bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semi‐geostrophic solutions for flow over a ridge
Authors: Cullen M. J. P. 
Published: March 2007

AbstractAn algorithm for solving the semi‐geostrophic (SG) equations using real physical variables in terrain‐following coordinates is developed and used to demonstrate the expected rate of convergence of solutions of the complete equations of motion to SG solutions as the Rossby number is reduced. The tests are carried out with significant orography in a vertical slice geometry. Two asymptotic limits are tested. The SG limit is singular in one of the limits and smooth in the other. The results show the validity of using the SG model for diagnostic purposes in appropriate regimes. They also expose a number of boundary condition and numerical issues, showing that comparison with rigorous error estimates is a useful way of validating numerical procedures. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd
Filtering properties of wavelets for local background‐error correlations
Authors: Pannekoucke Olivier , Berre Loïk , Desroziers Gerald 
Published: March 2007

AbstractBackground‐error covariances can be estimated from an ensemble of forecast differences. The finite size of the ensemble induces a sampling noise in the calculated statistics. It is shown formally that a wavelet diagonal approach amounts to locally averaging the correlations, and its ability to spatially filter this sampling noise is thus investigated experimentally.This is first studied in a simple analytical one‐dimensional framework. The capacity of a wavelet diagonal approach to model the scale variations over the domain is illustrated. Moreover, the sampling noise appears to be better filtered than when only using a Schur filter, in particular for small ensembles.The filtering properties are then illustrated for an ensemble of Météo‐France Arpège forecasts. This is done both for the ‘time‐averaged correlations’, and for the ‘correlations of the day’. It is shown that the wavelets are able to extract some length‐scale variations that are related to the meteorological situation. Copyright © 2007 Royal Meteorological Society
Background error statistics for aerosols
Authors: Benedetti Angela , Fisher Michael 
Published: March 2007

AbstractAs part of the European initiative for Global Monitoring for Environment and Security (GMES), the Global and regional Earth‐system Monitoring using Satellite and in situ data (GEMS) project has been funded to provide forecasts and analysis of atmospheric constituents such as aerosols, and greenhouse and reactive gases. In this context, the development of an aerosol analysis system based on a four‐dimensional variational (4D‐Var) assimilation was started in March 2005 at the European Centre for Medium‐Range Weather Forecasts (ECMWF). As part of the main building blocks of the system, an error background covariance matrix for aerosol mixing ratio was built based on background statistics constructed from aerosol forecasts. These statistics were generated from the differences between the 48‐hour and 24‐hour forecasts of aerosol mixing ratios for sea salt, desert dust and continental particulate, using the NMC method. This method has been widely used by many numerical weather prediction centres to build background error statistics for state variables. This is the first time, to our knowledge, that it has been applied to a novel variable such as an aerosol mixing ratio, in the context of a global model. Aerosol assimilation systems have been successfully run with either observationally‐derived or model‐prescribed error covariance matrices with pre‐assigned correlation lengths. In this study, the aerosol vertical and horizontal structures of these error correlations as derived with the aid of a state‐of‐the‐art model are investigated and discussed in depth. Successively these error correlations are modelled through a spectral/wavelet approach and used to construct a background error covariance matrix. Application of this background matrix in the context of a single observation 4D‐Var experiment produced successful preliminary analyses of the total aerosol mixing ratio. Copyright © 2007 Royal Meteorological Society
Mie simulations as an error source in mineral aerosol radiative forcing calculations
Authors: Kahnert M. , Nousiainen T. , Räisänen P. 
Published: March 2007

AbstractThe role of aerosols remains a major uncertainty for climate and climate change. For the direct radiative forcing by mineral aerosols, the uncertainty in the refractive index m has been regarded as the most important error source, while the impact of aerosol non‐sphericity has been considered a minor issue and is neglected in climate models. Here, the errors caused by the spherical particle approximation (SPA) are evaluated by comparing radiative fluxes based on (i) Mie simulations and (ii) laboratory measurements of aerosol optical properties. Furthermore, they are contrasted with the errors related to the uncertainty in the refractive index. These two error sources are found to be of comparable magnitude, although they are strongly dependent on optical depth, surface albedo, and particle size. Thus, our results provide evidence that, contrary to common beliefs, the use of spherical model particles in radiative transfer simulations is probably among the major sources of error in quantifying the climate forcing effect of mineral aerosols. This stems from misrepresentation of the scattering phase function and the asymmetry parameter. Aerosol single‐scattering computations based on non‐spherical model particles are expected to reduce the shape‐related errors and thus significantly improve the accuracy of radiative forcing simulations. Copyright © 2007 Royal Meteorological Society
Psychometric reevaluation of the Women in Science Scale (WiSS)
Authors: Owen Steven V. , Toepperwein Mary Anne , Pruski Linda A. , Blalock Cheryl L. , Liu Yan , Marshall Carolyn E. , Lichtenstein Michael J. 
Published: March 2007

AbstractThe Women in Science Scale (WiSS) was first developed in 1984, and is still being used in contemporary studies, yet its psychometric properties have not been evaluated with current statistical methods. In this study, the WiSS was administered in its original 27‐item form to 1,439 middle and high school students. Confirmatory factor analysis based upon the original description of the WiSS was modestly supportive of the proposed three‐factor structure, but the claimed dimensions showed substantial redundancy. Therefore, we split our sample and performed exploratory factor analyses on one half. The most satisfactory solution, a two‐factor model, was then applied to the crossvalidation sample with a confirmatory factor analysis. This two‐factor structure was supported with a total of 14 items. Factor 1, Equality, contains eight items, and factor 2, Sexism, six items. Although our data are limited to adolescents, the WiSS, with improved psychometric properties, may be used descriptively to assess attitudes toward women in science and with additional stability and repeatability testing, may be used in evaluation research. The shortened WiSS should result in shorter administration time, fewer missing data, and increased acceptance among survey administrators in classroom settings. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 1461–1478, 2007
Novel oxylipins formed from docosahexaenoic acid by potato lipoxygenase—10(S)‐hydroxydocosahexaenoic acid and 10,20‐dihydroxydocosahexaenoic acid
Authors: Butovich Igor A. , Hamberg Mats , Rådmark Olof 
Published: March 2007

AbstractPotato tuber lipoxygenase (ptLOX) has been shown to catalyze the aerobic formation of at least four major oxygenated derivatives of DHA. Two of the products—7,17(S)‐ and 10,17(S)‐dihydro(pero)xy‐DHA [7,17‐ and 10,17‐diH(P)DHA]— were formed from soybean 15‐LOX‐derived 17(S)‐hydro(pero)xy‐DHA [17(S)‐H(P)DHA], whereas two novel oxylipin compounds— 10(S)‐hydro(pero)xy‐DHA and 10,20‐dihydro(pero)xy‐DHA [10(S)‐H(P)DHA and 10,20‐diH(P)DHA, respectively]—were the major direct products of DHA oxidation by ptLOX. The reactions proceeded relatively slowly but could be stimulated by catalytic amounts of SDS. Micromolar concentrations of 10(S)‐HPDHA effectively abolished the kinetic lag period of ptLOX activation. Enzymatic activity with DHA or 17(S)‐HPDHA as substrate was about 8% of that with linoleic acid—a standard natural ptLOX substrate—whereas 17(S)‐HDHA was converted at a rate of ∼1%. The enzyme was relatively unstable and quickly inactivated during the reaction with DHA on with 17(S)‐HPDHA (first‐order kinetic constant of inactivation kin=1.5±0.3 min−1), but not with 17(S)‐HDHA. Both 7,17‐ and 10,20‐diH(P)DHA were clearly products of double oxygenation catalyzed by soybean 15‐LOX and/or ptLOX. Our observation that ptLOX could convert 17‐HDHA to 10,17‐diH(P)DHA indicates that this dihydroxylated derivative of DHA also can be formed via a double lipoxygenation mechanism.
Effect of homocysteine, folates, and cobalamin on endothelial cell‐ and copper‐induced LDL oxidation
Authors: Ronco Ana María , Garrido Argelia , Llanos Miguel N. , Guerrero‐Bosagna Carlos , Tamayo Daniela , Hirsch Sandra 
Published: March 2007

AbstractOxidation of LDL contributes to endothelial dysfunction and atherosclerosis. This process could be associated with hyperhomocysteinemia, a condition that can be reduced after folic acid treatment. Because a reduction in LDL oxidation may improve endothelial function, we studied the effect of some vitamins (folic acid, 5‐methyltetrahydrofolic acid, and vitamin B‐12) on LDL oxidation, either in the presence or absence of homocysteine. For this purpose, two in vitro systems were used: an endothelial cell‐catalyzed LDL oxidation system and a cell‐free copper‐initiated LDL oxidation system. The kinetics of coppercatalyzed LDL oxidation was determined by continuous monitoring of the production of conjugated dienes in the reaction medium. TBARS production, a parameter of lipid peroxidation, was also evaluated. In both in vitro systems, only 5‐methyl‐tetrahydrofolic acid was able to decrease TBARS production in a concentration‐dependent manner, independently of the presence or absence of homocysteine. In the copper‐induced LDL oxidation system, vitamin B‐12 and 5‐methyltetrahydrofolic acid increased the lag time of conjugated diene production by 25 and 47%, respectively, suggesting that both vitamins in this system had antioxidant properties. Folic acid was unable to show antioxidant properties when included in either in vitro system. The results demonstrate that 5‐methyltetrahydrofolic acid and vitamin B‐12 are important protective agents against LDL oxidative modifications.
Size and number of lymph particles measured by a particle sizer during absorption of structured oils in rats
Authors: Porsgaard Trine , Kánský Jirí , Mason Sarah , Mu Huiling 
Published: March 2007

AbstractChylomicrons transport absorbed fat from the intestine to the circulation. During dietary fat absorption, the chylomicrons become larger in diameter, and in some studies an increase in chylomicron number has been observed as well. In the present study, we compared particle size and number in rat lymph following administration of four different oils. We administered fish oil, medium‐chain TAG (MCT), and two structured oils differing in intramolecular structure, with either medium‐chain FA in the outer positions of the TAG and long‐chain n−3 PUFA in the sn‐2 position (MLM oil) or with the reverse structure (LML oil), to lymph‐cannulated rats and collected lymph in fractions for the following 8 h. Chylomicron size was measured by a particle size analyzer immediately after collection, and from these data the number of chylomicrons present was estimated. The number of particles in lymph increased during the absorption of oils containing long‐chain PUFA (MLM, LML, and fish oil), whereas it was not affected by administration of MCT. The FA from MCT were probably absorbed via the portal vein; therefore, only a small number of particles were measured in lymph. When comparing the two structured oils, we observed a tendency toward a higher number of particles after LML administration, although the difference was not statistically significant. The highest number of particles after administration of all oils was observed in the size intervals 53–80 and 80–121 nm and probably represented small chylomicrons. Thus, the FA composition influenced the number of particles in lymph during absorption, whereas TAG structure had only a minor influence.
Anticancer activity and possible mode of action of 4‐O‐podophyllotoxinyl 12‐hydroxyl‐octadec‐Z‐9‐enoate
Authors: Ma Guoyi , Khan Shabana I. , Mustafa Jamal , Walker Larry A. , Khan Ikhlas A. 
Published: March 2007

Abstract4‐O‐Podophyllotoxinyl 12‐hydroxyl‐octadec‐Z‐9‐enoate (PHEFE) is a structurally novel FA analog of podophyllotoxin. In the present study, in vitro effects of PHEFE on a panel of 60 human tumor cell lines and its potential modes of anticancer action were investigated. FHEFE exhibited strong growth‐inhibitory action in a number of solid tumor cells in vitro. It did not inhibit tubulin polymerization as podophyllotoxin does; rather, it inhibited the catalytic activity of topoisomerase II. Flow cytometry and staining assay with 4,6‐diamidine‐2‐phenylindole dihydrochloride showed that PHEFE blocked the cell cycle at the G2/M phase and induced apoptosis in HL‐60 cells. These analyses suggest that PHEFE has promising anticancer characteristics that differ from podophyllotoxin and etoposide.
Distribution of polyunsaturated fatty acids including conjugated linoleic acids in total and subcellular fractions from healthy and cancerous parts of human kidneys
Authors: Hoffmann Kristina , Blaudszun Jörg , Brunken Claus , Höpker Wilhelm‐Wolfgang , Tauber Roland , Steinhart Hans 
Published: March 2007

AbstractDifferences in the FA composition of subcellular fractions from healthy and cancerous kidney tissues from the same patients were examined. Only minor differences in CLA content were found between the healthy and the cancerous tissue portions. Regarding the distribution pattern, CLA incorporation into nuclei and cytosol was significantly higher than incorporation into plasma membranes and mitochondria, which could be correlated to the neutral lipid content of these fractions. The subcellular distribution pattern of CLA was similar to that observed with monounsaturated FA but unlike that found with 18∶2n−6, which underlines the different physiological properties of CLA and 18∶2n−6. Because PUFA have been suggested to have an effect on cancer risk, the contents of n−3 and n−6 PUFA were determined in kidney and renal cell carcinoma (RCC). The 18∶2n−6 content and Δ5 desaturase activity were significantly lower, and the 18∶3n−6, 20∶3n−6, and 20∶5n−3 contents and Δ6 desaturase activity were significantly higher in RCC than in healthy renal tissue, indicating a changed PUFA metabolism in RCC. Previous research has suggested that CLA inhibits the elongation and desaturation of 18∶2n−6 into 20∶4n−6. In that case, one might speculate that a diet enriched in CLA would be a useful tool in preventing RCC. However, the involvement of CLA in preventing renal cancer could not be demonstrated definitively from the design of this experiment. Further understanding of the cause and/or consequence of the difference in FA metabolism may lead to a better understanding of RCC.
Microbiological contamination in stem cell cultures
Authors: Cobo Fernando , Cortés José Luis , Cabrera Carmen , Nieto Ana , Concha Ángel 
Published: March 2007

AbstractCell therapy and regenerative medicine are potentially two of the most exciting aspects of the novel therapeutic methods currently under development. However, these treatments present a number of important biosafety issues, like the possible transmission of microorganisms to the recipients. The most common potential form of contamination in these cell products is by bacteria (including Mycoplasma), yeast and fungi. In our study, 32 stem cell lines and feeder cell lines were analysed. There were 19 contaminated cell passages (12%). The main contaminants were gram positive cocci and Mycoplasma species, followed by gram negative rods and gram positive rods. The Mycoplasma contamination rate was 4%. Stem cell banks and other research centres aim to screen all processed stem cell lines for these microorganisms, and to assure that no contaminants are introduced in the banking procedures. It is a standard part of current good practice in stem cell banks to carry out routine microbiological controls of the stem cell lines and to work in a controlled environment to reduce the probability of contamination in the final product.
Peroxisome proliferator‐activated receptor α is involved in cardiomyocyte differentiation of murine embryonic stem cells in vitro
Authors: Ding Ling , Liang Xingguang , Zhu Danyan , Lou Yijia 
Published: March 2007

AbstractPeroxisome proliferator‐activated receptor α (PPARα) plays a key role in the transcriptional regulation of genes involved in cellular lipid and energy metabolism, which is abundantly expressed in tissues with high energy demand, including the mammalian heart. Although multiple roles for PPARα in adult cardiomyocytes have been proposed, little is known about the significance of PPARα in early differentiation of cardiomyocytes. To address this issue, murine embryonic stem (ES) cells were adopted in this study since they would differentiate in vitro into cardiomyocytes that faithfully recapitulated cardiomyocyte differentiation in vivo. As determined by semi‐quantitative RT‐PCR and Western‐blot, both PPARα and its coactivatior PGC‐1α were increased during cardiomyocyte differentiation. A positive correlation between PPARα and Troponin‐T expression was also observed by immunofluorescence in early differentiation. Application of PPARα antagonist GW6471 prevented cardiomyocyte differentiation as indicated by reduced expression of cardiac specific genes (α‐MHC, MLC2v) and cardiac sarcomeric proteins (α‐Actinin, Troponin‐T). However, gene expression of cardiac specific transcription factors (GATA4, Nkx2.5, and MEF2C) remained unchanged. Moreover, cardiomyocyte differentiation of EBs could be efficiently stimulated by WY14643 treatment, the specific agonist of PPARα. Taken together, these results suggested a facilitating role of PPARα in cardiomyocyte differentiation of murine ES cells in vitro.
Pro‐proliferating effect of homologous somatic cells on chicken primordial germ cells
Authors: Tang Xinyan , Zhang Caiqiao , Jin Yanmei , Ge Chutian , Wu Yanqun 
Published: March 2007

AbstractMany studies demonstrated that chicken primordial germ cells (PGCs) could maintain undifferentiated state on mouse embryonic fibroblast feeders supplemented with growth factors and cytokines. However, the xenosupport systems may run risk of cross‐transfer of animal pathogens from the other animal feeder, matrix to the PGCs, then influencing later transgenic technology. In this study, chicken PGCs were identified by alkaline phosphatase, stage‐specific embryonic antigen‐1 and Oct‐4 immunocytochemical stainings. Three different homologous somatic cell feeder layers (chicken embryonic fibroblast feeder layer, CEF; embryonic skeletal myoblast feeder layer; follicular granulosa cell feeder layer) were used to support growth and proliferation of PGCs to find a better supporting culture system. In addition, the effects of fetal calf serum (FCS), leukemia inhibitory factor (LIF) and the combination of insulin, transferring and selenite (ITS) on PGC proliferation were compared. Results showed that CEF was the best supporter for PGC growth and proliferation, which was verified by 5‐bromo‐2′‐deoxyuridine incorporation stain. FCS alone or in combination with LIF could significantly promote PGC proliferation in the presence of CEF in ITS medium. This study will contribute to providing a safer supporting system for chicken PGC amplification in vitro, and may be applied in transgenic chicken production and transplantation therapy.
The low rate of HLA class I molecules on the human embryonic stem cell line HS293 is associated with the APM components' expression level
Authors: Cabrera C.M. , Nieto A. , Cortes J.L. , Montes R.M. , Catalina P. , Cobo F. , Barroso‐del‐Jesus A. , Concha A. 
Published: March 2007

AbstractHuman embryonic stem cells (hESCs) represent a promise for future strategies of tissue replacement. However, there are different issues that should be resolved before these cells can be used in cellular therapies; among others, the rejection of transplantable hESCs as a result of HLA incompatibility between donor cells and recipients. The hESCs exhibit a weak HLA class I expression on the cell surface, but today the responsible mechanisms are unknown. We have analyzed the level expression of HLA class I heavy chain, beta2‐microglobulin (β2‐m), and antigen‐processing machinery (APM) components (TAP1, TAP2, LMP2, LMP7, and Tapasin) using the HS293 hESC line by real‐time quantitative RT‐PCR. This analysis has revealed a low expression of β2‐m, HLA‐B, and Tapasin, and an absence of expression of: TAP1, TAP2, LMP2, and LMP7 genes in the HS293 hESC line respect to the embryoid bodies (EBs) and the induced stem cells with IFNγ (with significant differences, p < 0.05). The lack or loss of HLA class I molecules due to the down‐regulation of the APM components has been frequently found in tumors of different histology as specific mechanisms of immune‐evasion. We described for the first time in this report that the hESCs shared similar mechanisms with respect to tumor cells responsible for the weak HLA class I expression on the cell surface.
Understanding behavioral sources of process variation following enterprise system deployment
Authors: Bendoly Elliot , Cotteleer Mark J. 
Published: March 2007

AbstractThis paper extends the current understanding of the time‐sensitivity of intent and usage following large‐scale IT implementation. Our study focuses on perceived system misfit with organizational processes in tandem with the availability of system circumvention opportunities. Case study comparisons and controlled experiments are used to support the theoretical unpacking of organizational and technical contingencies and their relationship to shifts in user intentions and variation in work‐processing tactics over time. Findings suggest that managers and users may retain strong intentions to circumvent systems in the presence of perceived task‐technology misfit. The perceived ease with which this circumvention is attainable factors significantly into the timeframe within which it is attempted, and subsequently impacts the onset of deviation from prescribed practice and anticipated dynamics.
Regulation of B-lymphocyte activation by the PH domain adaptor protein Bam32/DAPP1
Authors: Marshall A.J. , Zhang T. , Al-Alwan M. 
Published: March 2007

PI3Ks (phosphoinositide 3-kinases) play critical roles in BCR (B-cell receptor) signalling via the generation of 3-phosphoinositide second messengers. Recruitment of PH domain (pleckstrin homology domain)-containing signal transduction proteins to the plasma membrane through binding to 3-phosphoinositide second messengers represents a major effector mechanism for PI3Ks. Here, we review data on the PH domain-containing adaptor protein Bam32 (B-cell adaptor molecule of 32 kDa)/DAPP1 (dual adaptor for phosphotyrosine and 3-phosphoinositides 1), focusing on its functions in B-lymphocyte activation. Present results support the view that Bam32/DAPP1 mediates multiple PI3K-dependent responses in B-cells through membrane-proximal mechanisms involving Src kinases, Rac1, F-actin and mitogen-activated protein kinases, resulting in selective effects on BCR-mediated proliferation, antigen presentation and generation of antibody responses.