bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of deformation strain on the formation of banded clouds in idealized modelling experiments
Authors: Gray S. L. , Dacre H. F.
Published: June 2008

Experiments are performed using an idealized version of an operational forecast model to determine the impact on banded frontal clouds of the strength of deformational forcing, low‐level baroclinicity, and model representation of convection. Line convection is initiated along the front, and slantwise bands extend from the top of the line‐convection elements into the cold air. This banding is attributed primarily to ΔM adjustment. The cross‐frontal spreading of the cold pool generated by the line convection leads to further triggering of upright convection in the cold air that feeds into these slantwise bands. Secondary low‐level bands form later in the simulations; these are attributed to the release of conditional symmetric instability. Enhanced deformation strain leads to earlier onset of convection and more coherent line convection. A stronger cold pool is generated, but its speed is reduced relative to that seen in experiments with weaker deformational strain, because of inhibition by the strain field. Enhanced low‐level baroclinicity leads to the generation of more inertial instability by line convection (for a given capping height of convection), and consequently greater strength of the slantwise circulations formed by ΔM adjustment. These conclusions are based on experiments without a convective‐parametrization scheme. Experiments using the standard or a modified scheme for this model demonstrate known problems with the use of this scheme at the awkward 4 km grid length used in these simulations. Copyright © 2008 Royal Meteorological Society
Atmospheric turbulence component of the innovation covariance
Authors: Frehlich Rod
Published: June 2008

The innovation covariance is derived for general atmospheric turbulence conditions and for climatologies of upper‐level turbulence based on aircraft data. Error is defined in terms of the effective spatial filter of the forecast model to produce a consistent definition of measurement error and model error. Calculations of the atmospheric turbulence component (observation sampling‐error covariance) are performed for rawinsonde data and various forecast model resolutions. Significant contributions from the atmospheric turbulence field are produced, especially for the older forecast models. Copyright © 2008 Royal Meteorological Society
Fuzzy approach to dependability performance evaluation
Authors: Ivezić Dejan , Tanasijević Miloš , Ignjatović Dragan
Published: June 2008

This paper presents a model for dependability performance evaluation by fuzzy sets utilization. Basic dependability indicators (reliability, maintainability and maintenance support) are used for the analysis of technical systems' conditions from the aspects of design, construction, maintenance and logistics. These indicators as well as associated dependability expressions itself are described by linguistic variables, which are characterized by a membership function to the defined classes. The proposed model is primarily appropriate for introduction, analysis and synthesis of information related to quality of systems in operation. Such data are often available only as experts' judgment and estimations. A practical engineering example (mechanical system at bucket wheel excavator) has been presented to demonstrate the proposed dependability analysis and synthesis model. Copyright © 2008 John Wiley & Sons, Ltd.
Biorthogonal method of moments of coupled‐cluster equations: Alternative derivation, further considerations, and application to a model magnetic system
Authors: Piecuch Piotr , Gour Jeffrey R. , Włoch Marta
Published: June 2008

The energy expansion defining the biorthogonal method of moments of coupled‐cluster equations (MMCC) [Piecuch and Włoch, J Chem Phys, 2005, 123, 224105 and Piecuch et al., Chem Phys Lett 2006, 418, 467], which leads to the size extensive completely renormalized (CR) coupled‐cluster (CC) approach with singles, doubles, and noniterative triples employing the left eigenstates of the similarity‐transformed Hamiltonian, termed CR‐CC(2,3), is overviewed and rederived. The rederivation of the biorthogonal MMCC expansion presented in this work is based on a direct resummation and subsequent elimination of the many‐body components of the exponential wave operator of CC theory that appear at individual moment contributions in the original MMCC energy expansion [Kowalski and Piecuch, J Chem Phys, 2000, 113, 18; Kowalski and Piecuch, J Chem Phys 2001, 115, 2966], enabling one to understand why the CR‐CC(2,3) method using the biorthogonal MMCC theory is more accurate than the earlier CR‐CCSD(T) approach. The superiority of the CR‐CC(2,3) method over the CR‐CCSD(T) and other previously developed single‐reference CC methods with a noniterative treatment of triply excited clusters, including the widely used CCSD(T) approach and the triples corrections defining the CCSD(2) schemes, is illustrated by examining the singlet–triplet gap of the (HFH)− magnetic system in which two paramagnetic centers are linked via a polarizable diamagnetic bridge. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Microfluidics‐based electrospray ionization enhances the intrasource separation of lipid classes and extends identification of individual molecular species through multi‐dimensional mass spectrometry: development of an automated high‐throughput platform for shotgun lipidomics
Authors: Han Xianlin , Yang Kui , Gross Richard W.
Published: June 2008

Herein, we exploit the use of microfluidics and optimized Taylor cones for improved intrasource separation/selective ionization of lipid classes during electrospray ionization. Increased differential ionization of multiple phospholipid classes was achieved through microfluidics with chip‐based ionization resulting in substantial enhancement of intrasource separation/selective ionization of phospholipid classes in comparison to the conventional ion source. For example, using myocardial lipid extracts, 3‐fold improvements in intrasource separation/selective ionization of myocardial phospholipid classes were routinely realized in the negative‐ion mode in the absence of LiOH or other basic modifiers in the infused sample solutions. Importantly, the relative ratios of ions corresponding to individual molecular species in each lipid class to a selected internal standard from myocardial extracts were nearly identical between the chip‐based interface and the syringe‐pump‐driven capillary interface. Therefore, quantitation of individual lipid molecular species directly from biological extracts through comparisons with internal standards in each lipid class was readily accomplished with an accuracy and dynamic range nearly identical to those documented using the well‐established direct syringe‐pump‐driven capillary interface. Collectively, the use of microfluidics and robotic sample handling substantially enhances intrasource separation of lipids in comparison to routine capillary interfaces and greatly facilitates the use of multi‐dimensional mass spectrometry using shotgun lipidomics, thereby providing an automated and high‐throughput platform for global analyses of cellular lipidomes. Copyright © 2008 John Wiley & Sons, Ltd.
Das Letzigrundstadion in Zürich
Authors: Galmarini Carlo , Schollmayer Martin , Mensinger Martin
Published: June 2008

Im August 2007 wurde nach einer Rekordbauzeit von ca. 1 1/2 Jahren das Letzigrundstadion in Zürich fertiggestellt. Eine der großen Veranstaltungen, die in diesem Stadion stattfinden werden, ist die Fußballeuropameisterschaft Euro 08. Allerdings ist das Letzigrund kein reines Fußball‐ sondern ein Mehrzweckstadion, in dem auch das jährliche Leichtathletikmeeting “Weltklasse Zürich” und Konzerte stattfinden werden. Anders als viele Stadionneubauten wurde es nicht außerhalb der Stadt, sondern mitten in einer Wohngegend gebaut. Eine Intention des Architekten war es deshalb, das Stadion sehr offen zu gestalten, was auch sehr hohe Anforderungen an die Ingenieure bei der Umsetzung der Dachkonstruktion stellte.
Ingenieurmodell zum ungewöhnlichen Tragverhalten einzelliger Rechteckkästen mit linear veränderlicher Bauhöhe unter Torsionsbeanspruchung
Authors: Unterweger Harald
Published: June 2008

Einzellige prismatische Kastenträger erhalten aus Torsionsbeanspruchung, wenn im Krafteinleitungsbereich Queraussteifungen vorliegen, nahezu nur eine reine Schubbeanspruchung. Weist der Kastenträger hingegen eine linear veränderliche Bauhöhe auf, ergeben sich deutliche nderungen im Schubbeanspruchungsverlauf, und es treten zusätzliche hohe Wölbnormalspannungen auf. Letztere sind nicht vernachlässigbar, da sie zum Gleichgewicht beitragen und nicht durch Plastizieren – wie beim prismatischen Kasten – abgebaut werden können. Dieses Tragverhalten führt auch zu deutlich größeren Verformungen bzw. Stabverdrehungen, da sich nun auch Querschnittsverformungen einstellen.

Nachfolgend wird das ungewöhnliche Tragverhalten anhand von Einzelbeispielen kurz dargestellt. Den Schwerpunkt dieses Beitrags bildet die Vorstellung eines Ingenieurmodells, das es gestattet, Größe und Verlauf der hohen Wölbnormalspannungen und Schubspannungen (in Längsrichtung und entlang der Querschnittswandungen) anhand aufbereiteter Formeln zutreffend zu ermitteln. Dabei wird auch der zweiachsige Spannungszustand im Bereich der Querschnittskante mit erfasst. Darüber hinaus werden auch Formeln angegeben, um die Stabverdrehungen und die Verwölbungen an den Trägerenden abzuschätzen. Die Treffsicherheit dieser ingenieurmäßigen Näherungen wurde anhand von umfangreichen FE‐Berechnungen überprüft und kalibriert.
Tragfähigkeit fehlerhafter Schweißnähte
Authors: Hölbling Wolfram , Saal Helmut
Published: June 2008

Aktuelle Bemessungsregeln für Schweißnähte gelten nur dann, wenn die Nähte gemäß den Anforderungen in den zugehörigen Ausführungsregeln hergestellt werden. Alle Ausführungsregeln schließen bestimmte Nahtungänzen wie Bindefehler auch bei vorwiegend ruhender Beanspruchung aus.

Die im Stahlbau verarbeiteten maximalen Erzeugnisdicken haben in jüngerer Zeit beträchtlich zugenommen. Das Schweißnahtvolumen und somit die Arbeitskosten für das Schweißen nehmen mit zunehmender Erzeugnisdicke etwa quadratisch zu. Wenn immer es rechnerisch möglich ist, reduzieren die Fertigungsbetriebe deshalb das Nahtvolumen durch teilweise anstatt voll durchgeschweißte Nähte und durch möglichst kleine Nahtöffnungswinkel. Insbesondere bei großen Erzeugnisdicken sind wegen der schlechten Zugänglichkeit der Nahtwurzel Bindefehler nicht sicher auszuschließen. Der Nachweis der Tragfähigkeit von Nähten mit Bindefehlern kann bisher nicht erbracht werden.

Zur Beseitigung dieses Hindernisses werden experimentelle, numerische und bruchmechanische Untersuchungen durchgeführt, die den Einfluss von Ungänzen auf die Nahttragfähigkeit für unterschiedliche Nahtausführungen zeigen.
Decreasing the cost of mutation testing with second‐order mutants
Authors: Polo Macario , Piattini Mario , García‐Rodríguez Ignacio
Published: June 2008

Although powerful, mutation is a computationally very expensive testing technique. In fact, its three main stages (mutant generation, mutant execution and result analysis) require many resources to be successfully accomplished. Thus, researchers have made important efforts to reduce its costs. This paper represents an additional effort in this sense. It describes the results of two experiments in which, by means of combining the original set of mutants and therefore obtaining a new set of mutants—each one with two faults—the number of mutants used is reduced to half. Results lead to believe that mutant combination does not decrease the quality of the test suite, whereas it supposes important savings in mutant execution and result analysis. Copyright © 2008 John Wiley & Sons, Ltd.
Structural coverage criteria for LUSTRE/SCADEprograms
Authors: Lakehal Abdesselam , Parissis Ioannis
Published: June 2008

LUSTREis a data‐flow synchronous language, on which is based the SCADEtool‐suite, widely used for specifying and programming critical reactive applications in the areas of avionics, energy or transport. Therefore, testing LUSTREprograms, that is, generating test data and assessing the achieved test coverage, is a major issue. Usual control‐flow‐based test coverage criteria (statement coverage, branch coverage, etc.) are not relevant for LUSTREprograms. In this paper, a new hierarchy of adequacy criteria tailored to the LUSTRElanguage is presented. These criteria are defined on operator networks, which are usual models for LUSTREprograms. The criteria satisfaction measure is automated in LUSTRUCTU, a non‐intrusive tool (no instrumentation of the code), based on the symbolic computation of path activation conditions. The applicability and the relevance of the criteria are assessed on a case study. Copyright © 2008 John Wiley & Sons, Ltd.
Pain in childbirth and postpartum recovery – The role of catastrophizing
Authors: Flink Ida K. , Mroczek Magdalena Z. , Sullivan Michael J.L. , Linton Steven J.
Published: June 2008

This prospective study investigated how pain catastrophizing was related to labor pain intensity and physical recovery after childbirth. Eighty‐eight women giving birth for the first time completed the first questionnaire before delivery. Eighty‐two of those returned the second questionnaire after delivery. Participants were classified as catastrophizers (n=38) or non‐catastrophizers (n=44) based on their scores on the Pain Catastrophizing Scale. Comparison of the groups showed that catastrophizers anticipated and experienced more intense pain (p<.0125) and had poorer physical recovery (p<.0125), measured as the level of self‐reported functioning in activities of daily living, than non‐catastrophizers. These results extend the association between catastrophizing and pain, to pain and recovery in childbirth and provide support for the fear‐avoidance model. It is concluded that pain catastrophizing plays a role in the experience of pain in childbirth and postpartum recovery. Further research is needed to identify appropriate interventions for catastrophizing women during the latter part of pregnancy.
A study of neuropsychological deficit in children with obsessive-compulsive disorder
Authors: Shin Min-Sup , Choi Hyunjung , Kim Hana , Hwang Jun-Won , Kim Boong-Nyun , Cho Soo-Churl
Published: June 2008

This study was conducted to examine the neuropsychological deficits in children with obsessive compulsive disorder (OCD). Furthermore, the focus of present study was to explore whether OCD children show the same executive dysfunction as adult OCD patients. The participants consisted of 106 children between the ages of 6 and 16 years who visited the department of child-adolescent psychiatry, Seoul National University Children's Hospital (17 OCD, 25 ADHD, 21 tic disorder, 20 depressive disorder, and 23 healthy children). The OCD children showed higher verbal ability compared to other psychiatric groups, but performed the worst on WISC-R subtests assessing perceptual organization ability under time pressure. The OCD children did not show any significant deficits in verbal intellectual function, memory, attention and concentration abilities. However, similar to the ADHD children, the OCD children had significantly more errors and completed fewer categories on the WCST compared to the healthy group. Through neuropsychological tests, the OCD children showed cognitive strength and weakness similar to those of OCD adults that were reported in previous research. Specifically, they had executive function deficits in mental set shifting, supporting the frontal-striatal dysfunction hypothesis of OCD in children as well as in adults.
Thymosin β4 is involved in stabilin‐2‐mediated apoptotic cell engulfment
Authors: Lee Sung-Jin , So In-Seop , Park Seung-Yoon , Kim In-San
Published: June 2008

MINT‐6542321, MINT‐6542357:

Stab2-c (uniprotkb:Q8WWQ8) physically interacts (MI:0218) with tb4 (uniprotkb:P20065) by anti tag coimmunoprecipitation (MI:0007)

MINT‐6542368:

Stab2-c (uniprotkb:Q8WWQ8) physically interacts (MI:0218) with tb4 (uniprotkb:P20065) by pull down (MI:0096)

MINT‐6542300:

Stab2-c (uniprotkb:Q8WWQ8) physically interacts (MI:0218) with tb4 (uniprotkb:P62328) by two hybrid (MI:0018)
Gramicidin S identified as a potent inhibitor for cytochrome bd‐type quinol oxidase
Authors: Mogi Tatsushi , Ui Hideaki , Shiomi Kazuro , Ōmura Satoshi , Kita Kiyoshi
Published: June 2008

Gramicidin S, a cationic cyclic decapeptide, exhibits the potent antibiotic activity through perturbation of lipid bilayers of the bacterial membrane. From the screening of natural antibiotics, we identified gramicidin S as a potent inhibitor for cytochrome bd‐type quinol oxidase from Escherichia coli. We found that gramicidin S inhibited the oxidase with IC50 of 3.5 μM by decreasing V
max and the affinity for substrates but showed the stimulatory effect at low concentrations. Our findings would provide a new insight into the development of gramicidin S analogs, which do not share the target and mechanism with conventional antibiotics.
Isoform‐specific interaction of pyruvate kinase with hepatitis C virus NS5B
Authors: Wu Xiaoyun , Zhou You , Zhang Ke , Liu Qingzhen , Guo Deyin
Published: June 2008

MINT‐6548876, MINT‐6548924:

NS5B(Con1) (uniprotkb:Q9WMX2) and M2PK (uniprotkb:P14618) colocalize (MI:0403) by fluorescence microscopy (MI:0416)

MINT‐6548705:

NS5BΔ21(BK) (uniprotkb:P26663) physically interacts (MI:0218) with M2PK (uniprotkb:P52480) by two hybrid (MI:0018)

MINT‐6548722, MINT‐6548746:

CM2PK (uniprotkb:P52480)binds (MI:0407) to NS5BΔ21(BK) (uniprotkb:P26663) by pull down (MI:0096)

MINT‐6548831:

M2PK (uniprotkb:P14618) physically interacts (MI:0218) with NS5B (Con1) (uniprotkb:Q9WMX2) by anti bait coimmunoprecipitation (MI:0006)

MINT‐6548795:

M2PK (uniprotkb:P14618) physically interacts (MI:0218) with NS5B(Con1) (uniprotkb:Q9WMX2)by anti tag coimmunoprecipitation (MI:0007)

MINT‐6548852:

M2PK (uniprotkb:P14618) and NS5BΔ21(BK) (uniprotkb:P26663) colocalize (MI:0403) by fluorescence microscopy (MI:0416)
Deregulation of PKN1 activity disrupts neurofilament organisation and axonal transport
Authors: Manser Catherine , Stevenson Alison , Banner Steven , Davies Jennifer , Tudor Elizabeth L. , Ono Yoshitaka , Nigel Leigh P. , McLoughlin Declan M. , Shaw Christopher E. , Miller Christopher C.J.
Published: June 2008

Neurofilaments are synthesised in neuronal cell bodies and then transported through axons. Damage to neurofilament transport is seen in amyotrophic lateral sclerosis (ALS). Here, we show that PKN1, a neurofilament head–rod domain kinase is cleaved and activated in SOD1G93A transgenic mice that are a model of ALS. Moreover, we demonstrate that glutamate, a proposed toxic mechanism in ALS leads to caspase cleavage and disruption of PKN1 in neurons. Finally, we demonstrate that a cleaved form of PKN1 but not wild‐type PKN1 disrupts neurofilament organisation and axonal transport. Thus, deregulation of PKN1 may contribute to the pathogenic process in ALS.
Domain versatility in plant AB‐toxins: Evidence for a local, pH‐dependent rearrangement in the 2γ lectin site of the mistletoe lectin by applying ligand derivatives and modelling
Authors: Jiménez Marta , André Sabine , Barillari Caterina , Romero Antonio , Rognan Didier , Gabius Hans-Joachim , Solís Dolores
Published: June 2008

Mistletoe lectin is a potent biohazard. Lectin activity in the toxic dimer primarily originates from the 2γ‐subdomain (Tyr‐site) of the B‐subunit. Crystallographic information on lectin–sugar complexes is available only at acidic pH, where lectin activity is low. Thus, we mapped ligand‐binding properties including comparison to ricin's Tyr‐site at neutral pH. Using these results and molecular dynamics simulations, a local conformational change was rendered likely. The obtained structural information is valuable for the design of potent inhibitors.
Infectivity ofEchinococcus granulosusprotoscolices under different conditions of temperature and humidity
Authors: Diker A.I. , Tinar R. , Senlik B.
Published: June 2008

The aim of this study was to examine the effect of different temperatures and humidities on the infectivity ofEchinococcus granulosusprotoscolices. Eighteen dogs (6 groups,n = 3 each) were fed with offal mince harbouring approximately 20,000 protoscolices ofE. granulosusof different viabilities. Dogs were infected withE. granulosusprotoscolices of: (1) 5% viability at − 10°C and 50% relative humidity (RH); (2) 30% viability at 0°C and 60% RH; (3) 20% viability at +10°C and 65% RH; (4) 15% viability at +30°C and 75% RH; (5) 11% viability at +40°C and 80% RH; (6) 68% viability (control group). Dogs in each group were necropsied at 29–49 days post-infection. Mean intensities ofE. granulosusrecovered from dogs were 256.7 ± 60.3 in the second group; 32.7 ± 7.1 in the third group; 40.3 ± 15.5 in the fourth group and 1533 ± 513 in the control group. However, no parasites were recovered from the first and fifth groups. Results obtained in the present study show that larval stages could be infective for 1 to 4 weeks during spring, autumn or winter months when maximal temperatures are approximately 0–10°C. In conclusion, cold-storage depots in slaughterhouses and abattoirs where sheep carcasses might be discarded should be kept at − 20°C for 2–3 days, dogs should be properly controlled and adequate control programmes must be established in areas where the disease is endemic.
Potential role of the glial water channel aquaporin-4 in epilepsy
Authors: Hsu Mike S. , Lee Darrin J. , Binder Devin K.
Published: June 2008

Recent studies have implicated glial cells in novel physiological roles in the CNS, such as
modulation of synaptic transmission, so it is possible that glial cells might have a functional
role in the hyperexcitability that is characteristic of epilepsy. Indeed, alterations in
distinct astrocyte membrane channels, receptors and transporters have all been associated with
the epileptic state. This paper focuses on the potential roles of the glial water channel
aquaporin-4 (AQP4) in modulating brain excitability and in epilepsy. We review studies of
seizure phenotypes, K+ homeostasis and extracellular space physiology of mice that
lack AQP4 (AQP4−/− mice) and discuss the human studies
demonstrating alterations of AQP4 in specimens of human epilepsy tissue. We conclude with new
studies of AQP4 regulation by seizures and discuss its potential role in the development of
epilepsy (epileptogenesis). Although many questions remain unanswered, the available data
indicate that AQP4 and its molecular partners might represent important new therapeutic
targets.
Radiation of ELF/VLF waves by harmonically varying currents into a stratified ionosphere with application to radiation by a modulated electrojet
Authors: Lehtinen N. G. , Inan U. S.
Published: June 2008

We use a full‐wave finite element approach inspired by the mode calculation method of Wait (1970) to calculate electromagnetic fields in a horizontally stratified ionosphere treated as a magnetized plasma. The source currents can have arbitrary vertical and horizontal distributions. The electromagnetic field is calculated both in the Earth‐ionosphere waveguide (at arbitrary horizontal distance and direction) and in the ionosphere (as an upward propagating whistler mode wave). This method requires less computational resources than traditional FDFD and FDTD methods, while providing results with similar accuracy. The model is applied to the radiation of ELF/VLF waves from modulated HF‐heated electrojet currents, and the calculated values are compared to ground and satellite observations.
Localized analysis of satellite tracking data for studying time‐variable Earth's gravity fields
Authors: Han Shin‐Chan , Rowlands David D. , Luthcke Scott B. , Lemoine Frank G.
Published: June 2008

We present a method to analyze the observations of relative distance change between two low Earth orbiting satellites of the Gravity Recovery And Climate Experiment (GRACE) mission after removing the effects caused by the mean gravity field and better‐known temporal mass redistribution. The gravitational acceleration exerted by the block mean mass within a region on the Earth surface is formulated by point mass approximation and by spherical harmonic expansion. In addition to the regional mass parameters, the arc‐dependent parameters (initial relative state vectors) is simultaneously modeled to remove the signals not associated with the mass variation within the focus area. While a certain level of approximation, that is committed when locally formulating the gravitational acceleration vector for numerical integration, causes model error, we benefit from regionally estimating time‐variable mass with improved spatial and temporal resolutions. In addition, various temporal parameterizations depending on geographical areas and expected signals can be applied for the regional analysis in a straightforward manner and it helps to retrieve even sub‐daily time‐variable signals such as tides from many years of GRACE data. We present the results of hydrology and ocean tide recovery in South America, Africa, North America, and Antarctica from the analysis of 3.5 years of GRACE tracking data and compare them with the traditional global harmonic approach. The algorithm development thoroughly described here will be helpful for the science community to exploit fundamental data (range rate) of the GRACE mission in addition to monthly gravity products.
Five years of Florida Current structure and transport from the Royal Caribbean Cruise Ship Explorer of the Seas
Authors: Beal Lisa M. , Hummon Julia M. , Williams Elizabeth , Brown Otis B. , Baringer Warner , Kearns Edward J.
Published: June 2008

Using ship‐of‐opportunity platform Explorer of the Seas, five years of full‐depth velocity data have been collected across the Florida Straits at 26°N. Between May 2001 and May 2006 the mean transport of the Florida Current was 31.0 ± 4.0 Sv. This compares to a mean transport of 32.4 ± 3.2 Sv inferred from cable voltages at 27°N over the same period, implying an average 1.4 Sv transport into the Straits through the Northwest Providence Channel. The climatological core of the Florida Current is 170 cms−1 and is positioned at 79.8°W, about 10 km east of the shelf break. The largest variability in velocity occurs over the shelf and shelf break and is likely related to shelf waves. A secondary maximum occurs across much of the Straits over the top 100 m of the water column and may be associated with wind events. The annual cycle of Florida Current transports has a range of 4.7 Sv, with a maximum in May–June–July and a minimum in January. The difference between the summer and winter current structure appears as a first baroclinic mode with zero crossing at 150 m. The maximum difference is about 15 cms−1 at the surface and is centered just offshore of the mean current core. On interannual timescales, low‐pass filtered Explorer and cable transports show similar downward trends between 2002 and 2005, but diverge over the last year or so of the record.
Remotely forced biweekly deep oscillations on the continental slope of the Gulf of Guinea
Authors: Guiavarc'h Catherine , Treguier Anne Marie , Vangriesheim Annick
Published: June 2008

Current meter measurements on the continental slope of the Gulf of Guinea (at 7°20′S and 1300 m depth) have revealed biweekly oscillations of the currents, bottom intensified and oriented along the bathymetry. We develop a three‐dimensional primitive equation model of the Gulf of Guinea to study the oscillations and their forcing mechanism. The high resolution (1/12°) regional model reproduces remarkably well the main characteristics of the deep currents on the continental slope. Experiments with different forcings demonstrate that the biweekly variability at 1300 m depth is remotely forced by equatorial winds. Deep Yanai waves generated by the wind propagate eastward along the equator. Upon reaching the African coast, the energy propagates poleward in both directions as coastal trapped waves. The selection of the dominant biweekly period is explained by the absence of equatorial waves with westward group velocities in that frequency band. Contrary to a previous hypothesis involving tidal forcing, our interpretation is coherent with the significant interannual variability of the biweekly energy.
Observed equatorial Rossby waves and ENSO‐related warm water volume changes in the equatorial Pacific Ocean
Authors: Bosc Christelle , Delcroix Thierry
Published: June 2008

Modifications of the volume of warm water above the thermocline in the equatorial Pacific are thought to be critical for ENSO (El Niño Southern Oscillation) preconditioning, development and prediction. In this paper, changes in this Warm Water Volume (WWV) are first reviewed from the literature, and then analyzed within 5°N–5°S in using 1992–2006 altimeter‐derived sea level anomalies (SLA) and in situ observations. We conclude that the 1992–2006 WWV changes in the equatorial band are a residual from the opposite effects of zonally integrated meridional Ekman and geostrophic transports of warm water, the latter being estimated from SLA and validated against in situ observations. For the first time with observations, we evidence first baroclinic first meridional mode equatorial Rossby waves to be responsible for the anomalous meridional geostrophic transports of warm water, in changing the basin‐scale zonal pressure gradient. These transports appear in phase opposition and proportional to the anomalous Sea Surface Temperature (SST) in the region NIÑO3.4 (170°W–120°W, 5°N–5°S). The links between our observational results and the recharge/discharge oscillator theory, the differences in WWV between ENSO events, and the hint for possible recent changes in the relation between WWV and NIÑO3.4 SST are discussed.
Atlantic and Pacific SST influences on Medieval drought in North America simulated by the Community Atmospheric Model
Authors: Feng Song , Oglesby Robert J. , Rowe Clinton M. , Loope David B. , Hu Qi
Published: June 2008

Severe drought is arguably one of the greatest recurring natural disasters that strikes North America. A synthesis of multiproxy data shows that North America was in the grip of a severe centennial‐scale drought during medieval times (800–1300 AD). In this study, the Community Atmospheric Model (CAM) is used to investigate the role of sea surface temperature (SST) anomalies from the North Atlantic and the tropical Pacific Ocean on this megadrought. These anomalies are obtained from proxy reconstructions of SST. Four model experiments with prescribed SST anomalies in the tropical Pacific and/or North Atlantic Ocean were made. The CAM results captured the major dry features that occurred during medieval times in North America. The cold tropical Pacific alone can simulate essentially the drought intensity, while the warm North Atlantic alone can simulate the drought areal extent. The two working together can explain the severity and longevity of the drought. During the spring season, the cool tropical Pacific, or the warm North Atlantic, or both, results in less moisture transport to the High Plains, with a 15–40% decrease in rainfall. The importance of the Atlantic Ocean on medieval drought in North America suggests that attention should be paid not only to the tropical Pacific Ocean but also to the North Atlantic Ocean in understanding the North America drought variability and predictability, both at present and during the past. This is especially true because the Pacific Ocean SST anomalies in medieval times as recorded by proxy data are somewhat controversial, while the North Atlantic anomalies seem more certain.
CO2 retrievals from the Atmospheric Infrared Sounder: Methodology and validation
Authors: Maddy E. S. , Barnet C. D. , Goldberg M. , Sweeney C. , Liu X.
Published: June 2008

In this paper we describe the methodology of an offline retrieval of CO2 from AIRS data and show comparisons of these retrievals with all available NOAA ESRL/GMD aircraft data during 2005. In general, we find that when compared to the aircraft the AIRS CO2 estimates agree to approximately ±0.5% in middle‐tropospheric CO2 column abundances between ±65 degrees latitude.
Seismic reflection evidence for a Dangerous Grounds miniplate: No extrusion origin for the South China Sea
Authors: Clift Peter , Lee Gwang H. , Anh Duc Nguyan , Barckhausen Udo , Van Long Hoang , Zhen Sun
Published: June 2008

The collision of India and Asia has caused large strike‐slip faults to form in east Asia, resulting in the “extrusion” of crustal blocks toward the southeast since the Eocene as a result of the indentation of rigid India into Asia. It has been suggested that the South China Sea opened as a result of relative motion between a rigid Indochina (Sundaland) block and China. Alternative models propose that rifting and seafloor spreading were driven by trench forces to the south. We test these competing models by analysis of seismic reflection profiles across the boundary between Sundaland and the southern rifted margin, known as the Dangerous Grounds. We show that the southern boundary of the Dangerous Grounds is a subduction zone that jammed in the middle Miocene. To the west the Dangerous Grounds are bounded by a strike‐slip zone, also active until ∼16 Ma, that becomes diffuse south of the now inactive South China Sea seafloor spreading center. We place the western edge of the Dangerous Grounds just to the east of the Natuna Arch (Lupar Line). The West Baram Line is confirmed as originating as a major strike‐slip fault within the Dangerous Grounds and is continuous with the Red River Fault Zone. Because the Dangerous Grounds were independent of Sundaland until ∼16 Ma, its motion cannot have been constrained by motion of this block, making extrusion impossible as a mechanism to rift the South China Sea. SE motion by both the Dangerous Grounds and Sundaland suggests subduction forces were the primary trigger for plate motions. Our reconstruction places a ∼280 km upper limit on the motion on the Red River Fault and a ∼1400 km width to the paleo–South China Sea.
Microbial activity in surficial sediments overlying acoustic wipeout zones at a Gulf of Mexico cold seep
Authors: Lapham Laura L. , Chanton Jeffrey P. , Martens Christopher S. , Sleeper Ken , Woolsey J. Robert
Published: June 2008

Down core concentration gradients of dissolved methane and sulfate; isotope gradients of methane, dissolved inorganic carbon, and authigenic carbonate; and organic matter elemental ratios are incorporated into a vent evolution model to describe spatial and temporal variability of sedimentary microbial activity overlying acoustic wipeout zones at Mississippi Canyon (MC) 118, Gulf of Mexico. We tested the hypothesis that these zones indicate areas where sediments are exposed to elevated fluid flux and therefore should contain saturated methane concentrations and enhanced microbial activity from sulfate reduction (SR), anaerobic oxidation of methane (AOM), and methanogenesis (MP). Thirty surficial cores (between 22 and 460 cm deep) were collected from sediments overlying and outside the wipeout zones and analyzed for pore water and solid phase constituents. Outside the wipeout zones, sulfate and methane concentrations were similar to overlying‐water values and did not vary with depth; indicating low microbial activity. Above the wipeouts, nine cores showed moderate activity with gently sloping sulfate and methane concentration gradients, methane concentrations <20 μM, and isotope depth gradients indicative of organic matter oxidation. In stark contrast to this moderate activity, four cores showed high microbial activity where sulfate concentrations were depleted by ∼50 cm below seafloor, maximum methane concentrations in the decompressed cores were above 4 mM, and down core profiles of δ13C‐CH4 and δ13C‐dissolved inorganic carbon (DIC) indicated distinct depth zones of SR, AOM, and MP. Bulk organic matter analysis suggested that the high activity was supported by an organic source that was enriched in carbon (C:N ∼15) and depleted in δ15N and δ13C compared to other activity groups, possibly due to the influx of petroleum or chemosynthetically fixed carbon. Within high activity cores, the δ13C‐DIC values were similar to the δ13C‐CaCO3 values, a result expected for authigenic carbonate recently precipitated. However, these values were dissimilar in moderate activity cores, suggesting that microbial activity was higher in the past. This study provides evidence that the fluid flux at MC 118 varies over time and that the microbial activity responds to such variability. It also suggests that sediments overlying wipeout zones are not always saturated with respect to methane, which has implications for the formation and detection of gas hydrate.
Laboratory‐measured nucleation rates of sulfuric acid and water binary homogeneous nucleation from the SO2 + OH reaction
Authors: Benson David R. , Young Li‐Hao , Kameel F. Rifkha , Lee Shan‐Hu
Published: June 2008

We have measured H2SO4‐H2O nucleation rates (J) at atmospheric pressure, 288 K and 10–55 % relative humidity (RH). H2SO4 was produced from the SO2 + OH → HSO3 reaction and was measured with a chemical ionization mass spectrometer (CIMS). The CIMS‐measured [H2SO4] that is required to produce the unit J ranged from 107–108 cm−3, but if wall loss is taken into account the threshold [H2SO4] was at the 108–109 cm−3 range, much higher than the atmospheric conditions. The measured J was proportional to [H2SO4] with the second to tenth powers and proportional to RH with the eleventh to fifteenth powers. The measured aerosol sizes were proportional to log RH, showing a weak dependence of aerosol growth on RH. But the RH effects were more pronounced at higher [H2SO4], indicating that RH is more important for aerosol growth in the H2SO4 rich environment.
Interdependence of magnetic field and plasma pressures in cusp diamagnetic cavities
Authors: Niehof Jonathan T. , Fritz Theodore A. , Friedel Reiner H. W. , Chen Jiasheng
Published: June 2008

We examine Polar data for several high‐altitude cusp crossings to characterize “Cusp Diamagnetic Cavities” (CDCs). In particular, we determine the relationship between the magnetic field and thermal pressure of the local plasma. The cusp is characterized by high density and the presence of stagnant solar wind plasma throughout. The CDCs represent a distinct region within the cusp, possessing a depressed and turbulent magnetic field in addition to the other cusp properties. We find the CDCs are colocated with “Cusp Energetic Particle” (CEP) events. In CDCs, depressions in the field are strongly correlated to local enhancements in plasma density and thus pressure, supporting the “diamagnetic” label. No correlation between field and plasma is found in the cusp outside of the CDC. The colocation of CDCs and CEP events suggests constraints on the origin of CEPs.
Prophages in marine bacteria: dangerous molecular time bombs or the key to survival in the seas?
Authors: Paul John H
Published: June 2008

Bacteriophages are realized to be numerous and important components of oceanic food webs principally because of their lytic capabilities. The subtle changes that temperate phages impart to their hosts in the oceans are far less understood. Occurrences of lysogeny in the oceans correlate well with conditions unfavorable for rapid host growth. In coliphage λ, phage encoded repressors have been shown to modulate host metabolic gene expression and phenotype, resulting in economizing host energy expenditure. Comparison of lysogenized marine bacteria to the uninfected hosts indicated that prophage acquisition is correlated with host metabolic gene suppression. Screening 113 marine bacterial genomes for prophages yielded 64 prophage-like elements, 21 of which strongly resembled gene transfer agents (GTAs). The remaining 39 putative prophages had a relatively high incidence of transcriptional regulatory and repressor-like proteins (∼2/40 kb prophage sequence) compared to lytic marine phages (∼0.25/40 kb phage sequence). Here, it has been hypothesized that marine prophages directly contribute to host survival in unfavorable environments by suppression of unneeded metabolic activities. It has been further suggested that such metabolic downshifts are the result of phage-encoded repressors and transcriptional regulators acting directly on host genes. Finally, the widespread occurrence of GTAs may be an efficient mechanism for horizontal gene transfer in the oceans.
Electrostatics in the presence of spherical dielectric discontinuities
Authors: Linse Per
Published: June 2008

A united description of the electrostatics of an arbitrary number of electrostatic multipoles, each localized in a spherical dielectric cavity, in a dielectric medium is presented. The permanent charges as well as the polarization surface charges are described by multipole expansions in standard format. Expressions of the polarization surface charge density, the electrostatic potential energy, and the electrostatic interaction including the contribution from the polarization surface charge densities are given. Interacting electrostatic multipoles in dielectric spheres immersed in a medium with a higher (lower) relative dielectric permittivity experience a repulsive (attractive) potential term that increases in magnitude at reduced multipole separation, originating from the polarization surface charges appearing at the dielectric interfaces. Simplified expressions applied to monopoles and to two dielectric cavities are provided. Numerical examples involving monopoles and dipoles quantifying the effect of the surface polarization are also included.
Boundary conditions in local electrostatics algorithms
Authors: Levrel L. , Maggs A. C.
Published: June 2008

We study the simulation of charged systems in the presence of general boundary conditions in a local Monte Carlo algorithm based on a constrained electric field. We first show how to implement constant-potential, Dirichlet boundary conditions by introducing extra Monte Carlo moves to the algorithm. Second, we show the interest of the algorithm for studying systems which require anisotropic electrostatic boundary conditions for simulating planar geometries such as membranes.
Influence of Lewis number on the surface density function transport in the thin reaction zone regime for turbulent premixed flames
Authors: Chakraborty Nilanjan , Klein Markus
Published: June 2008

The effects of tangential strain rate and curvature on the surface density function (SDF) and on different terms within the SDF transport equation in the thin reaction zone regime are studied for statistically planar turbulent premixed flames with global Lewis numbers Le=0.8, 1.0, and 1.2 by using three-dimensional direct numerical simulations with simplified chemistry. A positive correlation is observed between the SDF and tangential strain rate, and this is explained in terms of the local statistical behaviors of tangential strain rate and dilatation rate. Curvature is shown to affect the SDF through the curvature response of both tangential strain rate and dilatation rate on a given flame isosurface. The correlation between the curvature and SDF is positive in the Le=0.8 flame and negative in the Le=1.2 flame. The curvature dependence of the SDF is weak in the case of unity Lewis number. Strain rate and curvature are found to have an appreciable effect on different terms of the SDF transport equation. The SDF strain rate term arising from tangential strain rate contribution in all the flames is positively correlated with tangential strain rate as expected and is also negatively correlated with curvature. For the Le=1.0 and 1.2 flames, the SDF propagation term is found to negatively correlate with flame curvature toward the reactant side of the flame and positively toward the product side. By contrast, for the Le=0.8 flame, the SDF propagation term is negatively correlated with curvature throughout the flame brush. The variation of the SDF curvature term with local flame curvature for all the flames is found to be nonlinear due to the additional stretch induced by the tangential diffusion component of the displacement speed. Physical explanations are provided for all of these effects, and the modeling implications are discussed in detail.
Electrostatic turbulence driven by high magnetohydrodynamic activity in Tokamak Chauffage Alfvén Brésilien
Authors: Guimarães-Filho Zwinglio O. , Caldas Iberê L. , Viana Ricardo L. , Heller Maria Vittoria A. P. , Nascimento Ivan C. , Kuznetsov Yuri K. , Bengtson Roger D.
Published: June 2008

In Tokamak Chauffage Alfvén Brésilien [R. M. O. Galvão et al., Plasma Phys. Controlled Fusion 43, 1181 (2001)], high magnetohydrodynamic (MHD) activity may appear spontaneously or during discharges with a voltage biased electrode inserted at the plasma edge. The turbulent electrostatic fluctuations, measured by Langmuir probes, are modulated by Mirnov oscillations presenting a dominant peak with a common frequency around 10kHz. We report the occurrence of phase locking of the turbulent potential fluctuations driven by MHD activity at this frequency. Using wavelet cross-spectral analysis, we characterized the phase and frequency synchronization in the plasma edge region. We introduced an order parameter to characterize the radial dependence of the phase-locking intensity.
Dust ion-acoustic solitary waves in a dusty plasma with positive and negative ions
Authors: Sayed F. , Haider M. M. , Mamun A. A. , Shukla P. K. , Eliasson B. , Adhikary N.
Published: June 2008

Properties of small but finite amplitude dust ion-acoustic (DIA) solitary waves in a dusty plasma composed of inertialess electrons, positive and negative inertial ions, and immobile negative/positive charged dust grains are investigated. By using the multifluid dusty plasma model, the Kortweg–de Vries equation and energy integral for small and large amplitude solitary pulses, are derived. It is found that the presence of the negative ions modifies the properties of the solitary DIA waves, and provides the possibility of positive and negative solitary potential structures to coexist. The present results may be useful for understanding the salient features of localized DIA excitations that may appear in data from forthcoming laboratory experiments and space observations.
Issues with measurements of the convective velocity of large-scale structures in the compressible shear layer of a free jet
Authors: Thurow Brian S. , Jiang Naibo , Kim Jin-Hwa , Lempert Walter , Samimy Mo
Published: June 2008

Experiments were conducted to measure convective velocity of large-scale structures in the shear layer of a Mach 2.0 free jet with a convective Mach number of 0.87 and Reynolds number based on a nozzle diameter of 2.6×106. Real-time flow visualization and planar Doppler velocimetry (PDV) measurements along with space-time correlation were used. The results reveal that regardless of the measurement technique employed, whether qualitative flow visualization or quantitative PDV, the method of seeding can have a significant effect on the ability to accurately identify, track, and measure convective velocity of large-scale structures. This is apparent by the relatively large spread in convective velocity results obtained in the same jet by using various methods of seeding and qualitative and quantitative visualization. Convective velocity measurements made under the best seeding conditions available with PDV indicate a convective velocity of structures that is close to the value predicted by theory up to the convective Mach number of 0.87 used in the current work. This is in contrast to previously reported convective velocity measurements (including those of the present authors) that indicated a deviation from the theoretically predicted value but were based on measurements made under less than ideal seeding conditions.