bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations into the polymorphisms at the ECM38 locus of two widely used Saccharomyces cerevisiae S288C strains, YPH499 and BY4742
Authors: Kumar Chitranshu , Sharma Rakesh , Bachhawat Anand Kumar
Published: July 2003

The ECM38 gene encodes the γ‐glutamyl transpeptidase enzyme, an enzyme involved in glutathione turnover. The enzyme was found to be present in the S288C strain, BY4742, but absent in another widely used strain congenic to S288C, YPH499. Cloning and sequencing the genes from these yeasts indicated the presence of 11 single nucleotide polymorphisms in the coding region and eight single nucleotide polymorphisms in the promoter region of the ECM38 gene of YPH499 (but none in that of BY4742). One of the SNPs in the ECM38 ORF led to a G → D conversion in a region conserved in all γ‐GT enzymes and was found to be responsible for the loss of activity in this strain. The presence of γ‐GT activity in other YPH strains led us to trace the origins of the polymorphisms in YPH499. Our results indicated that among the progenitor strains, YPH1 and YPH2, YPH1 carried the polymorphisms seen in YPH499 and also lacked the γ‐GT activity. The implications of these results for the use of these widely used S288C strains and the origin of these single nucleotide polymorphisms are presented. Copyright © 2003 John Wiley & Sons, Ltd.
The pfr1 gene from the human pathogenic fungus Paracoccidioides brasiliensis encodes a half‐ABC transporter that is transcribed in response to treatment with fluconazole
Authors: Gray Christopher H. , Ines Borges‐Walmsley M. , Evans Gareth J. , Walmsley Adrian R.
Published: July 2003

We have isolated a gene that encodes a half‐ABC‐transporter, designated Pfr1, from the dimorphic human pathogenic fungus Paracoccidioides brasiliensis, which has high identity with members of the ABC‐superfamily involved in multidrug resistance. The pfr1 gene is predicted to encode a 827 amino acid protein that, in common with mammalian Mdr1, has a TM‐NBD topology. The transcription of the pfr1 gene is induced by the triazole drug fluconazole but not by amphotericin B, suggesting a role in transport‐mediated azole resistance. However, Pfr1 has greatest identity to the mitochondrial ABC transporters Mdl1 and Mdl2 from Saccharomyces cerevisiae and mammalian ABC‐me, with identities of 47.2%, 40.6% and 39.5%, respectively, over the length of these proteins. Furthermore, the N‐terminus of Pfr1 is rich in positively charged residues, a feature of mitochondrial targeting sequences. Considering these features, it seems likely that Pfr1 is a mitochondrial protein. Previous studies have revealed that the acquisition of azole resistance in S. cerevisiae is linked to mitochondrial loss and, conversely, that mitochondrial dysfunction can lead to the upregulation of PDR transporters mediated by the transcription factor Pdr3. Our studies suggest that a mitochondrial ABC transporter is induced as part of the cellular response to drug treatment. The promoter region of pfr1 contains a PDRE‐like consensus sequence to which Pdr3 binds, which may be the element responsible for the upregulation of Pfr1 in response to fluconazole. The nucleotide binding domain of Pfr1 was expressed and purified from Escherichia coli and shown to retain ATPase activity, consistent with Pfr1 functioning as a homodimeric transport ATPase. Copyright © 2003 John Wiley & Sons, Ltd.
A diverse set of nuclear RNAs transfer between nuclei of yeast heterokaryons
Authors: Olson Brian L. , Siliciano Paul G.
Published: July 2003

Small nuclear RNAs and small nucleolar RNAs function in the nucleus of eukaryotic cells during pre‐mRNA splicing and ribosomal RNA processing, respectively. In metazoan cells, the small nuclear RNAs shuttle between the nucleus and the cytoplasm during ribonucleoprotein particle assembly. Nuclear export of these small RNAs in yeast, however, has not been demonstrated. Therefore, we have attempted to visualize internuclear RNA movements by in situ hybridization in heterokaryon yeast cells. Using the kar1Δ15 mutation to block karyogamy, we mated two strains, each expressing a unique allele of U1 snRNA. In these heterokaryons, we observed a time‐dependent transfer of U1 snRNA from one nucleus to the other. This transfer was reduced two‐fold by the addition of the Crm1p‐inhibitor leptomycin B. Interestingly, however, we observed identical transfer of the U2 and U6 snRNAs and SNR4, SNR8, SNR9 and SNR11 snoRNAs. Remarkably, when the U2, U6 or SNR4 RNAs were observed in the same heterokaryon as the U1 snRNA, both RNAs always transferred simultaneously. These data suggest a global leaking or transport of material between nuclei of yeast heterokaryons. Our results suggest that caution must be taken when testing nuclear envelope shuttling in yeast heterokaryons. Copyright © 2003 John Wiley & Sons, Ltd.
Cloning and chromosomal mapping of URA3 genes of Pichia farinosa and P. sorbitophila encoding orotidine‐5′‐phosphate decarboxylase
Authors: Suzuki Chise , Yoshida Nao , Okano Etsuko , Kawasumi Toshiyuki , Kashiwagi Yutaka
Published: July 2003

The PfURA3 gene, which encodes orotidine‐5′‐phosphate decarboxylase, of osmotolerant yeast Pichia farinosa NFRI 3621, was cloned by complementation of the ura3 mutation of Saccharomyces cerevisiae. The nucleotide sequence of the PfURA3 gene and its deduced amino acid sequence indicated that the gene encodes a protein (PfUra3p) of 267 amino acids. Pulsed‐field gel electrophoresis and subsequent Southern blot analysis showed that the genome of P. farinosa NFRI 3621 consisted of seven chromosomes, each approximately 1.1–2.2 Mb in size (11.8 Mb in total) and that PfURA3 was located on chromosome V. Pichia sorbitophila is considered as a synonym of P. farinosa. The genome of P. sorbitophila IFO10021 may consist of 12 chromosomes, each approximately 1.2–2.2 Mb in size. P. sorbitophila has two copies of URA3 genes, termed PsURA3 and PsURA30, which were located on chromosome VIII and III, respectively. The difference between PfURA3 and PsURA3 was only two amino acid substitutions, whereas that between PsURA3 and PsURA30 was six amino acid substitutions and the deletion of the C‐terminal amino acid by a stop codon insertion. The sequences of PfURA3, PsURA3 and PsURA30 have been deposited in the DDBJ data library under Accession Nos AB071417, AB109042 and AB109043, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
A genetic screen for yeast genes induced by sustained osmotic stress
Authors: Runner Vanessa M. , Brewster Jay L.
Published: July 2003

The budding yeast, Saccharomyces cerevisiae, responds to changes in external osmolarity through the activation of an osmosensing signal transduction pathway. Using lacZ–reporter gene fusions, clonal cell lines were screened for levels of β‐galactosidase activity in the presence or absence of osmotic stress. A screen of 9000 transformants displayed 663 (7%) gene fusions that were active in rich medium. Each of the transformants were also assayed for gene activity 24 h following a transfer to high osmolarity medium (0.6 M NaCl) and of the 9000 clonal cell lines, 86 (1%) displayed a decrease in expression, and seven (0.1%) displayed a reproducible increase in gene expression during primary screening. The chromosomal loci of the lacZ insertions were determined, and the gene(s) associated with that site was examined for osmotically induced expression using RNA blot analysis. Five stress‐activated genes were analysed by RNA blot: YDL222C, NMD2, PTC7, FAA4 and YRF1. The genes identified by this screen encompass cellular adaptations to stress including signal transduction, protein myristoylation and fatty acid/sphingolipid content in the cell membrane. Copyright © 2003 John Wiley & Sons, Ltd.
Parallel analysis of tagged deletion mutants efficiently identifies genes involved in endoplasmic reticulum biogenesis
Authors: Wright Robin , Parrish Mark L. , Cadera Emily , Larson Lynnelle , Matson Clinton K. , Garrett‐Engele Philip , Armour Chris , Lum Pek Yee , Shoemaker Daniel D.
Published: July 2003

Increased levels of HMG‐CoA reductase induce cell type‐ and isozyme‐specific proliferation of the endoplasmic reticulum. In yeast, the ER proliferations induced by Hmg1p consist of nuclear‐associated stacks of smooth ER membranes known as karmellae. To identify genes required for karmellae assembly, we compared the composition of populations of homozygous diploid S. cerevisiae deletion mutants following 20 generations of growth with and without karmellae. Using an initial population of 1557 deletion mutants, 120 potential mutants were identified as a result of three independent experiments. Each experiment produced a largely non‐overlapping set of potential mutants, suggesting that differences in specific growth conditions could be used to maximize the comprehensiveness of similar parallel analysis screens. Only two genes, UBC7 and YAL011W, were identified in all three experiments. Subsequent analysis of individual mutant strains confirmed that each experiment was identifying valid mutations, based on the mutant's sensitivity to elevated HMG‐CoA reductase and inability to assemble normal karmellae. The largest class of HMG‐CoA reductase‐sensitive mutations was a subset of genes that are involved in chromatin structure and transcriptional regulation, suggesting that karmellae assembly requires changes in transcription or that the presence of karmellae may interfere with normal transcriptional regulation. Copyright © 2003 John Wiley & Sons, Ltd.
“Zu Risiken und Nebenwirkungen fragen Sie Ihren Arzt oder Apotheker“:
Authors: Fischer Katrin , Jungermann Helmut
Published: July 2003

Zusammenfassung. Patienten sollen über Risiken von Behandlungsverfahren und Medikamenten, über Unsicherheiten von Diagnosen und Tests, über Auftretenswahrscheinlichkeiten von Erkrankungen usw. korrekt und angemessen aufgeklärt werden. Sie sollen so darüber aufgeklärt werden, dass sie die Information verstehen und ihre Entscheidung für oder gegen eine Behandlung oder ein Medikament überlegt treffen können. Aber welche Informationen sollen dem Patienten gegeben werden? Wie kann der Patient über Unsicherheiten informiert werden? Welche Faktoren beeinflussen das Verständnis von Unsicherheit? Im ersten Teil dieses Beitrages skizzieren wir einige Probleme vor dem Hintergrund der Forschung zur Risikokommunikation. Im zweiten Teil stellen wir zwei experimentelle Studien vor, in denen untersucht wurde, von welchen Faktoren die Interpretation verbaler Häufigkeitsausdrücke auf Beipackzetteln zu Medikamenten beeinflusst wird. In Studie 1 prüften wir, ob studentische Probanden verbale Angaben wie “selten“ oder “häufig“ nummerisch anders interpretieren, wenn diese auf (stilisierten) Beipackzetteln standen, als wenn sie in einem neutralen Kontext dargeboten wurden. Tatsächlich waren die nummerischen Interpretationen für die verbalen Ausdrücke im medizinischen Kontext deutlich geringer als in der kontextfreien Bedingung. Sie waren zudem von der Schwere der beschriebenen Nebenwirkungen abhängig, aber diese Abhängigkeit verschwand, wenn die Basisrate der Nebenwirkung angegeben wurde. In Studie 2 untersuchten wir den Zusammenhang zwischen der Interpretation der verbalen Ausdrücke, der Beurteilung des Risikos und der Entscheidung über die Einnahme des Medikamentes. Während sich die Risikourteile bei verbal und nummerisch beschriebenen Medikamenten nicht unterschieden, gab es bei den Entscheidungen einen deutlichen Unterschied: Die Pbn waren eher zur Einnahme eines Medikamentes bereit, wenn die Häufigkeiten der Nebenwirkungen nummerisch angegeben wurden, als wenn sie mit den äquivalenten verbalen Ausdrücken angegeben wurden. Zum Abschluss werden einige praktische Implikationen der Befunde für die Kommunikation von Risiken diskutiert.
Risikowahrnehmung von Brustkrebs
Authors: Barth Jürgen , Reitz Frauke , Bengel Jürgen
Published: July 2003

Zusammenfassung. In der Beratung zur prädiktiven genetischen Brustkrebsdiagnostik wird Frauen ihr medizinisches Brustkrebsrisiko erläutert und über das wahrgenommene Brustkrebsrisiko gesprochen. Da Fehleinschätzungen mit unangemessenen gesundheitsbezogenen Überzeugungen und einem inadäquaten Gesundheitsverhalten einhergehen können, werden beide Werte gegenübergestellt. In Beratungskontexten zeigte sich bei der Erfassung des wahrgenommenen Risikos eine überzufällige Häufung von 50-Prozent-Antworten. Die vorliegende Studie prüft, ob mit diesen 50-Prozent-Antworten bestimmte gesundheitsbezogene Kognitionen und Emotionen assoziiert sind. Dazu wurden Frauen der Allgemeinbevölkerung, die ihr persönliches Brustkrebsrisiko auf 50% schätzen, mit Frauen verglichen, die ihr Brustkrebsrisiko realistisch (< 15%) oder pessimistisch (16-49%) schätzen. Der Vergleich der Gruppen erfolgte hinsichtlich soziodemographischer, affektiver und kognitiver Variablen sowie in Bezug auf persönlichkeits- und gesundheitsbezogene Merkmale. Unterschiede zwischen 50-Prozent-Antworterinnen und Realistinnen zeigen, dass 50-Prozent-Antworten als Anzeichen einer erhöhten Angst vor einer Krebserkrankung, einer geringeren Kontroll- bzw. Kompetenzerwartung und einer größeren Unsicherheit bei der Einschätzung des eigenen Brustkrebsrisikos betrachtet werden können. Da sowohl hinsichtlich soziodemographischer Variablen als auch in Bezug auf das Wissen zu brustkrebsspezifischen Risikofaktoren keine Unterschiede zwischen den Gruppen gefunden wurden, ist anzunehmen, dass 50-Prozent-Antworten nicht auf geringeren kognitiven Fähigkeiten beruhen. Im Kontext von medizinischer und genetischer Beratung sollte beachtet werden, dass 50-Prozent-Antworten nicht nur eine Überschätzung des Risikos darstellen, sondern auch Ausdruck von Unsicherheit und Ängstlichkeit sein können.
Adults' Knowledge of General Psychology
Authors: Furnham Adrian , Callahan Inés , Rawles Richard
Published: July 2003

This paper reports on two studies in which different adult populations who had not formally studied psychology completed multiple-choice tests derived from general psychology textbooks to evaluate specific knowledge of the discipline. The aim was to determine to what extent psychology was “common sense” and which personal characteristics, such as sex, education, and age, best predicted correct answers. In the first study, 114 students about to start a psychology degree, and 222 nonstudent adults, completed a 106-item questionnaire taken from a standard textbook. There was considerable variability in the extent to which participants checked the correct answer, with an overall average of only 56% (just above chance). There was no statistical difference between the two groups in knowledge overall or in any particular areas. A regression showed books read and belief in the scientific nature of psychology to be the best predictors of overall knowledge. In the second study, 94 first-year students at the beginning of their course and 136 student applicants completed a 114-item questionnaire derived from a different textbook, this time focusing on child development. There was no difference in the correct responses between a psychology-student and nonstudent group, with both groups getting around 53% of the answers correct. Interest in, and experience of, psychology did not predict total correct scores. Like previous studies in the area, the results failed to indicate any major variables that predict knowledge of psychological processes.
Psychologists Can Do Much to Support Sustainable Development 1Authors' names in alphabetical order. E-mail schmuck@gp.tu-berlin.de and C.A.J.Vlek@ppsw.rug.nl.
Authors: Schmuck Peter , Vlek Charles
Published: July 2003

With our biosphere steadily degrading, a solid psychological perspective on environmental, social, and economic (un)sustainability is urgently needed. This should supplement and strengthen biological, technological, and economic perspectives. After discussing positivistic and constructive psychology, we summarize major environmental problems with their social and economic implications. We also compose some essential psychological reasoning about them, including the commons dilemma model, different behavioral processes and strategies of behavior change, and various aspects of human quality of life (QoL). Psychologists can help analyze and mitigate the biggest sustainability problems: population growth, resource-intensive consumption, and harmful technologies—if their research is well-tuned to other environmental sciences, if the incentive structure for this work is improved, and if more attention is paid to the collective side of human behavior.
Geropsychology and Psychology in the Last Quarter of the 20th Century
Authors: Krampen Günter , Wahl Hans-Werner
Published: July 2003

This paper presents bibliometrical results on the development of gerontopsychology in the last quarter of the 20th century. Analyses are based on the psychology literature documented in PsycINFO, covering mainly publications from the Anglo-American region, and PSYNDEX, covering publications from the German-speaking countries, for the years 1977 to 2000. Results show that both literature bodies on gerontopsychology have steadily grown, in absolute terms, since the beginning of the last quarter of the 20th century. The geropsychology literature in the German-speaking countries has grown faster than the Anglo-American literature. In terms of a relative frequency view, the findings support the notion that geropsychology has found a clear and stable position within psychology as a whole in both research communities, contributing 1-3% to the overall psychology literature and 8-15% (PsycINFO) respectively 30-50% (PSYNDEX) to the overall developmental psychology literature since 1978.
Searching for Information About Financial Decisions in Euro Versus DM
Authors: Jonas Eva , Frey Dieter
Published: July 2003

The introduction of the Euro in Germany took place even though it was considered far less attractive than the former national currency, the German Mark (DM). In this study, we investigated whether the introduction of the Euro has affected how people made a financial investment decision. We found that thinking about investment alternatives using the Euro led to a more negative attitude toward this currency compared to people who were making a financial decision using the DM. In addition, we showed that people searched for more information regarding advantages of the investment alternatives than disadvantages when making an investment decision with the Euro compared to the DM. The findings are discussed with regard to how people deal with the psychological conflict resulting from the preference for the DM alongside the acceptance of the Euro.
An impact of estimating tropospheric delay gradients on precise positioning in the summer using the Japanese nationwide GPS array
Authors: Miyazaki Shin'ichi , Iwabuchi Tetsuya , Heki Kosuke , Naito Isao
Published: July 2003

We investigate the effect of modeling tropospheric delay gradients on the station position estimates using the Japanese nationwide GPS array. The time series shows spatially coherent temporal fluctuations due to the variability of water vapor distribution. This makes it difficult to identify small crustal deformation signals in GPS time series. Precision and accuracy of station positions are known to be improved by modeling the tropospheric delay gradient, and past studies suggest that delay gradient estimates agree well with the collocated water vapor radiometer measurements. Here we pick up two intervals as long as 2 weeks in 1996 summer, when remarkable tropospheric delay gradients are expected, and investigate various influences of tropospheric delay gradients on station position estimates. First, we study spatial patterns of station position deviations caused by azimuthal asymmetry of water vapor distributions from two solutions, i.e., with and without the tropospheric delay gradient model. Second, we compare them with the estimated delay gradients. Site coordinate deviations in the solution without the delay gradient model are negatively correlated with the estimated delay gradients, but such systematic deviations disappear by introducing the delay gradient model. We found that the improvement in position accuracy is significant not only horizontally but also vertically over both of the two time intervals.
Response of the near‐surface carbonate system of the northwestern Arabian Sea to the southwest monsoon and related biological forcing
Authors: Lendt Ralf , Thomas Helmuth , Hupe Axel , Ittekkot Venugopalan
Published: July 2003

Underway measurements of the CO2 partial pressure (pCO2) and the sea surface temperature were made in the northwestern Arabian Sea during late intermonsoon and southwest (SW) monsoon 1997. Additionally, dissolved inorganic carbon (DIC) and total alkalinity were analyzed from the surface and deeper waters. CO2 fluxes between atmosphere and ocean surface were estimated. Monsoon‐forced changes in the near‐surface carbonate system became clearly visible a few weeks after onset of the SW monsoon. Because of the upwelling of CO2‐rich waters along the Omani coast, DIC and pCO2 locally increased up to 2210 μmol kg−1 and 715 μatm, respectively. The Arabian Sea thus acted as a CO2 source during SW monsoon. Highest CO2 fluxes of >150 mmol m−2 d−1 were observed in the upwelling region off Oman, while the open Arabian Sea revealed relatively lower CO2 fluxes but contributed more to the overall CO2 release because of its larger area. Total CO2 emissions from the Arabian Sea from May until August 1997 are estimated to amount 67.6 Tg C. The upwelling−induced impacts of biological activity on the carbon cycle were estimated by tracing freshly upwelled water along its transport way along the sea surface. The obtained CO2 uptake by enhanced net community production (NCP) is ∼3.6 times higher than the CO2 emissions. In contrast to phosphate, upwelled nitrate apparently is consumed by NCP within a timescale of some 10 days, and the upwelling thus does not directly supply the central Arabian Sea with nitrate.
Changes in stream nitrate concentrations due to land management practices, ecological succession, and climate: Developing a systems approach to integrated catchment response
Authors: Worrall F. , Swank W. T. , Burt T. P.
Published: July 2003

This study uses time series analysis to examine long‐term stream water nitrate concentration records from a pair of forested catchments at the Coweeta Hydrologic Laboratory, North Carolina, USA. Monthly average concentrations were available from 1970 through 1997 for two forested catchments, one of which was clear‐felled in 1977 and the other maintained as a control. The time series were decomposed into their trend and annual cycle before modeling as an autoregressive (AR) process. AR models were calculated for both an expanding and a shifting window so that prefelling could be directly compared with the effects of tree clearance. In comparison with flow records for both of the catchments, transfer function‐noise models were calculated on a moving window basis, and the impulse functions were derived. Analysis shows that both catchments show an annual memory effect but that the clear‐felled catchment shows, in addition, a 6‐month memory effect. The annual effect in the control catchment responds to drought conditions while in the felled catchment, it reflects the change in vegetation. The 6‐month effect in the felled catchment responds to drought conditions independent of both the annual effect and of logging operations. The control catchment shows no significant impulse function with respect to flow, while for the felled catchment a distinct impulsivity develops over time subsequent to logging and coincident with the onset of nitrogen saturation. By examining the nature of the nitrate export, rather than solely the levels of export, a systems approach can be taken to understanding catchment behavior. Such an approach shows that the catchment is in metastable equilibrium with respect to its hydrological pathways and nitrogen reserves but in dynamic equilibrium with respect to long‐term temperature change. The onset of nitrogen saturation may represent irreversible changes in the catchment behavior, and impulsivity, with respect to streamflow, represents a new indicator of N‐saturated conditions.
Impact of underwater‐ice evolution on Arctic summer sea ice
Authors: Notz Dirk , McPhee Miles G. , Worster M. Grae , Maykut Gary A. , Schlünzen K. Heinke , Eicken Hajo
Published: July 2003

A model is presented that describes the simultaneous growth and ablation of a layer of ice between an under‐ice melt pond and the underlying ocean. Such “false bottoms” are the only significant source of ice formation in the Arctic during summer. Analytical solutions for diffusional transport of heat and salt are calculated that illustrate the importance of salt transport in effecting phase change. The model is extended to account for turbulent transports and applied to make predictions of bottom ablation rates of sea ice given the far‐field properties of the ocean from the AIDJEX and SHEBA field experiments. The model predictions show that false bottoms may play a significant role in the summer heat budget of the ice‐ocean system, causing localized heat fluxes of more than 10 W m−2 into the mixed layer. The thickening of thin ice by false‐bottom formation leads to longer‐lasting sea ice and thus smaller ice‐free areas, which might be an important mechanism affecting the surface albedo.
Surface precipitation electric current produced by convective rains during the Mesoscale Alpine Program
Authors: Soula S. , Chauzy S. , Chong M. , Coquillat S. , Georgis J. F. , Seity Y. , Tabary P.
Published: July 2003

This paper presents data from measurements of electric field, precipitation current density, and rainfall parameters performed during the Mesoscale Alpine Program experiment in northern Italy during autumn 1999. Several days of the period provided substantially charged rainfall of both polarities. The average proportions of each polarity are close, but the negative one is slightly larger (54%). Three Doppler radars provided a description of the cells' development and dynamics. A case of a deeply convective cell occurred on 17 September 1999. In this case, the precipitation current density is first positive, reaches more than 100 nA m−2, and changes its polarity when the rainfall is maximum with a value close to 200 mm h−1. We also consider several shallow convective cells passing over the experimental site on 3 October. Two cells among a set of eight did not produce electrical parameter variations although they displayed development and radar reflectivity structure similar to that of the others. The dynamical study shows that the vertical velocity (averaged over 1 km × 1 km mesh) was weaker within these two cells with a value of only 0.5 m s−1 while it reached 1.5 m s−1 within the other cells. Both charge polarities were observed on the rain produced by electrified cells, first the negative one and then the positive one. A very tight correlation between surface electric field and precipitation current is observed out at the surface, displaying the mirror image effect. The ground electric field is due to the cloud charge, in contrast with that carried down to the ground by the rainfall. In order to reproduce the field evolution created by the cell passage, we test different models of charge distribution. A model including a horizontal distribution is found to provide a field evolution in best agreement with the observations. According to this model the net charge of the cloud above the site is chronologically positive and negative, which can be the result of the evacuation of an opposite charge by the rain.
A new small drill hole minipermeameter probe for in situ permeability measurement: Fluid mechanics and geometrical factors
Authors: Dinwiddie Cynthia L. , Molz Fred J. , Castle James W.
Published: July 2003

Considerable heterogeneity is evident when permeability measurements are made on small scales, either in the field or in the laboratory on field samples. Small‐scale permeability measurements have commonly been made by inducing multidimensional gas flow through a sample with various configurations of the conventional surface‐sealing gas minipermeameter. In order to reduce weathering and seal‐quality problems, a new minipermeameter probe was designed for field application within small diameter holes drilled into an outcrop. We briefly describe the small drill hole minipermeameter, while developing in detail the associated data analysis methodology for performing in situ permeability measurements with this new probe. Analysis of field data, which consists of gas injection pressure and mass flow rate, is based on a numerical solution in cylindrical coordinates of the ideal gas flow equation, assuming homogeneous and isotropic conditions over the averaging volume of the measurements. In the following development the semianalytical inverse solution for permeability will be derived for the new small drill hole minipermeameter probe, which varies from that of the conventional surface‐sealing minipermeameter probe only in the choice of the appropriate characteristic length and in the magnitude of the associated geometrical factor.
Modeling the seismic signature of structural data from the Oman Ophiolite: Can a mantle diapir be detected beneath the East Pacific Rise?
Authors: Jousselin David , Dunn Robert , Toomey Douglas R.
Published: July 2003

We present modeling of the seismic delay time signature of mantle diapirs mapped in the Oman ophiolite and compare these results with those of active source seismic experiments conducted along the East Pacific Rise. To do so, we construct models of shallow‐mantle, seismic anisotropy that are consistent with Oman diapirs of different size. Forward calculations of the delay time anomalies due to a combination of diapir‐related seismic anisotropy and isotropic velocity structure are compared with those of a two‐dimensional anisotropy field within the same isotropic velocity structure. In the presence of an isotropic, low‐velocity anomaly comparable to that imaged beneath the East Pacific Rise, there are only minor differences between the predicted signals of two‐ and three‐dimensional (diapiric) flow. Tomographic modeling is used to determine if the synthetic data for a diapiric model (with a low‐velocity isotropic anomaly) can be fit by two‐dimensional anisotropy and three‐dimensional velocity variations. The recovered isotropic anomalies are in good agreement with the synthetic model. However, if the diapir is large enough, artifacts are generated near the corners of the model and, locally, at the ridge axis, with slightly higher velocities. Our results indicate that tomographic analyses of existing travel time data from the East Pacific Rise cannot be used to rule out the presence of diapirs beneath an active spreading center if they are similar in scale to those mapped in Oman.
Environmental controls on the stable isotopic composition of Mercenaria mercenaria: Potential application to paleoenvironmental studies
Authors: Elliot Mary , deMenocal Peter B. , Linsley Braddock K. , Howe Stephen S.
Published: July 2003

We have investigated the environmental controls of seasonally resolved records of oxygen and carbon isotopes of modern Mercenaria mercenaria bivalves collected live from five coastal sites along the east coast of North America. Seasonal profiles of δ18O and δ13C obtained by subsampling the incremental growth layers of aragonite were compared with in situ historical records of temperature and salinity. We show that M. mercenaria δ18O profiles track accurately the seasonal variations of water temperature and that variations in growth rates do not affect the shell δ18O values. Growth rates are strongly reduced or interrupted below water temperatures ranging from 8 to 10°C, implying that only bivalves sampled in tropical areas track the full amplitude of seasonal variations. Although further measurements of water δ18O and a better understanding of seasonal variations of the water δ18O‐salinity relationships are necessary, Mercenaria mercenaria bivalves appear to precipitate their shell close to isotopic equilibrium. Whereas the amplitude of the seasonal profiles of δ18O reflects variations in water temperature, the annual average δ18O decreases with latitude, reflecting the trend of rainfall and riverwater δ18O with latitude over the Northern American continent.
Low‐pressure phase equilibria of anhydrous anorthite‐bearing mafic magmas
Authors: Kohut Edward J. , Nielsen Roger L.
Published: July 2003

One of the most persistent questions regarding the phase equilibria of mid‐ocean ridge basalts (MORB) pertains to the petrogenesis of the anorthitic plagioclase phenocrysts (>An90) that are characteristic of the more primitive members of such suites. Anorthitic phenocrysts are present in many if not most MORB suites in spite of the fact that no naturally occurring MORB glasses have ever been discovered to be in equilibrium with plagioclase more calcic than An85. We have addressed this paradox by attempting to saturate natural basalts with anorthite in a series of 1 atm experiments using three different natural basaltic starting compositions: an N‐MORB, an E‐MORB, and a continental high‐alumina basalt. To ensure duplication of the olivine and anorthite saturation observed in natural anorthite‐bearing basalt, the experiments were run in An93‐6 capsules with Fo92 olivine added to the starting glass. The compositions of experimental liquids are generally colinear with the trends observed in the lava suites used as the source material for the starting glasses. Significantly, aluminous spinel (Al2O3 contents of 61–68 wt%) was produced at 1290°C in all compositions and chromites (Al2O3 contents of 33–42 wt%) at lower temperatures in N‐MORB‐derived liquids despite no spinel having been added to the starting mixture. In addition, the experiments produced basaltic liquid in equilibrium with both >Fo89 olivine and >An85 feldspar at temperatures of 1230° and 1210°. These liquids have compositions with Mg# (at% Mg/Mg + FeT*100) that range from 63 to >85. The TiO2‐MgO correlation indicates large (∼16–23%) amounts of crystallization for each percent decrease in MgO. These results suggest the possibility that dry, anorthite‐bearing basaltic magmas are the product of the interaction between primary melt and Al‐spinel‐bearing upper mantle. In addition, the results indicate that MORB magmas can undergo a large amount (>50%) of crystallization prior to reaching 8% MgO. Further, although anorthite‐bearing magmas have characteristics consistent with their being a significant volumetric component of MORB “parent” magmas, the reaction mechanism suggested for their petrogenesis indicates that they are not necessarily primary magmas.
Peridotites and gabbros from the Parece Vela backarc basin: Unique tectonic window in an extinct backarc spreading ridge
Authors: Ohara Yasuhiko , Fujioka Kantaro , Ishii Teruaki , Yurimoto Hisayoshi
Published: July 2003

Peridotite samples from a backarc basin setting will help better understand global mid‐oceanic ridge processes. Here we report detailed petrological data of serpentinized peridotite and gabbro from the extinct Parece Vela Basin in the Philippine Sea. Despite its relatively fast spreading rate (8.8–7.0 cm/y full‐rate), the Parece Vela Basin spreading ridge (the Parece Vela Rift) has the distinct morpho‐tectonic characteristics that indicate a small degree of mantle melting, including the presence of a huge mullion structure (the Godzilla Mullion). Peridotites in the Parece Vela Rift are exposed on the Godzilla Mullion as well as at a segment midpoint. The most notable characteristic of Parece Vela Rift peridotites is small‐scale juxtaposition (i.e., a single‐dredge‐haul scale) of fertile peridotite and depleted peridotite (dunite and plagioclase‐bearing peridotite). We interpret that the fertile peridotite (F‐type) is the residue of a small degree of mantle melting (∼4% near‐fractional melting of a MORB‐type mantle), whereas dunite (D‐type) and plagioclase‐bearing peridotite (P‐type) are products of melt‐mantle interaction. The associated evolved gabbros may represent the shallow level fractionated melt intruded into P‐type. The distinct morpho‐tectonic characteristics, peridotite exposure at a segment midpoint, and the presence of fertile peridotite may result from an extreme transform fault effect caused by the ridge‐transform geometry of short first‐order segments sandwiched by closely spaced fracture zones (“transform sandwich effect”).
Principal modes of variability of Martian atmospheric surface pressure
Authors: Leroy S. S. , Yung Y. L. , Richardson M. I. , Wilson R. J.
Published: July 2003

An analysis of daily‐to‐interannual variability in the surface pressure field of the Martian nothern hemisphere as given by a Martian climate model is presented. In an empirical orthogonal function (EOF) decomposition, the dominant first two modes of variability comprise a zonal wavenumber 1 feature centered at 70 N latitude moving eastward with a period of 6 to 8 sols. This feature is a baroclinic wave and accounts for 53% of the northern hemisphere non‐stationary surface pressure variability, and, when active, has an amplitude of up to 2% of local surface pressure. The third mode of the EOF decomposition is annular about the Martian north pole, is null southward of 70 N, and accounts for 7% of the northern hemisphere non‐stationary surface pressure variability. The baroclinic wave (EOFs 1 & 2) is active during northern hemisphere winter and spring, consistent with models of the Martian atmospheric circulation, and the annular mode (EOF 3) is active only at the onset and demise of the baroclinic feature. When active, it is not uncommon for the annular mode to reside in either its positive or negative state stably for 20 to 30 sols. It is postulated that baroclinic waves with longitudinal wavenumber 2, 3, and 4 act as a pump for the annular mode. The annular mode should not be present in MGS TES data.
Arc composition at mid‐crustal depths: Insights from the Coast Ridge Belt, Santa Lucia Mountains, California
Authors: Ducea Mihai N. , Kidder Steven , Zandt George
Published: July 2003

The Coast Ridge Belt (CRB, Santa Lucia Mts., central California) comprises mid‐crustal rocks (750–800°C and 0.8 GPa) of the California magmatic arc. We estimated the bulk composition of the CRB and converted our results to seismic velocities expected at the observed pressures and temperatures. This transformation allows us to compare calculated velocities for the CRB with in situ measurements in similar arcs. The bulk composition of this arc section changes abruptly at 25 km depth from a granodiorite to a quartz‐diorite or diorite. These data are in agreement with geophysical results from other Cordilleran batholiths, and suggest 1.5 to 2 times thicker felsic columns than usually interpreted for modern continental arcs, and a relatively sharp transition between a felsic upper crustal batholith, and a mafic deep crust. This implied rheological boundary may have significant implications for intracrustal faulting or convective removal of the roots of batholiths.
An interplanetary cause of large geomagnetic storms: Fast forward shock overtaking preceding magnetic cloud
Authors: Wang Y. M. , Ye P. Z. , Wang S. , Xue X. H.
Published: July 2003

In the event that occurred during October 3–6, 2000, at least one magnetosonic wave and one fast forward shock advanced into the preceding magnetic cloud (MC). By using the field and plasma data from the ACE and WIND spacecraft, we analyze the evolution of this event, including the characteristics and changes of the magnetic fields and plasma. At the rear part of the cloud, a large southward magnetic field is caused by a shock compression. The shock intensified a preexisting southward magnetic field. This increased the geoeffectiveness of this event and produced an intense geomagnetic storm with Dst = −175 nT. We also describe another event with a shock overtaking a MC on Nov. 6, 2001. A great geomagnetic storm of intensity Dst = 292 nT resulted. These observations are used to argue that shock compression of magnetic cloud fields is an important interplanetary cause of large geomagnetic storms. Our analyses suggest that the geoeffectiveness is related to the direction of preexisting magnetic fields, the intensity of overtaking shock, and the amount of shock penetration into the preceding MC.
Interannual oscillations in length of day: Implications for the structure of the mantle and core
Authors: Mound J. E. , Buffett B. A.
Published: July 2003

An ∼6‐year variation in the length of day has been observed for which there is no corresponding signal in records of atmospheric angular momentum. We find that this signal can be explained by an exchange of angular momentum with the core arising from gravitational coupling between the mantle and inner core. We develop a theoretical model of the core‐mantle system that includes a combination of gravitational and electromagnetic couplings that allow angular momentum to be transferred between the solid inner core, fluid outer core, and mantle of the Earth. This model is used to calculate the natural period of interannual oscillations in the axial rotation of the core and mantle. The period and quality of the free oscillations depend on physical properties of the core and mantle. Time‐varying geodynamo processes produce torques on the inner core which are capable of exciting the predicted free oscillations to observable levels. The observed length‐of‐day variation is used to constrain the strength of gravitational coupling between the mantle and inner core and hence the degree 2, order 2 component of equipotential surfaces at the inner core boundary and core mantle boundary. This constraint has implications for models of mantle flow.
Stromboli volcano (Aeolian Archipelago, Italy): An open window on the deep‐feeding system of a steady state basaltic volcano
Authors: Bertagnini A. , Métrich N. , Landi P. , Rosi M.
Published: July 2003

Paroxysms at Stromboli are the most violent manifestations of the persistent activity and are related to the emission of small volumes (103–105 m3) of nearly aphyric HK‐basaltic pumices. They offer the exceptional opportunity to detail the mixing‐crystallization‐degassing processes that occur in a steady state basaltic arc volcano. We present mineralogy, major, volatile, and trace element geochemistry of olivine‐hosted melt inclusions of these pumices. In all the paroxysms, melt inclusions hosted in olivines Fo88–91 have recorded the parental melts rich in CaO (up to 14.5 wt %) but low in FeO (6–7 wt %). They demonstrate recurrent variations in the K2O content (1.6–1.3 wt %) and S/Cl ratios (1.2–0.8) of the melts that entered the deep system. Dynamic magma mixing between melts slightly distinct by their degree of evolution, rapid crystallization, and entrapment of gas‐oversaturated melts during decompression are indicated by (1) the high density of irregular, clear melt inclusions, and embayments in homogeneous olivines (Fo87±0.5–Fo83±0.5), (2) the variable ratio between melt and gas bubble, and (3) the variability of melt inclusion compositions in both major (CaO/Al2O3 = 1–0.59) and volatile (3.4–1.8 wt % H2O, 1582–1017 ppm CO2) elements. FeO‐rich melt inclusions in patchy, reversely zoned olivines also demonstrate interactions between ascending melt blobs and inherited olivine crystals. We propose a model involving a vertically extended dike‐like system, where magmas progress and differentiate. On the basis of olivine growth rate calculations the volatile‐rich magma blobs may ascend within few hours to few tenths of hours. Finally, we propose that sulfur degassing is possibly initiated during the early stage of magma differentiation.
A yearlong comparison of plot‐scale and satellite footprint‐scale 19 and 37 GHz brightness of the Alaskan North Slope
Authors: Kim E. J. , England A. W.
Published: July 2003

Subpixel heterogeneity remains a key issue in the estimation of land parameters using satellite passive microwave sensors; the scales of spatial variability on land are typically much smaller than sensor footprints (tens of km). Disaggregation is a necessary component of any successful assimilation or retrieval scheme attempting to exploit satellite passive microwave observations to estimate parameters at the local scale. This paper quantifies the similarity between ground‐based brightness and satellite brightness observations at 19 and 37 GHz for Arctic tundra on the North Slope of Alaska, identifying and quantifying sources of the differences. To the extent that this very homogeneous area represents a limiting case, the impact of subpixel heterogeneity in less homogeneous areas may be gauged. The ground‐based radiobrightness observations were collected during the Radiobrightness Energy Balance Experiment 3 (REBEX‐3) conducted on the North Slope in 1994–1995. A comparison was made of 381 days of brightness observations from a tower‐mounted Special Sensor Microwave Imager (SSM/I) simulator representing the full range of annual conditions with coincident satellite SSM/I observations. Issues such as instrument stability, the effects of atmospheric radiative transfer, and consistency of satellite pixel locations are considered. Linear correlations between tower‐based and SSM/I brightness observations of 0.93, 0.94, 0.93, and 0.92 were observed for the 19V, 19H, 37V, and 37H channels, respectively. Footprint sizes were 2 × 4 m for the tower‐based observations and 43 × 69 km for the resampled SSM/I observations. Atmospheric, topographic, and time‐of‐observation effects can account for the differences between the best fit lines and the 1:1 lines, with calibration errors accounting for the residual differences.
Comparison of size and morphological measurements of coarse mode dust particles from Africa
Authors: Reid Jeffrey S. , Jonsson Halflidi H. , Maring Hal B. , Smirnov Alexander , Savoie Dennis L. , Cliff Steven S. , Reid Elizabeth A. , Livingston John M. , Meier Mike M. , Dubovik Oleg , Tsay Si‐Chee
Published: July 2003

A multitude of sensitivity studies in the literature point to the importance of proper chemical and morphological characterization of particles when the radiative impacts of airborne dusts are modeled. However, the community data set is based on heterogeneous measurement methods relying on varying aerodynamic, chemical, morphological, and optical means. During the Puerto Rico Dust Experiment, size distributions of dust particles from Africa were measured using a variety of aerodynamic, optical, and geometric means. Consistent with the literature, comparisons of these size distributions showed quite dissimilar results. “Measured” volume median diameters varied from 2.5 to 9 μm for various geometric, aerodynamic, optical, and optical inversion methods. Aerodynamic systems showed mixed performance. Column integrated size distributions inverted from AERONET Sun/sky radiance data produced somewhat reasonable results in the coarse mode when given proper constraints and taken in the proper context. The largest systematic errors were found in optical particle counters due to insensitivities to particle size in the 4–10 μm region with further complications due to dust particle morphology and index of refraction issues. As these methods can produce quite dissimilar size distributions, considerable errors in calculated radiative properties can occur if incorrectly modeled into dust parameters. None of the methods compared in this study can adequately reproduce the measured mass extinction or mass scattering efficiency of the dust using spherical geometry methods. Given all of the uncertainties in the sizing methods, we promote the use of fundamental and quantifiable descriptors of particles such as mass as a function of aerodynamic diameter.