bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Chemistry of the Strong Organic Electron‐Donor 1,2,4,5‐Tetrakis(tetramethylguanidino)benzene: Electron Transfer in Donor–Acceptor Couples and Binuclear Late Transition Metal Complexes
Authors: Peters Anastasia , Trumm Christine , Reinmuth Matthias , Emeljanenko Dimitri , Kaifer Elisabeth , Himmel Hans‐Jörg
Published: July 2009

In this work we report on some aspects of the chemistry of the organic electron‐donor 1,2,4,5‐tetrakis(tetramethylguanidino)benzene (ttmgb). Reactions with electron acceptors and proton donors as well as late transition metals to give binuclear complexes (including a binuclear CuII complex with antiferromagnetic coupling through the bridging ttmgb ligand) are analysed. These studies shed some light on the electron‐donor/proton‐acceptor and coordination behaviour of this compound.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Does job loss cause ill health?
Authors: Salm Martin
Published: July 2009

This study estimates the effect of job loss on health for near elderly employees based on longitudinal data from the Health and Retirement Study. Previous studies find a strong negative correlation between unemployment and health. To control for possible reverse causality, this study focuses on people who were laid off for an exogenous reason – the closure of their previous employers' business. I find no causal effect of exogenous job loss on various measures of physical and mental health. This suggests that the inferior health of the unemployed compared to the employed could be explained by reverse causality. Copyright © 2009 John Wiley & Sons, Ltd.
Modelling coastal ground‐ and surface‐water interactions using an integrated approach
Authors: Yuan Dekui , Lin Binliang
Published: July 2009

Beach water table fluctuations have an impact on the transport of beach sediments and the exchange of solute and mass between coastal aquifer and nearby water bodies. Details are given of the refinement of a dynamically integrated ground‐ and surface‐water model, and its application to study ground‐ and surface‐water interactions in coastal regions. The depth‐integrated shallow‐water equations are used to represent the surface‐water flow, and the extended Darcy's equation is used to represent the groundwater flow, with a hydrostatic pressure distribution being assumed to apply for both these two types of flows. At the intertidal region, the model has two layers, with the surface‐water layer being located on the top of the groundwater layer. The governing equations for these two types of flows are discretized in a similar manner and they are combined to give one set of linear algebraic equations that can be solved efficiently. The model is used to predict water level distributions across sloping beaches, where the water table in the aquifer may or may not decouple from the free water surface. Five cases are used to test the model for simulating beach water table fluctuations induced by tides, with the model predictions being compared with existing analytical solutions and laboratory and field data published in the literature. The numerical model results show that the integrated model is capable of simulating the combined ground‐ and surface‐water flows in coastal areas. Detailed analysis is undertaken to investigate the capability of the model. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and evaluation of [123I]‐indomethacin derivatives as COX‐2 targeted imaging agents
Authors: Uddin Md. Jashim , Crews Brenda C. , Blobaum Anna L. , Kingsley Philip J. , Ghebreselasie Kebreab , Saleh Sam S. , Clanton Jeffrey A. , Baldwin Ronald M. , Marnett Lawrence J.
Published: July 2009

A novel series of iodinated indomethacin derivatives was synthesized, and evaluated as selective inhibitors of COX‐2. Two candidate compounds N‐(p‐iodobenzyl)‐2‐(1‐(p‐chlorobenzoyl)‐5‐methoxy‐2‐methyl‐1H‐indol‐3‐yl)acetamide (3) and 1‐(p‐iodobenzyl)‐5‐methoxy‐2‐methyl‐3‐indoleacetic acid (9) possessed optimum properties suitable for potential in vivo imaging. Arylstannane precursors for radioiododestannylation were synthesized in 70–85% yield from the iodo compounds by reaction with hexabutylditin and tetrakis(triphenylphosphine)palladium(0) in refluxing dioxane. Radioiododestannylation was conducted by reaction with carrier‐added Na[123I] in the presence of Chloramine‐T in an EtOAc/H2O binary system under acidic conditions (pH 3.5), allowing direct isolation of the labeled products by separation of the organic phase. Radioiodinated products [123I]3 and [123I]9 were recovered in a decay‐corrected radiochemical yield of 86–87% and radiochemical purity of 98–99%. Copyright © 2009 John Wiley & Sons, Ltd.
Single‐shot steady‐state free precession can detect myocardial edema in patients: A feasibility study
Authors: Green Jordin D. , Clarke James R. , Flewitt Jacqueline A. , Friedrich Matthias G.
Published: July 2009

Purpose

To demonstrate the ability of single‐shot, T2/T1 weighted steady‐state free precession (SSFP) to detect myocardial edema in patients with an acute myocardial infarction.

Materials and Methods

This study was performed in a series of patients (n = 10) referred for the assessment of acute myocardial infarcts (AMI). Localizers were used to obtain true short axis views of the left ventricle (LV). These views were used to plan and obtain T2‐weighted STIR (short TI inversion recovery) images of the LV. These slices were then acquired using single‐shot dark blood‐prepared SSFP with a large (31) number of dummy pulses. Lastly, Contrast agent was injected, and late enhancement (LE) images were acquired. Images were analyzed using a multi‐segment model of the heart. SSFP images were compared with STIR images, with STIR images used as the standard of truth for the presence of edema. LE images were used to identify segments which were positive for microvascular obstruction.

Results

All techniques were successful in all patients. A total of 312 segments were analyzed. Excluding segments positive for microvascular obstruction, SSFP had a sensitivity/specificity of 80%/89%. Including segments positive for microvascular obstruction, sensitivity/specificity was 71%/88%. On a patient‐based analysis, no AMI was missed using SSFP (sensitivity = 100%).

Conclusion

Using single‐shot SSFP to detect myocardial edema in patients with AMI is feasible with a moderate sensitivity and high specificity. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.
Use of micro‐Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin
Authors: Frías Moisés , Martínez‐Ramírez Sagrario
Published: July 2009

Curing temperature is known to play an important role in the formation, development, and stability of the hydrated phases appearing during pozzolanic reactions (chemical reaction between puzzolanic addition, metakaolin (MK), and calcium hydroxide from cement hydration). A typical example of this important reaction is to be found in metakaolin‐bearing cement pastes, characterized by hexagonal phases whose thermodynamic stability declines with rising temperature. These phases cannot be exhaustively researched with traditional techniques (such as X‐ray diffraction) due to their poor crystallinity. Consequently, micro‐Raman spectroscopy was used in the present study to explore the behavior of white cement paste blends containing 0, 10, and 25% MK at two curing temperatures (20 and 60 °C). This led to the identification, for the first time using Raman spectroscopy, of phases C2ASH81 (stratlingite) and C3ASH6, which appear in the MK–white cement reaction. The CSH gel formed was characterized by Q1 dimers and a C/S ratio of 1.3–1.5. Raising the curing temperature favored the formation of C4AH13. Copyright © 2009 John Wiley & Sons, Ltd.
Progress in corrosion protection as a requirement for technical progress
Authors: Fürbeth W. , Schütze M.
Published: July 2009

In many of the more recent technologies, corrosion plays a crucial role in determining their successful application. The present paper identifies such important corrosion issues in a number of technologies, which are currently under development or have been recently discussed. In this sense, CO2 sequestration, fuel cells, offshore wind energy and other offshore technologies, geothermal energy, advanced coal conversion technologies, nuclear energy, light weight construction in transport, ionic liquids as well as medical technologies are discussed with respect to corrosion problems and existing research needs. In this way, this paper intends to show the complexity and the variety of corrosion topics of today and at the same time, point at the economic aspects and the impact on daily life. In the end, this leads to an introduction of the World Corrosion Organization and its study on future needs for research and development in materials degradation and corrosion control.
Interactions of 2,2,2‐trifluoroethanol with melittin
Authors: Neuman Robert C. , Gerig John T.
Published: July 2009

Melittin dissolved in 42% trifluoroethanol‐water at pH 2 has been shown to be α‐helical between residues 6 and 12 and between residues 13 and 25, with the two helical regions separated by a bend at the Leu13 residue. The inter‐helix angle was found to be 154 ± 3° at 0 °C and 135 ± 3° at 25 °C. The dominant conformation of the peptide is thus similar to those observed by previous workers for the peptide in a variety of media. At 25 °C, intermolecular nuclear Overhauser effects arising from nuclear spin dipole‐dipole interactions between melittin hydrogens and fluorines of the solvent are essentially those expected for a system that is homogeneous as regards concentration and translational diffusion of the peptide and fluoroalcohol components. However, at 0 °C, peptide‐trifluoroethanol cross‐relaxation terms are negative, a result consistent with the conclusion that fluoroalcohol molecules associate with the peptide for times (∼1 ns) that are long compared to the time of a typical peptide‐fluoroalcohol diffusive encounter (∼0.2 ns). Such interactions may be responsible for the reduction of the translational diffusion coefficient of trifluoroethanol produced by dissolved peptides. Copyright © 2009 John Wiley & Sons, Ltd.
Which voiding position is associated with lowest flow rates in healthy adult men? role of natural voiding position
Authors: Choudhury Sunirmal , Agarwal Mayank Mohan , Mandal Arup K. , Mavuduru Ravimohan , Mete Uttem K. , Kumar Santosh , Singh Shrawan K.
Published: July 2009

Purpose

To investigate the effect of voiding position on uroflowmetric variables and postvoid residual urine (PVR) volume in healthy adult men without lower urinary tract symptoms (LUTS).

Materials and Methods

Men without LUTS were enrolled. Participants were asked to report to the urodynamic suite with comfortably full bladder for uroflowmetry. Each participant performed six voids into digital uroflowmeter (Solar Silver, Medical Measurement System, The Netherlands), all on separate occasions, twice in each of the standing, sitting, and squatting down positions. PVR was measured using transabdominal ultrasound (Siemens®).

Results

Total 72 participants were enrolled and 61 completed the study; their mean (±SD) age was 26.6 ± 6.9 years. All of them but one was accustomed to void in standing and squatting positions. The mean maximal flow rates (Qmax) and average flow rates (Qave) were significantly lower in sitting position, than standing and squatting positions (Qmax: 19.8 ± 7.4 vs. 23.8 ± 7.7 and 24.4 ± 8.1 ml/sec, respectively; P = 0.0001. Qave: 11.2 ± 4.5 vs. 13.9 ± 4.5, and 13.8 ± 5.1 ml/sec, respectively; P = 0.0001). The corresponding values of voiding time were significantly higher (tvv: 38.6 ± 20.7 sec vs. 28.3 ± 15.3 and 30.6 ± 18.1 sec, respectively; P = 0.0001). The latter two positions were statistically similar in voiding characteristics. Voided volumes and PVR were statistically similar among all the three positions.

Conclusion

Uroflow parameters were higher in standing and squatting positions compared to sitting in individuals not accustomed to void in sitting position. Therefore, uroflowmetry should not be performed in a position the individual is not familiar with. Neurourol. Urodynam. 29:413–417, 2010. © 2009 Wiley‐Liss, Inc.
Bandwidth provisioning in ADSL access networks
Authors: Xiong Kaiqi , Perros Harry , Blake Steven
Published: July 2009

We consider an ADSL access network consisting of subscribers, digital subscriber line access multiplexers (DSLAMs), metro Ethernet switches and a broadband remote access aggregation server (BRAS). We obtain expressions for dimensioning the access network in the upstream direction. Specifically, we show that the bandwidth required at each DSLAM, metro Ethernet switch, and BRAS can be expressed as an exponential function of the subscribers in a log scale when the number of subscribers does not surpass a certain value. After this value, it grows linearly as a function of the subscribers. Copyright © 2009 John Wiley & Sons, Ltd.
Towards a professional civil service in post‐transition Romania
Authors: Lee Charlotte
Published: July 2009

To what degree and under what conditions can a young democracy build a competent, politically neutral public bureaucracy? A crucial component of the transition from communist party rule to democracy is the creation of a professional civil service. Success along this dimension of state‐building generates administrative capacity: non‐elected public officials ensure the implementation of reforms initiated by political leaders. In the communist party‐led regimes of Eastern Europe, forging this new administrative class from its highly politicised predecessor took place as new democracies sought to overcome historical legacies and integrate with the European Union. A case study of administrative reform in Romania during the post‐1989 period suggests the importance of external influences in forming a civil service more closely adhering to the Weberian ideal of an expert, rules‐based bureaucracy. Through analysis of survey data from a nationally representative sample of the Romanian civil servants, the public bureaucracy has professionalised insofar as educational and training credentials rather than political affiliation are significant predictors of salary levels. Copyright © 2009 John Wiley & Sons, Ltd.
Thermoluminescence and absorption spectra of MgO crystals irradiated by fast neutron fluxes of low intensity
Authors: Kvatchadze V. , Dekanozishvili G. , Abramishvili M. , Akhvlediani Z. , Galustashvili M. , Kalabegishvili T.
Published: July 2009

The influence of fast neutron fluxes of low intensity (106 n/cm2 s) on the thermally stimulated luminescence and optical and paramagnetic absorption spectra of nominally pure and impure MgO single crystals has been investigated. For all parameters studied by us, their polymodal dependence on the fluence was found: the effect increased at low fluences reaching the maximum, then decreased and increased again with the increase of fluence. The value of the low‐fluence maximum and the fluence at which it was reached, depended on the initial characteristics of samples.
The photoluminescence properties and reversible photoinduced spectral change of CeO2 bulk, film and nanocrystals
Authors: Mochizuki Shosuke , Fujishiro Fumito
Published: July 2009

The photoluminescence properties of different pristine CeO2 specimens (bulk crystal, film, and nanocrystals) have been studied at different temperatures between 7 K and room temperature. The photoinduced luminescence spectral change has been observed at room temperature for the first time. The phenomenon observed in a vacuum is explained as a photoinduced associative detachment of O2 on the specimen surface, while that observed in O2 gas is explained as a photoinduced dissociative adsorption of O2 on the specimen surface. The photoreduction is accompanied both by a valence number change of cerium ions (Ce4+ → Ce3+) and by oxygen‐defect formation. Such reversible photoinduced phenomena of CeO2 can be applied to light control of the oxygen‐storage and oxygen‐release processes at metal‐oxide surfaces. A tentative result obtained at room temperature for an oxygen‐storage material (0.3)CeO2‐(0.7)ZrO2 solid solution is also described.
Diversity and seasonal variability of bacterial community structure in the river Aliakmon, Greece: Analysis by the molecular technique fish
Authors: Tirodimos Ilias , Haidich Anna‐Bettina , Dardavessis Theodore , Arvanitidou Malamatenia
Published: July 2009

Aim

Fluorescence in situ hybridization (FISH) with rRNA‐targeted oligonucleotide probes was used to investigate the phylogenetic composition of bacterial community in samples from the river Aliakmon, the longest river in Greece. Diversity of bacterial community in different habitats of the same river, as well as seasonal variation, was also examined.

Methods and Results

Oligonucleotide probes specific for the domain Bacteria and five bacterial groups (high GC content, low GC content, Alpha‐, Beta‐ and Gammaproteobacteria) were used. The Gram‐positive populations were dominated by Firmicutes (low GC content), while Gammaproteobacteria showed increased abundances compared to Betaproteobacteria, although an enrichment step for samples was used, something which might had favoured the gamma subclass. Seasonal and along river variations were observed for Gram‐negative bacteria but not for Firmicutes.

Conclusions

We conclude that the changes in bacterial community composition was correlated with environmental conditions and resulted from interactions brought about by physical and biological factors. To our knowledge, this is the first study describing structure and diversity of a bacterial community in a Greek freshwater system, with the use of FISH. Copyright © 2009 John Wiley & Sons, Ltd.
The BUGS project: Evolution, critique and future directions
Authors: Lunn David , Spiegelhalter David , Thomas Andrew , Best Nicky
Published: July 2009

BUGS is a software package for Bayesian inference using Gibbs sampling. The software has been instrumental in raising awareness of Bayesian modelling among both academic and commercial communities internationally, and has enjoyed considerable success over its 20‐year life span. Despite this, the software has a number of shortcomings and a principal aim of this paper is to provide a balanced critical appraisal, in particular highlighting how various ideas have led to unprecedented flexibility while at the same time producing negative side effects. We also present a historical overview of the BUGS project and some future perspectives. Copyright © 2009 John Wiley & Sons, Ltd.
Assessment of seismic behaviour of SMRFs with RBS connections by means of mixed‐based state‐space approach
Authors: Kildashti K. , Mirghaderi R.
Published: July 2009

With an intention to implement a reliable numerical implementation of the mixed‐based state‐space strategy for steel structural systems, the paper presents a thorough seismic analysis of steel moment resisting frames (SMRFs) with reduced beam section (RBS) connections. Firstly, a model of beam‐column element inclusive of material and geometric nonlinearities is efficiently utilized derived from appropriate force interpolation functions. Moreover, with the present formulation, non‐prismatic properties of RBS region can be considered without the necessity of heavy discretization of elements. Contribution of panel zone is taken into account by considering a nonlinear rotational spring as well. In addition, the extension of Wen‐Bouc model to capture material inelasticity is applied that is apparently superior to other constitutive behaviour when it leads to both a smooth hysteretic model and rather precisely well‐mannered state‐space depiction capable of conveying several hysteretic features. The state‐space approach is then employed where nodal forces balance and constitutive equations are solved simultaneously. Secondly, three‐dimensional finite element analysis is surveyed to validate proposed macro‐element model. Finally, a set of nonlinear static and transient analyses of four‐ and eight‐storey frames with and without RBS connections are fulfilled. Then, structural demand parameters used to assess the global and local response of designated frames. Copyright © 2008 John Wiley & Sons, Ltd.
Drift optimization of high‐rise buildings in earthquake zones
Authors: Al‐Ansari Mohammed , Senouci Ahmed
Published: July 2009

This paper presents a Drift Design Structural Model (DDSM) for the design optimization of high‐rise buildings in seismic zones. The model is formulated as a Generalized Single Degree of Freedom System subjected to equivalent static seismic loadings. The model objectives are: (a) the minimization of the structure weight; (b) the minimization of the structure top drift; and (c) the uniform distribution of the inter‐story drifts over the building height in order to minimize earthquake damage through the increase in plastic ductility. Seven high‐rise buildings were analysed in order to validate the model, to illustrate its use and to demonstrate its capabilities in structural design optimization in earthquake zones. The results obtained show that the DDSM performed well and consequently can be of practical value to structural designers. Copyright © 2009 John Wiley & Sons, Ltd.
Preparation and Electrochemistry Properties of a New Polyoxometalate‐Based Supramolecular Assembly
Authors: Han Zhangang , Gao Yuanzhe , Wang Jiye , Hu Changwen
Published: July 2009

A polyoxometalate‐based supramolecular assembly with the formula (Hcpy)6H2[PMo12O40] (1) [cpy = 4‐(5‐chloropyridin‐2‐yl)pyridine] was prepared and characterized. Noncovalent intermolecular interactions including hydrogen bonds (N–H···O–Mo, N–H···H–N, and C–H···O–Mo), halogen (C–Cl···O–Mo), and face‐to‐face π packing coexist in crystal 1, which serves the insolubility of 1 in aqueous solution. Compound 1 was used as a solid material to fabricate a bulk‐modified carbon paste electrode by direct mixing. Electrochemistry results indicated that 1 is possessed of electrocatalytic activities toward the reduction reactions of chlorate, hydrogen peroxide, and nitrite.
Imaging Appearances of Congenital Thoracic Lesions Presenting in Adulthood
Authors: Hoey Edward T.D. , Bhatnagar Priya , Mankad Kshitij , Gopalan Deepa , Darby Michael , Robertson Roderick
Published: July 2009

Many congenital lesions of the thorax are detected for the first time in adulthood when they can simulate a wide range of pathologies, including infection and neoplasia. They can be broadly classified into tracheobronchial, parenchymal, vascular, and combined parenchymal/vascular abnormalities. An awareness of their typical imaging features enables a confident diagnosis and helps direct appropriate patient management.
Reduction of Adult Fingers Visualized on Pediatric Intensive Care Unit (PICU) Chest Radiographs after Radiation Technologist and PICU Staff Radiation Safety Education
Authors: Tynan Jennifer R. , Duncan Meghan D. , Burbridge Brent E.
Published: July 2009

Purpose

A recent publication from our centre revealed a disturbing finding of a significant incidence of adult fingers seen on the pediatric intensive care unit (PICU) chest radiographs. This is inappropriate occupational exposure to diagnostic radiation. We hypothesized that the incidence of adult fingers on PICU chest radiographs would decline after radiation safety educational seminars were given to the medical radiation technologists and PICU staff.

Methods

The present study's objectives were addressed by using a pretest-posttest design. Two cross-sectional PICU chest radiograph samples, taken before and after the administration of radiation safety education for our medical radiation technologists and PICU staff, were compared by using a χ2 test.

Results

There was a 61.2% and 76.9% reduction in extraneous adult fingers, directly exposed to the x-ray beam and those seen in the coned regions of the film, respectively, on PICU chest radiographs (66.7% reduction overall). This reduction was statistically significant (χ2 = 20.613, P < .001).

Conclusions

Limiting unnecessary occupational radiation exposure is a critical issue in radiology. There was a statistically and clinically significant association between radiation safety education and the decreased number of adult fingers seen on PICU chest radiographs. This study provides preliminary evidence in favour of the benefit of radiation safety seminars.
Impairment of twin‐arginine‐dependent export by seemingly small alterations of substrate conformation
Authors: Maurer Carlo , Panahandeh Sascha , Moser Michael , Müller Matthias
Published: July 2009

The twin‐arginine translocation (Tat) machinery is able to transport fully folded proteins across bacterial and thylakoidal membranes. Previous in vivo and in vitro studies indicated that the model Tat substrate TorA–PhoA acquires Tat‐competence only if its four cysteines form disulfide bonds. We now show that removal of the last 33 amino acids of PhoA, although not affecting the formation of disulfide bonds, converts TorA–PhoA into a poor Tat substrate. This finding suggests that even incomplete folding of a substrate can interfere with transport by the Tat translocase of Escherichia coli.
Mild cerebral hypoxia–ischemia produces a sub‐acute transient inflammatory response that is less selective and prolonged after a substantial insult
Authors: Qiao Min , Meng Shuzhen , Foniok Tadeusz , Tuor Ursula I.
Published: July 2009

Cerebral ischemia initiates various injurious processes including neuroinflammatory responses such as activation of microglia and increases in cytokine and nitric oxide release. Evidence primarily from in vitro studies, indicates that neuroinflammatory effects can be either beneficial or harmful, possibly related to stimulus strength. We investigated using in vivo models, the effect of a mild or substantial cerebral hypoxia–ischemia on: cerebral microglial/macrophage activation (ED1), pro‐inflammatory cytokines (tumor necrosis factor‐alpha), nitrosative stress (nitrotyrosine) and permanent brain damage. A mild insult produced a transient (1–2 days post) increase in activated microglia/macrophages within subcortical white and not gray matter but transiently increased cytokine or nitrotyrosine expression in cortex and not white matter. There was also prolonged scattered cell death in cortex and white matter over weeks along with loss of myelin/axons and cortical atrophy at 4 weeks post‐insult. In contrast, a substantial insult produced white and gray matter necrosis, cyst formation and atrophy, along with increases in tumor necrosis factor and nitrotyrosine staining within both white and gray matter starting at 1–2 days post‐insult. Microglial/macrophage staining was increased starting at 1‐week post a substantial insult and remained elevated for weeks thereafter.

Thus, a transient neuroinflammatory response occurs following a mild insult whereas prolonged scattered cell death occurs for weeks, particularly in white matter. Insult severity also affects the progression of the neuroinflammatory response, which is prolonged after a substantial insult. Effective therapy will need to be customized for insult severity and timing; and, monitoring the injury processes with imaging or biomarkers may help guide treatment.
Lipid analysis of a ground sloth coprolite
Authors: Gill Fiona L. , Crump Matthew P. , Schouten Remmert , Bull Ian D.
Published: July 2009

Coprolites can provide detailed information about the nutritional habits and digestive processes of the animals that produced them and may also yield information about the palaeoenvironment in which the animal existed. To test the utility of the lipid biomarker approach to coprolite analysis, lipids were extracted from a coprolite of the Pleistocene ground slothNothrotheriops shastensis. Gas chromatography/mass spectrometry results revealed a dominant spiroketal sapogenin component identified, using nuclear magnetic resonance spectroscopy, as epismilagenin. The dominance of epismilagenin is probably due to ingestion ofYuccaspp. andAgavespp., which is consistent with previous studies on the diet of this species.
Processes of auroral thermal structure at Jupiter: Analysis of multispectral temperature observations with the Jupiter Thermosphere General Circulation Model
Authors: Majeed T. , Waite J. H. , Bougher S. W. , Gladstone G. R.
Published: July 2009

We use our three‐dimensional Jupiter Thermosphere General Circulation Model (JTGCM) to quantify thermal processes that take place in the auroral thermosphere. These processes tend to control the thermal budget in the Jovian ovals and polar caps and maintain thermospheric temperatures consistent with those derived from multispectral observations of Jupiter's aurora. The main heat source in the JTGCM that drives the thermospheric flow is high‐latitude joule heating resulting from frictional motion of the ions relative to the neutrals. A secondary source of heating that dominates the exospheric region of the Jovian ovals is the auroral process of particle precipitation. Both sources of high‐latitude heating in the JTGCM are strongly related to the current system in the outer magnetosphere that allows plasma to flow in and out of the Jovian ionosphere. The mapping of this flow to ionospheric altitudes gives rise to an ion drag process that dominates the neutral momentum forcing near the altitude of the ionospheric peak. We find that the ion drag and joule heating inputs in the JTGCM significantly intensify the underlying global thermospheric circulation, thereby affecting the distribution of the neutral temperature. Global simulations of the Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to 1.9 km s−1 and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important mechanism for transporting significant amounts of auroral energy to the rest of the planet and for regulating the global heat budget in a manner consistent with temperature observations of Jupiter's oval and polar cap regions. Adiabatic expansion of the neutral atmosphere resulting from outward flows is found to be an important source of cooling for the auroral exosphere. The distribution of neutral temperature from 1 μbar to 1 nbar is determined by the thermal balance between the total heating caused by joule and adiabatic heating processes and dynamical cooling mainly from the hydrodynamic advection process. The thermal balance of the Jovian thermosphere below the homopause (≥1 μbar) is shown to be dominated primarily by wind transport processes. The heating in this region both for the Jovian ovals and polar caps is due to hydrodynamic advection and adiabatic compression processes. This dynamical heating is efficiently dissipated by hydrocarbon cooling through CH4 and C2H2 infrared radiation at 7.8 and 12.6 μm, respectively.
Acquiring Marine Data in the Canada Basin, Arctic Ocean
Authors: Hutchinson Deborah R. , Jackson H. Ruth , Shimeld John W. , Chapman C. Borden , Childs Jonathan R. , Funck Thomas , Rowland Robert W.
Published: July 2009

Despite the record minimum ice extent in the Arctic Ocean for the past 2 years, collecting geophysical data with towed sensors in ice‐covered regions continues to pose enormous challenges. Significant parts of the Canada Basin in the western Arctic Ocean have remained largely unmapped because thick multiyear ice has limited access even by research vessels strengthened against ice [Jackson et al., 1990]. Because of the resulting paucity of data, the western Arctic Ocean is one of the few areas of ocean in the world where major controversies still exist with respect to its origin and tectonic evolution [Grantz et al., 1990; Lawver and Scotese, 1990; Lane, 1997; Miller et al., 2006].
Modeling Hazardous Mass Flows Geoflows09: Mathematical and Computational Aspects of Modeling Hazardous Geophysical Mass Flows; Seattle, Washington, 9–11 March 2009
Authors: Iverson Richard M. , Leveque Randall J.
Published: July 2009

A recent workshop at the University of Washington focused on mathematical and computational aspects of modeling the dynamics of dense, gravity‐driven mass movements such as rock avalanches and debris flows. About 30 participants came from seven countries and brought diverse backgrounds in geophysics; geology; physics; applied and computational mathematics; and civil, mechanical, and geotechnical engineering. The workshop was cosponsored by the U.S. Geological Survey Volcano Hazards Program, by the U.S. National Science Foundation through a Vertical Integration of Research and Education (VIGRE) in the Mathematical Sciences grant to the University of Washington, and by the Pacific Institute for the Mathematical Sciences. It began with a day of lectures open to the academic community at large and concluded with 2 days of focused discussions and collaborative work among the participants.
Geodesy? What's That? My Personal Involvement in the Age‐Old Quest for the Size and Shape of the Earth
Authors: Morrison Foster
Published: July 2009

Imagine a story about a stay‐at‐home mother who, anticipating the departure of her children for college, takes a job at a government agency and by dint of hard work and persistence becomes a world‐renowned scientist. This might sound improbable, but it happens to be the true story of Irene K. Fischer, a geodesist and AGU Fellow. How it happened and the way it did is a fascinating and complex story.

In 1952, Fischer started working at the U.S. Army Map Service (AMS) in Brookmont, Md. (now part of Bethesda), at a time when computers were large, expensive, and feeble compared with the cheapest desktop personal computers available today. Much computing was still done on slow and noisy mechanical calculators. Artificial satellites, space probes, global positioning systems, and the like were science fiction fantasies.
Workshop on Marine Research Drilling: Cold‐Water Carbonate Reservoir Systems in Deep Environments (COCARDE): A Pilot Industry‐Academia Partnership in Marine Research Drilling; Fribourg, Switzerland, 21–24 January 2009
Authors: Spezzaferri Silvia
Published: July 2009

Cold‐water carbonate mounds supporting cold‐water coral ecosystems, often dominated by Lophelia pertusa and Madrepora oculata, are widespread along the Atlantic margins from Norway to Mauritania. During the past 10 years, the scientific community has accumulated new insights on their occurrence and development and identified their potential role in reservoir formation, thus establishing a framework for collaboration with the hydrocarbon industry.

A Magellan workshop, sponsored by the European Science Foundation (ESF; http://www.esf.org/), was held in Switzerland in January. The workshop gathered 35 scientists from 10 European and two extra‐European countries (Canada and Morocco), representing 20 research teams, including members of two Integrated Ocean Drilling Program (IODP) proposals. Some of the participants were also involved with two ESF European Collaborative Research (EUROCORES) projects [Microbial Diversity and Functionality in Cold‐Water Coral Reef Ecosystems (MiCROSYSTEMS) and Mid‐Latitude Carbonate Systems: Complete Sequences From Cold‐Water Coral Carbonate Mounds in the Northeast Atlantic (CARBONATE)], and the European Union Framework Program 6 integrated project Hotspot Ecosystem Research on the Margins of European Seas (HERMES).
A revised estimate of the processes contributing to global warming due to climate‐carbon feedback
Authors: Cadule P. , Bopp L. , Friedlingstein P.
Published: July 2009

Coupled climate‐carbon cycle models have shown that anthropogenic climate change has a negative effect on natural carbon sinks i.e., climate change induces a reduction in both land and ocean carbon uptake leading to an additional amount of CO2 in the atmosphere. Friedlingstein et al. (2006) concluded that such supplementary CO2 in the atmosphere would lead to an additional climate warming in 2100. However, as given by Friedlingstein et al. (2006), the role of non‐CO2 greenhouse gases (GHGs) and aerosols was neglected both for their direct impact on climate and their indirect impact on the carbon cycle. Besides, the climate models used for IPCC AR4 accounted for the radiative forcing of all GHGs and anthropogenic aerosols but neglected the climate‐carbon cycle feedback. In IPCC AR4, Meehl et al. (2007) attempted to reconcile these two methods in order to derive the global warming that would arise from both all anthropogenic forcings and climate‐carbon cycle feedback. Here we show that the approach they used is wrong for several reasons. First, as previously done by Friedlingstein et al. (2006), they considered that the warming is proportional to the change in atmospheric CO2 concentration. This assumption leads to consider that the gain in temperature is equal to the gain in CO2. However, because of the non‐linearity of the climate response to increased CO2 concentrations, the gain in temperature is lower than the gain in CO2. Second, they assumed that the temperature gains of the climate‐carbon cycle feedback generated by CO2, non‐CO2 GHGs and aerosols are all equal. We show here that, because of the specific spatial and temporal distribution of the radiative forcing exerted by those external perturbations, the temperature gains are all different. Based on our revised method, we found that, for the SRES A2 scenario, the projected global warming in 2100, due to increases in atmospheric CO2, non‐CO2 GHGs and anthropogenic sulphate aerosols, is 2.3–5.6°C. This is accidentally nearly equal to the original one of Meehl et al. (2007) (2.4–5.6°C).
Growth of embedded photonic crystals for GaN-based optoelectronic devices
Authors: Matioli Elison , Keller Stacia , Wu Feng , Choi Yong-Seok , Hu Evelyn , Speck James , Weisbuch Claude
Published: July 2009

We present three different techniques to fabricate embedded photonic crystals in GaN-based structures by metal organic chemical vapor deposition, geared toward high efficiency and high directionality light emitting diodes. Compared to the usual lateral epitaxial overgrowth, the novelty lies in the very short grating periods (varying from 180 to 350 nm) and the two-dimensional triangular nature of the grating. Coalescence was obtained over air-gap photonic crystals with thicknesses down to 70 nm, an essential requirement to obtain an efficient interaction between the optical guided modes and the photonic crystals. The quality and surface morphology of the overgrown layers were assessed by transmission electron microscopy and atomic force microscopy measurements. The thin coalesced GaN layer presented a fairly smooth surface (rms roughness of 1.27 nm for a 20×20 μm2 scan) with no extra defects created by the embedded photonic crystals.
Oxidant prepulsing of Ge (100) prior to atomic layer deposition of Al2O3: In situ surface characterization
Authors: Swaminathan Shankar , Oshima Yasuhiro , Kelly Michael A. , McIntyre Paul C.
Published: July 2009

We investigate the effects of H2O oxidant pulsing of Ge (100) substrates prior to Al2O3 atomic layer deposition (ALD) to synthesize metal-oxide-semiconductor devices. The prepulsing reduces the hysteresis in capacitance-voltage measurements from 490 to 30 mV at the flatband voltage and appears to reduce the density of fast interface states while causing a small increase in the midgap interface state density. Real-time x-ray photoelectron spectroscopy during prepulsing revealed the dynamic evolution of Ge–O bonding states and the formation of a surface layer with ∼70% hydroxyl termination which appears to produce a less defective interfacial region after subsequent Al2O3 ALD.
Directional dependence of AlN intrinsic complex dielectric function, optical phonon lifetimes, and decay channels measured by polarized infrared reflectivity
Authors: Kazan M. , Pereira S. , Correia M. R. , Masri P.
Published: July 2009

The directional dependence of AlN intrinsic complex dielectric function, the phonon lifetimes, and decay channels are investigated by means of polarized infrared reflectivity measurements on several facets of self-nucleated wurtzite AlN crystal of high crystalline quality. The measurement technique and the AlN single crystal used have been selected with the purpose to reduce, as much as possible, any instrumental-based effects as well as phonon scattering mechanisms due to defects. The experimental arrangements necessary to detect well-defined crystallographic orientations and phonons are detailed. The dielectric parameters and the phonon lifetimes are precisely determined as functions of the crystallographic direction from a careful Kramers–Kronig and damped Lorentz oscillator analysis. The ordinary (ε∞⊥) and extraordinary (ε∞∥) high frequency dielectric constants for high quality AlN crystal are found to be 3.93 and 4.05, respectively, and the ordinary (ε0⊥) and extraordinary (ε0∥) static dielectric constants are found to be 7.37 and 8.60, respectively. Our values obtained for the pure character phonon lifetimes are in good agreement with Raman measurements when these are obtained with the necessary care to eliminate linewidth broadening due to the finite slit width. The lifetime of a transversal phonon is found to increase with increasing the phonon energy, while that of a longitudinal phonon is found to decrease with increasing the phonon energy. Based on these observations, preferential decay channels for the AlN phonons are estimated. The results show that in the case of AlN, the widely assumed symmetric optical phonon decay into two phonons of lower energy cannot be justified for the zone center longitudinal phonons.
An improved treatment of spectator mode vibrations in reduced dimensional quantum dynamics: Application to the hydrogen abstraction reactions μ+CH4, H+CH4, D+CH4, and CH3+CH4
Authors: Banks Simon T. , Tautermann Christofer S. , Remmert Sarah M. , Clary David C.
Published: July 2009

A method for projecting chemical reaction surface coordinates from a Hessian in curvilinear internal coordinates has recently been developed. Here we introduce a modification to this approach which allows for analytical evaluation of the necessary coordinate derivatives, thus reducing the number of ab initio calculations required. We apply this method to the determination of spectator mode frequencies and zero-point energies for the series of hydrogen abstraction reactions X+CH4→XH+CH3, X=muonium (μ), H, D, CH3. Comparison of these frequencies with those obtained using rectilinear coordinates allows us to examine how the mass of X affects the coordinate sensitivity of the spectator modes. We carry out two-dimensional quantum reactive scattering calculations for these reactions to highlight instances where the choice of coordinates may have a significant impact on the evaluated thermal rate constants.
Toward C13 hyperpolarized biomarkers produced by thermal mixing with hyperpolarized X129e
Authors: Lisitza Natalia , Muradian Iga , Frederick Eric , Patz Samuel , Hatabu Hiroto , Chekmenev Eduard Y.
Published: July 2009

The C13 NMR signal of acetic acid 1-C13-AcH is enhanced by polarization transfer from hyperpolarized X129e using a thermal mixing procedure. 1-C13-AcH acid and hyperpolarized X129e are mixed as gases to disperse X129e in the acetic acid. The mixture is frozen with liquid N2 at 0.5 T. The magnetic field is then momentarily dropped to allow for exchange of spin polarization between C13 and X129e. After polarization exchange the magnetic field is raised to its original value and the mixture is thawed, resulting in a solution of polarization enhanced 1-C13-AcH. A C13 nuclear spin polarization enhancement of 10 is observed compared to its thermal polarization at 4.7 T. This polarization enhancement is approximately three orders of magnitude lower than that predicted by theory. The discrepancy is attributed to the formation of either an inhomogeneous solid matrix and/or spin dynamics during polarization transfer. Despite the low polarization enhancement, this is the first report of polarization transfer from X129e to C13 nuclear spins achieved by thermal mixing for a proton-containing molecule of biomedical importance. If future work can increase the enhancement, this method will be useful in hyperpolarizing a wide range of C13 enriched compounds important in biomedical and biophysical research.
Smart materials behavior in phosphates: Role of hydroxyl groups and relevance to antiwear films
Authors: Shakhvorostov Dmitry , Müser Martin H. , Song Yang , Norton Peter R.
Published: July 2009

The elastic properties of materials under high pressure are relevant to the understanding and performance of many systems of current interest, for example, in geology and tribology. Of particular interest is the origin of the dramatic increase in modulus with increasing pressure, a response which is also called “smart materials behavior.” In this context, simple phosphate-containing materials have been studied experimentally and theoretically, and the origins of this behavior have been associated with factors such as coordination of the cations and changes in the degree of polymerization and hydrogenation of the phosphate units. In the present paper we extend the former analysis on simple metal phosphate model compounds to so-called thermal films, an intermediate stage in the formation of effective antiwear films. The material was produced by heating a commercial zinc dialkyldithiophosphate (ZDDP), a common antiwear additive in lubricating oils, in poly-α-olefin base oil solutions to 150 °C, a process known to produce the thermal films. Its structure and equation of state were studied by means of x-ray diffraction and IR synchrotron radiation techniques during compression up to 25 GPa in a diamond anvil cell as well as during the subsequent decompression. As is the case for the simple metal phosphates, we find that the thermal films are relatively soft at low pressures but stiffen rapidly and ultimately amorphize irreversibly at high pressure. However, in addition to phase transformations involving cation sites occurring in the metal phosphates studied previously, thermal films undergo displacive transitions associated with instabilities of the hydroxyl groups. These results may imply that ZDDP ligands and those of the transformed materials not only affect ZDDP decomposition rate in engines but also the mechanical properties of the resulting antiwear films.
Atomic force microscopy and thermodynamics on taro, a self-cleaning plant leaf
Authors: Hüger E. , Rothe H. , Frant M. , Grohmann S. , Hildebrand G. , Liefeith K.
Published: July 2009

The evolution-optimized leaves of Colocasia esculenta (taro) and Nelumbo nucifera (lotus) are the best optimized self-cleaning surfaces known to date. Using an atomic force microscope device equipped with a piezodriven sample stage which enables a z-range of 100 μm we measured the surface morphology of dried and undried leaves of Colocasia esculenta. Thermodynamic calculations were done to investigate the interaction strength of a water droplet with the surfaces of the morphology shown in the images. The results show that the hierarchical structure produces a stable superhydrophobic state with optimal self-cleaning properties.
Hydrodynamic effects on the translocation rate of a polymer through a pore
Authors: Hernández-Ortiz Juan P. , Chopra Manan , Geier Stephanie , de Pablo Juan J.
Published: July 2009

The translocation of large DNA molecules through narrow pores has been examined in the context of multiscale simulations that include a full coupling of fluctuating hydrodynamic interactions, boundary effects, and molecular conformation. The actual rate constants for this process are determined for the first time, and it is shown that hydrodynamic interactions can lead to translocation rates that vary by multiple orders of magnitude when molecular weights are only changed by a factor of 10, in stark contrast to predictions from widely used free draining calculations.