bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of maternal plasma volume expansion and antihypertensive treatment with intravenous dihydralazine on fetal and maternal hemodynamics during pre‐eclampsia: a clinical, echo‐Doppler and viscometric study
Authors: Boito S. M. E. , Struijk P. C. , Pop G. A. M. , Visser W. , Steegers E. A. P. , Wladimiroff J. W.
Published: March 2004

Objectives

To establish the effects of plasma volume expansion (PVE) followed by intravenous dihydralazine (DH) administration on maternal whole blood viscosity (WBV) and hematocrit, uteroplacental and fetoplacental downstream impedance and umbilical venous (UV) volume flow in pre‐eclampsia.

Methods

In 13 pre‐eclamptic women maternal and fetal hemodynamics were established by means of combined measurement of maternal arterial blood pressure (BP), WBV, hematocrit and uterine artery (UtA) resistance index (RI) in addition to umbilical artery (UA) pulsatility index (PI) and UV volume flow obtained from UV vessel area and UV time‐averaged flow velocity. In each woman all parameters were measured four times at baseline, after PVE, after DH and 24 h after the start of treatment.

Results

Maternal diastolic BP, hematocrit and WBV display a significant reduction after PVE. In the fetus UA PI decreases significantly whereas a significant increase in UV cross‐sectional area was detected. After maternal DH administration, arterial systolic and diastolic BP and UA PI show a significant decrease compared with the measurements following PVE. At 24 h, only maternal systolic and diastolic BP display a significant further decrease. No significant changes were established for the UtA RI, UV time‐averaged velocity and UV volume flow during the entire study period.

Conclusions

During pre‐eclampsia, maternal PVE followed by DH administration results in a significant reduction in maternal diastolic BP, maternal hematocrit and WBV. Maternal PVE is associated with a significant increase in UV cross‐sectional area and a non‐significant rise of 11% in UV volume flow. Maternal DH administration does not result in any change in UV cross‐sectional area. However, UA PI decreases significantly after both PVE and DH treatment. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal brain imaging: a comparison between magnetic resonance imaging and dedicated neurosonography
Authors: Malinger G. , Ben‐Sira L. , Lev D. , Ben‐Aroya Z. , Kidron D. , Lerman‐Sagie T.
Published: March 2004

Objectives

To evaluate whether fetal brain magnetic resonance imaging (MRI) adds useful clinical information to that obtained by dedicated fetal neurosonography using a combined transabdominal and transvaginal approach in fetuses with suspected brain anomalies.

Methods

In the 2‐year period between January 2000 and January 2002, 42 fetuses underwent neurosonographic and MRI examinations of the brain. The referral indications were: asymmetric ventriculomegaly (13), ventriculomegaly (7), periventricular cysts (2), suspected midline findings (7), agenesis of the corpus callosum (3), infratentorial pathology (3), cytomegalovirus (CMV) infection (2) and miscellaneous indications (5).

Results

Neurosonography and MRI produced similar diagnoses in 29 fetuses: normal examination (10), isolated asymmetric ventriculomegaly (11), isolated ventriculomegaly (3), periventricular cysts (2), agenesis of the corpus callosum (1), pericallosal lipoma (1) and cerebellar hemorrhage (1). The neurosonographic diagnoses were more accurate in seven patients: hemimegalencephaly, pericallosal lipoma, signs of CMV infection, brain anomalies associated with agenesis of the corpus callosum and three fetuses with a normal ultrasound scan in which MRI suggested a parenchymal abnormality. MRI provided a more accurate diagnosis in three patients: a third ventricular dilatation was ruled out, normal ventricles in a fetus with an ultrasonographic finding of asymmetric ventricles, and diagnosis of progression of asymmetric ventriculomegaly. In three patients the identified pathologies were differently interpreted, each examination provided another aspect of the anomaly or a definitive diagnosis was not possible.

Conclusions

Our study demonstrated that dedicated neurosonography is equal to MRI in the diagnosis of fetal brain anomalies. In most of the cases MRI confirmed the ultrasonographic diagnosis; in a minority of cases each modality provided additional/different information. The major role of MRI was in reassurance of the parents regarding the presence or absence of brain anomalies. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Severe fetal cytomegalovirus infection associated with cerebellar hemorrhage
Authors: Ortiz J. U. , Ostermayer E. , Fischer T. , Kuschel B. , Rudelius M. , Schneider K. T. M.
Published: March 2004

Cytomegalovirus (CMV) is the most common cause of congenital infection worldwide. We report on a fatal fetal manifestation of primary maternal CMV infection including cerebellar hemorrhage and hydrops. The diagnosis was established by maternal serological tests, culture and polymerase chain reaction testing of amniotic fluid and fetal blood. The pregnancy was terminated. Postmortem examination confirmed the diagnosis. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal sonographic features of a rhabdoid tumor of the kidney
Authors: Fuchs I. B. , Henrich W. , Kalache K. D. , Lippek F. , Dudenhausen J. W.
Published: March 2004

Rhabdoid tumors of the kidney are highly lethal malignancies of infancy. We report the prenatal detection of a renal rhabdoid tumor with mesoblastic components in a fetus at 27 weeks of gestation. The tumor presented as a large mass in the left renal area and there was concomitant massive polyhydramnios. Though the sonographic features alone did not allow distinction from a benign lesion, the aggressive tumor growth indicated malignancy. Amniotic fluid cytology was performed but failed to confirm the diagnosis. Corticosteroids were administered for lung maturation. Tocolysis, including betamimetics, magnesium and indomethacin, was performed to prevent premature labor. Additionally, serial amniodrainage was performed. At 30 weeks of gestation fetal hydrops developed and a Cesarean section was performed. After delivery, ventilation of the preterm infant was insufficient due to diaphragm elevation by the huge tumor, requiring immediate tumor surgery. However, though ventilation was improved the infant died of cardiac failure 4 h after surgery. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Double‐chamber right ventricle associated with severe fetal cardiac failure
Authors: Becker S. , Hofbeck M. , Kendziorra H. , Wallwiener D. , Mielke G.
Published: March 2004

Fetal cardiac defects leading to intrauterine cardiac failure and subsequent fetal hydrops are rare. We report an unusual case of a double‐chamber right ventricle leading to progressive fetal cardiac insufficiency and hydrops. The patient was first managed conservatively. Delivery by Cesarean section was performed for a pathological fetal heart‐rate tracing at 28 weeks of gestation. The newborn died 4 h postpartum due to generalized cardiac insufficiency. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Chromosomal abnormalities in fetuses with open neural tube defects: prenatal identification with ultrasound
Authors: Sepulveda W. , Corral E. , Ayala C. , Be C. , Gutierrez J. , Vasquez P.
Published: March 2004

Objectives

To determine the prevalence of chromosomal abnormalities in fetuses with open neural tube defects (NTD) undergoing prenatal chromosome analysis. The role of prenatal ultrasound in detecting those with an underlying chromosomal abnormality was also investigated.

Methods

Over a 6‐year period, 144 fetuses with open NTD underwent prenatal chromosome analysis between 12 and 37 weeks of gestation, as part of a prospective, multicenter prenatal diagnosis and counseling program in Chile. This population included 66 fetuses with spina bifida, 46 with acrania/anencephaly, 21 with cephalocele and 11 with iniencephaly. A confident prenatal diagnosis was made in 143 fetuses (99%) and confirmed postnatally in all cases.

Results

An underlying chromosomal abnormality was diagnosed in 10 fetuses (7%), six with spina bifida, three with cephalocele and one with craniorachischisis. The prevalence of chromosomal abnormality varied according to the defect present in the fetus, with a 14% (3/21) prevalence among those with cephalocele, 9% (6/66) among those with spina bifida and 2% (1/57) among those with lethal defects such as acrania, anencephaly or iniencephaly. Karyotype results revealed trisomy 18 in seven cases, trisomy 13 in two and mosaicism for a marker chromosome in one. Prenatal ultrasound before the procedure showed that all chromosomally abnormal fetuses had additional findings. The prevalence of chromosomal abnormality in fetuses with spina bifida and cephalocele was higher when chromosome analysis was performed at or before 24 weeks of gestation in comparison to those performed after 24 weeks (5/31 (16%) vs. 4/56 (7%), respectively). However, this difference did not reach statistical significance, probably due to the small number of cases.

Conclusions

A significant number of fetuses with open NTD are chromosomally abnormal. Although prenatal chromosome analysis should be considered in all cases, prenatal ultrasound seems effective in identifying those fetuses with an underlying chromosomal abnormality. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
CLUSTER observations of lower hybrid waves excited at high altitudes by electromagnetic whistler mode signals from the HAARP facility
Authors: Bell T. F. , Inan U. S. , Platino M. , Pickett J. S. , Kossey P. A. , Kennedy E. J.
Published: March 2004

We report new observations from the CLUSTER spacecraft of strong excitation of lower hybrid (LH) waves by electromagnetic (EM) whistler mode waves at altitudes ≥20,000 km outside the plasmasphere. Previous observations of this phenomenon occurred at altitudes ≤7000 km. The excitation mechanism appears to be linear mode coupling in the presence of small scale plasma density irregularities. These observations provide strong evidence that EM whistler mode waves are continuously transformed into LH waves as the whistler mode waves propagate at high altitudes beyond L ∼ 4. This may explain the lack of lightning generated whistlers observed in this same region of space.
Dynamics of a dissolution front for solids under stress
Authors: Misbah Chaouqi , Renard François , Gratier Jean‐Pierre , Kassner Klaus
Published: March 2004

A kinetic study including dissolution process and diffusion of the dissolved molecules for a stressed solid in contact with its solution is analyzed. We estimate a condition fixing the prevailing dissipation mechanism and analyze it with a linear stability criterion. This criterion depends on which process is limiting the rate of dissipation: dissolution at the solid‐liquid interface or diffusion in the fluid. For definiteness we focus on recent experiments on various salts, which have shown that grooves, oriented perpendicular to the main compressive stress, develop on the free surfaces of crystals. We provide the characteristic length scale and the time scale for the development of this stress‐induced roughening of solid surfaces, which are consistent with the experiments. Finally, we estimate these parameters for relevant geological conditions.
Location of the reconnection line for northward interplanetary magnetic field
Authors: Trattner K. J. , Fuselier S. A. , Petrinec S. M.
Published: March 2004

The interconnection of magnetic fields through magnetic reconnection at the magnetopause is the dominant process for mass, energy, and momentum transfers from the Earth's magnetosheath to the magnetosphere. Earlier studies on the location of the reconnection line during northward interplanetary magnetic field (IMF) conditions and high solar wind dynamic pressure revealed an approximately equal probability for antiparallel and component reconnection between the IMF and the geomagnetic field. Using data from the Toroidal Imaging Mass Angle Spectrograph on the Polar spacecraft, we have substantially increased our survey, selecting only events with northward IMF but no restrictions on the solar wind dynamic pressure. The distance to the reconnection line is calculated using the proven method of three‐dimensional cuts of the proton distribution function in the cusp to identify the low‐velocity cutoffs of precipitating and mirrored ion populations. Antiparallel and component reconnections are identified by tracing this calculated distance to the reconnection site back along the geomagnetic field to the magnetopause, where the draped IMF is used to calculate the magnetopause shear angle. We find that both reconnection scenarios, antiparallel and component reconnections, occur for the same IMF conditions. The observation of either antiparallel or component reconnection depends entirely on the location of the observing spacecraft.
Heliospheric plasma sheets
Authors: Crooker N. U. , Huang C.‐L. , Lamassa S. M. , Larson D. E. , Kahler S. W. , Spence H. E.
Published: March 2004

As a high‐beta feature on scales of hours or less, the heliospheric plasma sheet (HPS) encasing the heliospheric current sheet shows a high degree of variability. A study of 52 sector boundaries identified in electron pitch angle spectrograms in Wind data from 1995 reveals that only half concur with both high‐beta plasma and current sheets, as required for an HPS. The remaining half lack either a plasma sheet or current sheet or both. A complementary study of 37 high‐beta events reveals that only 5 contain sector boundaries while nearly all (34) contain local magnetic field reversals, however brief. We conclude that high‐beta plasma sheets surround current sheets but that most of these current sheets are associated with fields turned back on themselves. The findings are consistent with the hypothesis that high‐beta plasma sheets, both at and away from sector boundaries, are the heliospheric counterparts of the small coronal transients observed at the tips of helmet streamers, in which case the proposed mechanism for their release, interchange reconnection, could be responsible for the field inversions.
Orientation and motion of a discontinuity from single‐spacecraft measurements of plasma velocity and density: Minimum mass flux residue
Authors: Sonnerup B. U. Ö. , Haaland S. , Paschmann G. , Lavraud B. , Dunlop M. W. , Rème H. , Balogh A.
Published: March 2004

A simple analytical solution is presented to the problem of determining the orientation and motion of a one‐dimensional discontinuity in plasma velocity and density, measured by a single spacecraft as the discontinuity moves past it. The method developed is called Minimum Massflux Residue (MMR). Illustrations of the method, based on Cluster measurements in the dawnside magnetopause region, are given, and the results are compared with those obtained by other methods, such as Minimum Faraday Residue (MFR) analysis and minimum variance analysis of the magnetic field combined with deHoffmann‐Teller frame determination (MVAB/HT). The results indicate that the Cluster plasma measurements are of sufficiently high quality for MMR to yield normal vectors and magnetopause speeds that agree well with those obtained from MFR and also from a constrained version of MVAB/HT (the constraint being 〈B〉 · n = 0). We also show how results from more than one method can be combined to produce a single prediction of the normal vector and speed.
Three‐dimensional roughness of stylolites in limestones
Authors: Renard François , Schmittbuhl Jean , Gratier Jean‐Pierre , Meakin Paul , Merino Enrique
Published: March 2004

Stylolites are dynamic roughly planar surfaces formed by pressure solution of blocks of rocks into each other. The three‐dimensional geometry of 12 bedding‐parallel stylolites in several limestones was measured using laser and mechanical profilometers, and statistical characteristics of the surfaces were calculated. All the stylolites analyzed turn out to have self‐affine fractal roughness with a well‐characterized crossover length scale separating two self‐affine regimes. Strikingly, this characteristic length scale falls within a very narrow range for all the stylolites studied, regardless of the microstructure sizes. To explain the data, we propose a continuous phenomenological model that accounts for the development of the measured roughness from an initially flat surface. The model postulates that the complex interface morphology is the result of competition between the long‐range elastic redistribution of local stress fluctuations, which roughen the surface, and surface tension forces along the interface, which smooth it. The model accounts for the geometrical variability of stylolite surfaces and predicts the dependence of the crossover length scale on the mechanical properties of the rock.
Joint two‐dimensional DC resistivity and seismic travel time inversion with cross‐gradients constraints
Authors: Gallardo Luis A. , Meju Max A.
Published: March 2004

It is now common practice to perform collocated DC resistivity and seismic refraction surveys that complement each other in the search for more accurate characterization of the subsurface. Although conventional separate DC resistivity and seismic models can be diagnostic, we posit that better results can be derived from jointly estimated models. We make the assumption that both methods must be sensing the same underlying geology and have developed an innovative resistivity‐velocity cross‐gradients relationship to evaluate the structural features common to both methods. The cross‐gradients function is incorporated as a constraint in a nonlinear least squares problem formulation, which is solved using the Lagrange multiplier method. The resultant iterative two‐dimensional (2‐D) joint inversion scheme is successfully applied to synthetic data (serving as validation tests here) and to field data from collocated DC resistivity and seismic refraction profiling experiments and also compared to conventional separate inversion results. The joint inversion results are shown to be superior to those from separate 2‐D inversions of the respective data sets, since our algorithm leads to resistivity and velocity models with remarkable structural agreement.
Spreading velocities and dilution of North Atlantic Deep Water in the tropical Atlantic based on CFC time series
Authors: Steinfeldt Reiner , Rhein Monika
Published: March 2004

Repeated observations of CFC‐11 and CFC‐12 in the western tropical Atlantic over the period from 1990 to 2002 are used to fit parameters of the age spectra for several North Atlantic Deep Water components: the upper Labrador Sea water (ULSW), the Labrador Sea water (LSW), and the lower North Atlantic Deep Water (LNADW). The most robust results are the mean spreading velocities, u, from the formation region in the Labrador Sea and the Denmark Strait, of 1.5 ± 0.3 cm/s for the two LSW water masses and 2.0 ± 0.2 cm/s for LNADW, respectively. These values are equivalent to an age of about 15–22 years for all three components at 16°N and 21–31 years at the equator at 35°W. The results are compatible with simpler tracer methods, as CFC ratios or “effective” ages. The fractions, f, of the “young” component (i.e., the fraction of the water mass ventilated in the last 50 years), turned out to be quite small, ranging from 25% to less than 5%. The downstream decrease of f indicates mixing of young NADW with CFC‐poor older NADW vintages and/or mixing with other CFC‐free water masses from the Southern Hemisphere. The lowest fractions were found in the LNADW, with a sharp downstream decrease from the equator at 35°W to 10°S, probably caused by the bifurcation into a zonal flow along 2°S and a southward flow along the Brazilian coast. Unlike the small uncertainties estimated for the inferred velocities, isopycnal diffusivities, κ, range from 100 to 10000 m2/s. The temporal evolution of f in the LSW shows a maximum, propagating from 7°N in 1996, downstream to 5°S in the Deep Western Boundary Current, and along 2°S to 23°W. We interpret this signal as the arrival of the intensely ventilated LSW formed in 1972–1976. Decreasing fractions of the ULSW and LSW south of the equator between 2000 and 2002 are presumably caused by local dynamics.
Cross‐shore sediment transport under breaking solitary waves
Authors: Kobayashi Nobuhisa , Lawrence Andrew R.
Published: March 2004

Laboratory experiments were performed to examine the cross‐shore sediment transport processes under breaking solitary waves on a fine sand beach. The initial beach slope of 1/12 was exposed to a positive solitary wave eight times. The beach was rebuilt and exposed to a negative solitary wave eight times. The wave motion and sediment transport were not affected much by the beach profile change from the initial profile. The positive solitary wave plunged violently near the shoreline and suspended a considerable volume of sand. The plunging wave with no seaward flow impeding its run‐up caused large run‐up on the foreshore. The strong downrush following the large run‐up resulted in erosion on the foreshore and deposition seaward of wave run‐down. On the other hand, the negative solitary wave collapsed against the seaward flow induced by the free surface slope of the negative wave and caused less sediment suspension. The wave run‐up against the seaward flow was much smaller. The weak downrush following the small run‐up resulted in deposition on the foreshore and erosion near the wave collapsing point. These limited laboratory experiments indicate the importance of the initial wave profile for swash sediment dynamics and the capacity of a single wave in causing noticeable beach profile changes.
Dehydration in the tropical tropopause layer: Implications from the UARS Microwave Limb Sounder
Authors: Read W. G. , Wu D. L. , Waters J. W. , Pumphrey H. C.
Published: March 2004

Measurements of H2O from the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) are used to investigate the structure of H2O in the near tropopause region and dehydration mechanisms in the tropical tropopause layer (TTL). The new MLS data are consistent with convective input of H2O into the bottom of the TTL followed by slow ascent with a maximum relative amplitude in the seasonal cycle occurring near the tropopause nearly in phase with the tropopause temperature seasonal cycle. The relative amplitude of the seasonal cycle shows a minimum at 121 hPa in the upwelling moist phase. These features are reproduced with the “cold‐trap” dehydration hypothesis. Seasonal maps show wettest tropical 100 hPa H2O colocated with continental convection.
Deliquescence of malonic, succinic, glutaric, and adipic acid particles
Authors: Parsons Matthew T. , Mak Jackson , Lipetz Sarah R. , Bertram Allan K.
Published: March 2004

In order to understand and predict the role of organic particles in the atmosphere their deliquescence behavior must be understood. Using an optical microscope coupled to a flow cell, we investigated the deliquescence of malonic, succinic, glutaric, and adipic acid particles with sizes ranging from 2 to 40 μm. Deliquescence relative humidities were determined for temperatures ranging from 293 to 243 K. Over this temperature range both succinic acid and adipic acid deliquesced at approximately 100% relative humidity, whereas malonic acid and glutaric acid deliquesced at significantly lower relative humidities. These results are generally in good agreement with previous studies and are within 3% of calculations based on the UNIQUAC (universal quasi‐chemical) Functional Group Activity Coefficients (UNIFAC) model and recently published interaction parameters. Our studies also include measurements at temperatures below the eutectic temperatures. At these temperatures, ice did not nucleate; rather the particles underwent deliquescence to form metastable solution droplets. This indicates that solid dicarboxylic acids are not good ice nuclei above 243 K and hence will probably not play a role in ice cloud formation at these temperatures.
Seasonal variations of sulfate, carbonaceous species (black carbon and polycyclic aromatic hydrocarbons), and trace elements in fine atmospheric aerosols collected at subtropical islands in the East China Sea
Authors: Kaneyasu Naoki , Takada Hideshige
Published: March 2004

In order to characterize the outflow of pollution derived aerosols from the Asian Pacific rim to the North Pacific Ocean, seasonal variations of fine aerosol components (aerodynamic diameter <2 μm) were collected at two islands (Amami Island and Miyako Island) that surround the East China Sea. Monthly averaged concentrations of non‐sea‐salt SO42− (nss.SO42−) and black carbon (BC) at Amami and Miyako showed relatively high values in winter to spring and low values in summer. The observed seasonal variation is basically determined by the northwesterly monsoon in winter to spring and southeasterly wind from the stationary North Pacific anticyclone in summer. The minimum concentration levels of nss.SO42− and BC in summer were almost 2–3 times that of the North Pacific background level. Trace metals in aerosols showed similar seasonal variations observed for nss.SO42− and BC. The concentrations of nss.SO42− and Sb were highly correlated; this is in contradiction with the results at stations established in Pacific Exploratory Mission‐West ground monitoring sites. Polycyclic aromatic hydrocarbons (PAHs) also showed a pronounced maximum in winter and/or spring, with maximum concentrations comparable in magnitude to those in spring at Barrow, Alaska. Many of the low molecular weight species of PAHs had high correlation with BC, suggesting that they were either transported independently in a similar way or were transported attached to BC. Furthermore, the relative abundance of some PAH species in the present study and those found in deep‐ocean surface sediments sampled in the middle Pacific Ocean are compared and discussed.
Atmospheric tar balls: Particles from biomass and biofuel burning
Authors: Pósfai Mihály , Gelencsér András , Simonics Renáta , Arató Krisztina , Li Jia , Hobbs Peter V. , Buseck Peter R.
Published: March 2004

“Tar balls” are amorphous, carbonaceous spherules that occur in the tropospheric aerosol as a result of biomass and biofuel burning. They form a distinct group of particles with diameters typically between 30 and 500 nm and readily identifiable with electron microscopy. Their lack of a turbostratic microstructure distinguishes them from soot, and their morphology and composition (∼90 mol % carbon) renders them distinct from other carbonaceous particles. Tar balls are particularly abundant in slightly aged (minutes to hours old) biomass smoke, indicating that they likely form by gas‐to‐particle conversion within smoke plumes. The material of tar balls is initially hygroscopic; however, the particles become largely insoluble as a result of free radical polymerization of their organic molecules. Consequently, tar balls are primarily externally mixed with other particle types, and they do not appreciably increase in size during aging. When tar balls coagulate with water‐bearing particles, their material may partly dissolve and no longer be recognizable as distinct particles. Tar balls may contain organic compounds that absorb sunlight. They are an important, previously unrecognized type of carbonaceous (organic) atmospheric particle.
Validation of CFC‐12 measurements from the Improved Limb Atmospheric Spectrometer (ILAS) with the version 6.0 retrieval algorithm
Authors: Khosrawi F. , Müller R. , Irie H. , Engel A. , Toon G. C. , Sen B. , Aoki S. , Nakazawa T. , Traub W. A. , Jucks K. W. , Johnson D. G. , Oelhaf H. , Wetzel G. , Sugita T. , Kanzawa H. , Yokota T. , Nakajima H. , Sasano Y.
Published: March 2004

Measurements of CFC‐12 were made by the Improved Limb Atmospheric Spectrometer (ILAS) between 57°N and 72°N in the Northern Hemisphere and between 64°S and 89°S in the Southern Hemisphere. ILAS was launched on 17 August 1996 on board the Advanced Earth Observing Satellite (ADEOS). The ILAS validation balloon campaigns were carried out from Kiruna, Sweden (68°N, 21°E), in February and March 1997 and from Fairbanks, Alaska (65°N, 148°W), in April and May 1997. During these validation balloon campaigns, CFC‐12 was measured with the in situ instruments ASTRID, BONBON, and SAKURA and the remote sensing spectrometers MIPAS‐B, FIRS‐2, and MkIV. ILAS version 6.0 CFC‐12 profiles obtained at the nearest location to the validation balloon measurement are compared with these validation balloon measurements. The quality of ILAS CFC‐12 data processed with the version 6.0 algorithm improved significantly compared to previous versions. Low relative differences between ILAS CFC‐12 and the correlative measurements of about 10% were found between 13 and 20 km. The comparison of vertical profiles shows that ILAS CFC‐12 data are useful below about 20–22 km inside the vortex and below about 25 km outside the vortex. However, at greater altitudes the relative percentage difference increases very strongly with increasing altitude. Further, correlations of CFC‐12 with N2O show a good agreement with the correlative measurements for N2O values of N2O > 150 ppbv. In summary, ILAS CFC‐12 data are now suitable for scientific studies in the lower stratosphere.
Identification of dissolution patterns in nannofossil assemblages: A high‐resolution comparison of synchronous records from Ceara Rise, ODP Leg 154
Authors: Gibbs Samantha J. , Shackleton Nicholas J. , Young Jeremy R.
Published: March 2004

Fossil nannoplankton assemblages are controlled by both initial plankton production and dissolution throughout the water column and on the seafloor. It is usually assumed that dissolution can be identified by subjective visual assessment of preservation state. We have tested this by a quantitative comparison of mid‐Pliocene nannofossil assemblages in two closely located ODP sites, Ceara Rise Sites 926 and 929, both with apparently good preservation but located respectively above and below the lysocline. We demonstrate that, despite an absence of obvious qualitative preservation differences, dissolution has removed perhaps 80% of the assemblage in the sub‐lysocline Site 929. This has produced consistent distortions in the assemblages and artificially enhanced abundance variations patterns of individual species. The results provide strong cautions for palaeoceanographic interpretation of nannofossil data and allow us to uniquely extract a dissolution variation record and provide a detailed ranking of dissolution susceptibility of Pliocene nannofossils.
Fractured porous media under influence: The Roselend Experiment
Authors: Provost A.‐S. , Richon P. , Pili E. , Perrier E. , Bureau S.
Published: March 2004

The deformation of the crust and fluid rock interactions are both important problems in the Earth sciences. Observing and measuring these coupled phenomena will improve our understanding of geologic processes acting in fractured porous media and the transfer properties of fluids. These observations can be made via laboratory experiments, but the sample scale is not always satisfying for understanding crustal‐scale phenomena.

On the contrary, monitoring a natural site at the field‐scale provides clues that are directly interpretable in terms of geologic phenomena. The Roselend Experiment is one such endeavor that provides a setting for a multidisciplinary research project. Its goal is to determine transfer processes and transient phenomena at different scales in space and time within a highly dynamic system that is submitted to mechanical, hydrologic, meteorological, and thermal forces.
Climate reconstructions: Low‐frequency ambition and high‐frequency ratification
Authors: Esper Jan , Frank David C. , Wilson Robert J. S.
Published: March 2004

The assessment of past temperature variations and the magnitude and characteristics of recent warmth relative to warm periods in pre‐industrial times—for example, during the Medieval Warm Period (MWP)—have critical implications for understanding and quantifying the forcing of climate in natural and anthropogenic conditions. The desire to benchmark past climate variability of the northern hemisphere has resulted in four millennial‐length temperature reconstructions with annual resolution [Briffa, 2000; Esper et al., 2002; Jones et al., 1998; Mann et al., 1999].

These records, however, provide different perspectives on the above issues. For example, the temperature amplitude reconstructed by Esper et al. [2002] is about 1°C, approximately twice that of Mann et al. [1999] and Jones et al. [1998]. Additionally, Briffa [2000] and Esper et al. [2002] display a pronounced MWP followed by a significant 200‐300‐year‐long cooling trend associated with the Little Ice Age. Such a trend is broadly absent in Mann et al. [1999] and Jones et al. [1998].
Stable water usage, but some groundwater concerns, USGS report indicates
Authors: Showstack Randy
Published: March 2004

Water use in the United States has remained fairly stable since 1985, according to an 11 March report by the U.S. Geological Survey. The report, which estimates water use for the year 2000—the most recent available data—indicates that Americans used an estimated 408 billion gallons of water per day an amount the agency said would fill 8 billion bathtubs daily.

This also translates into 1,430 gallons per person per day when including electric power generation, irrigation, and personal use.
“Comet‐chaser” spacecraft launched
Authors: Jacobs Judy
Published: March 2004

The European Space Agency successfully launched its Rosetta spacecraft on 2 March, the beginning of what is hoped will be a 10‐year journey that will provide information about the origins of the solar system, by placing a lander on the nucleus of comet 67/P Churyumov‐Gerasimenko. Rosetta was launched from the ESAs facility at Kourou, French Guiana.

After three flybys of the Earth and one of Mars, Rosetta is scheduled, in mid‐2011, to ignite its main engine for a major deep‐space maneuver that will place it onto an intercept trajectory with the comet.
Investigating the structural evolution of the western Baltic
Authors: Hübscher C. , Lykke‐Andersen H. , Hansen M. Bak , Reicherter K.
Published: March 2004

The western Baltic Sea, located along the northern margin of the Central European Basin System (CEBS), is a world‐class site for investigating the dynamics and stratigraphic evolution of a continental basin with marine geophysical data acquisition techniques. The universities of Aarhus and Hamburg have joined forces to investigate the post‐Permianto‐recent structural evolution of the western Baltic, with special emphasis on neotectonic re‐activation along major structural lineaments.

Deep crustal structures of the CEBS are well established from previous studies. However, no systematic and localized research has yet been carried out to investigate the neotectonic activity in this region. In fact, the limited seismic resolution of previously available data prevented detailed research on Mesozoic and Cenozoic evolution or neotectonics.
Jackson receives 2003 Hydrology Section Award
Authors: Lakshmi Venkat , Jackson Thomas J.
Published: March 2004

Thomas J. Jackson received the Hydrology Section Award at the 2003 AGU Fall Meeting in San Francisco, California, last December. The award recognizes outstanding contributions to the science of hydrology.
Focusing on seismology education
Authors: Hamburger Michael , Taber John
Published: March 2004

Question: What happens when you lock 50 scientists, educators, and science outreach specialists in a hotel for 3 days? Answer: The birth of an exciting new science education initiative!

A secluded site in Baltimore was the gathering place for nearly 50 U.S.‐based seismologists, K‐12 teachers, science education scholars, and science policy leaders with interests in science outreach and education.
A virtual publications forum
Authors: Hornberger George , Bougeret Jean‐Louis , Bowring Samuel , Collins Curtis , Costa John , Jackson Robert , Jaumann Ralf , Stein Ross , Suyehiro Kiyoshi , Zeng Xubin
Published: March 2004

As part of the continuing effort to inform members about the publications program and get their input, the Publications Committee scheduled an open forum at the 2003 AGU Fall Meeting. This was to allow any members or guests the opportunity to ask questions about the AGU publications program, processes, progress, or any other publications‐related concerns. Here, we are using the pages of Eos to share several “good news” messages about AGU publications and open a dialogue with the membership about the publications program.

The first thing to remember about AGU publications is that historically they have supported many of the non‐revenue generating activities of the Union that we hold to be important. Examples include workshops for high school teachers, career information for pre‐college students and school counselors, and information for the press and for decision‐makers at various levels of government. Publications are very important to the mission of AGU, both intellectually and financially (Figure 1).
Handbook of Scaling Methods in Aquatic Ecology: Measurement, Analysis, Simulation
Authors: Marrasé Celia
Published: March 2004

Researchers in aquatic sciences have long been interested in describing temporal and biological heterogeneities at different observation scales. During the 1970s, scaling studies received a boost from the application of spectral analysis to ecological sciences. Since then, new insights have evolved in parallel with advances in observation technologies and computing power. In particular, during the last 2 decades, novel theoretical achievements were facilitated by the use of microstructure profilers, the application of mathematical tools derived from fractal and wavelet analyses, and the increase in computing power that allowed more complex simulations. The idea of publishing the Handbook of Scaling Methods in Aquatic Ecology arose out of a special session of the 2001 Aquatic Science Meeting of the American Society of Limnology and Oceanography. The edition of the book is timely because it compiles a good amount of the work done in these last 2 decades.
Polar Lows: Mesoscale Weather Systems in the Polar Regions
Authors: Bromwich David H.
Published: March 2004

Ten expert authors have combined to provide a comprehensive summary of the status of knowledge, circa 2000, about “polar lows” in both polar regions. The term “polar low” is normally reserved for small but fairly intense maritime cyclones that dominantly form in the northern oceans during winter, as cold air crosses regions of sharp sea surface temperature gradients. This synthesis covers the full spectrum of mesoscale lows with a diameter less than 1000 km that occur in the Arctic and Antarctic poleward of the main polar front. These features typically form and develop in data‐sparse areas, so heavy reliance is placed on satellite remote sensing and numerical modeling to describe and understand these storms. Only a small number of systems have been directly sampled by aircraft. A particularly strong and attractive aspect of Polar Lows is the plethora of satellite images that illustrate the wide range of cloud signatures.
Elasticity of single crystal and polycrystalline MgSiO3 perovskite by Brillouin spectroscopy
Authors: Sinogeikin Stanislav V. , Zhang Jianzhong , Bass Jay D.
Published: March 2004

The elastic moduli of MgSiO3 perovskite have been measured on both single‐crystal and polycrystalline samples by Brillouin spectroscopy at ambient conditions. The aggregate elastic moduli calculated from measured single‐crystal elastic moduli and from the average polycrystalline velocities are in excellent agreement. This convincingly demonstrates that accurate values of elastic moduli can be obtained for polycrystalline samples of dense anisotropic materials by Brillouin spectroscopy. Our new values of the bulk modulus (KS = 253(3) GPa) and shear modulus (μ = 175(2) GPa) are ∼4% and ∼1% lower than commonly accepted values for end‐member MgSiO3 perovskite (KS = 264 GPa, μ = 177 GPa). These lower elastic moduli suggest that the pressure, temperature, and compositional dependence of elastic moduli and wave velocities for magnesian silicate perovskite must be reevaluated in order to obtain reliable constraints on the mantle chemistry and thermal structure.
Positive and Negative Tropic Curvature Induced by Microbeam Irradiation of Protonemal Tip Cells of the Moss Ceratodon purpureus
Authors: Lamparter T. , Kagawa T. , Brücker G. , Wada M.
Published: March 2004

Abstract: The photoreceptor phytochrome mediates tropic responses in protonemata of the moss Ceratodon purpureus. Under standard conditions the tip cells grow towards unilateral red light, or perpendicular to the electrical vector of polarized light. In this study the response of tip cells to partial irradiation of the apical region was analysed using a microbeam apparatus. The fluence response curve gave an unexpected pattern: whereas a 15‐min microbeam with light intensities around 3 μmol m‐2 s‐1 induced a growth curvature towards the irradiated side, higher light intensities around 100 μmol m‐2 s‐1 caused a negative response, the cells grew away from the irradiated side. This avoidance response is explained by two effects: the light intensity is high enough to induce photoconversion into the active Pfr form of phytochrome, not only on the irradiated but also on the non‐irradiated side by stray light. At the same time, the strong light on the irradiated side acts antagonistically to Pfr. As a result of this inhibition, the growth direction is moved to the light‐avoiding side. Such a Pfr‐independent mechanism might be important for the phototropic response to distinguish between the light‐directed and light‐avoiding side under unilateral light.
The Biophysical Basis of Cell Elongation and Organ Maturation in Coleoptiles of Rye Seedlings: Implications for Shoot Development1
Authors: Kutschera U.
Published: March 2004

Abstract: The relationships between changes in irreversible and reversible organ length, turgor (P), osmotic pressure (π), and metabolic activity of the cells were investigated in intact coleoptiles of rye seedlings (Secale cereale L.) that were either grown in darkness or irradiated with continuous white light. Cessation of growth at day 4 after sowing was associated with an apparent mechanical stiffening of the cell walls. Turgor pressure was measured in epidermal and mesophyll cells with a miniaturized pressure probe. No gradient of turgor was found between the peripheral and internal cells. In juvenile (growing) coleoptiles, average turgor was 0.60 MPa and a negative water potential (P ‐ π) was established in these cells. Upon emergence of the primary leaf, turgor declined, but P was maintained at values of 0.43 and 0.52 MPa in 7‐day‐old light‐ and dark‐grown coleoptiles, respectively. Water potential in non‐growing cells approached zero. The rate of dark respiration and elongation growth were not correlated. Surgical removal of the mature coleoptile revealed that the erect position of the 7‐day‐old shoot was dependent on the presence of this sturdy, turgid organ sheath. It is concluded that, during the first week of seedling development, the pierced, metabolically active coleoptile fulfills an essential function as an elastic basal tube for the juvenile shoot.
A Survey of Genetic Diversity and Reproductive Biology of Puya raimondii (Bromeliaceae), the Endangered Queen of the Andes
Authors: Sgorbati S. , Labra M. , Grugni E. , Barcaccia G. , Galasso G. , Boni U. , Mucciarelli M. , Citterio S. , Benavides Iramátegui A. , Venero Gonzales L. , Scannerini S.
Published: March 2004

Abstract: Puya raimondii Harms is an outstanding giant rosette bromeliad found solely around 4000 m above sea level in the Andes. It flowers at the end of an 80 ‐ 100‐year or even longer life cycle and yields an enormous (4 ‐ 6 m tall) spike composed of from 15 000 to 20 000 flowers. It is endemic and currently endangered, with populations distributed from Peru to the north of Bolivia. A genomic DNA marker‐based analysis of the genetic structure of eight populations representative of the whole distribution of P. raimondii in Peru is reported in this paper. As few as 14 genotypes out of 160 plants were detected. Only 5 and 18 of the 217 AFLP marker loci screened were polymorphic within and among these populations, respectively. Four populations were completely monomorphic, each of the others displayed only one to three polymorphic loci. Less than 4 % of the total genomic variation was within populations and genetic similarity among populations was as high as 98.3 %. Results for seven cpSSR marker loci were in agreement with the existence of a single progenitor. Flow cytometry of seed nuclear DNA content and RAPD marker segregation analysis of progeny plantlets demonstrated that the extremely uniform genome of P. raimondii populations is not compatible with agamospermy (apomixis), but consistent with an inbreeding reproductive strategy. There is an urgent need for a protection programme to save not only this precious, isolated species, but also the unique ecosystem depending on it.
Transitions in Photosynthetic Parameters of Midvein and Interveinal Regions of Leaves and Their Importance During Leaf Growth and Development
Authors: Walter A. , Rascher U. , Osmond B.
Published: March 2004

Abstract: The areal development of photosynthetic efficiency and growth patterns in expanding leaves of two different dicotyledonous species ‐ Coccoloba uvifera and Sanchezia nobilis ‐ was investigated by imaging both processes repeatedly over 32 days. Measurements were performed using combined imaging systems for chlorophyll fluorescence and growth, with the same spatial resolution. Significant differences in potential quantum yield of photosynthesis (Fv/Fm), a parameter indicating the functional status of photosystem II, were found between midvein and interveinal tissue. Although base‐tip gradients and spatial patchiness were observed in the distribution of relative growth rate, neither midvein nor interveinal tissue showed such patterns in Fv/Fm. In young leaves, Fv/Fm of the midvein was higher than Fv/Fm of interveinal tissue. This difference declined gradually with time, and upon cessation of growth, Fv/Fm of interveinal regions exceeded those of midvein tissue. Images of chlorophyll fluorescence quenching showed that ΔF/Fm′ in the different tissues correlated with Fv/Fm, indicating that, in these uniformly illuminated leaves, transitions in photosynthetic electron transport activity follow those of predawn quantum efficiency. We explore the implications of these observations during leaf development, discuss effects of sucrose delivery from veins to interveinal areas on relative rates of photosynthetic development in these tissues, and propose that the initially higher photosynthetic activity in the midvein compared to the intervein tissues may supply carbohydrates and energy for leaf growth processes.