bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Synthesis of Phosphorescent Iridium Containing Dendrimers for Potential Applications in Organic Light‐Emitting Diodes
Authors: Liu Qin‐De , Lu Jianping , Ding Jianfu , Tao Ye
Published: August 2008

Three phosphorescent dendrimers (IrC1, IrC3, and IrF2) with an iridium complex core and oligocarbazole or oligofluorene substituted ligands were synthesized and characterized. The structures of the oligocarbazole were designed to maintain high triplet energy of the ligands so that phosphorescence quenching in the resulting dendrimers can be prevented, while the oligofluorene in IrF2 resulted in undesired phosphorescence quenching. Best performance was obtained from an IrC3 based electrophosphorescent light‐emitting device with a maximum luminance of 13 060 cd · m−2 at a driving voltage of 11.5 V and a peak current‐efficiency of 4.3 cd · A−1 at a luminance of 3 400 cd · m−2, owing to its high PL efficiency, and efficient energy transfer between the iridium complex core and the ligands.

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Thermosensitive gradient copolymers by living cationic polymerization: Semibatch precision synthesis and stepwise dehydration‐induced micellization and physical gelation
Authors: Seno Ken‐Ichi , Tsujimoto Itsuko , Kikuchi Takunobu , Kanaoka Shokyoku , Aoshima Sadahito
Published: August 2008

Thermosensitive forced gradient copolymers with various sequence distributions were synthesized by living cationic polymerization in the presence of an added base. The synthesis was conducted using a semibatch reaction method, which is unfavorable for ionic polymerization, especially when a simple apparatus is employed. Polymerization of 2‐ethoxyethyl vinyl ether (EOVE) was initiated using a conventional syringe technique. Immediately after initiation, 2‐methoxyethyl vinyl ether (MOVE) was continuously added using a syringe pump at regulated feed rates, which allowed control of the sequence distribution. The resulting gradient copolymers of EOVE and MOVE underwent thermally induced association in water, forming micelles with a hydrophobic core derived from EOVE‐rich segments. Interestingly, the size of the micelles obtained from gradient copolymers decreased monotonously with increasing solution temperature, while the micelles of the corresponding block copolymers were unchanged in size. This self‐association behavior can be controlled by designing the gradient pattern of the instantaneous composition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6151–6164, 2008
Preparation of polyimide/silica hybrid material by sol–gel process under basic catalysis: Comparison with acid conditions
Authors: Didier Benoît , Mercier Régis , Alberola Nicole D. , Bas Corine
Published: August 2008

Hybrid polyimide/silica materials were prepared from polyimides bearing reactive functions along the polymer backbone, which can react with. The silica phase was formed by sol–gel process using ammonium hydroxide catalyst. Silica fillers prepared under basic conditions were compared with materials prepared using chlorhydric acid. The synthesized hybrid materials were characterized by TGA, IRTF, and NMR. The density of the different systems was also measured. The morphology of these hybrid systems were investigated by both scanning and transmission electron microscope. Thermal properties of the composites were also evaluated by DSC and DMA. The morphology of silica fillers highly depends on the catalyst, on the reaction conditions of the sol–gel process, and the linking formation with the polyimide. It results that optimized conditions lead to homogeneous hybrid films containing 12 wt % of silica particles of about 20 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1891–1902, 2008
Interaction of SWCNT and PPTA with sulfuric acid—Compatibilization of two materials in a common solvent
Authors: Vlasveld Daniel P. N. , Fischer Hartmut R. , Swierenga Erik , Picken Stephen J.
Published: August 2008

The results of a calorimetric study on the melting and crystallization behavior of concentrated sulfuric acid containing dispersed single wall carbon nanotubes (SWCNT), dissolved water, and dissolved poly‐p‐phenyleneterphthalate (PPTA) polymer are presented. The measured reduction of the heat of crystallization is caused by the build‐up of an associated layer of structured acid molecules around SWCNT and PPTA. The freezing point depression is related to the number of dissolved species such as ions. It is shown that this theory accurately describes the experimental data for dissolved water and sulfur trioxide, but not for large molecules such as SWCNT. A mechanism for the interaction between sulfuric acid and SWCNT is proposed, based on preferred adsorption of sulfur trioxide and dissociation of sulfuric acid, leading to an increased number of dissolved low‐molecular‐weight species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1914–1922, 2008
Investigation on LCST behavior of a new amorphous/crystalline polymer blend: Poly(n‐methyl methacrylimide)/poly(vinylidene fluoride)
Authors: Hu Huixia , Shangguan Yonggang , Zuo Min , Zheng Qiang
Published: August 2008

The liquid–liquid phase‐separation (LLPS) behavior of poly(n‐methyl methacrylimide)/poly(vinylidene fluoride) (PMMI/PVDF) blend was studied by using small‐angle laser light scattering (SALLS) and phase contrast microscopy (PCM). The cloud point (Tc) of PMMI/PVDF blend was obtained using SALLS at the heating rate of 1 °C min−1 and it was found that PMMI/PVDF exhibited a low critical solution temperature (LCST) behavior similar to that of PMMA/PVDF. Moreover, Tc of PMMI/PVDF is higher than its melting temperature (Tm) and a large temperature gap between Tc and Tm exists. At the early phase‐separation stage, the apparent diffusion coefficient (Dapp) and the product (2Mk) of the molecules mobility coefficient (M) and the energy gradient coefficient (k) arising from contributions of composition gradient to the energy for PMMI/PVDF (50/50 wt) blend were calculated on the basis of linearized Cahn‐Hilliard‐Cook theory. The kinetic results showed that LLPS of PMMI/PVDF blends followed the spinodal decomposition (SD) mechanism. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1923–1931, 2008
Reliability of performance‐based measures in people awaiting joint replacement surgery of the hip or knee
Authors: Gill Stephen , McBurney Helen
Published: August 2008

Background and Purpose. Understanding the reliability of selected measurement tools is a prerequisite to understanding the effects of clinical interventions. The aim of this investigation was to determine the reliability of the 50‐Foot Timed Walk (50 FTW) and 30‐second Chair Stand Test (30 CST) in subjects awaiting joint replacement surgery of the hip or knee. Methods. Eighty‐two subjects participating in a 6‐week exercise programme were assessed at baseline, 7 weeks and 15 weeks. Four trials of the 50 FTW and two trials of the 30 CST were completed at each assessment. Eleven trained assessors completed the assessments. Results. Intra‐class correlations were consistently high for the 50 FTW and 30 CST at all assessments. At the baseline assessment, trial 1 was found to be significantly different from subsequent trials for both the 50 FTW and 30 CST. This effect was not evident at the 7‐week and 15‐week assessments. At the baseline assessment, scores for the 50 FTW became stable after the first trial. Estimates of minimum detectable change indicated that participants needed to change by more than 3.08 seconds and 1.64 stands to be 90% confident that a real change had occurred for the 50 FTW and 30 CST, respectively. Conclusion. The 50 FTW and 30 CST can be reliable measures of physical performance. However, because we found a practice effect at the baseline assessment, a practice trial should be allowed before data collection begins. Because only two trials of the 30 CST were completed, further research is required to confirm whether scores at the initial assessment become stable on repeated testing. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of non‐selective non‐steroidal anti‐inflammatory drugs on the aggressiveness of prostate cancer
Authors: Stock David C. , Groome Patti A. , Siemens D. Robert , Rohland Susan L. , Song Zhi
Published: August 2008

BACKGROUND

Inflammatory mediators have a role in the initiation and progression of prostate cancer. Observed anti‐cancer effects of non‐steroidal anti‐inflammatory drugs (NSAIDs) have consisted largely of those that inhibit inflammatory mechanisms thought to promote an aggressive disease phenotype. Epidemiologic studies have supported a chemopreventive effect but there is little research on a possible protective role against prostate cancer aggressiveness and progression to advanced disease.

METHODS

We conducted a population‐based exploratory study, using cross‐sectional and case‐cohort approaches to assess, the effect of NSAIDs on indicators of prostate cancer aggressiveness. The study population consisted of 1,619 randomly selected patients with a further over‐sampling of 453 prostate cancer mortality cases. All had been curatively treated by radical prostatectomy or external‐beam radiotherapy and were sampled using the Ontario Cancer Registry. Aggressiveness of disease at diagnosis, represented by Gleason score, and risk of prostate cancer death were compared across NSAID exposure groups.

RESULTS

The adjusted odds ratio (OR) of a total Gleason score of 8–10 versus 2–6 indicated a non‐significant protective effect of NSAIDs (OR: 0.74, 95% CI: 0.47–1.17). We did not observe an association with risk of prostate cancer death overall (HR: 1.03, 95% CI: 0.79–1.34), but a secondary analysis indicated that NSAID users surviving five years may be protected from early prostate cancer death (HR: 0.54, 95% CI: 0.26–1.13).

CONCLUSION

Although estimates were not statistically significant, this exploratory study indicates a possible negative association between NSAID use and disease aggressiveness. Larger investigations with more precise exposure measurements are recommended. Prostate 68: 1655–1665, 2008. © 2008 Wiley‐Liss, Inc.
Pore growth on n ‐InP in liquid ammonia: electrode potential and morphology evolution
Authors: Eb A. , Gonçalves A.‐M. , Santinacci L. , Mathieu C. , Etcheberry A.
Published: August 2008

In this paper we report the pore formation onto n ‐InP (100) in acidic liquid ammonia at 223 K, by applying a constant current density of 2 mA·cm–2. The evolution of the electrode potential and the pore morphology has been investigated in this uncommon non‐aqueous medium. This solvent provides true water free and oxygen free conditions. Specific and reproducible electrochemical behaviour have been obtained. An original evolution of the porous structure has been observed by scanning electron microscopy. Tortuous current line oriented pores are formed. Pores are organized in hemispherical depressions and a multilayered structure is also evidenced. A three distinguished steps evolution has been established. In the first step, an insoluble passive layer is formed on surface, followed by the nucleation of the porous layer. The second phase corresponds to the formation of the first porous layer; while the third stage corresponds to the periodic lift‐off of the porous layer constituting thus a multilayered structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Neuronal dopamine transporter activity, density and methamphetamine inhibition are differentially altered in the nucleus accumbens and striatum with no changes in glycosylation in rats behaviorally sensitized to methamphetamine
Authors: Bjorklund Nicole L. , Sorg Barbara A. , Schenk James O.
Published: August 2008

Animals sensitized to methamphetamine (METH) have altered dopaminergic systems, including dopamine transporter (DAT) activity. We investigated the effects induced by a sensitizing dose (5 mg/kg, i.p. per day for 5 days) of METH on rat behavior, DA transport by the DAT, DAT density, and inhibition of DA transport by METH in both the nucleus accumbens and striatum. We further investigated possible changes to glycosylation of the DAT after METH sensitization. The dosing paradigm caused an increased stereotyped response in rats treated with METH compared with saline controls. In animals treated with METH, DA transport velocities were increased by 6.4% in the nucleus accumbens and decreased by 21% in the striatum. Western blots demonstrated that DAT density was unchanged in the nucleus accumbens of METH‐treated animals, but striatal DAT density was decreased by 20%. Further studies investigating METH inhibition of DA transport found that in the nucleus accumbens of METH‐treated animals, the IC50was shifted to a larger value (from 0.81 to 1.45 μM). In the striatum, the IC50was decreased by 19% (from 1.00 to 0.81 μM) in METH‐treated animals. Studies using glycosidase treatments and Western blots revealed that glycosylation was effectively removed byN‐glycanase and neuraminidase, but notO‐glycosidase or α‐mannosidase. These studies also suggest that glycosylation was not altered in METH‐treated animals. This study demonstrates that in animals sensitized to METH, the DAT is differentially regulated in different areas of the brain important for drug abuse, and that DA transport changes induced by METH are not due to DAT density, but to changes in the kinetics of the DAT. Additionally, this study suggests that glycosylation may not play a role in DAT activity changes after METH exposure. Synapse 62:736–745, 2008. © 2008 Wiley‐Liss, Inc.
Inhibition of endocannabinoid metabolism attenuates enhanced hippocampal neuronal activity induced by kainic acid
Authors: Coomber Ben , O'Donoghue Michael F. , Mason Robert
Published: August 2008

The endogenous cannabinoid system regulates neuronal excitability. The effects of inhibiting fatty acid amide hydrolase (FAAH), the enzyme responsible for metabolism of the endocannabinoid anandamide, on kainic acid (KA)‐induced neuronal activity were investigated in the rat in vivo, using the selective FAAH inhibitor URB597. Hippocampal neuronal ensemble unit activity was recorded in isoflurane‐anesthetized rats using 16‐wire microelectrode arrays. Separate groups of rats were administered with single doses of KA alone, KA and URB597 (0.3 or 1 mg kg−1, i.p.), or URB597 (1 mg kg−1) alone. The role of the cannabinoid CB1 receptor in mediating the effects of URB597 was explored using the CB1 selective antagonists AM251, either alone or prior to KA and URB597 (1 mg kg−1) administration, and SR141716A, administered prior to KA and URB597 (1 mg kg−1). Neuronal firing and burst firing rates were examined in animals with confirmed dorsal hippocampal placements. KA induced an increase in both firing and burst firing rates, effects which were attenuated by URB597 in a dose‐related manner. Pretreatment with AM251 or SR141716A partly attenuated the URB597‐mediated effects on firing and burst firing rate. Rats treated with AM251 or URB597 alone did not exhibit any significant change in either firing or burst firing rates compared with basal activity. These results suggest that the inhibition of endocannabinoid metabolism can suppress hyperexcitability in the rat hippocampus, partly via a CB1 receptor‐mediated mechanism. Synapse 62:746–755, 2008. © 2008 Wiley‐Liss, Inc.
Vanishing tumour of the internal auditory meatus
Authors: Jain A , Ablett M , Wardrop P
Published: August 2008

Objectives:

We report a very rare case of prostatic metastasis in the internal auditory meatus, which disappeared with treatment.

Case report:

An elderly man presented with a history of hearing loss, dizzy spells and, more recently, facial palsy. He also complained simultaneously of urological symptoms, which on investigation revealed advanced, metastatic prostate cancer. Radiological investigation, in the form of magnetic resonance imaging, revealed an internal auditory meatus mass which resembled an acoustic neuroma. The patient was treated with hormone injections.

Tumours of the internal auditory meatus and cerebellopontine angle are mostly primary. Rarely, metastatic deposits have been described in this region, from squamous cell carcinoma, malignant melanoma, malignant parotid oncocytoma, renal carcinoma, and lung and thyroid primaries.

Conclusion:

To our knowledge, this is a very rare report in the world literature of prostatic metastasis to the internal auditory meatus. We discuss the common presenting features, investigations and treatment options for metastatic prostatic tumours of the internal auditory meatus and cerebellopontine angle.
Dynamic behaviour of an oxygen dc discharge
Authors: RICHTER A. , TESTRICH H. , WAGNER H.-E. , LOFFHAGEN D. , WILKE C.
Published: August 2008

The dynamic behaviour of a positive column oxygen plasma is investigated both experimentally and theoretically. In the experiment the response of the discharge current to small external perturbations of the electrical field is measured. Using these data the electrical impedance of the plasma is obtained dependent on the frequency of the external perturbation. A drift approximation model is presented, which covers the experimental findings over a wide range of the perturbation frequency. It appears that the influence of the fluctuations of the neutral species is negligible and the dynamic behaviour of the plasma is mostly governed by the charged particles. This provides a simple expression for the plasma impedance which allows the reaction rate and transport coefficients, as well as discharge parameters, to be validated.
A CORBA-based simulation and control framework for mobile robots
Authors: Zhen Zhang , Qixin Cao , Lo Charles , Lei Zhang
Published: August 2008

This paper presents a distributed multiple mobile robots framework which allows programming and control of virtual and real mobile robots. The system provides the map building, path planning, robot task planning, simulation, and actual robot control functions in an indoor environment. Users can program the virtual robots in a customized simulation environment and check the performance of execution, i.e., if the simulation result is satisfying, users can download the code to a real robot. The paper focuses on the distributed architecture and key technologies of virtual robots simulation and control of real robots. A method for construction and transfer of a key index value (which stores the robot configuration) is proposed. Using this method, only the robot key configuration index is needed to build the robot in the virtual environment. This results in reduced network load and improved real time performance of the distributed system. Experiments were conducted to compare the performance of the proposed system with the performance of a centralized system. The results show that the distributed system uses less system resources and has better real time performance. What is more, this framework has been applied to Yaskawa's robot “SmartPal.” The simulation and experiment results show that our robotic framework can simulate and control the robot to perform complex tasks.
Accountability in morphological borrowing: Analyzing a linguistic subsystem as a sociolinguistic variable
Authors: Sanchez Tara
Published: August 2008

Principles of structural borrowing have been proposed, relating to structures of the languages involved and sociodemographic circumstances of their respective societies. This article quantitatively evaluates the roles of both linguistic and social factors in structural borrowing via examination of language contact data from Aruba and Curaçao, where creole Papiamentu is in contact with Spanish, Dutch, and English. Variationist methods, rooted in Labov's Principle of Accountability, are applied in a novel way to the system of verbal morphology to flesh out factors promoting borrowing. Linguistic factors are found to be quantitatively stronger, and only one nonlinguistic factor was found to promote borrowing. Results are discussed in light of prevailing theories of language contact. Findings contribute to our understanding of the long-term consequences of language contact and the relationship of contact-induced change to a more general sociolinguistic theory of language variation and change.
The Archbishop and Marital Pluralism: An American Perspective
Authors: Witte John
Published: August 2008

The Archbishop of Canterbury, Dr Rowan Williams (head of the worldwide Anglican Communion), set off an international firestorm on 7 February 2008 by suggesting that some accommodation of Muslim family law was ‘unavoidable’ in England. His suggestion, though tentative, prompted more than 250 articles in the world press within a month, the vast majority denouncing it. England will be beset by ‘licensed polygamy’, ‘barbaric procedures’ and ‘brutal violence’ against women and children, his critics argued, all administered by ‘legally ghettoized’ Muslim courts immune from civil appeal or constitutional challenge. Consider Nigeria, Pakistan and other former English colonies that have sought to balance Muslim sharia with the common law, other critics added. The horrific excesses of their religious courts – even calling the faithful to stone innocent rape victims for dishonouring their families – prove that religious laws and state laws on the family simply cannot coexist. Case closed.
RUSKIN AND HIS “GOOD MASTER,” WILLIAM BUCKLAND
Authors: Burd Van Akin
Published: August 2008

The enclosed having come into my hands being a Letter written by my Son to a Literary gentleman who had lent him a Work of Dr. Croly containing some remarks on your Rel Deluv, I having thought it might amuse you to see the Zeal of one of your Disciples, & therefore take the liberty of sending it, but I have a twofold motive believing that should your leisure ever allow of your glancing at the paper you might have an estimate of my Sons Knowledge of the Science he takes such delight in & aid him the more easily by occasional hints which the Intercourse so indulgently granted him by you may afford him the means of deriving.
Climate variability in the North Pacific thermocline diagnosed from oxygen measurements: An update based on the U.S. CLIVAR/CO2 Repeat Hydrography cruises
Authors: Mecking Sabine , Langdon Chris , Feely Richard A. , Sabine Christopher L. , Deutsch Curtis A. , Min Dong‐Ha
Published: August 2008

New observations of oxygen variability in the North Pacific Ocean are reported on the basis of comparison of the U.S. Climate Variability and Predictability and Carbon (CLIVAR/CO2) Repeat Hydrography sections conducted along 30°N (2004) and 152°W (2006) with the earlier World Ocean Circulation Experiment (WOCE) data and other cruises along these sections. The largest changes in apparent oxygen utilization (AOU) continue to occur, as found in earlier North Pacific repeat section analyses, within the thermocline on σθ = 26.6 kg m−3, which is the densest isopycnal to outcrop in the open North Pacific in climatological data. In the northeastern North Pacific along 152°W, where a total of five cruises (1980, 1984, 1991, 1997, and 2006) spanning a period of 26 years are available, the AOU changes correspond to an overall increase in AOU on σθ = 26.6 kg m−3 from the 1980s/early 1990s to 2006. However, from 1997 to 2006 a decrease in AOU is observed within the boundary region between the subtropical and subpolar gyres at 40°–45°N. Along the center axis of the subtropical gyre at 30°N, where two cruises are available (1994 and 2004), AOU has also substantially increased on σθ = 26.6 kg m−3 from 1994 to 2004 in the eastern part of the section. The repeat section data along 152°W and 30°N are consistent with a pattern of decadal‐scale ventilation anomalies that originate in the northwestern Pacific, possibly through variability (including cessation) of the σθ = 26.6 kg m−3 outcrop, travel eastward along the subtropical‐subpolar gyre boundary, and enter the northern portion of the subtropical gyre along the way. For the 152°W AOU data within the gyre boundary region (40°–45°N), good agreement exists with the close‐by time series data from Ocean Station P (50°N, 145°W) where a bidecadal cycle in AOU has been observed. In contrast, a sensible correlation with the Pacific Decadal Oscillation could not be found.
Atmospheric Fe deposition modes at Bermuda and the adjacent Sargasso Sea
Authors: Tian Zhenglong , Ollivier Patrick , Véron Alain , Church Thomas M.
Published: August 2008

The atmospheric fluxes of Fe and Al were determined from bulk (wet + dry) plus wet only deposition and aerosol samples collected at Bermuda from 1999 to 2001. During the sampling period, dry deposition accounted for majority (>70%) of total Fe deposition estimated by both modeled and measured means. This contrasts the North Pacific, where generally wet dominates dry deposition. This may be caused by the size and proximity of continental dust sources and seasonal patterns of precipitation to the North Atlantic. Comparing time series measurement of wet soluble Fe deposition indicates that the North Atlantic Oscillation (NAO) may impact the deposition mode of Fe in these areas. The dry deposition velocities of Fe‐bearing aerosols (DDVFe) were estimated from paired averages of measured dry deposition (bulk‐wet fluxes) divided by corresponding aerosol concentrations, and a seasonal trend was observed. During the summer months of 1999, the DDVFe ranged from 0.1 to 0.3 cm s−1; yet, during the fall and winter months, the DDVFe ranged from 2.0 to 6.0 cm s−1. It is hypothesized that with increased humidity and wind speeds at Bermuda during fall and winter, mineral aerosol particles could be internally mixed with sea salt and gaseous S and N pollutants to increase effective particle sizes. Such marine particle aggregation is reported elsewhere and could seasonally increase the apparent dry deposition velocity of mineral aerosols.
Dynamic pressure enhancements as a cause of large‐scale stormtime substorms
Authors: Lyons L. R. , Lee D.‐Y. , Zou S. , Wang C.‐P. , Kozyra J. U. , Weygand J. M. , Mende S. B.
Published: August 2008

Intense substorm disturbances, which typically have an unusually broad auroral enhancement, occur in association with magnetic storms. We have investigated the cause of these intense and broad disturbances using interplanetary observations, global auroral images from the WIC imager on the IMAGE spacecraft, geosynchronous energetic particle observations, and mid/low‐latitude dayside ground H observations for 28 large stormtime auroral disturbances. We find evidence that the magnetosphere was impacted by a substantial Pdyn increase at the onset of 19 of these disturbances. For disturbances with evidence of such an impact, we found that auroral brightenings extended over about twice as broad an MLT range as did the auroral brightening of disturbances that did not have evidence for a Pdyn increase at onset. We thus conclude that Pdyn increases at onset offer a feasible explanation for many of the larger‐scale aurora disturbances that often occur during magnetic storms. Our results indicate that it is the combination of the global compression response to a Pdyn increase and the nightside substorm response that gives a much broader response for many stormtime disturbances than is seen from the substorm alone. We also found some indications that a substantially shorter than typical growth phase may be sufficient for there to be a triggered substorm onset if the preceding IMF ∣By∣ or negative Bz, and/or a pressure increase at onset, is unusually large.
On the relationship between kinetic and fluid formalisms for convection in the inner magnetosphere
Authors: Song Yang , Sazykin Stanislav , Wolf Richard A.
Published: August 2008

In the inner magnetosphere, the plasma flows are mostly slow compared to thermal or Alfvén speeds, but the convection is far away from the ideal magnetohydrodynamic regime since the gradient/curvature drifts become significant. Both kinetic (Wolf, 1983) and two‐fluid (Peymirat and Fontaine, 1994; Heinemann, 1999) formalisms have been used to describe plasma dynamics, but it is not fully understood how they relate to each other. We explore the relations among kinetic, fluid, and recently developed “average” (Liu, 2006) models in an attempt to find the simplest yet realistic way to describe the convection. First, we prove analytically that the model of (Liu, 2006), when closed with the assumption of a Maxwellian distribution, is equivalent to the fluid model of (Heinemann, 1999). Second, we analyze the transport of both one‐dimensional and two‐dimensional Gaussian‐shaped blob of hot plasma. For the kinetic case, it is known that the time evolution of such a blob is gradual spreading in time. For the fluid case, Heinemann and Wolf (2001a, 2001b) showed that in a one‐dimensional idealized case, the blob separates into two drifting at different speeds. We present a fully nonlinear solution of this case, confirming this behavior but demonstrating what appears to be a shocklike steepening of the faster drifting secondary blob. A new, more realistic two‐dimensional example using the dipole geometry with a uniform electric field confirms the one‐dimensional solutions. Implications for the numerical simulations of magnetospheric dynamics are discussed.
Two overflows in the Northern Gulf of California
Authors: López Manuel , Candela Julio , García Joaquín
Published: August 2008

Two overflows, originating at sills in the northern Gulf of California, are marked by strong average downstream slopes of 17 and 4%. Near‐bottom stratification upstream of both sills is relatively strong, but the near‐bottom water is very well mixed downstream of the sills. The homogenization of a thick bottom layer downstream, albeit close to the sills, is indicative of very strong mixing. Waters in the downstream basins are well ventilated with relatively high oxygen concentrations. These hydrographic patterns were observed during three different seasons. Time series of temperature, salinity, and potential density show that water, flowing over the sills, is essentially subsurface, subtropical water from the Pacific Ocean. The time series also indicate that water is nearly always denser at the sills compared to water in the downstream basins, despite the two‐fold (∼800 m) and more than three‐fold (∼1500 m) increase in depth. The long‐term (more than a year) average current at both sills is bottom intensified with maximum average speeds of 33 and 17 cm/s. There are also strong tidal currents at the sills, although the subinertial currents near the bottom are quite persistent with nearly no flow reversals. Transports, estimated exclusively with the mean flow, are about 0.08 and 0.09 Sv (1 Sv = 1× 106, m3/s), which agree well with previous estimates based on shorter time series and a lower vertical resolution. These results indicate that the deep water at both downstream basins are renewed by these overflows, which enter at sill depths ≤400 m and are capable of reaching the deepest part of both basins. The overflows appear to be responsible for the main mechanisms that transform subsurface, subtropical water into Gulf of California water.
Dynamic controls on glacier basal motion inferred from surface ice motion
Authors: Howat Ian M. , Tulaczyk Slawek , Waddington Edwin , Björnsson Helgi
Published: August 2008

Current heuristic laws that relate the motion of glaciers due to sliding along the bed to the subglacial water pressure fail to reproduce variations in sliding speed on timescales of specific hydrologic events, such as lake drainage, rainfall, or surging. This may be due to the importance of subglacial cavity evolution and shifts in the glacier stress field, both of which are not accounted for in typical sliding laws. We use multiple time series of surface motion over a 66‐day period at Breiðamerkurjökull, Iceland, to infer changes in bed separation and longitudinal force budget. We observe multiple, distinct periods of increased surface motion and uplift corresponding to periods of rainfall and/or increased temperatures. We find consistent hysteresis and lags between motion and variations in both the bed separation and longitudinal stress gradient that we attribute to the redistribution of normal stresses at the bed during cavity growth. Increases in the longitudinal stress gradient suggest a downglacier stress transfer during increased basal motion that is consistent with increased drainage system efficiency toward the terminus. Our results suggest that the transient evolution of the subglacial drainage system and shifts in the glacier stress field are important controls on basal motion.
Development of a regional tropospheric delay model for GPS‐based navigation with emphasis to the Indian Region
Authors: Parameswaran K. , Saha Korak , Suresh Raju C.
Published: August 2008

The accuracy of Global Navigation Satellite System (GNSS), aimed to support precise positioning for aircraft navigation globally by coordinating different regional augmentation systems, is limited by the extent to which the atmospheric propagation delay of microwave signals can be modeled. An algorithm is developed for modeling the tropospheric delay based on mean meteorological parameters. A Region‐specific Tropospheric Delay (RTD) model is developed exclusively for the Indian region using meteorological data from the Indian subcontinent, as a part of GPS Aided Geo Augmented Navigation (GAGAN) program. The applicability of this model is examined in the context of the global model used in Wide Area Augmentation System (WAAS), developed employing meteorological data mostly from North American continent, by comparing the estimated zenith tropospheric delay (ZTD) with those obtained from regional models employing measured atmospheric parameters at the surface. The rms deviation of ZTD estimated using RTD model from that of the surface model is found to be ∼5 cm. A further validation by comparing with GPS measurements from two IGS stations at Bangalore and Hyderabad showed that predictions made using the RTD model are within an rms deviation of ±5 cm while those using WAAS model is ±7 cm. Maximum value of the residual error for RTD model is ∼15 cm, which corresponds to a ∼0.5 m error in the vertical coordinates for the lowest satellite elevation angles usually encountered.
Framework for Understanding Structural Errors (FUSE): A modular framework to diagnose differences between hydrological models
Authors: Clark Martyn P. , Slater Andrew G. , Rupp David E. , Woods Ross A. , Vrugt Jasper A. , Gupta Hoshin V. , Wagener Thorsten , Hay Lauren E.
Published: August 2008

The problems of identifying the most appropriate model structure for a given problem and quantifying the uncertainty in model structure remain outstanding research challenges for the discipline of hydrology. Progress on these problems requires understanding of the nature of differences between models. This paper presents a methodology to diagnose differences in hydrological model structures: the Framework for Understanding Structural Errors (FUSE). FUSE was used to construct 79 unique model structures by combining components of 4 existing hydrological models. These new models were used to simulate streamflow in two of the basins used in the Model Parameter Estimation Experiment (MOPEX): the Guadalupe River (Texas) and the French Broad River (North Carolina). Results show that the new models produced simulations of streamflow that were at least as good as the simulations produced by the models that participated in the MOPEX experiment. Our initial application of the FUSE method for the Guadalupe River exposed relationships between model structure and model performance, suggesting that the choice of model structure is just as important as the choice of model parameters. However, further work is needed to evaluate model simulations using multiple criteria to diagnose the relative importance of model structural differences in various climate regimes and to assess the amount of independent information in each of the models. This work will be crucial to both identifying the most appropriate model structure for a given problem and quantifying the uncertainty in model structure. To facilitate research on these problems, the FORTRAN‐90 source code for FUSE is available upon request from the lead author.
Modeling and observing the effect of aerosols on meteor radar measurements of the atmosphere
Authors: Younger J. P. , Reid I. M. , Vincent R. A. , Holdsworth D. A.
Published: August 2008

Measurements of the time taken for meteor radar echoes to decay can be used to estimate the ambipolar diffusion coefficient. If it is assumed that the decay of the radar echo is due strictly to the outward diffusion of ionized material in the meteor's trail, then echo decay is determined by temperature and pressure. However, dust particles or small ice crystals may absorb electrons from meteor trails, distorting their evolution and echo decay properties. A numerical method for modeling these processes is presented, with the prediction that absorbing aerosols can both decrease and increase the decay time of meteor radar echoes, depending on meteor, atmospheric, and radar parameters. This prediction is confirmed with observations taken using three 33 MHz and two 55 MHz radars at three locations in Australia and Antarctica, which display strong biases in the decay times of lower power echoes. It is suggested that both the accuracy and precision of atmospheric measurements are improved if only the highest power meteor echoes are used for estimates of the ambipolar diffusion coefficient.
Submesoscale activity over the Argentinian shelf
Authors: Capet X. , Campos E. J. , Paiva A. M.
Published: August 2008

Submesoscale activity over the Argentinian shelf is investigated by means of high resolution primitive equation numerical solutions. These reveal energetic turbulent activity (visually similar to the one occasionally seen in satellite images) at scales O(5 km) in fall and winter that is linked to mixed layer baroclinic instability. The air‐sea heat flux responsible for (i) deepening the upper ocean boundary layer (at these seasons) and (ii) maintaining a cross‐shelf background density gradient is the key environmental parameter controlling submesoscale activity. Implications of submesoscale turbulence are investigated. Its mixing efficiency estimated by computing a diffusivity coefficient is above 30 m2 s−1 away from the shallowest regions. Aggregation of surface buoyant material by submesoscale currents occurs within hours and is presumably important to the ecosystem.
Proposed re‐dating of the European ice core chronology by seven years prior to the 7th century AD
Authors: Baillie M. G. L.
Published: August 2008

Progress in the study of past climate change requires integration of historical documentation, tree‐ring data and ice‐core chemistry. Larsen et al. (2008) re‐evaluate volcanic acid signals in the Dye‐3, GRIP and NGRIP ice cores and identify large eruptions at 529 ± 2 and 533–534 ± 2; the latter claimed to cause the ‘dry fog’ of 536–537 and environmental consequences to 550; this conflicts with previous suggestions of a two stage environmental event; one in 536, the second c.540. Understanding the full range of natural hazards requires critical evaluation of the happenings in the mid‐6th century. This paper will show that 4 spaced tree‐ring responses to extreme environmental conditions in the 6th century can be used to re‐locate 4 key ice‐acid dates. Moving the ice‐core chronology forward 7 years places two large volcanoes in 536 and 541 explaining the extended duration of the 536–550 effects and anchoring the ice chronology.
Benthic primary productivity on the Georgia midcontinental shelf: Benthic flux measurements and high‐resolution, continuous in situ PAR records
Authors: Jahnke R. A. , Nelson J. R. , Richards M. E. , Robertson C. Y. , Rao A. M. F. , Jahnke D. B.
Published: August 2008

Continuous, 7 year records of above‐water, near‐surface water column and near‐bottom measurements of photosynthetically active radiation (PAR) were used in conjunction with in situ chamber measurements to estimate magnitude and seasonal variations in benthic primary productivity (BPP) on the Georgia continental shelf. Correlation between BPP and PAR flux was established with 19 light/dark benthic chamber and PAR flux measurements at water depths from 14 to 40 m. No substantial improvement in the relationship is observed by inclusion of benthic chlorophyll biomass and water temperature, apparently because variations in benthic chlorophyll concentrations are moderated by physical mixing processes and seasonal temperature ranges are relatively modest. Best fit for the data set is described by a simple power function [mg carbon fixed m−2 d−1 = 132(mol photon m−2 d−1)1.45]. In situ, continuous PAR measurements indicate temporal variations and seasonal trends not revealed by previous ship‐based measurements. Importantly, calculations of PAR flux and resulting BPP are significantly less than earlier estimates of benthic PAR derived via local insolation and water column light attenuation from ship‐based light profiling. Furthermore, benthic PAR flux based on continuous above‐water and near‐surface in‐water PAR measurements fails to correctly reflect seasonal trends for near‐bottom PAR. Analysis of the time series data suggests that estimates of the vertical attenuation coefficient for PAR (kPAR) values from ship‐based measurements are biased to calmer conditions while variations in the vertical profile of light attenuation prevent accurate estimates of benthic PAR from near‐surface or above‐water measurements. Accurate estimates of the benthic light field and BPP over the annual cycle require in situ, continuous, high‐resolution near‐bottom measurements provided by ocean observatories.
Mucosal immunology down under: Special Interest Group in Mucosal Immunology workshop, Australasian Society for Immunology, Sydney, Australia, 2 December 2007
Authors: Cripps Allan W , Sutton Philip , Beagley Ken , Robertson Sarah , Dunkley Margaret
Published: August 2008

The Mucosal Immunology Special Interest Group (SIG‐MI) of the Australasian Society of Immunology was formed 14 years ago and has run regular symposia and workshops in conjunction with the Australasian Society of Immunology since that time. In December 2007 the Mucosal Immunology Special Interest Group held a 1‐day satellite workshop in conjunction with the annual Australasian Society of Immunology scientific meeting in Sydney to celebrate the decade since hosting the 9th International Congress of Mucosal Immunology (9‐ICMI) in 1997, which was also held in Sydney. The meeting that was attended by 65 delegates focussed on 4 session themes: reproductive immunology, respiratory immunology, mucosal immunology of the gastrointestinal tract and mucosal vaccines.
Arfs and membrane lipids: sensing, generating and responding to membrane curvature
Authors: Donaldson Julie G.
Published: August 2008

Arf family GTP-binding proteins function in the regulation of membrane-trafficking events and in the maintenance of organelle structure. They act at membrane surfaces to modify lipid composition and to recruit coat proteins for the generation of transport vesicles. Arfs associate with membranes through insertion of an N-terminal myristoyl moiety in conjunction with an adjacent amphipathic α-helix, which embeds in the lipid bilayer when Arf1 is GTP-bound. In this issue of the Biochemical Journal, Lundmark et al. report that myristoylated Arfs in the presence of GTP bind to and cause tubulation of liposomes, and that GTP exchange on to Arfs is more efficient in the presence of liposomes of smaller diameter (increased curvature). These findings suggest that Arf protein activation and membrane interaction may initiate membrane curvature that will be enhanced further by coat proteins during vesicle formation.
Phosphodiesterase 4D gene polymorphism is associated with ischaemic and haemorrhagic stroke
Authors: Xue Hao , Wang Hu , Song Xiaodong , Li Weiju , Sun Kai , Zhang Weili , Wang Xiaojian , Wang Yibo , Hui Rutai
Published: August 2008

It has been reported that the variants of the PDE4D (phosphodiesterase 4D) gene are associated with stroke, especially with the combination of cardio-embolic and carotid stroke in the Icelandic population, but it is still very controversial as to whether PDE4D is a susceptible gene for stroke in other populations. In the present study, we tested whether the PDE4D gene variation also confers stroke risk in a Chinese population. Our hypothesis was tested in a case-control study of a Chinese population comprising 639 stroke patients (including 253 with cerebral thrombosis, 171 with lacunar infarction and 215 with intracerebral haemorrhage) and 887 healthy controls. Three SNPs (single nucleotide polymorphisms) (rs966221, rs456009 and rs2910829) in PDE4D were chosen based on the significant association with stroke reported previously in a Western population, and these were genotyped using PCR/RFLP (restriction-fragment-length polymorphism) and confirmed by sequencing. We found that only SNP83 (rs966221) was associated with stroke. Allele C of rs966221 is a risk allele, conferring an increased risk for atherothrombotic strokes [OR (odds ratio), 1.51; 95% CI (confidence interval), 1.09–2.10] independent of conventional risk factors. Haplotype analysis confirmed that haplotype G-C-C was associated with increased risk for atherothrombotic stroke (OR, 1.80; 95% CI, 1.300–2.491). Our findings support that SNP83 of PDE4D is a genetic risk factor for atherothrombotic strokes in a Chinese population.
Respiratory Movement Patterns During Vocalizations at 7 and 11 Months of Age
Authors: Reilly Kevin J. , Moore Christopher A.
Published: August 2008

Purpose

The present investigation was designed to study the modulation of abdomen and rib cage movements during vocalization over a period of development associated with rapid decreases in the compliance of the chest wall.

Method

Rib cage and abdominal kinematics were recorded during spontaneous vocalizations in 7- and 11-month old infants. Principal component analysis was used to represent each infant’s abdomen and rib cage traces as the weighted sum of a small number of principal component (PC) waveforms.

Results

The fundamental periods of infants' PC waveforms in the 11-month group were significantly shorter than those in the 7-month group. In addition, the variance contributed by PCs describing unidirectional patterns of respiratory movement decreased in the 11-month group, whereas the variances contributed by PCs describing modulated patterns of movement increased. Lastly, the extent to which abdomen and rib cage movements predicted the duration of corresponding vocalizations also increased significantly in the 11-month group compared with the 7-month group.

Conclusions

The findings of the present study were consistent with the hypothesis that decreases in the compliance of the chest wall result in more rapid modulation of chest wall movements and greater control of those movements by the developing neuromuscular system.