bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined dynamic contrast enhanced breast MR and proton spectroscopic imaging: A feasibility study
Authors: Jacobs Michael A. , Barker Peter B. , Argani Pedram , Ouwerkerk Ronald , Bhujwalla Zaver M. , Bluemke David A.
Published: December 2004

Purpose

To investigate the feasibility of combined dynamic contrast enhanced (DCE) and magnetic resonance spectroscopy (MRS) in evaluating breast lesions.

Methods

Nine patients with positive mammograms scheduled for either biopsy or mastectomy were examined on a 1.5‐T MR scanner. DCE was performed with administration of gadolinium‐DTPA contrast using a two‐dimensional spoiled gradient recall echo (SPGR) sequence. Proton spectroscopy (TR/TE = 2000/272 msec) was performed using PRESS single slice (10 mm). Lesion time intensity curves were classified as persistent (type 1), plateau (type 2), or washout (type 3) pattern enhancement. Choline (Cho) signal‐to‐noise ratios (SNRs) and enhancement patterns were compared between benign and malignant lesions as determined by histopathology.

Results

Five patients had breast carcinoma and four had benign lesions. Type 1 enhancement was found in two benign cases, type 2 enhancement in two of four benign and four of five malignant lesions, and one malignant case exhibited a type 3 pattern. Choline SNR was significantly different (P < 0.003) between benign and malignant lesions (2.0 ± 0.3 vs. 5.7 ± 1.4; P < 0.003). Choline SNR was less than 4.0 in all of the benign lesions, including the two lesions with type 2 enhancement.

Conclusion

Proton MRS appears to be a promising technique for classification of breast lesions when DCE results are equivocal. A combination of DCE and MRS is feasible, and may have improved specificity compared to either modality alone. J. Magn. Reson. Imaging 2005;21:23–28. © 2004 Wiley‐Liss, Inc.
Contrast‐enhanced peripheral MR angiography using SENSE in multiple stations: Feasibility study
Authors: de Vries Marianne , Nijenhuis Robbert J. , Hoogeveen Romhild M. , de Haan Michiel W. , van Engelshoven Jos M.A. , Leiner Tim
Published: December 2004

Purpose

To investigate if the use of parallel imaging is feasible and beneficial for peripheral contrast‐enhanced magnetic resonance angiography (CE‐MRA).

Materials and Methods

A total of 19 consecutive patients underwent peripheral CE‐MRA using SENSE with two‐fold reduction in the upper and lower leg stations. Conventional nonaccelerated imaging using constant level appearance (CLEAR) was used in the aortoiliac station. The findings were compared with those in a similar patient group that underwent peripheral CE‐MR angiography using our standard imaging protocol without SENSE. Intraarterial digital subtraction angiography (IA‐DSA) was used as the standard of reference. Lower extremity vessels were divided into anatomic segments (aortoiliac, upper legs, lower legs) for review. In each anatomic segment signal‐ and contrast‐to‐noise ratios (SNR, CNR), venous contamination, subjective image quality, as well as sensitivity and specificity, were determined for both patient groups.

Results

SNR and CNR improved significantly for the aortoiliac and upper leg segments (all P‐values ≤ 0.001). Small reductions were seen in the frequency of disturbing venous enhancement (P = not significant). There were no significant differences with regards to subjective image quality or diagnostic accuracy (all P > 0.3). Overall sensitivity and specificity in the SENSE group were 81% and 95%, respectively. For the non‐SENSE group, these values were 79% and 96%, respectively.

Conclusion

Preliminary results show that three‐station peripheral CE‐MRA using a full length peripheral arterial coil in combination with SENSE in the upper and lower leg stations is feasible and useful for further optimization of peripheral MRA. Using SENSE allows for routine, high‐quality depiction of the entire peripheral vascular tree including the pedal arch. Higher SENSE factors are needed for further optimization. J. Magn. Reson. Imaging 2005;21:37–45. © 2004 Wiley‐Liss, Inc.
1‐MCP does not improve the shelf‐life of Chinese cabbage
Authors: Porter Kerry L , Collins Graham , Klieber Andreas
Published: December 2004

Chinese cabbages cv ‘Yuki’ (Brassica campestris L ssp pekinensis (Lour) Olsson) were treated with air containing 1‐methylcyclopropene (1‐MCP) at concentrations ranging from 0 to 1 µl l−1 for 12 h at 22°C before storage for 9 weeks at 3°C. Quality, weight loss and trimming loss were measured before treatment, and before and after storage, but were not influenced by 1‐MCP. 1‐MCP at 0.1 and 1.0 µl l−1 elicited increased levels of respiration and ethylene production which subsided when the cabbages were placed in cold storage. Copyright © 2004 Society of Chemical Industry
Effects of contact‐dehydrating sheets on preference for fried food and deterioration of frying oil
Authors: Shimada Yoshiko , Konishi Fumiko , Iijima Kumio , Saito Katunori , Kasai Midori , Hatae Keiko
Published: December 2004

The purpose of this study was to investigate the effects of contact‐dehydrating sheets on preferences for fried food and the deterioration of frying oil. Mackerel or chicken breast were dehydrated by wrapping with the contact‐dehydrating sheets at 4°C for 1.5 h and subsequently fried at 180°C for 3 min; those were referred to as the dehydrated samples. The same fried materials not wrapped with the contact‐dehydrating sheets were referred to as the control. The frying procedure was repeated 15 times under the above conditions and the amount of frying oil was adjusted to 1000 g by addition of new oil each time. Sensory analysis showed that the dehydrated samples were preferred to the control. Acidic values, anisidine values and ΔE values of the frying oil used for the dehydrated mackerel were significantly lower than for that used for preparing the control. These results indicate that the use of contact‐dehydrating sheets for the dehydration of the frying materials was effective in both significantly increased preference for the fried food and the retardation of the deterioration of the frying oil. Copyright © 2004 Society of Chemical Industry
Effects of conventional boiling on the polyphenols and cell walls of pears
Authors: Renard Catherine MGC
Published: December 2004

Pears of the cultivar Gieser Wildeman were cooked for up to 24 h and changes in polyphenol and cell wall components were monitored. The main polyphenols were flavan‐3‐ols (epicatechin and its procyanidin oligomers), with an average degree of polymerisation of 6, and caffeoylquinic acid. Upon cooking, flavan‐3‐ols were retained in the pear tissue while the hydroxycinnamic acids were partially leached into the cooking water. After 1 h of cooking, 65% of the original flavan‐3‐ols and 40% of the original caffeoylquinic acid were still detectable in the pear tissue; the cooking water contained only 2% of the flavan‐3‐ols but 24% of the caffeoylquinic acid. Cell walls represented 23 g kg−1 of the fresh pear and were composed of cellulose, pectins and xylans. The pectic fractions was degraded during cooking while xylans and cellulose were not affected. Copyright © 2004 Society of Chemical Industry
Treatment efficacy research: A window into genetic and neurodevelopmental correlates of developmental disabilities
Authors: Camarata Stephen M. , Wertz Robert T.
Published: December 2004

This issue of MRDD research reviews is dedicated to treatment efficacy research. The treatment of MRDD conditions has long been a central question, but the clinical science of treatment efficacy has not yet been systematically applied to many MRDD typologies. The purpose of this paper is to provide an overview of this special issue and to provide a rationale for including treatment efficacy research as a tool for studying selected neurological development and genetic correlates of MRDD. Existing treatment efficacy paradigms should be applied systematically to relevant populations (and theoretical questions) and new, objectively tested paradigms should be developed in order to integrate ongoing discovery in MRDD. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:159–161.
The catalytic role of polyaniline salt in coumarins synthesis
Authors: Palaniappan S. , Saravanan C. , Rao V. J.
Published: December 2004

Polyaniline‐sulfate salt acts as a simple and powerful polymer‐supported acid catalyst in the condensation of phenolic compounds and β‐keto esters into coumarin derivatives by a thermal heating process. This process is being reported for the first time. The catalytic use of polyaniline salt is quite feasible because of its easy preparation, activity, recovery, recyclability, stability and eco‐friendliness of the catalyst. Copyright © 2004 John Wiley & Sons, Ltd.
A study on the synthesis, characterization and properties of polyaniline using acrylic acid as a primary dopant. I: polymerization and polymer
Authors: Yang Yongsheng , Yang Wantai
Published: December 2004

In the presence of acrylic acid (AA) as a primary dopant, polyaniline (PANI) doped with poly(acrylic acid) was successfully synthesized by using ammonium persulfate (APS) as initiator and oxidizing agent. The effect of experimental conditions on the polymer yields was systematically studied. It was found that the polymer yield can be as high as 65%, and this value strongly depends on synthesis conditions, such as the reaction time, the molar ratio of oxidizing agent to aniline monomer, the concentration of reactants and reaction temperature. The molecular weight ($\bar M_{\rm w}$) of main chains of the de‐doped PANI is estimated to be 32,000–53,000. Based on the data of FT‐IR, UV‐vis, 13C‐nuclear magnetic resonance (NMR), elemental analysis and electrical conductivity measurement, the emeraldine salt form of PANI was confirmed and the molecular structure of the resulting PANI‐AA was proposed. Accordingly the reaction mechanism was discussed and it was convinced that the polymerization reaction of AA is initiated by APS. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation and characters of hyperbranched polyester‐based organic‐inorganic hybrid material compared with linear polyester
Authors: Zou Jianhua , Zhao Yongbin , Shi Wenfang , Shen Xiaofeng , Nie Kangming
Published: December 2004

To compare the properties of hyperbranched polymers with linear oligomers for preparing organic‐inorganic hybrids, hyperbranched aliphatic polyester (BoltornTM H20) and linear polyester hexa‐acrylate (EB830) were selected as organic components for preparing UV‐curable transparent hybrid materials using 3‐(trimethoxysilyl) propylmethacrylate as a coupling agent via a sol‐gel process. The prehydrolyzed product of tetraethoxysilane was used as an inorganic component. The effects of inorganic content on the morphologies, thermal behaviors, photopolymerizaiton kinetics and mechanical properties of the hybrids were investigated. The results show that for hyperbranched polyester‐based hybrids, the organic phase shows much better compatibility with inorganic phase even at high inorganic component content due to its special spheral shape and plenty of functional end groups, compared with linear EB830‐based hybrids. Copyright © 2004 John Wiley & Sons, Ltd.
Novel preparative method for porous hydrogels using overrun process
Authors: Kang Hyun Goo , Lee Sang Bong , Lee Young Moo
Published: December 2004

Porous poly(vinyl alcohol) (PVA) hydrogels were prepared using the overrun process which is usually used in manufacturing ice cream. The pores in the hydrogel formed exhibit dual‐pore structure due to the injection of air bubbles and ice recrystallization. Morphological investigation revealed that overrun‐processed hydrogels had closed pore structures and that their pore size and size distribution had been influenced by the impeller rate and concentration of polymer solution. The closed‐pore structure was reformed into interconnected open‐pore structure at lower concentrations of the solution. The freeze–thawing process, which takes place in PVA cross‐linking, has no effect on the bubble structure, but removes the small pores formed during ice recrystallization. Besides the swelling ratio of overrun‐processed PVA hydrogels is increased tenfold in comparison with non‐porous hydrogels. Overrun‐processed hydrogels showed more rapid swelling kinetics than freeze‐dried and film‐like hydrogels due to their larger surface area. In the future, the overrun process can be applied to prepare porous scaffolds containing proteins, such as growth factors and other cytokines, without denaturation, because it operates at a low temperature. Copyright © 2004 Society of Chemical Industry
Synthesis of poly(2‐vinyl pyridine)‐b‐poly(n‐hexyl isocyanate) amphiphilic coil‐rod block copolymer by anionic polymerization
Authors: Shin Yeong‐Deuk , Han Sang‐Ho , Samal Shashadhar , Lee Jae‐Suk
Published: December 2004

A well‐defined amphiphilic coil‐rod block copolymer, poly(2‐vinyl pyridine)‐b‐poly(n‐hexyl isocyanate) (P2VP‐b‐PHIC), was synthesized with quantitative yields by anionic polymerization. A low reactive one‐directional initiator, potassium diphenyl methane (DPM‐K), was very effective in polymerizing 2‐vinyl pyridine (2VP) without side reactions, leading to perfect control over molecular weight and molecular weight distribution over a broad range of initiator and monomer concentration. Copolymerization of 2VP with n‐hexyl isocyanate (HIC) was carried out in the presence of sodium tetraphenyl borate (NaBPh4) to prevent backbiting reactions during isocyanate polymerization. Terminating the living end with a suitable end‐capping agent resulted in a P2VP‐b‐PHIC coil‐rod block copolymer with controlled molecular weight and narrow molecular weight distribution. Cast film from a chloroform solution of P2VP‐b‐PHIC displayed microphase separation, characteristic of coil‐rod block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 607–615, 2005
Photografting of polymers onto nanosized silica surface initiated by eosin moieties immobilized onto the surface
Authors: Satoh Masayoshi , Shirai Kumi , Saitoh Hiroshi , Yamauchi Takeshi , Tsubokawa Norio
Published: December 2004

The photograft polymerization of various vinyl monomers onto nanosized silica surfaces was investigated. It was initiated by eosin moieties introduced onto the silica surface. The preparation of the silica with eosin moieties was achieved by the reaction of eosin with benzyl chloride groups on the silica surface.These were introduced by the reaction of surface silanol groups with 4‐(chloromethyl)phenyltrimethoxysilane in the presence of t‐butyl ammonium bromide as a phase‐transfer catalyst. The photopolymerization of various vinyl monomers, such as styrene, acrylamide, acrylic acid, and acrylonitrile was successfully initiated by eosin moieties on the silica surface in the presence of ascorbic acid as a reducing agent and by oxygen. The corresponding polymers were grafted from the silica surface. The grafting efficiency (percentage of grafted polymer to total polymer formed) in the photoinitiation system was much larger than that in the radical polymerization initiated by surface radicals; these radicals were formed by the thermal decomposition of azo groups introduced onto the silica surface. It was found that the polymer‐grafted silica gave stable dispersions in good solvents of grafted polymer and the wettability of the surfaces can be easily controlled by grafting of polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 600–606, 2005
Three‐component negative‐type photosensitive polyimide precursor based on poly(amic acid), a crosslinker, and a photoacid generator
Authors: Watanabe Yasufumi , Fukukawa Ken‐ichi , Shibasaki Yuji , Ueda Mitsuru
Published: December 2004

A new negative‐working and alkaline‐developable photosensitive polyimide precursor based on poly(amic acid) (PAA), 4,4′‐methylenebis[2,6‐bis(hydroxymethyl)]phenol (MBHP) as a crosslinker, and a photoacid generator (5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐2‐(methylphenyl)acetonitrile (PTMA) has been developed. PAA was prepared by ring‐opening polymerization of pyromellitic dianhydride with 4,4′‐oxydianiline. The photosensitive polyimide precursor containing PAA (65 wt %), MBHP (25 wt %), and PTMA (10 wt %) showed a clear negative image featuring 10 μm line and space patterns when it was exposed to 436 nm light at 100 mJ·cm−2, post‐exposure baked at 130 °C for 3 min, followed by developing with a 2.38 wt % aqueous tetramethylammonium hydroxide solution at 25 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 593–599, 2005
Synthesis of a pyrrole‐based methine bridge type liquid‐crystalline conjugated polymer
Authors: Goto Hiromasa , Akagi Kazuo
Published: December 2004

Conjugated polymers consisting of pyrrole or an N‐substituted pyrrole bridged by methine with a mesogenic group were synthesized. Chemical structures of the products were confirmed with IR, NMR, UV–visible (UV–vis) spectroscopy, and gel permeation chromatography analysis. Liquid crystallinity was examined with differential scanning calorimetry measurements and polarizing optical microscopy observations. Liquid crystal domains of the polymer were macroscopically oriented in one direction by an external magnetic force (10 Tesla). The polymer orientation was confirmed by optical microscopy and X‐ray analysis. One of the polymers exhibited a striated fan‐shaped texture when observed with a polarizing optical microscope. This is attributed to the formation of a chiral smectic C (SmC*) phase, which is a property of ferroelectricity. Spontaneous polarization of the polymer occurred at 110 nC/cm2. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 616–629, 2005
Study of the spectroscopic properties and infrared‐to‐visible up‐conversion fluorescence of Er3+‐doped germanate glasses
Authors: Ajroud M. , Haouari M. , Ben Ouada H. , Mâaref H. , Brenier A. , Champagnon B.
Published: December 2004

Raman scattering, optical absorption and photoluminescence studies have been performed on Er3+‐doped Na2O–Nb2O5–GeO2 germanate‐based glasses. The main bands in the Raman spectra involve vibrational modes associated with the germanium oxide network. Judd–Ofelt intensity parameters were determined and then used to calculate the radiative transition rates and excited‐state radiative lifetimes. Green and red up‐conversion luminescence was observed at room temperature under 800 nm laser line excitation. The emission intensities have a quadratic dependence on the excitation pump power, indicating a two‐step up‐conversion mechanism. The intensity of the 660 nm red band shows an increase relative to the 554 nm green band with increasing Er3+ content. Combined with the time‐resolved luminescence data of the emitting states, we suggest from these results that the up‐conversion process is attributed to a competitive situation of excited‐state absorption and energy transfer between excited ions accompanied by multiphonon relaxation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic evolution of software processes to evolve software systems during their development
Authors: Beydeda Sami , Gruhn Volker
Published: December 2004

A software system, once deployed into its target environment, might need to be modified for various reasons. The reasons might be specific to that software system, such as failures, or, more general, such as changes in the environment in which the software system is embedded. Depending on the reason, a modification might obviously not only be restricted to a particular software system. It might also concern other existing software systems and particularly also software systems under development.

The modification of a software system under development is merely a problem of modifying its development process, also called software process. Such modifications generally cannot be automatically carried out by autonomous process support systems due to the complexity inherent in software processes and in the necessary modifications. It usually needs to be guided by a human process manager. A process support system can, however, offer the human process manager certain services to assist in modifying a software process. One of these services is that of decision support.

This article describes a decision support system developed in the ESPRIT project Process Instance Evolution (PIE). One of the features of the decision support system is an extendable database of decision models, each of which is capable of generating specific information to assist the process manager. One of these models is that of risk analysis. Risk analysis, as used in this context, encompasses assessment of the impact of a possible modification on certain software process attributes before actually changing a software process. Copyright © 2004 John Wiley & Sons, Ltd.
Electron probe microanalysis (EPMA) measurement of aluminum oxide film thickness in the nanometer range on aluminum sheets
Authors: Osada Yoshio
Published: December 2004

By using Monte Carlo simulation, the thickness of an aluminum oxide film in the nanometer range on aluminum sheets given different heat treatments was determined by electron probe microanalysis (EPMA) and compared with transmission electron microscopy (TEM). The film thickness was ≤50 nm. As a result, although the same analysis areas were not measured, similar deviations between EPMA and TEM were found. Consequently, we found that the Monte Carlo method was useful for measuring the oxide film thickness in the nanometer range on aluminum sheets. Copyright © 2004 John Wiley & Sons, Ltd.
Facies and depositional sequence evolution controlled by high-frequency sea-level changes in a shallow-water carbonate ramp (late Kimmeridgian, NE Spain)
Authors: AURELL M. , BÁDENAS B.
Published: December 2004

The outcrops of the Sierra de Albarracín (NE Spain) allow a precise reconstruction of the shallow sedimentary domains of a late Kimmeridgian carbonate ramp, developed in western marginal areas of the Iberian Basin. The sedimentary record shows a hierarchical sequence stratigraphic organization, which implies sea-level changes of different frequencies. The studied succession is arranged in a long-term transgressive–regressive sequence, which is likely to reflect local variation in the subsidence rates. This sequence includes four higher-order sequences A to D, which have variable thickness (from 3 to 21 m). The similar sedimentary evolution observed in distant localities suggests the existence of high-frequency sea-level fluctuations controlling the sequence development. The average amplitude of these cycles would range from 5 to 10 m. The precise estimation of their duration (some few hundreds of kyr) and their possible assignment to any of the long-term orbital cycles (the 100 or the 400 kyr eccentricity cycles) is uncertain. Sequences A and B, formed during the long-term transgressive interval, are relatively thin (from 3 to 9 m) give-up sequences that were never subaerially exposed. These sequences are locally formed by five shallowing-upward elementary sequences. Sequences C and D are catch-down sequences with evidence of emersion of subtidal facies. Sequence C, formed during the stage of maximum gain of long-term accommodation, is the thickest sequence (from 13 to 21 m) and includes coral–microbial reefs (pinnacles up to 16 m in height). The increased production rates were able to fill part of the accommodation created during the early stage of high-frequency sea-level rise and the shallow platform was eventually exposed to subaereal erosion and meteoric cementation.
Fracture prediction for the 1980 El Asnam, Algeria earthquake via elastic dislocation modeling
Authors: Healy David , Yielding Graham , Kusznir Nick
Published: December 2004

Geomechanical models based on linear elasticity have been used to predict the mode and distribution of subseismic fractures around larger faults. These models can be tested against field observations of surface breaks (fractures) formed in the aftermath of large earthquakes. This paper presents forward models based on elastic dislocation theory of the deformation due to the Ms 7.3 earthquake at El Asnam, Algeria in 1980. Using fault parameters from previous geodetic studies to define a set of larger faults, our models calculate the deformation field in the surrounding rock volume. We compare predicted strain and stress fields with the surface deformation measured in the area following the 1980 earthquake. Using a combination of the redistributed elastic dislocation stress due to slip on the major faults and a small component of overburden stress, the models successfully predict normal faults and tensile fractures in the hanging wall of the reverse fault system. Orientations of the predicted faults vary along strike of the fault system, being parallel to the main reverse fault in the south but oblique to it along the central segment, agreeing with observed surface breaks. The results of our forward modeling are not sensitive to the magnitude or direction of a regional tectonic stress. The predicted fractures are controlled by the near‐field, short‐term redistributed stresses due to coseismic slip. The agreement between modeled and measured deformation patterns adds confidence in the use of elastic dislocation theory to accurately predict small faults generated by coseismic slip on large faults.
Toward a conceptual model of floodplain water table response
Authors: Jung M. , Burt T. P. , Bates P. D.
Published: December 2004

Hydrological processes operating within floodplains in temperate midlatitudes have significant implications for water management by controlling pollutant transfer between the catchment and the fluvial system. However, there is a lack of relevant high‐resolution data from which the dynamics of floodplain hydrology during flood events can be inferred. A detailed analysis of water table fluctuations during flood events within a typical European lowland floodplain system (River Severn, United Kingdom) is presented. Data collected hourly along two 120‐meter‐long transects, each comprising four piezometers, plus one river stage sensor, are analyzed for the winter season 1998–1999 using correlation analysis, hysteresis curves, and water table maps. The objective is to develop a conceptual model that provides mechanistic understanding of floodplain water table response during flood events. River stage is shown to be the principal driver of water table fluctuations. Piezometers with similar water table response are identified; their consistent pattern of response in different flood events is attributed to sedimentary and morphological controls on the floodplain and adjoining hillslopes. Deviations from the general pattern are a function of low antecedent soil moisture, which is only a significant factor at the beginning of the winter season, when the floodplain is initially dry. Our conceptual model adopts a kinematic wave process whereby river stage change induces rapid responses of the water table over many tens of meters across the floodplain, associated with flux velocities several orders of magnitude higher than would be expected for Darcian flow. The occurrence of a groundwater ridge within the floodplain dams hillslope drainage and causes the water table to rise at the back of the floodplain. The disappearance of the groundwater ridge during the recession reestablishes hillslope flow into the floodplain, resulting in significant three‐dimensional hydraulic gradients directed both perpendicular and parallel to the channel axis.
Amplitude variations in GPS signals as a possible indicator of ionospheric structures
Authors: Wickert J. , Pavelyev A. G. , Liou Y. A. , Schmidt T. , Reigber C. , Igarashi K. , Pavelyev A. A. , Matyugov S.
Published: December 2004

The noisy and impulsive fluctuations in the CHAMP radio occultation (RO) amplitude data are similar to the C‐type and S‐type ionospheric amplitude scintillations formerly observed at 1.5 GHz in the mid‐latitude region in satellite‐to‐Earth Inmarsat links. These amplitude scintillations can be associated with different types of ionospheric structures. S‐type amplitude variations can be explained by the influence of inclined plasma layers in the ionosphere where the RO signal trajectory is perpendicular to the sharp plasma gradient. Simulation indicates the possibility to reveal the spatial distribution of the electron density in the inclined ionospheric layers from analysis of the S‐type RO amplitude variations. The seasonal, geographical and temporal distributions of CHAMP RO events with high S4 index values observed during the years 2001–2003 indicate their dependence on solar activity.
Distribution of dissolved organic matter in the eastern Bering Sea, Chukchi Sea (Barrow Canyon) and Beaufort Sea
Authors: Shin Kyung‐Hoon , Tanaka Noriyuki
Published: December 2004

The distribution of dissolved organic carbon (DOC) in the western Arctic Ocean is greatly influenced by conservative riverine DOC flux into the northern Bering Sea, Bering Strait and Beaufort Sea, as indicated by an inverse correlation with salinity. Based on the relations between DOC, salinity and seawater temperature, several water masses could be identified. These included riverine water, ice‐melt water, surface mixed water, cold and saline shelf water, and Atlantic Ocean water. High concentrations of chlorophyll a and DOC were found in some parcels of dense shelf water in Barrow Canyon. In addition, labile DOC compounds, such as polyunsaturated fatty acids (PUFA), were found in the dense shelf water, suggesting the dense shelf water contains a product (marine organic matter) of the biological CO2 pump.
Underestimated tropical stratiform precipitation in the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM3)
Authors: Song Xiaoliang , Yu Rucong
Published: December 2004

The ratio between stratiform and convective precipitation simulated by the NCAR CCM3 is examined. Stratiform rain only accounts for about 1.5% of the total rain amount in CCM3 between 20°N and 20°S, far lower than 40% estimated from Tropical Rainfall Measuring Mission (TRMM) data. Preliminary study suggests that the serious underestimation of stratiform precipitation in CCM3 could be responsible for failed simulations of intraseasonal oscillation (ISO) and seasonal migration of the intertropical convergence zone (ITCZ) precipitation across the equator. Sensitivity experiment with artificially enhanced stratiform precipitation indicates that increase of stratiform rain fraction can improve the simulations of ISO and seasonal migration of the ITCZ precipitation. This study suggests that reasonable partition of stratiform and convective precipitation is crucial for a climate model to project realistic climate features.
Quantifying ice‐sheet feedbacks during the last glacial inception
Authors: Kageyama M. , Charbit S. , Ritz C. , Khodri M. , Ramstein G.
Published: December 2004

The last glacial inception (∼116 ky ago) has long been used to test the sensitivity of climate models to insolation. From these simulations, atmospheric, oceanic and vegetation feedbacks have been shown to amplify the initial insolation signal into a rapid growth of ice‐sheets over the northern hemisphere. However, due to the lack of comprehensive atmosphere‐ocean‐vegetation‐northern hemisphere ice‐sheet models, the impact of all these feedbacks acting concurrently has not yet been evaluated. Here we present the results from such a model, which simulates significant ice‐sheet growth over North America, but none over Eurasia. Our analyses focus on the different behaviours over these regions, and the quantification of the ice‐sheet feedbacks on climate.
On the occurrence and spatial extent of electron precipitation induced by oblique nonducted whistler waves
Authors: Peter W. B. , Inan U. S.
Published: December 2004

Two different 4‐hour sequences of subionospheric Very Low Frequency (VLF) signal perturbations are examined to characterize electron precipitation induced by nonducted obliquely propagating whistlers. These lightning‐induced electron precipitation (LEP) events are typically associated with cloud‐to‐ground lightning discharges. The temporal and spatial signatures of LEP events associated with two disparate storms occurring over two 4‐hour periods are examined. A distributed set of VLF observing sites, known as the Holographic Array for Ionospheric and Lightning Research (HAIL), captures the full latitudinal extent of the events, providing evidence that 90% of the precipitation occurs over a region 8° ± 1° and 9° ± 1° in latitudinal extent for the two time periods. The measured peak of the precipitation is poleward displaced (6°45′ ± 30′ and 7°45′ ± 30′ for the two case studies) from the causative discharge. Analysis indicates that the onset delay and the duration of precipitation steadily increase with increasing L‐value, while the signal recovery time is independent of L‐value for the LEP events associated with both storms. The causative lightning discharges associated with the two storms were located at different latitudes. For lightning occurring in the storm at higher latitudes, the associated LEP events are of longer duration and exhibit precipitation in a smaller area displaced less from the causative discharge. The onset delays and event durations increase more rapidly with increasing L‐value for events associated with lightning occurring in the storm at higher latitudes. The general spatial and temporal signatures are consistent with those expected for LEP events induced by nonducted whistlers.
A new look at driven magnetic reconnection at the terrestrial subsolar magnetopause
Authors: Dorelli John C. , Hesse Michael , Kuznetsova Maria M. , Rastaetter Lutz , Raeder Joachim
Published: December 2004

The physics of steady driven magnetic reconnection at Earth's subsolar magnetopause is addressed. Three‐dimensional, global magnetohydrodynamics (MHD) simulations of the magnetopause are compared with analytical solutions of the resistive MHD equations [Sonnerup and Priest, 1975] corresponding to magnetic field annihilation driven by an incompressible stagnation point flow. The simulations demonstrate that under steady southward interplanetary magnetic field conditions and when the plasma resistivity is spatially uniform, subsolar magnetopause reconnection occurs in long, thin Sweet‐Parker current sheets via a flux pileup mechanism [Sonnerup and Priest, 1975; Priest and Forbes, 1986] (rather than in Petschek slow shock configurations). Magnetic energy piles up upstream of the magnetopause current sheet to accommodate the sub‐Alfvénic solar wind inflow. The scaling of the pileup with Lundquist number, S, is consistent (approximately ∝ S1/4) with that predicted by the analytical, incompressible stagnation point flow solutions (though there are small corrections due to plasma compressibility in the simulations). Since there is a finite energy in the magnetosheath available to drive the magnetic pileup (and associated rapid magnetic reconnection), we expect the pileup to saturate and the reconnection rate to drop as the upstream plasma pressure drops to accommodate the pileup. Thus we expect the reconnection to stall, the rate vanishing in the limit S → ∞. We discuss the role of Hall electric fields in allowing the magnetic pileup to saturate before the reconnection begins to stall, permitting Alfvénic reconnection to occur in thin current sheets in the limit S → ∞.
Evidence of jovian active longitude: 1. Efficiency of cyclotron maser instability
Authors: Galopeau Patrick H. M. , Boudjada Mohammed Y. , Rucker Helmut O.
Published: December 2004

Long‐term observations of Jupiter's decametric radiation have shown that a great part of emission is modulated by two dominant factors: the planetary rotation and the orbital phase of Io. The first one indicates that the occurrence probability of the radiation depends on the observer's longitude, while the second factor points to a control of part of the radio emission by Io. Within the framework of the cyclotron maser instability, which is supposed to be the mechanism at the origin of most planetary radio emissions, we estimate the efficiency of this theoretical mechanism at the footprint of the Io flux tube during a complete revolution of the satellite around Jupiter. Our study is based on several simplifying hypotheses: on one hand, we suppose that electrons are accelerated in the neighborhood of Io and follow an adiabatic motion along magnetic field lines carried by the satellite; on the other hand, we assume that a loss cone built up by electrons which have disappeared in Jupiter's ionosphere constitutes the main source of free energy needed by the cyclotron maser instability to produce the radiation. We calculate the maximum growth rate of the waves amplified by the mechanism as a function of the jovicentric longitude of Io. It emerges that some longitudes in the Northern and Southern Hemispheres favor the radio decametric emission and lead to a higher occurrence probability. Our results are compared to the occurrences observed for the sources Io‐A, Io‐B, Io‐C, and Io‐D in the usual central meridian longitude‐Io phase diagram.
Eocene circulation of the Southern Ocean: Was Antarctica kept warm by subtropical waters?
Authors: Huber Matthew , Brinkhuis Henk , Stickley Catherine E. , Döös Kristofer , Sluijs Appy , Warnaar Jeroen , Schellenberg Stephen A. , Williams Graham L.
Published: December 2004

Near the Eocene's close (∼34 million years ago), the climate system underwent one of the largest shifts in Earth's history: Antarctic terrestrial ice sheets suddenly grew and ocean productivity patterns changed. Previous studies conjectured that poleward penetration of warm, subtropical currents, the East Australian Current (EAC) in particular, caused Eocene Antarctic warmth. Late Eocene opening of an ocean gateway between Australia and Antarctica was conjectured to have disrupted the EAC, cooled Antarctica, and allowed ice sheets to develop. Here we reconstruct Eocene paleoceanographic circulation in the Tasmanian region, using (1) biogeographical distributions of phytoplankton, including data from recently drilled Ocean Drilling Program Leg 189 sites and (2) fully coupled climate model simulations. We find that the EAC did not penetrate to high latitudes and ocean heat transport in the region was not greater than modern. Our results do not support changes in “thermal isolation” as the primary driver of the Eocene‐Oligocene climatic transition.
Timing and nature of the deepening of the Tasmanian Gateway
Authors: Stickley Catherine E. , Brinkhuis Henk , Schellenberg Stephen A. , Sluijs Appy , Röhl Ursula , Fuller Michael , Grauert Marianne , Huber Matthew , Warnaar Jeroen , Williams Graham L.
Published: December 2004

Tectonic changes that produced a deep Tasmanian Gateway between Australia and Antarctica are widely invoked as the major mechanism for Antarctic cryosphere growth and Antarctic Circumpolar Current (ACC) development during the Eocene/Oligocene (E/O) transition (∼34–33 Ma). Ocean Drilling Program (ODP) Leg 189 recovered near‐continuous marine sedimentary records across the E/O transition interval at four sites around Tasmania. These records are largely barren of calcareous microfossils but contain a rich record of siliceous‐ and organic‐walled marine microfossils. In this study we integrate micropaleontological, sedimentological, geochemical, and paleomagnetic data from Site 1172 (East Tasman Plateau) to identify four distinct phases (A–D) in the E/O Tasmanian Gateway deepening that are correlative among ODP Leg 189 sites. Phase A, prior to ∼35.5 Ma: minor initial deepening characterized by a shallow marine prodeltaic setting with initial condensation episodes. Phase B, ∼35.5–33.5 Ma: increased deepening marked by the onset of major glauconitic deposition and inception of energetic bottom‐water currents. Phase C, ∼33.5–30.2 Ma: further deepening to bathyal depths, with episodic erosion by increasingly energetic bottom‐water currents. Phase D, <30.2 Ma: establishment of stable, open‐ocean, warm‐temperate, oligotrophic settings characterized by siliceous‐carbonate ooze deposition. Our combined evidence indicates that this early Oligocene Tasmanian Gateway deepening initially produced an eastward flow of relatively warm surface waters from the Australo‐Antarctic Gulf into the southwestern Pacific Ocean. This “proto‐Leeuwin” current fundamentally differs from previous regional reconstructions of eastward flowing cool water (e.g., a “proto‐ACC”) during the early Oligocene and thereby represents an important new constraint for reconstructing regional‐ to global‐scale dynamics for this major global change event.
Oxygen isotopic composition of Globorotalia truncatulinoides as a proxy for intermediate depth density
Authors: LeGrande Allegra N. , Lynch‐Stieglitz Jean , Farmer Emma C.
Published: December 2004

We investigate whether the oxygen isotope ratio in the test of Globorotalia truncatulinoides can serve as a proxy for intermediate depth (200–500 m) density. Since intermediate depth horizontal density gradients are associated with the vertical shear of upper ocean flows, this proxy could provide a tool for reconstructing past ocean circulation. The spatial pattern of core top Gr. truncatulinoides δ18O in the Atlantic Ocean mimics the upper ocean density gradients associated with the major ocean currents. To better constrain the controls on the calcification depth(s) of Gr. truncatulinoides, we attempt to simulate the surface sediment data set using water column temperature and salinity conditions above the core sites. We predicted foraminiferal δ18O for each core site assuming (1) the calcification occurs at a single depth and (2) the initial calcification is at the surface and the subsequent calcification is at 800 m water depth. The predicted δ18O best resembles measured δ18O of Gr. truncatulinoides when using (1) a single depth calcification at 350 m or (2) a two‐depth approximation with 30% surface and 70% 800‐m calcification. This result gives us confidence in the ability of δ18O in Gr. truncatulinoides to proxy lateral density gradients at the intermediate depths associated with upper ocean flow.
Relationships between spectral optical properties and optically active substances in a clear oligotrophic lake
Authors: Belzile Claude , Vincent Warwick F. , Howard‐Williams Clive , Hawes Ian , James Mark R. , Kumagai Michio , Roesler Collin S.
Published: December 2004

The absorption and scattering coefficients in the euphotic zone of oligotrophic Lake Taupo, New Zealand, were measured at 19 stations across the 620 km2 lake in late fall during the period of mixed layer deepening and development of the annual phytoplankton maximum. These coefficients were subsequently related to the water content of colored dissolved organic matter (CDOM), phytoplankton, and nonalgal particles via measurements of the absorption spectra of these optically active substances and of chlorophyll a and suspended particle concentrations. Measurements of the spectral diffuse attenuation coefficient for downwelling irradiance (Kd) and of reflectance (Lu/Ed) revealed that the clear blue waters of Lake Taupo had a minimum Kd of 0.09 m−1 at 500 nm and maximum reflectance at 490 nm. The measured Kd and Lu/Ed were well described by modeled spectra that were computed using a radiative transfer model (Hydrolight) assuming relatively low values for the backscattering ratio (0.008–0.014). The relationships established here between the optical properties and optically active substances were consistent with previous observations in case 2 marine waters, and they will provide a basis for prediction of eutrophication, climate, and other environmental effects on the blueness and transparency of large oligotrophic lakes.
Simulating soil water dynamics in a cutover bog
Authors: Kennedy G. W. , Price J. S.
Published: December 2004

A simulation model flow in cutover peat systems (FLOCOPS) was developed to improve the current understanding of the hydrology of cutover peatlands and the water management programs designed to restore them. FLOCOPS considers temporal variability in peat bulk density, shrinkage character and θ‐Ψ (soil moisture–pressure head) relationships, volume changes due to compression, and changes to saturated hydraulic conductivity (KS) and saturated volumetric soil moisture (θS). FLOCOPS was evaluated by comparing simulated and observed 1998–1999 trends in elevation change (thickness of peat deposit), water table, θ, and Ψ. FLOCOPS effectively represented observed trends in elevation change, θ, and Ψ. A sensitivity analysis indicated that FLOCOPS was most sensitive to the retention, storage, and consolidation characteristics of the peat. Volume changes reduced hydrological variability, whereas low water retentivity and high water storage helped maintain high and stable θ, Ψ, and water table position. The sensitivity of the peat system's hydrology to changes in pore structure suggests that minimizing changes to the peat's characteristic pore structure during extraction and subsequent abandonment of the peatland will result in significantly more favorable hydrological conditions for bog restoration.
Frequency analysis via copulas: Theoretical aspects and applications to hydrological events
Authors: Salvadori G. , De Michele C.
Published: December 2004

In this paper we provide a general theoretical framework exploiting copulas for studying the return periods of hydrological events; in particular, we consider events depending upon the joint behavior of two nonindependent random variables, an approach which can easily be generalized to the multivariate case. We show that using copulas may greatly simplify the calculations and may even yield analytical expressions for the isolines of the return periods, both in the unconditional and in the conditional case. In addition, we show how a new probability distribution may be associated with the return period of specific events and introduce the definitions of sub‐, super‐, and critical events as well as those of primary and secondary return periods. An illustration of the techniques proposed is provided by analyzing some case studies already examined in literature.
Bayesian identification of the local transmissivity using time‐drawdown data from pumping tests
Authors: Copty Nadim K. , Findikakis Angelos N.
Published: December 2004

Conventional pumping test analysis techniques focus mostly on estimating the effective transmissivity of the perturbed subsurface volume surrounding the extraction and observation wells, ignoring the existing local‐scale heterogeneity. The purpose of this paper is to explore whether transient drawdown data derived from pumping tests can also be used to identify the statistical spatial structure of the local transmissivity field. The log‐transmissivity is modeled as a multivariate random spatial function with stationary mean, and exponential semivariogram. Monte Carlo simulations are used to compute the transient drawdown for different values of the log‐transmissivity variance and integral scale. On the basis of these simulations, a Bayesian procedure is developed to estimate the probability density functions of these two statistical parameters. The main benefit of using a Bayesian approach is that it readily accounts for the uncertainty of the estimated parameters. Application of the proposed procedure to simulated drawdown data shows that it is possible to characterize the local transmissivity from pumping test data and that the reliability of the estimates increases with an increase in the number of available tests.