bluuebunny/crossref_metadata_2025 huggingface dataset:
Racial differences in cervical cancer survival in the Detroit metropolitan area
Authors: Movva Sujana , Noone Anne‐Michelle , Banerjee Mousumi , Patel Divya A. , Schwartz Kendra , Yee Cecilia L. , Simon Michael S.
Published: February 2008

BACKGROUND

African‐American (AA) women have lower survival rates from cervical cancer compared with white women. The objective of this study was to examine the influence of socioeconomic status (SES) and other variables on racial disparities in overall survival among women with invasive cervical cancer.

METHODS

One thousand thirty‐six women (705 white women and 331 AA women) who were diagnosed with primary invasive cancer of the cervix between 1988 and 1992 were identified through the Metropolitan Detroit Cancer Surveillance System (MDCSS), a registry in the Surveillance, Epidemiology, and End Results (SEER) database. Pathology, treatment, and survival data were obtained through SEER. SES was categorized by using occupation, poverty, and educational status at the census tract level. Cox proportional hazards models were used to compare overall survival between AA women and white women adjusting for sociodemographics, clinical presentation, and treatment.

RESULTS

AA women were more likely to present at an older age (P < .001), with later stage disease (P < .001), and with squamous histology (P = .01), and they were more likely to reside in a census tract categorized as Working Poor (WP) (P < .001). After multivariate adjustment, race no longer had a significant impact on survival. Women who resided in a WP census tract had a higher risk of death than women from a Professional census tract (P = .05). There was a significant interaction between disease stage and time with the effect of stage on survival attenuated after 6 years.

CONCLUSIONS

In this study, factors that affected access to medical care appeared to have a more important influence than race on the long‐term survival of women with invasive cervical cancer. Cancer 2008. © 2008 American Cancer Society.
Cognitive–behavioural, pharmacological and psychosocial predictors of outcome during tapered discontinuation of benzodiazepine
Authors: O'Connor Kieron , Marchand André , Brousseau Lucie , Aardema Frederick , Mainguy Nicole , Landry Pierre , Savard Pierre , Léveillé Cathy , Lafrance Valérie , Boivin Sonia , Pitre Denise , Robillard Sophie , Bouthillier Donald
Published: February 2008

Eighty‐six participants wishing to stop benzodiazepine and who met DSM‐IV (Diagnostic and Statistical Manual of Mental Disorders, 4th ed. American Psychological Association, 1994) criteria for anxiety disorder or insomnia were assessed pre‐ and post‐taper on clinical, pharmacological and psychosocial measures. An initial cohort of 41 participants received treatment as usual (taper only) plus physician counselling in the same clinic setting. A second cohort of 45 participants were randomly allocated to group cognitive–behavioural therapy (CBT) plus taper, or group support (GS) plus taper. At 3 months follow‐up, the outcomes in both the CBT and the GS subgroups were equivalent. Intention to treat analysis revealed a slight advantage to the CBT over the GS group and the CBT group showed higher self‐efficacy post‐taper.

Over all 86 participants, a high‐baseline level of psychological distress, anxiety and dosage predicted a poor outcome, but increase in self‐efficacy contributed to a successful outcome particularly in those with initially poor baseline predictors. Although there was a decrease in positive affect during preliminary stages of tapered discontinuation compared to baseline, there was no significant overall increase in negative affect. Copyright © 2008 John Wiley & Sons, Ltd.
The use of mindfulness in obsessive compulsive disorder: suggestions for its application and integration in existing treatment
Authors: Fairfax Hamilton
Published: February 2008

Treatment for obsessive–compulsive disorder (OCD) is a standard activity of psychologists, particularly those in Community Mental Health Teams (CMHT). In 2005, NICE published guidelines recommending Cognitive Behavioural Therapy (CBT) with Exposure and Response Prevention (ER‐P) as the evidence‐based psychological treatments of choice. In recent years there have been significant developments within cognitive behavioural theory, including what has been referred to as the ‘Third Wave’. This paper explores the contribution of mindfulness; a practice that has previously been integrated into other CBT models of treatment, to cognitive interventions in OCD, suggesting that in complements both CBT and ER—However it had previously been suggested by Freeston that mindfulness may prevent successful ER‐P by becoming a neutralising technique. Examples of the application of a mindfulness‐based approach are explored (MOCD), including reference to an OCD group run by the author, and areas of potential overlap are identified, in particular thought‐action Fusion. It is concluded that if applied properly, mindfulness not only complements traditional CBT interventions, but could also increase their efficacy and perhaps prevent relapse. Copyright © 2008 John Wiley & Sons, Ltd.
Treatment of child anxiety: an exploratory study of the role of maternal anxiety and behaviours in treatment outcome
Authors: Creswell Cathy , Willetts Lucy , Murray Lynne , Singhal Meghna , Cooper Peter
Published: February 2008

Anxiety disorders are common among parents of anxious children and have been found to impede child treatment outcomes, yet it is unclear whether it is parental anxiety that needs to be targeted in therapy or associated parental behaviours. Twenty‐two children (6–12 years) with a current anxiety disorder and their mothers received cognitive–behavioural treatment (CBT) for child anxiety. In addition, of the 12 mothers who met criteria for a current anxiety disorder, 6 received CBT for their own disorder. Assessments were made of the mother–child interaction. The main findings were: (1) children did less well from treatment where their mothers had a current anxiety disorder; (2) treatment of maternal anxiety disorder did not improve child treatment outcome; and (3) maternal overinvolvement and expression of fear was associated with child treatment outcome. The results suggest that in the context of maternal anxiety disorder, child treatment outcome may be improved by specifically targeting parenting behaviours. Copyright © 2008 John Wiley & Sons, Ltd.
A Cre transgene active in developing endodermal organs, heart, limb, and extra‐ocular muscle
Authors: Grieshammer Uta , Agarwal Pooja , Martin Gail R.
Published: February 2008

Cre‐mediated recombination, a method widely used in mice for tissue‐specific inactivation of endogenous genes or activation of transgenes, is critically dependent on the availability of mouse lines in which Cre recombinase functions in the tissue of interest or its progenitors. Here we describe a transgenic mouse line, Osr1‐cre, in which Cre is active from embryonic day (E)11.5 in a few specific tissues. These include the endoderm of the posterior foregut, midgut, hindgut, and developing urogenital system, the heart left atrium, extra‐ocular muscle progenitors, and mesenchyme in particular regions of the limb. Furthermore, starting at E12.5, Cre functions in limb interdigital mesenchyme. Within the urogenital system, recombination appears to be virtually complete in the epithelium of the bladder and urethra just posterior to it by E14.5. In males, some of these urethral cells form the prostate. The spatiotemporal pattern of Cre activity in Osr1‐cre makes it a unique resource among the lines available for Cre‐mediated recombination experiments. genesis 46:69–73, 2008. © 2008 Wiley‐Liss, Inc.
Tissue‐specific expression of Cre recombinase from the Tgfb3 locus
Authors: Yang Liang‐Tung , Li Wai‐Yee , Kaartinen Vesa
Published: February 2008

Tgfb3, a member of the TGF‐β superfamily, is tightly regulated, both spatially and temporally, during embryogenesis. Previous mouse knockout studies have demonstrated that Tgfb3 is absolutely required for normal palatal fusion and pulmonary development. We have generated a novel tool to ablate genes in Tgfb3‐expressing cells by targeting the promoterless Cre‐pgk‐Neo cassette into exon 1 of the mouse Tgfb3 gene, which generates a functionally null Tgfb3 allele. Using the Rosa26 reporter assay, we demonstrate that Cre‐induced recombination was already induced at embryonal day 10 (E10) in the ventricular myocardium, limb buds, and otic vesicles. At E14, robust recombination was detected in the prefusion palatal epithelium. Deletion of the TGF‐β type I receptor Alk5 (Tgfbr1) specifically in Tgfb3 expressing cells using the Tgfb3‐Cre driver line lead to a cleft palate phenotype similar to that seen in conventional Tgfb3 null mutants. In addition, Alk5/ Tgfb3‐Cre mice displayed hydrocephalus, and severe intracranial bleeding due to germinal matrix hemorrhage. genesis 46:112–118, 2008. © 2008 Wiley‐Liss, Inc.
Influence of the Diketonato Ligand on the Cytotoxicities of [Ru(η6‐p‐cymene)(R2acac)(PTA)]+ Complexes (PTA = 1,3,5‐triaza‐7‐phosphaadamantane)
Authors: Vock Carsten A. , Renfrew Anna K. , Scopelliti Rosario , Juillerat‐Jeanneret Lucienne , Dyson Paul J.
Published: February 2008

A series of compounds of general formula [Ru(η6‐p‐cymene)(R2acac)(PTA)][X] (R2acac = Me2acac, tBu2acac, Ph2acac, Me2acac‐Cl; PTA = 1,3,5‐triaza‐7‐phosphaadamantane; X = BPh4, BF4), and the precursor to the Me2acac‐Cl derivative [Ru(η6‐p‐cymene)(Me2acac‐Cl)Cl], have been prepared and characterised spectroscopically. Five of the compounds have also been characterised in the solid state by X‐ray crystallography. The tetrafluoroborate salts are water‐soluble, quite resistant to hydrolysis, and have been evaluated for cytotoxicity against A549 lung carcinoma and A2780 human ovarian cancer cells. The compounds are cytotoxic towards the latter cell line, and relative activities are discussed in terms of hydrolysis (less important) and lipophilicity, which appears to exert the dominating influence. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
How a major multinational is working to overcome the barriers to improved expatriate ROI
Authors: McNulty Yvonne
Published: February 2008

Despite the growing use of international assignments and the high cost of expatriates, few global firms have found the key to gauging the success of their mobility program, especially their expatriate return on investment (ROI). The author reports on one global firm that has made great strides towards a practical ROI tool by targeting the fundamental systems and processes needed to manage international assignments. The author also makes the case that an assignment's purpose, relative to business and/or organizational strategies, determines the types of inputs and outcomes to measure; and that ROI determinations for expatriates must include intangible and long‐term benefits and costs. © 2008 Wiley Periodicals, Inc.
Mechanical properties of auxetic tubular truss‐like structures
Authors: Scarpa F. , Smith C. W. , Ruzzene M. , Wadee M. K.
Published: February 2008

The mechanical properties of cellular tubular structures made of centresymmetric cells are evaluated using analytical and numerical simulations. A theoretical model based on bending stiffness of the single ribs composing the unit cell of the tubes is developed, providing estimations for the Poisson's ratios and uniaxial stiffness of the tubular grid‐like structures, as well as their Eulerian buckling load. Full 3D Finite Element models in linear elastic regime are used to validate the theoretical results. A continuum nonlinear tube bending model is also presented to show the dependence of the curvature‐bending moment versus the Poisson's ratio of the core. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Monte Carlo approach for change‐point detection in the Cox proportional hazards model
Authors: Liu Mengling , Lu Wenbin , Shao Yongzhao
Published: February 2008

Detecting a time lag of treatment effect or identifying change points in a hazard function is of great interest and importance in survival analysis. The testing procedures hereto are primarily based on analytical approximations for the asymptotic null distribution of either the likelihood ratio test or the score test. In the presence of random censoring and/or covariates, however, the justification for the limiting distribution often requires some technical assumptions and conditions that are difficult to verify in practice. Moreover, a satisfactory asymptotic theory for testing the existence of multiple change points in hazard function has not emerged. In this paper, we consider maximal score tests for detecting change point(s) in the Cox proportional hazards model with censored data. We propose to use a simple Monte Carlo approach for assessing the statistical significance of tests. The proposed approach is applicable for testing a single change point in the Cox model with covariates and sample stratifications over various types of candidate regions, including discrete time‐point sets or disjoint intervals. We also show that the proposed test statistics and the Monte Carlo procedure are well applicable under situations with multiple change points. Simulation studies and an analysis of a real data from a randomized cancer trial are conducted to demonstrate the finite‐sample performance of the proposed approach. Copyright © 2008 John Wiley & Sons, Ltd.
Quantification of Pentafluorobenzyl Oxime Derivatives of Long Chain Aldehydes by GC–MS Analysis
Authors: Brahmbhatt Viral V. , Nold Christopher , Albert Carolyn J. , Ford David A.
Published: February 2008

Negative ion mass spectrometric techniques, for compounds having good ionization properties, such as pentafluorobenzyl derivatives, are believed to be more sensitive than positive ion methods. Preparation of PFB oximes of fatty aldehydes from crude lipid extracts is problematic due to the release of free aldehydes from plasmalogens during derivatization. Accordingly, in these studies plasmalogens were removed by silicic acid column chromatography prior to pentafluorobenzyl derivatization. This simple purification step to remove plasmalogens is shown to facilitate the quantification of long‐chain aldehydes by analysis of their pentafluorobenzyl oxime derivatives utilizing gas chromatography–mass spectrometry in the negative ion chemical ionization mode. The limit of detection for long chain fatty aldehydes using this method is 0.5 pmol and it is linear over two orders of magnitude. Silicic acid column chromatography followed by electrospray ionization mass spectrometry demonstrated that plasmalogens were removed (the detection limit for this analyses was ≤0.3 pmol). Furthermore, we have exploited the utility and sensitivity of this method to identify increases in hexadecanal and octadecanal in 3‐amino‐1,2,4‐triazole treated human neutrophils.
Destabilization of the Emulsion Formed during Aqueous Extraction of Soybean Oil
Authors: Morales Chabrand Ramón , Kim Hyun‐Jung , Zhang Cheng , Glatz Charles E. , Jung Stephanie
Published: February 2008

Characterization and destabilization of the emulsion formed during aqueous extraction of oil from soybean flour were investigated. This emulsion was collected as a cream layer and was subjected to various single and combined treatments, including thermal treatments and enzymatic treatments, aimed at recovery of free oil. The soybean oil emulsion formed during the aqueous extraction processing of full fat flour contains high molecular weight glycinin and β‐conglycinin proteins and smaller oleosin proteins, which form a multilayer interface. Heat treatment alone did not modify the free oil recovery but freeze–thaw treatment increased the oil yield from 3 to 22%. After enzymatic treatment of the emulsion, its mean droplet size changed from 5 to 14 μm and the oil recovery increased to 23%. This increase could be attributed to the removal (due to enzymatic hydrolysis) of large molecular weight polypeptides from the emulsion interface, resulting in partial emulsion destabilization. When enzymatic treatment was followed by a freeze–thaw step, the oil recovery increased to 46%. This result can be attributed to the thinner interfacial membrane after enzymatic hydrolysis, partial coalescence during freeze–thaw, and coalescence during centrifugation. Despite the reduction in emulsion stability achieved, additional demulsification approaches need to be pursued to obtain an acceptably high conversion to free oil.
Primary early correction of tetralogy of Fallot irrespective of age
Authors: Kantorova Andrea , Zbieranek Kai , Sauer Henning , Lilje Christian , Haun Christoph , Hraska Viktor
Published: February 2008

Objective

The policy of early repair of patients with tetralogy of Fallot, irrespective of age, as opposed to initial palliation with a shunt, remains controversial. The aim of our study was to analyze the midterm outcome of primary early correction of tetralogy of Fallot.

Methods

Between 1996 and 2005, a total of 61 consecutive patients less than 6 months of age underwent primary correction of tetralogy of Fallot in two institutions. The median age at surgery was 3.3 months, and 27 patients (44%) were younger than 3 months of age, including 12 (20%) newborns. We analyzed the patients in 2 groups: those younger than 3 months of age, and those aged between 3 and 6 months.

Results

There was one early (1.6%), and one late death. Actuarial survival was 98.4%, 96.7%, 96.7% at 1, 5, and 10 years respectively, with a median follow up of 4.5 years. There was no difference in survival, bypass time, lengths of ventilation, and hospital stay between the groups. A transjunctional patch was placed significantly more often in the patients younger than 3 months (p = 0.039), with no adverse effect on survival and morbidity during the follow-up. Freedom from reoperation was 98.2%, 92.2%, and 83% at 1, 5, and 10 years respectively, with no difference between the groups.

Conclusion

Elective primary repair of tetralogy of Fallot in asymptomatic patients is delayed beyond 3 months of age. In symptomatic patients, primary repair of tetralogy of Fallot is performed irrespective of age, weight and preoperative state. This approach is safe, and provides an excellent midterm outcome with acceptable morbidity and rates of reintervention. The long-term benefits of this approach must be established by careful follow-up, with particular emphasis on arrhythmias, right ventricular function, and exercise performance.
Arctic late Paleocene–early Eocene paleoenvironments with special emphasis on the Paleocene‐Eocene thermal maximum (Lomonosov Ridge, Integrated Ocean Drilling Program Expedition 302)
Authors: Sluijs Appy , Röhl Ursula , Schouten Stefan , Brumsack Hans‐J. , Sangiorgi Francesca , Sinninghe Damsté Jaap S. , Brinkhuis Henk
Published: February 2008

We reconstruct the latest Paleocene and early Eocene (∼57–50 Ma) environmental trends in the Arctic Ocean and focus on the Paleocene‐Eocene thermal maximum (PETM) (∼55 Ma), using strata recovered from the Lomonosov Ridge by the Integrated Ocean Drilling Program Expedition 302. The Lomonosov Ridge was still partially subaerial during the latest Paleocene and earliest Eocene and gradually subsided during the early Eocene. Organic dinoflagellate cyst (dinocyst) assemblages point to brackish and productive surface waters throughout the latest Paleocene and early Eocene. Dinocyst assemblages are cosmopolitan during this time interval, suggesting warm conditions, which is corroborated by TEX86′‐reconstructed temperatures of 15°–18°C. Inorganic geochemistry generally reflects reducing conditions within the sediment and euxinic conditions during the upper lower Eocene. Spectral analysis reveals that the cyclicity, recorded in X‐ray fluorescence scanning Fe data from close to Eocene thermal maximum 2 (∼53 Ma, presence confirmed by dinocyst stratigraphy), is related to precession. Within the lower part of the PETM, proxy records indicate enhanced weathering, runoff, anoxia, and productivity along with sea level rise. On the basis of total organic carbon content and variations in sediment accumulation rates, excess organic carbon burial in the Arctic Ocean appears to have contributed significantly to the sequestration of injected carbon during the PETM.
Calculation of aerosol backscatter from airborne continuous wave focused CO2 Doppler lidar measurements: 1. Algorithm description
Authors: Rothermel Jeffry , Bowdle David A. , Vaughan J. Michael , Brown Derek W. , Woodfield Alan A.
Published: February 2008

Since 1981 the Royal Signals and Radar Establishment and the Royal Aircraft Establishment, United Kingdom, have made vertical and horizontal sounding measurements of aerosol backscatter coefficients at 10.6 μm using an airborne continuous wave focused CO2 Doppler lidar, the Laser True Airspeed System (LATAS). The heterodyne signal from the LATAS detector is spectrally analyzed. Then, in conjunction with aircraft flight parameters, the data are processed in a six‐stage computer algorithm: set search window, search for peak signal, test peak signal, measure total signal, calculate signal‐to‐noise ratio (SNR), and calculate backscatter coefficient.
The simplified exchange method revisited: An accurate, rapid method for computation of infrared cooling rates and fluxes
Authors: Schwarzkopf M. Daniel , Fels Stephen B.
Published: February 2008

The performance and construction of a new algorithm for the calculation of infrared cooling rates and fluxes in terrestrial general circulation models are described in detail. The computational method, which is suitable for use in models of both the troposphere and the middle atmosphere, incorporates effects now known to be important, such as an extended water vapor e‐type continuum, careful treatment of water vapor lines, of water‐carbon dioxide overlap, and of Voigt line shape. The competing requirements of accuracy and speed are both satisfied by extensive use of a generalization of the simplified exchange approximation of Fels and Schwarzkopf (1975). Cooling rates and fluxes are validated by comparison with benchmark line‐by‐line calculations on standard atmospheric profiles obtained for the Intercomparison of Radiation Codes Used in Climate Models (ICRCCM). Results indicate that the new algorithm is substantially more accurate than any previously used at the Geophysical Fluid Dynamics Laboratory.
Auroral effects on midlatitude semidiurnal tides
Authors: Fesen C. G. , Richmond A. D. , Roble R. G.
Published: February 2008

The effect of auroral activity on mid‐latitude semidiurnal tides was investigated using simulations from the NCAR Thermosphere/Ionosphere General Circulation Model (TIGCM). Model runs were made for solar cycle minimum equinox conditions for four levels of geomagnetic activity parameterized by the total hemispheric power index and the cross polar cap potential drop. Simulations at 42.5°N (gg) predicted that the upper thermosphere semidiurnal winds and temperatures generally increase with increasing geomagnetic activity, while the lower thermosphere fields were relatively insensitive to the level of auroral forcing in the model. The modelled semidiurnal mid‐latitude tidal response was determined by the magnitude and phasing of the waves generated by in situ solar forcing and the auroral momentum and energy sources, in conjunction with those propagating up from the lower atmosphere. The predicted sensitivity of the model tides to the level of geomagnetic activity may contribute to the observed tidal variability at mid latitudes. Successful modelling of observations will require careful specification of the high‐latitude energy and momentum sources.
Comet simulation experiments as a prelude to the CRAF and Rosetta missions
Authors: Bar‐Nun Akiva
Published: February 2008

Some of the achievements of small scale comet simulation experiments and modelling are described, which led to a need of large scale simulation experiments such as KOSI. As part of the KOSI effort, a new machine is being built at Tel Aviv University to produce large samples of gas‐laden amorphous water ice. These large scale experiments are a preparation for the coming CRAF and ROSETTA missions to comets.
Plasma wave generation near the inner heliospheric shock
Authors: Macek W. M. , Cairns I. H. , Kurth W. S. , Gurnett D. A.
Published: February 2008

There is mounting evidence that the Voyager 1 and 2 and Pioneer 11 spacecraft may approach the inner (termination) heliospheric shock near the end of this century. It is argued here, by analogy with planetary bow shocks, that energetic electrons backstreaming from the heliospheric shock along the magnetic field should be unstable to the generation of Langmuir waves by the electron beam instability. Analytic expressions for the cutoff velocity, corresponding to the beam speed of the electrons backstreaming from the shock, are derived for a standard solar wind model. At the front side of the heliosphere the maximum beam velocity is expected to be at the meridian passing through the nose of the shock, which is assumed aligned with the Very Local Inter‐Stellar Medium (VLISM) flow. This foreshock region and the associated Langmuir waves are relevant to both the expected in situ observations of the heliospheric boundaries, and to the low‐frequency (2–3 kHz) radio emissions observed by the Voyager spacecraft in the outer heliosphere. Provided that these radio emissions are generated by Langmuir waves, the minimum Langmuir wave electric fields at the remote source are estimated to be ≳ 3–30 μV/m.
Radiocarbon age of waters in the deep Atlantic revisited
Authors: Broecker Wallace S. , Virgilio Alex , Peng Tsung‐Hung
Published: February 2008

We use a simple box model to evaluate the impact of temporal changes of the atmosphere's 14C/C on ventilation fluxes for the deep Atlantic calculated from radiocarbon measurements. The conclusion is that despite the fact that over the 300 year period from 1650 to 1950 the atmosphere's radiocarbon content declined at the same rate as radiocarbon decays, this temporal change has a relatively small impact (10–15%) on radiocarbon‐based estimates of the ventilation rate of the deep Atlantic. The reason is that the radiocarbon content of the source waters for deep Atlantic are reasonably well buffered against changes in atmospheric 14C/C.
Spectral characteristics of plasma sheet ion and electron populations during disturbed geomagnetic conditions
Authors: Christon S. P. , Williams D. J. , Mitchell D. G. , Huang C. Y. , Frank L. A.
Published: February 2008

We have determined the spectral characteristics of central plasma sheet ions and electrons observed during 71 hours when geomagnetic activity was at moderate to high levels (AE ≥ 100 nT). Particle data from the low‐energy proton and electron differential energy analyzer and the medium energy particle instrument on ISEE 1 are combined to obtain differential energy spectra (measured in units of particles/cm² s sr keV) in the kinetic energy range ∼30 eV/e to ∼1 MeV at geocentric radial distances >12 Re. Nearly isotropic central plasma sheet total ion and electron populations were chosen for analysis and were measured to be continuous particle distributions from our lowest to highest energies. During these high AE periods the >24 keV particle fluxes and the temperature of the entire particle distribution kT are significantly higher than during low AE periods (AE < 100 nT). The temperatures kTi and kTe are highly correlated during both quiet and disturbed periods. The active period spectral shape appears softer for ions and somewhat harder for electrons than during quiet periods. We find that the observed active period spectrum typically is complex and cannot be represented in general by a single functional form, as during quiet periods when it can be represented by the kappa distribution function. Although a power‐law shape is observed at higher energies, ion and electron spectral shapes deviate from a strictly kappalike form in different ways. In a limited energy range near the knee of the ion spectra (the knee is that portion of the spectrum at energies E ≳ Eo where the flux starts to decrease swiftly with increasing energy), the spectral shape can often be fit with a Maxwellian form, thus rolling over faster than the typical quiet time spectrum. At higher energies this shape merges into a harder nonthermal power‐law tail. Electron spectra also display this spectral characteristic, although at a lower occurrence frequency than for ions. The electron spectra are predominantly kappalike at energies near and above the knee. At energies below the knee, both ions and electrons often have an excess of flux with respect to the functional form that best fits the shape for energies at or above the knee, be it a kappa distribution or a Maxwellian distribution; the electron flux excess is significantly greater than the ion flux excess. We conclude that both ions and electrons participate in at least two separate acceleration mechanisms as geomagnetic activity evolves from low AE to high AE values. We suggest that both spectrum‐preserving and spectrum‐altering heating processes (possibly involving nonlocal betatron acceleration and crosstail current sheet acceleration, respectively) participate in overall particle energization during geomagnetic active periods. Observations are compared to model predictions.
The influence of IMF BY on the high‐latitude thermospheric circulation during northward IMF
Authors: McCormac F. G. , Killeen T. L. , Thayer J. P.
Published: February 2008

Thermospheric neutral wind data, obtained by the Fabry‐Perot Interferometer (FPI) and Wind and Temperature Spectrometer (WATS) on the Dynamics Explorer 2 satellite during periods of northward interplanetary magnetic field (IMF Bz positive), show a dependence of the circulation on the magnitude and sign of the east–west component (By) of the IMF. Averaged thermospheric neutral wind vector fields, for the northern hemisphere, and data from several sets of satellite orbits, that illustrate the variation in the neutral wind structure as a function of time and IMF orientation, are presented and discussed. The results show that near December solstice, at solar maximum: (1) sunward neutral winds develop inside the geomagnetic polar cap during periods of persistent positive Bz and relatively low By; (2) typical time delays in the establishment of sunward winds following a northward turning of the IMF are approximately 4 hours; (3) sunward winds are not observed when the magnitude of the Bz component of the IMF is less than +4 nT; (4) the maximum‐velocity antisunward winds, in the central geomagnetic polar cap region, are on the duskside (dawnside) in the northern hemisphere during periods of northward IMF and By negative (positive). A similar asymmetry exists in the sunward flow in the center of the polar cap; (5) if the absolute magnitude of the By component of the IMF exceeds that of Bz (i.e., if the By/Bz ratio is greater than 1.0) then sunward winds inside the geomagnetic polar cap are rarely observed; instead, one sees a pattern of neutral winds similar to that expected for the given sign of By under southward IMF conditions; (6) the summer hemisphere has neutral wind signatures that are similar to those seen in the winter hemisphere for Bz northward, i.e., sunward winds occur in the polar cap for persistently northward Bz, provided the magnitude of By does not exceed that of Bz.
High‐latitude lower thermospheric neutral winds at EISCAT and Sondrestrom during LTCS 1
Authors: Johnson R. M. , Virdi T. S.
Published: February 2008

The incoherent scatter radar located at Søndre Strømfjord, Greenland (67°N, 51°W, 74.5°Λ) and the EISCAT incoherent scatter facility located in northern Scandinavia (69.5°N, 19°E, 66.3°Λ) both obtained E and F region measurements during the first campaign of the Lower Thermosphere Coupling Study (LTCS 1, September 21–25, 1987). Neutral winds deduced from these measurements have been analyzed for their mean flow and tidal components. A number of the altitude profiles for the mean winds and the diurnal and semidiurnal wave components at the two radar locations show similar variations with height, indicating that latitudinal rather than longitudinal effects are dominant in determining the observed wind field. Diurnal tidal amplitudes and phases are reasonably well represented by theoretical model results (Forbes, 1982). The semidiurnal amplitudes and phases, although somewhat consistent between the two radars, are not well represented in equinox tidal model results (Forbes and Vial, this issue). Results from both radars indicate a vertical wavelength for the zonal semidiurnal oscillation of approximately 60 km. During a period of impulsive magnetospheric forcing (September 22–23), winds deduced from measurements at both radars show enhanced eastward flows near midnight accompanied by equatorward winds at Sondrestrom. Comparison with the results of a National Center for Atmospheric Research thermosphere‐ionosphere general circulation model (TIGCM) simulation of the LTCS 1 interval shows generally better agreement with the observations at EISCAT than at Sondrestrom. During the period of activity on September 22–23 the TIGCM is reasonably successful at simulating the eastward surge near midnight in the EISCAT (but not in the Sondrestrom) observations and the equatorward flow after midnight in the Sondrestrom results. The observed winds in magnetic latitude and magnetic local time coordinates indicate the presence of anticyclonic divergent flow near dusk and cyclonic converging flow near dawn.
Electric field observations of equatorial bubbles
Authors: Aggson T. L. , Maynard N. C. , Hanson W. B. , Saba Jack L.
Published: February 2008

We present here results from the double floating probe experiment carried on the San Marco D satellite, with emphasis on the observation of large incremental changes in the convective electric field vector at the boundary of equatorial plasma bubbles. This study concentrates on isolated bubble structures in the upper ionospheric F region and divides these observed bubble encounters into two types, type I (live bubbles) and type II (dead bubbles). Type I bubbles show varying degrees of plasma density depletion and upward velocities ranging from 100 to 1000 m/s. Type II bubbles show plasma density depletion but no appreciable upward convection. Both types of events are often surrounded by a halo of plasma turbulence extending considerably outside the region's plasma depletion. Most type I events show some evidence for local continuity in the eastward (y) electric current, where the y component of the observed electric field (Ey) shows hyperbolic correlation with the plasma density (n), as dictated by horizontal current continuity. This model stresses the importance of including magnetic field aligned currents in deriving the electric potential equation from the divergence equation ▽ · j = 0. All of the type I (live) events examined exhibit a striking and systematic lack of conservation of the vertical component (x) of the electric field vector (Ex) on crossing these structures. This lack of conservation of Ex is of the order of 1.5 mV/m from west to east, directly implying that type I bubbles are not steady state plasma structures. A straightforward interpretation of this jump phenomenon in Ex leads to the conclusion that the walls of most of the type I bubbles are collapsing inward at the rate of some 50 m/s. Since the average east‐west dimension of the bubble structures we have examined here is of the order of 40 km, we conclude that the average lifetime of the strong upward convection phase is about 15 min. This suggests that after 15 min or so these type I events may be pinched off from the low densities of the bottomside F region and the bubbles perhaps become type II events which continue to drift eastward with the general background zonal plasma flow during the equatorial night. It is argued that the collapse motions may be driven by an asymmetry between the upwind (west) and downwind (east) E region drag on the F region eastward dynamo motions. Such an asymmetry appears to be of the proper magnitude and direction to produce the observed (∼1.5 mV/m) jump in the tangential (vertical) component of E on crossing these events.
Explosive events and magnetic reconnection in the solar atmosphere
Authors: Dere K. P. , Bartoe J.‐D. F. , Brueckner G. E. , Ewing J. , Lund P.
Published: February 2008

Explosive events are highly energetic, small‐scale phenomena which are frequently detected throughout the quiet and active Sun. They are seen in profiles of spectral lines formed at transition zone temperatures as exceptionally Doppler‐shifted features, typically at 100 km s−1 to the red and/or blue of the rest wavelength. Sufficient observational evidence has now been developed to demonstrate that some explosive events are associated with the emergence of new magnetic flux. In these cases it is likely that the acceleration of plasma is caused by the magnetic reconnection resulting from flux emergence. We take as a working hypothesis the proposal that all explosive events are the result of magnetic reconnection. Since explosive events tend to occur on the edges of high photospheric magnetic field regions, we identify them with reconnection that occurs during the cancellation of photospheric magnetic flux (Martin, 1984; Livi et al., 1985). The combined observational characteristics of photospheric flux cancellation and transition zone explosive events provide powerful diagnostic information concerning the nature of magnetic reconnection. Reconnection in the quiet solar atmosphere apparently proceeds in bursts at sites much smaller than the boundary between opposite polarity flux elements that are observed to cancel in magnetograph sequences. Equating the velocity of the expelled transition zone plasma with the Alfvén speed yields magnetic field strengths of 20 G at the site of reconnection. The speed at which the reconnection proceeds is commensurate with the rapid rates predicted by Petschek (1964).
Lifetime of ring current particles due to coulomb collisions in the plasmasphere
Authors: Fok M.‐C. , Kozyra J. U. , Nagy A. F. , Cravens T. E.
Published: February 2008

Ring current ions and electrons in the trapped belt are scattered and slowed down due to Coulomb interactions with the thermal plasma in the plasmasphere and are eventually removed from trapped orbits. An expression for bounce‐averaged Coulomb lifetimes is derived using methods developed by Wentworth et al. (1959) but with the improvements of considering a more realistic representation of the thermal plasma distribution, as a Maxwellian rather than a delta function, and considering heavy ions in the ring current and thermal plasmas. Bounce‐averaged Coulomb lifetimes for the major ring current ions are presented and are compared to Coulomb lifetimes in the literature. Coulomb lifetimes for ring current ions with energies less than ∼10 keV are longer than those predicted using previously derived expressions; however, they are comparable to, or shorter than, charge exchange lifetimes at these energies. For realistic thermal plasma densities in the outer plasmasphere, Coulomb lifetimes for ring current heavy ions can be comparable to charge exchange lifetimes at energies near the peak of the ring current differential number density. These results suggest that Coulomb decay is an important ring current loss process for tens of keV ions and might explain the discrepancy noted by Kistler et al. (1989) between modeled ring current distributions and the ring current fluxes measured by AMPTE/CCE during magnetically active conditions.
Field‐aligned currents observed in the inner magnetosphere and their magnetic signature on the ground
Authors: Wu J. , Stening R. J.
Published: February 2008

ISEE 2 magnetometer data and ISEE 1/2 particle data from the first half of 1978 were examined to search for signatures of field‐aligned currents in the Earth's inner magnetosphere (2.6–9.5 RE, L = 4.8–13.1). Eighteen field‐aligned current sheet “events” were found. Most of them occur during magnetically disturbed periods (AE = 226–724 nT). The surface current densities range from 12 to 113 mA/m and are compatible with magnitudes measured at low altitudes by TRIAD. In nearly every “event” gradients in the proton flux (32–50 keV and 80–126 keV are found in the vicinity of the field‐aligned currents indicating that the currents are located on or adjacent to the outer boundary of the plasma sheet. Using the Tsyganenko‐Usmanov magnetospheric field model to trace the field line from where the field‐aligned current signature was observed down to the ground, we found that the pattern is consistent with Iijima and Potemra's (1978) observation of large‐scale Birkeland currents in the polar region. Geomagnetic field data on the nightside, measured by about 10 observatories for each “event”, were used to study the magnetic field behavior on the ground. Even though we found both region 1 and region 2 currents from the ISEE data in the inner magnetosphere during magnetically disturbed periods, the ground magnetic signatures favor only the region 1 currents and also indicate the transient nature of the current flows.
Biotic effects of sea level change: The Pleistocene test
Authors: Valentine James W. , Jablonski David
Published: February 2008

Species diversity change, and therefore compositional changes in a biota, may be associated with changes at any of three ecological levels, involving the number of provinces within the biosphere, of communities within provinces, and of species represented within communities. Pleistocene sea level changes did not much affect the marine biosphere at any ecological level. An analysis of an extensive data set of Californian Pleistocene and Recent mollusks indicates a continuity of community and species composition during highstands of the last million years. Extensive latitudinal shifts in species' geographic ranges, associated with climatic change and not with sea level itself, created the most significant biotic changes. Extinctions were minimal, well below predicted species‐area effects. Evidently, only “perched” faunas are particularly vulnerable to sea level change. Although sea level falls are commonly associated with a faunal hiatus, changes associated therewith can be referred to sea level change itself only in limited situations, and other paleobiologic explanations should be sought in most cases.
Geochemistry of basalts from the southeast Indian Ridge, 115°E–138°E
Authors: Klein Emily M. , Langmuir Charles H. , Staudigel Hubert
Published: February 2008

The ocean basin south of Australia contains the Australian‐Antarctic Discordance, an anomalously deep portion of the Southeast Indian Ridge that marks a boundary between isotopic provinces characteristic of the Indian and Pacific oceans. Samples recovered from the ridge within the discordance display unusual chemical compositions compared to normal mid‐ocean ridge basalt (N‐MORB) of the same MgO contents, including low iron, high silica, and high sodium abundances and elevated abundances of highly incompatible trace elements. In contrast, samples from the ridge east of the discordance, where the ridge is of average axial depth, display major and trace element systematics more typical of N‐MORB. Major and moderately incompatible trace elements show no evidence of a discontinuity in source composition corresponding to the location of the known isotopic discontinuity within the discordance. Ratios of highly incompatible trace elements, however, reveal a gradational change in the range of values across the location of the isotopic discontinuity. Modelling of along‐strike variations in major element chemistry suggest they may result from systematic variations in the extent and pressure of melting. The lowest solidus pressures and least extents of melting occur in the mantle beneath the discordance, supporting geophysical inferences based on bathymetric, gravity, and seismic evidence that the discordance overlies a region of cooler mantle temperatures.
The simulation of the sedimentary fill of basins
Authors: Kendall C. G. St. C. , Strobel J. , Cannon R. , Bezdek J. , Biswas G.
Published: February 2008

An interactive computer simulation which erects models of sedimentary geometries by filling in a two‐dimensional basin from both sides with a combination of clastic sediment and/or in situ and transported carbonate sediments is described. The simulation program is implemented in “C” using graphical plotting functions. Data entry, including the initial basin configuration, the local tectonic behavior, the sea level curves, the amount and source direction of clastic sediment, and the growth rates of carbonates as a function of water depth is performed interactively. Geometries of clastic and carbonate sediments evolve through time and respond to tectonic movement, eustasy, and sedimentation. Clastic modeling includes sedimentary bypass and erosion and sedimentation in alluvial and coastal plains, marine shelf, basin slope, and basin floor settings. Carbonate modeling includes progradation, the development of hard grounds, downslope aprons, keep up, catch up, back step, and drowned reef settings as well as lagoonal and epeiric settings. Also included in the model are extensional vertical faulting of the basin, sediment compaction, and isostatic response to sediment loading. Sediment geometries are plotted on a graphics terminal as they are computed, so the user can immediately view the results. Based on these observations, parameters can be changed and the program rerun until the user is satisfied with the resultant geometry. This paper includes output showing the simulation's sensitivity to eustatic sea level variations, and variations in sedimentation and subsidence rates. Also shown are outputs demonstrating the modeling of some examples from the geologic section in the Permian Basin of west Texas and the Upper Permian of the Sichuan Basin.
High‐temperature creep of olivine single crystals 1. Mechanical results for buffered samples
Authors: Bai Q. , Mackwell S. J. , Kohlstedt D. L.
Published: February 2008

To investigate the rheological behavior of the Earth's upper mantle, over 100 high‐temperature deformation experiments have been performed on single crystals of San Carlos olivine in controlled chemical environments at a total pressure of 0.1 MPa. Constitutive equations have been determined which describe the dependence of creep rate on applied stress, temperature and oxygen fugacity in terms of power law relations. In addition, the effects of orthopyroxene activity and loading orientation on the creep behavior have been investigated. For samples of each of three compression directions, [101]c, [011]c and [110]c, buffered by orthopyroxene or magnesiowustite, either two or three power law equations are required to describe the dependence of strain rate at fixed stress on temperature and oxygen fugacity over the full range of experimental conditions. It is proposed that in each power law regime a different creep mechanism controls the creep rate. For all of the experimental conditions, the activation energy for creep is independent of the stress level and the stress exponent is constant at 3.5±0.1. Activation energies for the various creep mechanisms varied from 230 to 1000 kJ/mol; and oxygen fugacity exponents lie in the range −0.03 to 0.4. From the constitutive equations determined based on the power law equations for all of the creep mechanisms,
deformation maps were constructed at a stress of 1 MPa for olivine.