bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase behavior of a binary lipid shortening system: From molecules to rheology
Authors: Humphrey K. L. , Moquin P. H. L. , Narine S. S.
Published: November 2006

The phase behavior of fully hydrogenated canola oil in soybean oil was investigated using iso‐solid lines from temperature‐controlled pulse‐NMR along with DSC data, with the rate of cooling of crystallized samples kept constant. The molecular diversity within the fat system was investigated using HPLC and GC. The microstructure of the fats was determined using a temperature‐controlled polarized light microscope, and the polymorphism of the solidified fat structures was determined via a temperature‐controlled X‐ray diffractometer. Hardness was measured by a temperature‐controlled Instron mechanical analyzer with a penetration cone. The phase behavior predicted by the DSC and iso‐solid lines did not account for the hardness trends observed, as the microstructure and polymorphism of the fat also played a significant role. The addition of hard fat to a system did not consistently increase the hardness of the fat system. Furthermore, the solution behavior demonstrated by the iso‐solid line diagram did not account for all trends in melting behavior, as both intersolubility and polymorphic changes occurred simultaneously. it was found that variations in hardness can be inferred from structural changes, although the structural level causing variation differs.
Optimization of reaction conditions for the production of DAG using immobilized 1,3‐regiospecific lipase lipozyme RM IM
Authors: Watanabe Takaaki , Shimizu Masao , Sugiura Masakatsu , Sato Manabu , Kohori Jun , Yamada Naoto , Nakanishi Kazuhiro
Published: November 2006

Oils with a high DAG (1,3‐DAG) content have attracted considerable attention as a healthful food oil component. In this study, we report on the synthesis of 1,3‐DAG from a mixture of FA, constituted largely of oleic and linoleic acids, using an immobilized 1,3‐regioselective lipase from Rhizomucor miehei in a solvent‐free system. The kinetics of 1,3‐DAG production from FA and glycerol were investigated on the basis of a simplified model, taking into consideration the acyl migration reaction, the removal of water, and glycerol dissolution in the oil phase in addition to the esterification reactions. Both the yield of 1,3‐DAG and the purity of DAG were evaluated under a variety of experimental conditions, including reaction temperature, pressure, and amount of enzyme present. When either the reaction temperature or the amount of enzyme used was increased, the 1,3‐DAG production rate increased, but yield remained relatively constant. The 1,3‐DAG yield as well as the purity of DAG gradually decreased because of the enhancement of acyl migration at later stages of the reaction after the 1,3‐DAG concentration reached a maximum. Vacuum was important for attaining high yields of 1,3‐DAG. Under conditions of a high vacuum (1 mm Hg) at 50°C, 1.09 M 1,3‐DAG was produced from 1.29 M glycerol and 2.59 MFA in an 84% yield and in 90% purity.
Calcium coagulation properties of hydrothermally processed soymilk
Authors: Wang C. , Johnson L. A. , Wilson L. A.
Published: November 2006

The effects of hydrothermal cooking (HTC), a steam‐injection process otherwise known as jet cooking, on the calcium salt coagulation properties of soymilk were determined. Full‐fat soymilk was processed at five different conditions (traditional kettle cooking at 100°C for 5 min, HTC at 100°C for 20 s, HTC at 134°C for 26 s, HTC at 154°C for 31 s, and HTC at 162°C for 35 s) and coagulated at four calcium chloride concentrations (0.05, 0.10, 0.20, and 0.30%). Tofu yields and recoveries of dry matter and protein in the coagulated curd followed similar trends with increasing calcium chloride concentration, namely, an initial increase rising to a peak followed by a decrease. HTC‐processed soymilks, especially those processed at high temperature (162°C), gave lower tofu yields and lower recoveries of dry matter and protein in tofu. HTC‐processed soymilks, especially those processed at 134°C or higher, resulted in very soft, fragile, and adhesive tofu. The high calcium salt tolerance of HTC‐processed soymilk might be used to improve dispersion stability of calcium‐fortified soy‐based dairy analogs.
Ouricuri (Syagrus coronata) triacylglycerol analysis using HPLC and positive ion electrospray tandem MS
Authors: Segall S. D. , Artz W. E. , Raslan D. S. , Ferraz V. P. , Takahashi J. A.
Published: November 2006

Among tropical oil sources in Brazil, the ouricuri (Syagrus coronata) tree is nearly ubiquitous. The exact TAG composition of oil from ouricuri fruits was elucidated with electrospray ionization/tandem MS. The oil contains the following FA: caprylic (Cy), capric (Ca), lauric (La), myristic (M), palmitic, stearic, oleic, and linoleic. An estimate of the relative TAG composition based on the neak areas using an ELSD indicated that the four primary TAG—CyLaLa, CaLaLa, CaLaM, and LaLaM—corresponded to 24.3, 19.8, 13.6, and 10.9%, respectively, of the total TAG content.
Zero‐trans shortening using palm stearin and rice bran oil
Authors: Mayamol P. N. , Samuel T. , Balachandran C. , Sundaresan A. , Arumughan C.
Published: November 2006

Several pilot‐scale trials reported in this paper, using palm stearin‐rice bran oil (PS‐RBO) blends, obviously did not contain trans FA (TFA), whereas the commercial products were found to contain 18–27% TFA. The effects of processing conditions such as rate of agitation, crystallization temperature, and composition of the blends on the crystal structure of shortenings were studied. The products were evaluated for their physicochemical characteristics using DSC, X‐ray diffraction (XRD), HPLC, and FTIR techniques. The formulation containing 50% PS and 50% RBO showed melting and cooling characteristics similar to those of hydrogenated commercial “vanaspati” samples. Analysis of the FA composition revealed that the formulated shortenings contained 15–19% C18∶2 PUFA. Tocopherol and tocotrienol contents of the experimental shortenings were in the range of 850–1000 ppm with oryzanol content up to 0.6%. XRD studies demonstrated that the crystal form in the shortenings was predominantly the most stable β′ form, and there was less of the undesirable β form.
Acid‐catalyzed alcoholysis of soybean oil
Authors: Goff Michael J. , Bauer Nicholas S. , Lopes Shailesh , Sutterlin William R. , Suppes Galen J.
Published: November 2006

In an effort to increase utilization of fats and oils with high concentrations of FFA, acid catalysts were investigated at elevated temperatures to determine their efficacy under various operating conditions. Acid‐catalyzed alcoholysis of soybean oil using sulfuric, hydrochloric, formic, acetic, and nitric acids was evaluated at 0.1 and 1 wt% loadings at temperatures of 100 and 120°C in sealed ampules, but only sulfuric acid was effective. Kinetic studies at 100°C, 0.5 wt% sulfuric acid catalyst, and nine times methanol stoichiometry provide >99 wt% conversion of TG in 8 h and less than 0.8 wt% FFA concentrations at less than 4 h. Reaction conditions near 100°C at 0.1 to 0.5 wt% were identified as providing the necessary conversions in a 24‐h batch cycle while not darkening the product as is typical with high temperatures and catalyst loadings. The oxygen/air contained in the reaction ampules at the onset of the reaction was not sufficient to color the product, but the product darkened if atmospheric air contacted the reacting mixture. The presence of small amounts of stainless steel significantly decreased conversions.
Kinetic study of the base‐catalyzed transesterification of monoglycerides from pongamia oil
Authors: Karmee Sanjib Kumar , Mahesh P. , Ravi R. , Chadha Anju
Published: November 2006

The kinetics of the transeterification of vegetable oil is known to follow a three‐step reaction mechanism. The third step involves the transesterification of MG. In this study, the transesterification of MG obtained from crude Pongamia oil was achieved with methanol in the presence of KOH as the catalyst. A MG/methanol ratio of 1∶10 was used at different temperatures (30, 45, 55, and 60°C). 1H NMR was used to monitor the progress of transesterification. The study revealed that the kinetics of this reaction followed a reversible second‐order model, with a good fit obtained for all temperatures except 30°C. This result is explained as arising out of the importance of transport effects at low temperatures. The forward rate constant increased with an increase in temperature, whereas the reverse rate constant showed a decreasing trend, suggesting that the proposed reverse reaction was not an elementary step.
Catalytic epoxidation of methyl linoleate
Authors: Du Guodong , Tekin Aziz , Hammond Earl G. , Wood L. Keith
Published: November 2006

The epoxidation of methyl linoleate was examined using transition metal complexes as catalysts. With a catalytic amount of methyltrioxorhenium (4 mol%) and pyridine, methyl linoleate was completely epoxidized by aqueous H2O2 within 4 h. Longer reaction times (6 h) were needed with 1 mol% catalyst loading. Manganese tetraphenylporphyrin chloride was found to catalyze the partial epoxidation of methyl linoleate. A monoepoxidized species was obtained as the major product (63%) after 20 h.
Kinetics of transesterification of palm‐based methyl esters with trimethylolpropane
Authors: Yunus Robiah , Fakhru'I‐Razi A. , Ooi T. L. , Biak D. R. A. , Iyuke S. E.
Published: November 2006

Kinetics of transesterification of palm‐based methyl esters (POME) with trimethylolpropane (TMP) to polyol esters was investigated. A kinetic model of reaction was obtained by assuming a series of irreversible elementary reactions at various temperatures. The reaction rate constants were determined under limited conditions. The optimal ratios for k2/k1 and k3/k1 were 0.70–0.80 and 0.21–0.25, respectively. Both palm oil methyl esters (PPOME) and palm‐kernel oil methyl esters (PKOME) were reacted with TMP by using sodium methoxide as catalyst. The POME‐to‐TMP molar ratio and catalyst weight percentage were held constant at 10∶1 and 0.4%, respectively. The effects of temperature (70–110°C) and raw materials (PKOME and PPOME) were investigated and found to have a significant impact on the reaction kinetics. When using a large excess of POME and continual withdrawal of methanol via vacuum, the reaction reached completion in less than 20 min at 80°C. After removal of unreacted POME, the final product contained apprximately 98 wt% triesters.
Thiyl radical‐catalyzed isomerization of oils: An entry to the trans lipid library
Authors: Samadi Abdelouahid , Andreu Inmaculada , Ferreri Carla , Dellonte Sergio , Chatgilialoglu Chryssostomos
Published: November 2006

The unsaturated fatty acyl moieties of TAG present in natural oils of borage, olive, and rice were converted to their corresponding geometrical trans isomers by thiyl radical‐catalyzed isomerization. Thiyl radicals were generated from 2‐mercaptoethanol under photolytic or thermal conditions. A relevant feature of this method is the absence of double‐bond shifts, so that no positional trans isomers or conjugated polyenes are formed. Oils obtained after the isomerization were winterized to further increase their trans fatty acid content. Methanolysis and hydrolysis of the trans oil mixtures using an enzymatic method (lipase B from Candida antarctica) gave good conversions to the corresponding trans FAME and fatty acids, respectively. These results are relevant for the studies of lipid isomerism and trans fatty acid recognition, which is a growing concern in biochemistry and nutrition, and open new perspectives for the synthesis of glycerides and studies of their structure‐activity relationships.
Frying stability of high‐oleate and regular soybean oil blends
Authors: Su Caiping , White Pamela
Published: November 2006

The objective of this work was to study the frying stability of soybean oil (SBO) with reduced linoleate (18∶2) and linolenate (18∶3) and elevated oleate (18∶1) contents. High‐oleate SBO [HO SBO, 79% oleic acid (OA)] and a control (conventional SBO, 21.5% OA) were tested as is, as well as blended in different ratios to make three blended oils containing 36.9, 50.7, and 64.7% OA, abbreviated as 37%OA, 51%OA, and 65%OA, respectively. In addition, a low‐linolenate (LL) SBO containing 1.4% 18∶3 and 25.3% 18∶1 was tested. Bread cubes (8.19 cm3) were fried in each of 18 oils (6 treatments×3 replicates). We hypothesized that stability indicators would be indirectly related to the total 18∶2 plus 18∶3 percentages and/or the calculated oxidizability. In general, the results were fairly predictable based on total 18∶2 and 18∶3 concentrations. The overall frying stability of the six oil treatments, from the best to the poorest, was: 79%OA, 65%OA, 51%OA, LL≥37%OA, and the control, with respective total compositions for 18∶2 plus 18∶3 of 10.3, 23.6, 36.3, 59.6, 48.9, and 62.8%. The greatly reduced concentration of 18∶3 in the LL SBO made it more stable than the 37%OA, even though the combined composition of 18∶2 and 18∶3 of LL was greater than that of the 37%OA. Blending conventional SBO with HO SBO had a profound effect on the oxidative stability index and color of the blended oils, but the values were not linearly predictable by the percentage of control in the blended oil. Other stability indices, including calculated oxidizability, calculated iodine value, conjugated dienoic acid value, and viscosity, changed in linear response to an increased proportion of the control in the blends.
The pseudo‐single‐phase, base‐catalyzed transmethylation of soybean oil
Authors: Mao Vinnie , Konar Samir K. , Boocock David G. B.
Published: November 2006

The base‐catalyzed transmethylation of soybean oil has been studied under conditions whereby the reaction starts as a single phase, but later becomes two phases as glycerol separates. Methanol/oil molar ratios of 6∶1 were used at 23°C. The catalysts were sodium hydroxide (0.5, 1.0, and 2.0 wt%), potassium hydroxide (1.0 and 1.4 wt%), and sodium methoxide (0.5, 1.0, and 1.35 wt%), all concentrations being with respect to the oil. Oxolane (tetrahydrofuran) was used to form a single reaction phase. The reactions deviated from homogeneous kinetics as glycerol separated, taking with it most of the catalyst. When 1.0 wt% sodium hydroxide was used, the methyl ester content reached 97.5 wt% after 4 h, compared with 85–90 wt% in the two‐phase reaction. Sodium hydroxide (1.0 wt%), sodium methoxide (1.35 wt%), and potassium hydroxide (1.4 wt%) gave similar results, presumably because the same number of moles was used. The ASTM biodiesel specification for chemically bound glycerol was achieved after only 3 min when 2.0 wt% sodium hydroxide was used. However, the standard was not achieved after 4 h when 1.0 wt% sodium hydroxide was used, the MG content being 1.1–1.6 wt%. The use of 2.0 wt% catalyst is commercially impractical.
Quality loss related to rancidity development during frozen storage of horse mackerel (Trachurus trachurus)
Authors: Aubourg Santiago P. , Piñeiro Carmen , González M Jesús
Published: November 2006

The development of rancidity and its effect on quality loss were studied in frozen horse mackerel (Trachurus trachurus). Two different kinds of fish products (whole fish and fillets) were stored at a commercial freezer temperature (−20°C) for up to 12 mon and were compared to samples stored at a much lower temperature (−80°C). Analyses included: lipid hydrolysis (FFA formation) and oxidation (PV, thiobarbituric acid index, fluorescent compound formation), loss of endogenous antioxidant (α‐tocopherol), protein changes (electrophoretic analysis of sarcoplasmic and SDS‐soluble fractions), and sensory analysis (skin, eyes, gills, flesh odor, consistency, flesh appearance). According to biochemical indices, fillets stored at −20°C showed susceptibility to rancidity development, leading to a shelf life of 1 mon, whereas whole fish at the same temperature were still edible at month 5. The use of a low temperature (−80°C) inhibited rancidity development, leading to good‐quality (whole fish) and fairquality (fillets) fish products at the end of the experiment. The application of protective treatments especially designed to prevent lipid oxidation is encouraged when commercializing this species in the frozen state.
Preparation of soy protein concentrate and isolate from extruded‐expelled soybean meals
Authors: Wang H. , Johnson L. A. , Wang T.
Published: November 2006

Soy protein concentrates (SPC) and soy protein isolates (SPI) were produced from hexane‐defatted soy white flakes and from two extruded‐expelled (EE) soy protein meals with different degrees of protein denaturation. Processing characteristics, such as yield and protein content, and the key protein functional properties of the products were investigated. Both acid‐and alcohol‐washed SPC from the two EE meals had higher yields but lower protein contents than that from white flakes. Generally, SPC from an acid wash had much better functional properties than those from an alcohol wash. The SPI yield was highly proportional to the protein dispersibility index (PDI) of the starting material, so the EE meal with lower PDI had lower SPI recovery. The protein content in SPI prepared from EE meals was about 80%, which was lower than from white flakes. Nevertheless, SPI from EE meals showed functional properties similar to or better than those from white flakes. The low protein contents in SPC and SPI made from EE meals were mainly due to the presence of residual oil in the final products. SPI made from EE meals had higher concentration of glycinin relative to β‐conglycinin than that from white flakes.
The interaction of macrophage receptors with bacterial ligands
Authors: Plüddemann Annette , Mukhopadhyay Subhankar , Gordon Siamon
Published: November 2006

Innate immune receptors play a key role in the early recognition of invading bacterial pathogens and initiate the crucial innate immune response. The diverse macrophage receptors recognise Gram-positive and Gram-negative bacteria via conserved structures on the bacterial surface and facilitate phagocytosis and/or signalling, providing the trigger for the adaptive immune response. These receptors include scavenger receptors, C-type lectins, integrins, Toll-like receptors and siglecs. The bacterial ligands generally recognised by these receptors range from lipopolysaccharides on Gram-negative bacteria to peptidoglycan and lipoteichoic acid on Gram-positive bacteria. However, emerging evidence indicates that bacterial proteins are also important ligands; for example, surface proteins from Neisseria meningitidis have been shown to be ligands for class A scavenger receptors. In addition, a group of cytosolic receptors, the NBS-LRR proteins, have been implicated in recognition of bacterial breakdown products. It is becoming increasingly apparent that macrophage receptors can act in conjunction with one another to deliver an appropriate response.
Medical law and the power of life and death
Authors: Veitch Kenneth
Published: November 2006

The purpose of this article is to offer an analysis of the nature of contemporary legal power over the ending of human life in medical contexts. Drawing on Michel Foucault’s characterisations of power relations in the sphere of life and death in The History of Sexuality, Vol. I, it is argued that, in its current regulation of the ending of human life in this area, law displays elements of two of those modes, or forms, of power identified by Foucault – the juridical and the disciplinary. This argument is illustrated by reference to two recent cases – Re A (Children) and Re B (an adult: refusal of medical treatment) – and set against a background of shifting modes of governmentality (here, the movement from medicalisation to legalisation). Through an analysis of the forms of legal power in this particular context, the article also has a broader purpose – to advance an alternative approach to the question of power within the academic medical law field. Specifically, unlike the standard form of legal academic inquiry in this area – that is, one which is driven mainly by a concern for ethics and resolving ethical dilemmas – it is suggested that an appreciation of the importance that institutional context(s) and requirements play in medical law is necessary if we are to understand fully both the factors constitutive of legal power and the subtle, and often controversial, effects that flow from the manner in which it is exercised and asserted.
A culture of retribution: symbolic violence in legal and literary discourses on juvenile delinquency
Authors: Quéma Anne
Published: November 2006

This article seeks to establish law and literature as two distinct yet interacting fields through which the norms of a particular culture are filtered. Drawing on Pierre Bourdieu’s sociological theory, it suggests that legal and literary statements are contextualised by norms and values that exert symbolic violence to the extent that, through communication and knowledge, they define social subjects and their material practices. The specific objective of this article is to map out the network of relationships between the apparently separate fields of the Children and Young Persons Act 1933 and the Criminal Justice Act 1948 and Alan Sillitoe’s The Loneliness of the Long-Distance Runner, and to understand the ways in which law and literature related to symbolic violence as they created, maintained or countered norms which constituted the English culture of juvenile offenders in the 1950s.
Three‐dimensional dense strong motion waveform inversion for the rupture process of the 1999 Chi‐Chi, Taiwan, earthquake
Authors: Lee Shiann‐Jong , Ma Kuo‐Fong , Chen How‐Wei
Published: November 2006

We inverted the high‐resolution spatiotemporal slip distribution of the 21 September 1999 Chi‐Chi, Taiwan, earthquake utilizing data from densely distributed island‐wide strong motion stations for a three‐dimensional (3‐D) fault geometry, and 3‐D Green's functions calculations based upon parallel nonnegative least squares inversion. The 3‐D fault geometry, consistent with high‐resolution reflection profile, is determined from GPS inversion and aftershocks distribution. This 3‐D fault model presents the dip angle gradually becoming shallower from south to north along the fault and near flat at the deeper portion of the fault. The 3‐D Green's functions are calculated through numerical wavefield simulation from three‐dimensional heterogeneous velocity structure derived from tomography studies. The Green's functions show significant azimuthal variations and suggest the necessity of lateral heterogeneity in velocity structure. Considering complex fault geometry and Green's functions in full 3‐D scale, we invert the spatial/temporal slip distribution of the 1999 Chi‐Chi earthquake using the best available and most densely populated strong motion waveform data. We perform the inversion under a parallel environment utilizing multiple‐time window to manage the large data volume and source parameters. Results indicate that most slip occurred at the shallower portion of the fault above the decollement. Two major asperities are found, one in the middle of the fault and another one at the northern portion of the fault near the bend in the fault trace. The slip in the southern portion of the fault shows a relatively low slip rate with longer time duration, while the slip in the northern portion of the fault shows a large slip rate with shorter time duration. The synthetics explain the observations well for the island‐wide distributed strong motion stations. This comprehensive study emphasizes the importance of realistic fault geometry, 3‐D Green's functions, and parallel inversion technique in correctly accounting for both the detailed source rupture process and its relationship with the strong ground motion of this intense earthquake.
Surfactants and submicron sea spray generation
Authors: Sellegri K. , O'Dowd C. D. , Yoon Y. J. , Jennings S. G. , de Leeuw Gerrit
Published: November 2006

Laboratory experiments have been carried out to elucidate the role of surfactants on the primary marine aerosol production of submicron marine aerosols. A synthetic surfactant SDS was used in conjunction with artificially generated seawater, and the resultant bubble‐mediated aerosol produced was observed. At 23°C, the aerosol distribution resulting from the use of surfactant‐free seawater comprised three modes: (1) a dominant accumulation mode at 110 nm; (2) an Aitken mode at 45 nm; and (3) a third mode, at 300 nm, resulting from forced bursting of bubbles. The forced bursting occurs when bubbles fail to burst upon reaching the surface and are later shattered by splashing associated with breaking waves and/or wind pressure at the surface. At 4°C, the accumulation mode diameter was reduced to 85 nm, the Aitken mode diameter was reduced to <30 nm and the 300 nm mode diameter was reduced to 200 nm. With the addition of SDS, the relative importance of the mode resulting from forced bursting increased dramatically. The laboratory results were compared to the observed seasonality of North Atlantic marine aerosol where a progression from mode radii minima in winter to maxima in summer is seen. The bimodality and the seasonality in modal diameter can be mostly explained by a combination of the three modes observed in the laboratory and their variation as a function of sea‐surface temperature and seawater surfactant concentration. These results indicate that submicron primary aerosol modes would on a first approximation result from bubble bursting processes, although evidences of additional secondary processes leading, during summer, to a higher amplitude of the Aitken mode and mode 2 smoothed into mode 3 still need to be investigated.
Summer carbon dioxide and water vapor fluxes across a range of northern peatlands
Authors: Humphreys Elyn R. , Lafleur Peter M. , Flanagan Lawrence B. , Hedstrom Newell , Syed Kamran H. , Glenn Aaron J. , Granger Raoul
Published: November 2006

Northern peatlands are a diverse group of ecosystems varying along a continuum of hydrological, chemical, and vegetation gradients. These ecosystems contain about one third of the global soil carbon pool, but it is uncertain how carbon and water cycling processes and response to climate change differ among peatland types. This study examines midsummer CO2 and H2O fluxes measured using the eddy covariance technique above seven northern peatlands including a low‐shrub bog, two open poor fens, two wooded moderately rich fens, and two open extreme‐rich fens. Gross ecosystem production and ecosystem respiration correlated positively with vegetation indices and with each other. Consequently, 24‐hour net ecosystem CO2 exchange was similar among most of the sites (an average net carbon sink of 1.5 ± 0.2 g C m−2 d−1) despite large differences in water table depth, water chemistry, and plant communities. Evapotranspiration was primarily radiatively driven at all sites but a decline in surface conductance with increasing water vapor deficit indicated physiological restrictions to transpiration, particularly at the peatlands with woody vegetation and less at the peatlands with 100% Sphagnum cover. Despite these differences, midday evapotranspiration ranged only from 0.21 to 0.34 mm h−1 owing to compensation among the factors controlling evapotranspiration. Water use efficiency varied among sites primarily as a result of differences in productivity and plant functional type. Although peatland classification includes a great variety of ecosystem characteristics, peatland type may not be an effective way to predict the magnitude and characteristics of midsummer CO2 and water vapor exchanges.
Conduit diameter and buoyant rising speed of mantle plumes: Implications for the motion of hot spots and shape of plume conduits
Authors: Steinberger B. , Antretter M.
Published: November 2006

Mantle plumes are expected to be affected by large‐scale flow in the Earth's mantle related to plate motions, subducted slabs, and possibly large‐scale upwellings. Motion of plume conduits will depend on both large‐scale flow and buoyant rising speed of the conduit through the mantle. Here we present a model of depth‐dependent plume conduit temperature, viscosity, radius, and buoyant rising speed and use it to compute plume and hot spot motion. Results support a temperature anomaly of about 500 K at the plume base. In this case, sublithospheric temperature anomaly is about 150 K for the Iceland plume; transition zone anomaly is between 150 and 200 K for Iceland, about 250 K for Samoa, and about 300 K for Hawaii. Thermal plume radii are about 100 km in the upper mantle, increasing to about 200 km in the lower mantle. Beneath the lithosphere, viscosity in the vicinity of plumes is substantially reduced compared to the underlying mantle, and fast‐moving plates deflect plumes by 200 km or less, corresponding to a plume conduit buoyant rise time of about 3 Myr between 400 and 100 km depth, where most of the shear flow due to plate motions occurs. During 100 Myr, plume conduits rise buoyantly from about 1500–2000 km depth. In many cases, computed hot spot motion agrees with previous computations: south‐southeastward motion of the Hawaiian hot spot during the past 100 Myr, Louisville hot spot motion in a similar direction but at slower speed during the past 50 Myr, and westward motion of the Easter hot spot relative to Hawaii and Louisville. However, the previously computed substantial southward motion of the Kerguelen hot spot is not confirmed. If plume sources in the lowermost mantle are assumed to move with large‐scale flow, they are predicted to be displaced toward the two large‐scale upwellings beneath Africa and the Pacific relative to hot spot surface locations. For fixed sources, predicted tilts of the lower part of conduits tend to be opposite to that.
A low velocity belt beneath northern and eastern Tibetan Plateau from Pn tomography
Authors: Liang Chuntao , Song Xiaodong
Published: November 2006

New Pn tomography on Tibetan Plateau (TP) and neighboring region is conducted with data assembled from various sources. The improved Pn tomographic image delineates several distinct geophysical regimes that are approximately separated by geological boundaries at surface. Dense distribution of the stations in the eastern half of the plateau allows us to infer a 3D view of crustal thickness variation of the region. The most striking feature is the bended low velocity belt (LVB), which extends from west to east beneath Qiangtang block and Songpan Ganzi fold belt (SGFB) in northern TP and then turns consistently southward with SGFB beneath eastern TP and further south to Indo‐China. The consistency between geological boundaries on surface and sharp velocity contrast boundaries in uppermost mantle may suggest strong deformation coupling between crust and, at least uppermost mantle, if not whole lithosphere. A north‐south striking LVB is also observed cutting through the southern TP, coinciding with the Yadong‐Gulu rift at surface. Our tomographic results are generally consistent with dynamic models that involve with underthrusting in the southern TP, shortening in the northern TP, and extrusion to the east and the southeast. Furthermore, our results suggest significant east‐west variations in the structure and dynamics.
Contribution of charge exchange loss to the storm time ring current decay: IMAGE/HENA observations
Authors: Keika K. , Nosé M. , Brandt P. C. , Ohtani S. , Mitchell D. G. , Roelof E. C.
Published: November 2006

The present study addresses the contribution of charge exchange loss of the ring current ions to the decay of the storm time ring current, based on measurements of energetic neutral atoms (ENAs) made by the High Energy Neutral Atom (HENA) imager on board the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE) satellite. The energy range of ENA fluxes examined in the present study is from 27 to 119 keV for hydrogen and from 79 to 264 keV for oxygen. This is the first statistical estimate of the charge exchange contribution made with dedicated measurements of both neutral hydrogen and oxygen. We estimate charge exchange energy losses of the ring current ions, employing two independent methods. The decay rate of the ring current is derived from the temporal variations of the Dst index. Our estimates show that the rate of the charge exchange energy losses is comparable to the ring current decay rate for the intervals of the slow decay, while the loss rate is much smaller than the decay rate in the rapid decay phase in particular for the early stage of a storm recovery. The logarithm of the energy loss rate is well correlated with the simultaneous Dst index, increasing as Dst decreases. Utilizing the high correlations, we simulate a Dst recovery due to charge exchange loss alone. Pressure‐corrected Dst (Dst0) recoveries derived from measured Dst cannot be reproduced by charge exchange loss alone. We conclude that the charge exchange loss is not primarily responsible for the rapid decay of the storm time ring current.
Comparison between nighttime ionosonde, incoherent scatter radar, AE‐E satellite, and HF Doppler observations ofFregion vertical electrodynamic plasma drifts in the vicinity of the magnetic equator
Authors: Oyekola Oyedemi S.
Published: November 2006

NighttimeFregion vertical drifts were made using an ionosonde for the equatorial station Ibadan (7.4°N, 3.9°E, 6°S dip) from 1 year of data during 1957–1958 International Geophysical Year (IGY) that corresponds to a period of solar maximum for undisturbed condition. We compare the seasonal vertical drifts with measurements made by incoherent scatter radar, AE‐E satellite, and HF Doppler for equatorialFregion vertical drifts. We find a comparable variability pattern during periods of highFlayer heights during equinox and the December solstice, and the opposite behavior occurs during June solstice. The drifts are predominantly downward between 2000 and 0500 LT intervals. Ionosonde drifts are smaller in values by either a factor of two or three than other methods, except for consistent June solstice ionosonde and satellite magnitudes. The equinoctial average prereversal enhancements measured by the four techniques are roughly comparable (about 36 m/s) and occur at the same local time (1900 LT) for all the seasons. The evening reversal times are similar, apart from June solstice that exhibits large variations. The morning reversal times are also in accord except for the equinoctial Jicamarca drift. Our observations indicate that ionosonde drifts measurements are in better agreement with vertical drifts results at other equatorial stations.
Contemporary deformation of the Wasatch Fault, Utah, from GPS measurements with implications for interseismic fault behavior and earthquake hazard: Observations and kinematic analysis
Authors: Chang Wu‐Lung , Smith Robert B. , Meertens Charles M. , Harris Ron A.
Published: November 2006

Contemporary strain accumulation rates of the 350‐km‐long Wasatch fault, Utah, have been determined by GPS measurements and provide key data for evaluating normal fault behavior and related earthquake hazard assessment. This paper presents a complete description of the Wasatch GPS network, data archiving and processing, and the measured ground deformation. The network spans the Wasatch fault in an area ∼300‐km long and ∼200‐km wide in north and central Utah and consists of 43 GPS sites surveyed in 1992, 1993, 1994,1995, 1999, 2001, and 2003, plus 8 permanent GPS stations operating continuously beginning 1997. Observations across a 65‐km wide area centered on the Wasatch fault indicate the principal horizontal extension rate of 24 ± 6 nstrain/yr with the direction nearly perpendicular to the fault. This strain rate corresponds to a horizontal displacement rate of 1.6 ± 0.4 mm/yr, accommodating ∼50% of the crustal deformation across the ∼200 km‐wide eastern Basin‐Range. Analysis of the spatial variation of the strain‐rate field reveals that the strain accumulation is concentrated near the Wasatch fault, which suggests an abrupt transition in the horizontal deformation at the fault between the eastern Basin‐Range and the Rocky Mountains. We employed a finite‐strain model that accounts for simple‐shear deformation of the hanging‐wall to compare horizontal extension rates measured by GPS with vertical fault‐displacement rates determined by geologic data. Our results suggest that the average Holocene strain‐release rate is higher than the contemporary strain‐loading rate for the Wasatch fault if the fault dips less than 30°W, but these two rates are consistent if the fault dips more steeply.
Water‐soluble organic carbon and oxalate in aerosols at a coastal urban site in China: Size distribution characteristics, sources, and formation mechanisms
Authors: Huang Xiao‐Feng , Yu Jian Zhen , He Ling‐Yan , Yuan Zibing
Published: November 2006

Water‐soluble organic compounds in aerosol contribute a significant fraction to organic aerosol mass and influence interactions of aerosols with water in the atmosphere. Despite their importance, the sources and formation mechanisms of these compounds are not well understood. In this work, we measured the size distributions of water‐soluble organic carbon (WSOC) and its most abundant single component, oxalate, in the urban area of Shenzhen, a coastal metropolitan city in southern China. In the cloud condensation nuclei size range, organic compounds were found to constitute a significant fraction (roughly one half) of the total water‐soluble substance mass. The positive matrix factorization (PMF) model was used to resolve the bulk mass size distributions into condensation, droplet, and coarse modes, with their respective modal peak at 0.4, 1.0, and 5.5 μm. Both WSOC and oxalate had a dominant droplet mode, a minor condensation mode, and a minor coarse mode. Approximately one half of WSOC and two thirds of oxalate mass were in the droplet mode. The sources and formation mechanisms of oxalate and WSOC were inferred in reference to the well‐understood size distribution characteristics of inorganic species (Ca2+, Na+, K+, and SO42−), in conjunction with source identification and contribution estimation by PMF. We found that the droplet mode oxalate was mostly produced from in‐cloud aqueous phase reactions. Among significant sources contributing to the total WSOC were biomass burning, in‐cloud processing, soil dust particles, and aged sea salt particles. The first two sources were the major contributors to the droplet WSOC, while the latter two were responsible for the coarse mode WSOC. The droplet mode WSOC correlated well with K+ and sulfate, consistent with the source estimates by PMF. Future work on WSOC is suggested to be directed at characterizing the biomass burning aerosols and elucidating the molecular formation pathways in the aqueous phase.
Analysis of the isoprene chemistry observed during the New England Air Quality Study (NEAQS) 2002 intensive experiment
Authors: Roberts James M. , Marchewka Mathew , Bertman Steven B. , Goldan Paul , Kuster William , de Gouw Joost , Warneke Carsten , Williams Eric , Lerner Brian , Murphy Paul , Apel Eric , Fehsenfeld Fred C.
Published: November 2006

Isoprene and its first and second generation photochemical products, methyl vinyl ketone (MVK), methacrolein (MACR), and peroxymethacrylic nitric anhydride (MPAN), were measured off the coast of New England during the 2002 New England Air Quality Study (NEAQS) on board the NOAA Research Vessel Ronald H. Brown. The results of these measurements were analyzed using a simple sequential reaction model that has been used previously to examine regional oxidant chemistry. The highest isoprene impact was observed in air masses that had passed over an area of high isoprene emission WSW of Boston. The relative concentrations of isoprene and its first generation products show that the photochemistry is consistently “older” than the isoprene photochemistry observed at continental sites. The sequential reaction model was also applied to the aldehyde‐PANs (Peroxycarboxylic nitric anhydride) system, and the resulting PPN (peroxypropionic nitric anhydride)/propanal and PAN (peroxyacetic nitric anhydride)/acetaldehyde relationships were consistent with additional sources of PAN in this environment, e.g., isoprene photochemistry. This isoprene source was estimated to result in approximately 1.6 to 4 times more PAN in this environment relative to that produced from anthropogenic VOCs (volatile organic compounds) alone.
Geologic constraints on crustal plateau surface histories, Venus: The lava pond and bolide impact hypotheses
Authors: Hansen Vicki L.
Published: November 2006

Venusian crustal plateau formation is hotly debated. Crustal plateaus are large (∼1500–2500 km) quasi‐circular ∼0.5‐ to 4‐km‐high plateaus that host distinctive tectonic fabrics, called ribbon tessera. Debate centers on plateau support and fabric formation. Detailed geologic mapping of an ∼360,000 km2 region, eastern Ovda Regio, provides critical clues for plateau evolution. Ribbon‐tessera fabrics record broadly synchronous layer contraction, extension, and flooding, as an initially strong, thin layer (<100 m) developed across Ovda. As the layer underwent ductile shortening and brittle extension, subsurface lava flooded structural lows. With progressive deformation the layer thickened, leading to formation of progressively longer‐wavelength structures. Early‐formed shorter‐wavelength structures and lava‐ filled valleys were carried piggyback on longer‐wavelength folds. This history indicates an extremely large strength contrast that is inconsistent with a conductive geotherm, reflecting instead the presence of a near‐surface molten layer. I propose the lava‐pond hypothesis: Ribbon‐tessera fabrics represent progressively solidified “scum” of a huge lava pond, leading to crustal plateau formation. I further propose that individual lava ponds formed as a result of large bolide (∼20–30 km diameter) impact with ancient thin lithosphere, causing massive partial melting in the upper mantle. Melt rose buoyantly to form huge (∼1500–2000 km diameter) lava ponds, completely resurfacing the local area. In the upper mantle depleted residuum would be compositionally more buoyant and stronger than adjacent undepleted mantle. Isostatic adjustment resulted in pond uplift and plateau formation. Subsequent secular cooling could “freeze” a plateau in place, or mantle convection could strip away the residuum root, leading to plateau collapse.
STN Stimulation Alters Pallidal—Frontal Coupling during Response Selection under Competition
Authors: Thobois Stéphane , Hotton Gary R , Pinto Serge , Wilkinson Leonora , Limousin-Dowsey Patricia , Brooks David J , Jahanshahi Marjan
Published: November 2006

To investigate the effects of bilateral subthalamic nucleus (STN) stimulation on patterns of brain activation during random number generation (RNG), a task that requires suppression of habitual counting and response selection under competition. We used [Formula: see text] positron emission tomography to investigate the changes of regional cerebral blood flow (rCBF) induced by bilateral STN stimulation during a RNG task, in six patients with Parkinson's disease. Paced RNG at 1 Hz was compared with a control counting task. Both tasks were performed off medication with deep brain stimulation on and off. Subthalamic nucleus stimulation had a negative effect on performance of fast-paced RNG, leading to reduced randomness and increased habitual counting. Subthalamic nucleus stimulation also induced a reduction of rCBF in the left dorsal frontal gyrus, inferior frontal gyrus, dorsolateral prefrontal cortex, posterior and right anterior cingulate, and an increase of rCBF in the right internal globus pallidum (GPi) during RNG. Stimulation of the STN significantly altered pallidal coupling with frontal and temporal areas compared with when the stimulators were off. In conclusion, during RNG: (i) STN stimulation activates its output neurons to the GPi; (ii) STN stimulation induces increased inhibition of a prefrontal—cingulate network. This is the first direct evidence that STN stimulation significantly alters pallidal coupling with prefrontal, cingulate, and temporal cortices during performance of a task that requires response selection under competition.
Gabor Schauder bases and the Balian-Low theorem
Authors: Heil Christopher , Powell Alexander M.
Published: November 2006

The Balian-Low Theorem is a strong form of the uncertainty principle for Gabor systems that form orthonormal or Riesz bases for L2(R). In this paper we investigate the Balian-Low Theorem in the setting of Schauder bases. We prove that new weak versions of the Balian-Low Theorem hold for Gabor Schauder bases, but we constructively demonstrate that several variants of the BLT can fail for Gabor Schauder bases that are not Riesz bases. We characterize a class of Gabor Schauder bases in terms of the Zak transform and product A2 weights; the Riesz bases correspond to the special case of weights that are bounded away from zero and infinity.
C
60
in intense short pulse laser fields down to 9fs: Excitation on time scales below e-e and e-phonon coupling
Authors: Shchatsinin Ihar , Laarmann Tim , Stibenz Gero , Steinmeyer Günter , Stalmashonak Andrei , Zhavoronkov Nick , Schulz Claus Peter , Hertel Ingolf V.
Published: November 2006

The interaction of C60 fullerenes with 765–797nm laser pulses as short as 9fs at intensities of up to 3.7×1014Wcm−2 is investigated with photoion spectroscopy. The excitation time thus addressed lies well below the characteristic time scales for electron-electron and electron-phonon couplings. Thus, energy deposition into the system is separated from energy redistribution among the various electronic and nuclear degrees of freedom. Insight into fundamental photoinduced processes such as ionization and fragmentation is obtained from the analysis of the resulting mass spectra as a function of pulse duration, laser intensity, and time delay between pump and probe pulses, the latter revealing a memory effect for storing electronic energy in the system with a relaxation time of about 50fs. Saturation intensities and relative abundances of (multiply charged) parent and fragment ions (C60q+, q=1–6) are fingerprints for the ionization and fragmentation mechanisms. The observations indicate that for final charge states q>1 the well known C60 giant plasmon resonance is involved in creating ions and a significant amount of large fragments even with 9fs pulses through a nonadiabatic multielectron dynamics. In contrast, for energetic reasons singly charged ions are generated by an essentially adiabatic single active electron mechanism and negligible fragmentation is found when 9fs pulses are used. These findings promise to unravel a long standing puzzle in understanding C60 mass spectra generated by intense femtosecond laser pulses.
Study of the mechanism of overlays acting on laser shock waves
Authors: Zhang Yongkang , Gu Yongyu , Zhang Xingquan , Shi Jianguo , Zhou Jun
Published: November 2006

In laser shock processing, overlays are used to enhance peak pressures and prolong pulse widths of laser shock waves. The overlay usually has three types: rigid, flexible, and liquid overlays. In this paper, some mathematical models are constructed to analyze the process of laser-induced shock waves and pressure attenuations of the shock waves. The analyses indicate that the peak pressure of shock waves depends on the deformation amount of the overlays and the pressure attenuations depend on the deformation speed of the overlays, while the deformation amount and deformation speed are determined by the density and thickness of the overlays. Besides, for the rigid overlay, the elastic modulus must be taken into account in addition to its density and thickness. Furthermore, the reflected waves from the overlays enhance the shocking effects of laser-induced shock waves. Therefore, the rigid overlays are superior to the flexible and liquid overlays.