bluuebunny/crossref_metadata_2025 huggingface dataset:
MR assessment of left ventricular function: Quantitative comparison of fast imaging employing steady‐state acquisition (FIESTA) with fast gradient echo cine technique
Authors: Li Wei , Stern Jessica S. , Mai Vu M. , Pierchala Linda N , Edelman Robert R , Prasad Pottumarthi V.
Published: November 2002

Purpose

To evaluate the agreement of fast imaging employing steady‐state acquisition (FIESTA) cine technique with segmented k‐space fast gradient echo (GRE) cine technique when using them for assessment of cardiac function.

Materials and Methods

Eleven MR cine studies were performed on six healthy volunteers and five patients, using FIESTA and fast GRE techniques. The quantitative measurements of ventricular function obtained from the two techniques were compared. The data analysis was performed by two observers independently.

Results

Compared to fast GRE cine technique, FIESTA cine technique consistently resulted in higher end‐diastolic volume (10.2%) and end‐systolic volume (21.6%), but lower myocardial mass of left ventricle (19.2%) and ejection fraction (9.9%). The stroke volume obtained from the two techniques was very close. The primary explanation for this variability is that the two techniques have different mechanisms on establishing signal contrast.

Conclusion

Compared to fast GRE technique, FIESTA provides significantly different results when using it for assessment of left ventricular function. It is important to consider this difference in the assessment of cardiac function. J. Magn. Reson. Imaging 2002;16:559–564. © 2002 Wiley‐Liss, Inc.
MR‐guided microwave thermocoagulation therapy of liver tumors: Initial clinical experiences using a 0.5 T open MR system
Authors: Morikawa Shigehiro , Inubushi Toshiro , Kurumi Yoshimasa , Naka Shigeyuki , Sato Koichiro , Tani Tohru , Yamamoto Ikuo , Fujimura Masaki
Published: November 2002

Purpose

To utilize a microwave coagulator for MR‐guided interstitial thermal therapy of liver tumors as a clinically feasible heating device.

Materials and Methods

MR‐guided microwave thermocoagulation therapy was carried out 34 times in 30 patients with liver tumors (eight hepatocellular carcinoma, 22 metastatic tumors) using a 0.5 T open configuration MR system.

Results

Percutaneous puncture could be accomplished both accurately and safely while monitoring real‐time magnetic resonance imaging (MRI). Using a notch filter, MR images could be observed without electromagnetic interference even during microwave ablation. Temperature monitoring during ablation was possible using the proton resonance frequency method. All procedures could be successfully carried out without any complications, and the therapeutic effects were deemed satisfactory.

Conclusion

MR‐guided microwave thermocoagulation therapy could be one promising procedure of minimally invasive treatment for liver tumors. J. Magn. Reson. Imaging 2002;16:576–583. © 2002 Wiley‐Liss, Inc.
Tissue thermal conductivity by magnetic resonance thermometry and focused ultrasound heating
Authors: Cheng Hai‐Ling Margaret , Plewes Donald B.
Published: November 2002

Purpose

To investigate the combined use of magnetic resonance (MR) temperature imaging and focused ultrasound (FUS) for the noninvasive determination of tissue thermal properties.

Materials and Methods

Brief, spatial impulses of temperature elevation were created in tissue using a spherical, air‐backed transducer operating at 1.68 MHz and measured using MR temperature imaging in a 1.5‐Tesla clinical scanner. A novel technique based on thermal washout is applied in an analysis of the acquired MR temperature images to estimate tissue thermal conductivity and perfusion.

Results

Numerical simulations and experiments in vitro and in vivo demonstrate that thermal conductivity can be measured to within 10% of the true value with MR thermometry at 1.5 Tesla. With the temperature precision available at 1.5 Tesla, however, robust perfusion estimation is feasible only in highly perfused organs or tumors.

Conclusion

This study has developed a method for determining tissue thermal properties specific to the patient and organ at the site of interest, and allows repeated application. This capability is relevant in thermal therapy planning of tumor ablation using MR‐guided FUS systems. J. Magn. Reson. Imaging 2002;16:598–609. © 2002 Wiley‐Liss, Inc.
Modern distribution of saltmarsh testate amoebae: regional variability of zonation and response to environmental variables
Authors: Charman Dan J. , Roe Helen M. , Roland Gehrels W.
Published: November 2002

Sea‐level reconstruction from biological indicators in saltmarsh sediments requires an understanding of the modern ecology of the organisms concerned. Previous work suggested that testate amoebae are a potential new group of organisms to use for sea‐level reconstruction, especially combined with diatoms and foraminifera. This paper analyses data from three saltmarshes on the Taf estuary, South Wales, the River Erme, Devon, and at Brancaster, Norfolk (UK) to (i) test for the presence and zonation of testate amoebae in relation to elevation; (ii) examine the similarity of zonation patterns between marshes; and (iii) explore the relationship between assemblage composition and a wider range of environmental variables. In addition we provide an update on the identification of testate amoebae on saltmarshes. Our results confirm that at all sites the primary environmental gradient is tidal inundation. Major changes in taxa along the tidal gradient are similar except for the lowest elevations, where different taxa become dominant at different sites. Canonical correspondence analysis (CCA) shows that assemblage composition is also strongly related to other variables, independent of the tidal position. Salinity, particle size and organic matter content are particularly important, and there is a statistically significant geographical effect on assemblages. Relationships between sea‐level and assemblage composition are often stronger for individual sites, suggesting that local data sets should be used for quantitative sea‐level reconstructions. However, the combined data set would provide more robust estimates of past sea‐level change from fossil data. Other environmental variables explain as much of the variability in species assemblages as tidal parameters and should be considered more often in sea‐level reconstructions based on microfossil indicators. Copyright © 2002 John Wiley & Sons, Ltd.
Fossil testate amoebae in coastal deposits in the UK: implications for studies of sea‐level change
Authors: Roe Helen M. , Charman Dan J. , Roland Gehrels W.
Published: November 2002

Assemblages of testate amoebae in UK saltmarshes are strongly correlated with elevation and flooding duration, suggesting that if adequately preserved in sediments they may be used as accurate sea‐level indicators. To examine the preservation of testate amoebae in the fossil record in coastal environments, subsamples were collected from a range of coastal sites around Britain, including saltmarsh, coastal reedswamp, isolation basin, back‐barrier and coastal raised bog sites. The results showed that testate amoebae are present in the fossil record, although in variarble species diversities, concentrations and states of preservation. Testate amoebae were found to be well preserved in isolation basin infills and coastal raised bog deposits, where diverse assemblages (>20 taxa) were recorded. In the upper part of the isolation basin sequence from Loch nan Corr, northwest Scotland, the testate amoebae assemblages showed a greater degree of sensitivity to transitional salinity changes than existing foraminferal and larger testate amoebae data sets. This implies that testate amoebae, particularly small to medium‐sized specimens (15–300 µm), may hold considerable potential for sea‐level reconstruction in these environments. Preservation of testate amoebae in a freshly sampled core of saltmarsh sediment from South Wales was reasonable, although test distribution decreased significantly in abundance below 18 cm. The assemblage composition was similar to that found in the contemporary surface environment. The preservation of testate amoebae in saltmarsh and coastal reedswamp deposits of mid‐Holocene age was variable and generally poor. Partial dehydration of the sediment samples may account for this. Further studies are required to examine the palaeoecology and distribution of testate amoebae in similar coastal settings, to strengthen these preliminary findings. Copyright © 2002 John Wiley & Sons, Ltd.
A revised chronology for the ‘Fjord Stade’ moraine in Disko Bugt, west Greenland
Authors: Long Antony J. , Roberts David H.
Published: November 2002

This paper re‐evaluates the age of the ‘Fjord Stade’ moraine in Disko Bugt, a large marine embayment in west Greenland. Previous work suggests that this moraine is part of a widespread moraine complex present throughout west Greenland, which formed ca. 9300 cal. yr BP in response to either a regional climate change or the effects of topographic controls on ice‐sheet recession. We present the results of a relative sea‐level study using data from eight isolation basins that straddle the ‘Fjord Stade’ moraine in southeast Disko Bugt. Our results suggest that the moraine here formed between ca. 8400 and 7700 cal. yr BP. This is later than previously thought, and similar in timing to a widespread cooling event recorded in the Greenland ice‐core records. This chronological similarity raises the possibility that the ‘Fjord Stade’ moraine in the study area records an ice marginal response to a major short‐lived climatic cooling during the early Holocene (the so‐called ‘8200 event’). Copyright © 2002 John Wiley & Sons, Ltd.
The marine Eemian of the Baltic: new pollen and diatom data from Peski, Russia, and Põhja‐Uhtju, Estonia
Authors: Miettinen Arto , Rinne Katja , Haila Heikki , Hyvärinen Hannu , Eronen Matti , Delusina Irina , Kadastik Ene , Kalm Volli , Gibbard Philip
Published: November 2002

Several relatively well‐preserved last interglacial (Eemian, marine oxygen isotope substage 5e; ca. 130–116 ka) deposits containing marine diatom flora have been found in Finland. In addition to these Finnish sites, more numerous Eemian (Mikulino) marine deposits are known from the northwestern part of Russia and from Estonia.

Two new clayey and silty deposits covered by till, one at Peski, Russia, and the other Põhja‐Uhtju, Estonia, were studied for pollen and diatom content. At Peski, the deposit representing the Eemian interglacial is 3.8 m thick. The polyhalobous diatom flora in the Corylus and Carpinus zones indicates the maximum of the marine transgression during the climatic optimum. Later, the increasing proportion of brackish water diatom flora indicates a lowering in the relative sea‐level, and finally, during a very late phase of the Eemian, the sharply increasing proportion of freshwater species indicates the isolation of the sedimentary basin from the Eemian Sea.

At Põhja‐Uhtju, according to the pollen, the Eemian deposit is 3.5 m thick. Diatoms occur only in a layer 1.6 m thick, which represents the period of Corylus and Carpinus zones, and thus the period of the climatic optimum. The brackish–marine diatom flora consists mainly of littoral, shallow‐water species.

Although Peski is situated at a higher altitude than Põhja‐Uhtju at present, the diatom stratigraphy at Peski indicates deeper and more saline conditions than at Põhja‐Uhtju during the Eemian. This probably is the result of variations in glacio‐isostatic rebound between these sites, which can be accounted for by differences of the ice load during the final phase of the Saalian glaciation. Copyright © 2002 John Wiley & Sons, Ltd.
Changes in coastal zone processes at a high sea‐level stand: a late Holocene example from Belgium
Authors: Baeteman Cecile , Scott David B. , Van Strydonck Mark
Published: November 2002

This paper presents the results of an investigation of late Holocene deposits on the Belgian coastal plain. The upper clastic deposits overlying the uppermost intercalated peat bed were studied on the basis of lithology, radiocarbon dates and foraminiferal assemblages to determine why silting‐up phases or peat beds are lacking, and to establish the evolution of the sedimentary environments as well as the age of the deposits. Two contrasting sites, in quite different locations and showing a different stratigraphy, were studied. It appears that the coastal evolution was not gradual and continuous, but characterised by short periods with high‐energy conditions alternating with long periods where low‐energy conditions and little sedimentation prevailed. The evolution is determined mainly by tidal channel activity. At about 3400 cal. yr BP, the peat was eroded in narrow zones by the main tidal channels and this until the landward limit of the plain. The peat was only partly flooded and mudflats fringed the channels. With time, new tributaries formed and the channel network progressively enlarged. The channels were rapidly filled, followed by a period of little sedimentation, which lasted at least until 1400–1200 cal. yr BP. The following channel activity is characterised by lateral sedimentation, rather than vertical erosion, together with increased sediment reworking. The mechanisms of coastal change in the late Holocene might be similar over the entire plain, but the timing of the changes is certainly not. Copyright © 2002 John Wiley & Sons, Ltd.
Fluctuations in relative sea‐level during the past 3000 yr in the Onnetoh estuary, Hokkaido, northern Japan
Authors: Sawai Yuki , Nasu Hiroo , Yasuda Yoshinori
Published: November 2002

This paper presents the results of a litho‐, bio‐ and chronostratigraphical study of the evidence for late Holocene sea‐level change, palaeoseismicity and coastal evolution at the Onnetoh estuary, northwest Japan. Alternating peat and mud couplets record evidence for four falls in relative sea‐level since ca. 2500 cal. yr BP. In the latest instance, intertidal mud with a salt‐tolerant diatom and plant macrofossil flora is abruptly overlain by a freshwater peat containing abundant macrofossil remains of the conifer Picea glehnii. These stratigraphical changes record an abrupt change from tidal flat to upland, with no intermediate transition through saltmarsh. In the other three instances, the stratigraphy records a more gradual fall in relative sea‐level, as shown by gradational stratigraphical contacts and transitional diatom and plant macrofossil assemblages. Once established, these freshwater peat communities are gradually submerged and become overlain by saltmarsh and then intertidal muds. Radiocarbon ages and tephra date the emergence events to 2700–1750 (gradual), 1350–950 (gradual), 650–300 (gradual) and ca. 400 cal. yr BP (abrupt). These ages are similar to a sequence of emergence events recorded at the Akkeshi estuary, 70 km to the west of the present study site. The three falls in relative sea‐level may record coseismic, or swift post‐seismic, uplift caused by plate boundary subduction earthquakes on the Kurile subduction zone. The oldest relative sea‐level fall is correlated with the so‐called ‘Yayoi regression’, dated to 1500–3000 cal yr BP in other parts of Japan. Copyright © 2002 John Wiley & Sons, Ltd.
Late Quaternary sea‐level change and isostatic and tectonic land movements along the Belgian–Dutch North Sea coast: geological data and model results
Authors: Kiden P. , Denys L. , Johnston P.
Published: November 2002

Early and middle Holocene sea‐level data from Belgium plot ca. 2 m above data from the western Netherlands, reflecting differential tectonic and isostatic movements. The total uplift rate of Belgium relative to the western Netherlands decays gradually from 0.66 m kyr−1 at 7500 cal. yr BP to less than 0.25 m kyr−1 since 5000 cal. yr BP. The tectonic component of this relative movement, inferred from Eemian sea‐level data, is in the order of 0.06 to 0.16 m kyr−1. The isostatic component of the uplift is related to the last phase of the collapse of a peripheral bulge under The Netherlands and the Dutch and German sectors of the North Sea, and to hydroisostatic subsidence of the North Sea basin caused by water loading as sea‐level rose. Comparisons with isostatic rebound models show that they predict well the Holocene isostatic movement between Belgium and the western Netherlands, and that the predictions are improved when the tectonic component is removed from the observations. Preliminary evaluation of sea‐level data from the Dutch sector of the North Sea shows that glacio‐hydroisostatic subsidence relative to Belgium was significantly greater than for the western Netherlands coastal area, and spatially highly variable. Copyright © 2002 John Wiley & Sons, Ltd.
Holocene land‐ and sea‐level changes in Great Britain
Authors: Shennan Ian , Horton Ben
Published: November 2002

Analysis of more than 1200 radiocarbon dated samples that constrain relative sea‐levels in Great Britain over the past 16 000 yr provides estimates of current land‐level changes (negative of relative sea‐level change). Maximum relative land uplift occurs in central and western Scotland, ca. 1.6 mm yr−1, and maximum subsidence is in southwest England, ca. 1.2 mm yr−1. Sediment consolidation, arising from autocompaction as the sediment accumulates and from land drainage, increases the subsidence in areas with thick sequences of Holocene sediments, with an average effect equivalent to at least an extra ca. 0.2 mm yr−1 land subsidence, but more in parts of southeast England, 0.5–1.1 mm yr−1. Modelled changes in tidal range during the mid‐ to late Holocene in eastern England suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified. The effect is most significant for large coastal lowlands, the Fenland and Humber (ca. 0.5 and 0.6 mm yr−1), that were tidal embayments during the mid‐ to late Holocene. Copyright © 2002 John Wiley & Sons, Ltd.
Global glacial isostatic adjustment: palaeogeodetic and space‐geodetic tests of the ICE‐4G (VM2) model
Authors: Peltier W. R.
Published: November 2002

Analyses of the global process of glacial isostatic adjustment and post‐glacial relative sea‐level change continue to deliver important insights into Earth system form and process. One successful model of the related phenomenology is based upon a spherically symmetric internal viscoelastic structure for the solid Earth, which has been denoted VM2, and a model of the most recent deglaciation event of the current ice‐age, denoted ICE‐4G. The primary purpose of this paper is to describe several new a posteriori tests that have recently been performed to further investigate the quality of this global ‘solution’ to the inverse problem for both mantle viscosity and deglaciation history that is posed by the observables associated with this large‐scale geodynamic phenomenon. I focus especially upon the ‘misfits’ of observations to the theoretical predictions of this model, which I am currently using to further refine its properties, and upon predictions made using it of geophysical signals that should soon become visible in the context of the Gravity Recovery and Climate Experiment (GRACE) satellite mission. Among the required refinements to ICE‐4G, one that is necessary to eliminate a recently revealed misfit to space geodetic constraints on the present‐day rate of radial motion at the Yellowknife location well to the west of Hudson Bay, and a similar misfit to absolute gravity measurements to the southwest of the Bay, is the insertion of a ‘Keewatin Dome’ of thick ice centred over Yellowknife with a ridge of ice extending to the south east. In the geomorphological literature, the existence of such a Keewatin Dome previously has been hypothesised but chronological control was lacking on the surface features that suggested its former existence. An important additional constraint that requires the late glacial existence of this important feature consists of new inferences of the Last Glacial Maximum lowstand of the sea from sites in the far field of the main concentrations of land ice. Copyright © 2002 John Wiley & Sons, Ltd.
Pleistocene coastal stratigraphy, sea‐level highstands and neotectonism of the southern Australian passive continental margin—a review
Authors: Murray‐Wallace Colin V.
Published: November 2002

Located in a tectonically stable, intraplate setting and in the far field of former ice sheets, the southern Australian passive continental margin represents a globally important region for quantifying sea level during Pleistocene highstands. The stratigraphical record of the southern Australian margin is dominated by geographically extensive coastal barrier, estuarine and peritidal landforms of bioclastic, temperate carbonate affinity, a function of regional aridity. Siliciclastic successions dominate the eastern Australian coastline. Despite the generally high level of tectonic stability, regional contrasts are evident in the elevation of Pleistocene shoreline deposits that largely relate to pre‐Quaternary geotectonic setting. The most complete record of Pleistocene highstand deposits occurs in the Murray Basin–Coorong Coastal Plain region, and indicates that interglacial sea‐level highstands, for at least the past 11 interglacials, did not deviate by more than 6 m from present sea‐level. The Pleistocene marginal marine record of southern Australia is dominantly represented by coastal successions deposited during marine oxygen isotope stages 5e and 7, equating with relative sea‐level maxima of 2–6 m and greater than 1 m above present sea‐level (APSL) respectively. Intertidal facies of Late Pleistocene interstadial successions rarely occur above present sea level. The most reliable record of glacio‐eustatic (ice equivalent) sea level is registered on coastlines developed on stable Precambrian cratons such as the Gawler Craton (Eyre Peninsula), where a consistent elevation of 2 m APSL is registered for over 500 km for the last interglacial shoreline (125 ka). Copyright © 2002 John Wiley & Sons, Ltd.
Predicted and observed Holocene sea‐levels on the Australian coast: what do they indicate about hydro‐isostatic models in far‐field sites?
Authors: Haworth R. J. , Baker R. G. V. , Flood P. G.
Published: November 2002

Data relating to Holocene sea‐level elevations and ages, obtained by radiocarbon dating of relict calcareous skeletons of intertidal organisms from widely spaced parts of the Australian coast, a far‐field region of comparative tectonic stability, are divisible into two sets, namely: pre‐ and post‐ ca. 3600 yr BP. The older ages are from material consistently between 1.5 m and 2.2 m higher than present sea‐level, whereas the younger ages (ca. 3600–1500 yr BP) generally cluster around 1 m above present sea‐level. The elevations do not display any decline in amplitude from north to south over an extensive transect, contrary to predictions by hydro‐isostatic models. Also, there appears to be little difference between time–elevation results for the coasts of North Queensland, New South Wales and the Bass Strait region adjacent to Tasmania, despite differences in the width of the continental shelf in these three locations, and the expectation of some hydro‐isostatic warping of the continental shelf subsequent to the onset of the Holocene transgression. Results from the south and southwest coasts of Western Australia also display similar elevations to the east coast for the same time periods. There is sufficient evidence extending over 20° of latitude to suggest that north–south differences related to hydro‐isostatic influence is limited or non‐existent. There is insufficient data to test hydro‐isostatic models across continental shelves. Hydro‐isostasy, and the lithological elasticity it reflects, may not be as pronounced in far‐field sites with narrow continental shelves as models predict. Stable far‐field passive continental margins may be the best place to measure the ratio of inputs of eustatic and hydro‐isostatic influences on Holocene relative sea‐levels. Copyright © 2002 John Wiley & Sons, Ltd.
Contemporary and fossil foraminifera from isolation basins in northwest Scotland
Authors: Lloyd J. M. , Evans J. R.
Published: November 2002

Isolation basins are widely used in sea‐level reconstructions, but contemporary analogues have been poorly studied comparatively. Recent research has identified isolation basins with extended transitional isolation contacts that pose problems in sea‐level interpretations. This paper presents foraminiferal results from 24 contemporary isolation basins combined with data from two isolation basins with extended isolation contacts. Foraminiferal associations identified from the contemporary basins show a clear relationship with water salinity and sill altitude that supports interpretation of the extended fossil sequences. An association dominated by Miliammina fusca, Mf, signifies a basin close to final isolation from marine influence. Increasing marine inundation of basins is signified by a series of associations dominated by the following foraminifera; Ja, Jadammina macrescens and M. fusca; ME, M. fusca and Elphidium williamsoni; Ew, E. williamsoni; HE, Haynesina germanica and E. williamsoni; Nd, Nonion depressulus. These associations can be used to interpret the sedimentary isolation sequences from Loch nan Corr and Rumach VI. A pilot study of the stable isotope signature from the two species H. germanica and E. williamsoni is reported from Rumach VI and Loch nan Corr. The results show the potential of stable isotope analysis for environmental reconstruction from isolation basins, in particular using δ18O for salinity reconstruction. Copyright © 2002 John Wiley & Sons, Ltd.
Holocene uplift rates and historical rapid sea‐level changes at the Gargano promontory, Italy
Authors: Mastronuzzi Giuseppe , Sansò Paolo
Published: November 2002

This paper uses a combination of geomorphological and radiometric data from the northern coast of the Gargano promontory (comprising the Fortore River coastal plain and Punta delle Pietre Nere) to reconstruct Holocene uplift rates. The coastal plain consists of a sandy progradational beach sequence that extends seawards from the base of a relict cliff. This cliff probably marks the maximum position reached by the Holocene transgression. Altimetric data compared with the age of beach deposits and the available eustatic sea‐level curves indicate an average Holocene uplift rate of 1.5 mm yr−1. A similar uplift rate has been estimated by dating a bioherm constituted of calcareous algae, Vermetids and subordinately by Cladocora caespitosa (L.), which crops out in the locality of Punta delle Pietre Nere. This deposit, which was previously assigned an interglacial age, yielded a mid‐Holocene age by means of Th/U and 14C age determinations.

Our observations also reveal evidence for coseismic deformation along the northern coast of the Gargano promontory during the last millennium. Vertical displacements of >0.5 m have affected the Punta delle Pietre Nere coastal block, and were preceded by periods of slow coastal subsidence, which increased rapidly shortly before a major earthquake. Copyright © 2002 John Wiley & Sons, Ltd.
Late Quaternary relative sea‐level changes and vertical movements at Lipari (Aeolian Islands)
Authors: Calanchi N. , Lucchi F. , Pirazzoli P. A. , Romagnoli C. , Tranne C. A. , Radtke U. , Reyss J. L. , Rossi P. L.
Published: November 2002

Indicators of former sea‐levels are recognised on the emergent portion of Lipari, Aeolian Islands. They correlate with three raised shorelines, located at elevations of 43–45 m above present sea‐level (I), 23–27 m (II) and about 12 m (III). According to stratigraphical constraints, these shorelines correlate with the sea‐level highstands corresponding to marine oxygen isotope substages 5e (124 ka), 5c (100 ka) and 5a (81 ka), respectively. The correlation of the shoreline I with substage 5e is supported by a U/Th age (119 ± 6 ka) obtained from corals. Chronological and height data relevant to the fossil shorelines indicate that Lipari was affected by uplift with an average rate of 0.34 mm yr−1 during the past 125 ka. This uplift rate accords with the average uplift rates obtained, during the same time period, from the nearby islands of Filicudi (0.31 mm yr−1) and Salina (0.36 mm yr−1). Combined, these data suggest a similar uplift trend related to regional tectonic processes.

In contrast to the long‐term uplift, a localised submergence trend, documented especially for the last century, affects the eastern coast of Lipari. This subsidence is related to neo‐ and/or volcano‐tectonic processes. Copyright © 2002 John Wiley & Sons, Ltd.
Perception of intrinsic and extrinsic respiratory loads in children with life‐threatening asthma
Authors: Julius Steven M. , Davenport Kathleen L. , Davenport Paul W.
Published: November 2002

There is a subpopulation of asthmatic patients with a history of life‐threatening asthma (LTA) who have a reduced perception of respiratory loads. The aim of this study was to determine if these patients have a reduced perception of both intrinsic and extrinsic loads. Children with asthma were classified into life‐threatening asthma and control asthmatic groups. Perception of extrinsic loads was assessed by magnitude estimation of inspiratory resistive loads. Magnitude estimation was measured with handgrip estimation of resistive load magnitude. Perception of intrinsic loads was by methacholine bronchoprovocation in doses sufficient to a drop to 40% below baseline of forced expired volume in 1 sec (FEV1). Chest tightness, breathlessness, and air hunger, as estimated by a Borg scale were, used to rate methacholine perception. Life‐threatening asthma subjects had a lower slope than nonlife‐threatening asthma subjects for magnitude estimation of resistive loads. Life‐threatening asthma patients also had a lower maximum Borg score for all three symptoms. There was no significant difference in magnitude estimation of symptom type.

These results suggest that life‐threatening asthma subjects have poor perception of extrinsic and intrinsic loads. This suggests that there is a similarity between the sensations elicited by intrinsic and extrinsic loads, allowing for the identification of poor‐perceiving patients with either method of assessment and who suffer from life‐threatening asthma. Pediatr Pulmonol. 2002; 34:425–433. © 2002 Wiley‐Liss, Inc.
Explicitly correlated SCF study of anharmonic vibrations in (H2O)2
Authors: Shillady Donald D. , Craig John , Rutan Sarah , Rao Bijan
Published: November 2002

Modeling solvation in high‐pressure liquid chromatography (HPLC) requires calculation of anharmonic vibrational frequencies of solvent clusters for a statistical partition function. An efficient computational method that includes electron correlation is highly desirable for large clusters. A modified version of the “soft Coulomb hole” method of Chakravorty and Clementi has recently been implemented in a Gaussian‐lobe‐orbital (GLO) program (PCLOBE) to include explicit electron–electron correlation in molecules. The soft Coulomb hole is based on a modified form of Coulomb's law:

An algorithm has been developed to obtain the parameter “w” from a polynomial in the effective scaling of each primitive Gaussian orbital relative to the best single Gaussian of the H1s orbital. This method yields over 90% of the correlation energy for molecules of low symmetry for which the original formula of Chakravorty and Clementi does not apply. In this work, all the vibrations of the water dimer are treated anharmonically. A quartic perturbation of the harmonic vibrational modes is constrained to be equal to the exact Morse potential eigenvalue based on a three‐point fit. This work evaluates the usefulness of fitting a Morse potential to a hydrogen bond vibrational mode and finds it to be slightly better than using MP2 vibrational analysis for this important dimer. A three‐point estimate of the depth, De, of a Morse potential leads to a correction formula for anharmonicity in terms of the perturbed harmonic frequency:

When scaled by 0.9141, the harmonic Morse method leads to essentially the same results as scaling the BPW91 local density method by 0.9827. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Fully relativistic density functional calculations on hydroxylated actinide oxide surfaces
Authors: Boettger J. C. , Ray A. K.
Published: November 2002

The linear combinations of Gaussian‐type orbitals–fitting function (LCGTO‐FF) method has been used to investigate the cohesive properties of three fluorite structure actinide oxides (ThO2, UO2, and PuO2), and their clean and hydroxylated (111) surfaces, within the generalized gradient approximation (GGA) to density functional theory (DFT). Relativistic effects have been considered at both the scalar‐relativistic and the fully relativistic (spin–orbit coupling included) levels of approximation. It is found here that the 5f states have only a minimal effect on the cohesive properties of these systems, despite the fact that the two heavier actinide oxides (both Mott–Hubbard‐type insulators) are incorrectly predicted to be good metals. The cause of this insensitivity to the spurious metallic nature of the 5f states is elucidated. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Rosetta Stone of the genetic language
Authors: Lucas Amand A.
Published: November 2002

The paper begins with a guided tour through the history of several major deciphering events in modern science, going from the determination of the wave nature of visible light in the early 19th century, via the discovery of X‐rays and their electromagnetic nature around the turn of the 19th century, and onward to the great decipherments of molecular biology of recent times. The central piece of the latter decoding efforts, i.e., the measurement of the X‐ray diffraction diagram of DNA, occurred in the middle of the 20th century and lead Watson and Crick to the discovery of the structure of the molecule. In the second part of the paper, a detailed analysis is given of the relationship between the gross features of the X‐ray diagram and the corresponding structural elements of the doubly helical DNA backbone. In the third part, simple optical diffraction experiments, using a laser pointer and a single diffraction slide, are described which allow to mimic the X‐ray diffraction experiment and reproduce all the major characteristics of the observed X‐ray picture. Finally, the paper presents a quantitative description of the wave diffraction by an atomic helix and discusses the mathematical origin of the various features of the X‐ray and optical patterns. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
HF–CC model for atoms and molecules
Authors: Clementi E. , Corongiu G.
Published: November 2002

The Hartree–Fock–Clementi–Corongiu method (HF–CC) is revisited, aiming at an unified formulation for post‐HF energy computations in atomic and molecular systems. For atomic systems new parameterizations of the HF–CC functional are proposed for the computation of atoms. The previous HF–CC molecular functional (Clementi, E.; Corongiu, G. Theochem 2001, 543, 39), revisited and recalibrated with a new optimization of the parameters, is tested with a sample of 131 molecules, including radicals, H‐bond, and van der Waals systems. The atomization energy is decomposed into “HF classic” energy (the sum of the HF nuclear electron, HF kinetic, and HF Coulomb energies), “HF exchange” energy, and correlation energy; the latter is computed with a scaling functional with atomic, covalent, ionic, and van der Waals contributions. For the sample of 131 molecules, the computed HF–CC atomization energies have an average standard deviation of 1.89 kcal/mol. The atomic and molecular components of the correlation energy are decomposed into nuclear electron, kinetic, Coulomb, and exchange contributions; these decompositions characterize the HF–CC model and are used to explain the origin of the chemical bond. Computations on van der Waals systems show the validity of the HF–CC method also for long‐range weak interactions. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Hydrogen‐bonding effects on electronic g‐tensors of semiquinone anion radicals: Relativistic density functional investigation
Authors: Neyman Konstantin M. , Ganyushin Dmitri I. , Rinkevičius Žilvinas , Rösch Notker
Published: November 2002

We report results of systematic g‐tensor calculations of hydrogen‐bonded complexes of two benchmark semiquinone anion radicals, 1,4‐benzoquinone and tetramethyl‐1,4‐benzoquinone (duroquinone), with water and methanol molecules. The calculations have been carried out with the help of a recently developed g‐tensor module that is based on a relativistic density functional method that takes spin–orbit interaction self‐consistently into account. We demonstrate the applicability of this new computational scheme to describe quantitatively delicate effects of hydrogen bonding on electronic g‐tensor values. Also, we explored general trends of how g‐tensors depend on the structure and stoichiometry of hydrogen‐bonded semiquinone complexes. Complexes exhibiting one hydrogen bond per oxygen atom of the quinones with a linear arrangement of the CO … H moieties were shown to feature g‐shifts induced by these hydrogen bonds that are in close agreement with measured electron paramagnetic resonance data. Based on deviations of calculated and measured g‐components, we classify all other model complexes studied as less probable under the experimental conditions. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Electronic excitations and first hyperpolarizability of 2‐methyl‐4‐nitroaniline clusters
Authors: Guillaume Maxime , Botek Edith , Champagne Benoît , Castet Frédéric , Ducasse Laurent
Published: November 2002

The crystal packing effects upon the static and dynamic first hyperpolarizability of 2‐methyl‐4‐nitroaniline (MNA) clusters have been addressed at the TDHF/AM1 level. Due to electrostatic interactions, in 1‐D arrays of MNA unit cells extending along the a crystallographic axis, the effective hyperpolarizability strongly increases whereas stacking unit cells along the b or c axes leads to a reduction of these quantities. These effects are magnified in the case of frequency‐dependent quantities. The first hyperpolarizability variations can mostly be related to bathochromatic and hypsochromatic shifts as well as to changes in transition dipole moments of the low‐energy excited states that dominate the UV/visible absorption spectra. From calculations performed at the CIS/INDO/S level of approximation, these dominant excited states present an important intramolecular charge transfer character and bathochromatic (hypsochromatic) shifts are associated with increase (decrease) of the transition dipole moments. In addition, a large number of intermolecular charge‐transfer excited states have been detected. In the small MNA aggregates as well as in clusters extending only along the b or c crystallographic axes, these excited states possess small transition dipole moments. On the other hand, when stacking MNA unit cells along the a axis the electrostatic interactions induce a decrease of the excitation energies and an increase of the transition dipole moments of these intermolecular charge transfer states. As a consequence, they account for a nonnegligible contribution to the first hyperpolarizability. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Designer polynomials, discrete variable representations, and the Schrödinger equation
Authors: Weatherford Charles A. , Red Eddie , Wynn Albert
Published: November 2002

The general procedure for constructing a set of orthonormal polynomials is given for an arbitrary positive definite weight function, w(x), in the interval [a, b]. The Lanczos method is used to generate the three‐term recursion relation, which is then used to produce the polynomial coefficients. A discrete variable representation (DVR) is constructed from Gaussian nodes and weights that result from the three‐term recursion relation. These are termed “designer polynomials” and the associated “designer DVRs.” It will be shown by construction that every such set of “synthetic polynomials” carries an associated DVR. The term “designer” derives from the fact that the interval [a, b] and the weight function w(x) are arbitrary (except that w(x) must be positive definite on [a, b] and must have continuous derivatives except at a finite number of isolated discontinuities) and may be adapted to the physical problem of interest. The difficulties of applying a DVR to a “bare” Coulomb problem will be illustrated on a “toy” model in one dimension (1‐D hydrogen atom). A solution for the 1‐D Coulomb problem will be given, thereby motivating the need for designer DVRs. In doing so, a new set of polynomials is defined with a weight function w(x) = |x|kexp(−α|x|), (such that k = −1, 0, +1, +2, …) between the symmetrical limits [−∞, +∞]. These are called “synthetic Cartesian exponential polynomials (SCEP).” These polynomials are then used in a spectral and pseudospectral (DVR) representation to solve the 1‐D hydrogen atom problem. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Influence of many‐body interactions on resistance of a grain boundary with respect to a sliding shift
Authors: Dorfman Simon , Fuks David , Malbouisson Luiz A. C. , Mundim Kleber C. , Ellis Donald E.
Published: November 2002

We performed nonempirical simulations of the properties of the tungsten Σ3(111) grain boundary (GB) with a boron atom and demonstrate the influence of many‐body interactions on the resistance of the GB with respect to sliding. We also studied the propagation of relaxations in the vicinity of the GB. The many‐body interatomic potentials (IP) used in these simulations were obtained with the recursion procedure from ab initio total energy calculations. At each step of the slip process, the equilibrium positions of the atoms near GB were calculated with the generalized simulated annealing technique. It was demonstrated how the sliding shift influences the penetration of the elastic field inside the grain. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Structure and relative energies of the conformers of n‐butyl cyanide and 5‐hexynenitrile
Authors: Atticks Karissa A. , Bohn Robert K. , Michels H. Harvey
Published: November 2002

The microwave spectrum of n‐butyl cyanide and 5‐hexynenitrile (5‐cyano‐1‐pentyne) reveal the presence of three conformers that have been characterized. Each of these molecules can exist in anti–anti (AA), anti–gauche (AG), gauche–anti (GA), gauche–gauche (GG trans), and gauche–gauche′ (GG′ cis) conformations. The first three conformers have been observed experimentally and characterized in both compounds. In previous studies, we examined the microwave spectrum of the related n‐butyl acetylene molecule and observed and characterized the mono‐13C‐isotopomers of the AA and GA forms of n‐butyl acetylene as well as the AG form, albeit at lower intensity. The GG conformers, in both cis and trans arrangements have not been identified to date for these molecules. The structures and energies of the five possible conformers of each molecule have been determined through quantum mechanical calculations at the HF and MP2 levels of theory, using both double‐zeta [6‐31G(d,p)] and triple‐zeta [6‐311+G(d,p)] basis sets. The calculated energies of the five possible conformers of each molecule are close, and a change in the relative stability order of these conformers is found at different levels of theory. For n‐butyl cyanide and n‐butyl acetylene, the GA form lies lowest in energy, both experimentally and at the MP2 level of theory. For 5‐hexynenitrile, the GG trans form is predicted to lie lowest in energy. The predicted conformer stability order is in agreement with a model of a net attractive electrostatic interaction between the π‐electron densities and the closest hydrogen on the next‐nearest‐neighbor carbon. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Substituent effects on the electronic structure and pKa of benzoic acid
Authors: Hollingsworth Chad A. , Seybold Paul G. , Hadad Christopher M.
Published: November 2002

The effects of substituents on the pKas of a set of 16 substituted benzoic acids have been examined using density functional theory [B3LYP/6‐311G(d, p)] calculations. A variety of quantum chemical parameters were examined as indicators for the variations observed in the experimental pKas, including the Löwdin, Mulliken, AIM, and natural population analysis charges (QL, QM, QA, and Qn) on atoms of the dissociating carboxylic acid group, the energy difference (ΔEprot) between the carboxylic acid and its conjugate base, and the Wiberg bond index. Several of these calculated quantities yielded excellent correlations with the experimental pKa: ΔHprot, r2 = 0.958; QL(H), r2 = 0.963; Qn(CO2H), r2 = 0.969; QL(CO), r2 = 0.970; and QL(CO2H), r2 = 0.978. The best correlation observed with the pKa, as expected, was from the empirical Hammett constants designed for this purpose (r2 = 0.999). © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Quadricyclane radical cation isomerization reactions: A theoretical study
Authors: Larsson Per‐Erik , Salhi‐Benachenhou Nessima , Dong Xicheng , Lunell Sten
Published: November 2002

On the C7H8·+ potential energy surface studied in this work, the electrocyclic isomerization of the quadricyclane (Q·+) to the norbornadiene (N·+) radical cations has attracted much attention. Our interest, however, concerns alternative rearrangement reactions on this surface. Using quantum chemical methods, B3LYP/6‐311+G(d,p), MP2/6‐31G(d,p), and single‐point CCSD(T)/6‐311+G(d,p), a skeletal rearrangement path leading from Q·+ to the bicyclo[3,2,0]hepta‐2,6‐diene radical cation (BHD·+) is found. The barrier for this path is 4.9 kcal/mol higher at the CCSD(T)/6‐311+G(d,p)//B3LYP/6‐311+G(d,p) level than the Q·+ to N·+ barrier. Moreover, this rearrangement is found to proceed through an intermediate, bicyclo[2.2.1]hepta‐2‐ene cation (BHE·+), with a conversion barrier to BHD·+ of 8.1 kcal/mol while the barrier for conversion back to Q·+ is 12.8 kcal/mol, computed with CCSD(T)/6‐311+G(d,p)//B3LYP/6‐311+G(d,p). Interestingly, the 1H hyperfine coupling constants computed for this intermediate structure show an excellent agreement with the experiment by Williams and coworkers. This ESR spectrum, observed after irradiation of N and Q loaded CF3CCl3 matrices, was assigned to BHD·+; our calculations, however, show that it is BHE·+ that gives rise to the observed spectrum. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Treatment of shape and Auger resonances using the dilated electron propagator
Authors: Mishra Manoj K. , Venkatnathan Arun
Published: November 2002

An overview of the dilated electron propagator method based on operators defined on biorthogonal orbitals from bivariationally obtained complex scaled SCF procedure is presented and discussed. Results from applications to atomic and molecular electron attachment and detachment resonances using different decouplings of the dilated electron propagator are analyzed to adduce the role of correlation and relaxation effects in the formation and decay of shape and Auger resonances. Feynman–Dyson amplitudes of the dilated electron propagator are examined to try and unravel the mechanistic underpinnings of these resonances. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002