bluuebunny/crossref_metadata_2025 huggingface dataset:
Health‐care providers' compliance with childhood acute lymphoblastic leukemia protocol in Indonesia
Authors: Sitaresmi Mei Neni , Mostert Saskia , Gundy Chad M. , Sutaryo  , Veerman Anjo J.P.
Published: September 2008

Background

Non‐compliance with childhood acute lymphoblastic leukemia (ALL) protocol is an important determinant of poor treatment outcome. Non‐compliance with protocol may not only concern parents or patients, but may also concern health‐care providers (HCP). Our study examines the accuracy of leukemia risk classification and attitude of HCP toward protocol compliance in Indonesia.

Procedure

A combined retrospective study of medical records (MR) and a cross‐sectional questionnaire study with HCP were conducted. Accurate ALL risk classification in MR was assessed. HCP' knowledge of risk classification and their attitude toward protocol compliance were examined.

Results

A total of 164 MR patients with ALL were assessed and 97 HCP were interviewed. The protocol criteria for high‐risk (HR) were not complete in 82 MR (50%). Of 97 HCP, 95% did not mention all five protocol criteria for HR. Both in the MR as well as in the questionnaires lymphoblast count on day 8 of chemotherapy, as early response to treatment, was the most frequently missed item (missing in 35% of MR and 85% of questionnaires). Only 14% of respondents actually checked with parents whether they administered the prescribed medicines.

Conclusions

Our study shows that HCP should improve their knowledge and assessment of childhood ALL risk classification, especially lymphoblast count on day 8 of chemotherapy. Proper risk classification and subsequent correct treatment may enable more children to be cured of leukemia. Pediatr Blood Cancer 2008;51:732–736. © 2008 Wiley‐Liss, Inc.
Progressive cracking mastercurves of the transverse ply in a laminate
Authors: Andersons J. , Joffe R. , Spārniņš E. , Rubenis O.
Published: September 2008

In this study, progressive cracking of a transverse layer in a cross‐ply composite laminate subjected to tensile loading is considered. Using the results of a probabilistic cracking model, approximate relations for crack density as a function of stress are derived for initiation‐controlled and propagation‐controlled cracking. It is shown that the crack density evolution in the transverse ply can be represented by a mastercurve in suitably normalized coordinates. The mastercurve approach is applied to progressive cracking in glass/epoxy laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Artificial intelligence techniques in simulation of viscoplasticity of polymeric composites
Authors: Al‐Haik M.S. , Hussaini M.Y. , Rogan C.S.
Published: September 2008

The viscoplastic behavior of a carbon fiber/polymer matrix composite is investigated via different modeling schemes. The first model is phenomenological in nature based on the overstress‐viscoplasticity. The second model utilizes neural networks paradigms. Genetic algorithm‐based strategies are used to prune the proposed neural network. Several optimization algorithms are implemented for training the network. In comparison, the neurocomputational model is found to outperform the phenomenological model. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Enhanced degradation of poly(L‐lactide) containing arginine, tryptophan and lysine
Authors: Zhao Na , Xiong Zuochun , Yang Dejuan , Xu Liang , Bai Wei , Xiong Chengdong
Published: September 2008

Addition of arginine, tryptophan and lysine to poly(L‐lactide) (PLLA) has resulted in a new series of enhanced degradation biomaterials. Degradation was performed at 70°C and degradation behavior was studied using water uptake, mass loss, pH value change, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile properties. The results indicated that PLLA containing amino acids degraded more quickly than pure PLLA. In PLLA containing arginine, lysine, or tryptophan, crystallinity of the latter decreased after 8 days degradation while crystallinities of the other two composites increased. Destroying crystallites assists with deeper degradation and in vivo assimilation. Initial tensile strengths of all undegraded bars were almost the same. Furthermore, pH value changes indicated that additive amino acids could neutralize acidic degradation products, which may be a solution to the bacteria‐free inflammation induced by the acidic products. The results indicate that the composite biomaterials may be useful for future clinical application. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
A facile preparation of composites composed of cellulose and polymeric ionic liquids by in situ polymerization of ionic liquids having acrylate groups
Authors: Takegawa Akihiko , Murakami Masa‐aki , Kaneko Yoshiro , Kadokawa Jun‐ichi
Published: September 2008

In this study, a facile preparation of the composites composed of cellulose and the polyacrylate‐type polymeric ionic liquids was carried out by the in situ polymerization of the polymerizable ionic liquids. The two polymerizable ionic liquids were employed, which had one polymerizable group (acrylate) and two polymerizable groups (acrylate and vinyl). First, the pretreatment of cellulose in the mixtures of the two ionic liquids were performed, resulting in disrupting most crystalline structure of cellulose. Then, the radical polymerization of the ionic liquids in the pretreated mixtures was carried out by AIBN to obtain the composites. The analytical data of the composites indicated the good compatibility between cellulose and the polymeric ionic liquids. Furthermore, the mechanical properties of the composites were measured by a tensile tester. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Nanostructured polyaniline reinforced sustainable resource (soy oil alkyd) based composites
Authors: Alam Javed , Riaz Ufana , Ahmad Sharif
Published: September 2008

Studies on composites and blends based on nanostructured polyaniline (PANI) have become the subject of scientific curiosity with regard to their morphology, stability, and electronic properties. Nanocomposites of conducting polymers display improved mechanical, electrical, optical, and catalytic properties owing to their remarkable nanostructure. The present study reports the synthesis of nanostructured PANI and its composites based on soy oil alkyd. The effect of loading of nanostructured PANI on the physiochemical, physicomechanical, morphological, and thermal properties of the composite has been analyzed. POLYM. COMPOS., 2010. © 2008 Society of Plastics Engineers
Visualization study of foaming process for polyimide foams and its reinforced foams
Authors: Pan Ling‐Ying , Shen Yan‐Xia , Zhan Mao‐Sheng , Wang Kai , Gao Da‐Li
Published: September 2008

In this article, the foaming processes of polyimide foams and its reinforced foams were observed by a self‐made visualization device at different heating rates ranging from 10°C/min to 120°C/min. Contributing factors such as chemical structure of polyimide, fillers, and heating rate were investigated to determine the effects on the inflation onset temperature and morphological change of polyimide foam precursor powders. The results showed that the powder might grow into a single bubble mesostructure at a lower heating rate or a multibubble mesostructure at a higher heating rate. Because of the filling of reinforcing fillers, the inflation morphology of reinforced polyimide foam precursor powders show a different change trend with the increase of temperature compared to the pure polyimide foam precursor powders. For all kinds of polyimide foam precursor powders investigated in this article, the inflation morphologies showed a similar variation trend with different heating rates, and the final inflation degrees were slightly different. The inflation onset temperatures of all polyimide foam precursor powders studied decreased with increasing heating rate. POLYM. COMPOS., 2010. © 2008 Society of Plastics Engineers
Medicine utilisation review in selected non‐governmental organisations primary healthcare clinics in the West Bank in Palestine
Authors: Khatib R. , Daoud A. , Abu‐Rmeileh N.M.E. , Mataria A. , McCaig D.
Published: September 2008

Background

Information on prescribing practices in Palestine is lacking, however, still essential for strategic planning.

Purpose

To characterise prescribing patterns and specific medicine use indicators in selected non‐governmental organisations' (NGO) primary healthcare clinics/centres (PHC) in the West Bank (WB) in Palestine.

Methodology

A prospective cross‐sectional survey of prescribing practices based on medical records of 6032 patients with acute symptoms frequenting 41 NGO PHCs in the WB, between July and September 2004. A systematic random sample of every 10th patient appearing on the patient registration list was selected. Direct observation of consultation and dispensing practices and times in a sub‐group of patients was completed utilising special forms.

Results

Respiratory tract infections were the most commonly occurring conditions. On average, 1.9 drugs were prescribed per encounter and antibiotics were the most commonly prescribed medications, followed by Analgesics and NSAIDs accounting for 46 and 20% of the total medications expenditures, respectively. Injections and combined medications use per encounter was 16 and 8%, respectively. Most commonly prescribed medications were of local production. Consultation (6.4 ± 4.6 minutes) and dispensing times (1.6 ± 1.5 minutes) were short with inadequate labelling. Provision of reference sources and treatment guidelines implementation were also inadequate.

Conclusion

The results suggest that prescribing practices could be improved through wider implementation of treatment guidelines, a review of antibiotic prescribing, and increased time spent with patients to promote concordance. Strategies aimed at improving prescribing and dispensing practices should be addressed through new innovative capacity building models based on problem solving and feedback mechanisms. Copyright © 2008 John Wiley & Sons, Ltd.
Reactions of 1,2,5‐thiadiazole 1,1‐dioxide derivatives with nitrogen nucleophiles. Part IV. Addition of α‐diamines
Authors: Mirífico María Virginia , Caram José Alberto , Vasini Enrique Julio , Piro Oscar Enrique , Castellano Eduardo E.
Published: September 2008

α‐diamines, such as ethylendiamine and o‐phenylendiamine, add to 3,4‐aryl‐disubstituted 1,2,5‐thiadiazole 1,1‐dioxides to give dihydropyrazines or quinoxalines, respectively and sulfamide. The new compound acenaphtho [5,6‐b]‐2,3‐dihydropyrazine was synthesized and characterized. The addition of ethylendiamine to 3,4‐diphenyl‐ 1,2,5‐thiadiazoline 1,1‐dioxide gives 3,4‐disubstituted thiadiazolidine 1,1‐dioxide, dihydropyrazines, or pyrazines, depending on the reaction condition used. The reactions were followed by cyclic voltammetry and NMR spectroscopy which, in some cases, allowed the detection of the thiadiazolidine intermediate. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis of amphiphilic multiblock and triblock copolymers of polydimethylsiloxane and poly(N,N‐dimethylacrylamide)
Authors: Pavlović Dražen , Linhardt Jeffrey G. , Künzler Jay F. , Shipp Devon A.
Published: September 2008

The synthesis and spectroscopic characterization of a new family of amphiphilic multiblock and triblock copolymers is described. The synthetic methodology rests on the preparation of telechelic multifunctional and difunctional chain transfer agents easily available in two synthetic steps from commercially available polydimethylsiloxane‐containing starting materials. Telechelic polymers thus synthesized are used as macromolecular chain transfer agents in the reversible addition fragmentation chain transfer (RAFT) polymerization of N,N‐dimethylacrylamide (DMA) enabling the synthesis of (AB)n‐type multiblock and ABA‐type triblock copolymers of varying compositions possessing monomodal molecular weight distribution. (AB)n multiblock copolymers [(PDMA‐b‐PDMS)n] were prepared with between 52 and 95 wt % poly(dimethylacrylamide) with number average molecular weights (Mn) between 14,000 and 86,000 (polydispersities of 1.20–2.30). On the other hand, ABA block copolymers with DMA led to amphiphilic block copolymers (PDMA‐b‐PDMS‐b‐PDMA) with Mn values between 9000 and 44,000 (polydispersities of 1.24–1.62). © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7033–7048, 2008
Recent advances in controlled/living radical polymerization in emulsion and dispersion
Authors: Oh Jung Kwon
Published: September 2008

Effective ways to conduct controlled/living radical polymerization (CRP) in emulsion systems are necessary for commercial latex production without significant modification of current industrial facilities. Conducting CRP in emulsion media is more complicated and more challenging than its application in homogeneous bulk. These challenges come from the intrinsic kinetics of emulsion polymerization. They include mass transport, slow chain growth mechanism, and exit of short radicals from polymeric particles. This review describes the recent developments of CRP in heterogeneous dispersion, including miniemulsion, microemulsion, dispersion, and especially emulsion. Various approaches for conducting emulsion CRP are detailed, including controlled seeded emulsion polymerization, nanoprecipitation, use of short oligomers as macroinitiators for in situ block copolymerization, and RAFT‐mediated self‐assembly. In addition many remaining challenges of the current methods barring wide spread industrial application of emulsion CRP are also suggested. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6983–7001, 2008
Ethylene polymerization of the new titanium complexes bearing a phosphine oxide‐bridged bisphenolato ligand
Authors: He Li‐Peng , Liu Jing‐Yu , Pan Li , Li Yue‐Sheng
Published: September 2008

A series of novel titanium(IV) complexes combining a phosphine oxide‐bridged bisphenolato ligand TiCl2{2,2′‐OP‐R3 (4‐R2‐6‐R1‐C6H2O)2}(THF) (6a: R1 = tBu, R2 = H, R3 = Ph; 6b: R1 = Ph, R2 = H, R3 = Ph; 6c: R1 = R2 = tBu, R3 = Ph; 6d: R1 = R2 = cumyl, R3 = Ph; 6e: R1 = tBu, R2 = H, R3 = PhF5) were prepared by the reaction of corresponding bisphenolato ligands with TiCl4 in THF. X‐ray analysis reveals that complex 6a adopts distorted octahedral geometry around the titanium center. These catalysts were performed for ethylene polymerization in the presence of modified methyaluminoxane (MMAO). The effects of reaction parameters on ethylene polymerization behaviors, such as cocatalyst concentration, polymerization temperature, and reaction time were studied in detail. In general, these new complexes exhibited high catalytic activity, good temperature tolerance, and long lifetime for ethylene polymerization. The resulting polymers possess high molecular weight, unimodal distribution, and linear structure. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7062–7073, 2008
High temperature resistant tailor‐made poly(meth)acrylates bearing adamantyl group via atom transfer radical polymerization
Authors: Kavitha A. Amalin , Singha Nikhil K.
Published: September 2008

This investigation reports preparation of tailor‐made poly(meth)acrylates bearing adamantyl group using atom transfer radical homo and copolymerization via initiator as well as via monomer approach. The ATRP of methyl methacrylate was investigated using different initiators having adamantyl group (like AdMBr or AdBr) as well as conventional EBiB initiator and CuBr as catalyst in combination with PMDETA as ligand. It was observed that the incorporation of the bulky adamantyl group increased the rate of polymerization. The polymerization proceeded through first‐order kinetics and molecular weights increased linearly with conversion, close to the targeted molecular weights. The living nature of the end‐group was confirmed by MALDI‐TOF‐mass spectrometry and chain extension experiment. The homopolymerization of adamantyl methyl acrylate (AdMA) and its copolymerization with MA was successfully carried out using methylbromopropionate (MBrP) as initiator and CuBr/dNbpy as the catalyst. Interestingly, the resultant poly(meth)acrylates bearing the adamantyl group had excellent thermal stability and much better thermal stability than the similar polymers without adamantyl group as evidenced from thermogravimetry analysis (TGA) and isothermal TGA studies. Importantly, incorporation of adamantyl group “adamantly” increases rate of polymerization, thermal stability, and glass transition temperature of the polymers. All the polymers were characterized by NMR, MALDI‐TOF‐MS, DSC, and TGA analysis. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7101–7113, 2008
Molecular design of outermost surface functionalized thermoresponsive polymeric micelles with biodegradable cores
Authors: Akimoto Jun , Nakayama Masamichi , Sakai Kiyotaka , Okano Teruo
Published: September 2008

We prepared well‐defined diblock copolymers of thermoresponsive poly(N‐isopropylacrylamide‐co‐N,N‐dimethylacrylamide) blocks and biodegradable poly(D,L‐lactide) blocks by combination of reversible addition‐fragmentation chain transfer radical (RAFT) polymerization and ring‐opening polymerization. α‐Hydroxyl, ω‐dithiobenzoate thermoresponsive polymers were synthesized by RAFT polymerization using hydroxyl RAFT agents. Biodegradable blocks were prepared by ring‐opening polymerization of D,L‐lactide initiated by α‐hydroxyl groups of thermoresponsive polymers, which inhibit the thermal decomposition of ω‐dithioester groups. Terminal dithiobenzoate (DTBz) groups of thermoresponsive blocks were easily reduced to thiol groups and reacted with maleimide (Mal). In aqueous media, diblock copolymer products formed surface‐functionalized thermoresponsive micelles. These polymeric micelles had a low critical micelle concentration of 22 μg/L. In thermoresponsive studies of the micelles, hydrophobic DTBz‐surface micelles demonstrated a significant shift in lower critical solution temperature (LCST) to a lower temperature of 30.7 °C than that for Mal‐surface micelles (40.0 °C). In addition, micellar LCST was controlled by changing bulk mixture ratios of respective heterogeneous end‐functional diblock copolymers. Micellar disruption at acidic condition (pH 5.0) was completed within 5 days due to hydrolytic degradation of PLA cores, regardless of showing a slow disruption rate at physiological condition. Furthermore, we successfully improved water‐solubility of hydrophobic drug, paclitaxel by incorporating into the micellar cores. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7127–7137, 2008
Libraries of methacrylic acid and oligo(ethylene glycol) methacrylate copolymers with LCST behavior
Authors: Becer C. Remzi , Hahn Sabine , Fijten Martin W. M. , Thijs Hanneke M. L. , Hoogenboom Richard , Schubert Ulrich S.
Published: September 2008

Homopolymers of methacrylic acid (MAA), monoethyleneglycol methyl ether methacrylate (MEOMA), diethyleneglycol methyl ether methacrylate (MEO2MA), oligo(ethyleneglycol) methyl ether methacrylate (OEGMA475 and OEGMA1100) and oligo(ethyleneglycol) ethyl ether methacrylate (OEGEMA246) were synthesized with various chain lengths via reversible addition fragmentation chain transfer (RAFT) polymerization. The homopolymers of MAA, MEOMA and OEGMA1100 did not show any cloud point (CP) in the range of 0–100 °C, whereas at a pH value of 7, the CPs were found to be 20.6, 93.7, and 20.0 °C for p(MEO2MA), p(OEGMA475) and p(OEGEMA246), respectively, with an initial monomer to initiator ratio of 50. Furthermore, statistical copolymer libraries of MAA with OEGMA475 and OEGMA1100 were prepared. The cloud points of the random copolymers of MAA and OEGMA475 were found to be in the range of 20–90 °C; surprisingly, even though the homopolymers of MAA and OEGMA1100 did not exhibit any LCST behavior, the copolymers of these monomers at certain molar ratios (up to 40% OEGMA1100) revealed a double responsive behavior for both temperature and pH. Finally, the cloud points were found to be in the range of 22–98 °C, measured at pH values of 2, 4, and 7, while no cloud point was detected at pH 10. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7138–7147, 2008
Novel biomarkers for risk of prostate cancer: Results from a case–control study
Authors: Yang Li , Gaikwad Nilesh W. , Meza Jane , Cavalieri Ercole L. , Muti Paola , Trock Bruce , Rogan Eleanor G.
Published: September 2008

BACKGROUND

Although the estrogens estrone and estradiol are recognized to play very important roles in the risk of developing prostate cancer (Pca), the molecular mechanism by which estrogens initiate and/or promote Pca is still unknown. Substantial evidence supports that specific metabolites of estrogens, catechol estrogen quinones, can react with DNA to form depurinating estrogen‐DNA adducts. Apurinic sites derived from depurination of these adducts can induce mutations leading to cancer. Once released from DNA, depurinating estrogen‐DNA adducts are shed from cells into the bloodstream and excreted in urine. By analyzing profiles of estrogen metabolites, conjugates, and depurinating DNA adducts in urine from men with and without prostate cancer, potential biomarkers of Pca can be detected. The goal of this case–control study was to detect and identify potential biomarkers of Pca.

METHODS

Urine samples from fourteen cases, men diagnosed with Pca, and 125 controls, men who had not been diagnosed with Pca, were partially purified by solid phase extraction and analyzed by ultraperformance liquid chromatography/tandem mass spectrometry. The urinary levels of androgens, estrogens, estrogen metabolites, conjugates and depurinating DNA adducts were measured.

RESULTS

The ratio of depurinating estrogen‐DNA adducts to the sum of the corresponding estrogen metabolites and conjugates was significantly higher in cases (median: 57.34) compared to controls (median: 23.39) (P < 0.001).

CONCLUSIONS

This study suggests that depurinating estrogen‐DNA adducts could serve as potential biomarkers to predict risk of Pca. They also could be useful tools for early clinical diagnosis and development of suitable strategies to prevent Pca. Prostate 69: 41–48, 2009. © 2008 Wiley–Liss, Inc.
Computational studies on the backbone‐dependent side‐chain orientation induced by the (S,S)‐CXC motif
Authors: Stavrakoudis Athanassios , Tsikaris Vassilios
Published: September 2008

Disulfide cyclization is a well‐known procedure to impose conformational restriction to peptides undergoing backbone flexibility. Rigid conformations are induced only for small rings with a specific combination of amino acids. In this work, we present a computational search of the backbone and backbone‐dependent side‐chain orientation of two series of linear and cyclic peptide analogs. The ‐C[XY]C‐ scaffold (where X,Y is arginine, aspartic acid or alanine residue) in its open and (S,S) cyclic form was used for the design of the studied analogs. Thirty‐six compounds, resulting from the extension with one residue at either the N‐ or the C‐terminus were studied with classical MD. The local backbone conformation and the relative orientation of the X and Y side chains induced by either cyclization and/or the presence of the charged residues are discussed. From the present study it is concluded that cyclization has a great impact on the synplanar orientation of the X and Y side chains in the (S,S)Ac‐XCYC‐NH2 series of compounds while charge–charge interaction has only a weak synergic effect. On the contrary, the antiplanar orientation is favored in the case of (S,S)Ac‐CXCY‐NH2. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Evaluating the coupling efficiency of phosphorylated amino acids for SPOT synthesis
Authors: Tapia Victor , Ay Bernhard , Triebus Julia , Wolter Eike , Boisguerin Prisca , Volkmer Rudolf
Published: September 2008

A high demand of interest concerning binding assays to study the consequences of posttranscriptional phosphorylation may be addressed by peptide array‐based methods. A crucial factor forde novochemical approaches to generate such arrays is the possibility to rationally permutate phosphorylation events along a huge number of sequences. The simple principle behind this advantage is the stepwise synthesis of peptides, which allows the incorporation of either phosphorylated or nonphosphorylated derivates at serine, threonine, and tyrosine positions. In spite of several reported applications of phosphopeptide arrays, there is, to our best knowledge, no reported analysis of the efficiency of the involved techniques. Here, we analyze different coupling conditions to introduce phosphoamino acids in standard SPOT synthesis. Our results clearly indicate that EEDQ is the preferable activator and can also be used in fully automated SPOT synthesis. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Broadband electrical characterization of macroporous silicon at microwave frequencies
Authors: Contopanagos H. , Pagonis D. N. , Nassiopoulou A. G.
Published: September 2008

Macroporous silicon layers with randomly distributed vertical cylindrical pores of average diameter 120 nm were fabricated on selected areas on a p+ (resistivity 5 mΩcm) silicon substrate by anodization in HFxethanol solution. The thickness of the layers was 50 μm and they are intended for use as RF isolation micro‐plates for on‐chip passive devices operated at microwave frequencies. In this respect, we present in this work results of their electrical characterization in the 40 MHz‐7 GHz frequency range using a macroscopic platform, where the die containing the porous silicon layer on the highly doped Si substrate is inserted directly underneath a microstrip line. The highly doped Si substrate used acts as a lossy metal ground for the microstrip. We measured and simulated the scattering parameters of the system using a finite‐element full‐wave electromagnetic solver. We have chosen a broad frequency band extending from 40 MHz up to 7 GHz, beyond the first harmonic of the transmission line. By identifying measured and simulated S‐parameters over the whole frequency band we extract both geometrical characteristics of the measurement set‐up not accessible to direct measurements and the complex permittivity of porous silicon. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of processing parameters on the fabrication of auxetic extruded polypropylene films
Authors: Chirima G. , Ravirala N. , Rawal A. , Simkins V. R. , Alderson A. , Alderson K. L.
Published: September 2008

A processing parameter study for extruded polypropylene films has been carried out. Films were extruded at temperatures varying from 157 °C to 230 °C, screw speed from 0.525 rad s–1 to 2.10 rad s–1 and take up speed from 0.0225 m s–1 to 0.15 m s–1. Characterisation of the films was undertaken to determine Poisson's ratio, ν, using video exten‐ sometry and it was found that it was possible to vary the Poisson's ratio from positive (ν = +0.4) to negative (as low as ν = –1) by varying the processing parameters, allowing the possibility of tailoring the Poisson's ratio to specified applications driven values. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The ensemble Kalman filter in an operational regional NWP system: preliminary results with real observations
Authors: Bonavita Massimo , Torrisi Lucio , Marcucci Francesca
Published: September 2008

The ensemble Kalman filter (EnKF) has been widely tested as a possible candidate for the next generation of meteorological and oceanographic data assimilation algorithms. While a number of tests with models of varying realism have been successfully performed, the EnKF has been seldom evaluated in an operational regional NWP environment at realistic spatial resolution. In this work one particular EnKF implementation (Local Ensemble Transform Kalman Filter, LETKF) has been implemented and its performance evaluated in comparison with CNMCA operational 3D‐Var.

One of the most important issues in EnKF implementations lies in the filter tendency to become underdispersive for practical ensemble sizes. While multiplicative (or additive) covariance inflation has been used to deal with this problem, tuning its values is an expensive and possibly never‐ending task. Following ideas from linear estimation theory, we test an adaptive estimation procedure to evaluate forecast covariance inflation factors and observation errors. Our results show that, differently from previous experiences, the online estimation technique can be successfully employed in a realistic state‐of‐the‐art NWP system. More generally the LETKF analysis is shown to be of superior quality with respect to the operational 3D‐Var and a likely candidate for its replacement in the not‐too‐distant future. Copyright © 2008 Royal Meteorological Society
Sunny Greenland
Authors: Scorer R. S.
Published: September 2008

Greenland is about the same size as the plateau of Tibet. It is, by contrast, a cold source and a complete obstruction to the advance of air at sea level. Air flowing from the ice plateau originates at around plateau level. The general slope towards the north and west causes a katabatic land breeze on the west coast. The so‐called Iceland low in its movements from Cape Farewell more than half way to Spitzbergen causes a prevailing wind from the north or north‐east along the lee coast which drives ice as far as Cape Farewell all year round. The earth's rotation causes the ocean current to turn the cape and occasionally carry ice 100‐200 km up the west coast. But for most of the year the wind is from the north while the salty water moves from the south.

When cirrus moves inland it is not accompanied by air at sea level and when air descends from the plateau the flow at cirrus level is usually upslope so that a trail of orographic cirrus leaves the coast.

The Iceland low frequently carries warm air across the Faeroes and Jan Mayen to the east coast at Scoresbysund and even to the west of Iceland and at the same time draws arctic air from the Davis Strait across the Atlantic to Britain to form an inverted front on which a row of small cyclones forms.

The general picture formed from looking at about nine years of satellite pictures is that the weather goes on around Greenland and is steered by it, but only occasionally penetrates over the plateau and then neither far nor for long. While Spitzbergen, Iceland, and other territories around are some of the cloudiest places on earth, Greenland is a very sunny place, and yet it remains a very significant source of cold.
Airmass transformation over the South China Sea during a winter MONEX cold surge
Authors: Martin David W. , Reiff J. , Mower R. N.
Published: September 2008

Several studies have linked a wintertime cycle of deep, moist near‐equatorial convection to surges of cold air from Asia. According to an early hypothesis two successive streams of surge air reach north Borneo and offshore waters of the South China Sea. The first, which follows a long over‐water trajectory, is warm by the time it arrives off Borneo. The second, which follows a short over‐water trajectory, still is cool when it arrives off Borneo. More recent hypotheses suggest only the second stage of the surge involves an airstream from Asia and drying rather than cooling is the predominant downstream thermodynamic effect on this airstream.

By means of trajectory calculations and an airmass transformation (AMT) model we test these ideas for a moderate cold surge from December 1978. In particular, we contrast the roles, in the transformation process, of surface fluxes of latent and sensible heat and of boundary layer entrainment. At no time through the course of the surge did we find boundary layer trajectories of the second (short path) type. Nevertheless, late in the course of the case study surge dry air did appear at the surface off the south‐east coast of Vietnam. Neither sea surface temperature nor initial airmass structure could account for the local nature of the drying. The explanation most consistent both with observations and AMT model results is entrainment of air that had been dried by local subsidence at and above the top of the marine boundary layer.
Numerical studies of eddy transport properties in eddy‐resolving and parametrized models
Authors: Vallis G. K.
Published: September 2008

This paper is a study of the transport properties of large‐scale quasi‐geostrophic flow, when it is forced by an unstable shear of much greater horizontal scale than the scale of the resultant eddies. One of the purposes is thereby to test certain phenomenological parametrization schemes which predict the transport of potential vorticity or heat, or which predict the time‐mean state of the zonally averaged atmosphere. Models used are highly nonlinear spectral quasi‐geostrophic models, with sufficient resolution to resolve the energy‐containing scales and partially resolve an enstrophy inertial range. A scale separation is enforced between the mean and eddy flow, this being a necessary condition for transfer theories to work. An expression is derived for the rate of change of the mean flow in such cases. As a quantitative predictor of the time‐mean state of the zonal flow, baroclinic adjustment is found to work only when nonlinear wave‐wave interaction between eddies is small. In such cases, the amplitude of the eddy flow is determined by the forcing on the zonal flow, which itself equilibrates close to the critical value for linear instability. In fully nonlinear models if the zonal flow is strongly forced the mean flow can be highly supercritical. The flux of potential vorticity is found to depend strongly and monotonically on the mean shear, although no obvious simple relationship is found relating it to potential vorticity gradient. In part because potential vorticity is not a passive scalar, using phenomenological transfer coefficients is by no means straightforward. Such transfer relationships are seen to be in some ways unsatisfactory.
Variation of frontal and precipitation structure along a cold front
Authors: Browning K. A. , Roberts N. M.
Published: September 2008

A diagnostic study is presented to illustrate the sequence of events in which a warm‐conveyor‐belt (WCB) flow is drawn into the circulation of a developing extratropical cyclone and interacts with dry air aloft to produce distinctive precipitation structures. The poleward boundary of the upstream end of the WCB was associated with a classical (ana) cold‐frontal structure. The other end of the WCB flow, closer to the cyclone centre, was overrun by a ‘dry intrusion’ of low wet‐bulb potential temperature air to give a split (kata) cold front. The orientation of the surface cold front (i.e. the WCB boundary) changed significantly between these two parts but the orientation of the surface geostrophic flow within the WCB changed relatively little between the two parts. The surface cold front was characterized in most places by a narrow cold‐frontal rainband composed of shallow line‐convection elements (precipitation cores) aligned nearly parallel to the surface geostrophic flow in the WCB. The changing relationship between the frontal orientation and the direction of the surface flow accounts for the fact that the line‐convection elements occurred end‐to‐end to give almost two‐dimensional line convection along the classical ana part of the cold front, but were non‐aligned and widely spaced along the split cold‐front part.
Dimensional analysis of a convecting atmosphere in equilibrium with external forcing
Authors: Craig George C.
Published: September 2008

It has recently been suggested by Rennó and Ingersoll that certain properties of a convecting atmosphere in equilibrium with external forcing can be predicted by considering the convecting atmosphere as a heat engine. Their argument is modified to express the forcing of convection in terms of a specified cooling of the convective layer. It is found that convective available potential energy and mean convective vertical velocity are independent of the forcing, while the fractional area of the convection increases in proportion with the forcing. These predictions are consistent with recent numerical results from cloud‐ensemble models. Finally, it is shown by a formal dimensional analysis that these conclusions are independent of the details of the thermodynamic formulation.
The role of droplet spectra for cloud radiative properties
Authors: Hatzianastassiou Nikos , Wobrock Wolfram , Flossma Andrea I.
Published: September 2008

The evolution of different types of clouds is simulated with a spectral scavenging and microphysics model, DESCAM, coupled to the dynamics of an ascending and entraining air‐parcel model. the resulting microphysical properties of the cloud are then coupled with a radiative‐transfer model in order to calculate the optical properties, the up‐ and downgoing radiative fluxes, the cloud optical depth, and the cloud albedo. For a stratiform cloud investigated during the North Atlantic Regional Experiment good agreement with the experimental data is obtained. For a medium‐sized convective cloud developing in marine or continental air the calculated cloud optical depth and the cloud albedo are compared with current parametrizations in global circulation models. the largest deviations are observed for cases with a large effective radius, e.g. when the cloud developed precipitation. In general, cloud optical depth and cloud albedo per unit cloud depth decrease with time, caused by the broadening of the cloud‐drop spectrum.
Attribution and its application to mesoscale structure associated with tropopause folds
Authors: Thorpe A. J.
Published: September 2008

It is important in meteorology to be able to establish a link between various features. This link in its strongest form would be referred to as ‘cause‐and‐effect’ but this is extremely difficult to establish for atmospheric flows. A weaker, but nonetheless powerful, link is ‘attribution’ which attempts to provide a way to associate various fundamental features, such as potential‐vorticity anomalies, to weather events involving regions of ascent. Attribution is not new and it is implicit in the way that atmospheric evolution is usually described. In this paper an attempt is made to define more precisely what are the steps and assumptions being made in such a method. These ideas become more concrete by applying them to a simple model of a two‐dimensional front at which there is a tropopause fold. the aim is to find the vertical motion attributable to the descended tropopause fold in an extra‐tropical cyclone. This is the first step in a longer programme of research designed to provide a test of the hypothesis that such a descended tropopause can trigger mesoscale phenomena such as convection and cyclones.
Observer‐based control of block‐triangular discrete time hybrid automata on a partial order
Authors: Del Vecchio Domitilla
Published: September 2008

The safety control problem for the class of discrete time block‐triangular order preserving hybrid automata with imperfect continuous state information is addressed. A dynamic feedback law is constructed in order to guarantee that the continuous state is always outside a bad set. The order preserving properties of the dynamics are exploited to construct state estimation and control algorithms that have linear complexity in the number of variables. Such algorithms adopt an interval abstraction approach, in which sets of interest are represented and propagated only through suitable upper and lower bounds. The proposed algorithms are applied to a collision avoidance problem arising in the context of intelligent transportation. Copyright © 2008 John Wiley & Sons, Ltd.
Measures to assess the prognostic ability of the stratified Cox proportional hazards model
Authors:   The Fibrinogen Studies Collaboration
Published: September 2008

Many measures have been proposed to summarize the prognostic ability of the Cox proportional hazards (CPH) survival model, although none is universally accepted for general use. By contrast, little work has been done to summarize the prognostic ability of the stratified CPH model; such measures would be useful in analyses of individual participant data from multiple studies, data from multi‐centre studies, and in single study analysis where stratification is used to avoid making assumptions of proportional hazards. We have chosen three measures developed for the unstratified CPH model (Schemper and Henderson's 𝒱 , Harrell's C‐index and Royston and Sauerbrei's 𝒟), adapted them for use with the stratified CPH model and demonstrated how their values can be represented over time. Although each of these measures is promising in principle, we found the measure of explained variation 𝒱 very difficult to apply when data are combined from several studies with differing durations of participant follow‐up. The two other measures considered, 𝒟 and the C‐index, were more applicable under such circumstances. We illustrate the methods using individual participant data from several prospective epidemiological studies of chronic disease outcomes. Copyright © 2008 John Wiley & Sons, Ltd.
Joint analysis of multiple longitudinal outcomes: Application of a latent class model
Authors: Putter Hein , Vos Tineke , de Haes Hanneke , van Houwelingen Hans
Published: September 2008

We address the problem of joint analysis of more than one series of longitudinal measurements. The typical way of approaching this problem is as a joint mixed effects model for the two outcomes. Apart from the large number of parameters needed to specify such a model, perhaps the biggest drawback of this approach is the difficulty in interpreting the results of the model, particularly when the main interest is in the relation between the two longitudinal outcomes. Here we propose an alternative approach to this problem. We use a latent class joint model for the longitudinal outcomes in order to reduce the dimensionality of the problem. We then use a two‐stage estimation procedure to estimate the parameters in this model. In the first stage, the latent classes, their probabilities and the mean and covariance structure are estimated based on the longitudinal data of the first outcome. In the second stage, we study the relation between the latent classes and patient characteristics and the other outcome(s). We apply the method to data from 195 consecutive lung cancer patients in two outpatient clinics of lung diseases in The Hague, and we study the relation between denial and longitudinal health measures. Our approach clearly revealed an interesting phenomenon: although no difference between classes could be detected for objective measures of health, patients in classes representing higher levels of denial consistently scored significantly higher in subjective measures of health. Copyright © 2008 John Wiley & Sons, Ltd.
System dynamics as model‐based theory building
Authors: Schwaninger Markus , Grösser Stefan
Published: September 2008

This paper introduces model‐based theory building as a feature of system dynamics (SD) with large potential. It presents a systemic approach to actualizing that potential, thereby opening up a new perspective on theory building in the social sciences. The question addressed is if and how SD enables the construction of high‐quality theories. This contribution is based on field experiment type projects which have been focused on model‐based theory building, specifically the construction of a middle‐range theory—not a general one. The process of model building and validation is analysed from a theory‐building perspective. The resulting theory is evaluated by means of a set of criteria for high‐quality theories. As a conclusion, the insights thus gained are presented and condensed in a tentative set of heuristic principles for model‐based theory building. Copyright © 2008 John Wiley & Sons, Ltd.
System of system failures: Meta methodology for IT engineering safety
Authors: Nakamura Takafumi , Kijima Kyoich
Published: September 2008

A meta methodology for holistically examining system failures is proposed, for the purpose of preventing further occurrence of these failures. Such a meta methodology should promote double loop learning to change mental models. It should have three key features to promote double loop learning, and the proposed methodology provides them. These features are (1) a common language for understanding system failures, (2) complementary methodological features to accommodate multiple participants in achieving engineering safety and (3) inclusion of the dynamic aspects of system failures in order to avoid the introduction of side effects by quick fixes. An application example in IT engineering demonstrates that the proposed meta methodology overcomes the shortcomings of current methodologies. The example also shows that the meta methodology proactively promotes double loop learning from previous system failures. Copyright © 2008 John Wiley & Sons, Ltd.
Blood pressure estimation in the human fetal descending aorta
Authors: Struijk P. C. , Mathews V. J. , Loupas T. , Stewart P. A. , Clark E. B. , Steegers E. A. P. , Wladimiroff J. W.
Published: September 2008

Objectives

The objectives of this study were to estimate fetal blood pressure non‐invasively from two‐dimensional color Doppler‐derived aortic blood flow and diameter waveforms, and to compare the results with invasively derived human fetal blood pressures available from the literature.

Methods

Aortic pressures were calculated from digitally recorded color Doppler cineloops of the fetal descending aorta by applying the Womersley model in combination with the two‐element Windkessel model, assuming constant pulse wave velocity during the second half of pregnancy. The results were compared with invasively derived human fetal blood pressures obtained from the literature.

Results

In 21 normal pregnancies the estimated mean aortic pressure regression line increased linearly from 28 mmHg at 20 weeks of gestation to 45 mmHg at 40 weeks of gestation. The pulse pressure based on the regression line increased linearly from 21 mmHg at 20 weeks of gestation to 29 mmHg at 40 weeks of gestation. The aortic compliance exhibited a log linear relationship with the gestational age and a statistically significant eightfold increase was observed between 20 and 40 weeks. The aortic downstream peripheral resistance exhibited an exponentially decaying relationship across the same gestational age range. Non‐invasively derived aortic systolic and diastolic aortic pressures were comparable with previously reported invasively derived systolic and diastolic umbilical arterial pressures; however, the mean pressures differed significantly from those reported in the umbilical artery in a separate study. The aortic systolic pressures calculated in this study were significantly higher than invasively derived left ventricular systolic pressures that have been previously reported in the literature.

Conclusions

This study demonstrates the feasibility of estimating arterial blood pressure in the human fetus. The method described is of potential use in assessing fetal blood pressure non‐invasively, particularly for studying relative changes with time. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.