bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative analysis of short chain fatty acids using gas liquid chromatography
Authors: Craig B. M. , Tulloch A. P. , Murty N. L.
Published: August 2007

The short‐chain fatty acids, propionic to pelargonic, have been analyzed by gas liquid chromatography, as their butyl, phenacyl, and decyl esters to overcome losses due to their volatility. The three methods are compared and the decyl ester procedure offers the most advantages.
Foaming properties of nonionic detergents
Authors: Schick M. J. , Beyer E. A.
Published: August 2007

The foam formation and foam stability of aqueous solutions of polyoxyethylene tridecanols, t‐octylphenols, nonylphenols, n‐dodecanols, and n‐octadecanols have been determined as a function of ethylene oxide chain length. In general nonionic detergents form unstable foams; the most stable foams formed by nonionic detergents are comparable to that of sodium dodecylbenzene sulfonate in the absence of foam promoters. In each homologous series of a nonionic detergent the foam formation and foam stability pass through a max at a critical hydrophilic‐hydrophobic balance (CHHB). It is shown that the CHHB corresponds to conditions of minimum foam drainage and max resistance to film rupture.
Reaction of cyclopropenoid fatty acid derivatives with hydrogen halides
Authors: Bailey A. V. , Magne F. C. , Boudreaux G. J. , Skau E. L.
Published: August 2007

The treatment ofSterculia foetida oil with concentrated aqueous HCl or with HBr in acetic acid results in the addition of one hydrohalogen molecule per cyclopropenoid moiety. Iodine value (I.V.) and infrared absorption measurements indicate that the mechanism parallels that of the polymerization of sterculic acid and involves the formation of four isomeric monoun‐saturated monohalo moieties.
Selective extraction of phospholipids from egg yolk
Authors: Ramesh B. , Adkar S. S. , Prabhudesai A. V. , Viswanathan C. V.
Published: August 2007

Solubility differences of phospholipids and tri‐glycerides in methanol have been used with advantage for the selective quantitative extraction of phospho‐lipids, almost free of triglycerides, from egg yolk. Cholesterol, a comparatively minor component of egg yolk lipids, is easily removed from the methanolic solution of phospholipids by low temperature crystal‐lization (5 C), if required.
Antimicrobial activity of aroma chemicals and essential oils
Authors: Morris J. A. , Khettry A. , Seitz E. W.
Published: August 2007

Determination of the minimum inhibitory concen‐trations (MIC) of 212 common soap fragrance raw materials demonstrated that the paper disc‐petri plate technique does not reflect the relative anti‐microbial activity of these materials. Commonly used soap bacteriostats were shown to be 100 to 1000 times more effective than the most active fragrance materials. Of 521 fragrance materials initially screened by the petri plate method, 44% were inhibitory against one of the three test organisms, and 15% were effective against all three(Staphylococcus aureus, Escherichia coli, Candida albicans). Of a selected number (212) of these positive materials, subsequently screened against a lipophilic diphtheroid organism(Corynebacterium sp.), 64 materials (30%) were positive against all four test organisms. However, only nine materials (4%) had a MIC as low as 50 ppm compared to the common soap bacteriostat TCC, which had a MIC of 0.08 ppm (vs.S. aureus). In hand‐degerming tests, no reduction of bacterial counts was obtained with a soap containing the most active fragrance materials. These results demonstrate that creation of a practical antimicrobial soap fragrance does not appear to be possible.
Analytical test methods for the inorganic portion of the detergent products
Authors: Harris J. C.
Published: August 2007

Evaluation of available methods for preliminary examination of the inorganic portion of detergent compositions indicates that this phase of the analysis has a relatively satisfactory status. Utilization of various spectrographic devices can prove most helpful in both preliminary and in final analysis of detergent components.

Several integrated schemes of analysis are available. Most of them are as yet incomplete with respect to a good analysis of sodium tripolyphosphate, but recently described techniques hold considerable promise. These general schemes are under review with the objective of using in them more effective techniques for certain components.

Individual component analyses are under critical examination, particularly those for the phosphates. A recently introduced chromatographic technique promises improvement here. Improved techniques for the determination of silica merit examination for integrated schemes as well as for single component analysis. Even sulfate analysis may be improved if published methods are indicative.

Analyses for optical brighteners, corrosion inhibitors, and carboxymethyl cellulose are needed and do not now exist in satisfactory form.
Membrane lipid peroxidation and its prevention
Authors: Mead James F.
Published: August 2007

The study of membrane peroxidation has been carried out using model systems consisting of a polyunsaturated fatty acid monolayer and an unsaturated phosphatidylcholine bilayer system. It has been shown that the major products of lipid peroxidation in monolayer and mixed saturated‐unsaturated liposomes are epoxides, hydroxy‐epoxides and their hydrolysis products. These same products are found in lungs of rats, particularly after 24 hr of breathing 6 ppm NO2. In all cases, inclusion of tocopherol introduces a lag period during which little peroxidation occurs.
Thermal oxidation of phospholipids 1,2‐dipalmitoyl‐sn‐glycerol‐3‐phosphoethanolamine
Authors: Jewell N. E. , Nawar W. W.
Published: August 2007

The purpose of this study was to compare thermal oxidation of phospholipids with that of triglycerides. Two simple saturated sys‐tems were chosen: 1, 2‐dipalmitoyl‐sn‐glycerol‐3‐phosphoethanolamine and tripalmitoylglycerol. Samples were heated at 150 C for 1 hr in air and the resulting volatile compounds analyzed qualitatively and quantitatively. Alkanes, ketones and lactones were major products in both cases. However, qualitative and quantitative differences were observed. Alkanals were absent in the oxidized phospholipid. This apparently is largely due to their reaction with the amine group as evidenced by thin layer chromatography. In addition, the phospholipid produced 2‐pentanol, 2‐methyl‐l‐pro‐panol and ethyl hexadecanoate; smaller amounts of hydrocarbons and methyl ketones than with the triacylglycerol; and no 1‐alkanols. Mechanisms which could be responsible for these observations are proposed.
A preconcentration and subsequent gas liquid chromatographic analysis method for trace volatiles
Authors: Singleton J. A. , Pattee H. E.
Published: August 2007

A glass column containing a porous polymer was used to concen‐trate headspace volatiles from enzymatically mediated reactions and inserted directly into the injection port of a gas liquid chromatog‐raphy (GLC) for elution and separation of adsorbed volatiles. The polymer column was placed in an entrainment system attached to a water aspirator at 30 psi to collect volatiles produced by the en‐zymatic reaction. A useful chromatogram was obtained from 1 g of raw material by this method. Volatiles collected in this manner could be stored on the polymer matrix at ambient temperatures without deleterious effects for subsequent GLC analysis. Multiple columns of the same or different trapping material could also be used in the entrainment system.
Development and characterization of an improved silicic acid‐KOH arrestant column for routine quantitative isolation of free fatty acids
Authors: Woo A. H. , Lindsay R. C.
Published: August 2007

An improved silicic acid‐KOH arrestant column method for the quantitative isolation of free fatty acids (FFA) is described. The method involves preparation of samples in acidified silicic acid caps that are placed directly above alkaline arrestant column portions in glass Chromatographic tubes. Neutral lipids are eluted with solvents whereas FFA are stopped as K‐salts. FFA are recovered by elution with formic acid‐containing solvents. The accuracy and reproduci‐bility of existing methods were greatly improved by minimizing and stabilizing the extent of alkali‐induced glyceride hydrolysis. The improved method is suitable for adaptation to a wide variety of food products and biological systems.
Extraction of phospholipids from plant oils and colorimetric determination of total phosphorus
Authors: Totani Yoichiro , Pretorius H. E. , Plessis L. M. du
Published: August 2007

A rapid extraction procedure to isolate phospholipids from plant oils is described. Glacial acetic acid is used as solvent and the extracted phospholipids are quantified by means of a colorimetric method.
Oxidation of unsaturated and hydroxy fatty acids by ruthenium tetroxide and ruthenium oxyanions
Authors: Nakano Y. , Foglia T. A.
Published: August 2007

The reactions of ruthenium VIII tetroxide (RuO4) and the ruthenium VII and VI oxyanions, perruthenate (RuO4−) and ruthenate (RuO4=) with hydroxy substituted and unsaturated fatty acids have been studied. At a 1:1 molar ratio, ruthenium tetroxide (RuO4) and both oxyanions (RuO4− and RuO4=) oxidized 12‐hydroxystearic acid to 12‐ketostearic acid. With 9, 10‐dihydroxystearic acid, the type of oxidation products obtained depended on the amount of ruthenium oxidant used. At high ratios of oxidant to substrate, cleavage to pelargonic and azelaic acids occurred whereas at lower ratios, partial oxidation to diketo and acyloin derivatives predominated. The oxidation of oleic acid with excess ruthenium tetroxide (RuO4) or perruthenate anion (RuO4−) gave the cleavage products pelargonic and azelaic acid through the intermediate formation of dihydroxy and diketo intermediates. Ruthenate anion (RuO4=) did not react with the double bond of oleic acid.
Accurate determination oftrans isomers in shortenings and edible oils by infrared spectrophotometry
Authors: Madison B. L. , Depalma R. A. , D’Alonzo R. P.
Published: August 2007

A procedure is described for the accurate analysis of thetrans content of fats and oils in the range of 0.5–36%trans. This procedure is shown to be more accurate than other current infrared spectrophotomeny methods. This increased accuracy is obtained by using a 2‐component calibration standard mixture and measuring the samples as methyl esters. Good agreement between this method and the measurement oftrans content by a gas chromatography procedure is demonstrated.
Ethoxyquin in fish meal
Authors: Spark A. A.
Published: August 2007

Four reliable methods are described for the determination of ethoxyquin antioxidant in fresh fish meal. These include an accurate chromatographic laboratory method, a colorimetric method, and 2 rapid factory methods, one a quantitative titration technique and the other suitable for spot checks for ethoxyquin in “go—no go” situations. With the laboratory method, 6 or 8 Chromatographie columns can be handled simultaneously. The 2 rapid methods are based on l,l‐diphenyl‐2‐picrylhydrazyl and may be used routinely in the factory to determine the antioxidant content of several hundred samples.
Titration studies of phytic acid
Authors: Evans W. J. , McCourtney E. J. , Shrager R. I.
Published: August 2007

The 12 pKa values for phytic acid have been obtained from pH titration data and nonlinear regression analysis. The pKa values ranged from 1.9 to 9.5. The results are discussed in terms of previously determined pKa values. Possible reasons are given for the differences between previously determined values and present values.
Preparation of low‐phytate rapeseed protein by ultrafiltration: I. The aqueous extraction of phytate from deoiled rapeseed meals
Authors: Siy R. D. , Talbot D. F.
Published: August 2007

The extraction of phytate and nitrogen‐ and phosphorus‐containing compounds from Tower and Candle variety rapeseed meal and flour using aq sodium chloride solution has been investigated. Single‐stage extraction experiments were made varying the v/n ratio from 10 to 500 mL of extract solution per g of sample and using an extract solution containing 0–10% (w/v) sodium chloride. The pH of the extract solution was varied from 3.0 to 10.0. It was found that phytate and phosphorus‐containing compounds can be completely extracted whereas the extent of extraction of nitrogen‐containing compounds ranged from 27 to 75% and depended on the extent of protein denaturation of the sample. The above observations were found to be independent of the pH of the extract solution. The extraction method is viewed as a first step in the membrane preparation of a low‐phytate rapeseed protein.
Epoxidation of methyl 4‐hydroxy‐trans‐2‐hexadecenoate
Authors: Ahmad M. S. , Rauf A. , Osman S. M.
Published: August 2007

Reaction of methyl 4‐hydroxy‐trans‐2‐hexadecenoate (1b) withm‐chloroperbenzoic acid (1.0 mol) in chloroform yielded methyl 4‐hydroxy‐trans‐2,3‐epoxyhexadecanoate (2) in 32% yield. Reaction with 2 mol afforded both methyl 4‐oxo‐trans‐2‐hexadecenoate (3) (15.3%) and (2) (65.8%). The presence of an allylic hydroxyl group in the α,β‐unsaturated ester enhances the yield of the epoxidation product (2) as well as the keto compound (3). The structures of individual reaction products were established by elemental analyses as well as by spectral studies.
Determination of trace elements in oils by plasma emission spectroscopy
Authors: Dijkstra A. J. , Meert D. , Safinco N. V.
Published: August 2007

An analytical method for the determination of phosphorus and other elements at low concentrations in edible oils has been developed using a plasma emission spectrometer. The method is fast because it eliminates the ashing process in sample preparation and because the actual measurement takes less than 1 min. Reproducibility and accuracy of the measurement are good and very low detection limits have been observed, e.g., 0.5 ppm for phosphorus and 5 ppb for copper. However, the long‐term stability of the instrument cannot as yet be guaranteed and a procedure that prescribes regular measurement of samples of known concentration is essential as a means of detecting any drift in the output signal.
A spray‐dried α‐olefin sulfonate from concept to marketplace
Authors: Cullotta C. P. , Shultz A.
Published: August 2007

This paper examines the spray drying process, particularly the spray drying of α‐olefin sulfonates. Topics covered center on the spray drying process for α‐olefin sulfonates, important parameters and considerations in that spray drying process, and an examination of the product from the spray tower. Product development from laboratory to pilot plant is described with attendant translation to full‐scale facilities. At least 4 different cocurrent spray‐drier units are illustrated and key parameters are discussed.
Critical micelle concentration of lauric acid‐diethanolamine condensate by polarographic and spectrophotometric methods: A comparative study
Authors: Malik Wahid U. , Chand Puran
Published: August 2007

The critical micelle concentration (cmc) values of surfactants obtained by different physical methods do not show any concordance especially in cases when determinations are made in presence of electrolytes. With lauric acid‐diethanolamine condensate, the behavior is altogether different.

A comparison of the spectrophotometric and polarographic determinations, with and without the presence of extraneous electrolytes reveals that the cmc values in both cases are almost similar. The results indicate that the cmc values of nonionic surfactants are not affected by acids, bases and salts when added in low concentrations.
Vernolic acid esters as plasticizers for polyvinyl chloride
Authors: Riser George R. , Riemenschneider R. W. , Witnauer Lee P.
Published: August 2007

The methyl, propyl, butyl, isobutyl, hexyl, cyclohexyl, octyl, and 2‐ethylhexyl esters of vernolic (epoxyoleic) acid, a naturally‐occurring epoxy acid, were prepared and evaluated as plasticizers of polyvinyl chloride. All the esters showed good compatibility. The data indicated that they are excellent low temperature plasticizers having Tf temperatures below 蜢50C. They also have the added advantage of greatly increasing the heat stability of the polyvinyl chloride and improving the light stability. The results are compared with DOP and other epoxy‐containing plasticizers now being used commercially. These esters should not only be useful as primary plasticizers but also in combination with other plasticizers as plasticizer‐stabilizers.
Lipid changes in maturing oil‐bearing plants
Authors: McKillican Mary E.
Published: August 2007

Seeds ofCrambe abyssinica C.D. 6619 and theBrassica napus varieties Golden and Zero‐erucic were collected at different stages of maturity and the free lipid extracted with hexane. The lipid thus obtained was separated into lipid classes by silicic acid column chromatography. The lipid classes were further examined by thin‐layer chromatography and the component fatty acids and sterols by gas‐liquid chromatography.

The relative amounts of the lipid classes in crambe and both rape varieties varied as the seed matured and a period of great change occurred about 10 days after fertilization. The greatest change was in triglycerides and phospholipids plus glycolipids. Free fatty acids, present in immature seeds, has almost disappeared at maturity. The lipid classes of crambe and both types of rape were in similar proportion at maturity. Differences in phospholipid and glycolipid composition were found between crambe and rape and between immature and mature rape. The fatty acid composition differred between lipid classes and changed with maturity. Changes in 18‐carbon acids of Zero‐erucic rape were concurrent with the development of erucic and eicosenoic acids in Golden rape.
Utility of branched chain carboxylic acids in the manufacture of driers
Authors: Fischer Alfred
Published: August 2007

To be useful in the manufacture of driers, a carboxylic acid must yield lead, cobalt, manganese, calcium and zinc soaps which are soluble in paint vehicles and petroleum hydrocarbon thinners. The drying metal soaps of a number of saturated branched chain carboxylic acids were prepared to determine the relationship of acid structure to metal soap solubility. It was found that with the exception of 4‐ethyl‐5,5‐dimethyl‐hexanoic acid those branched chain acids containing at least six carbon atoms in the longest straight chain yielded soluble drying metal soaps and were therefore useful in drier manufacture. soluble 舠basic舡 lead soaps, pale‐colored manganese soaps and reddish purple cobalt soaps were obtained from acids lacking in alpha branching. Alpha‐branched acids yielded insoluble basic lead soaps, dark manganese soaps and dark blueviolet cobalt soaps.
Industrial hydrogenation of cottonseed oil: A compositional study
Authors: Sreenivasan B. , Holla K. S. , Ichaporia M. B.
Published: August 2007

Intermediate samples during a typical plant hydrogenation of cottonseed oil for vanaspati (shortening) manufacture have been examined for their fatty acid composition by gas‐liquid chromatography andtrans isomers content by infrared spectrophotometry. In the initial stages, hydrogenation of linoleate proceeds almost exclusively in preference to that of oleate. During this period,trans isomers are also formed at a rapid rate. It has been proposed that this high selectivity and hightrans isomer formation are linked to the formation of conjugated diene from linoleate as a first step in the hydrogenation. It has been found that a linear relationship exists between the linoleate content and thetrans isomers content or thek10.38 ॖ values of the glycerides. The practical utility of this plot is that it can be employed as a guide to arrest the process at any desired linoleate level.
trans Fatty Acid Content of Canadian Margarines Prior to Mandatory trans Fat Labelling
Authors: Ratnayake W. M. N. , Gagnon C. , Dumais L. , Lillycrop W. , Wong L. , Meleta M. , Calway P.
Published: August 2007

Dietary trans fatty acids (TFA) are of major concern because of their adverse effects on blood lipid levels and coronary heart disease. In Canada, margarines were significant sources of TFA during the 1980s and 1990s. However, this is expected to change with increased public awareness over their adverse health effects and the introduction of new legislature to include TFA content on the Nutritional Facts table of food labels. In this study, the TFA content of the top‐selling 29 Canadian margarines, which represented 96.3% of the market share, was determined by capillary gas‐liquid chromatography in order to assess the influence of regulatory development during the 3‐year transition period between the announcement of new food labelling regulations in Canada that require mandatory declaration of the trans fat content in most pre‐packaged foods in January 2003 and its enforcement on 12 December 2005. The 29 margarines included 15 tub margarines made from non‐hydrogenated vegetable oils (NHVO‐tub margarines), 11 tub margarines made from partially hydrogenated vegetable oils (PHVO‐tub margarines) and three print margarines, which were also made from partially hydrogenated vegetable oils (PHVO‐print margarines). The 15 NHVO tub‐margarines accounted for 71% of the total margarine market share and generally contained less than 2% TFA (mean value 0.9 ± 0.3% of total fatty acids). The mean total TFA contents of PHVO‐tub margarines and PHVO‐print margarines, were 20.0 ± 4.5% and 39.6 ± 3.5%, and their market shares were 19.3 and 6.0%, respectively. Although during the last 10 years, increasing number of soft tub margarines that contained very little trans fats have been made available in Canada, the PHVO‐tub‐ and ‐print margarines still contain high levels of trans fats similar to those margarines that were sold in the 1990s. The market share data suggest that the margarines prepared using NHVO and containing almost no TFA were preferred by Canadians over those margarines prepared using PHVO, even before the mandatory declaration of TFA content came into effect on 12 December 2005.
Die Genetik der bipolaren Störung
Authors: Cichon S. , Rietschel M.
Published: August 2007

Mit einer Lebenszeitprävalenz von 0,5–1,5% ist die bipolare (manisch-depressive) Störung eine in der Bevölkerung häufige psychiatrische Krankheit. Familien-, Zwillings- und Adoptionsuntersuchungen belegen, dass genetische Faktoren an der Krankheitsentstehung beteiligt sind. Genomweite Kopplungsuntersuchungen haben chromosomale Regionen nachgewiesen, in denen sich mit großer Wahrscheinlichkeit Krankheitsdispositionsgene befinden. Meta-Analysen deuten aber darauf hin, dass die Effekte der einzelnen Loci relativ begrenzt sind, was möglicherweise die Schwierigkeiten bei dem nachfolgenden Schritt der Genidentifizierung erklärt. In jüngster Zeit versprechen genomweite Assoziationsuntersuchungen unter Verwendung hunderttausender „single nucleotide polymorphisms“ (SNPs) in großen, phänotypisch gut charakterisierten Kohorten von Patienten und Kontrollen entscheidende Durchbrüche bei der Suche nach den beteiligten Genen.
The Arterial Switch Procedure for Transposition of the Great Arteries
Authors: DeBord Starla , Cherry Cecile , Hickey Carol
Published: August 2007

TRANSPOSITION OF THE GREAT ARTERIES is the most common congenital heart defect among the birth defects that present with cyanosis during the early neonatal period.

INFANTS WITH THIS CARDIAC BIRTH DEFECT, in which the aorta originates from the right ventricle and the pulmonary artery originates from the left ventricle, usually do not survive without surgical intervention in the first few days of life.

THE ARTERIAL SWITCH PROCEDURE, performed via a median sternotomy incision during cardiopulmonary bypass, restores the aorta and pulmonary artery to their normal anatomic positions. AORN J 86 (August 2007) 211‐226. © AORN, Inc, 2007.
Practice and Education: Partnering to Address the Perioperative Nursing Shortage
Authors: Trice Lucy B. , Brandvold Catherine , Bruno Elizabeth
Published: August 2007

WITH THE GROWING SHORTAGE of nurses in the workforce, perioperative leaders are facing a significant challenge in recruiting new nurses who are committed to perioperative nursing.

ONE MEDICAL CENTER in northern Florida developed a successful summer externship program to introduce nursing students to the perioperative environment. The program incorporates both didactic and clinical experiences.

STUDENTS WHO COMPLETE the program are better prepared and motivated to choose a career in perioperative nursing. The retention rate for nurses from the externship program who were hired into the OR in which the program was conducted was 89% after two years. AORN J 86 (August 2007) 259‐264. © AORN, Inc, 2007.
Reviews
Authors: Scherffius Jo Ann , Harvey Mary Kay , Collins Lethia , Radford Mary
Published: August 2007

Coaching for Emotional Intelligence: The Secret to Developing the Star Potential in Your Employees, Bob Wall, 2006, 256 pages, $24.95 hardcover

Save the First Dance for You—The Complete Nurse's Guide to Serving Your Profession, Your Patients, and Yourself, Doris Young, 2007, 215 pages, $29.95 hardcover

The New Medicine$: How Drugs Are Created, Approved, Marketed, and Sold, Bernice Schacter, 2006, 280 pages, $44.95 hardcover

The Best Medicine: Book of Cartoons, AORN, 2006, 86 pages, $15.95 members/$20.95 nonmembers softcover
Oxidative folding of nerve growth factor can be mediated by the pro‐peptide of neurotrophin‐3
Authors: Hauburger Anja , Kliemannel Marco , Madsen Peder , Rudolph Rainer , Schwarz Elisabeth
Published: August 2007

We have previously shown that the pro‐peptide of human nerve growth factor (NGF) facilitates oxidative folding of the mature part. For the analysis of functional specificities of the pro‐peptides of NGF and the related neurotrophin‐3 (NT‐3) with respect to structure formation, chimeric proteins with swapped pro‐peptides were generated. Neither the structure nor the stability of the mature domains was influenced by the heterologous pro‐peptides. For the pro‐peptide of NT‐3 fused to the mature part of NGF, stabilization of the pro‐peptide moiety by the NGF part was observed. Folding kinetics and renaturation yields of this chimeric protein were comparable to those of proNGF. Our results demonstrate functional interchangeability between the pro‐peptides of NGF and NT‐3 with respect to their role in assisting oxidative folding of the mature part.
Outsourcing of front‐end business processes: Quality, information, and customer contact
Authors: Balakrishnan Karthik , Mohan Usha , Seshadri Sridhar
Published: August 2007

We examine the recent supply chain phenomenon of outsourcing front‐end business processes in this paper. Few, if any, of the existing theories provide satisfactory explanation for the rapid growth in this area. We use a model proposed by Sridhar and Balachandran [Sridhar, S.S., Balachandran, B.V. 1997. Incomplete information, task assignment, and managerial control systems. Manage. Sci. 43(6), 764–778] to determine the factors that might contribute to this phenomenon. Our analysis reveals that the ability of the vendor to forecast the task environment without bias and to gain sophistication in interpreting contract terms might make the firm indifferent between outsourcing and retaining front‐end processes in‐house. We validate our findings against the work of Apte and Mason [Apte, U.M., Mason, R.O., 1995. Global disaggregation of information‐intensive services. Manage. Sci. 41(7), 1250–1262], who develop a theoretical framework to identify criteria for companies to select services to be outsourced. They base their decisions predominantly on the nature of “customer contact.” The combined theories are shown to provide a rich framework for identifying customer‐facing tasks that can be outsourced.
Reactive control of transition induced by free-stream turbulence: an experimental demonstration
Authors: LUNDELL FREDRIK
Published: August 2007

The present wind-tunnel experiment demonstrates that a reactive control system is able to decrease the amplitude of random disturbances in a flat-plate boundary layer. The disturbances were induced in a laminar boundary layer by a turbulent free stream. The control system consisted of upstream wall-shear-stress sensors (wall wires) and downstream actuators (suction through holes). An ad hoc threshold-and-delay control algorithm is evaluated and parameter variations were performed in order to find a suitable working point of the control system. Detailed measurements of the flow field show how the control influences the disturbances in the boundary layer, whereas the effect on the mean flow owing to the control is minute. The control system manages to inhibit the growth of the fluctuations of the streamwise velocity component for a considerable distance downstream of the two actuator positions. Further downstream, however, the amplitudes of the fluctuations grow again. The flow rate used to obtain the control effect is one sixth of that necessary if continuous distributed suction is used to reach the same control objective. Finally, correlations and spectra show that the elongation of the structures in the streamwise direction is eliminated in the regions where the control has the largest effect. The spanwise scale of the disturbances is not affected by the control.
Large-Reynolds-number asymptotic analysis of viscous centre modes in vortices
Authors: LE DIZÈS STÉPHANE , FABRE DAVID
Published: August 2007

This paper presents a large-Reynolds-number asymptotic analysis of viscous centre modes on an arbitrary axisymmetrical vortex with an axial jet. For any azimuthal wavenumber m and axial wavenumber k, the frequency of these modes is given at leading order by ω0 = mΩ0 + kW0 where Ω0 and W0 are the angular and axial velocities of the vortex at its centre. These modes possess a multi-layer structure localized in an O(Re−1/6) neighbourhood of the vortex. By a multiple-scale matching analysis, we demonstrate the existence of three different families of viscous centre modes whose frequency expands as ω(n) ∼ ω0 + Re−1/3ω1 + Re−1/2ω(n)2. One of these families is shown to have unstable eigenmodes when H0 = 2Ω0k(2kΩ0 − mW2) < 0 where W2 is the second radial derivative of the axial flow in the centre. The growth rate of these modes is given at leading order by σ ∼ (3/2)(H0/4)1/3Re−1/3. Our results prove that any vortex with a jet (or jet with swirl) such that Ω0W2 ≠ 0 is unstable if the Reynolds number is sufficiently large. The spatial structure of the viscous centre modes is obtained and simple approximations which capture the main feature of the eigenmodes are also provided.

The theoretical predictions are compared with numerical results for the q-vortex model (or Batchelor vortex) for Re ≥ 105. For all modes, a good agreement is demonstrated for both the frequency and the spatial structure.
Effects of initial conditions in decaying turbulence generated by passive grids
Authors: LAVOIE P. , DJENIDI L. , ANTONIA R. A.
Published: August 2007

The effects of initial conditions on grid turbulence are investigated for low to moderate Reynolds numbers. Four grid geometries are used to yield variations in initial conditions and a secondary contraction is introduced to improve the isotropy of the turbulence. The hot-wire measurements, believed to be the most detailed to date for this flow, indicate that initial conditions have a persistent impact on the large-scale organization of the flow over the length of the tunnel. The power-law coefficients, determined via an improved method, also depend on the initial conditions. For example, the power-law exponentmis affected by the various levels of large-scale organization and anisotropy generated by the different grids and the shape of the energy spectrum at low wavenumbers. However, the results show that these effects are primarily related to deviations between the turbulence produced in the wind tunnel and true decaying homogenous isotropic turbulence (HIT). Indeed, when isotropy is improved and the intensity of the large-scale periodicity, which is primarily associated with round-rod grids, is decreased, the importance of initial conditions on both the character of the turbulence andmis diminished. However, even in the case where the turbulence is nearly perfectly isotropic,mis not equal to −1, nor does it show an asymptotic trend inxtowards this value, as suggested by recent analysis. Furthermore, the evolution of the second- and third-order velocity structure functions satisfies equilibrium similarity only approximately.
Atomization of undulating liquid sheets
Authors: BREMOND N. , CLANET C. , VILLERMAUX E.
Published: August 2007

The fragmentation of a laminar undulating liquid sheet flowing in quiescent air is investigated. Combining various observations and measurements we propose a sequential atomization scenario describing the overall sheet–drop transition in this configuration. The undulation results from a controlled primary Kelvin–Helmholtz instability. As the liquid travels through the undulating pattern, it experiences transient accelerations perpendicular to the sheet. These accelerations trigger a secondary instability responsible for the amplification of spanwise thickness modulations of the sheet. This mechanism, called the ‘wavy corridor’, is responsible for the sheet free edge indentations from which liquid ligaments emerge and break, forming drops. The final drop size distribution is of a Gamma type characterized by a unique parameter independent of the operating conditions once drop sizes are normalized by their mean.
Evolution of solitary waves and undular bores in shallow-water flows over a gradual slope with bottom friction
Authors: EL G. A. , GRIMSHAW R. H. J. , KAMCHATNOV A. M.
Published: August 2007

This paper considers the propagation of shallow-water solitary and nonlinear periodic waves over a gradual slope with bottom friction in the framework of a variable-coefficient Korteweg–de Vries equation. We use the Whitham averaging method, using a recent development of this theory for perturbed integrable equations. This general approach enables us not only to improve known results on the adiabatic evolution of isolated solitary waves and periodic wave trains in the presence of variable topography and bottom friction, modelled by the Chezy law, but also, importantly, to study the effects of these factors on the propagation of undular bores, which are essentially unsteady in the system under consideration. In particular, it is shown that the combined action of variable topography and bottom friction generally imposes certain global restrictions on the undular bore propagation so that the evolution of the leading solitary wave can be substantially different from that of an isolated solitary wave with the same initial amplitude. This non-local effect is due to nonlinear wave interactions within the undular bore and can lead to an additional solitary wave amplitude growth, which cannot be predicted in the framework of the traditional adiabatic approach to the propagation of solitary waves in slowly varying media.
Two-dimensional flow of foam around a circular obstacle: local measurements of elasticity, plasticity and flow
Authors: DOLLET BENJAMIN , GRANER FRANÇOIS
Published: August 2007

We investigate the two-dimensional flow of a liquid foam around a circular obstacle by measuring all the local fields necessary to describe this flow: velocity, pressure, and bubble deformations and rearrangements. We show how our experimental set-up, a quasi-two-dimensional ‘liquid pool’ system, is adapted to the determination of these fields: the velocity and bubble deformations are easy to measure from two-dimensional movies, and the pressure can be measured by exploiting a specific feature of this system, a two-dimensional effective compressibility. To describe accurately neighbour swapping (so-called ‘T1’ processes), we propose a new, tensorial descriptor. All these quantities are evaluated via an averaging procedure that we justify by showing that the fluctuations of the fields are essentially Gaussian. The flow is extensively studied in a reference experimental case; the velocity presents an overshoot in the wake of the obstacle, and the pressure is maximum at the leading side and minimal at the trailing side. The study of the elastic deformations and of the velocity gradients shows that the transition between plug flow and yielded regions is smooth. Our tensorial description of T1s highlights their correlation both with the bubble deformations and the velocity gradients. A salient feature of the flow, notably for the velocity and T1 distribution, is a marked fore–aft asymmetry, the signature of the elastic behaviour of the foam. We show that the results do not change qualitatively when various control parameters (flow rate, bubble area, fluid fraction, bulk viscosity, obstacle size and boundary conditions) vary, identifying a robust quasi-static regime. These results are discussed in the framework of the foam rheology literature. A movie is available with the online version of the paper.
Scaling analysis and simulation of strongly stratified turbulent flows
Authors: BRETHOUWER G. , BILLANT P. , LINDBORG E. , CHOMAZ J.-M.
Published: August 2007

Direct numerical simulations of stably and strongly stratified turbulent flows with Reynolds number Re ≫ 1 and horizontal Froude number Fh ≪ 1 are presented. The results are interpreted on the basis of a scaling analysis of the governing equations. The analysis suggests that there are two different strongly stratified regimes according to the parameter $\mathcal{R} \,{=}\, \hbox{\it Re} F^2_h$. When $\mathcal{R} \,{\gg}\, 1$, viscous forces are unimportant and lv scales as lv ∼ U/N (U is a characteristic horizontal velocity and N is the Brunt–Väisälä frequency) so that the dynamics of the flow is inherently three-dimensional but strongly anisotropic. When $\mathcal{R} \,{\ll}\, 1$, vertical viscous shearing is important so that $l_v \,{\sim}\, l_h/\hbox{\it Re}^{1/2}$ (lh is a characteristic horizontal length scale). The parameter $\cal R$ is further shown to be related to the buoyancy Reynolds number and proportional to (lO/η)4/3, where lO is the Ozmidov length scale and η the Kolmogorov length scale. This implies that there are simultaneously two distinct ranges in strongly stratified turbulence when $\mathcal{R} \,{\gg}\, 1$: the scales larger than lO are strongly influenced by the stratification while those between lO and η are weakly affected by stratification. The direct numerical simulations with forced large-scale horizontal two-dimensional motions and uniform stratification cover a wide Re and Fh range and support the main parameter controlling strongly stratified turbulence being $\cal R$. The numerical results are in good agreement with the scaling laws for the vertical length scale. Thin horizontal layers are observed independently of the value of $\cal R$ but they tend to be smooth for $\cal R$< 1, while for $\cal R$ > 1 small-scale three-dimensional turbulent disturbances are increasingly superimposed. The dissipation of kinetic energy is mostly due to vertical shearing for $\cal R$ < 1 but tends to isotropy as $\cal R$ increases above unity. When $\mathcal{R}$ < 1, the horizontal and vertical energy spectra are very steep while, when $\cal R$ > 1, the horizontal spectra of kinetic and potential energy exhibit an approximate k−5/3h-power-law range and a clear forward energy cascade is observed.
Rough-wall boundary layers: mean flow universality
Authors: CASTRO IAN P.
Published: August 2007

Mean flow profiles, skin friction, and integral parameters for boundary layers developing naturally over a wide variety of fully aerodynamically rough surfaces are presented and discussed. The momentum thickness Reynolds numberReθextends to values in excess of 47000 and, unlike previous work, a very wide range of the ratio of roughness element height to boundary-layer depth is covered (0.03  0.5). Comparisons are made with some classical formulations based on the assumption of a universal two-parameter form for the mean velocity profile, and also with other recent measurements. It is shown that appropriately re-written versions of the former can be used to collapse all the data, irrespective of the nature of the roughness, unless the surface is very rough, meaning that the typical roughness element height exceeds some 50% of the boundary-layer momentum thickness, corresponding to about$h/\delta\,{\widetilde{>}}\,0.2$.
Polymer mixing in shear-driven turbulence
Authors: VAITHIANATHAN T. , ROBERT ASHISH , BRASSEUR JAMES G. , COLLINS LANCE R.
Published: August 2007

We investigate numerically the influence of polymer mixing on shear-driven turbulence. Of particular interest is the suppression of mixing that accompanies drag reduction with dilute polymer solutions. The simulations use the finite extensible nonlinear elastic model with the Peterlin closure (FENE-P) to describe the polymer stresses in the momentum equation, with polymer concentration allowed to vary in space and time. A thin slab of concentrated polymer was placed in an initially Newtonian homogeneous turbulent shear flow on a plane perpendicular to the mean velocity gradient, and allowed to mix in the gradient direction while actively altering the turbulence. The initially higher concentration of polymer near the centreplane suppressed production of turbulent kinetic energy and Reynolds stress in that region, while turbulence outside the polymer-rich region remained shear-dominated Newtonian turbulence. The rate of mixing in the shear direction was severely damped by the action of the polymer compared to a passive scalar in the corresponding Newtonian turbulent shear flow. This, in part, was a result of the same damping of vertical velocity fluctuations by the polymer that leads to the suppression of momentum flux. However, the cross-correlation between the polymer concentration and vertical velocity fluctuations was also suppressed, indicating that the explanation for the reduction in polymer mixing involves both the suppression of vertical velocity fluctuations and an alteration of turbulence structure by the polymer–turbulence interactions.
Reviewing the aerial view
Authors: Boldrick Stocy
Published: August 2007

A group organised by the University of Edinburgh, led by Mark Dorrian, and CNRS Paris, led by Frédéric Pousin is exploring the history and the cultural meanings of the aerial view. It aims to investigate how the aerial view can be defined, how images are produced, how ‘elevated’ one has to be in order to produce or experience an aerial view, and how images are used and consumed. Jointly funded by the British Academy and CNRS, a numberof meetings will be held over the next two years. The following account reports on the first meeting held in Edinburgh on 3 February 2007.
Karle / Buxbaum: the ordinary in procurement and design
Authors: Schmiedeknecht Torsten
Published: August 2007

Contemporary criticism in architecture frequently ignores the procurement process that a project has undergone and its impact on the design of a building. Critics tend to concentrate on the finished product, the building, paying little or no attention to how the architect secured the job, who the client was, how they were represented, the client / architect relationship and how these had an impact on both design and design process, beyond functional requirements.
Plato and Hegel stay home
Authors: Tobe Renée
Published: August 2007

As we watch a film, we let filmmakers take us by the hand and tell us a story until they lead us into a world visually constructed to captivate us for a specific amount of time. The worst thing a filmmaker can do is not to terrify us, or fool us with special effects, but to rob us of our illusion that what we are seeing is ‘true’ even if just for now. Through the mimetic power of film, we, the viewer, picture the film set as if it is real architecture, and assemble the walls and floors we see into an architectural whole. This paper focuses on what we see ‘behind’ the screen rather than the cinematic experience itself. The premise is that by examining the nature of filmic ‘reality’ we will be helped to understand architectural form and order.
Autonomy and commerce: the integration of architectural autonomy
Authors: Kaminer Tahl
Published: August 2007

More than three decades ago, the architectural historian Manfredo Tafuri pessimistically concluded that a revolutionary architecture cannot precede a social revolution. In this comment, he summed up the perceived failure of Modernist architecture to realise a social utopia. The comment implied that the architectural discipline, as part of the superstructure, cannot affect society; rather, it is the means and forces of production which determine society, while architecture only reacts, corresponds and represents these changes.
Visual discoveries of an urban wanderer: August Endell's perception of a beautiful metropolis
Authors: Eisenschmidt Alexander
Published: August 2007

An unorthodox and influential critique of the modern city was published in 1908 by August Endell, an autodidact in the field of architecture. Influenced by empathy theory, Impressionist ideas, contemporary sociology, and the literary and artistic circles of the time, Endell's small book Die Schönheit der Großen Stadt (The Beauty of the Metropolis) read the metropolis through a new way of ‘seeing’ [1,2]. What he saw was surprising for most readers: the city's centre was discovered in marginal sites, and its lasting identity was grasped in its fleeting moments. Although Endell never drew up encompassing schemes for the city, did not participate in the first city-building competitions of the time, and focused primarily on individual building projects, one of his major publications was entirely devoted to the city. The Beauty of the Metropolis takes the reader on a journey through a city that slowly reveals itself as Berlin. Throughout the book, Endell describes urban scenes such as streets, plazas, stations, and the margins of urbanity, such as the city's blank walls and outskirts.
Skyscrapers as an instrument for economic development: the case of Amman
Authors: Abu-Ghozalah Samer
Published: August 2007

Concern with economic performance dominates the urban agenda of most modern cities, but this objective is pursued differently according to the ideology of the community. Amman follows distinctive development trajectories that reflect both the interactions of global forces and the local community. The primary global force affecting Amman is the competitive international environment engendered by economic globalisation that makes the city an increasingly attractive location for investment. This competition is manifested in city marketing strategies that reflect the desire to attract multinational corporations and specialists. The political ideology of the city plays an important role in the globalisation process currently taking place in Amman. In the USA, city planning is undertaken by different developmental agencies with limited participation of the city-region scale, while in Western Europe the state is involved in urban development and planning. Amman's situation is a mixture between state control and economic liberalism in which urban development is determined by the planning vision of attracting foreign investment and reduced restrictions to free enterprise.