bluuebunny/crossref_metadata_2025_split huggingface dataset:
A linear‐stability analysis of the semi‐implicit semi‐Lagrangian discretization of the fully‐compressible equations
Authors: Payne T. J. 
Published: May 2008

AbstractWe give a linear‐stability analysis of the two‐time‐level semi‐implicit discretization of the adiabatic fully‐compressible equations on anf‐plane. Previous work has shown that the scheme is stable with respect to perturbations to a hydrostatic and isothermal basic state if the same time‐implicit weight is used throughout and is greater than ½. In this note, we generalize this result to the case where different time weights are used for different terms. © Crown Copyright 2008. Reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Published by John Wiley & Sons, Ltd.
Limited‐memory preconditioners, with application to incremental four‐dimensional variational data assimilation
Authors: Tshimanga J. , Gratton S. , Weaver A. T. , Sartenaer A. 
Published: May 2008

AbstractIncremental four‐dimensional variational assimilation (4D‐Var) is an algorithm that approximately solves a nonlinear minimization problem by solving a sequence of linearized (quadratic) minimization problems of the form

where x is the control vector, A is a symmetric positive‐definite matrix, b is a vector containing data and prior information, and c is a constant. This paper proposes a family of limited‐memory preconditioners (LMPs) for accelerating the convergence of conjugate‐gradient (CG) methods used to solve quadratic minimization problems such as those encountered in incremental 4D‐Var. The family is constructed from a set of vectors {si : i = 1, …, l}, where each si is assumed to be conjugate with respect to the (Hessian) matrix A. In incremental 4D‐Var, approximate LMPs from this family can be built using conjugate vectors generated during the CG minimization on previous outer iterations. The spectral and quasi‐Newton LMPs employed in many operational 4D‐Var systems are shown to be special cases of the family of LMPs proposed here. In addition, a new LMP based on Ritz vectors (approximate eigenvectors) is derived. The Ritz LMP can be interpreted as a stabilized version of the spectral LMP. Numerical experiments performed with a realistic global ocean 4D‐Var system are presented, to test the impact of the three different preconditioners. The Ritz LMP is shown to be more effective than, or at least as effective as, the spectral and quasi‐Newton LMPs in our 4D‐Var experiments. Our experiments also demonstrate the importance of limiting the number of CG (inner) iterations on certain outer iterations to avoid possible divergence of the cost function on the outer loop. The optimal number of CG iterations will depend on the specific preconditioner used, and can be computed a priori, albeit at the expense of several evaluations of the cost function on the outer loop. In a cycled 4D‐Var system, it may be necessary to perform this computation periodically to account for changes in the Hessian matrix arising from changes in the observing system and background‐flow field. Copyright © 2008 Royal Meteorological Society
Large‐eddy simulations of the diurnal cycle of shallow convection and cloudiness over the tropical Indian Ocean
Authors: Wang Hailong , McFarquhar Greg M. 
Published: May 2008

AbstractA 3‐D non‐hydrostatic model (EULAG) with warm‐rain bulk microphysics was used to study the diurnal cycle of shallow convection and cloudiness in the trade wind boundary layer over the Indian Ocean. Simulations were initialized with soundings obtained during the Indian Ocean Experiment (INDOEX). In the absence of diurnally varying large‐scale forcing, the simulated diurnal cycles of vertical velocities, turbulent fluxes, condensation rate and cloudiness were characterized by distinct daytime reductions. Solar heating in the boundary layer stabilized the air, decreased the relative humidity and, therefore, suppressed cloud‐layer turbulence and shallow cumulus convection. As a result, the condensation rate and cloud amount were reduced. Stronger thermal updraughts and turbulent fluxes caused by solar heating in the mixed layer triggered the recovery of cloudiness in the afternoon when the instability in the cloud layer increased.Sensitivity experiments showed that the principal cause of the daytime heating of the atmosphere and reductions in convection and cloudiness was not the diurnally varying surface fluxes nor the cloud radiative effects, but rather the gaseous absorption of solar radiation due mainly to water vapour in the spectral band of 2500–14 500 cm−1 and ozone in the ultraviolet and visible bands. Compared to the average short‐wave heating of 0.1 K day−1 due to cloud droplets, gases enhanced solar heating by about 2.0 K day−1 in the cloud layer. However, depending on its direction and magnitude, large‐scale vertical motion can highly modulate the diurnal cycles driven by solar heating, representing a big uncertainty in observing the diurnal cycle of shallow cumuli. Copyright © 2008 Royal Meteorological Society
The impact of mountain wakes on the drag exerted on downstream mountains
Authors: Wells H. , Vosper S. B. , Webster S. , Ross A. N. , Brown A. R. 
Published: May 2008

AbstractThe pressure drag exerted on two identical high idealised mountain ridges aligned perpendicular to the mean flow, with the second mountain lying directly downstream of the first, is investigated using a numerical model. The drag is measured for a variety of different distances between the two peaks, mountain heights and lengths and incident flows. Each two‐mountain simulation has a companion single mountain simulation, with an identical mountain and identical upstream flow, with which to compare the drag. The maximum modelled drag in the two‐mountain simulations is close to two times the drag in the single mountain case, while the minimum two‐mountain drag is similar to that exerted on the single mountain. This change in drag is a result of the wake behind the first mountain reducing the speed of the flow impacting on the second mountain. A parametrization of this effect is suggested which combines the distance between the two mountain peaks, a measure of the velocity deficit in the wake of the first mountain and the wake decay‐scale, a measure of the length‐scale over which the flow perturbation generated by the first mountain decays downwind. Copyright © 2008 Royal Meteorological Society and Crown Copyright 2008, published by John Wiley & Sons, Ltd.
A note on propagating rainfall episodes over the Bay of Bengal
Authors: Liu Changhai , Moncrieff Mitchell W. , Tuttle John D. 
Published: May 2008

AbstractAn observational analysis of precipitation episodes over the Bay of Bengal and the adjacent coastal region is conducted using the TRMM Real‐Time Multi‐Satellite Precipitation Analysis (MPA‐RT) products for three warm seasons (i.e. May to September for 2002–2004). Time–distance diagrams (Hovmüller diagrams) of rainfall episodes reveal frequent travelling precipitation episodes having lifetimes greatly exceeding those of individual convective systems. The majority of the episodes translate southward and many do not appear to have a steering level (i.e. they propagate in a hydraulic‐like manner), unlike those previously documented over midlatitude and tropical continents which usually have a steering level. On average, the coherent systems have a latitudinal span of 5 degrees and a 1‐day duration and a meridional propagation speed of 8 m s−1, approximately. The episodes mostly initiate over the coastal land around midday and offshore around midnight. Copyright © 2008 Royal Meteorological Society
Wind direction effects on orographic drag
Authors: Wells H. , Vosper S. B. , Ross A. N. , Brown A. R. , Webster S. 
Published: May 2008

AbstractA series of idealised numerical simulations is performed to investigate the effect of wind direction on the pressure forces exerted on a high elliptical mesoscale ridge in the presence of Coriolis effects. At the Rossby number considered here (Ro ∼ 13), rotational effects have a significant impact on the flow fields, however the primary effect of rotation on the drag is to provide the asymmetry required to initiate vortex shedding when the flow is perpendicular to the mountain ridge. It is found that linear theory, although not valid for such high mountains, provides a useful scaling for the variation of drag with wind direction. For a large range of wind directions, the flow is in a high‐ (super‐linear) drag state and wave breaking, vortex shedding and upstream flow blocking are observed. However, when the flow is close to being parallel to the major axis of the mountain ridge, the drag becomes sub‐linear, and none of the above processes are seen. We show that the change from a high‐drag state to a low‐drag state can be explained in terms of the aspect ratio of the mountain, that is the ratio of the across‐flow mountain length to the along‐flow length. Finally we demonstrate that the results found for the idealised elliptical mountains also apply to a real mountain of similar dimensions. Copyright © 2008 Royal Meteorological Society and Crown Copyright 2008, published by John Wiley & Sons, Ltd.
A comparison of the static SIMS and G‐SIMS spectra of biodegradable homo‐polyesters
Authors: Ogaki R. , Green F. M. , Li S. , Vert M. , Alexander M. R. , Gilmore I. S. , Davies M. C. 
Published: May 2008

AbstractStatic SIMS (SSIMS) is a surface analytical technique capable of providing molecular chemical information from solids. A major barrier to the wider take‐up of the technique is the complexity associated with the interpretation of SSIMS spectra. Quality of the interpretation depends on the expertise of analysts and making references to the limited mass spectral libraries. For many materials, there are no SSIMS library spectra. A new library‐independent method, G‐SIMS, is capable of facilitating the interpretation of SSIMS data. G‐SIMS spectra contain parent fragments, which are formed without substantial degradation or rearrangements, and highlight molecular fragments, which are directly related to the surface. In our study, G‐SIMS has been tested on medically relevant biodegradable polyester series, including poly (glycolic acid) (PGA), poly‐l‐(lactic acid) (PLA), poly‐β‐(hydroxybutyrate) (PHB) and poly‐ε‐(caprolactone) (PCL). The polyester series chosen here have closely related structures, which allow us to explore the capabilities of G‐SIMS. The G‐SIMS spectra have facilitated the identification of different polyesters by exhibiting mainly characteristic ions, representative of the polymers' molecular structures. The results also indicated that for the chosen polyester series, the larger the repeating monomer structures, the smaller the maximum number of repeat units were seen in the G‐SIMS spectra. The G‐SIMS spectra for the homologous polyester series have provided an insight into the fragmentation mechanisms as a function of repeating monomer molecular weights and structures. Copyright © 2008 John Wiley & Sons, Ltd.
Keeping properties of edible oils. III. identity of trace materials adsorbed from peanut oil by chromatography on alumina
Authors: Crossley A. , Thomas A. 
Published: May 2008

AbstractA peanut oil of improved quality was obtained by replacing active earth bleaching in the refining process by treatment with alumina. To determine which components of the oil were removed and modified by this treatment, the material adsorbed on the alumina was examined. Off‐flavor precursors were not concentrated, but chemical modification of precursors had taken place. Alumina treatment probably owes its effectiveness in part to removal of off‐flavor precursors and pro‐oxidants, and in part to suppression of undesirable side reactions which occur in bleaching earths. Hydroperoxides originally present in the oil were almost entirely destroyed on the alumina, and the adsorbate was found to be enriched in oxidized, hydroxylated, and unsaponifiable material. The presence of glycer‐ides containing both saturated and ॅ,ॆ unsat‐urated (and possibly traces of a,ॆ, े, ै diunsat‐urated) aldehyde groups was demonstrated. The adsorbate also contained a considerable proportion of glycerides containing polar groups, e.g. hydroxyl, in the fatty acid radicals; the bulk of these appeared to be hydroxydienoic acid. Gas liquid chromatography (GLC) of the methyl esters of the fatty acids of the adsorbate was used to detect simple oxidized fatty acids such as keto, epoxy, and hydroxy acids. Adsorption on alumina may prove to be a powerful tool for the isolation of aldehydoglycerides and glycerides of hydroxy‐acids from oils and fats.
The reaction of phosphorus trichloride with fatty acids
Authors: Galbraith A. R. , Hale P. , Robertson J. E. 
Published: May 2008

AbstractAn investigation of the reaction of phosphorus trichloride with fatty acids has provided a reliable guide to choice of reaction conditions. Excesses of 25舑100% phosphorus trichloride are required for high conversions; the shorter the chain length of the acid, the larger the excess of reagent required. We consider the reaction path to be satisfactorily established and have shown several hypotheses made to account for the formation of hydrogen chloride as a by‐product, to be unnecessary. Two alternative mechanisms for the reaction are proposed and discussed.
Soybean unsaponifiables: Chromatographic investigation of shell drain condensate from a commercial deodorizer
Authors: Hoffman R. L. , Evans C. D. , Cowan J. C. 
Published: May 2008

AbstractThe shell drain condensate from a commercial soybean oil deodorizer was analyzed for nonpolar unsaponifiable constituents by liquid‐liquid partition chromatography. A procedure for obtaining large quantities of these nonpolar constituents for flavor studies is described, and data on extraction techniques, purification, and analyses are presented. High‐purity soy sterols can be obtained as a by‐product.
A study of the applicability of a modified thiobarbituric acid test to flavor evaluation of fats and oils
Authors: Jacobson G. A. , Kirkpatrick J. A. , Goff H. E. 
Published: May 2008

AbstractA modified thiobarbituric acid test has been devised for the determination of certain components of oxidized fat. The reaction was carried out in a single phase solvent designed to eliminate the color extraction or fat removal steps of other TBA tests. A moderate temperature of 60C, with no added acid, was used to minimize breakdown of hydroperoxides and TBA. Under certain reaction conditions, temperature, sunlight, ferric ion, and oxygen can influence results. Of the aldehydes examined, the TBA reaction products of dienals showed an absorption peak at 532 m dm only, while the TBA reaction products of the saturated aldehydes showed a peak at 452 mॖ only. The spectral behavior of TBA reaction products of monoenals was found to vary with the location of the double bond. Fat samples, aged at either 60C or 37.8C, were examined organoleptically and by the modified TBA test. The 452 mॖ peak was of value in assessing the flavor of beef fat, cottonseed oil, and used frying fat, whereas the 532 mॖ wavelength was of value in assessing the flavor of soybean oil, used frying fat, and pork fat.
Vernonia anthelmintica (L) willd. highly purified epoxy components from the seed oil
Authors: Krewson C. F. , Luddy F. E. 
Published: May 2008

AbstractThe chief component ofVernonia anthelmintica (L.) A Willd. (ironweed) seed oil, trivernolin, and its minor components, 1,3‐divernolin and vernolic (epoxyoleic) acid, have been produced in pound quantities of commercial grade quality (93‐99% pure). Refinement of these epoxy components to chromatographically pure compounds has now been accomplished. Trivernolin has been the most difficult, vernolic acid the easiest, to purify. To upgrade trivernolin to about 100% purity, a combination of procedures was necessary including extraction, low temperature crystallizations, adsorbent treatments, and column chromatog‐raphy, each monitored by thin‐layer chromatog‐raphy (TLC). Vernolic acid of 93.7% purity was highly refined by a single pass through a silicic acid column. Some physical characteristics of these epoxy compounds are given. None of the compounds were completely stable in storage as evaluated by Chromatographic procedures.
Essential fatty acid contents of various fats: Interpretations of values by physico‐chemical tests
Authors: Alfin‐Slater Roslyn B. , Melnick Daniel 
Published: May 2008

AbstractBiological assays of oil and fat products, free from isomers of the naturally‐occurringcis‐9,cis‐12 linoleic acid, have been shown to provide estimates of essential fatty acid content which agree well with values obtained by spectrophoto‐metric analysis. However, when partially hydrogenated fats, such as those used in margarines, are bio‐assayed the estimates obtained are only about 60% of those derived by spectro‐photometric tests. In a blended corn oil margarine, good agreement was obtained for linoleic acid content by using biological assay or spectrophotometry, thio‐cyanometric procedure, column chromatography for saturates plus iodine value, and gas liquid partition (GLP) chromatography. This margarine fat contained about 29% of the essential form of linoleic acid, and had a ratio to saturated fatty acids of 1.6:1. The hydrogenated corn oil margarine is unlike conventional margarines in providing high amounts of the isomeric forms of linoleic acid which lack essential fatty acid activity. For this reason, poor agreement was obtained between biological assay results and those by physico‐chemical measurements of linoleic acid content. Such fat contains only about 6% of the essential form of linoleic acid, with a ratio to saturated fatty acids of ca. 0.3.1. From this study it is now possible to characterize, even without bio‐assay data, the fatty acid composition of a highly isomerized fat, such as is found in hydrogenated corn oil margarine. The characterization groups the fatty acids into saturates and total linoleic acids, with the latter including estimates of the positional isomers of linoleic acid with widely spaced double bonds,trans forms of linoleic acid with methylene‐in‐terrupted double bonds, linoleic acids with the double bonds in conjugated position, andcis‐9,cis‐12 linoleic acid. The combined use of the spectrophotometric and thiocyanometric procedures makes it possible to estimate the essential fatty acid content of hydrogenated fats containing residual dienes.
Menzation of mono ethenoid acids during hydrogenation
Authors: Subbaram M. R. , Youngs C. G. 
Published: May 2008

AbstractMethyl petroselinate, methyl oleate, and methyl erucate were hydrogenated under conditions used in industry for selective hydrogenation. The resulting products were separated into saturated esters andtrans‐ and cis‐unsaturated esters on a silver nitrate impregnated silicic acid column. The positional isomers in the total hydrogenated samples and the cis andtrans‐fractions were determined by oxidation with permanganate‐per‐iodate and GLC analysis of the resulting di‐carboxylic fragments. Positional isomers were found in bothtrans andcis‐fractions with equal shifting of the bond toward and away from the carboxyl group, regardless of whether the bond was originally in the 6,9, or 13 position. The ratio oftrans tocis‐form in the positional isomers in all cases was higher than the reported equilibrium proportions of 2:1.
Health Behaviors and Psychological Distress in Women Initiating BRCA1/2 Genetic Testing: Comparison with Control Population
Authors: Dorval Michel , Bouchard Karine , Maunsell Elizabeth , Plante Marie , Chiquette Jocelyne , Camden Stéphanie , Dugas Michel J. , Simard Jacques ,   INHERIT BRCAs
Published: May 2008

AbstractThe study objective was to compare breast cancer screening practices, lifestyle behaviors and psychological distress among 640 women initiating BRCA1/2 testing to those among 9,498 similarly‐aged women from the general population. Health behaviors and psychological distress were reported in a self‐administered questionnaire at pre‐test genetic counseling. Regression analyses indicate that high‐risk women were more frequently performing breast cancer screening and, in the case of those previously diagnosed with cancer, were more likely to be non‐smokers and physically active than women from general population. However, women initiating BRCA1/2 testing were significantly more distressed than controls. Globally, high‐risk women seemed to be well informed about recommendations for women who are at high risk and to have access to screening adapted to their risk level. Given their significant psychological distress, providing minimal psychosocial support to all women undergoing BRCA1/2 testing at pre‐test genetic counseling is relevant.
A Qualitative Description of Receiving a Diagnosis of Clefting in the Prenatal or Postnatal Period
Authors: Nusbaum Rachel , Grubs Robin E. , Losee Joseph E. , Weidman Carla , Ford Matthew D. , Marazita Mary L. 
Published: May 2008

AbstractThis study investigated the experience of receiving a diagnosis of clefting in the prenatal or postnatal period. Open‐ended interviews were conducted with 20 parents of children with cleft lip with or without cleft palate. Interviews were transcribed and analyzed using a qualitative descriptive approach with an emphasis on thematic analysis. Common themes emerged from participants’ responses regarding the delivery of the diagnosis, preparation for the birth of their child, advantages and disadvantages of prenatal diagnosis, use of the Internet, views on abortion and genetic testing, among other issues. All participants in the prenatal group indicated they were satisfied they learned of the cleft before the birth of their child. Some participants in the postnatal group would rather have received the diagnosis prenatally, while others were content with learning of the diagnosis in the delivery room. Greater awareness of the parental experience of the timing of receiving a cleft diagnosis may assist health care professionals in providing care for these families.
Testicular Cancer and Genetics Knowledge Among Familial Testicular Cancer Family Members
Authors: Peters June A. , Beckjord Ellen B. , Banda Ryan Deliya R. , Carr Ann G. , Vadaparampil Susan T. , Loud Jennifer T. , Korde Larissa , Greene Mark H. 
Published: May 2008

AbstractPurposeIt was our aim to determine baseline levels of testicular cancer and genetics knowledge among members of families with Familial Testicular Cancer (FTC).MethodsThis is a sub‐study of an ongoing National Cancer Institute (NCI) multidisciplinary, etiologically‐focused, cross‐sectional study of FTC. We evaluated 258 male and female participants including testicular cancer (TC) survivors, blood relatives and spouses to assess factors associated with a Genetic Knowledge Scale (GKS) and Testicular Cancer Knowledge Scale (TCKS).ResultsKnowledge levels were generally low, with genetic knowledge lower than TC knowledge (p < 0.01). Men with a personal TC history scored highest on TC knowledge, while gender, age and education differentially influenced knowledge levels, particularly among unaffected relatives.ConclusionsPrior to identifying FTC susceptibility genes, we recommend tailoring FTC genetic education to the different informational needs of TC survivors, their spouses and relatives, in preparation for the day when clinical susceptibility testing may be available.