bluuebunny/crossref_metadata_2025_split huggingface dataset:
An optimal spectrum‐balancing algorithm for digital subscriber lines based on particle swarm optimization
Authors: Tang Meiqin , Long Chengnian , Guan Xinping 
Published: April 2008

AbstractThis paper presents a new algorithm for optimal spectrum balancing in modern digital subscriber line (DSL) systems using particle swarm optimization (PSO). In DSL, crosstalk is one of the major performance bottlenecks, therefore various dynamic spectrum management algorithms have been proposed to reduce excess crosstalks among users by dynamically optimizing transmission power spectra. In fact, the objective function in the spectrum optimization problem is always nonconcave. PSO is a new evolution algorithm based on the movement and intelligence of swarms looking for the most fertile feeding location, which can solve discontinuous, nonconvex and nonlinear problems efficiently. The proposed algorithm optimizes the weighted rate sum. These weights allow the system operator to place differing qualities of service or importance levels on each user, which makes it possible for the system to avoid the selfish‐optimum. We can show that the proposed algorithm converges to the global optimal solutions. Simulation results demonstrate that our algorithm can guarantee fast convergence within a few iterations and solve the nonconvex optimization problems efficiently. Copyright © 2008 John Wiley & Sons, Ltd.
Scaffold Preparation and Parallel Synthesis of Arrays of 5,6,7,8‐Tetrahydropyrrolo‐azepinones in the Solution Phase
Authors: Piras Leonarda , Genesio Eva , Ghiron Chiara , Taddei Maurizio 
Published: April 2008

AbstractAn efficient synthesis of a pyrrolo‐azepine scaffold for the parallel preparation of an array of (oxo‐pyrrolo‐azepinyl)acetamides is described. The Stetter cyclisation of 1,3‐cyclohexanedione with ethyl bromopyruvate was the key reaction in the assembly of a tetrahydrobenzofuran substrate which was submitted to a rapid transformation into a tetrahydroindole by microwave‐assisted cyclocondensation in the presence of glycine. The carbonyl group was then stereoselectively transformed into the corresponding (Z)‐oxime which gave the pyrrolo‐azepinone by Beckmann rearrangement in the presence of polyphosphoric acid. Trimethylaluminium‐mediated amidation gave the corresponding amides which were finally N‐alkylated at the 5‐position to give 52 diverse (pyrrolo‐azepinyl)acetamides, showing an appreciable exploration of the chemical space around the central heterocyclic core. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Particle swarm optimization of TMD by non‐stationary base excitation during earthquake
Authors: Leung A. Y. T. , Zhang Haijun , Cheng C. C. , Lee Y. Y. 
Published: April 2008

AbstractThere are many traditional methods to find the optimum parameters of a tuned mass damper (TMD) subject to stationary base excitations. It is very difficult to obtain the optimum parameters of a TMD subject to non‐stationary base excitations using these traditional optimization techniques. In this paper, by applying particle swarm optimization (PSO) algorithm as a novel evolutionary algorithm, the optimum parameters including the optimum mass ratio, damper damping and tuning frequency of the TMD system attached to a viscously damped single‐degree‐of‐freedom main system subject to non‐stationary excitation can be obtained when taking either the displacement or the acceleration mean square response, as well as their combination, as the cost function. For simplicity of presentation, the non‐stationary excitation is modeled by an evolutionary stationary process in the paper. By means of three numerical examples for different types of non‐stationary ground acceleration models, the results indicate that PSO can be used to find the optimum mass ratio, damper damping and tuning frequency of the non‐stationary TMD system, and it is quite easy to be programmed for practical engineering applications. Copyright © 2008 John Wiley & Sons, Ltd.
Signal Processing. An iterative space subchannel allocation algorithm for multiuser MIMO/OFDM systems
Authors: Xiaofeng Lu , Zan Li , Jueping Cai 
Published: April 2008

AbstractIn multiuser multiple‐input multiple‐output/orthogonal frequency‐division multiplexing (MIMO/OFDM) systems, the EigenValue Decomposition (EVD) method was proposed to construct a number of parallel spatial channels. The beamforming technique which only exploits the spatial subchannel related to the largest eigenvalue is usually adopted in many papers to deal with adaptive resource allocation. Although these previous studies could maximise the received signal‐to‐noise ratio (SNR), they could not get the maximum system throughput. In this paper, all the spatial subchannel are investigated. With the goal of maximising the overall system throughput, we derive a simple effective criterion of subcarrier allocation and introduce an adaptive resource allocation algorithm. The proposed algorithm could get higher system throughput especially at high SNR, that is the spectral efficiency is improved about 3 bit/s/Hz at 14 dB. At the same time, in order to decrease the computational complexity, a time‐frequency blockwise loading design is suggested. In practical channel with partial channel state information (CSI), a modified algorithm based on mean feedback model is proposed. The simulation results show that under imperfect CSI, the modified algorithm could achieve optimum system throughput while guaranteeing prescribed error performance. On the other hand, in comparison to perfect CSI, the system throughput decreases. Copyright © 2008 John Wiley & Sons, Ltd.
Enantiomerically Pure Poly(oxymethylene) Helices: Correlating Helicity with Centrochirality
Authors: Eppacher Simon , Giester Gerald , Bats Jan W. , Noe Christian R. 
Published: April 2008

AbstractA first series of enantiomerically pure helical oligo(formaldehyde)s (=oligo(oxymethylen)s)16–20was synthesized. To induce the chiral uniformity of the helices, we used (1S)‐2,2‐dimethyl‐1‐phenylpropan‐1‐ol (14) to generate the end groups at theαandωterminus (Scheme 6). Propanol14was accessible from its racemate by acetal formation with lactol12and separation of the diastereoisomers (Scheme 5). The helicity of the oligomers was investigated by temperature‐dependent CD, NMR, and optical‐rotation studies. In addition to qualitative considerations concerning the helicity of oligo(formaldehyde)s, we performed calculations of the dimer17and the pentamer20as well as X‐ray structure analyses of the dimer17and the tetramer19to establish the handedness of the helices and to correlate their sense with the absolute configuration of the inducing stereogenic center. The results may be of relevance with respect to induction and propagation of chirality in prebiotic chemistry.
Nanocrystalline ZnO for Knoevenagel Condensation and Reduction of the Carbon,Carbon Double Bond in Conjugated Alkenes
Authors: Hosseini‐Sarvari Mona , Sharghi Hashem , Etemad Samane 
Published: April 2008

AbstractA novel efficient and eco‐friendly nanocrystalline ZnO catalyst was used for the Knoevenagel condensation and for the reduction of CC double bonds at room temperature in the absence of solvents.
Novel Polyketides Isolated from Streptomyces sp.
Authors: Li Jian , Lu Chun‐Hua , Shen Yue‐Mao 
Published: April 2008

AbstractFrom the endophytic strain Streptomyces sp. CS of Maytenus hookeri, five novel type III polyketides, compounds 1–5, were isolated. Their structures were elucidated by spectroscopic analyses including 1D‐ and 2D‐NMR experiments, and by HR‐ESI‐MS.
Optimisation of reactive textile dyes degradation by laccase–mediator system
Authors: Tavares Ana PM , Cristóvão Raquel O , Loureiro José M , Boaventura Rui AR , Macedo Eugénia A 
Published: April 2008

AbstractBACKGROUND: In the textile industry, large quantities of intensely coloured and toxic effluents are released, causing serious environmental pollution. Several biotechnological approaches have been suggested to eliminate this pollution source in an eco‐efficient manner. Laccase can be used to decolourise dyes and its substrate range can be extended by inclusion of a mediator.RESULTS: A screening using several laccase mediators (2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS), 1‐hydroxybenzotriazole (HBT), N‐hydroxyacetanilide (NHA), polioxometalates, violuric acid (VA) and (2,2,6,6‐tetramethylpiperidin‐1‐yloxy) (TEMPO)) was performed on the degradation of six reactive textile dyes. ABTS was the most effective mediator leading to higher decolourisation. The efficiency of ABTS depends on the type of dye, pH, temperature and dye concentration. The optimum temperature and pH values were 35 °C and 5.0, respectively, for maximum decolourisation (above 70%) of reactive black 5, reactive blue 114 and reactive yellow 15. For reactive red 239 the optimum conditions were found to be a temperature of 40 °C and pH of 4.5 (above 56% decolourisation). ABTS has no effect at low concentrations, except for reactive blue 114, where it resulted in the best decolourisation (93%). A comparison of decolourisation based on the percentage absorbance reduction at the maximum absorbance wavelength of each dye and throughout the visible spectrum was made.CONCLUSIONS: These results suggest that the laccase mediator system could be used to treat textile dying wastewaters. Copyright © 2008 Society of Chemical Industry
The mass spectral analysis of isolated hops A‐type proanthocyanidins by electrospray ionization tandem mass spectrometry
Authors: Li Hui‐Jing , Deinzer Max L. 
Published: April 2008

AbstractComprehensive mass spectral fragmentation patterns have been established for sequencing chromatographically isolated A‐type proanthocyanidins (PAs) using electrospray ionization tandem mass spectrometry (ESI‐MSn) in the positive ion mode similar to those used for sequencing previously reported B‐type PAs. Sequence‐identifying fragmentations for A‐type PAs include heterocyclic ring fission (HRF), retro‐Diels–Alder (RDA) fission, benzofuran‐forming (BFF) fission, and quinone methide (QM) fission. There is commonality in fragmentation patterns between A‐type and B‐type PAs, but distinguishing features in the mass spectral patterns between the two classes include 2‐Da mass differences in the pseudo molecular ions, the propensity for the A‐type PAs to undergo QM fissions and yield bis‐quinoid ions as opposed to mono‐quinoid ions in the upper unit of the sequence, and the reluctance of A‐type linkages to undergo RDA, BFF, and BFF/H2O fissions from the upper unit. The positions of one or more A‐type (C2 → O → C7′) ether linkages have been located in sequences of PAs ranging in chain lengths of two to five monomer units using ESI‐MSn data. Using the fragmentation information from ESI‐MSn experiments, a total of 17 PAs were structurally sequenced by systematic real time ESI‐MSn. Among them ten A‐type and six B‐type hop PAs are reported here for the first time. Copyright © 2008 John Wiley & Sons, Ltd.
Integrated beach resorts, informal tourism commerce and the 2004 tsunami: Laguna Phuket in Thailand
Authors: Smith Russell A. , Henderson Joan C. 
Published: April 2008

AbstractIssues of importance related to informal tourism commerce are explored in this paper with particular reference to the case of Laguna Phuket, an integrated beach resort in Thailand. The extent and nature of informal trade at the destination is analysed before and after the Indian Ocean tsunami of 2004, based upon data collected during fieldwork. The sector is shown to display distinctive qualities, including resilience in the face of a natural disaster, and to have a role in purpose‐built as well as conventional resorts. Its relationship with the formal tourism industry is also discussed and this emerges as close, yet with potential for both conflict and cooperation. Copyright © 2008 John Wiley & Sons, Ltd.
Electrogeneration of Polypyrrole/Alginate Films for Immobilization of Glucose Oxidase
Authors: Chen Shuangjun , Chen Wei , Xue Gi 
Published: April 2008

AbstractElectrogenerated PPy doped with pSA was used as a substrate for immobilization of GOD. This was achieved via covalent bonding of carboxyl groups of the main chain of alginate with amino groups of the enzyme. The pH‐induced aggregation behavior of SA in aqueous solution was employed to provide optimum conditions for electrochemical preparation of PPy by galvanostatic methods. GOD was attached to the electrode surface by reaction between the carboxyl groups in the main chain of pSA with amino groups of GOD after treatment with EDC and NHS. The linkage of GOD enzyme to the conductive surface was characterized by ATR spectroscopy and SEM CV was used to demonstrate the bioactivity of the enzyme electrode toward glucose.magnified image
Computational view of surface based organic mass spectrometry
Authors: Garrison Barbara J. , Postawa Zbigniew 
Published: April 2008

AbstractSurface based mass spectrometric approaches fill an important niche in the mass analysis portfolio of tools. The particular niche depends on both the underlying physics and chemistry of molecule ejection as well as experimental characteristics. In this article, we use molecular dynamics computer simulations to elucidate the fundamental processes giving rise to ejection of organic molecules in atomic and cluster secondary ion mass spectrometry (SIMS), massive cluster impact (MCI) mass spectrometry, and matrix‐assisted laser desorption ionization (MALDI) mass spectrometry. This review is aimed at graduate students and experimental researchers. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 289–315, 2008
A statistical study of the weather impact on punctuality at Frankfurt Airport
Authors: Markovic D. , Hauf T. , Röhner P. , Spehr U. 
Published: April 2008

AbstractA hybrid regression/time series modelling was used to relate the total daily punctuality (TOTP) at Frankfurt Airport, Germany, to weather, the traffic flow and the airport system state. The selected modelling approach is applied to the annual, the multi‐annual and seasonal data of the years 2001–2006. Reduction of the initial variables system dimension is achieved through the application of the principal component analysis (PCA) method. The portion of the variability that can be explained by the model after correction of autocorrelations in the residuals using autoregressive (AR) models, is between 60 and 69%. A slight year‐to‐year variability in the number of statistically significant model parameters is detected. Upon identification of the terminal‐specific delay impact factors, the possibility of the 24 h punctuality forecast for the interval of 1 year was discussed. Copyright © 2008 Royal Meteorological Society
Three‐dimensional spatial interpolation of surface meteorological observations from high‐resolution local networks
Authors: Uboldi Francesco , Lussana Cristian , Salvati Marta 
Published: April 2008

AbstractAn objective analysis technique is applied to a local, high‐resolution meteorological observation network in the presence of complex topography. The choice of optimal interpolation (OI) makes it possible to implement a standard spatial interpolation algorithm efficiently. At the same time OI constitutes a basis to develop, in perspective, a full multivariate data assimilation scheme. In the absence of a background model field, a simple and effective de‐trending procedure is implemented. Three‐dimensional correlation functions are used to account for the orographic distribution of observing stations. Minimum‐scale correlation parameters are estimated by means of the integral data influence (IDI) field. Hourly analysis fields of temperature and relative humidity are routinely produced at the Regional Weather Service of Lombardia. The analysis maps show significant informational content even in the presence of strong gradients and infrequent meteorological situations. Quantitative evaluation of the analysis fields is performed by systematically computing their cross validation (CV) scores and by estimating the analysis bias. Further developments concern the implementation of an automatic quality control procedure and the improvement of error covariance estimation. Copyright © 2008 Royal Meteorological Society
Manganese‐enhanced MRI detection of neurodegeneration in neonatal hypoxic‐ischemic cerebral injury
Authors: Yang Jian , Khong Pek‐Lan , Wang Yanxin , Chu Andrew Chi‐Yuen , Ho Shu‐Leong , Cheung Pik‐To , Wu Ed X. 
Published: April 2008

AbstractIn this study, we investigated the Mn‐enhanced MRI (MEMRI) for detecting neurodegenerative processes in neonatal hypoxic‐ischemic (H‐I) cerebral injury. Seven‐day‐old rats were induced with H‐I injury, and scanned for T1‐weighted image (T1WI) and T2‐weighted image (T2WI) with and without systemic MnCl2 administration. Serial histological analysis was performed for Mn‐superoxide dismutase (Mn‐SOD) and glutamine synthetase (GS), which are Mn‐binding enzymes against the oxidative stress and glutamate excitotoxicity in neurodegeneration. In the acute phase (first 2 days), the ipsilateral lesion exhibited no Mn enhancement in T1WIs, with histology showing no Mn‐SOD and GS production. In the mid‐phase (from day 3), Mn enhancement was found in the cortex, basal ganglia, and hippocampus, correlating with local Mn‐SOD and GS increase. In the late phase, the enhancement became more localized to the pericyst basal ganglia and cortex, and then gradually diminished. In T2WIs, a signal decrease was observed from day 3 in the corresponding regions. Hypointense voids gradually formed in the late phase, correlating with the local iron accumulation. H‐I rats without Mn2+ administration exhibited similar but weak changes in T1WIs and T2WIs from days 14 and 7, respectively. These results indicate that Mn2+ may be a useful in vivo probe for monitoring Mn‐SOD and GS enzymatic activities. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Oxygen‐enhanced MR imaging of mice lungs
Authors: Watt K.N. , Bishop J. , Nieman B.J. , Henkelman R.M. , Chen X.J. 
Published: April 2008

AbstractInhaled molecular oxygen has been widely used in humans to evaluate pulmonary ventilation using MRI. MR imaging has recently played a greater role in examining the morphologic and physiologic characteristics of mouse models of lung disease where structural changes are highly correlated to abnormalities in respiratory function. The motivation of this work is to develop oxygen‐enhanced MR imaging for mice. Conventional human MR techniques cannot be directly applied to mouse imaging due to smaller dimensions and faster cardiac and respiratory physiology. This study examines the development of oxygen‐enhanced MR as a noninvasive tool to assess regional ventilation in spontaneously breathing mice. An optimized cardiac‐triggered, respiratory‐gated fast spin‐echo imaging sequence was developed to address demands of attaining adequate signal from the parenchyma, maintaining practical acquisition times, and compensating for rapid physiological motion. On average, a 20% T1‐shortening effect was observed in mice breathing 100% oxygen as compared to air. The effect of ventilation was shown as a significant signal intensity increase of 11% to 16% in the mouse parenchyma with 100% oxygen inhalation. This work demonstrates that adequate contrast and resolution can be achieved using oxygen‐enhanced MR to visualize ventilation, providing an effective technique to study ventilation defects in mice. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Mimicking the human expert: Pattern recognition for an automated assessment of data quality in MR spectroscopic images
Authors: Menze Bjoern H. , Kelm B. Michael , Weber Marc‐André , Bachert Peter , Hamprecht Fred A. 
Published: April 2008

AbstractBesides the diagnostic evaluation of a spectrum, the assessment of its quality and a check for plausibility of its information remains a highly interactive and thus time‐consuming process in MR spectroscopic imaging (MRSI) data analysis. In the automation of this quality control, a score is proposed that is obtained by training a machine learning classifier on a representative set of spectra that have previously been classified by experts into evaluable data and nonevaluable data. In the first quantitative evaluation of different quality measures on a test set of 45,312 long echo time spectra in the diagnosis of brain tumor, the proposed pattern recognition (using the random forest classifier) separated high‐ and low‐quality spectra comparable to the human operator (area‐under‐the‐curve of the receiver‐operator‐characteristic, AUC >0.993), and performed better than decision rules based on the signal‐to‐noise‐ratio (AUC <0.934) or the estimated Cramér‐Rao‐bound on the errors of a spectral fitting (AUC <0.952). This probabilistic assessment of the data quality provides comprehensible confidence images and allows filtering the input of any subsequent data processing, i.e., quantitation or pattern recognition, in an automated fashion. It thus can increase robustness and reliability of the final diagnostic evaluation and allows for the automation of a tedious part of MRSI data analysis. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
What do epidemiologists mean by ‘population mixing’?
Authors: Law Graham R. , Feltbower Richard G. , Taylor John C. , Parslow Roger C. , Gilthorpe Mark S. , Boyle Paul , McKinney Patricia A. 
Published: April 2008

AbstractThere is growing evidence that some chronic diseases are caused, or promoted, by infectious disease. ‘Population mixing’ has been used as a proxy for the range and dose of infectious agents circulating in a community. Given the speculation over the role of population mixing in many chronic diseases, we review the various methods used for measuring population mixing, and provide a classification of these. We recommend that authors fulfill two criteria in publications: measures are demonstrably associated with the putative risk factors for which population‐mixing is acting as a proxy and fundamental characteristics of the chosen measures are clearly defined. Pediatr Blood Cancer 2008;51:155–160. © 2008 Wiley‐Liss, Inc.
C‐erbB‐2 expression and prognostic significance in osteosarcoma
Authors: Yalçın Bilgehan , Gedikoğlu Gökhan , Kutluk Tezer , Varan Ali , Akyüz Canan , Büyükpamukçu Münevver 
Published: April 2008

AbstractBackgroundC‐erbB‐2 is postulated as a prognostic biological marker for osteosarcoma (OST). We investigated c‐erbB‐2 expression status in osteosarcomas and its prognostic significance.ProcedureArchival pre‐treatment tumor biopsies of 79 cases were stained by immunohistochemical (IHC) methods with CB11 antibody for cell‐membrane specific c‐erbB‐2 expression. Relation with different variables was examined and survival rates were calculated.ResultsMedian age was 13 years (7–17). Distant metastases were detected in 8 (10.1%) cases at initial diagnosis. 36/79 (45.6%) patients had positive c‐erbB‐2 staining by IHC. There was no significant difference between c‐erbB‐2 expression and presence of distant metastases at initial diagnosis or during follow‐up, gender, age groups, tumor size, tumor sites, serum alkaline phosphatase, and lactate dehydrogenase levels. At a median follow‐up of 67.4 months (9.2–246.1), 36 cases died, 20 were alive, and 23 abandoned treatment. For 58 cases without initial metastases who underwent definitive surgery, 5‐year event‐free (EFS) and overall survival (OS) rates were 50% and 62.1% in cases negative for c‐erbB‐2 expression, and 22.4% and 32.3% in cases positive for c‐erbB‐2 expression, respectively (EFS,P = 0.044; OS,P = 0.029). Five‐year EFS and OS rates were significantly higher in cases with a tumor size <10 cm. Cox regression analyses revealed that only size persisted as a prognostic factor for EFS. C‐erbB‐2 expression status didn't appear as an independent prognostic factor.ConclusionsOverexpression of c‐erbB‐2 in OST was not correlated with metastatic potential. No independent prognostic significance was detected. The results do not support directed therapies for c‐erbB‐2 in OST. Pediatr Blood Cancer 2008;51:222–227. © 2008 Wiley‐Liss, Inc.