bluuebunny/crossref_metadata_2025 huggingface dataset:
Packing of polyethylene oxide chains in a mixed micelle
Authors: Meguro K. , Akasu H. , Ueno M.
Published: March 2007

The effects of an anionic surfactant, sodium dodecyl sulfate (SDS), on the micellar properties of a nonionic surfactant such as homogeneous heptaethylene glycol n‐dodecyl ether (7ED) have been studied by the charge transfer solubilization of 7,7,8,8‐tetracyanoquinodimethane, pNa, and electric conductivity measurements. Attention has been paid to changes in packing of polyethylene oxide chains in the mixed micelle and to binding of the counterions onto the micelle surface. All measurements were made on solutions ranging in 7ED concentration from 1 × 10−6 to 1×10−1 M, while the SDS concentration was maintained constant. It has been shown that the binding of Na+ ions to the mixed micelle occurs in the 7ED concentration region where the packing of polyethylene oxide chains in the micelle is loose, while release of Na+ ions is observed when the packing is compact. The results of electric conductivity correspond well with those mentioned above. However, in the region of high 7ED concentration, the decreasing mobility of the mixed micelles affects the electric conductivity more than the increasing degree of ionic dissociation of the micelle.
A study of rice bran oil refining
Authors: Hartman L. , Dos Reis M. I. J.
Published: March 2007

Examination of a number of rice bran oils revealed the presence of monoglycerides (0.5–1.4%) and other hydroxylated compounds such as diglycerides and glucosides. The hydroxyl numbers of the samples ranged from 8.5 to 27, depending on their acidity. On the assumption that the inordinately high refining losses of rice bran oil are due, along with the acidity, to the presence of hydroxylated compounds, the hydroxyl numbers of several samples of that oil were reduced by progressive acetylation with acetic anhydride. This was accompanied by gradual reduction of the refining losses, which seems to support the above mentioned assumption.
Epoxy allylic carbocations as conceptual intermediates in the biogenesis of diverse marine oxylipins
Authors: Gerwick William H.
Published: March 2007

Marine organisms, especially marine algae, are extremely rich in a diversity of novel oxylipin structures. Many of these oxylipins contain functionalities and rings of a type and location unknown in mammalian systems. In this perspective reviewing marine oxylipins, a proposal is formulated for the central intermediacy of an epoxy allylic carbocation in the biogenesis of these diverse structures. This proposal is strengthened by the relatively large number of examples which are consistent with this type of mechanistic transformation.
Purification and characterization of a 28 kDa cytosolic inhibitor of cholesteryl ester hydrolases in rat testis
Authors: Hines Denise S. , Wee Siowfong , Grogan W. McLean
Published: March 2007

A 28 kDa inhibitory protein was purified from ratestis cytosol by sequential 40–65% ammonium sulfate precipitation, cation exchange chromatography, anion exchange chromatography, and preparative SDS‐polyacrylamide gel electrophoresis. The heat‐stable, trypsin‐labile protein exhibited nonenzymatic, concentration‐dependent inhibition of testicular and pancreatic cholesteryl ester hydrolases at all stages of putification. Copurifying at each stage was a 26.5 kDa protein which comprised 25% of the mass of the two proteins. Polyclonal antibodies raised to either or both 28 kDa and 26.5 kDa proteins by direct injection of excised electrophoretic bands cross‐reacted with both proteins on western blots, immunoprecipitated both proteins, and neutralized inhibitory activity. Amino acid compositions of the individual proteins electroeluted from SDS‐polyacrylamide gels were different from those of other surface‐active proteins of similar molecular weights. Both proteins exhibited identical pl of 4.8 on chromatofocusing columns and two‐dimensional gel electrophoresis. Although the subcellular distribution of the 28 kDa protein is unknown, its testicular cytosolic concentration, calculated from the purified protein mass, was 8×10−9 mols/L, which probably underestimates the actual concentration by an order of magnitude. This is greater than the minimum concentration required forin vitro inhibition (10−9 mols/L), consistent with a physiological role for this protein.
Oxidation products of cyanidin 3‐O‐β‐d‐glucoside with a free radical initiator
Authors: Tsuda Takanori , Ohshima Katsumi , Kawakishi Shunro , Osawa Toshihiko
Published: March 2007

Recently, we have reported that anthocyanins show strong antioxidative activity, but no attention has been paid to anthocyanins from the viewpoint of the reaction mechanism of alkylperoxyl radicals; therefore, we investigated the reaction products of antioxidative anthocyanins (cyanidin 3‐O‐β‐d‐glucoside). Cyanidin 3‐O‐β‐d‐glucoside was reacted with 2,2′‐azobis(2,4‐dimet hylvaleronitrile) to generate the alkylperoxyl radicals, and the reaction products were isolated by high‐performance liquid chromatography. The products were identified as 4,6‐dihydroxy‐2‐O‐β‐d‐glucosyl‐3‐oxo‐2,3‐dihydrobenzofuran and protocatechuic acid. Based on reaction products, the antioxidative mechanism of cyanidin 3‐O‐β‐d‐glucoside may be different from that of α‐tocopherol; cyanidin 3‐O‐β‐d‐glucoside would produce another radical scavenger, as it would break down the structure and scavenge the radicals.
Increased formation of phosphatidylinositol‐4‐phosphate in human platelets stimulated with lysophosphatidic acid
Authors: Mani Indu , Gaudette Douglas C. , Holub Bruce J.
Published: March 2007

Lysophosphatidic acid (LPA, 1‐acyl‐sn‐glycerol 3‐phosphate), at a concentration of 1–40 µM, was found to induce the formation of [3H]inositol‐labelled phosphatidylinositol‐4‐phosphate (PIP) without significantly altering the levels of either phosphatidylinositol (PI) or phosphatidylinositol bisphosphate (PIP2) in washed human platelets. Preincubation of platelets with the cyclooxygenase/lipoxygenase inhibitor, BW755C at 100 µM, did not alter the LPA‐induced formation of PIP. Activation of platelets with the phorbol ester, phorbol 12‐myristate 13‐acetate (PMA), elicited a similar response (induction of PIP formation). The specific protein kinase C (PKC) inhibitor, GF109203X (10 µM), completely blocked the effect of PMA but not the LPA‐induced generation of PIP. The present results indicate that LPA can induce PIP formationvia PI‐4‐kinase activation, through processes which are independent of the eicosanoid/TxA2 pathway and are not PKC‐dependent.
The fatty acid composition of human gliomas differs from that found in nonmalignant brain tissue
Authors: Martin Douglas D. , Robbins Michael E. C. , Spector Arthur A. , Wen B.‐Chen , Hussey David H.
Published: March 2007

To compare the fatty acid composition of tumor tissue from glioma patients with that of normal brain tissue, tissue samples were obtained from 13 glioma patients and from 3 nonmalignant patients. Following lipid extraction, total fatty acid composition was measured using gas‐liquid chromatography. Samples were further separated into phospholipids and neutral lipids. Representative samples were then separated into phospholipid classes by thin‐layer chromatography and the fatty acid composition assayed. Levels of the polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA), were significantly reduced (P=0.029) in the glioma samples compared with normal brain samples; mean values were 4.8±2.9% and 9.2±1.0%, respectively. This reduction in glioma DHA content was also observed in terms of phospholipids (4.6±2.1% vs. 9.6±0.8%,P=0.002). The phosphatidylserine and phosphatidylethanolamine phospholipid classes were reduced in the glioma samples. Differences were also noted in the n‐6 PUFA content between glioma and normal brain samples. The glioma content of the n‐6 PUFA linoleic acid was significantly greater (P<0.05) than that observed in the control samples in terms of total lipids. Thus, the fatty acid composition of human gliomas differs from that found in nonmalignant brain tissue.
Ultrasound‐assisted oxidative cleavage of acetylenic and ethylenic bonds in unsaturated fatty esters with potassium permanganate
Authors: Lie Ken Jie Marcel S. F. , Kalluri Prabhavathi
Published: March 2007

The effect of ultrasound on the oxidation of unsaturated fatty esters was investigated. Unsaturated fatty esters containing acetylenic or olefinic bonds or both were oxidatively cleaved with KMnO4 in aqueous acetic acid (AcOH/H2O, 1:1, vol/vol for olefinic fatty esters and AcOH/H2O, 9:1, vol/vol for acetylenic fatty esters) to yield the corresponding carboxylic acid moieties in quantitative yields, when the reactions were conducted under ultrasound (20 kHz, 53 W/cm2, 8–15 min). The methyl ester derivatives of the carboxylic acid moieties formed were identified by gas‐liquid chromatographic analysis. The procedure constitutes a facile method for the determination of the position of the unsaturated center (olefinic or acetylenic) in an unsaturated fatty ester substrate, especially where the unsaturated system consists of an acetylenic bond.
Availability of arachidonic acid in major phospholipids of mucosa and the stomach wall of rats
Authors: Olafsson Sigurdur Oli , Gudbjarnason Sigmundur
Published: March 2007

The purpose of this study was to examine the availability of arachidonic acid in phosphatdidylcholine (PC) and phosphatidylethanolamine (PE) of mucosa and the stomach wall of adult male Wistar rats fed a standard diet. There were significant differences in the fatty acid composition of PC and PE between various parts of the stomach. The mucosa had the lowest level of arachidonic acid (20:4n‐6) in PC, followed by the corresponding stomach wall or glandular part, whereas the forestomach or the upper part had the highest level of 20:4n‐6. The level of 20:4n‐6 in PE was identical in gastric mucosa and the stomach wall of both the lower and upper parts. The levels of 18:1n‐9 and 18:2n‐6 were significantly higher in both PC and PE of mucosa than in the stomach wall. The levels of 16:0 and 18:0 in PC were lower in mucosa than in either forestomach or the glandular part. In mucosal PE, the levels of 18:0 and 22:6n‐3 were lower than in forestomach and glandular part. The glandular part had significantly higher level of 16:0 and lower level of 20:4n‐6 in PC compared to the forestomach. Conclusions: The arachidonic acid level of PC was significantly different in various parts of the rat stomach, with the lowest level in mucosa, whereas the level of 20:4n‐6 in PE was identical in mucosa and stomach wall. These phospholipids had higher levels of saturated fatty acids in the stomach wall than in gastric mucosa.
Viscosity of potassium soap‐potassium silicate mixtures
Authors: Spencer Robert W.
Published: March 2007

Viscosity measurements at 20°C. have been made on mixtures of three potassium soaps with four potassium silicates and potassium chloride in the range of 0 to 100 poises. It was found that the additives have a considerable effect on the viscosity of the potassium linseed oil and the soya bean oil soap solutions, but almost no effect on the viscosities of potassium coconut oil soap solutions in the concentration ranges studied. The alkaline silicates caused greater increases in viscosities than the siliceous silicates. Soap‐KC1 mixtures have viscosities of the same order of magnitude as equivalent soap‐silicate mixtures in this viscosity range.
Surface tension determinations of some saturated fat acid methyl esters
Authors: Nevin C. S. , Althouse P. M. , Triebold H. O.
Published: March 2007

Methyl esters of saturated naturally occurring fat acids from C6 through C18 were prepared and purified by fractional distillation. Refractive indices were used as a measure of their purity. A micro surface tension apparatus was constructed to comply with a modified capillary rise method devised by Ferguson. The surface tensions of water and of benzene were determined at several temperatures. The results obtained compared quite favorably with the values listed in the International Critical Tables. The surface tensions of the methyl esters were determined at 40°C., 60°C., and 80°C. with an accuracy of ±0.15 dynes/cm. Similar to other homologous series the surface tensions of the fat acid methyl esters decrease with increasing temperature, apparently in a linear manner. As the molecular weight of the methyl ester series increases, the surface tension also increases. Close correlation is shown for the methyl esters between the calculated parachors based upon Gibling's system of values and the experimental parachors.
Evaluation of safflowerseed oil in edible fat products
Authors: Soltoft P. , Dollear F. G.
Published: March 2007

Four varieties of safflowerseed grown in Nebraska and Colorado were examined with respect to the composition of the seed, hulls, extracted meal, and oil.

The oil from one variety (Nebraska 852) was (A) refined, bleached, and deodorized; and (B) refined, bleached, hydrogenated, and deodorized. The liquid oil and the hardened fat were analyzed with respect to their fatty acid compositions and their stabilities to rancidity and flavor reversion were determined.

All of the results indicate that safflowerseed oil is not as suitable for edible purposes as other domestically produced edible oils.
Solidification point curves of binary acid mixtures. VII. Undecanoic to pentacosanoic acids
Authors: Schuette H. A. , Christenson R. M. , Stefansson Unnsteinn H. , Fisher Sallie A. , Vogel H. A. , Walker Joseph
Published: March 2007

The clearly defined inflections which characterize the solidification‐point diagrams of binary mixtures of the adjacent, straight‐chain acids of even number carbon atom content in the C8 to C16 area of the homologous series in question are not evident when an “odd” acid enters the picture. Pertinent diagrams for the adjacent odd‐odd acids, C11 to C25, have been constructed.

Although these diagrams have probably no known analytical application at the present, they have a potential one in the indirect determination and characterization of the higher alcohols oxidized to the corresponding acids.
A comparative analysis of some Late Carboniferous basins of Variscan Europe
Authors: OPLUšTIL STANISLAV , CLEAL CHRISTOPHER J.
Published: March 2007

Vegetation diversity and pattern changes, and their relation to tectono-sedimentary histories are compared between selected Euramerican Late Palaeozoic coalfields, to understand better the controls on the dynamics of the Pennsylvanian terrestrial ecosystems and to demonstrate the problems with comparing data from various basins. The analysis is based on data from the following basins of different geotectonic and palaeogeographical positions: the cratonic Pennines Basin, the foreland South Wales and Upper Silesia basins, and the fault-related Intra Sudetic and Central and Western Bohemia basins. The analysis indicates that complex factors are responsible for changes in plant diversity and vegetation patterns. These are related to climate, tectonics, preservation potential, sampling biases and the current state of revision of the flora in each basin. Plant diversity patterns in the basins differ because of local controls and/or the character and detail of the available data. Maximum diversity varies among the basins within the Langsettian and Duckmantian substages. Two apparent step-like drops in diversity were detected within coal-bearing strata of most basins: at the Duckmantian/Bolsovian boundary and at the Bolsovian/Asturian boundary. Further and more prominent falls are related to transitions from coal-bearing to non-coal-bearing (mostly red bed) strata or vice versa during Stephanian times. Interpretation of climatic signals recorded in the sedimentary successions indicates that Westphalian and middle Stephanian times were wet intervals, whereas early and late Stephanian times were drier.
Object detection and mapping for service robot tasks
Authors: Ekvall Staffan , Kragic Danica , Jensfelt Patric
Published: March 2007

The problem studied in this paper is a mobile robot that autonomously navigates in a domestic environment, builds a map as it moves along and localizes its position in it. In addition, the robot detects predefined objects, estimates their position in the environment and integrates this with the localization module to automatically put the objects in the generated map. Thus, we demonstrate one of the possible strategies for the integration of spatial and semantic knowledge in a service robot scenario where a simultaneous localization and mapping (SLAM) and object detection recognition system work in synergy to provide a richer representation of the environment than it would be possible with either of the methods alone. Most SLAM systems build maps that are only used for localizing the robot. Such maps are typically based on grids or different types of features such as point and lines. The novelty is the augmentation of this process with an object-recognition system that detects objects in the environment and puts them in the map generated by the SLAM system. The metric map is also split into topological entities corresponding to rooms. In this way, the user can command the robot to retrieve a certain object from a certain room. We present the results of map building and an extensive evaluation of the object detection algorithm performed in an indoor setting.
Setpoint regulation of continuum robots using a fixed camera
Authors: Chitrakaran V. K. , Behal A. , Dawson D. M. , Walker I. D.
Published: March 2007

In this paper, we investigate the problem of measuring the shape of a continuum robot manipulator using visual information from a fixed camera. Specifically, we capture the motion of a set of fictitious planes, each formed by four or more feature points, defined at various strategic locations along the body of the robot. Then, utilizing expressions for the robot forward kinematics as well as the decomposition of a homography relating a reference image of the robot to the actual robot image, we obtain the three-dimensional shape information continuously. We then use this information to demonstrate the development of a kinematic controller to regulate the manipulator end-effector to a constant desired position and orientation.
Olive oil and haemostasis: a review on its healthy effects
Authors: Pérez-Jiménez Francisco , Lista Javier Delgado , Pérez-Martínez Pablo , López-Segura Fernando , Fuentes Francisco , Cortés Begoña , Lozano Aquiles , López-Miranda José
Published: March 2007

Interest in the Mediterranean diet (MD) has grown worldwide. Despite the high complexity of its nutrients composition, olive oil emerges as its principal food, since it provides the higher percentage of energy and a lot of bioactive compounds.

Objective

In this review, we will discuss the benefits of diets enriched in virgin olive oil, whose effects are probably due not only to its oleic acid content but also to its other potentially health-promoting components.

Methods

Traditionally, the benefits of MD were linked to its effect on lipoprotein metabolism, but today we realise that there exists a whole sheaf of other benefits, including the components of haemostasis: platelet function, thrombogenesis and fibrinolysis.

Results

A diet enriched in virgin olive oil can reduce the sensitivity of platelets to aggregation, decreasing von Willebrand and thromboxane B2 plasma levels. Moreover, a particular interest has aroused about its capacity to decrease fasting factor VII plasma levels and to avoid or modulate its postprandial activation. In addition, tissue factor expression in mononuclear cells could be reduced with the chronic intake of virgin olive oil, and finally, studies performed in different experimental situation have shown that it could also increase fibrinolytic activity, reducing plasma concentration of plasma activator inhibitor type-1 (PAI-1).

Conclusion

The MD is an alimentary model with a high content of monounsaturated fats that is capable of inducing a wide range of biological effects on the cardiovascular system. The application of modern focuses of study will dilucidate in the future the biological and clinical interest of these findings.
Mediterranean diet and depression
Authors: Sánchez-Villegas A , Henríquez P , Bes-Rastrollo M , Doreste J
Published: March 2007

Objective

The adherence to a Mediterranean Dietary Pattern ensures an adequate intake of B vitamins and w-3 fatty acids. A protective role on depression has been suggested for both nutrients.

Design

Cross-sectional analysis from the SUN (Seguimiento Universidad de Navarra) prospective cohort study. Data from 9670 participants (4211 men and 5459 women) were analised. Logistic regression analyses were fitted to assess the association between B-vitamins and w-3 fatty acids intake (quintiles) and the prevalence of depression.

Results

Folate intake was inversely associated with depression prevalence among men, especially smokers. Among women, B12 vitamin intake was inversely associated with depression, especially among smokers and physically active women. No significant associations were observed for w-3 fatty acids intake.

Conclusions

The adherence to a Mediterranean Dietary Pattern ensures an adequate intake of fruits, nuts, vegetables, cereals, legumes or fish, important sources of nutrients linked to depression prevention.
Maximum number of habitable planets at the time of Earth’s origin: new hints for panspermia and the mediocrity principle
Authors: Franck Siegfried , von Bloh Werner , Bounama Christine
Published: March 2007

In this paper we estimate the number of habitable planets in our Galaxy over cosmological time scales. This number can be derived from the planet formation rate (PFR) of Earth-like planets and the convolution of this value with the probability of being habitable. The PFR is calculated from the star formation rate (SFR) with the help of a so-called Goldilocks problem. The probability that an Earth-like planet is in the habitable zone (HZ) is estimated with the help of our Earth system model. In order to calculate the HZ an integrated system approach is used, taking into account a variety of climatological, biogeochemical, and geodynamical processes. Habitability is linked to the photosynthetic activity on the planetary surface. We find that habitability strongly depends on the age of the stellar system and the characteristics of a virtual Earth-like planet. There was a maximum number of habitable planets around the time of the Earth’s origin and interstellar panspermia was most probable at that time. Furthermore, we discuss our results in the framework of the so-called principle of mediocrity.
Was ist Motilität?
Authors: Beglinger
Published: March 2007

Die Verdauungsfunktionen werden durch ein komplexes Steuerungssystem kontrolliert mit der Zielsetzung, Nahrung zu verdauen, aufzuspalten und aufzunehmen; gleichzeitig sollen alle nicht benötigten Substanzen oder unverdauliche Nahrungsbestandteile ausgeschieden werden. Störungen in der Funktion dieses Regelsystems beruht häufig auf fehlerhaften Interaktionen und kann zu Dysfunktionen des Transits mit entsprechenden Symptomen führen.
Gastrointestinale Motilität – Physiologie und Messmethoden
Authors: Degen
Published: March 2007

Die Entwicklung moderner Untersuchungsverfahren erlaubte es erst die physiologischen Eigenschaften der gastrointestinalen Motilität zu verstehen. Entsprechend seinen physiologischen Funktionen lässt sich der Magen in einen proximalen und distalen Anteil unterteilen, die ganz unterschiedliche Aufgaben erfüllen. Charakteristisch für den Dünndarm ist im Nüchternzustand eine zyklische periodische Peristaltik (sog. Interdigestive Migrating Motor Complexes), die bis zum Ileum propagiert wird und postprandial vorübergehend durch ein unregelmäßiges Kontraktionsmuster abgelöst wird. Die Kolonmotilität ist durch tonische und phasische Kontraktionen charakterisiert. In unregelmäßigen Abständen lassen sich hier über den Tag verteilt vereinzelte sogenannte Massenbewegungen beobachten, denen ausgeprägte Kontraktionswellen zugrunde liegen (= High Amplitude Propagated Contractions). Zur Messung der gastrointestinalen Motilität hat sich im klinischen Alltag die Manometrie etabliert. Hier werden mit technisch unterschiedlichen Drucksensoren die Kontraktionen sowohl im Nüchternzustand als auch postprandial untersucht. Der Transitprozess des gesamten Gastrointestinaltrakts als Produkt der eigentlichen Motilität wird am genauesten und detailliertesten szintigraphisch untersucht. Als einfache und trotzdem zuverlässige Methode zur kursorischen Messung der Kolonpassagezeit bietet sich vor allem auch für die Praxistätigkeit die röntgendichte Marker Methode an.
Funktionelle Dyspepsie
Authors: Gschossmann  , Essig
Published: March 2007

Auf den Oberbauch fokusierte chronisch-rezidivierende Abdominalbeschwerden ohne Erklärung durch strukturelle oder biochemische Abnormaliäten werden unter dem Begriff der funktionellen Dyspepsie zusammengefasst. Zwar konnten in den letzten Jahren signfikante Fortschritte hinsichtlich dem pathophysiologischen Verständnis dieses Krankheitsbildes erzielt werden, doch ist vor allem die für die betroffenen Patienten entscheidende Frage nach Therapieoptionen noch immer nur partiell und in Ansätzen geklärt. Diese sind aktuell vor allem symptomorientiert und nur eingeschränkt wissenschafltlich belegt. Es besteht jedoch berechtigter Grund zur Hoffnung, dass durch neue Therapieansätze und vor allem auch interdisziplinäres Vorgehen ein Lösungsansatz für diese unbefriedigende Situation resultieren wird.
Das Reizdarmsyndrom
Authors: Truninger
Published: March 2007

Das Reizdarmsyndrom (RDS) gehört zu den häufigsten funktionellen Magen-Darm-Erkrankungen und präsentiert sich mit abdominalen Schmerzen und einer Änderung der Stuhlgewohnheit. Extraintestinale Beschwerden wie Kopfschmerzen, aber auch assoziierte psychische Störungen wie Depression und Angstzustände finden sich bei RDS-Patienten gehäuft. Die wichtigsten pathogenetischen Elemente sind, eine genetische Prädisposition, Motilitätsstörungen, viszerale Hypersensitivität, immunologische Dysfunktionen und eine pathologische Hirn-Darm-Interaktion. Die Grundlage der Diagnose bilden die neuen, Symptom-basierten Rom-III-Kriterien. Die Diagnostik benötigt eine genaue Anamneseerhebung, die körperliche Untersuchung sowie wenige Laboruntersuchungen und lehnt sich im weiteren an die erhobenen Befunde, das Patientenalter, Dauer und Schweregrad der Beschwerden, das Vorhandensein atypischer Symptome, psychosoziale Faktoren sowie die Familienanamnese für Tumore an. Der therapeutische Ansatz erfolgt individuell und richtet sich nach dem RDS-Schweregrad, der vorherrschenden Symptomatik und assoziierten Störungen. Die Behandlungsmöglichkeiten umfassen Modifikationen im Lebensstil, Pharmakotherapie entsprechend der prädominanten Symptomatik und verschiedene Formen von Verhaltenstherapien.
Do sulfate and nitrate coatings on mineral dust have important effects on radiative properties and climate modeling?
Authors: Bauer S. E. , Mishchenko M. I. , Lacis A. A. , Zhang S. , Perlwitz J. , Metzger S. M.
Published: March 2007

Coating of mineral dust particles by air pollutants leads to core‐mantle particles. These composite aerosols could interact differently with atmospheric radiation than the uncoated dust. In our simplified radiative calculations we assumed that a spherical dust core is covered uniformly by a liquid refractive material, such as sulfate or nitrate. Theoretical calculations of optical properties of such particles show that the single‐scattering albedo and the asymmetry parameter of core‐mantle aerosols only differ significantly from uncoated dust if coating layers exceed 20% of the radius of the dust core. Global simulations of sulfate/nitrate‐coated dust particles show that the thickness of the shell can be expected to range from 0 to 20% of the radius of the dust core. The result of this work is that mineral dust particles can be treated as external mixture within radiative calculations but the coating processes lead to changed loads in sulfate, nitrate, and mineral dust aerosol loads and therefore change their impact on Earth radiation. The combined anthropogenic forcing of dust, nitrate, and sulfate aerosols is −0.1 W/m2; however, excluding heterogeneous interactions leads to a 3 times larger negative forcing.
Expansion of the Hadley cell under global warming
Authors: Lu Jian , Vecchi Gabriel A. , Reichler Thomas
Published: March 2007

A consistent weakening and poleward expansion of the Hadley circulation is diagnosed in the climate change simulations of the IPCC AR4 project. Associated with this widening is a poleward expansion of the subtropical dry zone. Simple scaling analysis supports the notion that the poleward extent of the Hadley cell is set by the location where the thermally driven jet first becomes baroclinically unstable. The expansion of the Hadley cell is caused by an increase in the subtropical static stability, which pushes poleward the baroclinic instability zone and hence the outer boundary of the Hadley cell.
Climate variability effects on spatial soil moisture dynamics
Authors: Teuling Adriaan J. , Hupet François , Uijlenhoet Remko , Troch Peter A.
Published: March 2007

We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain‐la‐Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics are simulated with a comprehensive model for the period 1989–2003. The results show that climate variability induces non‐uniqueness and two distinct hysteresis modes in the yearly relation between the spatial mean soil moisture and its variability. We demonstrate that the direction of hysteresis is related to a yearly climate index that does not require soil moisture observations.
Characterizing the Galicia Bank‐Southern Iberia Abyssal Plain rifted margin segment boundary using multichannel seismic and ocean bottom seismometer data
Authors: Clark Stephen A. , Sawyer Dale S. , Austin James A. , Christeson Gail L. , Nakamura Yosio
Published: March 2007

We present multichannel seismic reflection and ocean bottom seismometer reflection/refraction data from ISE‐9, a margin‐parallel, north–south oriented profile ∼200 km west of the Portuguese coast. ISE‐9 images the boundary between two distinct segments of the Iberia nonvolcanic rifted margin: Galicia Bank (GB) and the Southern Iberia Abyssal Plain (SIAP). The bathymetric contrast between GB (2 km depth) and SIAP (4–5 km depth) spans only 25 km. The crustal thickness transition, however, spans 137 km, from 13–18 km thick beneath GB to <2 km thick beneath SIAP. We define this crustal thickness transition as the segment boundary. Crustal structure along the segment boundary, tilted blocks bounded by normal faults, is surprisingly similar to crustal structure observed along orthogonal, east–west profiles of the Iberia margin. The apparent north–south extension is similar in magnitude to previously calculated east–west extension, implying an overall northeast–southwest extension. However, paleoreconstructions and rift basin orientations constrain lithospheric extension to a nearly east–west direction. We speculate that north–south extension is limited to the crust and is caused by large‐scale mass wasting sometime between the Tithonian and Valanginian. This rotational slump spans the 137‐km‐wide modern segment boundary, emplacing GB continental crust directly onto exhumed, serpentinized mantle of SIAP. Palinspastic reconstruction restores the southern edge of the blocks to coincide within <10 km of a steep Moho transition and a near‐vertical fault which extends through the slump and offsets Moho. We interpret this location as the preslump segment boundary that accommodated transform motion between the two rifted margin segments.
Eocene paleomagnetic pole for South America: Northward continental motion in the Cenozoic, opening of Drake Passage and Caribbean convergence
Authors: Somoza Rubén
Published: March 2007

A paleomagnetic study of Eocene volcanic rocks in Patagonia yields high unblocking temperature and high‐coercivity magnetizations. Combining these results with those of a previous study on Patagonian Eocene basalts yields a high‐precision, high‐quality pole located at latitude 81°S, longitude 337.4°E, A95 = 5.7°. Critically, this paleopole is indistinguishable from that of the Late Cretaceous (circa 85–65 Ma) pole position of South America, indicating that the plate was essentially motionless with respect to the spin axis for a period of ∼45 m.y. The pole position places South America at higher (∼5°) than present‐day latitudes during the Eocene, indicating that northward continental motion toward present‐day latitudes must have been accomplished sometime since the late Eocene. Paleomagnetic and tectonic correlation admits the hypothesis that Cenozoic northward drift was associated with Oligocene‐Miocene extension in the southern continental edge, leading to the opening of the Drake Passage, and it agrees with the timing of foredeep formation and development of fold‐thrust belts in the northern continental edge. This positive correlation between the paleomagnetically predicted drift of a major continent with extension at its trailing edge and convergence at its leading edge during times for which seafloor tectonic fabric and the geological record are particularly well preserved illustrates the utility of paleomagnetism in constraining paleogeographic and tectonic reconstructions for pre‐Cretaceous times.
Simulation and characterization of the Adriatic Sea mesoscale variability
Authors: Cushman‐Roisin Benoit , Korotenko Konstantin A. , Galos Camelia E. , Dietrich David E.
Published: March 2007

This paper presents simulations of the Adriatic Sea using the DieCAST model applied on a 1.2–min grid (about 2–km resolution). The simulations resolve the mesoscale variability because the grid size falls below the first baroclinic deformation radius (about 5–10 km) and DieCAST has very low horizontal dissipation. The model is initialized with seasonally averaged temperature and salinity data and forced with climatological winds and surface buoyancy fluxes (both heat flux and evaporation minus precipitation). River discharges are varied daily according to a perpetual year for every river, and the open‐boundary conditions at Otranto Strait are obtained by nesting in two larger‐scale models. The present simulations demonstrate that the DieCAST model allows mesoscale instabilities to develop at length scales of 5–20 km and over time scales of a few days. The simulated variability exhibits pronounced similarities with the actual mesoscale variability, in terms of location, nature and temporal evolution of the features. Meanders, swirls and eddies are noted along the relatively smooth Italian coast while offshore jets and filaments better describe the mesoscale activity along the more rugged coast of Croatia. In sum, DieCAST is highly suitable for the study of mesoscale variability in the Adriatic Sea. The present simulations also show that the seasonal hydrography of the Adriatic Sea is intrinsically unstable to mesoscale perturbations, and that the mesoscale variability along the Italian coast is the result of baroclinic instability of the Western Adriatic Current. It is shown how the properties of this instability are related to the local bottom topography.
Oxidation of oleic acid at air/liquid interfaces
Authors: Voss Laura F. , Bazerbashi Mohamad F. , Beekman Christopher P. , Hadad Christopher M. , Allen Heather C.
Published: March 2007

Oxidation of oleic acid monolayers by ozone was studied to understand the fate of fat‐coated aerosols from both freshwater and saltwater sources. Oleic acid monolayers at the air/water interface and at the air/sodium chloride solution interface were investigated using surface‐specific, broad‐bandwidth, sum frequency generation spectroscopy. Complementary techniques of infrared reflection adsorption spectroscopy and surface pressure measurements taken during monolayer oxidation confirmed the sum frequency results. Using this nonlinear optical technique coupled with a Langmuir trough, concurrent spectroscopic and thermodynamic data were collected to obtain a molecular picture of the monolayers. No substantial difference was observed between oxidation of monolayers spread on water and on 0.6 M sodium chloride solutions. Results indicate that depending on the size of the aerosol and the extent of oxidation, the subsequent oxidation products may not remain at the surface of these films, but instead be dissolved in the aqueous subphase of the aerosol particle. Results also indicate that oxidation of oleic acid could produce monolayers containing species that have no oxidized acyl chains.
Sprite lightning heard round the world by Schumann resonance methods
Authors: Williams E. R. , Mushtak V. C. , Boldi R. , Dowden R. L. , Kawasaki Z.‐I.
Published: March 2007

Electromagnetic transients have been recorded at the Massachusetts Institute of Technology field station in West Greenwich, Rhode Island, coinciding with sprite‐producing lightning flashes in northern Australia, at a distance of 16.6 Mm. Single‐station Schumann resonance methods have been used to locate the parent lightning flashes and to evaluate their vertical charge moments. The charge moment thresholds for sprite production are consistent with similar measurements with identical methods made at considerably closer range (∼2 Mm). The use of a uniform model for the Earth‐ionosphere waveguide can produce systematic errors in the source‐receiver distance, of the order of 1 Mm. Further analysis of the observations has shown an important role for the day‐night asymmetry of the waveguide in causing the systematic error, by lending appreciable asymmetry to the short and long paths of propagation round the world.
Recurrence plots and Shannon entropy for a dynamical analysis of asynchronisms in noninvasive mechanical ventilation
Authors: Rabarimanantsoa H. , Achour L. , Letellier C. , Cuvelier A. , Muir J.-F.
Published: March 2007

Recurrence plots were introduced to quantify the recurrence properties of chaotic dynamics. Hereafter, the recurrence quantification analysis was introduced to transform graphical interpretations into statistical analysis. In this spirit, a new definition for the Shannon entropy was recently introduced in order to have a measure correlated with the largest Lyapunov exponent. Recurrence plots and this Shannon entropy are thus used for the analysis of the dynamics underlying patient assisted with a mechanical noninvasive ventilation. The quality of the assistance strongly depends on the quality of the interactions between the patient and his ventilator which are crucial for tolerance and acceptability. Recurrence plots provide a global view of these interactions and the Shannon entropy is shown to be a measure of the rate of asynchronisms as well as the breathing rhythm.
The evolution of magnetic tower jets in the laboratory
Authors: Ciardi A. , Lebedev S. V. , Frank A. , Blackman E. G. , Chittenden J. P. , Jennings C. J. , Ampleford D. J. , Bland S. N. , Bott S. C. , Rapley J. , Hall G. N. , Suzuki-Vidal F. A. , Marocchino A. , Lery T. , Stehle C.
Published: March 2007

The evolution of laboratory produced magnetic jets is followed numerically through three-dimensional, nonideal magnetohydrodynamic simulations. The experiments are designed to study the interaction of a purely toroidal field with an extended plasma background medium. The system is observed to evolve into a structure consisting of an approximately cylindrical magnetic cavity with an embedded magnetically confined jet on its axis. The supersonic expansion produces a shell of swept-up shocked plasma that surrounds and partially confines the magnetic tower. Currents initially flow along the walls of the cavity and in the jet but the development of current-driven instabilities leads to the disruption of the jet and a rearrangement of the field and currents. The top of the cavity breaks up, and a well-collimated, radiatively cooled, “clumpy” jet emerges from the system.
Collective temperature anisotropy instabilities in intense charged particle beams
Authors: Startsev Edward A. , Davidson Ronald C. , Qin Hong
Published: March 2007

The classical electrostatic Harris instability and the electromagnetic Weibel instability, both driven by a large temperature anisotropy (T‖b∕T⊥b⪡1) that develops naturally in accelerators, are generalized to the case of a one-component intense charged particle beam with anisotropic temperature, including the important effects of finite transverse geometry and beam space-charge. Such instabilities may lead to an increase in the longitudinal velocity spread, which makes focusing the beam difficult, and may impose a limit on the beam luminosity and the minimum spot size achievable in focusing experiments. This paper describes recent advances in the theory and simulation of collective instabilities in intense charged particle beams caused by large temperature anisotropy. The new simulation tools that have been developed to study these instabilities are also described. Results of the investigations that identify the instability growth rates, levels of saturations, and conditions for quiescent beam propagation are also discussed.
Spatial and spectral evolution of turbulence
Authors: Gürcan Ö. D. , Diamond P. H. , Hahm T. S.
Published: March 2007

Spreading of turbulence as a result of nonlinear mode couplings and the associated spectral energy transfer is studied. A derivation of a simple two-field model is presented using the weak turbulence limit of the two-scale direct interaction approximation. This approach enables the approximate overall effect of nonlinear interactions to be written in the form of Fick’s law and leads to a coupled reaction-diffusion system for turbulence intensity. For this purpose, various classes of triad interactions are examined, and the effects that do not lead to spreading are neglected. It is seen that, within this framework, large scale, radially extended eddies are the most effective structures in promoting spreading of turbulence. Thus, spectral evolution that tends toward such eddies facilitates spatial spreading. Self-consistent evolution of the background profile is also considered, and it is concluded that the profile is essentially slaved to the turbulence in this phase of rapid evolution, as opposed to the case of avalanches, where it is the turbulence intensity that would be slaved to the evolving profile. The characteristic quantity describing the evolving background profile is found to be the mean “potential vorticity” (PV). It is shown that the two-field model with self-consistent mean PV evolution can be reduced to a single Fisher-like turbulence intensity transport equation. In addition to the usual nonlinear diffusion term, this equation also contains a “pinch” of turbulence intensity. It is also noted that internal energy spreads faster than kinetic energy because of the respective spectral tendencies of these two quantities.
Sawtooth oscillations in shaped plasmas
Authors: Lazarus E. A. , Luce T. C. , Austin M. E. , Brennan D. P. , Burrell K. H. , Chu M. S. , Ferron J. R. , Hyatt A. W. , Jayakumar R. J. , Lao L. L. , Lohr J. , Makowski M. A. , Osborne T. H. , Petty C. C. , Politzer P. A. , Prater R. , Rhodes T. L. , Scoville J. T. , Solomon W. M. , Strait E. J. , Turnbull A. D. , Waelbroeck F. L. , Zhang C.
Published: March 2007

The role of interchange and internal kink modes in the sawtooth oscillations is explored by comparing bean- and oval-shaped plasmas. The n=1 instability that results in the collapse of the sawtooth has been identified as a quasi-interchange in the oval cases and the internal kink in the bean shape. The ion and electron temperature profiles are followed in detail through the sawtooth ramp. It is found that electron energy transport rates are very high in the oval and quite low in the bean shape. Ion energy confinement in the oval is excellent and the sawtooth amplitude (δT∕T) in the ion temperature is much larger than that of the electrons. The sawtooth amplitudes for ions and electrons are comparable in the bean shape. The measured q profiles in the bean and oval shapes are found to be consistent with neoclassical current diffusion of the toroidal current, and the observed differences in q largely result from the severe differences in electron energy transport. For both shapes the collapse flattens the q profile and after the collapse return to q0≳1. Recent results on intermediate shapes are reported. These shapes show that the electron energy transport improves gradually as the plasma triangularity is increased.
Ultrafast dynamics of neutral, ultracold plasmas
Authors: Murillo Michael S.
Published: March 2007

The ultrafast dynamics of a neutral, ultracold plasma following an energy landscape shift is studied theoretically and with simulation. To lowest order in time, the inertial dynamics on the new landscape can be characterized by the initial-state plasma microfield, which, for the randomly ordered case of an ultracold neutral plasma, is dominated by nearest-neighbor interactions. Formation of the pair correlation function arises after ballistic overshoot, which leads to oscillations in the effective temperature. Connections are made to similar properties of clusters, photoisomerization of molecules, and nonthermal melting in solids.
Dielectric surface flashover at atmospheric conditions under high-power microwave excitation
Authors: Neuber Andreas A. , Krile John T. , Edmiston Greg F. , Krompholz Hermann G.
Published: March 2007

Due to recent advances in the peak output power densities and pulse widths of high-power microwave (HPM) devices, the ability to radiate this power into the atmosphere is limited by surface plasma formation at the vacuum-air interface. Very little is known about this window flashover under HPM excitation at “air” side pressures from atmospheric down to approximately 90Torr, and this paper reports one such study at 2.85GHz and MW∕cm2 pulsed power densities. Due to the high (∼600GHz at standard temperature and pressure) elastic collision frequencies of the electrons with the neutral gas molecules and added energy-loss channels through molecule excitation, proven concepts of vacuum flashover, such as multipactoring electrons, have to be abandoned. The observed flashover field is roughly a factor 3 higher in SF6 compared to air, which is consistent with unipolar volume breakdown data. Quantitative comparisons of HPM flashover data with results from a recently developed computer code are given.
High-intensity laser interactions with mass-limited solid targets and implications for fast-ignition experiments on OMEGA EP
Authors: Myatt J. , Theobald W. , Delettrez J. A. , Stoeckl C. , Storm M. , Sangster T. C. , Maximov A. V. , Short R. W.
Published: March 2007

The modeling of petawatt laser-generated hot electrons in mass-limited solid-foil-target interactions at “relativistic” laser intensities is presented using copper targets and parameters motivated by recent experiments at the Rutherford Appleton Laboratory Petawatt and 100-TW facilities [Theobald et al., Phys. Plasmas 13, 043102 (2006)]. Electron refluxing allows a unique determination of the laser-electron conversion efficiency and a test with simulations. Good agreement between experiments and simulations is found for conversion efficiencies of 10%.
Observation of localized charge transport in isolated microscopic mats of single-wall carbon nanotubes
Authors: Glover Brian B. , Perry W. Lee
Published: March 2007

We have formulated a composite consisting of a low dielectric permittivity, low loss granular organic crystal, and 0.1% single-walled carbon nanotubes (SWNTs). The composite morphology was electrically isolated “mats” of SWNTs distributed on the surface of individual crystals having a typical particle size of 20μm. The real part of the composite permittivity (relative) was not significantly different from that of the matrix material (∼2.0), while the dielectric loss increased from 0.0035 to 0.3 at 2.45GHz. We used Maxwell-Garnett mixing theory, which accounts for interfacial polarization, to calculate complex permittivity and conductivity of the SWNT mats. The results indicated weak electrical contact between SWNTs within the mats, implying that localized electron transport was the primary dielectric loss mechanism.