bluuebunny/crossref_metadata_2025 huggingface dataset:
Misperceptions, inactivity and maternal factors may drive obesity
among Barbadian adolescents
Authors: Gaskin Pamela S , Broome Hedy , Alert Colin , Fraser Henry
Published: June 2007

Objectives

To describe (1) the prevalence of overweight and obesity and their
association with physical activity; (2) the effect of different cut-off
points for body mass index (BMI) on weight status categorisation; and (3)
associations of weight status with perceptions of body size, health and diet
quality.

Design

A cross-sectional study.

Setting

Secondary schools in Barbados.

Subjects

A cohort of 400 schoolchildren, 11–16 years old, selected to study
physical education practices.

Results

Prevalence of overweight (15% boys; 17% girls) and obesity (7% boys; 12%
girls) was high. Maternal obesity, as defined by the International Obesity
Task Force (IOTF) BMI cut-off points, predicted weight status such that
reporting an obese mother increased the odds of being overweight by 5.25
(95% confidence interval: 2.44, 11.31). Physical activity was inversely
associated with weight status; however levels were low. Recreational
physical activity was not associated with weight status in either category.
Overweight subjects tended to misclassify themselves as normal weight and
those who misclassified perceived themselves to be of similar health status
to normal-weight subjects. The National Center for Health Statistics and
IOTF BMI cut-off points produced different estimates of overweight and
obesity.

Conclusions

Our findings suggest that inadequate physical activity and ignorance related
to food and appropriate body size are promoting high levels of adiposity
with a strong contribution from maternal obesity, which may be explained by
perinatal and other intergenerational effects acting on both sexes.
Prevalence studies and local proxy tools for adiposity assessment are
needed.
Monetary costs of dietary energy reported by young Japanese women: association with food and nutrient intake and body mass index
Authors: Murakami Kentaro , Sasaki Satoshi , Okubo Hitomi , Takahashi Yoshiko , Hosoi Yoko , Itabashi Mami
Published: June 2007

Objective

Little is known about the relationship of monetary diet costs to dietary intake and obesity, particularly in non-Western populations. This study examined monetary cost of dietary energy in relation to diet quality and body mass index (BMI) among young Japanese women.

Design

Dietary intake was assessed by a validated, self-administered, diet history questionnaire. Diet costs were estimated using retail food prices. Monetary cost of dietary energy (Japanese yen 1000 kcal−1) was then calculated. BMI was computed from self-reported body weight and height.

Subjects

A total of 3931 female Japanese dietetic students aged 18–20 years.

Results

Monetary cost of dietary energy was positively associated with intakes of fruits, vegetables, fish and shellfish, and pulses; however, higher monetary cost of dietary energy was also associated with higher consumption of fat and oil, meat and energy-containing beverages, and lower consumption of cereals (rice, bread and noodles) (all P for trend <0.01). At the nutrient level, monetary cost of dietary energy was positively associated with intakes of dietary fibre and key vitamins and minerals, but also associated positively with intakes of fat, saturated fatty acids, cholesterol and sodium, and negatively with carbohydrate intake (all P for trend <0.0001). After adjustment for possible confounders, monetary cost of dietary energy was quite weakly but significantly negatively associated with BMI (P for trend = 0.0197).

Conclusions

Increasing monetary cost of dietary energy was associated with both favourable and unfavourable dietary intake patterns and a quite small decrease in BMI in young Japanese women.
Debussy’s Arabesque and Ravel’s Daphnis et Chloé (1912)
Authors: BHOGAL GURMINDER KAUR
Published: June 2007

Just as arabesque carries a range of visual and literary associations, this ornament assumes a diverse presence in music scholarship, where it characterizes a wide repertoire and assortment of techniques. Despite its conceptual breadth, this essay shows that arabesque upheld a specific musical identity for Debussy and Ravel. This is reflected in their simulation of art nouveau’s intricate and fluid designs through melodic gestures that emphasize irregular rhythms and dissonant metres. Also in keeping with art nouveau is the tendency of these composers to privilege musical arabesque’s structural appearance and expressive capacity. These observations are explored with reference to Ravel’s Daphnis et Chloé, a ballet that critics admired for its arabesque qualities. An analysis of four dances will reveal how the distinct rhythmic and metric profiles of arabesque melodies portray characters and their narratives. In challenging preconceptions of ornament as marginal and meaningless, this essay shows how arabesque became endowed with structural and expressive significance at the début du siècle.
Adam Smith and the Dark Nightingale: On Twentieth-Century Sentimentalism
Authors: STOKES MARTIN
Published: June 2007

This article reconsiders sentimentalism in the light of the writings of Adam Smith and the career of Abd al-Halim Hafiz, Egypt’s ‘Dark Nightingale’ and film-star crooner of the 1950s and 60s. It explores competing representations of emotionality, the limits of enchantment, and the contemporary politics of nostalgia and melodrama in Egyptian public culture. Eighteenth-century sentimental theory provides a critical and productive angle on twentieth-century popular musical culture, angles that this paper explores by imagining Adam Smith watching Abd al-Halim Hafiz’s first film, Lahn al-Wafā‘ (1955).
Trying To Speak: Between Politics and Aesthetics, Darmstadt 1970–1972
Authors: IDDON MARTIN
Published: June 2007

In the historiography of the Darmstadt Ferienkurse, the 1970s, when they are examined at all, are generally regarded as a period of stagnation, between the fervour of serial activity in the 1950s and the resurgence of the courses in the 1980s under the banner of various inflections of New Complexity. Yet, in a period of political upheaval after 1968, dissent was felt at Darmstadt too, and protests in 1970 and 1972 saw the institution at its most politically volatile. These protest movements caused the courses’ director, Ernst Thomas, to institute wide-scale changes in their structure and content. Key roles in these protests were taken by journalists: indeed, clear parallels can be drawn between the seemingly egalitarian calls from journalists for Mitbestimmung (co-determination) at Darmstadt and the similar demands being made by their trade unions in the West German federation. Thomas’s failure to deal with journalistic pressure and his heavy-handed treatment of individual protesters (notably Reinhard Oehlschlägel) meant that, shrewd and durable though his reinvention of the courses was, it would be only in 1982, with the accession of a new director, that the press would begin to speak positively about the Darmstadt courses once more. A close reading of these two protests shows the sometime ‘citadel of the avant-garde’ at a distinctly precarious moment in its history. At the time, some felt that such protests could lead to the demise of the courses, and it was far from clear whether Thomas’s reforms would be successful. But, even within this period of uncertainty, the Darmstadt Ferienkurse were anything but stagnant.
On the effects of the electromagnetic source modeling in the iterative multiscaling method
Authors: Franceschini Davide , Donelli Massimo , Massa Andrea
Published: June 2007

The validation against experimental data is a fundamental step in the assessment of the effectiveness of a microwave imaging algorithm. It is aimed at pointing out the limitations of the numerical procedure for a successive application in a real environment. Towards this end, this paper evaluates the reconstruction capabilities of the Iterative Multiscaling Approach (IMSA) when dealing with experimental data by considering different numerical models of the illuminating setup. In fact, since the incident electromagnetic field is usually collected in a limited set of measurement points and inversion methods based on the use of the “state” equation require the knowledge of the radiated field in a finer grid of positions, an effective numerical procedure for the synthesis of the electromagnetic source is generally needed. Consequently, the performances of the inversion process may be strongly affected by the numerical model and, in such a case, a great care should be devoted to this key issue to guarantee suitable and reliable reconstructions.
Antarctic atmospheric temperature trend patterns from satellite observations
Authors: Johanson Celeste M. , Fu Qiang
Published: June 2007

Tropospheric temperatures in the Antarctic are retrieved by linearly combining satellite‐borne Microwave Sounding Unit (MSU) channels 2 and 4 observations. We show good agreement between satellite‐inferred temperature trends and radiosonde observations. It is illustrated that the Antarctic troposphere has cooled in the summer and fall seasons since 1979, in agreement with Thompson and Solomon (2002). It is shown that significant tropospheric warming prevails during Antarctic winters and springs, but we also find significant winter cooling over half of East Antarctica. We find the largest winter tropospheric warming of about 0.6 K/decade for 1979–2005 between 120°W and 180°W. Homogeneous winter tropospheric warming over Antarctica from the ERA‐40 reanalysis is not supported by the MSU observations. While MSU stratospheric temperatures exhibit the expected large cooling during the spring and summer seasons, we also find large stratospheric warming over half the southern hemisphere high latitudes in the winter and spring seasons.
Imaging coherent scatter radar, incoherent scatter radar, and optical observations of quasiperiodic structures associated with sporadic E layers
Authors: Larsen M. F. , Hysell D. L. , Zhou Q. H. , Smith S. M. , Friedman J. , Bishop R. L.
Published: June 2007

During June and July 2002, a 30‐MHz imaging coherent scatter radar was installed and operated on the island of St. Croix, to view the E region ionosphere above Arecibo, Puerto Rico. During the observing period, 10 events with discernible quasiperiodic echo structure were observed with the coherent scatter radar. In six of those events, simultaneous measurements were made with the Arecibo 430‐MHz incoherent scatter radar. The imaging coherent scatter radar allows us to locate and track the echo structures within the volume illuminated by the transmitter, which shows structures that are generally aligned along wavefronts. A slight preference for motion of the structures toward the southwest is evident throughout the period, but the propagation directions and speeds vary greatly. The incoherent scatter radar measurements show a close correspondence between the occurrence of the coherent echoes and the location of the enhanced electron density structures. In particular, the coherent echoes occur when the electron density layers show uplifts.
Retrieval of phytoplankton biomass from simultaneous inversion of reflectance, the diffuse attenuation coefficient, and Sun‐induced fluorescence in coastal waters
Authors: Huot Yannick , Brown Catherine A. , Cullen John J.
Published: June 2007

A model has been developed to retrieve phytoplankton absorption, a proxy for phytoplankton biomass, from observations of reflectance (R) and the diffuse attenuation coefficient (Kd) collected by moored radiometers in coastal waters, where high concentrations of chromophoric dissolved organic matter (CDOM) confound conventional ocean color algorithms. The inversion uses simultaneously two forward models: (1) a look‐up table (LUT) that accounts for instrument geometry and the effect of the solar angle on both R and Kd and (2) an analytical function describing the effects of Sun‐induced fluorescence (SIF) of chlorophyll on R. Estimates of phytoplankton biomass (mostly from SIF), the absorption by colored matter, and the particulate backscattering coefficients (mostly from the LUT) are obtained by optimizing the amplitude and shape of the absorption and backscattering coefficients in the forward model to best match the observations. An equation describing the quantum yield of fluorescence (photons fluoresced/photons absorbed) as a function of incident irradiance constrains the model and allows estimates of phytoplankton absorption. Innovations include: the utilization of both R and Kd, providing good separation of the effects of backscattering from absorption; avoidance of reflectance bands between 400 and 600 nm, thereby avoiding interference from bottom reflection and CDOM fluorescence; utilization of the full emission band of SIF; and accounting for the irradiance‐dependence of its quantum yield. The model effectively retrieved chlorophyll concentration from an independent data set — r = 0.76, n = 93, with a mean absolute percent error (MAPE) of 24%; this is better than a modern ocean color algorithm (OC4V4) on its validation data set, when restricted to the same range of chlorophyll (r = 0.67, n = 384, MAPE = 51%).
Effect of wave‐topography interactions on the formation of sand ridges on the shelf
Authors: Vis‐Star N. C. , de Swart H. E. , Calvete D.
Published: June 2007

The role of wave‐topography interactions in the formation of sand ridges on microtidal inner shelves is investigated with an idealized morphodynamic model. The latter uses the two‐dimensional shallow water equations to describe a storm‐driven flow on an inner shelf with an erodible bottom and a transverse slope. Both bed load and suspended load sediment transport are included. New are the incorporation of a wave module based on physical principles and a critical shear‐stress for erosion. A linear stability analysis is used to study the initial growth of bed forms, by analyzing the initial growth of small perturbations evolving on an alongshore uniform basic state, which describes a storm‐driven flow on a microtidal inner shelf. Model simulations show that wave‐topography interactions cause the ridges to become more trapped to the coast. Both growth and migration of the ridges are controlled by suspended load transport. The physical mechanism responsible for ridge growth is related to transport by the storm‐driven current of sediment that is entrained due to wave orbital motions induced by bed forms. This new mechanism even acts in absence of a transverse bottom slope. The orientation, spacing and shape of the modeled ridges agree well with field observations from different shelves.
Control of salinity on the mixed layer depth in the world ocean: 1. General description
Authors: de Boyer Montégut Clément , Mignot Juliette , Lazar Alban , Cravatte Sophie
Published: June 2007

Using instantaneous temperature and salinity profiles, including recent Argo data, a global ocean climatology of monthly mean properties of the “barrier layer” (BL) phenomenon is constructed. This climatology is based on the individual analysis of instantaneous profiles in contrast with previous large‐scale climatologies derived from gridded fields. This ensures a more accurate description of the BL phenomenon. We distinguish three types of regions: BLs are quasi‐permanent in the equatorial and western tropical Atlantic and Pacific, the Bay of Bengal, the eastern equatorial Indian Ocean, the Labrador Sea, and parts of the Arctic and Southern Ocean. In the northern subpolar basins, the southern Indian Ocean, and the Arabian Sea, BLs are rather seasonal. Finally, BLs are typically never detected between 25° and 45° latitude in each basin. Away from the deep tropics, the analysis reveals strong similarities between the two hemispheres and the three oceans regarding BL seasonality and formation mechanisms. Temperature inversions below the mixed layer are often associated with BLs. Their typical amplitude, depth, and seasonality are described here for the first time at global scale. We suggest that this global product could be used as a reference for future studies and to validate the representation of upper oceanic layers by general circulation models.
Cloud condensation nuclei prediction error from application of Köhler theory: Importance for the aerosol indirect effect
Authors: Sotiropoulou Rafaella‐Eleni P. , Nenes Athanasios , Adams Peter J. , Seinfeld John H.
Published: June 2007

In situ observations of aerosol and cloud condensation nuclei (CCN) and the GISS GCM Model II' with an online aerosol simulation and explicit aerosol‐cloud interactions are used to quantify the uncertainty in radiative forcing and autoconversion rate from application of Köhler theory. Simulations suggest that application of Köhler theory introduces a 10–20% uncertainty in global average indirect forcing and 2–11% uncertainty in autoconversion. Regionally, the uncertainty in indirect forcing ranges between 10–20%, and 5–50% for autoconversion. These results are insensitive to the range of updraft velocity and water vapor uptake coefficient considered. This study suggests that Köhler theory (as implemented in climate models) is not a significant source of uncertainty for aerosol indirect forcing but can be substantial for assessments of aerosol effects on the hydrological cycle in climatically sensitive regions of the globe. This implies that improvements in the representation of GCM subgrid processes and aerosol size distribution will mostly benefit indirect forcing assessments. Predictions of autoconversion, by nature, will be subject to considerable uncertainty; its reduction may require explicit representation of size‐resolved aerosol composition and mixing state.
Global inundation dynamics inferred from multiple satellite observations, 1993–2000
Authors: Prigent C. , Papa F. , Aires F. , Rossow W. B. , Matthews E.
Published: June 2007

Wetlands and surface waters are recognized to play important roles in climate, hydrologic and biogeochemical cycles, and availability of water resources. Until now, quantitative, global time series of spatial and temporal dynamics of inundation have been unavailable. This study presents the first global estimate of monthly inundated areas for 1993–2000. The data set is derived from a multisatellite method employing passive microwave land surface emissivities calculated from SSM/I and ISCCP observations, ERS scatterometer responses, and AVHRR visible and near‐infrared reflectances. The satellite data are used to calculate inundated fractions of equal area grid cells (0.25° × 0.25° at the equator), taking into account the contribution of vegetation to the passive microwave signal. Global inundated area varies from a maximum of 5.86 × 106 km2 (average for 1993–2000) to a mean minimum of 2.12 × 106 km2. These values are considered consistent with existing independent, static inventories. The new multisatellite estimates also show good agreement with regional high‐resolution SAR observations over the Amazon basin. The seasonal and interannual variations in inundation have been evaluated against rain rate estimates from the Global Precipitation Climatology Project (GPCP) and water levels in wetlands, lakes, and rivers measured with satellite altimeters. The inundation data base is now being used for hydrology modeling and methane studies in GCMs.
A compilation of aerosol optical properties and calculation of direct radiative forcing over an urban region in northern China
Authors: Xia X. , Chen H. , Goloub P. , Zhang W. , Chatenet B. , Wang P.
Published: June 2007

Almost 4 years' worth of Aerosol Robotic Network (AERONET) data from Beijing are compiled with historic aerosol data obtained in a few years during the 1980s and 1990s. Aerosol properties, including aerosol optical depth (τ), single scattering albedo (ω) and asymmetry factor (g), show a large day‐to‐day variation and a distinct seasonal pattern. Aerosol loading is at its maximum during the summer and at its minimum during the winter. Aerosol loading frequently increases gradually from the background level to tens of times that of the background level a few days later, then quickly returns to the background level because of the passage of a weather system. Aerosol optical depth at 550 nm (τ550nm) varies from about 0.28 in 1980 to about 0.68 in 2005, implying a significant increase in aerosol loading during the past 25 years. Historic ω and g values are generally in agreement with AERONET data except that aerosol absorption during the winter is quite different. Aerosols induce significant changes in net solar radiation at the surface and at the top of the atmosphere (TOA). The aerosol direct radiative forcing (ADRF) at the surface varies from −17.2 W m−2 in January to −63.5 W m−2 in June and then to −18.5 W m−2 in December. ADRF at the TOA shows a similar seasonal variation to that at the surface, but the value is approximately 28–42% of the latter. A combination of high aerosol optical depth and strong aerosol absorption leads to significant ADRF in the atmosphere, ranging from 1.9 to 117.6 W m−2, thus increasing atmospheric heating by 0.3 to 4.6 K/day. The long‐term change in aerosol loading in China and its effects on climate and the environment deserve much attention.
The role of historical fire disturbance in the carbon dynamics of the pan‐boreal region: A process‐based analysis
Authors: Balshi M. S. , McGuire A. D. , Zhuang Q. , Melillo J. , Kicklighter D. W. , Kasischke E. , Wirth C. , Flannigan M. , Harden J. , Clein J. S. , Burnside T. J. , McAllister J. , Kurz W. A. , Apps M. , Shvidenko A.
Published: June 2007

Wildfire is a common occurrence in ecosystems of northern high latitudes, and changes in the fire regime of this region have consequences for carbon feedbacks to the climate system. To improve our understanding of how wildfire influences carbon dynamics of this region, we used the process‐based Terrestrial Ecosystem Model to simulate fire emissions and changes in carbon storage north of 45°N from the start of spatially explicit historically recorded fire records in the twentieth century through 2002, and evaluated the role of fire in the carbon dynamics of the region within the context of ecosystem responses to changes in atmospheric CO2 concentration and climate. Our analysis indicates that fire plays an important role in interannual and decadal scale variation of source/sink relationships of northern terrestrial ecosystems and also suggests that atmospheric CO2 may be important to consider in addition to changes in climate and fire disturbance. There are substantial uncertainties in the effects of fire on carbon storage in our simulations. These uncertainties are associated with sparse fire data for northern Eurasia, uncertainty in estimating carbon consumption, and difficulty in verifying assumptions about the representation of fires that occurred prior to the start of the historical fire record. To improve the ability to better predict how fire will influence carbon storage of this region in the future, new analyses of the retrospective role of fire in the carbon dynamics of northern high latitudes should address these uncertainties.
Two‐dimensional transverse magnetic scattering using an exact surface admittance operator
Authors: Rogier Hendrik , De Zutter Daniël , Knockaert Luc
Published: June 2007

This paper presents a new approach to solve two‐dimensional transverse magnetic (TM) scattering problems involving homogeneous penetrable scatterers. The scatterers can be replaced by equivalent electric surface currents provided a proper surface admittance operator is introduced relating those currents to the electric fields on the scatterer's surface. The surface operator for a scatterer with rectangular cross section can be determined analytically. The paper emphasizes that the proposed technique remains valid in a complex scattering environment and in the presence of both conducting and nonconducting scatterers. The new method allows for a considerable gain in CPU time and memory requirements and remains very accurate even in the presence of very good conductors and this from the DC regime to the high‐frequency skin effect regime. Scattering of a plane wave by a periodic arrangement of rectangles or crosses embedded in a dielectric slab is used to illustrate the use of the surface admittance operator in conjunction with an integral equation method.
Measuring the stress state of the Saturnian magnetosphere
Authors: Leisner J. S. , Russell C. T. , Khurana K. K. , Dougherty M. K.
Published: June 2007

The dynamics of a planetary magnetosphere can be quantified by subtracting the system's “ground” state from the observed state and tracking their difference. When a magnetosphere is stressed, by external and internal forces, the magnetic field lines become stretched or compressed. In this paper, we construct an index of the stress state of the Saturnian magnetosphere using magnetometer measurements made in the equatorial inner magnetosphere. This index is analogous to the Dst index produced for Earth's magnetosphere and a stress index created for Jupiter from the Galileo magnetometer data. This index identifies infrequent large perturbations of the magnetosphere from its ground state, and the smaller deviations that are consistent in duration and magnitude with those expected from pressure variations in the solar wind.
Summer minimum Arctic sea ice extent and the associated summer atmospheric circulation
Authors: Ogi Masayo , Wallace John M.
Published: June 2007

Interrelationships between year‐to‐year variations in September Arctic sea ice extent and summer sea level pressure and surface air temperature at high northern latitudes are examined making use of microwave satellite imagery and atmospheric data for the period 1979–2006. Linear trends and year‐to‐year variability about the linear trend lines are considered separately: the latter gives a clearer indication of the physical linkages between fields. Years with low September sea ice extent tend to be characterized by anticyclonic circulation anomalies over the Arctic, with easterly wind anomalies over the marginal seas where the year‐to‐year variability of sea ice concentration is largest. It is hypothesized that the summer circulation anomalies cause sea ice extent principally by way of the Ekman drift in the marginal seas. The associated surface air temperature anomalies also tend to be largest over the marginal seas, with positive anomalies over the regions of reduced sea ice.
Measuring heterogeneous remanence in paleomagnetism
Authors: Borradaile Graham J. , Geneviciene Ieva
Published: June 2007

Remanence directions of from the same block‐sample may be inconsistent or unrepresentative due to orientation and location heterogeneity of their remanence‐bearing minerals (RBM). Magnetization‐heterogeneity is usually undetectable at the specimen‐level but we replicated its effects by measuring 8 small specimens with stable magnetizations (8 or 5.2 cm3). These were assembled into a single large multi‐specimen inside 125 cm3 containers that were measured in a Molspin “BigSpin” magnetometer. Large‐specimen remanence directions deflect towards the direction of any strongly magnetized sub‐specimen. Differences between the large‐specimen remanence and that for the group of individually measured sub‐specimens worsened when one sub‐specimen was mis‐oriented. These discrepancies were cancelled or reduced using larger numbers of specimen orientations in the magnetometer. Conventional schemes with 4 or 6 different measurement‐orientations may fail to suppress heterogeneity‐effects whereas our 12‐orientation protocol may succeed. For most specimens, acceptable remanence‐homogeneity is present where similar remanence‐directions are recorded from 4, 6, and 12 different spin‐orientations.
Exceptional European warmth of autumn 2006 and winter 2007: Historical context, the underlying dynamics, and its phenological impacts
Authors: Luterbacher Jürg , Liniger Mark A. , Menzel Annette , Estrella Nicole , Della‐Marta Paul M. , Pfister Christian , Rutishauser This , Xoplaki Elena
Published: June 2007

Updated European averaged autumn and winter surface air temperature (SAT) timeseries indicate that the autumn 2006 and winter 2007 were extremely likely (>95%) the warmest for more than 500 years. In both seasons, the European SAT anomaly is widespread with anomalies up to three standard deviations from normal. The anomalous warmth is associated with strong anticyclonic conditions and warm air advection from south west. Phenological impacts related to this warmth included some plant species having a partial second flowering or extended flowering till the beginning of winter. Species that typically flower in early spring were found to have a distinct earlier flowering after winter 2007.
Adaptive evolution and then what?
Authors: Svanbäck Richard , Pineda-Krch Mario , Doebeli Michael
Published: June 2007

Traits determining ecological interactions and dynamics are generally subject to natural selection. That genetically based individual variation in ecological traits can influence population dynamics has interested population biologist from various perspectives. Population ecologists recognized the need to incorporate individual variation in models of population regulation, while evolutionary biologists wish to understand genetic and evolutionary dynamics, e.g. of life history traits, in density-regulated populations. But how does adaptation in ecological traits affect population dynamics? In this project we investigated how ecological dynamics changes as a consequence of adaptive evolution in ecological traits using an individual-based predator-prey model.
Blockade of gap junction coupling by glycyrrhetinic acids in guinea pig cochlear artery: A whole‐cell voltage‐ and current‐clamp study
Authors: Guan B‐C , Si J‐Q , Jiang Z‐G
Published: June 2007

Background and purpose:

Glycyrrhetinic acids (GAs) are widely used as gap junction blockers, but their efficacy and side effects have not been well determined.

Experimental approach:

Whole‐cell electrical recordings were made from vascular smooth muscle cells (VSMCs) embedded in or dissociated from, guinea pig cochlear artery segments.

Key results:

18β‐ & 18α‐GA concentration‐dependently increased membrane input resistance (Rin) of in situ VSMCs, with a maximal input conductance (Gin=1/Rin) reduction of 92% & 77% and IC50 of 2.0 & 4.4 μM, respectively. 18βGA (30 μM) resulted in a Rin of 2.2 GΩ and Cin of 12 pF, comparable to those of freshly dissociated VSMCs (3.1 GΩ & 6.1 pF). The GAs (≥30 μM) caused a depolarization in VSMCs in situ. In dispersed VSMCs, they both inhibited delayed rectifiers; 18βGA also activated a non‐selective cation conductance while 18αGA inactivated a voltage‐independent K+‐conductance. ACh induced an outward current in VSMCs in situ at −40 mV, with a positive slope I/V relation and a reversal potential near EK. The ACh‐induced current was attenuated by 18β‐ & 18αGA with an IC50 of 4.3 & 7.8 μM, respectively.

Conclusions and Implications:

18βGA blocked the vascular gap junctions, achieving a complete electrical isolation of the recorded VSMC at ≥30 μM while causing a mild depolarization by a complex conductance alteration. 18βGA suppressed the ACh‐induced current in VSMC by blocking the myoendothelial gap junction and by a non‐junctional action. 18αGA at 30‐100 μM failed to fully block the gap junctions while exerting side actions.

British Journal of Pharmacology (2007) 151, 1049–1060; doi:10.1038/sj.bjp.0707244
Influence of rosuvastatin on the NAD(P)H oxidase activity in the retina and electroretinographic response of spontaneously hypertensive rats
Authors: Sicard P , Acar N , Grégoire S , Lauzier B , Bron A M , Creuzot‐Garcher C , Bretillon L , Vergely C , Rochette L
Published: June 2007

Background and purpose:

Retinal complications may be encountered during the development of hypertension as a response to oxidative stress. Statins may reduce the risk of developing hypertension and ocular diseases. We evaluate the effects of rosuvastatin (ROSU) on retinal functionality and oxidative stress levels in normotensive and spontaneously hypertensive rats (SHR).

Experimental approach:

Wistar Kyoto (WKY) and SHR were treated for 3 weeks with rosuvastatin (10 mg kg−1 day−1). Electroretinograms (ERG) were recorded before and after rosuvastatin treatment. Reactive oxygen species (ROS) were determined in the retina with dihydroethidium staining and NAD(P)H oxidase activity was evaluated.

Key results:

Retinal ganglion cell ROS and retinal NAD(P)H oxidase activity were higher in SHR than in WKY rats, respectively (17.1±1.1 vs 10.2±1.2 AU, P<0.01; 38095±8900 vs 14081±5820 RLU mg−1; P<0.05). The ERG b‐wave amplitude in SHR was significantly lower than that in WKY rats. Rosuvastatin reduced SBP in SHR but did not change plasma lipid levels. Rosuvastatin treatment in SHR significantly decreased ROS levels (11.2±1.3, P<0.01), NAD(P)H activity in retinal ganglion cells (9889±4290; P<0.05), and increased retinal plasmalogen content in SHR, but did not modify the ERG response.

Conclusions and implications:

Rosuvastatin, beyond lowering cholesterol levels, was able to lower ROS in the retina induced by hypertension, but without improving retinal function in SHR. These findings point to a complex relationship between ROS in the pathogenesis of retinal disease and hypertension.

British Journal of Pharmacology (2007) 151, 979–986; doi:10.1038/sj.bjp.0707322
Do all angiotensin II type 1 receptor blockers have the same beneficial effects?
Authors: Miura S , Saku K
Published: June 2007

Angiotensin II type 1 (AT1) receptor blockers (ARBs) are highly selective for the AT1 receptor, which is a member of the G protein‐coupled receptor superfamily (GPCRs), and block the diverse effects (hypertension, hypertrophy, heart failure, proteinuria etc.) of angiotensin II. Many ARBs are in clinical use and have been shown to be safe and effective. Over the past several years, reports have discussed the different degrees of the beneficial effects of ARBs. As ARBs do not all have the same effects, the benefits conferred by ARBs may not be class effects. These different effects may be due to differences in the molecular characteristics of ARBs. The results reported by Le et al. in this issue highlight the different characteristics of two ARBs, olmesartan and telmisartan, and suggest that the higher degree of insurmountability, slower dissociation, and higher affinity of olmesartan compared to telmisartan for AT1 receptors may help it to form a tight binding complex with this receptor. A better understanding of the different molecular mechanisms for each ARB could be useful for the treatment of patients.

British Journal of Pharmacology (2007) 151, 912–913; doi:10.1038/sj.bjp.0707324
Diverse inhibitory actions of quaternary ammonium cholinesterase inhibitors onTorpedonicotinic ACh receptors transplanted toXenopusoocytes
Authors: Olivera‐Bravo Silvia , Ivorra Isabel , Morales Andrés
Published: June 2007

Background and purpose:

This work was aimed at comparing and analysing the effects and mechanisms of action of the quaternary ammonium cholinesterase inhibitors (QChEIs) BW284c51, decamethonium and edrophonium, on nicotinic ACh receptor (nAChR) function.

Experimental approach:

nAChRs purified fromTorpedoelectroplax were transplanted to oocytes and currents elicited by ACh (IACh) either alone or in presence of these QChEIs were recorded.

Key results:

None of the QChEIs, by itself, elicited changes in membrane conductance; however, when co‐applied with ACh, all of them decreased IAChin a concentration‐dependent way. The mechanisms of nAChR inhibition were different for these QChEIs. BW284c51 blockade was non‐competitive and voltage‐dependent, although it also affected the nHof the dose‐response curve. By contrast, decamethonium and edrophonium inhibition, at –60 mV, was apparently competitive and did not modify either desensitisation or nH. Decamethonium effects were voltage‐independent and washed out slowly after its removal; by contrast, edrophonium blockade had strong voltage dependence and its effects disappeared quickly after its withdrawal. Analysis of the voltage‐dependent blockade indicated that BW284c51 bound to a shallow site into the channel pore, whereas edrophonium bound to a deeper locus. Accordingly, additive inhibitory effects on IAChwere found among any pairs of these QChEIs.

Conclusions and implications:

The tested QChEIs bound to the nAChR at several and different loci, which might account for their complex inhibitory behaviour, acting both as allosteric effectors and, in the case of BW284c51 and edrophonium, as open channel blockers.

British Journal of Pharmacology(2007)151, 1280–1292. doi:10.1038/sj.bjp.0707329
α3β4‐Nicotinic receptors mediate adrenergic nerve‐ and peptidergic (CGRP) nerve‐dependent vasodilation induced by nicotine in rat mesenteric arteries
Authors: Eguchi S , Miyashita S , Kitamura Y , Kawasaki H
Published: June 2007

Background and purpose:

Previous studies demonstrated that nicotine‐induced endothelium‐independent vasodilation is mediated by perivascular adrenergic nerves and nerves releasing calcitonin gene‐related peptide (CGRPergic nerves). We characterized the nicotinic acetylcholine (ACh) receptor subtype underlying the vasodilation in response to nicotine in rat mesenteric arteries.

Experimental approach:

Rat mesenteric vascular beds without endothelium were contracted by perfusion with Krebs solution containing methoxamine and the perfusion pressure was measured with a pressure transducer.

Key results:

Perfusion of nicotine (1–100 μM) for 1 min caused a concentration‐dependent decrease in perfusion pressure due to vasodilation. Perfusion of (±)‐epibatidine (1–100 nM) (non‐selective agonist) or (−)‐cytisine (1–100 μM) (partial agonist for nicotinic β2 subtype and full agonist for nicotinic β4 subtype) induced vasodilation in a concentration‐dependent manner. Vasodilation induced by nicotine, (−)‐cytisine‐ and (±)‐epibatidine was markedly attenuated by guanethidine (5 μM) and pretreatment with capsaicin (1 μM). Mecamylamine (relatively selective antagonist for α3β4 subtype), but not dihydro‐β‐erythroidine (selective antagonist for α4β2 subtype) or α‐bungarotoxin (selective antagonist for α7 subtype), markedly inhibited nicotine‐induced vasodilation. Nicotine‐induced vasodilation was inhibited by methyllycaconitine at high concentrations (>1 μM), which non‐selectively antagonize nicotinic receptors, while a low concentration of 10 nM, which selectively antagonizes α7 subtype, had no effect. (−)‐Cytisine and (±)‐epibatidine‐induced vasodilation were abolished by mecamylamine

Conclusion and implications:

These results suggest that the nicotinic α3β4 receptor subtype, but not the α7 and α4β2 subtypes, is responsible for the vasodilation in rat mesenteric arteries induced by nicotine‐ and nicotinic ACh receptor agonists through stimulation of adrenergic and CGRPergic perivascular nerves.

British Journal of Pharmacology(2007)151, 1216–1223. doi:10.1038/sj.bjp.0707331
Alteration of mitochondrial membrane potential by Spirulina platensis C‐phycocyanin induces apoptosis in the doxorubicinresistant human hepatocellular‐carcinoma cell line HepG2
Authors: Roy Karnati R. , Arunasree Kalle M. , Reddy Nishant P. , Dheeraj Bhavanasi , Reddy Gorla Venkateswara , Reddanna Pallu
Published: June 2007

C‐PC (C‐phycocyanin) is a water‐soluble biliprotein from the filamentous cyanobacterium Spirulina platensis with potent antioxidant, anti‐inflammatory and anticancerous properties. In the present study, the effect of C‐PC was tested on the proliferation of doxorubicin‐sensitive (S‐HepG2) and ‐resistant (R‐HepG2) HCC (hepatocellular carcinoma) cell lines. These studies indicate a 50% decrease in the proliferation of S‐ and R‐HepG2 cells treated with 40 and 50 μM C‐PC for 24 h respectively. C‐PC also enhanced the sensitivity of R‐HepG2 cells to doxorubicin. R‐HepG2 cells treated with C‐PC showed typical apoptotic features such as membrane blebbing and DNA fragmentation. Flow‐cytometric analysis of R‐HepG2 cells treated with 10, 25 and 50 μM C‐PC for 24 h showed 18.8, 39.72 and 65.64% cells in sub‐G0/G1‐phase respectively. Cytochrome c release, decrease in membrane potential, caspase 3 activation and PARP [poly(ADP‐ribose) polymerase] cleavage were observed in C‐PC‐treated R‐HepG2 cells. These studies also showed down‐regulation of the anti‐apoptotic protein Bcl‐2 and up‐regulation of the pro‐apoptotic Bax (Bcl2‐associated X‐protein) protein in the R‐HepG2 cells treated with C‐PC. The present study thus demonstrates that C‐PC induces apoptosis in R‐HepG2 cells and its potential as an anti‐HCC agent.
Energy extremals and nonlinear stability in a variational theory of a coupled barotropic flow - Rotating solid sphere system
Authors: Lim Chjan C.
Published: June 2007

A new variational principle—extremizing the fixed frame kinetic energy under constant relative enstrophy—for a coupled barotropic flow—rotating solid sphere system is introduced with the following consequences. In particular, angular momentum is transferred between the fluid and the solid sphere through a modeled torque mechanism. The fluid’s angular momentum is therefore not fixed but only bounded by the relative enstrophy, as is required of any model that supports super-rotation. The main results are: At any rate of spin Ω and relative enstrophy, the unique global energy maximizer for fixed relative enstrophy corresponds to solid-body super-rotation; the counter-rotating solid-body flow state is a constrained energy minimum provided the relative enstrophy is small enough, otherwise, it is a saddle point. For all energy below a threshold value which depends on the relative enstrophy and solid spin Ω, the constrained energy extremals consist of only minimizers and saddles in the form of counter-rotating states. Only when the energy exceeds this threshold value can pro-rotating states arise as global maximizers. Unlike the standard barotropic vorticity model which conserves angular momentum of the fluid, the counter-rotating state is rigorously shown to be nonlinearly stable only when it is a local constrained minima. The global constrained maximizer corresponding to super-rotation is always nonlinearly stable.
Two-layer quasigeostrophic potential vorticity model
Authors: Jamaloodeen Mohamed I. , Newton Paul K.
Published: June 2007

We formulate the two-layer quasigeostrophic potential vortex (QGPV) model as an infinite-dimensional Hamiltonian system and apply Noether’s theorem to derive the conservation laws for these equations. The point (singular) vortex QGPV model is also analyzed as a finite-dimensional Hamiltonian system. By virtue of its point symmetries, the invariants for the finite-dimensional system are obtained. The existence of these point symmetries is used to prove the integrability of the three-vortex QGPV problem. We analyze the relative equilibrium configurations for the three-vortex, two-layer problem and study collapsing and merging (collapse in different layers) configurations. We also study two special classes of symmetrical four-vortex QGPV problems and establish their integrability and present some simulations for one of these classes of integrable QGPV four-vortex problems.
Oxygen vacancy formation for transient structures on the CeO2(110) surface at 300 and 750 K
Authors: Herschend Björn , Baudin Micael , Hermansson Kersti
Published: June 2007

Ab initio embedded-cluster calculations have been performed for the CeO2(110) surface using temperature induced structures from molecular dynamics (MD) snapshots. As a first step towards understanding how temperature induced distortions of the surface structure influence the surface oxygen reactivity, the energy cost of removing an O atom from the surface was calculated for 41 snapshots from the MD simulation at 300K. The quantum mechanical embedded-cluster calculations show that already at 300K the dynamics causes significant fluctuations (root mean square of 0.37eV) in the O vacancy formation energy (Evac) while the distribution of the two excess electrons associated with the vacancy is virtually unaffected by the surface dynamics and remains localized on the two Ce ions close to the vacancy. It is also found that the quantum mechanical Evac fluctuations can be reproduced by oxygen vacancy calculations using only the relaxed shell-model force field (FF) itself and the MD geometries. Using the FF as the interaction model, the effect of raising the temperature to 750K and the effect of doping with Ca were investigated for the oxygen vacancy formation.
Study on microwave emission mechanisms on the basis of hypervelocity impact experiments on various target plates
Authors: Ohnishi H. , Chiba S. , Soma E. , Ishii K. , Maki K. , Takano T. , Hasegawa S.
Published: June 2007

It was formerly confirmed by experiment that hypervelocity impacts on aluminum plates cause microwave emission. In this study, we have carried out experiments in order to clarify the mechanism of the emission. The microwave is detected by heterodyne detection scheme at 22 and 2 GHz with an intermediate frequency bandwidth of 500 and 120 MHz, respectively. A nylon projectile is accelerated using a light-gas gun to impact a target. First, aluminum plates with ten different thicknesses ranging from 1 to 40 mm were used as a target, and microwave signals were detected. The experimental results are statistically analyzed assuming a Gaussian distribution of the emitted power. The standard deviation of pulse voltage is calculated to show the existence of two kinds of signals: sharp pulse and thermal noise. It is shown that the emitted energy and the dispersion have a relation with the extent of the target destruction. Next, nylon projectiles are impacted on different metals such as aluminum, iron, and copper. These results suggest that microcracks are essential to microwave emission. Finally, in order to clarify the mechanism of charging and discharging across the microcracks, the experimental results are compared with this model for the following factors: (1) the thermally excited electrons and the emitted power, and (2) the bond dissociation energy of target material and emitted power. The analytical results suggest that electrons are excited thermally and by transition from a crystalline state to an atomic state.
The nature of nitrogen related point defects in common forms of InN
Authors: Butcher K. S. A. , Fernandes A. J. , Chen P. P.-T. , Wintrebert-Fouquet M. , Timmers H. , Shrestha S. K. , Hirshy H. , Perks R. M. , Usher Brian F.
Published: June 2007

The role of point defects related to the presence of excess nitrogen is elucidated for InN thin films grown by different techniques. Elastic recoil detection analysis has shown the presence of excess nitrogen in state-of-the-art InN films. Using x-ray photoelectron spectroscopy and x-ray diffraction it is shown that two distinct forms of point defects can be distinguished; one of these appears to be an interstitial form of nitrogen, common in some forms of polycrystalline InN. The other is associated with a combined biaxial and hydrostatic strain observed for molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) grown films, and may be a mixture of the nitrogen-on-metal antisite defect and lower densities of indium vacancies and interstitial nitrogen. The high density of defects present in all the InN samples examined suggests that stoichiometry related point defects dominate the electrical and optical properties of the material. The difference in the type of point defect observed for polycrystalline (rf sputtered) and epitaxial (MBE and CVD) InN supports existing evidence that the Moss-Burstein effect is not an adequate description of the apparent band-gap difference between InN samples grown by different techniques.