was only possible when most of the fertile layer had already been removed. This technology provides decision‐making information required to develop regional soil conservation plans and to prioritize actions between catchment areas, especially in vast inter‐tropical regions where spatialized data are not always readily available. Copyright © 2006 John Wiley & Sons, Ltd.