bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Ethylene Oxide and Propylene Oxide Groups of Pluronics in Binding of Fatty Acid to Pluronics in Microemulsions
Authors: James‐Smith Monica A. , Shekhawat Dushyant , Cheung Sally , Moudgil Brij M. , Shah Dinesh O.
Published: July 2008

We investigated the drug and fatty acid binding capacity of Pluronic‐based microemulsions through simple turbidity experiments. Pluronic‐based oil‐in‐water microemulsions of various compositions were synthesized and titrated to turbidity with concentrated amitriptyline, an antidepressant drug. The BASF Pluronic grid was used to select two series of Pluronic surfactants: (1) those having the same number of ethylene oxide (EO) groups, with an increasing number of propylene oxide (PO) groups and (2) those having the same number of propylene oxide groups with an increasing number of ethylene oxide groups. We observed that the binding of sodium caprylate fatty acid and amitriptyline drug increases with increasing hydrophobicity (i.e., increasing number of PO groups). This is attributed to the greater number of binding sites for the sodium caprylate, which results in more charge on the microemulsion, subsequently leading to increased drug binding. We also determined that when the number of PO groups was held fixed and the number of EO groups was increased, there is no direct correlation to the binding behavior of fatty acid and drug. This is due to the fact that the hydrophilic groups (EO) do not play a direct role in the binding of fatty acid molecules. In fact, when there are a significantly large number of EO groups present, they can act to inhibit binding of fatty acid and hence, drug, to the microemulsion.
Dietary n‐3 HUFA Affects Mitochondrial Fatty Acid β‐Oxidation Capacity and Susceptibility to Oxidative Stress in Atlantic Salmon
Authors: Kjær M. A. , Todorčević M. , Torstensen B. E. , Vegusdal A. , Ruyter B.
Published: July 2008

Atlantic salmon (Salmo salar) (90 g) were fed four different diets for 21 weeks (final weight 344 g). The levels of n‐3 highly unsaturated fatty acids (HUFA) ranged from 11% of the total fatty acids (FA) in the low n‐3 diet to 21% in the intermediate n‐3 diet, to 55 and 58% in the high n‐3 diets. The high n‐3 diets were enriched with either docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA). Increasing dietary levels of n‐3 HUFA led to increasing percentages (from 31 to 52%) of these FA in liver lipids. The group fed the highest level of DHA had higher expressions of peroxisome proliferator‐activated receptor (PPAR) β and the FA β‐oxidation genes acyl‐CoA oxidase (ACO) and carnitine palmitoyltransferase (CPT)‐II, compared to the low n‐3 groups. The high n‐3 groups had reduced activity of mitochondrial cytochrome c oxidase and β‐oxidation capacity, together with increased activities of superoxide dismutase (SOD) and caspase‐3 activities. In the group fed the highest level of n‐3 HUFA, decreased percentages of major phospholipids (PL) in the mitochondrial and microsomal membranes of the liver were also apparent. The percentage of mitochondrial cardiolipin (Ptd2Gro) was 3.1 in the highest n‐3 group compared to 6.6 in the intermediate group. These data clearly show an increased incidence of oxidative stress in the liver of fish fed the high n‐3 diets.
Comparing homotopy categories
Authors: Blanc David
Published: July 2008

Given a suitable functorT:→between model categories, we define a long exact sequence relating the homotopy groups of anyXεwith those ofTX, and use this to describe an obstruction theory for lifting an objectGεto. Examples include finding spaces with given homology or homotopy groups.
Projectivity of Hopf algebras over subalgebras with semilocal central localizations
Authors: Skryabin Serge
Published: July 2008

The purpose of this paper is to extend the class of pairs A, H where H is a Hopf algebra over a field and A a right coideal subalgebra for which H is proved to be either projective or flat as an A-module. The projectivity is obtained under the assumption that H is residually finite dimensional, A has semilocal localizations with respect to a central subring, and there exists a Hopf subalgebra B of H such that the antipode of B is bijective and B is a finitely generated A-module. The flatness of H over A is shown to hold when H is a directed union of residually finite dimensional Hopf subalgebras, and there exists a Hopf subalgebra of H whose center contains A. More general projectivity and flatness results are established for (co)equivariant modules over an H-(co)module algebra under similar assumptions.
Design of series damper actuator
Authors: Zhou Wei , Chew Chee-Meng , Hong Geok-Soon
Published: July 2008

In our previous work, a novel force control actuator, called series damper actuator (SDA), has been proposed. This paper proposes a general design procedure for the SDA system. From design requirements, several key parameters of the SDA plant can be determined. Based on these parameters, the selection or design of the series damper and the motor can be carried out. A case study is included to illustrate the effectiveness of the procedure. As there could be more than one feasible solutions from the procedure, the mechatronic design quotient (MDQ) method can be adopted to select the best solution from a feasible solution space.
Improving the stability level for on-line planning of mobile manipulators
Authors: Qiu Changwu , Cao Qixin , Yu Leibin , Miao Shouhong
Published: July 2008

This paper presents a quadratic programming (QP) form algorithm to realize on-line planning of mobile manipulators with consideration for improving the stability level. With Lie group and screw tools, the general tree topology structure mobile robot dynamics and dynamic stability attributes were analysed. The stable support condition for a mobile robot is constructed not only in a polygonal support region, but also in a polyhedral support region. For a planar supporting region, the tip-over avoiding requirement is formulated as the tip-over prevent constraints with the reciprocal products of the resultant support wrench and the imaginary tip-over twists, which are constructed with the boundaries of the convex support polygon. At velocity level, the optimized resolution algorithm with standard QP form is designed to resolve the inverse redundant kinematics of the Omni-directional Mobile ManipulatorS (OMMS) with stability considerations. Numerical simulation results show that the presented methods successfully improve the stability level of the robot within an on-line planning process.
DETECTION OF FUNCTIONAL FORM MISSPECIFICATION IN COINTEGRATING RELATIONS
Authors: Kasparis Ioannis
Published: July 2008

A simple specification test based on fully modified residuals and the cumulative sum (CUSUM) test for cointegration of Xiao and Phillips (2002,Journal of Econometrics, 108, 43–61) are considered as means of testing for functional form in long-run cointegrating relations. It is shown that both tests are consistent under functional form misspecification and lack of cointegration. A simulation experiment is carried out to assess the properties of the tests in finite samples. The Dickey–Fuller test is also considered. The simulation results reveal that the first two tests perform reasonably well. However, the Dickey–Fuller test performs poorly under functional form misspecification.
DATA DEPENDENT RULES FOR SELECTION OF THE NUMBER OF LEADS AND LAGS IN THE DYNAMIC OLS COINTEGRATING REGRESSION
Authors: Kejriwal Mohitosh , Perron Pierre
Published: July 2008

Saikkonen (1991, Econometric Theory 7, 1–21) developed an asymptotic optimality theory for the estimation of cointegrated regressions. He proposed the dynamic ordinary least squares (OLS) estimator obtained by augmenting the static cointegrating regression with leads and lags of the first differences of the I(1) regressors. However, the assumptions imposed preclude the use of information criteria such as the Akaike information criterion (AIC) and Bayesian information criterion (BIC) to select the number of leads and lags. We show that his results remain valid under weaker conditions that permit the use of such data dependent rules. Simulations show that, relative to sequential general to specific testing procedures, the use of such information criteria can indeed produce estimates with smaller mean squared errors and confidence intervals with better coverage rates.
UNIFORM CONVERGENCE OF SERIES ESTIMATORS OVER FUNCTION SPACES
Authors: Song Kyungchul
Published: July 2008

This paper considers a series estimator ofE[α(Y)|λ(X) = λ̄], (α,λ) ∈ 𝛢 × Λ, indexed by function spaces, and establishes the estimator's uniform convergence rate over λ̄ ∈R, α ∈ 𝛢, and λ ∈ Λ, when 𝛢 and Λ have a finite integral bracketing entropy. The rate of convergence depends on the bracketing entropies of 𝛢 and Λ in general. In particular, we demonstrate that when each λ ∈ Λ is locally uniformly ℒ2-continuous in a parameter from a space of polynomial discrimination and the basis function vectorpKin the series estimator keeps the smallest eigenvalue ofE[pK(λ(X))pK(λ(X))‼] above zero uniformly over λ ∈ Λ, we can obtain the same convergence rate as that established by de Jong (2002,Journal of Econometrics111, 1–9).
GENERAL TRIMMED ESTIMATION: ROBUST APPROACH TO NONLINEAR AND LIMITED DEPENDENT VARIABLE MODELS
Authors: Čížek Pavel
Published: July 2008

High-breakdown-point regression estimators protect against large errors and data contamination. We generalize the concept of trimming used by many of these robust estimators, such as the least trimmed squares and maximum trimmed likelihood, and propose a general trimmed estimator, which renders robust estimators applicable far beyond the standard (non)linear regression models. We derive here the consistency and asymptotic distribution of the proposed general trimmed estimator under mild β-mixing conditions and demonstrate its applicability in nonlinear regression and limited dependent variable models.
M-ESTIMATION IN GARCH MODELS
Authors: Mukherjee Kanchan
Published: July 2008

This paper derives asymptotic normality of a class ofM-estimators in the generalized autoregressive conditional heteroskedastic (GARCH) model. The class of estimators includes least absolute deviation and Huber's estimator in addition to the well-known quasi maximum likelihood estimator. For some estimators, the asymptotic normality results are obtained only under the existence of fractional unconditional moment assumption on the error distribution and some mild smoothness and moment assumptions on the score function.
Analysis of the FoodNet case-control study of sporadicSalmonellaserotype Enteritidis infections using persons infected with otherSalmonellaserotypes as the comparison group
Authors: VOETSCH A. C. , POOLE C. , HEDBERG C. W. , HOEKSTRA R. M. , RYDER R. W. , WEBER D. J. , ANGULO F. J.
Published: July 2008

Use of well persons as the comparison group for laboratory-confirmed cases of sporadic salmonellosis may introduce ascertainment bias into case-control studies. Data from the 1996–1997 FoodNet case-control study of laboratory-confirmedSalmonellaserogroups B and D infection were used to estimate the effect of specific behaviours and foods on infection withSalmonellaserotype Enteritidis (SE). Persons with laboratory-confirmedSalmonellaof other serotypes acted as the comparison group. The analysis included 173 SE cases and 268 non-SE controls. SE was associated with international travel, consumption of chicken prepared outside the home, and consumption of undercooked eggs prepared outside the home in the 5 days prior to diarrhoea onset. SE phage type 4 was associated with international travel and consumption of undercooked eggs prepared outside the home. The use of ill controls can be a useful tool in identifying risk factors for sporadic cases ofSalmonella.
Adaptation and Validation of the German Sensitivity to Befallen Injustice Scales into French
Authors: Faccenda Lionel , Pantaléon Nathalie , Bois Julien E. , Schmitt Manfred
Published: July 2008

Justice sensitivity (JS) was introduced as a personality construct that contributes to the explanation of individual differences in justice judgment and behavior. Schmitt, Gollwitzer, Maes, and Arbach (2005 ) developed scales for measuring three types of justice sensitivity: victim sensitivity, observer sensitivity, and beneficiary sensitivity. The aim of the present study was to adapt these scales into French and to validate them, following the steps of the cross-cultural validation procedure detailed by Vallerand (1989 ). Four studies involving a total of 1,200 participants were conducted in order to establish a preliminary French version of the scales, to analyse their factorial validity via exploratory and confirmatory factor analyses and, last, to analyze the temporal stability of the final French version of the JS scales. Factor analysis revealed a three-dimensional solution similar to that of the original German version. The French scales have satisfactory internal consistency and stability. The entire pattern of the results suggests that the use of the French scales is pertinent to studies on injustice.
Brief Form of the Social Phobia and Anxiety Inventory (SPAI-B) for Adolescents
Authors: Garcia-Lopez Luis Joaquin , Hidalgo Maria D. , Beidel Deborah C. , Olivares Jose , Turner† Samuel
Published: July 2008

Although social phobia is one of the most common mental disorders in adolescents, there are few reliable and valid assessment instruments for this age group. This study examined the factor structure and psychometric properties of a brief version of the Social Phobia and Anxiety Inventory (SPAI; Turner, Beidel, Dancu, & Stanley, 1989 ) in a sample of adolescents. Although the original 45-item SPAI has excellent psychometric properties, its utility is limited by its length. We developed and piloted a brief, 16-item version of the SPAI that has good psychometric properties, assesses cognitive, behavioral, and somatic symptoms, consistent with the original scale, which may be particularly useful as a screening measure. Limitations and suggestions for future research are discussed.
Validating Four Standard Scales in Spiritually Practicing and Nonpracticing Samples Using Propensity Score Matching
Authors: Kohls Niko , Walach Harald
Published: July 2008

Validation studies of standard scales in the particular sample that one is studying are essential for accurate conclusions. We investigated the differences in answering patterns of the Brief-Symptom-Inventory (BSI), Transpersonal Trust Scale (TPV), Sense of Coherence Questionnaire (SOC), and a Social Support Scale (F-SoZu) for a matched sample of spiritually practicing (SP) and nonpracticing (NSP) individuals at two measurement points (t1, t2). Applying a sample matching procedure based on propensity scores, we selected two sociodemographically balanced subsamples of N = 120 out of a total sample of N = 431. Employing repeated measures ANOVAs, we found an intersample difference in means only for TPV and an intrasample difference for F-SoZu. Additionally, a group × time interaction effect was found for TPV. While Cronbach’s α was acceptable and comparable for both samples, a significantly lower test-rest-reliability for the BSI was found in the SP sample (rSP = .62; rNSP = .78). Thus, when researching the effects of spiritual practice, one should not only look at differences in means but also consider time stability. We recommend propensity score matching as an alternative for randomization in variables that defy experimental manipulation such as spirituality.
Interviewers’ Sensitivity to Impression Management Tactics in Structured Interviews
Authors: Lievens Filip , Peeters Helga
Published: July 2008

This study examines interviewers’ sensitivity to impression management in structured interviews by determining the relative importance that interviewers attach to (verbal and nonverbal) impression management as compared to the relative importance that they attach to predetermined competencies. Two samples of interviewers (55 Master I/O psychology students and 18 professional interviewers) watched and evaluated videotaped interviewees who were instructed to put their best foot forward. Results of relative weight analyses showed that the importance of verbal and nonverbal impression management tactics was relatively small as compared to the importance attached to job-related competencies. The type of interview format had some effect on interviewers’ sensitivity to impression management tactics. In particular, in behavior description interviews the interviewers in both samples attached most relative weight to self-focused verbal tactics. Interviewer experience was not related to interviewers’ sensitivity to impression management tactics.
Dimensionality and Norms of the Rosenberg Self-esteem Scale in a German General Population Sample
Authors: Roth Marcus , Decker Oliver , Herzberg Philipp Yorck , Brähler Elmar
Published: July 2008

This study analyzed the dimensionality of the German version of Rosenberg’s Self-Esteem scale (RSES) in a nationally representative population sample of 4,988 subjects (46.4% males; aged 14–92 years). Using confirmatory factor analysis, one- and two-dimensional models were tested. Results suggest that the RSES is a two-dimensional scale comprising the highly correlated components positive and negative self-evaluation, which constitute a unitary construct of global self-esteem at the second-order level. In order to obtain a more conclusive solution, an item response theory (IRT) analysis (partial credit model) was conducted. Results lend support to a one-dimensional view of the RSES. Furthermore, psychometric properties and norm values based on the representative sample are reported. Analyses revealed extremely high response probabilities for all items, as a consequence of which self-esteem cannot be differentiated at the upper end of the range.
Construct Validation and Psychometric Evaluation of the Self-Efficacy Scale for Driver Competence
Authors: Sundström Anna
Published: July 2008

The aim of the present study was to examine the construct validity of the Self-Efficacy Scale for Driver Competence (SSDC). The SSDC was based on a theoretical model for perceived driver competence, based on the self-efficacy construct and five aspects of driver competence. Two samples of driving license examinees (n = 805, n = 721) completed two parallel versions of the SSDC. Participants’ mean age was 21.5 years and of them 44% were women. Both versions of the SSDC had sound psychometric properties. The results provided support for substantial and structural aspects of construct validity. Some evidence of external validity of the test scores was obtained, although the relationship between perceived and actual driver competence was weaker than expected. The consequences of the use and interpretation of SSDC are discussed.
Modeling of scintillation effects on high‐latitude transionospheric paths using ionospheric model (UAF EPPIM) for background electron density specifications
Authors: Maurits Sergei A. , Gherm Vadim E. , Zernov Nikolay N. , Strangeways Hal J.
Published: July 2008

This paper addresses the effects of scintillation on high‐latitude paths of propagation. To specify the high‐latitude ionosphere environment as a time‐dependent three‐dimensional distribution of the electron density, the first‐principles ionospheric model UAF EPPIM (University of Alaska Fairbanks Eulerian Parallel Polar Ionosphere Model) is utilized. For the specification of time‐varying small‐scale irregularities, superimposed onto the background EPPIM, the full three‐dimensional inverse power law spectrum is chosen. It is augmented with the introduction of the irregularities' aspect ratio for two mutually perpendicular directions: transverse (to the geomagnetic field) direction and for the longitudinal direction to the transverse one. This full description of the propagation environment, comprised of the “background” and “irregularities” components, is further merged with the propagation scintillation model to set up the computational suite, capable of modeling the scintillation effects. The parameters of the spectrum of the electron density fluctuations, as well as the models of meso‐scale local polar structures (e.g., patches) are chosen empirically. The integrated simulator enables realistic predictions of the scintillation effects for high‐latitude transionospheric propagation for a number of different propagation scenarios for GPS L‐band and other UHF transionospheric signals. The specific scintillation effects, caused by ionospheric patches, are simulated.
Superposed epoch analysis of the dayside ionospheric response to four intense geomagnetic storms
Authors: Mannucci A. J. , Tsurutani B. T. , Abdu M. A. , Gonzalez W. D. , Komjathy A. , Echer E. , Iijima B. A. , Crowley G. , Anderson D.
Published: July 2008

Prompt daytime ionospheric responses are presented for the following four intense geomagnetic storms: 29 October 2003, 30 October 2003, 20 November 2003, and 7 November 2004. We perform a superposed epoch analysis of the storms by defining the start time of the epoch when the Kan‐Lee interplanetary electric field (proportional to the reconnection electric field) first reaches 10 mV/m during a period of continuously southward Bz. Measurements from the GPS receiver onboard the CHAMP satellite at 400 km altitude indicate significant low‐ to middle‐latitude daytime total electron content (TEC) increases above the satellite within 1–2 h of the defined start time for three of the storms (∼1400 local solar time). The 20 November 2003 data follow a different pattern: the largest TEC increases appear several hours (∼5–7) following the interplanetary magnetic field Bz event onset. TEC data obtained from ground‐based GPS receivers for the November 2003 storm tend to confirm a “late” TEC increase for this storm at ∼1400 LT. Estimates of vertical plasma uplift near the equator at Jicamarca longitudes (∼281 E) using the dual‐magnetometer technique suggest that variability of the timing of the TEC response is associated with variability in the prompt penetration of electric fields to low latitudes. It is also found that for the November 2003 magnetic storm the cross‐correlation function between the SYM‐H index and the interplanetary electric field reached maximum correlation with a lag time of 4 h. Such a large lag time has never been noted before. The long delays of both the ionosphere and magnetosphere responses need to be better understood.
Polar mesospheric clouds: Infrared measurements from the Midcourse Space Experiment
Authors: O'Neil Robert R. , Richards Edward , Humphrey Charles H. , Stair A. T.
Published: July 2008

Spatial Infrared Imaging Telescope (SPIRIT) III radiometer on the Midcourse Space Experiment (MSX) satellite measured highly structured infrared, IR, emission from polar mesospheric cloud (PMC) ice particles at northern latitudes above 51 degrees on 22 July 1996 in the 11.1 to 13.2 and 18.2 to 25.1 μm radiometer channels, bands C and E, respectively. Measurements of the PMC thermal emissions included the observation of an extended cloud at 84.8°N and 325.6°E at 0313:25 UT, a local solar time of approximately 0056. In this Earth limb observation, the radiance due to the PMC has been isolated from other sources‐atmospheric emission, nonrejected off axis radiation from the terrestrial surface and zodiacal radiance‐and inverted to determine the volume emission rates of the ice particles at a spatial resolution of 0.3 km in the altitude range from 83.4 to 86.4 km. The band C PMC volume emission rate profile has a maximum value at 84.0 ± 0.3 km and decreases to one half the peak value at 85.0 and 83.5 km. Temperatures in the range from 143 ± 7 to 130 ± 8 K and ice volume densities from 1.5 to 0.5 × 10−13 cm3 per cm3 were determined from the LWIR volume emission rates at altitudes from 83.4 to 86.4 km. The PMC ice densities are equivalent to an enriched gas phase water mixing ratio of 8 to 16 parts per million by volume, ppmv, and a vertical column mass density of 3.3 × 10−8 gms cm−2 in this observation.
Auroral arcs as current transformers
Authors: Haerendel Gerhard
Published: July 2008

We treat the effects of an electric field tangential to an auroral arc on the basis of an analytical model according to which auroral arcs are energized by the release of magnetic shear stresses and associated internal energy (Haerendel, 2007). If the tangential field exceeds a certain (low) threshold, the ionosphere acts as a current generator, or better transformer, and the magnetosphere as the load. The reason is that energy supplied by a longitudinal Type I current system, as defined by Boström in 1964, is transformed into energy of the latitudinal Type II current system attached to the arc and is mostly consumed by the auroral acceleration process. Closure of the transformer current in the upper magnetosphere and energy deposition in form of internal energy and shear stresses, although small, are crucial for the operation of this process. It can be visualized as a dragging of magnetic field and plasma along the arc in the direction of higher magnetospheric pressure enforced by the electric polarization field. This energy deposition from below is superimposed on the release of free energy supplied by the magnetospheric generator. Formulation of this scenario leads to a set of algebraic equations, whose solution provides quantitative answers on the interdependence of current closure, energy deposition, and enhanced auroral energy flux in relation to the imposed tangential electric field. Contrary to earlier expectations, the polarization field appears not as a consequence of current blockage, but as manifestation of its continuation by field‐aligned currents and their closure in the magnetosphere. Another consequence of the energy deposition from below is a small modification of the arc's proper motion in the ambient plasma frame. A procedure for evaluating applicable measurements in terms of the underlying physics is given and a concrete example added.
Three‐dimensional finite difference simulation of long‐period ground motions for the 2003 Tokachi‐oki, Japan, earthquake
Authors: Aoi Shin , Honda Ryou , Morikawa Nobuyuki , Sekiguchi Haruko , Suzuki Haruhiko , Hayakawa Yuzuru , Kunugi Takashi , Fujiwara Hiroyuki
Published: July 2008

To explore the generation and propagation mechanisms of long‐period ground motions, we used a 3‐D finite difference method to simulate wave propagation during the 2003 Mw 8.3 Tokachi‐oki, Japan, earthquake. A large‐scale computation with an inverted slip model and a geological‐ and geophysical‐based velocity structure model successfully reproduced the overall characteristics of substantial observed velocity seismograms for a period range of 3.3 to 25 s. Significant long‐period ground motions of extended duration were observed in the Yufutsu basin, where oil tanks were damaged at Tomakomai because of sloshing associated with the ground motions. Our simulation revealed that the combination of the large and shallow earthquake and the deep extent of the sedimentary basin generated long‐period ground motions with a duration of several hundred seconds. The Yufutsu basin contains an internal subbasin that deepens from east to west, in contrast with the geometry of the overall basin that deepens from west to east. The long‐period ground motions were amplified in both the eastern and western parts of the basin, with the durations being greatly extended in the western part. A series of computations with and without each of the velocity layers within the basin demonstrated that the basin response amplifies long‐period ground motions as expected and that the subbasin response is effective in amplifying and extending long‐period ground motions. Our quantitative 3‐D finite difference simulations clarify the generation of disastrous long‐period ground motions that occurred in the Yufutsu basin during the 2003 Tokachi‐oki earthquake.
Observations of regional seismicity and local harmonic tremor at Brothers volcano, south Kermadec arc, using an ocean bottom hydrophone array
Authors: Dziak R. P. , Haxel J. H. , Matsumoto H. , Lau T. K. , Merle S. G. , de Ronde C. E. J. , Embley R. W. , Mellinger D. K.
Published: July 2008

Four ocean bottom hydrophones (OBHs) were deployed for 7 months on the caldera floor of Brothers volcano, located within the southern Kermadec intraoceanic arc roughly 350 km northeast of New Zealand. The volcanic edifice is 13 × 8 km at the seafloor, with a 3 km wide caldera that has a floor depth of 1850 m and which is surrounded by 290‐ to 530‐m‐high walls encompassing a ∼350‐m‐high dacite cone. Three of the OBHs recorded low‐frequency (0.5–110 Hz) acoustic T waves from regional and local earthquakes, as well as harmonic tremor from within the Brother volcano. The fourth OBH was not recovered intact. The T wave‐derived locations for 964 regional earthquakes show that the majority of events cluster beneath the dacite cone in the southern quadrant of the caldera and the east flank of Brothers volcano. In addition, regional seismicity was observed along a NE‐SW trending fault structure to the southeast and northwest of the volcano in a small basin in the Kermadec back arc and along the Kermadec arc and fore arc. A total of 2470 discrete harmonic tremor events were recorded on all three OBHs with a fundamental frequency of 3 ± 0.5 Hz. The majority of tremor signals were detected on OBH‐2, implying that a greater number of hydrothermal fluid conduits/chambers exist within the southern caldera quadrant in comparison with the eastern or western quadrants of the caldera.
Vertical stability and the annual dynamics of nutrients and chlorophyll fluorescence in the coastal, southeast Beaufort Sea
Authors: Tremblay Jean‐Éric , Simpson Kyle , Martin Johannie , Miller Lisa , Gratton Yves , Barber David , Price Neil M.
Published: July 2008

The first quasi‐annual time series of nutrients and chlorophyll fluorescence in the southeast Beaufort Sea showed that mixing, whether driven by wind, local convection, or brine rejection, and the ensuing replenishment of nutrients at the surface were minimal during autumn and winter. Anomalously high inventories of nutrients were observed briefly in late December, coinciding with the passage of an eddy generated offshore. The concentrations of NO3− in the upper mixed layer were otherwise low and increased slowly from January to April. The coincident decline of NO2− suggested nitrification near the surface. The vernal drawdown of NO3− in 2004 began at the ice‐water interface during May, leaving as little as 0.9 μM of NO3− when the ice broke up. A subsurface chlorophyll maximum (SCM) developed promptly and deepened with the nitracline until early August. The diatom‐dominated SCM possibly mediated half of the seasonal NO3− consumption while generating the primary NO2− maximum. Dissolved inorganic carbon and soluble reactive phosphorus above the SCM continued to decline after NO3− was depleted, indicating that net community production (NCP) exceeded NO3− ‐based new production. These dynamics contrast with those of productive Arctic waters where nutrient replenishment in the upper euphotic zone is extensive and NCP is fueled primarily by allochthonous NO3−. The projected increase in the supply of heat and freshwater to the Arctic should bolster vertical stability, further reduce NO3− ‐based new production, and increase the relative contribution of the SCM. This trend might be reversed locally or regionally by the physical forcing events that episodically deliver nutrients to the upper euphotic zone.
Validation of OMI tropospheric NO2 column densities using direct‐Sun mode Brewer measurements at NASA Goddard Space Flight Center
Authors: Wenig M. O. , Cede A. M. , Bucsela E. J. , Celarier E. A. , Boersma K. F. , Veefkind J. P. , Brinksma E. J. , Gleason J. F. , Herman J. R.
Published: July 2008

This paper presents a comparison of NO2 data measured with the Ozone Monitoring Instrument (OMI) on board the EOS‐AURA satellite with ground‐based direct‐Sun Brewer measurement data. Since its deployment in July 2004, OMI has provided more than 2 years of daily high‐resolution (∼13 × 24 km2 at nadir) NO2 vertical column density maps. We describe the retrieval, which includes an estimation of the stratospheric and tropospheric fraction of total NO2 columns, the air mass factor (AMF) correction based on detected tropospheric NO2 enhancements, and the generation of the gridded data product. We present a validation study of the gridded NO2 data set using data from a Brewer MK3 double monochromator in direct‐Sun mode located at NASA Goddard Space Flight Center in Greenbelt, Maryland, USA. Monthly averages of coinciding measurements correlate well (r = 0.9) but OMI data are about 25% lower than the Brewer measurement data (slope 0.75, intercept −0.38 × 1015 molecules/cm2). We present a detailed uncertainty analysis for both ground and satellite data and discuss the possible reasons for the observed differences.
Constraining the composition and thermal state of Mars from inversion of geophysical data
Authors: Khan A. , Connolly J. A. D.
Published: July 2008

We invert the most recent determinations of Martian second degree tidal Love number, tidal dissipation factor, mean density and moment of inertia for mantle composition and thermal state using a stochastic sampling algorithm. We employ Gibbs energy minimization to compute the stable mineralogy of the Martian mantle in the model system CaO‐FeO‐MgO‐Al2O3‐SiO2. This procedure yields density and P and S‐wave velocities in the mantle as a function of depth and temperature and permits direct inversion for composition and thermal state. We find a Martian mantle composition resembling the model composition based on geochemical analyses of Martian meteorites. A prominent discontinuity in all physical properties occurs at ∼1100 km depth, marking the onset of the mantle transition zone and coincides with the olivine → wadsleyite + ringwoodite phase transition. A smaller discontinuity in the upper mantle related to the orthopyroxene → C2/c‐pyroxene + garnet is also apparent. A lower mantle discontinuity is not observed, as pressure and temperature conditions at the core mantle boundary (∼20 GPa, ∼1800°C) are insufficient to stabilize perovskite and magnesiowüstite. The most probable core radius is ∼1680 km; core state and composition are most consistent with a liquid metallic core and a density of ∼6.7 g/cm3. This implies a high S content (>20 wt%), assuming that S is the major alloying element. The most probable bulk Fe/Si ratio is ∼1.2, indicating that Mars most probably accreted from material with a nonchondritic (CI) Fe/Si ratio, such as the ordinary chondrites (L and LL), which also have oxygen isotopic ratios matching those in Martian meteorites.
Sea surface temperature and salinity variability at Bermuda during the end of the Little Ice Age
Authors: Goodkin Nathalie F. , Hughen Konrad A. , Curry William B. , Doney Scott C. , Ostermann Dorinda R.
Published: July 2008

We use geochemical and isotope measurements on a 225‐year old brain coral (Diploria labyrinthiformis) from the south shore of Bermuda (64°W, 32°N) to construct a record of decadal‐to‐centennial‐scale climate variability. The coral was collected alive, and annual density bands visible in X radiographs delineate cold and warm seasons allowing for precise dating. Coral skeletons incorporate strontium (Sr) and calcium (Ca) in relative proportions inversely to the sea surface temperature (SST) in which the skeleton is secreted. Previous studies on this and other coral colonies from this region document the ability to reconstruct mean annual and wintertime SST using Sr/Ca measurements (Goodkin et al., 2007, 2005). The coral‐based records of SST for the past 2 centuries show abrupt shifts at both decadal and centennial timescales and suggest that SST at the end of the Little Ice Age (between 1840 and 1860) was 1.5° ± 0.4°C colder than today (1990s). Coral‐reconstructed SST has a greater magnitude change than does a gridded instrumental SST record from this region. This may result from several physical processes including high rates of mesoscale eddy propagation in this region. Oxygen isotope values (δ18O) of the coral skeleton reflect changes in both temperature and the δ18O of seawater (δOw), where δOw is proportional to sea surface salinity (SSS). We show in this study that mean annual and wintertime δ18O of the carbonate (δOc) are correlated to both SST and SSS, but a robust, quantitative measure of SSS is not found with present calibration data. In combination, however, the Sr/Ca and δOc qualitatively reconstruct lower salinities at the end of the Little Ice Age relative to modern day. Temperature changes agree with other records from the Bermuda region. Radiative and atmospheric forcing may explain some of the SST variability, but the scales of implied changes in SST and SSS indicate large‐scale ocean circulation impacts as well.
Modeling blue and green water availability in Africa
Authors: Schuol Jürgen , Abbaspour Karim C. , Yang Hong , Srinivasan Raghavan , Zehnder Alexander J. B.
Published: July 2008

Despite the general awareness that in Africa many people and large areas are suffering from insufficient water supply, spatially and temporally detailed information on freshwater availability and water scarcity is so far rather limited. By applying a semidistributed hydrological model SWAT (Soil and Water Assessment Tool), the freshwater components blue water flow (i.e., water yield plus deep aquifer recharge), green water flow (i.e., actual evapotranspiration), and green water storage (i.e., soil water) were estimated at a subbasin level with monthly resolution for the whole of Africa. Using the program SUFI‐2 (Sequential Uncertainty Fitting Algorithm), the model was calibrated and validated at 207 discharge stations, and prediction uncertainties were quantified. The presented model and its results could be used in various advanced studies on climate change, water and food security, and virtual water trade, among others. The model results are generally good albeit with large prediction uncertainties in some cases. These uncertainties, however, disclose the actual knowledge about the modeled processes. The effect of considering these model‐based uncertainties in advanced studies is shown for the computation of water scarcity indicators.
Long‐Term Global Heating from Energy Usage
Authors: Chaisson Eric J.
Published: July 2008

Even if civilization on Earth stops polluting the biosphere with greenhouse gases, humanity could eventually be awash in too much heat, namely, the dissipated heat by‐product generated by any nonrenewable energy source. Apart from the Sun's natural aging—which causes an approximately 1% luminosity rise for each 108 years and thus about 1°C increase in Earths surface temperature—well within 1000 years our technological society could find itself up against a fundamental limit to growth: an unavoidable global heating of roughly 3°C dictated solely by the second law of thermodynamics, a biogeophysical effect often ignored when estimating future planetary warming scenarios.
Space Geodesy and the New Madrid Seismic Zone
Authors: Smalley Robert , Ellis Michael A.
Published: July 2008

One of the most contentious issues related to earthquake hazards in the United States centers on the midcontinent and the origin, magnitudes, and likely recurrence intervals of the 1811–1812 New Madrid earthquakes that occurred there. The stakeholder groups in the debate (local and state governments, reinsurance companies, American businesses, and the scientific community) are similar to the stakeholder groups in regions more famous for large earthquakes. However, debate about New Madrid seismic hazard has been fiercer because of the lack of two fundamental components of seismic hazard estimation: an explanatory model for large, midplate earthquakes; and sufficient or sufficiently precise data about the causes, effects, and histories of such earthquakes.
Extreme Weather: Understanding the Science of Hurricanes, Tornadoes, Floods, Heat Waves, Snow Storms, Global Warming and Other Atmospheric Disturbances
Authors: Brooks Harold
Published: July 2008

Extreme weather is of importance because of the threats it makes to life and property. At the same time, extreme weather is a great fascination for meteorologists as well as for the general public. The conditions and processes that lead to extreme weather—although governed by the same physical principles as “ordinary” weather—frequently are far from the average state of the atmosphere. Thus, explaining them in simple terms can be difficult. This book represents an effort to explain the development of extreme weather to the public.
Influence of observed mantle anisotropy on isotropic tomographic models
Authors: Lloyd S. M. , van der Lee S.
Published: July 2008

There is a potential for isotropic tomographic models to be biased by ignored anisotropy; anisotropy could be mapped as artificial isotropic velocity perturbations. We investigate the distribution and strength of this potential bias for three tomographic S velocity models based on regional S and Rayleigh waveforms. We use observed SKS delay times and fast‐axis orientations to compute equivalent S velocity perturbations for each wave path used for the tomographic models. These synthetic perturbations are then combined into a three‐dimensional isotropic model which reflects the potential bias in the actual tomographic model. We quantify anisotropic bias and find that it indeed exists in the isotropic tomographic models investigated here. This bias gets weaker with increasing depth of the anisotropic material, and compared to the isotropic velocity anomalies typically interpreted by tomographers, the bias from anisotropy is small.
Estimating pore‐space gas hydrate saturations from well log acoustic data
Authors: Lee Myung W. , Waite William F.
Published: July 2008

Relating pore‐space gas hydrate saturation to sonic velocity data is important for remotely estimating gas hydrate concentration in sediment. In the present study, sonic velocities of gas hydrate–bearing sands are modeled using a three‐phase Biot‐type theory in which sand, gas hydrate, and pore fluid form three homogeneous, interwoven frameworks. This theory is developed using well log compressional and shear wave velocity data from the Mallik 5L‐38 permafrost gas hydrate research well in Canada and applied to well log data from hydrate‐bearing sands in the Alaskan permafrost, Gulf of Mexico, and northern Cascadia margin. Velocity‐based gas hydrate saturation estimates are in good agreement with Nuclear Magneto Resonance and resistivity log estimates over the complete range of observed gas hydrate saturations.
Local wind system in the Rongbuk Valley on the northern slope of Mt. Everest
Authors: Zou Han , Zhou Libo , Ma Shupo , Li Peng , Wang Wei , Li Aiguo , Jia Jingjing , Gao Dengyi
Published: July 2008

To better understand the local wind systems in the Himalayas, wind and related atmospheric parameters were observed in the Rongbuk Valley on the northern slope of Mt. Everest, during the HEST2006 campaign, from May 29 to June 29, 2006. Data analysis and a simple numerical simulation show that the dominating down‐valley flow in this valley is mainly formed by the thermally driven winds, “valley wind”, “mountain wind” and “glacier wind”. The vertical air motion is composed of a descending flow from the morning to midnight and an ascending flow for the rest of the day, with important modification from the vertical component of the above down‐valley flow and a compensation flow of the “slope wind”. The analysis also shows that the local wind system is well confined in the Rongbuk Valley due to topographic shielding effects.
Ages of very large impact basins on Mars: Implications for the late heavy bombardment in the inner solar system
Authors: Frey Herbert
Published: July 2008

A sharp peak in both relative crater retention ages and inferred model absolute ages for the largest impact basins on Mars may be a Martian equivalent of a late heavy bombardment (LHB) terminal lunar cataclysm (TLC). If so, it supports a NICE‐type LHB, provides an important temporal connection between lunar and Martian chronologies, and suggests the current Martian chronology overestimates the age of large basins and perhaps other events in early Martian history.
Simultaneous measurements of particulate and gas‐phase water‐soluble organic carbon concentrations at remote and urban‐influenced locations
Authors: Anderson C. , Dibb J. E. , Griffin R. J. , Bergin M. H.
Published: July 2008

The sources, sinks, and overall importance of water‐soluble organic carbon (WSOC) in the atmosphere are not well understood. Although the primary historical focus has been on particulate WSOC (WSOCP), here we also present results obtained using a newly developed technique that additionally measures gas‐phase water‐soluble organic carbon (WSOCG). These first‐of‐their‐kind measurements show that WSOCG can often be more than ten times larger than WSOCP at both urban and remote locations. The average fraction of WSOC residing in the gas phase (fg = WSOCG/(WSOCG + WSOCP)) at five various field sites ranged from 0.64 to 0.93, implying significant differences in WSOC phase partitioning between locations. At Houston, TX, and Summit, Greenland, a repeatable diurnal pattern was observed, with minimum values for fg occurring at night. These trends likely are due, at least in part, to temperature and/or relative humidity related gas‐to‐particle partitioning. These coincident measurements of WSOC in both the gas and particle phases indicate that a relatively large reservoir of water‐soluble organic mass is not taken into account by measurements focused only on WSOCP. In addition, a significant amount of WSOCG is available to form WSOCP or enter cloud droplets depending on the chemical and physical properties of the droplets and/or aerosols present.
Initial‐stage pulses in upward lightning: Leader/return stroke versus M‐component mode of charge transfer to ground
Authors: Flache D. , Rakov V. A. , Heidler F. , Zischank W. , Thottappillil R.
Published: July 2008

We analyzed high‐speed video images and corresponding current records for eight upward lightning flashes initiated by the Peissenberg tower (160 m) in Germany. These flashes contained a total of 33 measurable initial stage (IS) current pulses, which are superimposed on steady IS currents. Seven IS pulses had relatively short (<8 μs) 10‐to‐90% risetimes and 26 IS pulses had relatively long (>8 μs) risetimes. Six (86%) of seven IS current pulses with shorter risetimes each developed in a newly‐illuminated branch, and 25 (96%) of 26 IS pulses with longer risetimes occurred in already luminous (current‐carrying) channels. These results support the hypothesis that longer risetimes are indicative of the M‐component mode of charge transfer to ground, while shorter risetimes are associated with the leader/return stroke mode. Similar results were obtained for M‐component pulses that are superimposed on continuing currents following return‐stroke pulses.
Seismic evidence for widespread serpentinized forearc mantle along the Mariana convergence margin
Authors: Tibi Rigobert , Wiens Douglas A. , Yuan Xiaohui
Published: July 2008

Seismic imaging of subduction zones can provide constraints on mineral reactions in the slab and surrounding regions. We use P‐to‐S converted phases from teleseisms recorded at broadband stations in the Mariana Islands to image the forearc and arc regions of the Mariana convergent margin. The subducting oceanic crust is observed between 75 and 110 km depth as a thin low velocity zone overlying the subducting Moho, demonstrating that the basalt to eclogite phase transition must occur at a greater depth. A low velocity zone (LVZ), approximately 10−25 km thick, whose upper boundary is imaged at about 40−55 km depth, is detected in the forearc region of the mantle wedge along the entire margin. The anomaly is located too shallow to represent subducted oceanic crust. We interpret the LVZ as a serpentinized region in the forearc mantle, resulting from hydration by slab‐expelled water. The inferred S‐wave velocity in the LVZ of as low as ∼3.6 km/s represents a level of serpentinization of 30−50%, corresponding to a chemically bound water content of about 4−6 wt%.