bluuebunny/crossref_metadata_2025 huggingface dataset:
Translation Regulation and Proteasome Mediated Degradation Cooperate to Keep Stem‐Loop Binding Protein Low in G1‐Phase
Authors: Djakbarova Umidahan , Marzluff William F. , Köseoğlu M. Murat
Published: October 2013

Histone mRNA levels are cell cycle regulated, and the major regulatory steps are at the posttranscriptional level. A major regulatory mechanism is S‐phase restriction of Stem‐loop binding protein (SLBP) which binds to the 3′ end of histone mRNA and participates in multiple steps of histone mRNA metabolism, including 3′ end processing, translation and regulation of mRNA stability. SLBP expression is cell cycle regulated without significant change in its mRNA level. SLBP expression is low in G1 until just before S phase where it functions and at the end of S phase SLBP is degraded by proteasome complex depending on phosphorylations on Thr60 and Thr61. Here using synchronized HeLa cells we showed that SLBP production rate is low in early G1 and recovers back to S phase level somewhere between early and mid‐G1. Further, we showed that SLBP is unstable in G1 due to proteasome mediated degradation as a novel mechanism to keep SLBP low in G1. Finally, the S/G2 stable mutant form of SLBP is degraded by proteasome in G1, indicating that indicating that the SLBP degradation in G1 is independent of the previously identified SLBP degradation at S/G2. In conclusion, as a mechanism to limit histone production to S phase, SLBP is kept low in G1 phase due to cooperative action of translation regulation and proteasome mediated degradation which is independent of previously known S/G2 degradation. J. Cell. Biochem. 115: 523–530, 2014. © 2013 Wiley Periodicals, Inc.
miRNA27a Is a Biomarker for Predicting Chemosensitivity and Prognosis in Metastatic or Recurrent Gastric Cancer
Authors: Huang Dingzhi , Wang Haiyan , Liu Rui , Li Hongli , Ge Shaohua , Bai Ming , Deng Ting , Yao Guangyu , Ba Yi
Published: October 2013

We previously identified five miRNAs (miR‐1, miR‐20a, miR‐27a, miR‐34a, and miR‐423‐5p) that are up‐regulated in gastric cancer. The goal of this study was to investigate the value of these miRNAs as potential biomarkers for predicting chemosensitivity and prognosis in metastatic or recurrent gastric cancer patients who received first‐line chemotherapy. A total of 82 patients with metastatic or recurrent GC receiving first‐line chemotherapy were included in our study. The expression levels of the five miRNAs were evaluated using hydrolysis probe‐based stem‐loop quantitative reverse transcription polymerase chain reaction (qRT‐PCR) in individual samples before first‐line chemotherapy. Patients receiving first‐line chemotherapy with fluoropyrimidine combined with oxaliplatin or paclitaxel were chosen for the chemosensitivity analysis. The relationships between expression of the five‐miRNAs and clinicopathological parameters, response to chemotherapy and prognosis were analyzed statistically. Patients with higher miRNA1 expression levels tended to have a higher rate of liver metastasis, and higher miRNA34a expression levels occurred more frequently in males (P = 0.022). The expression of the remaining three miRNAs showed no obvious relationship to any of the clinicopathological features. The partial response rates of the patients with high miRNA1 expression and low miRNA1 expression were 11.1% and 23.1%, respectively (P = 0.048). Similar results were observed for miRNA27a (the partial response rate was 7.7% vs. 25.9%, P = 0.018). Patients with up‐regulated miRNA27a expression had a significantly worse overall survival (OS) than patients with lower miRNA27a expression (P = 0.024). In patients with MRGC, miRNA27a is a potential biomarker for predicting resistance to fluoropyrimidine‐based chemotherapy and a novel prognostic marker for gastric cancer. J. Cell. Biochem. 115: 549–556, 2014. © 2013 Wiley Periodicals, Inc.
An extensible interface for QM/MM molecular dynamics simulations with AMBER
Authors: Götz Andreas W. , Clark Matthew A. , Walker Ross C.
Published: October 2013

We present an extensible interface between the AMBER molecular dynamics (MD) software package and electronic structure software packages for quantum mechanical (QM) and mixed QM and classical molecular mechanical (MM) MD simulations within both mechanical and electronic embedding schemes. With this interface, ab initio wave function theory and density functional theory methods, as available in the supported electronic structure software packages, become available for QM/MM MD simulations with AMBER. The interface has been written in a modular fashion that allows straight forward extensions to support additional QM software packages and can easily be ported to other MD software. Data exchange between the MD and QM software is implemented by means of files and system calls or the message passing interface standard. Based on extensive tests, default settings for the supported QM packages are provided such that energy is conserved for typical QM/MM MD simulations in the microcanonical ensemble. Results for the free energy of binding of calcium ions to aspartate in aqueous solution comparing semiempirical and density functional Hamiltonians are shown to demonstrate features of this interface. © 2013 Wiley Periodicals, Inc.
The RTAM electronic bibliography, version 17.0, on relativistic theory of atoms and molecules
Authors: Pyykkö Pekka
Published: October 2013

The RTAM bibliography is freely available at rtam.csc.fi and the Version 17.0 of August 22, 2013 now contains 16,566 items from the year 1916–2013. “Production works” were systematically covered until 1999. Since the year 2000, mainly methodological papers were included. The methods and principles behind RTAM are described. © 2013 Wiley Periodicals, Inc.
Coupled‐cluster reaction barriers of : An application of the coupled‐cluster//Kohn–Sham density functional theory model chemistry
Authors: Viegas Luís P. , Varandas António J. C.
Published: October 2013

In this work, we report a theoretical investigation concerning the use of the popular coupled‐cluster//Kohn‐Sham density functional theory (CC//KS‐DFT) model chemistry, here applied to study the entrance channel of the reaction, namely by comparing CC//KS‐DFT calculations with KS‐DFT, MRPT2//CASSCF, and CC//CASSCF results from our previous investigations. This was done by performing single point energy calculations employing several coupled cluster methods and using KS‐DFT geometries optimized with six different functionals, while conducting a detailed analysis of the barrier heights and topological features of the curves and surfaces here obtained. The quality of this model chemistry is critically discussed in the context of the title reaction and also in a wider context. © 2013 Wiley Periodicals, Inc.
Review on the Recent Progress in Low Band Gap Conjugated Polymers for Bulk Hetero‐junction Polymer Solar Cells
Authors: Jhuo Hong‐Jyun , Yeh Po‐Nan , Liao Sih‐Hao , Li Yi‐Lun , Cheng Yu‐Shan , Chen Show‐An
Published: October 2013

In the past few years, tremendous progress in power conversion efficiency (PCE) of polymer solar cell (PSC) via design of novel conjugated polymers has been made. In order to further promote PCE, an efficient way is to narrow down optical band gap of the polymers. This review focuses on low band gap polymers based on Donor—Acceptor (D—A) strategy and quinoid form structure. At first, we introduce the requirements for polymers, such as tuning of energy levels. Second, we introduce the importance of main chain, side chain and substituents, which affect the optical and electrical properties, intra/intermolecular interactions, and charge mobility. We survey the important donor and acceptor units and discuss the guidelines for developing highly efficient conjugated polymers. We classify the polymers into several categories in accordance with the structures of acceptor units: Benzodiathiazole (BT), Thienopyrrolodione (TPD) and Diketopyrrolopyrrole (DPP), to which the copolymers with various donors have promissing efficiency. Low band gap polymers based on the quinoid structure, thienothiophene (TT), having promising efficiency are also included.
Impact of S100A8/A9 Expression on Prostate Cancer Progression In Vitro and In Vivo
Authors: Grebhardt Sina , Müller‐Decker Karin , Bestvater Felix , Hershfinkel Michal , Mayer Doris
Published: October 2013

The proinflammatory S100A8/A9 proteins, which are expressed in myeloid cells under physiological conditions, are strongly expressed in human prostate cancer epithelial cells. Their role in the tumor cells and in tumor progression is largely unclear. We established a prostate cancer epithelial cell line (PC‐3 TO‐A8/A9) expressing S100A8 and S100A9 simultaneously under doxycycline control, to study the role of S100A8/A9 on tumor growth and infiltration of immune cells in subcutaneous xenografts in male NMRI nu/nu mice. Colonization of distant organs was studied after intracardial injection of the tumor cells in male NOD/SCID mice. PC‐3 TO‐A8/A9 cells grown in vitro and subcutaneous xenografts in mice not treated with doxycycline expressed high levels of S100A8/A9 mRNA and protein, whereas doxycycline treatment suppressed S100A8/A9 expression. S100A8/A9 expression did not significantly alter growth rate and invasion of the subcutaneous tumors into surrounding tissues. However, S100A8/A9 expression caused increased infiltration of immune cells, especially neutrophils. In intracardially injected mice sporadic tumor settlement was observed in muscle and lymph nodes. Colonies of tumor cells and micro‐metastases were observed in the lung of 64.3% (9 out of 14) of mice not treated with doxycycline and in 33.3% (5 out of 15) of mice treated with doxycycline. Our data demonstrate for the first time that S100A8/A9 expression in epithelial cancer cells causes enhanced infiltration of immune cells, especially neutrophils, and stimulates settlement of the cancer cells in the lung. J. Cell. Physiol. 229: 661–671, 2014. © 2013 Wiley Periodicals, Inc.
A drug and disease model for lixisenatide, a GLP‐1 receptor agonist in type 2 diabetes
Authors: Wilkins Justin J. , Dubar Michel , Sébastien Bernard , Laveille Christian
Published: October 2013

Incretin hormone analogs such as glucagon‐like peptide‐1 (GLP‐1) receptor agonists have emerged as promising new options for the treatment of type 2 diabetes mellitus (T2DM), targeting several of its pathophysiological traits, including reduced insulin sensitivity, inadequate insulin secretion, and loss of β‐cell mass (BCM). This article describes the semi‐mechanistic modeling of lixisenatide dose‐response over time using fasting plasma glucose (FPG), fasting serum insulin (FSI) and glycated hemoglobin (HbA1c) data from two Phase II and four Phase III clinical trials, for a total of 2470 T2DM patients. Previously published models for FPG, FSI, and BCM as well as HbA1c were adapted and expanded to describe the available data. The model incorporated aspects describing disease progression, standard‐of‐care, FPG‐dependent and ‐independent HbA1c synthesis, and covariate effects of body size, race, and sex. The final model described lixisenatide effects on β‐cell responsiveness, insulin sensitivity and FPG‐independent HbA1c synthesis, was able to describe the observed FPG, FSI, and HbA1c data accurately, and was successful in predicting data from an unseen Phase III clinical study.
Pharmacokinetics of the novel dual endothelin receptor antagonist macitentan in subjects with hepatic or renal impairment
Authors: Sidharta Patricia N. , Lindegger Nicolas , Ulč Ivan , Dingemanse Jasper
Published: October 2013

Macitentan is under development for the treatment of pulmonary arterial hypertension (PAH). Patients with PAH may suffer from comorbidities such as renal or hepatic impairment. Two prospective, single‐center, open‐label studies evaluated the pharmacokinetics of macitentan and its metabolites (pharmacologically active ACT‐132577 and inactive ACT‐373898) in healthy subjects and in subjects with mild, moderate, and severe hepatic impairment or severe renal function impairment (SRFI). After administering a single oral dose of 10 mg macitentan the pharmacokinetic parameters including area under the curve from zero to infinity (AUC∞) were derived from plasma concentration–time profiles. Exposure to macitentan and ACT‐132577 was lower in hepatically impaired versus healthy subjects, with no correlation with the degree of hepatic impairment. Exposure to ACT‐373898 was lower in subjects with moderate hepatic impairment only. Plasma concentration–time profiles for macitentan and ACT‐132577 (active) were similar in healthy subjects and subjects with SRFI. AUC∞ of ACT‐373898 (inactive) was 7.3‐fold higher in subjects with SRFI versus healthy subjects. No safety concerns were raised in either study. Based on these observations, pharmacokinetic alterations of macitentan due to hepatic or renal function impairment are not considered clinically relevant and no dose adjustment is necessary in these patients.
A multiple ascending dose study of CSL112, an infused formulation of ApoA‐I
Authors: Easton Rachael , Gille Andreas , D'Andrea Denise , Davis Roslyn , Wright Samuel D. , Shear Charles
Published: October 2013

CSL112 is apoA‐I purified from human plasma and reconstituted with phosphatidylcholine (PC) to form high‐density lipoprotein (HDL)‐particles suitable for infusion. CSL112 is in development for the potential treatment of acute coronary syndromes (ACS) by optimizing cholesterol efflux. This study assesses the pharmacokinetics (PK), safety and tolerability of CSL112. Repeat doses of CSL112 or placebo were administered intravenously once‐ (3.4 g or 6.8 g) or twice‐weekly (3.4 g) to healthy subjects in a placebo‐controlled, randomized (3 CSL112: 1 placebo), ascending‐dose study (NCT01281774). Twenty‐seven subjects received CSL112 and nine received placebo. Study endpoints included plasma apoA‐I and PC concentrations and specific PK parameters. CSL112 infusions immediately produced robust increases in apoA‐I concentration in a dose‐proportional manner, reaching levels higher than observed with currently available or investigational HDL products. After infusion of CSL112, apoA‐I levels remained above baseline for approximately 3 days. Multiple infusions of CSL112 were safe and well tolerated with no evidence of major organ toxicity or immunogenicity. CSL112 may provide a novel option to rapidly transport cholesterol from atherosclerotic plaque to the liver and reduce early recurrent events following ACS. The data presented here support continued clinical development of CSL112 in patient populations.
On‐line monitoring of a BNR process using in situ ammonium and nitrate probes and biomass nitrification‐denitrification rates in an intermittently aerated and pulse fed bioreactor
Authors: Melidis Paraschos , Ntougias Spyridon , Sertis Christos
Published: October 2013

BACKGROUND

The need to monitor and optimize biological nitrogen removal (BNR) processes has led to the use of on‐line instrumentation. In situ located sensors can monitor in a real‐time mode the dynamics of microbial processes, providing the opportunity to understand and optimize process performance.

RESULTS

A nitrification–denitrification process was monitored on‐line for the first time in an intermittently aerated and pulse fed activated sludge system using in situ located sensors for ammonia and nitrate. Pulse feeding created a reduced C/N ratio gradient across the anoxic phase, resulting in complete denitrification within a period of 20 min. Two denitrification rates were determined, corresponding to nitrate reduction during utilization of the readily biodegradable (0.110–0.246 g g‐1 d‐1) and the slowly (particulate) biodegradable (0.032–0.041 g g‐1 d‐1) COD, respectively. Despite the fact that the initial C/N ratio at both Food/Microorganism ratio (F/M) 0.20 and 0.28 was decreased from 4.8 to 1.8 at the end of the anoxic phase, the C/N ratio decrease was twice as fast at the higher F/M ratio.

CONCLUSION

Pulse‐feeding resulted in higher C/N ratios at the beginning of the anoxic phase, creating a reduced C/N ratio gradient during the denitrification period. Organic load was mostly consumed during the anoxic phase, resulting in high nitrification efficiency, low oxygen requirement and saving energy. © 2013 Society of Chemical Industry
Adsorption of phenol and chlorophenols onto granular activated carbon and their desorption by supercritical CO2
Authors: Carmona Manuel , Garcia M Teresa , Carnicer Ángel , Madrid Mercedes , Rodríguez Juan Francisco
Published: October 2013

BACKGROUND

The adsorption and desorption of phenol, 2‐chlorophenol (2‐CPh), 4‐chlorophenol (4‐CPh) and 2,4‐dichlorophenol (2,4‐DCPh) were carried out using granular activated carbon (GAC) as adsorbent and supercritical CO2 as regenerant. Adsorption studies at three different temperatures were fitted by using two thermodynamic adsorption models, Langmuir and Toth. The GAC regeneration by CO2 at four different pressures and two temperatures was studied and the design basic parameters were found.

RESULTS

The Toth model fitted the experimental data better and thermodynamic properties indicated that this adsorption process was spontaneous, feasible and exothermic. Values of standard enthalpy lower than 40 kJ mol‐1 confirmed that adsorption processes were carried out by physical adsorption. It was also observed that the higher the pressure the higher the regeneration efficiency due to the increase in solvent density.

CONCLUSION

GAC presented high selectivity for these substituted phenols and the order of adsorption was 2,4‐DCPh > 4‐CPh > 2CPh > phenol. Supercritical technology was able to regenerate the exhausted GAC, achieving yields comparable with those exhibited by traditional technologies but avoiding additional separation processes. The effective diffusivities of phenols followed the order phenol > 2‐CPh≅4‐CPh > 2,4‐DCPh. © 2013 Society of Chemical Industry
One‐pot synthesis of methyl n‐phenyl carbamate from aniline, carbon dioxide and methanol
Authors: Zhao Bin , Yao Sujie , An Hualiang , Zhao Xinqiang , Wang Yanji
Published: October 2013

BACKGROUND

Methyl N‐phenyl carbamate (MPC) is an intermediate for the manufacture of methylene diphenyl diisocyanate (MDI) by a non‐phosgene route. The synthesis of MPC from aniline, carbon dioxide and methanol can transform the greenhouse gas carbon dioxide into value‐added product, MPC.

RESULTS

Bicyclic amidine (DBU)–acetonitrile was found to be an excellent catalyst–solvent combination for MPC synthesis. Under the reaction conditions of initial pressure of carbon dioxide 1 MPa, reaction time 5 h, reaction temperature 180°C, volumetric ratio of methanol/aniline 1:4, volumetric ratio of acetonitrile/aniline 1:1, and mass percentage of DBU 5.6%, the conversion of aniline was 7.1% and the selectivity of MPC was 25.3%. A plausible catalytic reaction mechanism was proposed. The results of alkyl N‐phenyl carbamate (APC) synthesis from aniline, carbon dioxide and alcohol (methanol, ethanol, propanol or butanol) showed that the conversion of aniline and the selectivity of the corresponding APC decreased significantly with increase of the stereo hindrance on the alcohol substrate.

CONCLUSION

The reaction of aniline, carbon dioxide and alcohol to APC, especially MPC, can be achieved even though stereo hindrance on the alcohol substrate limits the reaction. © 2013 Society of Chemical Industry
Homogeneous photo‐Fenton mineralization of the antibiotic sulfamethazine in water under UV‐A, visible and solar irradiation
Authors: Kitsiou Vassiliki , Antoniadis Apostolos , Mantzavinos Dionissios , Poulios Ioannis
Published: October 2013

BACKGROUND

The presence of pharmaceutical residues in the aquatic environment is an emerging issue due to their uncontrolled release and accumulation in the environment that may affect living organisms, ecosystems and public health. As a result, efforts are being made to develop methods to inactivate or eliminate this class of substance in the environment.

RESULTS

The homogeneous photocatalytic degradation of sulfamethazine (SMT), a sulfanilamide drug, has been investigated in aqueous solutions using artificial and solar illumination. The effects of initial concentration of H2O2 (10–400 mg L‐1), Fe3+ (3.5–28 mg L‐1), SMT (10–40 mg L‐1), as well as temperature (280–323 K) on mineralization rates were evaluated in a bench‐scale Pyrex reactor for the photo‐Fenton/UV‐A and photo‐Fenton/Vis processes. SMT degradation was accompanied by the release of inorganic nitrogen and sulphate ions. Experiments under natural sunlight conditions were performed in a pilot‐scale, fountain reactor at light intensities between 0.49 and 2.83 mW cm‐2.

CONCLUSIONS

An increase in the level of the parameters had a positive effect, with photo‐Fenton/UV‐A (at 0.94 × 10−4 einstein L−1 min−1 light flux provided by a 9 W lamp at 366 nm maximum response) being more effective than photo‐Fenton/Vis (at 0.88 × 10−4 einstein L−1 min−1 also provided by a 9 W lamp at 440 nm maximum response). Illumination for 120 min in the case of the pilot‐scale reactor at 2 mW cm‐2 intensity led to more than 70% mineralization of 20 mg L‐1 SMT, thus showing that process scale‐up is feasible. © 2013 Society of Chemical Industry
Information: Theory, brain, and behavior
Authors: Jensen Greg , Ward Ryan D. , Balsam Peter D.
Published: October 2013

In the 65 years since its formal specification, information theory has become an established statistical paradigm, providing powerful tools for quantifying probabilistic relationships. Behavior analysis has begun to adopt these tools as a novel means of measuring the interrelations between behavior, stimuli, and contingent outcomes. This approach holds great promise for making more precise determinations about the causes of behavior and the forms in which conditioning may be encoded by organisms. In addition to providing an introduction to the basics of information theory, we review some of the ways that information theory has informed the studies of Pavlovian conditioning, operant conditioning, and behavioral neuroscience. In addition to enriching each of these empirical domains, information theory has the potential to act as a common statistical framework by which results from different domains may be integrated, compared, and ultimately unified.
Attention and psychophysics in the development of stimulus control
Authors: Hutsell Blake A. , Jacobs Eric A.
Published: October 2013

Rats responded in a six‐stimulus, two‐response temporal classification procedure. A successive‐reversal design was used in which the relationship between stimulus class (short vs. long) and correct comparison location (left or right) reversed every 15 sessions. After several reversals, the relative probability of reinforcement for each correct classification was manipulated across subsequent reversals. In each condition, the asymptotic level of preference for the comparison location (response bias) correlated with the greater probability of reinforcement was demonstrated in the first session following a reversal, whereas discrimination accuracy took several more sessions to return to asymptotic levels. A modified version of the attending‐augmented Davison‐Nevin‐Alsop (Davison & Nevin, 1999) model offered by Nevin, Davison, & Shahan (2005) provided an accurate description of the reacquisition data. The comparison‐attending parameters remained high and relatively constant following reversals, while sample‐attending parameters initially decreased following reversals, and then increased gradually across sessions. These findings support key assumptions of the attending model; sample‐ and comparison‐attending are independent processes that modulate the expression of discriminative control exerted by those stimuli over operant behavior.
Gene‐based therapies of neuromuscular disorders: an update and the pivotal role of patient organizations in their discovery and implementation
Authors: Braun Serge
Published: October 2013

This review updates the state‐of‐the art accomplishments of the multifaceted gene‐based therapies, which include DNA or RNA as either therapeutic tools or targets for the treatment of neuromuscular diseases. It also provides insights into the key role that patient organizations have played in research and development; in particular, by addressing bottlenecks and generating boundary conditions that have contributed to scientific breakthroughs, and the effectiveness of innovation processes. Several gene therapy methods have reached the clinical stage and are now addressing both specific and classical issues related to this novel technology. Not ready yet for clinical application, genome editing is at its infancy. More rapidly progressing, RNA‐based therapeutics, and especially exon skipping, exon inclusion and stop codon readthrough strategies, are about to move to the market. Most importantly, patients were at the forefront of this discovery process, from basic knowledge to innovation and translational research in a rapidly growing field of unmet medical needs. In recent years, Duchenne muscular dystrophy was the fertile ground for new therapeutic concepts that have been extended to other neuromuscular disorders, such as spinal muscular atrophy, myotonic dystrophies or fascioscapulohumeral dystrophy. In line with their longstanding policy, patient organizations will keep working in a proactive manner to bring together all stakeholders with a view to working out truly therapeutic solutions over a long‐term perspective. Copyright © 2013 John Wiley & Sons, Ltd.
Global empirical model of TEC response to geomagnetic activity
Authors: Mukhtarov P. , Andonov B. , Pancheva D.
Published: October 2013

A global total electron content (TEC) model response to geomagnetic activity described by the Kp index is built by using the Center for Orbit Determination of Europe (CODE) TEC data for a full 13 years, January 1999 to December 2011. The model describes the most probable spatial distribution and temporal variability of the geomagnetically forced TEC anomalies assuming that these anomalies at a given modified dip latitude depend mainly on the Kp index, local time (LT), and longitude. The geomagnetic anomalies are expressed by the relative deviation of TEC from its 15 day median and are denoted as rTEC. The rTEC response to the geomagnetic activity is presented by a sum of two responses with different time delay constants and different signs of the cross‐correlation function. It has been found that the mean dependence of rTEC on Kp index can be expressed by a cubic function. The LT dependence of rTEC is described by Fourier time series which includes the contribution of four diurnal components with periods 24, 12, 8, and 6 h. The rTEC dependence on longitude is presented by Fourier series which includes the contribution of zonal waves with zonal wave numbers up to 6. In order to demonstrate how the model is able to reproduce the rTEC response to geomagnetic activity, three geomagnetic storms at different seasons and solar activity conditions are presented. The model residuals clearly reveal two types of the model deviation from the data: some underestimation of the largest TEC response to the geomagnetic activity and randomly distributed errors which are the data noise or anomalies generated by other sources. The presented TEC model fits to the CODE TEC input data with small negative bias of −0.204, root mean squares error RMSE = 4.592, and standard deviation error STDE = 4.588. The model offers TEC maps which depend on geographic coordinates (5° × 5° in latitude and longitude) and universal time (UT) at given geomagnetic activity and day of the year. It could be used for both science and possible service (nowcasting and short‐term prediction); for the latter, a detailed validation of the model at different geophysical conditions has to be performed in order to clarify the model predicting quality.
Empirical modeling of plasma sheet pressure and three‐dimensional force‐balanced magnetospheric magnetic field structure: 1. Observation
Authors: Wang Chih‐Ping , Yue Chao , Zaharia Sorin , Xing Xiaoyan , Lyons Larry , Angelopoulos Vassilis , Nagai Tsugunobu , Lui Tony
Published: October 2013

A three‐dimensional (3‐D) magnetic field configuration in force balance with a realistic plasma pressure distribution can provide more accurate evaluation of the role of magnetic field on plasma sheet dynamics and M‐I coupling. We used Geotail and Time History of Events and Macroscale Interactions During Substorms (THEMIS) data to establish an empirical model for nightside equatorial isotropic plasma pressure to r = 30 RE for Kp = 0–5 and for solar wind dynamic pressure (PSW) = 1.5 and 3 nPa. The model pressure is used in the companion paper for modeling a 3‐D force‐balanced pressure and magnetic field equilibrium. Larger convection during higher Kp drives the plasma sheet further earthward, resulting in larger increase of pressure and pressure gradient at smaller radial distance. On the other hand, magnetosphere compression by increasing PSW enhances pressure and pressure gradient mainly in the tail plasma sheet. While both pressure and radial gradients are enhanced with increasing Kp or PSW, there is no significant azimuthal pressure variation statistically under all Kp and PSW conditions. The empirical pressures well reproduce these statistical profiles with very high correlation coefficients. Additionally, comparisons with pressure gradients computed using two simultaneous measurements from two THEMIS spacecraft show reasonable agreement. Furthermore, our model provides more accurate pressure gradients than previous empirical models. The model magnetic field distributions obtained in the companion paper from requiring force balance with these empirical pressure profiles are also found to be consistent with the magnetic field observations, indicating that our equilibria well represent realistic 3‐D pressure and magnetic field configurations.
Specifying the equatorial ionosphere using CINDI on C/NOFS, COSMIC, and data interpolating empirical orthogonal functions
Authors: Stoneback R. A. , Malakar N. K. , Lary D. J. , Heelis R. A.
Published: October 2013

Data Interpolating Empirical Orthogonal Functions (DINEOFs) are a data‐based method for determining a few orthogonal basis functions that optimally reproduce a given data set. This technique is applied to meridional drift measurements performed by the Coupled Ion Neutral Dynamics Investigation (CINDI) onboard the Communication/Navigation Outage Forecasting System (C/NOFS) as well as electron density profiles derived from GPS Radio Occulations (RO) performed by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). The low densities of the equatorial ionosphere spanning 2009–2010 restricted quality drift measurements by CINDI to altitudes near perigee, limiting the local time coverage of measurements. Full local time descriptions may be obtained as perigee moves through all local times though this requires a minimum 67 day season. To increase the data coverage of the ionosphere, CINDI data are supplemented with COSMIC GPS RO data. DINEOFs are applied to median meridional drift measurements as well as COSMIC measurements spanning 2009–2010 and are used to make a best estimate of the equatorial ionosphere at locations not observed. The scattered distribution of COSMIC profiles as well as the physical relationship between meridional ion drifts and the distribution of density with altitude improves the quality of the reconstructions compared to using CINDI alone. The DINEOF reconstructions demonstrate that the annual anomaly of reduced ionospheric densities in June compared to December measured by COSMIC is coincident with a change in the meridional ion drifts at the geomagnetic equator measured by CINDI.
A reexamination of latitudinal limits of substorm‐produced energetic electron precipitation
Authors: Cresswell‐Moorcock Kathy , Rodger Craig J. , Kero Antti , Collier Andrew B. , Clilverd Mark A. , Häggström Ingemar , Pitkänen Timo
Published: October 2013

The primary sources of energetic electron precipitation (EEP) which affect altitudes <100 km (>30 keV) are expected to be from the radiation belts and during substorms. EEP from the radiation belts should be restricted to locations between L = 1.5 and 8, while substorm‐produced EEP is expected to range from L = 4 to 9.5 during quiet geomagnetic conditions. Therefore, one would not expect any significant D region impact due to electron precipitation at geomagnetic latitudes beyond about L = 10. In this study we report on large unexpectedly high‐latitude D region ionization enhancements, detected by an incoherent scatter radar at L ≈ 16, which appear to be caused by electron precipitation from substorms. We go on to reexamine the latitudinal limits of substorm‐produced EEP using data from multiple low‐Earth orbiting spacecraft, and demonstrate that the precipitation stretches many hundreds of kilometers poleward of the previously suggested limits. We find that a typical substorm will produce significant EEP over the International Geomagnetic Reference Field L shell range L = 4.6 ± 0.2–14.5 ± 1.2, peaking at L = 6–7. However, there is significant variability from event to event; in contrast to the median case, the strongest 25% of substorms have significant EEP in the range spanning L = 4.1 ± 0.1–20.7 ± 2.2, while the weakest 25% of substorms have significant EEP in the range spanning L = 5.5 ± 0.1–10.1 ± 0.7. We also examine the occurrence probability of very large substorms, focusing on those events which appear to be able to disable geostationary satellites when they are located near midnight magnetic local time. On average, these large substorms occur approximately one to six times per year, a significant rate, given the potential impact on satellites.
Multiple bidirectional EMIC waves observed by Cluster at middle magnetic latitudes in the dayside magnetosphere
Authors: Allen R. C. , Zhang J. ‐C. , Kistler L. M. , Spence H. E. , Lin R. ‐L. , Dunlop M. W. , André M.
Published: October 2013

It is well accepted that the propagation of electromagnetic ion cyclotron (EMIC) waves are bidirectional near their source regions and unidirectional when away from these regions. The generally believed source region for EMIC waves is around the magnetic equatorial plane. Here we describe a series of EMIC waves in the Pc1 (0.2–5 Hz) frequency band above the local He+ cyclotron frequency observed in situ by all four Cluster spacecraft on 9 April 2005 at midmagnetic latitudes (MLAT = ~33°–49°) with L = 10.7–11.5 on the dayside (MLT = 10.3–10.4). A Poynting vector spectrum shows that the wave packets consist of multiple groups of packets propagating bidirectionally, rather than unidirectionally, away from the equator, while the local plasma conditions indicate that the spacecraft are entering into a region sufficient for local wave excitation. One possible interpretation is that, while part of the observed waves are inside their source region, the others are either close enough to the source region, or mixed with the wave packets from multiple source regions at different latitudes.
Cyclic reformation of a quasi‐parallel bow shock at Mercury: MESSENGER observations
Authors: Sundberg Torbjörn , Boardsen Scott A. , Slavin James A. , Uritsky Vadim M. , Anderson Brian J. , Korth Haje , Gershman Daniel J. , Raines Jim M. , Zurbuchen Thomas H. , Solomon Sean C.
Published: October 2013

We here document with magnetic field observations a passage of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft through Mercury's magnetosphere under conditions of a quasi‐parallel bow shock, i.e., when the direction of the upstream interplanetary magnetic field was within 45° of the bow shock normal. The spacecraft's fast transition of the magnetosheath and the steady solar wind conditions during the period analyzed allow both spatial and temporal properties of the shock crossing to be investigated. The observations show that the shock reformation process can be nearly periodic under stable solar wind conditions. Throughout the 25‐min‐long observation period, the pulsation duration deviated by at most ~10% from the average 10 s period measured. This quasiperiodicity allows us to study all aspects of the shock reconfiguration, including ultra‐low‐frequency waves in the upstream region and large‐amplitude magnetic structures observed in the vicinity of the magnetosheath‐solar wind transition region and inside the magnetosheath. We also show that bow shock reformation can be a substantial source of wave activity in the magnetosphere, on this occasion having given rise to oscillations in the magnetic field with peak‐to‐peak amplitudes of 40–50 nT over large parts of the dayside magnetosphere. The clean and cyclic behavior observed throughout the magnetosphere, the magnetosheath, and the upstream region indicates that the subsolar region was primarily influenced by a cyclic reformation of the shock front, rather than by a spatial and temporal patchwork of short large‐amplitude magnetic structures, as is generally the case at the terrestrial bow shock under quasi‐parallel conditions.
Simultaneous traveling convection vortex events and Pc1 wave bursts at cusp latitudes observed in Arctic Canada and Svalbard
Authors: Posch J. L. , Engebretson M. J. , Witte A. J. , Murr D. L. , Lessard M. R. , Johnsen M. G. , Singer H. J. , Hartinger M. D.
Published: October 2013

Traveling convection vortices (TCVs), which appear in ground magnetometer records at near‐cusp latitudes as solitary ~5 mHz pulses, are a signature of dynamical processes in the ion foreshock upstream of the Earth's bow shock that can stimulate transient compressions of the dayside magnetosphere. These compressions can also increase the growth rate of electromagnetic ion cyclotron (EMIC) waves, which appear in ground records at these same latitudes as bursts of Pc1 pulsations. In this study we have identified TCVs and simultaneous Pc1 burst events in two regions, Eastern Arctic Canada and Svalbard, using a combination of fluxgate magnetometers and search coil magnetometers in each region. By looking for the presence of TCVs and Pc1 bursts in two different sequences, we have found that the distribution of Pc1 bursts was more tightly clustered near local noon than that of TCV events, that neither TCVs nor Pc1 bursts were always associated with the other, and even when they occurred simultaneously their amplitudes showed little correlation. Magnetometer data from GOES‐12 were also used to characterize the strength of the magnetic compressions at geosynchronous orbit near the magnetic equator. Compressions > 2 nT at GOES‐12 occurred during 57% of the Canadian TCV events, but during ~85% of the simultaneous TCV/Pc1 burst events. There was again little evident correlation between TCV and GOES‐12 compression amplitudes. We have also documented unusually low EMIC wave activity during this deep solar minimum interval, and we attribute the low occurrence percentage of combined events in this study to this minimum.
A comparison between resonant and nonresonant heating at EISCAT
Authors: Bryers C. J. , Kosch M. J. , Senior A. , Rietveld M. T. , Singer W.
Published: October 2013

We compare the height‒integrated electron heating rates from O‒ and X‒mode HF pump waves to extract the components due to resonant and nonresonant heating mechanisms in the ionosphere. We present results from a November 2011 campaign in Norway, using the European Incoherent Scatter (EISCAT) heater facility and UHF radar. We show that the theoretical nonresonant, ohmic heating due to the electromagnetic pump wave electric field agrees with observations for X‒mode pumping. For O‒mode pumping, the observed height‒integrated heating rate exceeds the theoretical ohmic electron heating rate by a factor of 2–5, the excess being attributed to resonant heating mechanisms. In addition, a persistent UHF ion‒line enhancement is observed for O‒mode and, more unusually, X‒mode pumping. We attribute the latter to O‒mode leakage in the X‒mode pulse. For O‒mode, we see a descent in altitude of the ion‒line enhancement and show that this is most likely due to ionization from pump‒induced fluxes of suprathermal electrons. We estimate the ionization rate and determine an enhanced electron flux showing that approximately 10–20% of the pump power is transferred to high energy suprathermal electrons.
Megathrust splay faults at the focus of the Prince William Sound asperity, Alaska
Authors: Liberty Lee M. , Finn Shaun P. , Haeussler Peter J. , Pratt Thomas L. , Peterson Andrew
Published: October 2013

High‐resolution sparker and crustal‐scale air gun seismic reflection data, coupled with repeat bathymetric surveys, document a region of repeated coseismic uplift on the portion of the Alaska subduction zone that ruptured in 1964. This area defines the western limit of Prince William Sound. Differencing of vintage and modern bathymetric surveys shows that the region of greatest uplift related to the 1964 Great Alaska earthquake was focused along a series of subparallel faults beneath Prince William Sound and the adjacent Gulf of Alaska shelf. Bathymetric differencing indicates that 12 m of coseismic uplift occurred along two faults that reached the seafloor as submarine terraces on the Cape Cleare bank southwest of Montague Island. Sparker seismic reflection data provide cumulative Holocene slip estimates as high as 9 mm/yr along a series of splay thrust faults within both the inner wedge and transition zone of the accretionary prism. Crustal seismic data show that these megathrust splay faults root separately into the subduction zone décollement. Splay fault divergence from this megathrust correlates with changes in midcrustal seismic velocity and magnetic susceptibility values, best explained by duplexing of the subducted Yakutat terrane rocks above Pacific plate rocks along the trailing edge of the Yakutat terrane. Although each splay fault is capable of independent motion, we conclude that the identified splay faults rupture in a similar pattern during successive megathrust earthquakes and that the region of greatest seismic coupling has remained consistent throughout the Holocene.
Seismic images of the sliver strike‐slip fault and back thrust in the Andaman‐Nicobar region
Authors: Singh Satish C. , Moeremans Raphaele , McArdle Jo , Johansen Kjell
Published: October 2013

The sliver strike‐slip Great Sumatra Fault (GSF) traverses mainland Sumatra from the Sunda Strait in the southeast to Banda Aceh in the northwest, and defines the present day plate boundary between the Sunda Plate in the north and the Burmese Sliver Plate in the south. It has been well studied on mainland Sumatra but poorly north of Banda Aceh in the Andaman Sea. Here we present deep seismic reflection images along the northward extension of the GSF over 700 km until it joins the Andaman Sea Spreading Centre, and we interpret these images in the light of earthquake, gravity, and bathymetry data. We find that the GSF has two strands between Banda Aceh and Nicobar Island: a transpression in the south and a deep narrow active rift system in the north, dotted with volcanoes in the center, suggesting that the volcanic arc is coincident with rifting. Farther north of Nicobar Island, an active strike‐slip fault, the Andaman‐Nicobar Fault, cuts through a rifted deep basin until its intersection with the Andaman Sea Spreading Centre. The volcanic arc lies just east of the rift basin. The western margin of this basin seems to be a rifted continental margin, tilted westward, and flooring the Andaman‐Nicobar fore‐arc basin. The Andaman‐Nicobar fore‐arc basin is bounded in the west by back thrusts similar to the West Andaman and Mentawai faults. The cluster of seismicity after the 2004 great Andaman‐Sumatra earthquake just north of Nicobar Island coincides with the intersection of two strike‐slip fault systems.
Observing coseismic gravity change from the Japan Tohoku‐Oki 2011 earthquake with GOCE gravity gradiometry
Authors: Fuchs Martin J. , Bouman Johannes , Broerse Taco , Visser Pieter , Vermeersen Bert
Published: October 2013

The Japan Tohoku‐Oki earthquake (9.0 Mw) of 11 March 2011 has left signatures in the Earth's gravity field that are detectable by data of the Gravity field Recovery and Climate Experiment (GRACE) mission. Because the European Space Agency's (ESA) satellite gravity mission Gravity field and steady‐state Ocean Circulation Explorer (GOCE)—launched in 2009—aims at high spatial resolution, its measurements could complement the GRACE information on coseismic gravity changes, although time‐variable gravity was not foreseen as goal of the GOCE mission. We modeled the coseismic earthquake geoid signal and converted this signal to vertical gravity gradients at GOCE satellite altitude. We combined the single gradient observations in a novel way reducing the noise level, required to detect the coseismic gravity change, subtracted a global gravity model, and applied tailored outlier detection to the resulting gradient residuals. Furthermore, the measured gradients were along‐track filtered using different gradient bandwidths where in the space domain Gaussian smoothing has been applied. One‐year periods before and after earthquake occurrence have been compared with the modeled gradients. The comparison reveals that the earthquake signal is well above the accuracy of the vertical gravity gradients at orbital height. Moreover, the obtained signal from GOCE shows a 1.3 times higher amplitude compared with the modeled signal. Besides the statistical significance of the obtained signal, it has a high spatial correlation of ~0.7 with the forward modeled signal. We conclude therefore that the coseismic gravity change of the Japan Tohoku‐Oki earthquake left a statistically significant signal in the GOCE measured gravity gradients.
Spatial variations in isostatic compensation mechanisms of the Ninetyeast Ridge and their tectonic significance
Authors: Sreejith K. M. , Krishna K. S.
Published: October 2013

The Ninetyeast Ridge (NER), one of the longest linear volcanic features on the Earth, offers an excellent opportunity of understanding the isostatic response to the interactions of mantle plume with the migrating mid‐ocean ridge. Bathymetry, geoid, and gravity (shipborne and satellite) data along 72 closely spaced transects and 17 overlapping grids on the NER are analyzed and modeled to determine the effective elastic thickness (Te) beneath the entire ridge. The results of 2‐D and 3‐D flexural modeling of the NER show large spatial variations in Te values ranging from 4 to 35 km, suggesting that the ridge was compensated along its length by different isostatic mechanisms. The southern (south of 22°S latitude) and northern (north of 2°N latitude) parts of the NER have Te values of >10 and >23 km, respectively, revealing that the southern part was emplaced on a lithosphere of intermediate strength possibly on flank of the Indian plate, whereas the northern part was emplaced in an intraplate setting. In contrast, in the central part of the NER (between latitudes 22°S and 2°N), highly variable Te values (4–22 km) are estimated. The scattered Te values in the central NER suggest that this part may have evolved due to the occurrence of frequent ridge jumps caused by the interaction of Kerguelen hot spot with rapid northward migration of the Wharton spreading ridge. Residual Mantle Bouguer Anomaly (RMBA) map of the NER and adjacent basins reveals that the entire length of the NER is associated with a significant negative anomaly up to 200 mGal, indicating the presence of thickened crust or less dense mantle beneath the ridge. 3‐D crustal thickness map of the NER, generated by inversion of the RMBA data, shows a thick crust ranging from 15 to 19 km. The present study clearly shows that NER possesses a highly segmented isostatic pattern with the occurrence of subcrustal underplating or subsurface loading.