bluuebunny/crossref_metadata_2025 huggingface dataset:
Explaining turnover intention in Korean public community hospitals: occupational differences
Authors: Hwang Jee‐In , Chang Hyejung
Published: November 2006

Objectives

Personnel in public hospitals had relatively low job satisfaction despite of tenure employment. High turnover rates degrade hospital image and incur additional costs related to recruitment and training. The purposes of this study were to describe the occupational differences and to identify factors affecting turnover intention among public hospital personnel.

Method

A questionnaire survey was conducted as part of Administrative Services Quality Evaluation Program by Seoul metropolitan municipality from 1 November to 1 December in 2003. The subjects were 1251 entire hospital personnel in four hospitals. The questionnaire was designed to measure job satisfaction, organizational commitment, turnover intention, and demographic characteristics. Logistic regression analysis was performed to determine factors influencing turnover intention.

Results

There were significant differences in job satisfaction, organizational commitment, and turnover intention according to the occupations. The turnover intention rates were highest among physicians, followed by paramedicals and nursing staffs and then administrators. The significant factors affecting turnover intention were involvement and loyalty among physicians, hospital type, satisfaction with systems and loyalty among nursing staffs, satisfaction with relationship and loyalty among administrators, and loyalty among paramedicals.

Conclusion

There were different moderators that influence turnover intentions of hospital personnel. Loyalty had the most important effect upon turnover intention in all occupations. Copyright © 2006 John Wiley & Sons, Ltd.
Stability of alginate‐polyornithine microcapsules is profoundly dependent on the site of transplantation
Authors: Thanos C.G. , Bintz B.E. , Emerich D.F.
Published: November 2006

Alginate encapsulation is a form of cell‐based therapy with numerous preclinical successes but recalcitrant complications related to stability and reproducibility. Understanding how alginate stability varies across different transplant sites will help identify indications that might benefit most from this approach. Alginate stability has been quantified in the peritoneum, but there are no systematic studies comparing its relative stability across transplant sites. This study compares the stability of alginate‐polycation microcapsules implanted in the peritoneum to those implanted in the brain and subcutaneous space at 14, 28, 60, 90, 120, and 180 days in‐life. Using Fourier‐Transform Infrared Spectroscopy (FTIR), the surface of explanted capsules was analyzed for the relative proportion of alginate (outer coat) and the polycationic polyornithine (middle coat). Using a mathematic relationship between FTIR peaks related to these two material components, an index was generated to compare the stability of four different alginates. A notable difference was observed with rapid breakdown in the peritoneum. Conversely, identical alginate capsules transplanted into the brain or subcutaneous space were stable for the 6 month study. These data suggest that (1) successful intraperitoneal transplantation requires modifications of the capsule configuration, the host environment, or both and (2) that sites such as the brain and subcutaneous space are inherently less hostile to conventional alginate capsule configurations. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Effect of yeast extract on the expression of thioredoxin–human parathyroid hormone from recombinant Escherichia coli
Authors: Fu Xiang‐Yang , Wei Dong‐Zhi , Tong Wang‐Yu
Published: November 2006

Terrific broth, a complex medium containing a high content of yeast extract, was chosen to cultivate recombinant Escherichia coli with the plasmid encoding the fusion protein gene of thioredoxin (Trx) and human parathyroid hormone (hPTH). The volumetric yield of Trx–hPTH fusion protein in the culture with Terrific broth reached about 800 mg L−1 after optimization. It was found that high content of yeast extract in Terrific broth promoted cell growth and Trx–hPTH fusion protein production. However, the more interesting fact was confirmed that high content of yeast extract was also responsible for the high‐level expression of Trx–hPTH fusion protein without specific inducer addition. Further studies indicated that the expression levels of Trx–hPTH fusion protein without specific inducer addition varied greatly with the content and the source of yeast extract contained in the media. Considering that some proteins are toxic to the host and their continuous expression may result in decreasing plasmid stability and protein yields, one should be cautious in selecting yeast extract in media for cultivating E. coli with plasmids carrying toxic genes under T7 control. Copyright © 2006 Society of Chemical Industry
An investigation on the optimal location of ozonation within biological treatment for a tannery wastewater
Authors: Dogruel Serdar , Genceli Esra A , Babuna Fatos G , Orhon Derin
Published: November 2006

The objective of this study was to evaluate the optimal location of ozonation within biological treatment for a typical tannery wastewater by giving special attention to biodegradability‐based chemical oxygen demand (COD) characterization. As treating the raw tannery effluent solely by biological treatment is not adequate to meet the discharge standards owing to the high level of biorecalcitrant COD at the outlet, the application of chemical oxidation, i.e. ozone together with biotreatment (pre‐ozonation or in mid‐ozonation or post‐ozonation) was investigated. The tannery effluent under investigation had initially inert soluble COD (SI1) and particulate COD (XI1) fractions corresponding to 9% and 13% of the total COD (CT1), respectively, whereas each component of the biodegradable part—readily biodegradable COD (SS1), rapidly hydrolysable COD (SH1), and slowly hydrolysable COD (XS1)—accounted for around 26% of the total COD (CT1). Pre‐ozonation, undesirably competing with biotreatment for the removal of degradable organics, was shown to be insufficient both in terms of total COD (CT1) and inert COD (CI1) removal efficiencies. The scheme of biological treatment + ozonation + biological treatment could be applied successfully when 42.8 mg O3 min−1 was introduced for 5 min with a utilized ozone percentage of 76% at a point in biological treatment where the readily biodegradable COD (SS1) was depleted through biochemical reactions. Such an alternative yielded satisfactory outcomes when both total COD (CT) and inert COD (CI) removal efficiencies per utilized ozone ratios were considered. With post‐ozonation, on the other hand, the highest inert COD (CI) removal efficiencies together with an effluent quality meeting the discharge standards could be obtained. Copyright © 2006 Society of Chemical Industry
Removal of nickel(II) from aqueous solution by carbon nanotubes
Authors: Lu Chungsying , Liu Chunti
Published: November 2006

Single‐walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were oxidized by NaClO solutions and were employed as sorbents to study sorption characteristics of nickel(II) from aqueous solution. The surface properties of CNTs such as functional groups, total acidic sites and negatively charged carbons were greatly improved after oxidation, which made CNTs become more hydrophilic and resulted in sorption of more Ni2+. The amount of Ni2+ sorbed onto oxidized CNTs increased with a rise in agitation speed, initial Ni2+ concentration and solution pH in the range 1–8, but decreased with a rise in CNT mass and solution ionic strength. The sorption mechanisms are complicated and appear attributable to electrostatic forces and chemical interactions between the Ni2+ and the surface functional groups of the CNTs. The oxidized SWCNTs and MWCNTs have shorter equilibrium time and better Ni2+ sorption performance than the oxidized granular activated carbon, suggesting that both NaClO oxidized CNTs are efficient Ni2+ sorbents and that they possess good potential applications in water treatment. Copyright © 2006 Society of Chemical Industry
Computational comparison of reamed versus unreamed intramedullary tibial nails
Authors: Gómez‐Benito María José , Fornells Pere , García‐Aznar José Manuel , Seral Belén , Seral‐Iñnigo Fernando , Doblaré Manuel
Published: November 2006

We compared, via a computational model, the biomechanical performance of reamed versus unreamed intramedullary tibial nails to treat fractures in three different locations: proximal, mid‐diaphyseal, and distal. Two finite element models were analyzed for the two nail types and the three kinds of fractures. Several biomechanical variables were determined: interfragmentary strains in the fracture site, von Mises stresses in nails and bolts, and strain distributions in the tibia and fibula. Although good mechanical stabilization was achieved in all the simulated fractures, the best results were obtained in the proximal fracture for the unreamed nail and in the mid‐diaphyseal and distal fractures for the reamed nail. The interlocking bolts, in general, were subjected to higher stresses in the unreamed tibial nail than in the reamed one; thus the former stabilization technique is more likely to fail due to fatigue. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:191–200, 2007
Experimental validation of noninvasive referencing in navigated procedures on long bones
Authors: Kendoff Daniel , Bogojević Aleksander , Citak Musa , Citak Mustafa , Maier Christian , Maier Georg , Krettek Christian , Hüfner Tobias
Published: November 2006

Navigation procedures in orthopedic surgery require fixation of reference markers to the anatomic region of interest. Inadequate fixation might lead to micromotion or loosening of the reference marker, consequently causing registration failures or errors in navigation. Osseous rigid fixation is usually achieved by minimally invasive Schanz screws or pins. The goal of this study was to evaluate a non invasive external fixation device, a headband so far used in cranial navigation, as an alternative invasive fixation technique to reference markers in the femur. A common navigation system with an adapted trauma software application was used to track the positions of the soft tissue‐attached headband relative to an invasive reference marker on the femur during manipulations of the thigh. Relative translative and rotational movements of the headband were measured during defined movements of the hip and knee and manipulations of the headband itself. The results revealed high translative and rotational movements, up to 6 mm and 3°, respectively, due to minor manipulations of the affected lower extremity. Noninvasive soft tissue fixation with a headband does not allow rigid fixation for accurate navigated registration or operative procedures at the femur. Necessary intraoperative movements or manipulations would cause substantial registration failures. Invasive fixation techniques with screws or pins are still the method of choice. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:201–207, 2007
Effects of tungsten and nickel on repassivation rate of stainless steels in chloride solution by electrochemical method
Authors: Kim S.Y. , Kim H. , Kwan H.‐S.
Published: November 2006

The recent development of the method for analyzing repassivation rate by a rapid scratch test and high field conduction model makes it possible to predict SCC susceptibility more quantitatively but it is impossible to distinguish the repassivation rates with a little difference due to the inaccurate measurement of the scratched surface area. In addition, the electrochemical method previously reported as a method to remove passive film also makes it difficult to analyze repassivation rate by the high conduction model due to hydrogen evolution at the removing process. This study is to propose the new test conditions based on an electrochemical method and to get a better understanding of alloying elements on the repassivation rate of stainless steels. From the scratch test and the proposed electrochemical (potential step chronoamperometry: PSC) test, the function of nickel and tungsten affecting the repassivation rate is due to blocking the passivation by metal not participating in the formation of passive film and stabilizing the film by molybdenate (MoO42−) with accelerating the dissolution rate of iron by tungsten, respectively. In addition, the PSC test can be approved a technique for simulating the repassivation rate by the comparison of the results from two tests. Finally, the relationship between protectiveness of passive film and repassivation rate was mentioned.
Pregabalin (Lyrica) in the treatment of essential tremor
Authors: Zesiewicz Theresa A. , Ward Christopher L. , Hauser Robert A. , Pease Campbell Jessica A. , Sullivan Kelly L.
Published: November 2006

We report on 2 essential tremor patients who experienced marked improvement in upper extremity tremor with the use of pregabalin (Lyrica, PGB). On PGB 200 mg/day, tremor amplitude was reduced by at least 40% in the worst affected hand in both patients as measured by accelerometry. Both patients also reported moderate reduction in tremor on the Clinical Global Impression Scale, and Fahn–Tolosa–Marin Part I scores were markedly improved. © 2006 Movement Disorder Society
Detection of an antioxidant profile in the human brain in vivo via double editing with MEGA‐PRESS
Authors: Terpstra Melissa , Marjanska Malgorzata , Henry Pierre‐Gilles , Tkáč Ivan , Gruetter Rolf
Published: November 2006

Vitamin C (ascorbate) and glutathione (GSH) are the two most concentrated non‐enzymatic antioxidants in the human brain. Double editing with (DEW) MEGA‐PRESS at 4T was designed in this study to measure both antioxidants in the same amount of time previously required to measure one. In the occipital lobe of four human subjects, resolved ascorbate (Asc) and GSH resonances were detected repeatedly and simultaneously using DEW MEGA‐PRESS. The Asc and GSH concentrations measured using LCModel analysis of DEW MEGA‐PRESS spectra were 0.8 ± 0.1 and 1.0 ± 0.1 μmol/g (mean ± SD), with average Cramer‐Rao lower bounds (CRLB) of 10% and 7%, respectively. Aside from the effects of J‐modulation at a common echo time (TE), double editing did not compromise sensitivity. To determine the extent to which the oxidized forms of Asc and GSH contribute to DEW MEGA‐PRESS spectra in vivo, chemical shifts and coupling constants for dehydroascorbate (DHA) and oxidized glutathione (GSSG) were measured at physiologic pH and temperature. DHA does not contribute to the 3.73 ppm DEW MEGA‐PRESS Asc resonance. GSSG contributions to the DEW MEGA‐PRESS GSH resonance (3.0 ppm) are negligible under physiologic conditions, and would be evidenced by a distinct GSSG resonance (3.3 ppm) at exceptionally high concentrations. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
High‐resolution DTI of a localized volume using 3D single‐shot diffusion‐weighted STimulated echo‐planar imaging (3D ss‐DWSTEPI)
Authors: Jeong Eun‐Kee , Kim Seong‐Eun , Kholmovski Eugene G. , Parker Dennis L.
Published: November 2006

Diffusion tensor MRI (DTI) using conventional single‐shot (SS) 2D diffusion‐weighted (DW)‐EPI is subject to severe susceptibility artifacts. Multishot DW imaging (DWI) techniques can reduce these distortions, but they generally suffer from artifacts caused by motion‐induced phase errors. Parallel imaging can also reduce the distortions if the sensitivity profiles of the receiver coils allow a sufficiently high reduction factor for the desired field of view (FOV). A novel 3D DTI technique, termed 3Dsingle‐shotSTimulatedEPI(3D ss‐STEPI), was developed to acquire high‐resolution DW images of a localized region. The new technique completesk‐space acquisition of a limited 3D volume after a single diffusion preparation. Because the DW magnetization is stored in the longitudinal direction until readout, it undergoesT1rather thanT2decay. Inner volume imaging (IVI) is used to limit the imaging volume. This reduces the time required for EPI readout of each completekx‐kyplane, and hence reducesTdecay during the readout andT1decay between the readout of eachkz. 3D ss‐STEPI images appear to be free of severe susceptibility and motion artifacts. 3D ss‐STEPI allows high‐resolution DTI of limited volumes of interest, such as localized brain regions, cervical spinal cord, optic nerve, and other extracranial organs. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Ex vivo identification of atherosclerotic plaque calcification by a 31P solid‐state magnetic resonance imaging technique
Authors: Hallock Kevin J. , Hamilton James A.
Published: November 2006

Calcified tissue is a common component of atherosclerotic plaques, and occurs most often in mature plaques. The process of calcification is a poorly understood risk factor that may contribute to a plaque's vulnerability to sudden rupture. In this study a solid‐state imaging sequence, termed single‐point imaging (SPI), was used to observe calcification directly in ex vivo atherosclerotic plaques. Standards were used to validate the ability of 31P SPI to detect and differentiate calcification from crystalline cholesterol, phospholipids, and other plaque components. After suitable experimental parameters were found, human carotid specimens obtained by endarterectomy were imaged ex vivo by 31P solid‐state imaging and standard 1H methods. In contrast to 1H imaging methods, 31P imaging detected only the calcification in the plaque. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Targeted PARACEST nanoparticle contrast agent for the detection of fibrin
Authors: Winter Patrick M. , Cai Kejia , Chen Junjie , Adair Christopher R. , Kiefer Garry E. , Athey Phillip S. , Gaffney Patrick J. , Buff Carolyn E. , Robertson J. David , Caruthers Shelton D. , Wickline Samuel A. , Lanza Gregory M.
Published: November 2006

A lipid‐encapsulated perfluorocarbon nanoparticle molecular imaging contrast agent that utilizes a paramagnetic chemical exchange saturation transfer (PARACEST) chelate is presented. PARACEST agents are ideally suited for molecular imaging applications because one can switch the contrast on and off at will simply by adjusting the pulse sequence parameters. This obviates the need for pre‐ and postinjection images to define contrast agent binding. Spectroscopy (4.7T) of PARACEST nanoparticles revealed a bound water peak at 52 ppm, in agreement with results from the water‐soluble chelate. Imaging of control nanoparticles showed no appreciable contrast, while PARACEST nanoparticles produced >10% signal enhancement. PARACEST nanoparticles were targeted to clots via antifibrin antibodies and produced a contrast‐to‐noise ratio (CNR) of 10 at the clot surface. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Integer programming formulations for the two 4‐hop‐constrained paths problem
Authors: Huygens David , Ridha Mahjoub A.
Published: November 2006

In this article, we consider the two 4‐hop‐constrained paths problem, which consists, given a graph G = (N,E) and two nodes s,t ∈ N, of finding a minimum cost subgraph in G containing at least two node‐ (resp., edge‐) disjoint paths of length at most 4 between s and t. We give integer programming formulations, in the space of the design variables, for both the node and edge versions of this problem. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 49(2), 135–144 2007
Quantification of spiroether isomers and herniarin of different parts of Matricaria matricarioides and flowers of Chamaemelum nobile
Authors: Ma Chao‐Mei , Winsor Linda , Daneshtalab Mohsen
Published: November 2006

A simple HPLC‐PAD‐MS method was established to quantitatively analyse two spiroether isomers (cis‐en‐yn‐dicycloether and trans‐en‐yn‐dicycloether) and the main coumarin, herniarin, in chamomile herbs, simultaneously. By using this method, the contents of these three compounds in the flowers of two chamomile species, Roman chamomile (Chamaemelum nobile) and pineapple weed (Matricaria matricarioides), as well as in different parts of pineapple weed, were investigated. It was found that the flowers of both herbs contained large amounts of cis‐en‐yn‐dicycloether and trans‐en‐yn‐dicycloether, with the trans‐form being more abundant than the cis‐form. The leaves of pineapple weed were found to have the highest concentration of cis‐en‐yn‐dicycloether and herniarin than the other parts. HPLC‐PAD‐MS‐guided isolation and identification of other constituents are also discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Association between nonnaproxen NSAIDs, COX‐2 inhibitors and hospitalization for acute myocardial infarction among the elderly: a retrospective cohort study
Authors: Rahme Elham , Watson Douglas J. , Kong Sheldon X. , Toubouti Youssef , LeLorier Jacques
Published: November 2006

Purpose

To evaluate the association between rofecoxib, celecoxib, diclofenac, and ibuprofen and the risk of hospitalization for acute myocardial infarction (AMI) in an elderly population.

Methods

We conducted a retrospective cohort study, using data from the government of Quebec health insurance agency databases, among patients 65–80 years of age who filled a prescription for any of the study drugs during 1999–2002. Cox regression models with time‐dependent exposure were used to compare the incidence rates of hospitalization for AMI adjusting for patients' baseline characteristics. Analyses stratified by dose and number of supplied days were also conducted.

Results

At the index date, a total of 91 062 patients were taking rofecoxib, 127 928 celecoxib, 49 193 diclofenac, and 15 601 ibuprofen. The adjusted hazard ratio (HR) (95%CI) of hospitalization for AMI were: celecoxib versus rofecoxib: 0.90 (0.79, 1.01); ibuprofen versus rofecoxib: 0.95 (0.65, 1.37); diclofenac versus rofecoxib: 1.01 (0.84, 1.22). In secondary analyses based on intended duration of use, neither COX‐2 selective inhibitor was associated with a higher risk than ibuprofen or diclofenac. The unadjusted risk of AMI for all NSAIDs increased with dose. In the direct two way adjusted comparison of each NSAID stratified by dose, the only statistically significant difference was with rofecoxib >25 mg/day versus celecoxib >200 mg/day.

Conclusion

In this study there was no difference between AMI occurrence in elderly patients taking rofecoxib or celecoxib at recommended doses for chronic indications versus those taking ibuprofen/diclofenac. However, the risk of AMI was higher among patients using higher doses of rofecoxib (>25 mg/day) compared to patients using higher doses of celecoxib (>200 mg/day). Copyright © 2006 John Wiley & Sons, Ltd.
Miniemulsion polymerization initiated by L‐ascorbic acid and sulfonate/sulfate surfactants
Authors: Osti Martina , Cunningham Michael F. , Whitney Ralph , Keoshkerian Barkev
Published: November 2006

Styrene miniemulsions that were stabilized by common anionic surfactants (sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and disulfonated alkyl diphenyl oxide sodium salt) polymerized at 25 °C in the presence of L‐ascorbic acid without the addition of a free‐radical initiator. The polymerizations exhibited high rates and molecular weights, with conversions greater than 70% achieved in less than 1 h and weight‐average molecular weights greater than 1 × 106 g/mol. Polymers did not form in the absence of L‐ascorbic acid. Although the final conversion was only slightly independent on the L‐ascorbic acid concentration, it was dependent on the surfactant concentration. The rate and final conversion were also strongly dependent on the surfactant type. Moreover, it was possible to initiate polymerizations with a monomer‐soluble derivative of L‐ascorbic acid (L‐ascorbic acid 6‐palmitate), although the rates were dramatically reduced compared with those when water‐soluble L‐ascorbic acid was used. High yields and high‐molecular‐weight polymers were also produced with butyl acrylate and methyl methacrylate with L‐ascorbic acid in the presence of sodium dodecyl benzene sulfonate. The initiation was attributed to an interaction between the surfactant and L‐ascorbic acid, which formed a redox initiation system that generated radicals capable of adding monomer. These results are of particular significance for redox‐initiated emulsion/miniemulsion polymerizations with L‐ascorbic acid as the reducing agent and with sulfate or sulfonate surfactants. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 69–80, 2007
Synthesis of poly(vinyl acetate)‐b‐polystyrene and poly(vinyl alcohol)‐b‐polystyrene copolymers by cobalt‐mediated radical polymerization
Authors: Bryaskova Rayna , Willet Nicolas , Debuigne Antoine , Jérôme Robert , Detrembleur Christophe
Published: November 2006

Well‐defined poly(vinyl acetate) macroinitiators, with the chains thus end‐capped by a cobalt complex, were synthesized by cobalt‐mediated radical polymerization and used to initiate styrene polymerization at 30 °C. Although the polymerization of the second block was not controlled, poly(vinyl acetate)‐b‐polystyrene copolymers were successfully prepared and converted into amphiphilic poly(vinyl alcohol)‐b‐polystyrene copolymers by the methanolysis of the ester functions of the poly(vinyl acetate) block. These poly(vinyl alcohol)‐b‐polystyrene copolymers self‐associated in water with the formation of nanocups, at least when the poly(vinyl alcohol) content was low enough. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 81–89, 2007
Time‐varying linear controllers for exponential tracking of non‐holonomic systems in chained form
Authors: Tian Yu‐Ping , Cao Ke‐Cai
Published: November 2006

In this paper, the authors address the tracking problem for non‐holonomic systems in chained form with target signals that may exponentially decay to zero. By introducing a time‐varying co‐ordinate transformation and using the cascade‐design approach, smooth time‐varying controllers are constructed, which render the tracking‐error dynamics globally 𝒦‐exponentially stable. The result shows that the popular condition of persistent excitation or not converging to zero for the reference signals is not necessary even for the globally 𝒦‐exponential tracking of the chained‐form system. The effectiveness of the proposed controller is validated by simulation of two benchmark mechanical systems under non‐holonomic constraints. Copyright © 2006 John Wiley & Sons, Ltd.
Robustness of linear uncertain sampled‐data control systems with generalized sampled‐data hold functions
Authors: Jin Hui‐Liang , Mirkin Leonid , Palmor Zalman J.
Published: November 2006

This paper investigates robust stability of linear time‐invariant (LTI) uncertain sampled‐data control systems with generalized sampled‐data hold functions (GSHFs). A new sufficient condition for robust stability of such systems is developed. Unlike that of most of the previous works, it directly uses the data of the continuous‐time plant and therefore it is less conservative. The condition is expressed in terms of the spectral radius of a certain matrix and is shown to be a unimodal function of a free parameter. This property enabled us to use standard one‐dimensional optimization algorithm to perform the proposed test. Copyright © 2006 John Wiley & Sons, Ltd.
Brachycephaly and frontal lobe hypoplasia in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks
Authors: Borenstein M. , Dagklis T. , Csapo B. , Sotiriadis A. , Nicolaides K. H.
Published: November 2006

Objective

To investigate the incidence of brachycephaly and frontal lobe hypoplasia in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation.

Methods

A three‐dimensional (3D) volume of the fetal head was obtained before fetal karyotyping at 11 + 0 to 13 + 6 (median, 12 + 5) weeks of gestation in 100 fetuses that were subsequently found to have trisomy 21 and in 300 fetuses subsequently found to be chromosomally normal. The multiplanar mode was used to obtain a sequence of transverse views of the fetal head and to demonstrate the biparietal and suboccipitobregmatic views. We measured the biparietal diameter (BPD), the occipitofrontal diameter (OFD) and the frontothalamic distance (FTD) between the inner table of the frontal bone and the posterior thalami.

Results

In the chromosomally normal group the BPD, OFD and FTD increased linearly with crown–rump length (CRL) from 16.7 mm, 19.0 mm and 12.1 mm at a CRL of 45 mm to 26.7 mm, 31.7 mm and 18.7 mm, respectively, at a CRL of 84 mm. In the trisomy 21 fetuses, compared to normal fetuses, there was shorter BPD (mean difference = −0.63 mm; 95% CI, −0.97 to −0.30 mm, P < 0.0001), OFD (mean difference = −1.41 mm; 95% CI, −1.75 to −1.07 mm, P < 0.0001) and FTD (mean difference = −0.77 mm; 95% CI, −1.02 to −0.54 mm; P < 0.0001) and higher BPD to OFD ratio (mean difference = 0.022; 95% CI, 0.012 to 0.032, P < 0.0001) but no significant difference in the FTD to OFD ratio (mean difference = 0.004; 95% CI, −0.006 to 0.013, P = 0.448).

Conclusions

In fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation there is evidence of brachycephaIy but not of frontal lobe hypoplasia. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Right aortic arch detected in fetal life
Authors: Berg C. , Bender F. , Soukup M. , Geipel A. , Axt‐Fliedner R. , Breuer J. , Herberg U. , Gembruch U.
Published: November 2006

Objective

To evaluate the prenatal distribution, associated conditions and outcome of the different types of right aortic arch (RAA) detected in fetal life.

Methods

This was a retrospective review of all cases of RAA detected prenatally between 1998 and 2005 in two tertiary referral centers.

Results

In the study period 71 cases of RAA were detected; 26 (37%) had RAA with aberrant left subclavian artery, 23 (32%) had RAA with mirror‐image branching, 20 (28%) had RAA of unknown type and two (3%) had double aortic arch. While 20/26 cases with RAA and aberrant left subclavian artery were isolated findings, all 23 cases with RAA and mirror‐image branching were associated with cardiac defects, namely tetralogy of Fallot (43%) or pulmonary atresia with ventricular septal defect (22%). Of the 20 cases with RAA, 19 of unknown type were associated with heterotaxy syndromes and had additional cardiac malformations and ambiguities of the situs. The two cases with DAA were isolated findings. Seven cases in our series (10%) had a microdeletion 22q11 and these were significantly associated with extracardiac malformations. The outcome in our series depended solely on the associated cardiac and extracardiac malformations, with the exception of one infant with isolated DAA, in whom a surgical correction was warranted.

Conclusions

RAA detected in fetal life is associated frequently with other cardiac/non‐cardiac malformations, heterotaxy syndromes and microdeletions 22q11. The associated conditions vary depending on the branching type of the brachiocephalic vessels and the presence of extracardiac malformations. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Processability and characterization of poly(vinyl chloride)‐b‐poly(n‐butyl acrylate)‐b‐poly(vinyl chloride) prepared by living radical polymerization of vinyl chloride. Comparison with a flexible commercial resin formulation prepared with PVC and dioctyl phthalate
Authors: Coelho Jorge F.J. , Carreira Mafalda , Gonçalves Pedro M.O.F. , Popov Anatoliy V. , Gil Maria H.
Published: November 2006

This work reports the synthesis and processing of a new flexible material based on PVC produced by living radical polymerization. The synthesis was carried out in a two‐step process. In the first step the macroinitiator α, ω‐di(iodo)poly(butyl acrylate) [α, ω‐di(iodo)PBA] was synthesized in water by single electron transfer/degenerative chain transfer mediated living radical polymerization (SET‐DTLRP) catalyzed by Na2S2O4. In the second step this macroinitiator was reinitiated by SET‐DTLRP of vinyl chloride (VC), thereby leading to the formation of the block copolymer poly(vinyl chloride)‐b‐poly(butyl acrylate)‐b‐poly(vinyl chloride) [PVC‐b‐PBA‐b‐PVC]. This new material was processed on a laboratory scale. The DMTA traces showed only a single glass transition temperature, thus indicating that no phase segregation was present. The copolymers were studied with regard to their processing, miscibility, and mechanical properties. The first comparison with commercial formulations made with PVC and dioctyl phthalate (DOP) is presented. J. VINYL ADDIT. TECHNOL., 12:156–165, 2006. © 2006 Society of Plastics Engineers
HydroKorea and CarboKorea: cross‐scale studies of ecohydrology and biogeochemistry in a heterogeneous and complex forest catchment of Korea
Authors: Kim Joon , Lee Dongho , Hong Jinkyu , Kang Sinkyu , Kim Su‐Jin , Moon Sang‐Ki , Lim Jong‐Hwan , Son Yowhan , Lee Jaeseok , Kim Sanghyun , Woo Namchil , Kim Kyongha , Lee Buyong , Lee Byong‐Lyol , Kim Sung
Published: November 2006

The KoFlux program is dedicated to understanding the fluxes of energy and matter, water resource management, and net ecosystem production in key ecosystems of Monsoon Asia. Under the framework of AsiaFlux, it is a joint effort with determined, comprehensive international strategies to bring Asia's key ecosystems under observation. Built upon the augmented KoFlux infrastructure (i.e., Gwangneung supersite), the ‘HydroKorea’ and ‘CarboKorea’ projects pursue new methodologies to assess water and carbon cycles at various temporal, spatial, and process scales. Particularly, the multiscaling approaches are used to link process‐level studies, flux footprint, ecohydrological and biogeochemical schemes, and high‐resolution satellite images. We hope that the work presented here encourages more ground‐breaking studies aimed at bridging the gaps in the cross‐scale studies of ecohydrological and biogeochemical cycles in heterogeneous and complex landscapes.
Red tides in the Gulf of Mexico: Where, when, and why?
Authors: Walsh J. J. , Jolliff J. K. , Darrow B. P. , Lenes J. M. , Milroy S. P. , Remsen A. , Dieterle D. A. , Carder K. L. , Chen F. R. , Vargo G. A. , Weisberg R. H. , Fanning K. A. , Muller‐Karger F. E. , Shinn E. , Steidinger K. A. , Heil C. A. , Tomas C. R. , Prospero J. S. , Lee T. N. , Kirkpatrick G. J. , Whitledge T. E. , Stockwell D. A. , Villareal T. A. , Jochens A. E. , Bontempi P. S.
Published: November 2006

Independent data from the Gulf of Mexico are used to develop and test the hypothesis that the same sequence of physical and ecological events each year allows the toxic dinoflagellateKarenia brevisto become dominant. A phosphorus‐rich nutrient supply initiates phytoplankton succession, once deposition events of Saharan iron‐rich dust allowTrichodesmiumblooms to utilize ubiquitous dissolved nitrogen gas within otherwise nitrogen‐poor sea water. They and the co‐occurringK. brevisare positioned within the bottom Ekman layers, as a consequence of their similar diel vertical migration patterns on the middle shelf. Upon onshore upwelling of these near‐bottom seed populations to CDOM‐rich surface waters of coastal regions, light‐inhibition of the small red tide of ∼1 ug chl l−1of ichthytoxicK. brevisis alleviated. Thence, dead fish serve as a supplementary nutrient source, yielding large, self‐shaded red tides of ∼10 ug chl l−1.The source of phosphorus is mainly of fossil origin off west Florida, where past nutrient additions from the eutrophied Lake Okeechobee had minimal impact. In contrast, the P‐sources are of mainly anthropogenic origin off Texas, since both the nutrient loadings of Mississippi River and the spatial extent of the downstream red tides have increased over the last 100 years. During the past century and particularly within the last decade, previously crypticKarenia spp. have caused toxic red tides in similar coastal habitats of other western boundary currents off Japan, China, New Zealand, Australia, and South Africa, downstream of the Gobi, Simpson, Great Western, and Kalahari Deserts, in a global response to both desertification and eutrophication.
Factors affecting the accuracy of thermal imaging cameras in volcanology
Authors: Ball M. , Pinkerton H.
Published: November 2006

Volcano observatories and researchers are recognizing the potential usefulness of thermal imaging cameras both before and during volcanic eruptions. Obvious applications include measurements of the surface temperatures of active lava domes and lava flows to determine the location of the most active parts of these potentially hazardous features. If appropriate precautions are taken, the new generation of thermal imaging cameras can be used to extract quantitative as well as qualitative information on volcanic activity. For example, they can be used to measure the temperature of lava on eruption and to reveal how the crust cools during flow emplacement. This is important for the validation of lava flow models. To ensure that meaningful temperatures are collected, thermal imaging data must be corrected for instrumental errors, emissivity of the surface being imaged, atmospheric attenuation, viewing angle and surface roughness. Controlled laboratory experiments have been undertaken to determine the emissivity of smooth and rough samples and the effects of viewing angle and to quantify the errors. Measured emissivities range from 0.973 ± 0.002 for smooth samples of basalt and 0.984 ± 0.004 for rough samples. Errors in emissivity‐corrected temperatures are within ±15°C for lava at 1100°C. Variations from individual sensor receptors, which provide individual pixel temperature data, were found to be 0.6% and instrumental errors of the cameras used were 0.1%. Apparent temperatures were found to vary by less than the instrumental error for viewing angles up to 30 degrees from normal to lava, and thereafter increased by ∼1°C per degree. By increasing the apparent viewing distance of a small vent on Mount Etna from 1.5 to 30 m, the maximum temperature is shown to decrease by 53°C due to integrated averaging of radiance over increased pixel areas. At a viewing distance of 250 m the maximum temperature decreased by ∼200°C with a further 75°C decrease due to atmospheric attenuation for a relative humidity of 50%. However, errors in relative humidity measurements can lead to atmospheric attenuation correction inaccuracies up to 200°C at viewing distances of 1 km. We show how temperatures measured using thermal imaging cameras can be corrected to give improved estimates of temperature distributions on the surface of active lava flows.
Finite dispersal of a separative nepheloid plume by an internal hydraulic jump in a tropical mountainous river estuary
Authors: Wu Jiaxue , Ametistova Lioudmila , Heron Malcolm , Lemckert Charles J. , Kalangi Patrice
Published: November 2006

This paper investigates the dynamics of an internal hydraulic jump in a river plume and associated suspended sediment dispersal. Field investigations were undertaken into the river plume generated by the Herbert River, Australia, following a moderate flood event induced by Cyclone Fritz in 2004. The forced plume experiences an abrupt transition from supercritical to subcritical via an internal hydraulic jump, as defined by a mode‐1 internal Froude number computed using the phase speeds from the Taylor‐Goldstein equation. The hydraulic theory of a two‐layer stratified flow was used to identify the plume shape and the mechanical energy loss within the jump. The hydraulic jump energy loss is primarily transferred to the buoyancy‐driven potential energy, uplifting the river plume. Intense stratification decreases the bottom stress, damping the resuspension. Therefore, a separative nepheloid dispersal system occurs at the jump section. Both the upper and lower nepheloid flows are confined to the inner shelf, but have different dispersal behaviors and mechanisms. The upper nepheloid flow, which is primarily controlled by advection and settling, satisfies an exponential decay law of the total suspended sediment concentrations versus the offshore distance. The lower nepheloid flow dominated by deposition is detached seaward near the lift‐off point of the river plume. A turbidity front associated with the jump may accumulate a large quantity of suspended sediments, enhancing sediment release from the river plume. These findings will promote in‐depth understanding of both the cross‐shelf sediment dispersal and muddy deposit on the shelf.
Experimentally derived high‐pressure cumulates from hydrous arc magmas and consequences for the seismic velocity structure of lower arc crust
Authors: Müntener Othmar , Ulmer Peter
Published: November 2006

This contribution explores the consequences of experimentally derived ultramafic plutonic rocks for estimates of continental crust composition. The formation of high‐pressure cumulates from primitive to evolved hydrous arc magmas was investigated in the range 0.8–1.5 GPa and 1350–800°C, to provide constraints on solid assemblages that form the roots of island arc crust. At pressures exceeding 0.8 GPa (25km), 40–60% of ultramafic cumulates are produced to obtain andesite to dacite compositions that are typical for evolved island‐arc volcanic and plutonic rocks. Calculated cumulate densities are comparable or higher than upper mantle values, while seismic velocities (vp) vary continuously between 7.3 and 8 km/s, resulting in a broad crust‐mantle transition. The Moho represents a plagioclase saturation boundary. Our results are consistent with seismic imaging from continental margins and island arcs, revealing that beneath an active volcanic front a sharp geophysical Moho signature is sometimes absent.
Effect of the flow state on streaming current
Authors: Kuwano Osamu , Nakatani Masao , Yoshida Shingo
Published: November 2006

When a fluid flows through a porous medium, charges in the electric double layer are transported, resulting in a streaming current. This is the representative mechanism of self‐potential widely observed in the field. In the conventional Helmholtz‐Smoluchowski relation, the streaming current density (is) is represented as is = Ccgrad Pp, where Cc is the streaming current coefficient and Pp is the fluid pressure. Cc depends on the hydraulic property of the rock and the electrochemical property called the zeta potential. It was shown that the streaming current coefficient was clearly affected by the flow state: it was constant at a low Reynolds number Re, but decreased at Re > 1–10. This is a mechanical effect (i.e., smaller apparent permeability for nonlinear laminar flow), not a chemical effect on the zeta potential. The mutually contradicting values of zeta potential, which is calculated from measured Cc, obtained in different studies may be due to this effect. In addition, we found that the decreasing rate of Cc with increasing Re is much less than that of permeability. This means that nonlinear laminar flow induces more streaming current per unit flow rate.
Freshwater discharges in a simulation of the Last Glacial Maximum climate using improved river routing
Authors: Alkama R. , Kageyama M. , Ramstein G.
Published: November 2006

The large ice‐sheets over North America and Europe at the Last Glacial Maximum (LGM) strongly disturbed river pathways. This has never been taken into account in simulations of the LGM climate, even if it could have an impact on the freshwater input to the ocean. Here, we have introduced a more realistic river routing in LGM atmospheric general circulation model simulations. A comparison with classical LGM simulations shows that the discharge into the Arctic Ocean is not drastically different. Even if the Ob and Yenisei rivers could not reach the Arctic Ocean because of the Fennoscandian ice sheet (which results in a lake South of this ice sheet), the discharge of other rivers nearby is increased due to the influence of this lake. The maximum monthly discharge into the North Atlantic Ocean decreases by 34000 m3/s between 54 and 66°N, while it is stronger by 35000 m3/s between 28 and 54°N.
Angular variation of the magnetic properties and reversal mode of aligned single‐domain iron nanoparticles
Authors: Milne Glenn A. , Dunlop David J.
Published: November 2006

We report magnetic hysteresis and back‐field demagnetization data measured at 10° intervals of the angle ψ between the applied field H and the long (magnetically easy) axes of aligned elongated single‐domain iron particles electrodeposited in regularly spaced surface pores in an Al substrate. Our three samples have identical particle diameters, d = 17 nm, but varying axial ratios l/d and spacings dc. Measured hysteresis loops resemble “hysterons” predicted by fanning, curling, and coherent rotation models of magnetization reversal, except for two features. For ψ = 0–60°, particle magnetizations do not reverse simultaneously at a single critical field: distributed particle coercivities produce steep but nonvertical loop segments. Broadened ψ = 80–90° loops indicate imperfectly aligned particles. Comparing coercive force Hc(ψ) with theoretical variations for different angular dispersions of axes and Mrs/Ms data with a theoretical cos ψ variation, we find a variance of 6–8.5° in particle alignment. The Hc(ψ) results most closely resemble the theoretical variation for fanning rotations when ψ ≤ 50° and coherent rotations when ψ > 50°. A predicted hump in the Hc(ψ) curve at intermediate angles marking the changeover from one mechanism to the other is suppressed by particle interactions (packing factors p of 0.127–0.373). Remanent coercive force measurements Hcr(ψ) show that irreversible changes, unlike reversible rotations, are incoherent at both large and small ψ. Hcr continues to rise, to a high of 340–430 mT, as ψ → 90°, whereas Hc(ψ) decreases over the same range. Hcr(ψ) results at large ψ favor fanning reversals for one sample and curling reversals for the other two. A Day plot of Mrs/Ms versus Hcr/Hc data gives a novel and distinctive trend from which ψ can determined within ±5° for aligned uniaxial particles.
No proarrhythmic properties of the antibiotics Moxifloxacin or Azithromycin in anaesthetized dogs with chronic‐AV block
Authors: Thomsen M B , Beekman J D M , Attevelt N J M , Takahara A , Sugiyama A , Chiba K , Vos M A
Published: November 2006

Background & purpose:

The therapeutically available quinolone antibiotic moxifloxacin has been used as a positive control for prolonging the QT interval in both clinical and non‐clinical studies designed to assess the potential of new drugs to delay cardiac repolarization. Despite moxifloxacin prolonging QT, it has not been shown to cause torsades de pointes arrhythmias (TdP). Azithromycin is a macrolide antibiotic that has rarely been associated, clinically, with cases of proarrhythmia. As there is a lack of clinical data available, the cardiac safety of these drugs was assessed in a TdP‐susceptible animal model by evaluating their repolarization and proarrhythmia effects.

Experimental approach & Key results:

In transfected HEK cells, the IC50s forIhERGwere 45±6 and 856±259 μg ml‐1for moxifloxacin and azithromycin, respectively. Intravenous administration of 2 and 8 mg kg‐1moxifloxacin (total peak‐plasma concentrations 4.6±1.5 and 22.9±6.8 μg ml‐1) prolonged the QTcin 6 anaesthetized dogs with chronic AV block by 7±3 and 21±19%, respectively. Similar intravenous doses of azithromycin (total peak‐plasma concentrations 5.4±1.3 and 20.8±4.9 μg ml‐1) had no electrophysiological effects in the same dogs. The reference compound, dofetilide (25 μg kg‐1i.v.) caused QTcprolongation (29±15%) and TdP in all dogs. Beat‐to‐beat variability of repolarization (BVR), quantified as short‐term variability of the left ventricular monophasic action potential duration, was only increased after dofetilide (1.8±0.7 to 3.8±1.5 ms;P<0.05).

Conclusion & implications:

As neither moxifloxacin nor azithromycin caused TdP or an increase in the BVR, we conclude that both drugs can be used safely in clinical situations.

British Journal of Pharmacology(2006)149, 1039–1048. doi:10.1038/sj.bjp.0706900