bluuebunny/crossref_metadata_2025 huggingface dataset:
Sea surface temperature variability off southern Brazil and Uruguay as revealed from historical data since 1854
Authors: Zavialov Peter O. , Wainer Ilana , Absy João M.
Published: March 2004

About 300,000 quality‐controlled local reports from ships of opportunity were complemented with the data extracted from global data records to compile monthly series of sea surface temperature (SST) for the period 1854 to 1994 on a grid 1° × 1° in latitude and longitude. These historical data are used to investigate the variability off the coast of southern Brazil and Uruguay in a broad range of temporal scales from seasonal to secular. With respect to behavior at these scales, three distinct areas can be identified in the study region. The first one, located over the shelf and controlled by winter invasions of subantarctic water along with Rio de la Plata and Patos‐Mirim discharges, is characterized by large annual range of SST (7° to over 10°C), energetic mean square variability (from 1.4 to 2.2°C2, after removal of seasonal signal), and an extremely high secular trend toward warming (1.2 to 1.6°C per 100 years), especially in the proximity of the estuaries. The second one, an area of the Brazil Current influence, exhibits smaller annual range (5° to 7°C) and mean square variability (1 to 1.4°C2). The secular trend is from 1° to 1.2°C per 100 years, smaller than observed in the shelf, but still high compared to the global average. The third area, which encompasses the eastern deep ocean part of the region away from the influence of either major currents or coastal discharges, exhibits less energetic variability at all examined scales, as compared to the rest of the region. Everywhere in the region, 50 to 80% of interannual variability is associated with periods smaller than 10 years; however, compared to the rest of the region, the shelf zone is characterized by a relatively large contribution from decadal and interdecadal scales. In austral winter a thermal front forms in the study region, separating warm tropical water associated with the Brazil Current and cold subantarctic water flowing northward on the shelf with an admixture of coastal freshwater discharges. The position of this frontal zone is subject to strong year‐to‐year changes. More than a half of the energy of these migrations resides at periods smaller than 10 years where the spectrum is fairly white. In the interdecadal part of the spectrum, at least three significant individual peaks can be identified, corresponding to periods of 47±2, 27±1, and 18 years.
On the Pacific Ocean regime shift
Authors: Stephens Cathy , Levitus Sydney , Antonov John , Boyer Timothy P.
Published: March 2004

The temporal variability of Pacific Ocean upper ocean heat content is examined for the 1948–1998 period using gridded, objectively analyzed temperature anomaly fields. Results indicate a “regime shift” in upper ocean temperature structure occurred in conjunction with the atmospheric shift in sea level pressure around 1975 leading to warming (cooling) in the eastern (western) equatorial Pacific. The shift is a basin‐wide phenomenon affecting the thermal structure from 60°S to 70°N. EOF analysis of the Pacific Ocean heat content (0–125 m) shows a shift from a relatively cool to a warm state in the equatorial Pacific during the mid‐1970s. Further analysis of the gridded temperature anomaly fields shows equatorial warming to be as much as 1.5°C and a cooling in the North Pacific of 1°C, down to 250 meters, after the mid‐1970s. Overall, the analysis indicates the “regime shift” continues through 1998 with no signs of returning to a cooler phase.
Nitrogen geochemistry of subducting sediments: New results from the Izu‐Bonin‐Mariana margin and insights regarding global nitrogen subduction
Authors: Sadofsky Seth J. , Bebout Gray E.
Published: March 2004

Toward understanding of the subduction mass balance in the Izu‐Bonin‐Mariana (IBM) convergent margin, we present an inventory of N and C concentrations and isotopic compositions in sediments obtained on Ocean Drilling Program (ODP) Legs 129 and 185. Samples from Sites 1149, 800, 801, and 802 contain 5 to 661 ppm total N (organic, inorganic combined) with δ15NAir of −0.2 to +8.2‰ (all δ15N values <+2.5‰ from Site 800). At Site 1149, N content is higher in clay‐rich layers and lower in chert and carbonate layers, and δ15N shows a distinct down‐section decrease from 0 to 120 mbsf (near +8.0 at shallow levels to near +4.0‰). Reduced‐C concentration ranges from 0.02 to 0.5 wt.%, with δ13CVPDB of −28.1 to −21.7‰. The down‐section decreases in δ15N and N concentration (and variations in concentrations and δ13C of reduced C, and Creduced/N) at Site 1149 could help reconcile differences between δ15N values of modern deep‐sea sediments from near the sediment‐water interface and values for forearc metasedimentary rocks. At Site 1149, negative shifts in δ15N, from marine organic values (up to ∼+8‰) toward lower values approaching those for the metasedimentary rocks (+1 to +3‰), are most likely caused by complex diagenetic processes, conceivably with minor effects of changes in productivity and differing proportions of marine and terrestrial organic matter. However, the forearc metamorphic suites (e.g., Franciscan Complex) are known to have been deposited nearer continents, and their lower δ15N at least partly reflects larger proportions of lower‐δ15N terrestrial organic matter. Subduction at the Izu‐Bonin (IB) margin, of a sediment section like that at Site 1149, would deliver an approximate annual subduction flux of 2.5 × 106 g of N and 1.4 × 107 g of reduced C per linear kilometer of trench, with average δ15N of +5.0‰ and δ13C of −24‰. Incorporating the larger C flux of 9.2 × 108 g/yr/linear‐km in carbonate‐rich layers of 1149B (average δ13C = +2.3‰) provides a total C flux of 9.3 × 108 g/yr/linear‐km (δ13C = +1.9‰). Once subducted, sediments are shifted to higher δ15N by N loss during devolatilization, with magnitudes of the shifts depending on the thermal evolution of the margin.
The direct observations of large aerosol radiative forcing in the Himalayan region
Authors: Ramana M. V. , Ramanathan V. , Podgorny I. A. , Pradhan Bidya B. , Shrestha Basanta
Published: March 2004

We show here that absorbing aerosols have led to a large reduction of surface solar radiation during winter over the Himalayan region. Our results are based on radiometric, aerosol and Lidar observations made at three sites in Nepal during winter 2003. The monthly mean aerosol optical depth (AOD) ranged from 0.2 to 0.34 and the TERRA satellite MODIS data reveal that AODs measured over these sites were typical of the entire Himalayan region. The near‐surface aerosol single scattering albedo was in the range from 0.7 to 0.9. The presence of strongly absorbing aerosols resulted in a relatively large diurnal mean aerosol surface radiative forcing efficiency of −73 Wm−2 (per unit optical depth). The seasonal mean reduction in solar flux was as high as 25 Wm−2 and aerosol heating as much as 1 K per day within the first two kilometers.
Unusual upwelling event and current reversal off the Italian Adriatic coast in summer 2003
Authors: Poulain Pierre‐Marie , Mauri Elena , Ursella Laura
Published: March 2004

An exceptional upwelling event occurred near the Conero Promontory along the Italian Adriatic coast between 11 and 23 July 2003, as a result of dominant southeasterly sirocco winds. Contemporarily, surface currents off central and southern Italy reversed to the northwest direction. This peculiar dynamic situation happened when the Adriatic river discharge rates were extremely low due to a prolonged dry season. Satellite images of sea surface temperature and chlorophyll concentration and satellite‐tracked drifters revealed that the upwelling event first appeared northwest of the promontory and then progressed to the southeast. Its offshore extension (20–30 km) includes convoluted filament structures. Surface temperature and ocean color signatures are correlated, indicating that the cold‐upwelled water is rich in nutrients. Coldest temperatures are as low as 18–19°C (8°C lower than the open sea). The northwestward currents reached maximum speeds larger than 40 cm/s inshore of the 20 m‐isobath (<10 km from shore).
Transient response of the Earth's magnetosphere to a localized density pulse in the solar wind: Simulation of traveling convection vortices
Authors: Kataoka Ryuho , Fukunishi Hiroshi , Fujita Shigeru , Tanaka Takashi , Itonaga Masahiro
Published: March 2004

We investigate the transient response of the Earth's magnetosphere‐ionosphere system to a localized density pulse in the solar wind using a magnetohydrodynamic simulation. The simulated ionospheric disturbances exhibit many properties similar to those observed during traveling convection vortices (TCVs). The simulated TCVs are driven by pairs of field‐aligned currents. The generation mechanisms of the field‐aligned currents in the magnetosphere are evaluated in terms of a wave equation of field‐aligned currents. The source current is the inertial current associated with in‐out plasma acceleration in the magnetosphere near the impact region. The inertial current is converted into the field‐aligned current off from the equatorial region via the curvilinear effect. The inhomogeneous effect also generates the field‐aligned current near the inner equatorial region where the sharp gradient of Alfvén speed exists.
Grain sizes of susceptibility and anhysteretic remanent magnetization carriers in Chinese loess/paleosol sequences
Authors: Liu Qingsong , Banerjee Subir K. , Jackson Michael J. , Maher Barbara A. , Pan Yongxin , Zhu Rixiang , Deng Chenglong , Chen Fahu
Published: March 2004

Detailed rock magnetic studies show that susceptibility (mass‐specific χ) and anhysteretic remanent magnetization (ARM) of the Chinese loess/paleosol sequences are carried by almost identical magnetic carriers. Therefore the ratio Δχ/χARM (or equivalently χARM/Δχ, where Δχ is defined as χ − χ0, and χ0 is the intercept susceptibility of the plot of χ versus ARM, and χARM is field‐normalized ARM) can be used to quantify the grain size of χ and ARM carriers. By determining this ratio for three Chinese loess/paleosol profiles (Jiuzhoutai, Yuanbao, and Yichuan) characterized by different degrees of environmentally controlled pedogenesis and sedimentation rates, we show that the lower grain‐size limit of aeolian magnetic particles in the less pedogenically altered loess units is about 100–300 nm, in the finer‐grained pseudosingle domain (PSD) grain‐size range. In contrast, the grain sizes of pedogenically produced magnetic particles for mature paleosols dominantly cover both the superparamagnetic (SP) and single‐domain (SD) ranges. On the basis of plots of Δχ/χARM against Δχ, samples can be divided into four regions (I, II, III, and IV). Region I corresponds to the least pedogenically altered primary loess samples, with Δχ/χARM of 0.165–0.24. Samples in region II, a transition zone between the least altered loess and the onset of development of paleosols, have χ values identical to those in region I but have lower Δχ/χARM of 0.09–0.165. With increasing susceptibility in zone III, Δχ/χARM is positively correlated with Δχ, indicating the gradually increasing influence of SP particles. Finally, in zone IV with Δχ higher than ∼6.5 × 10−7 m3 kg−1, Δχ/χARM is independent of the variations in Δχ, suggesting that Δχ/χARM is totally controlled by the pedogenic finest‐grained particles and the size distribution of these particles remains almost constant. The development of soils in the Chinese loess revealed by these three profiles from three sites can be clearly explained by a continuous process of pedogenesis, increasing from zone I to zone IV. The definition of the pedogenic zones can help to improve our understanding of the underlying mechanisms and variability of pedogenesis and thus could enable more successful and accurate separation of the authentic pedogenic signals from the background signal of the aeolian inputs at different loess sites worldwide.
Scaled temperature spectrum in the unstable oceanic surface layer
Authors: Wijesekera Hemantha W. , Paulson Clayton A. , Skyllingstad Eric D.
Published: March 2004

A nondimensional form of the temperature spectrum in a convective near‐surface layer was derived empirically as a function of stability parameter ξ = z/L and surface wave parameter γ = u*/(gz)1/2, under the assumption of horizontal isotropy, where z is the depth of the measurement, L is the Monin‐Obukhov length scale, u* is the surface friction velocity, and g is the acceleration due to gravity. The wave number‐weighted, one‐dimensional spectrum had +1 slope at low wave numbers and −2/3 slope at high wave numbers (characteristic of an inertial subrange). Spectral levels in the −2/3 range varied with γ, and the spectrum width was a function of ξ. The wavelength of the spectral peak decreased as −ξ (>0) increased. The variation of spectral level in the inertial subrange suggested that dissipation due to wave breaking was enhanced by a factor of 1.7 at 2‐m depth for a wind speed of 10 m s−1. Root‐mean‐square temperature fluctuations at 2‐m depth versus −ξ were in excellent agreement with atmospheric surface layer observations and agreed moderately well (within 30%) with the results of large‐eddy simulation experiments. Root‐mean‐square fluctuations were proportional to (−ξ)−1/3 for −ξ > 0.4, consistent with the predictions of similarity theory. The skewness of temperature fluctuations varied with −ξ, qualitatively similar to variation in the atmospheric surface layer. The skewness of the horizontal gradient of temperature at 2‐m depth varied relative to the wind direction and was well described by a cosine function with amplitude 0.6.
Simulated impact of intraseasonal variations in surface heat and momentum fluxes on the pelagic ecosystem of the Arabian Sea
Authors: Kawamiya Michio , Oschlies Andreas
Published: March 2004

A series of numerical experiments using a three‐dimensional, coupled ecosystem‐circulation model has been performed to evaluate the impact of variations on an “intraseasonal” daily to monthly timescale in surface fluxes of heat and momentum on simulated biological production in the Arabian Sea. The biological component is a four‐compartment, nitrogen‐based system; the physical component is a high‐vertical‐resolution z‐level model that includes a mixed‐layer model based on the turbulent energy equation and contrasts with layer models which often overestimate vertical mixing associated with intraseasonal mixed‐layer retreat and formation. Experiments show that the intraseasonal variations in the forcing may have to be considered when comparing sparsely sampled data with results from a numerical model. The experiments provide, however, no evidence that there is any rectification impact on longer timescales. In particular, accounting for intraseasonal variations has essentially no effect on the simulated annual mean biological production.
Seasonality in precipitation variability over Europe
Authors: Zveryaev Igor I.
Published: March 2004

A gridded monthly and pentad precipitation for 1979–2001 from the Climate Prediction Center Merged Analysis of Precipitation (CMAP) data set and terrestrial monthly gauge‐based precipitation for 1958–1998 from the Climatic Research Unit, University of East Anglia (CRU), data set are used to investigate seasonality in the long‐ and short‐term precipitation variability over Europe. Prominent seasonal differences are detected both in precipitation climatologies and in characteristics of precipitation variability. It is shown that over western Europe the summer precipitation climatology and its year‐to‐year variability (expressed by standard deviations) are lower than those of the winter precipitation. Major seasonal differences are found over central eastern Europe. In this region the summer precipitation climatology and magnitudes of its interannual variability exceed respective winter characteristics by a factor of 2–3.5. Similar relationships are found for the summer and winter magnitudes of intraseasonal fluctuations of precipitation. The first empirical orthogonal function (EOF) modes of both summer and winter seasonal mean precipitation over Europe are associated with the North Atlantic Oscillation (NAO). However, they explain very different (42% for winter and 25% for summer) fractions of total precipitation variability and form principally different spatial patterns. Temporal behavior of the respective principal components is also essentially different. The first EOF mode of the winter magnitudes of intraseasonal precipitation fluctuations is also associated with the NAO. The second EOF mode of the winter precipitation is linked to the East Atlantic teleconnection pattern. However, the respective mode in the magnitudes of intraseasonal fluctuations was not detected. The second EOF mode of the summer precipitation is associated with the 500 hPa heights pattern, which is characterized by four anomaly centers. Two major centers of opposite polarity are located over western Europe and Scandinavia‐northeastern European Russia.
Dynamic winter climate response to large tropical volcanic eruptions since 1600
Authors: Shindell Drew T. , Schmidt Gavin A. , Mann Michael E. , Faluvegi G.
Published: March 2004

We have analyzed the mean climate response pattern following large tropical volcanic eruptions back to the beginning of the 17th century using a combination of proxy‐based reconstructions and modern instrumental records of cold‐season surface air temperature. Warm anomalies occur throughout northern Eurasia, while cool anomalies cover northern Africa and the Middle East, extending all the way to China. In North America, the northern portion of the continent cools, with the anomalies extending out over the Labrador Sea and southern Greenland. The analyses confirm that for two years following eruptions the anomalies strongly resemble the Arctic Oscillation/Northern Annular Mode (AO/NAM) or the North Atlantic Oscillation (NAO) in the Atlantic‐Eurasian sector. With our four‐century record, the mean response is statistically significant at the 95% confidence level over much of the Northern Hemisphere land area. However, the standard deviation of the response is larger than the mean signal nearly everywhere, indicating that the anomaly following a single eruption is unlikely to be representative of the mean. Both the mean response and the variability can be successfully reproduced in general circulation model simulations. Driven by the solar heating induced by the stratospheric aerosols, these models produce enhanced westerlies from the lower stratosphere down to the surface. The climate response to volcanic eruptions thus strongly suggests that stratospheric temperature and wind anomalies can affect surface climate by forcing a shift in the AO/NAM or NAO.
Temporal scaling of hydraulic head and river base flow and its implication for groundwater recharge
Authors: Zhang You‐Kuan , Schilling Keith
Published: March 2004

Spectral analyses were conducted for hourly hydraulic head (h) data observed over a 4‐year period at seven monitoring wells in the Walnut Creek watershed, Iowa. The log power spectral density of the hydraulic head fluctuations versus log frequency (f) at all seven wells is shown to have a distinct slope or fractal dimension (D), indicating temporal scaling in the time series of water level fluctuations. The fractal dimension of the time series varies from well to well, and the spectrum for the average h over all seven wells has a fractal dimension of 1.46 and Hurst coefficient of 0.54. The log power spectral density of estimated base flow in the Walnut Creek and four other watersheds versus log f is shown to have two distinct slopes with a break in scaling at about 30 days. It is shown that the groundwater recharge process in a basin can be estimated from a head spectrum based on existing theoretical results. Hydraulic head in an aquifer may fluctuate as a fractal in time in response to either a white noise or fractal recharge process, depending on physical parameters (i.e., transmissivity and specific yield) of the aquifer. The recharge process at the Walnut Creek watershed is shown to have a white noise spectrum based on the observed head spectrum.
Detection of a slow slip event from small signal in GPS data
Authors: Sato Tamao , Imanishi Kazutoshi , Kato Naoyuki , Sagiya Takeshi
Published: March 2004

By correcting for seasonal noise contained in GPS data, we are able to detect small but compelling post‐seismic deformation following a medium‐sized interplate earthquake (2001 August 14, MW 6.4) that occurred off the Pacific coast of northern Honshu, Japan. Its decaying‐time constants are similar among the stations with an average of 2.2 months. We inverted for the slip distribution, assuming that post‐seismic deformation was due to a slow slip near the main shock fault. Slow slip spreads mainly over the northern periphery of the northern asperity of the 1968 Tokachi‐Oki earthquake (MW 8.2) that has been considered a seismic gap since 1994. The seismic moment of the slow slip is about three times greater (MW 6.7) than that of the co‐seismic slip. The present case suggests that the post‐seismic slow‐slip is common not only for the large earthquakes but also for relatively small interplate earthquakes in this region.
Application of flux‐corrected transport to the Las Cruces Trench site
Authors: Hills R. G. , Fisher K. A. , Kirkland M. R. , Wierenga P. J.
Published: March 2004

A flux‐corrected transport (FCT) based numerical algorithm is developed to model the solute transport equation in heterogeneous variably saturated soils. The fully Eulerian algorithm is designed to model very steep gradients without the characteristic numerical diffusion/dispersion found in standard finite difference schemes. This algorithm can handle both small and infinite grid Peclet numbers but is limited to grid Courant numbers less than or equal to 0.5. Since useful results can be obtained for infinite Peclet numbers, the algorithm can be used to trace water movement when coupled with a numerical model for Richards' equation. We used the FCT based algorithm in conjunction with Richards' equation to model a hypothetical experiment at the Las Cruces Trench site. In this numerical experiment, water with tracer is applied across the top of a 24‐m‐wide domain. The two‐dimensional distribution for the hydraulic properties estimated during site characterization is used to define the soil model. The predicted flow and tracer transport is quite complex. The movement of the wetting front appears to be heavily influenced by the old water, whereas the new water tends to bypass much of the old water indicating preferential flow.
Estimation of Moments and Quantiles using Censored Data
Authors: Kroll Charles N. , Stedinger Jery R.
Published: March 2004

Censored data sets are often encountered in water quality investigations and streamflow analyses. A Monte Carlo analysis examined the performance of three techniques for estimating the moments and quantiles of a distribution using censored data sets. These techniques include a lognormal maximum likelihood estimator (MLE), a log‐probability plot regression estimator, and a new log‐partial probability‐weighted moment estimator. Data sets were generated from a number of distributions commonly used to describe water quality and water quantity variables. A “robust” fill‐in method, which circumvents transformation bias in the real space moments, was implemented with all three estimation techniques to obtain a complete sample for computation of the sample mean and standard deviation. Regardless of the underlying distribution, the MLE generally performed as well as or better than the other estimators, though the moment and quantile estimators using all three techniques had comparable log‐space root mean square errors (rmse) for censoring at or below the 20th percentile for samples sizes ofn=10, the 40th percentile forn=25, and the 60th percentile forn=50. Comparison of the log‐space rmse and real‐space rmse indicated that a log‐space rmse was a better overall metric of estimator precision.
Nonlinear analysis of river flow time sequences
Authors: Porporato Amilcare , Ridolfi Luca
Published: March 2004

Within the field of chaos theory several methods for the analysis of complex dynamical systems have recently been proposed. In light of these ideas we study the dynamics which control the behavior over time of river flow, investigating the existence of a low‐dimension deterministic component. The present article follows the research undertaken in the work ofPorporato and Ridolfi[1996a] in which some clues as to the existence of chaos were collected. Particular emphasis is given here to the problem of noise and to nonlinear prediction. With regard to the latter, the benefits obtainable by means of the interpolation of the available time series are reported and the remarkable predictive results attained with this nonlinear method are shown.
Influence of Amodiaquine Treatment on Microsomal Lipid Peroxidation and Antioxidant Defense Systems of Rats
Authors: Farombi E. Olatunde
Published: March 2004

The effects of single and multiple doses amodiaquine treatment on enzymatic and non‐enzymatic antioxidant profiles and hepatic microsomal lipid peroxidation were investigated in rats. Treatment of rats with 10 mg/kg (single dose) amodiaquine resulted in 10% and 63% increases, respectively in the activities of liver superoxide dismutase and glutathione peroxidase (P<0.01), while the activity of liver catalase was significantly reduced by 26% compared to control. The levels of serum vitamins A, C and β‐carotene were lowered following amodiaquine treatment. Following multiple dose (10 mg/kg for 4 consecutive days) amodiaquine treatment, activities of superoxide dismutase and glutathione peroxidase were increased by 30% and 133% respectively while catalase activity was decreased by 45%. Similarly, serum vitamins A, C and β‐carotene levels were markedly decreased. In the single dose study, the levels of malondialdehyde and the activity of glutathione S‐transferase were increased by 15% and 44% respectively while the reduced glutathione was decreased by 25% compared to control. Malondialdehyde level was highly increased (P<0.001) by 71% following multiple amodiaquine treatment. Reduced glutathione was decreased by 55% and unlike in the single dose study, activity of glutathione S‐transferase was decreased by 60% compared to control. The activities of serum aspartate amino transferase, alanine amino transferase, ornithine carbamyl transferase and γ‐glutamyl transferase were significantly increased by both single and multiple doses of amodiaquine treatment (P<0.01). The alteration in enzymatic and non‐enzymatic antioxidant defense system, increase in lipid peroxidation and increase in the activities of serum enzymes following amodiaquine treatment suggests damage to the liver and could subject the organ to further oxidative stress. The relevance of this to continuous exposure to amodiaquine therapy should be considered.
Effect of Tetrandrine on Experimental Hepatic Fibrosis Induced by Bile Duct Ligation and Scission in Rats
Authors: Park Pil‐Hoon , Nan Ji‐Xing , Park Eun‐Jeon , Kang Hee‐Chul , Kim Ji‐Young , Ko Geonil , Sohn Dong Hwan
Published: March 2004

Tetrandrine, an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to elicit antifibrotic effects in various cell types. In the present study, the effect of tetrandrine on liver fibrosis was investigated by using bile duct ligation and scission in rats as a model of hepatic fibrosis. Treatment with tetrandrine in fibrotic rats reduced serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels to 72%, 52% and 51% that of controls at 10 mg/kg/day, respectively. Liver hydroxyproline contents in tetrandrine‐treated rats with bile duct ligation and scission were also reduced to 65% of that of control rats with bile duct ligation and scission at 10 mg/kg/day. The morphological characteristics of fibrotic liver, which appeared in control bile duct ligation and scission group, were improved in tetrandrine‐treated bile duct ligation and scission group. We also examined the effect of tetrandrine on cultured rat hepatic stellate cells, which plays an important role in the pathogenesis of hepatic fibrosis, activation to investigate whether it could act mainly by direct action on rat hepatic fibroblastic cells. In cultured rat hepatic stellate cells, tetrandrine reduced DNA synthesis to 57% of control hepatic stellate cells at 10 μg/ml without affecting cell viability. Smooth muscle‐α‐actin expression, the phenotypic marker of activated hepatic stellate cells, was also decreased. We conclude that tetrandrine has an antifibrotic effect on liver fibrosis in rats induced by bile duct ligation and scission, indicating that it might exert a direct effect on rat hepatic stellate cells.
Local Transfer of Diazepam, but Not of Cocaine, from the Nasal Cavities to the Brain Arterial Blood in Rats
Authors: Einer‐Jensen Niels , Larsen Lise
Published: March 2004

Nasal administration to rats of small molecules (tritiated water, tyrosine, and propanol) results in a higher concentration in the brain arterial blood than in other arteries. The preferential distribution is based on a counter current transfer, which takes place between nasal vein blood and brain arterial blood in the cavernous sinus – carotid artery complex. The present experiments attempt to document that drugs may also be transferred by this system. Groups of 10 large male rats were anaesthetised and intubated. Two catheters were inserted into the same carotid artery, one tip pointing towards the head, the other towards the heart. Parallel blood samples were obtained every 30 sec. for 10 min. after nasal administration of radioactively labelled diazepam or cocaine, and the plasma radioactivity measured. Control groups received the drugs intravenously. The uptake of diazepam was rapid, while cocaine uptake was slow. The average ratio between the radioactivity of parallel samples (R: “Head” plasma/“Heart” plasma) in rats treated with nasal diazepam was 1.12±0.04, 181 (average±S.E.M., n) for the whole 10 min. period and 1.20±0.05, 96 for the second half of the sampling period. The increase of 12 and 20% is highly significant. The intravenous ratio for diazepam and both R's for the cocaine groups were not significantly different from 1.00. The present experiments show that nasal administration of diazepam induces a relatively higher concentration in the brain arterial blood than in parallel samples obtained from another artery. A preferential, first‐pass distribution to the brain after nasal administration of diazepam may thus exist.
Inhibiting Effect of Ammonia on Citric Acid‐Induced Cough in Pigs: A Possible Involvement of Substance P
Authors: Moreaux Benoit , Nemmar Abderrahim , Beerens Dominique , Gustin Pascal
Published: March 2004

The effect of ammonia on the cough response to citric acid and on substance P release from C‐fibers involved in this reflex was assessed. For a period from one to four days, piglets were exposed, in an inhalation chamber, to ammonia at a concentration of 15 or 30 ppm. During exposure, cough induction tests were done every two days. Recovery of the cough reflex after ammonia exposure was also determined. In a separate group of piglets exposed for 2 days to 30 ppm ammonia, substance P content was determined in bronchial and tracheal lavage fluids and in the tracheal and bronchial mucosa. Ammonia (30 ppm) was found to inhibit coughing significantly (the cough frequency was reduced by 64%) after a two‐day exposure. In animals exposed for 4 days to this ammonia concentration, the recovery ranged from 3 to 7 days (mean: 5 days). The same ammonia concentration also caused the substance P content to increase significantly in broncho‐alveolar lavage fluid (to 432% of its initial value) and tracheal lavage fluid (to 149%) and to decrease significantly in the tracheal mucosa (‐58%), however the content in bronchial mucosa was not significantly affected (−43%). Exposure to 15 ppm ammonia had no effect on the frequency of citric acid‐induced coughing. In conclusion, ammonia inhibits citric acid‐induced coughing in pigs at concentrations that can be detected in piggeries. This inhibitory effect may be related to substance‐P depletion in C‐fiber endings.
Hepatic Disposition of Neurotoxins and Pesticides
Authors: Yang Maria C. , McLean Allan J. , Rivory Laurent P. , Le Couteur David G.
Published: March 2004

The hepatic disposition of pesticides and neurotoxins may influence susceptibility to Parkinson's disease. Therefore we examined the behaviour of paraquat, dichlorodiphenyltrichloroethane (DDT), malathion and 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) in perfused rat liver using the multiple indicator‐dilution technique. The values for the recovery of paraquat, DDT, malathion and MPTP were 1.05±0.12, 0.32±0.01, 0.11±0.02 and 0.02±0.01, respectively. The volumes of distribution were 0.28±0.13, 0.69±0.12, 3.30±0.58 and 5.10±6.00 ml/g, respectively. The permeability‐surface area products suggest that transport of DDT and MPTP across cell membranes is by simple diffusion. However, there may be a specific influx mechanism for malathion and a specific efflux mechanism for paraquat. There is considerable variability in the hepatic disposition of putative neurotoxins such as MPTP and pesticides. Factors that influence the hepatic disposition of neurotoxins may alter susceptibility to neurotoxic diseases however the effects will be diverse.
Regressor and random‐effects dependencies in multilevel models
Authors: Ebbes Peter , Böckenholt Ulf , Wedel Michel
Published: March 2004

The objectives of this paper are (1) to review methods that can be used to test for different types of random effects and regressor dependencies, (2) to present results from Monte Carlo studies designed to investigate the performance of these methods, and (3) to discuss estimation methods that can be used when some but not all of the random effects and regressor independence assumptions, are violated. Because current methods are limited in various ways, we will also present a list of open problems and suggest solutions for some of them. As we will show, the issue of regressor random‐effects independence has received some attention in the econometrics literature, but this important work has had little impact on current research practices in the social and behavioral sciences.
Testing homogeneity in a random intercept model using asymptotic, posterior predictive and plug‐inp‐values
Authors: Kato Bernet Sekasanvu , Hoijtink Herbert
Published: March 2004

In this paper three statistics and three discrepancy measures with which homogeneity in the random intercept model can be investigated will be evaluated. The first two can be used to test the homogeneity of level one residual variances across level two units and the third can be used to test whether effects should be fixed or random. Each statistic and discrepancy measure will be evaluated using asymptotic (if available), posterior predictive and plug inp‐values. A simulation study will be used to investigate the frequency properties of thesep‐values. In the discussion it will be indicated how the results obtained for the random intercept model with one explanatory variable can be useful during the construction of general two level models.
An EM algorithm for the estimation of parametric and nonparametric hierarchical nonlinear models
Authors: Vermunt Jeroen K.
Published: March 2004

It is shown how to implement an EM algorithm for maximum likelihood estimation of hierarchical nonlinear models for data sets consisting of more than two levels of nesting. This upward–downward algorithm makes use of the conditional independence assumptions implied by the hierarchical model. It cannot only be used for the estimation of models with a parametric specification of the random effects, but also to extend the two‐level nonparametric approach – sometimes referred to as latent class regression – to three or more levels. The proposed approach is illustrated with an empirical application.
Deletions in an endopolygalacturonase gene cluster correlate with non-melting flesh texture in peach
Authors: Callahan Ann M. , Scorza Ralph , Bassett Carole , Nickerson Michael , Abeles Frederick B.
Published: March 2004

Endopolygalacturonase activity during softening of peach [Prunus persica (L.) Batsch] fruit is thought to be responsible for the melting flesh texture. A cDNA, PRF5, was previously identified as a fruit-related endopolygalacturonase that may be involved with the texture differences (Lester et al. 1996). We found that all eight of the non-melting flesh cultivars in this study had a deletion in at least one of their PRF5-related polygalacturonase genes, while none of the melting flesh cultivars did. There were three sources of the non-melting trait, as identified by the extent of the deletions. One source of non-melting flesh resulted in a complete deletion of PRF5-related genes while the other two sources had deletions of a subset of those genes, suggesting a cluster of polygalacturonase genes at the melting flesh locus. All of the non-melting flesh cultivars used for this study had greatly reduced or undetectable mRNA levels of PRF5-related polygalacturonase during fruit softening. Using PCR techniques, it was determined that either the PRF5 gene, or more likely, an unidentified peach polygalacturonase at the same locus, is responsible for melting flesh texture determination.
Comparison of solvent regimes for the extraction of photosynthetic pigments from leaves of higher plants
Authors: Dunn Jodie L. , Turnbull Johanna D. , Robinson Sharon A.
Published: March 2004

The relative efficiency of methanol- and acetone-based solvents for the extraction of pigments from photosynthetic tissues of plant was compared, together with the advantages of multiple versus single extractions. The two commonly employed triple acetone extractions (100 : 80 : 80% and 85 : 100 : 100%) performed comparably for most pigments and for all plant species tested. Single extractions with either 96% methanol or 85% acetone failed to extract the more hydrophobic pigments, especially β-carotene. We conclude that multiple extractions that combine pure and aqueous (80–85%) acetone are preferable for extraction of the full range of pigments. These results suggest that previous studies that have utilised aqueous methanol (especially in a single extraction) have probably underestimated the concentration of β-carotene relative to other pigments.
Is ‘five-a-day’ an effective way of increasing fruit and vegetable intakes?
Authors: Ashfield-Watt PAL , Welch AA , Day NE , Bingham SA
Published: March 2004

Objectives:

To assess whether the amount of fruits and vegetables consumed depends on the serving size or on how often fruits and vegetables are eaten.

Design:

Estimation of the weight of serving sizes and the number of fruits and vegetables eaten daily, using a validated food diary method.

Setting:

Free-living men and women participating in the Norfolk arm of the European Prospective Investigation into Cancer and Nutrition (EPIC).

Subjects:

Two hundred and sixty-nine men and women sampled from EPIC–Norfolk to participate in a study of simple methods of assessing fruit and vegetable intakes.

Results:

The average portion of all fruits and vegetables measured was 87 g, close to the standard portion size of 80 g used as the basis of ‘5-a-day’ recommendations. There was a wide variation; the average portion size for baked beans was 147 g while for lettuce it was 26 g. The 20th and 80th percentiles also showed a large range, e.g. 39–72 g for carrots and 60–150 g for strawberries. Women ate more fruit than did men but fewer vegetables, so the total amount of fruit and vegetables eaten by men and women was the same. High consumers of fruits and vegetables (≥400 g day-1) ate them ~5 times a day whilst low consumers (<400 g day-1) ate them less often (~3 servings per day,P<0.01). Portion size differed little between high and low consumers.

Conclusions:

Frequency of intake is more important than portion size when distinguishing between high and low consumption of fruits and vegetables. Therefore, to increase intakes, low consumers should eat fruits and vegetables more often. This endorses the ‘5-a-day’ healthy eating message.
Demographic, familial and trait predictors of fruit and vegetable consumption by pre-school children
Authors: Cooke L J , Wardle J , Gibson EL , Sapochnik M , Sheiham A , Lawson M
Published: March 2004

Objective:

To examine the contribution to fruit and vegetable eating in children of potential predictive variables within the domains of demographics, parental feeding practices and personality traits.

Design:

Cross-sectional survey.

Setting:

Questionnaires were distributed to parents through 22 London nursery schools.

Subjects:

Questionnaires were completed and returned by 564 parents or principal caregivers of 2–6-year-old children.

Results:

Significant predictors of children's fruit and vegetable intake emerged from all three domains examined. Demographic variables associated with child's vegetable consumption were mother's education and child's age and gender. Only ethnicity was significantly associated with fruit consumption. Parental consumption, breast-feeding and early introduction to fruit and vegetables were related to intake of both. Family mealtimes were associated with higher intake of vegetables, but not of fruit. Two characteristics of children themselves (food neophobia and enjoyment of food) were strongly related to the consumption of fruit and vegetables. Subsequent multivariate analyses revealed that parental intake and child food neophobia independently predicted intake of both foods. In the presence of these, fruit consumption was affected by breast-feeding and early introduction to fruit, whereas vegetable consumption was related only to child's gender and enjoyment of food.

Conclusions:

These findings may be used to inform future interventions aimed at increasing children's consumption of fruit and vegetables. Parents should be made aware of the possible impact of their own behaviour on the eating habits of their children.
Tracing ingestion of ‘novel’ foods in UK diets for possible health surveillance – a feasibility study
Authors: Robertson Claire , Best Nicky , Diamond Judith , Elliott Paul
Published: March 2004

Objective:

To investigate the feasibility of using commercially available data on household food consumption to carry out food and nutritional surveillance.

Design:

Taylor Nelson Sofres (TNS) collects information on foods brought home for consumption among a representative quota sample of the British population. In total, 33 177 households and 105 667 individuals provided data between 1991 and 2000. These were used to investigate sociodemographic, geographical and temporal trends in purchase patterns of the main macronutrients and four groups of marker products.

Results:

Sociodemographic characteristics of the TNS sample were broadly consistent with those of the British population. Estimated energy intakes were slightly low (1667±715 kcal) in comparison with other national data. However, percentage energy contributions were consistent with national trends: e.g. consumption of alcohol in the home increased between 1991 and 2000 with higher intakes among more affluent households, while fat intakes decreased slightly over the same period. Significant temporal, geographic and socio-economic trends were found for all nutrients (P< 0.0001). Intakes of marker products were sparse (purchased by <4% of households), but significant variations were detected in the proportion of households purchasing some or all of the marker products across temporal, geographic and socio–economic strata.

Conclusions:

A prospective nutrient surveillance system could be used to trace consumption patterns of foods or nutrients to inform nutritional surveillance. However, existing data sources would require a number of modifications to increase their suitability for such a project. Increasing surveillance to consider ingredients would require the development of a central coding system, with electronically linked barcode, ingredient and nutrient information.
The epidemiology of good nutritional status among children from a population with a high prevalence of malnutrition
Authors: Pryer Jane A , Rogers Stephen , Rahman Ataur
Published: March 2004

Objectives:

To identify socio-economic demographic and environmental factors that predict better height-for-age for children under 5 years of age in a Dhaka slum population.

Design:

A panel survey, conducted between 1995 and 1997. A random sample of households was selected. Socio-economic, demographic and environmental variables were collected monthly by questionnaire and nutritional status was assessed.

Setting:

Dhaka slums in Bangladesh.

Subjects:

Three hundred and ninety-two children, surveyed in September–November 1996.

Main outcome measures:

Height-for-ageZ-score (HAZ) above −2.

Results:

Thirty-one per cent of children had HAZ <−2. Logistic regression adjusted for cluster sampling showed that better nourished children were more likely to have taller mothers, to be from female-headed households and from families with higher income, electricity in the home, better latrines, more floor space and living in Central Mohammadpur. Better nourished children were less likely to have fathers who have taken days off from work due to illness.

Conclusions:

Interest in ‘positive deviance’ is motivated by the recognition that a focus on the malnourished only – the bottom tail of the distribution – provides indications of how families fail, but not of how they succeed in maintaining child nutrition in the face of adversity. Our analysis provides an alternative perspective on nutrition and vulnerability in an urban slum setting.
A comparison of dietary habits among women in Japan and Hawaii
Authors: Takata Yumie , Maskarinec Gertraud , Franke Adrian , Nagata Chisato , Shimizu Hiroyuki
Published: March 2004

Objective:

To compare the dietary habits of Japanese women in Japan with those of Japanese and Caucasian women living in Hawaii.

Design:

Data from two previous cross-sectional studies conducted within two years in Hawaii and Gifu, Japan were pooled and analysed. Dietary intakes were assessed with validated food-frequency questionnaires and urine samples were collected for isoflavone measurement.

Setting:

Participants were recruited through mammography clinics in both locations.

Subjects:

In Hawaii, 164 Caucasian and 146 Japanese women; in Japan, 206 women.

Results:

Dietary habits differed considerably by ethnicity and location. In comparison to the Caucasian diet, the diet in Japan was relatively low in fat and high in carbohydrates and protein, whereas the Japanese women in Hawaii reported intermediate intakes. Japanese women in Gifu consumed a diet that was relatively high in fish, soy, eggs and vegetables, and low in fruits, dairy products and meat. In contrast, the Caucasian women consumed the most dairy products and fruits and the Japanese women in Hawaii reported the highest grain and meat intakes.

Conclusions:

The diet of Japanese women in Hawaii appeared to be a combination of foods eaten in Japan and the dietary habits of Caucasian women in Hawaii, but eating habits in Japan are also different from traditional nutritional patterns. This study illustrates several problems related to dietary comparisons across populations and provides information for future investigations on chronic disease risk.