bluuebunny/crossref_metadata_2025 huggingface dataset:
An Alternative Mechanism for Diels–Alder Reactions of Evans Auxiliary Derivatives
Authors: Bakalova Snezhana M. , Duarte Filipe J. S. , Georgieva Miglena K. , Cabrita Eurico J. , Santos A. Gil
Published: July 2009

The mechanism proposed by Evans for the dialkylaluminum chloride promoted Diels–Alder reaction of cyclopentadiene with α,β‐unsaturated N‐acyloxazolidinones has been widely used as a basis for the rationalization of the experimental selectivities observed in many different types of reactions in which oxazolidinones or imidazolidinones are used as chiral auxiliaries. In this manuscript we introduce a new and more general model based on molecular modeling and NMR spectroscopy data that avoids several ambiguous concepts raised by the Evans model and fully explains all available experimental data. While the Evans proposal relies on the formation of high‐energetic ionic chelates that promote the rotation of the amide bond in the N‐acyloxazolidinone molecule, our model is based on the catalysis by means of low‐energetic mono‐ or bicomplexes at the chain and the ring carbonyl groups that are easily observed by NMR spectroscopy measurements. The observed selectivities are explained by a chirality‐transfer concept, in which an achiral Lewis acid works as a bridge for the transfer of chirality between a chiral auxiliary and a prochiral reactive center. Different to the Evans proposal, this mechanism fully explains the experimental selectivities for low Lewis acid concentrations, based on the catalysis by means of concurrent monocomplexes at the chain or the ring carbonyl groups, as well as the increased reaction rates and selectivities experimentally observed for high Lewis acid concentrations. The model can be extrapolated to nonchelating and other chelating Lewis acids, thereby allowing for the rationalization of much experimental data that were never explained by the Evans proposal.
Computational model of whole blood exhibiting lateral platelet motion induced by red blood cells
Authors: Crowl Lindsay M. , Fogelson Aaron L.
Published: July 2009

An Immersed Boundary method is developed in which the fluid's motion is calculated using the lattice Boltzmann method. The method is applied to explore the experimentally observed lateral redistribution of platelets and platelet‐sized particles in concentrated suspensions of red blood cells undergoing channel flow. Simulations capture red‐blood‐cell‐induced lateral platelet motion and the consequent development of a platelet concentration profile that includes an enhanced concentration within a few microns of the channel walls. In the simulations, the near‐wall‐enhanced concentration develops within approximately 400 ms starting from a random distribution of red blood cells and a uniform distribution of platelet‐sized particles. Copyright © 2009 John Wiley & Sons, Ltd.
Elastodynamic analysis of multiple crack problem in 3‐D bi‐materials by a BEM
Authors: Mykhas'kiv V. , Zhbadynskyi I. , Zhang Ch.
Published: July 2009

The three‐dimensional (3‐D) problem of bi‐materials or two ideally bonded elastic half‐spaces with interacting sub‐interface cracks subjected to time‐harmonic loading is analyzed. The boundary value problem is reduced to a system of boundary integral equations (BIEs) in the frequency domain for the crack‐opening‐displacements (CODs) only. Boundary integrals over the finite crack‐surfaces are obtained by introducing modified elastodynamic Green's functions, which identically satisfy the contact conditions on the infinite interface. The singularity subtraction technique under consideration of the ‘square‐root’ behavior of the CODs at the crack‐front is applied for the regularization of the BIEs. By using a collocation scheme, the BIEs are converted into a system of linear algebraic equations. Numerical calculations are performed for a bi‐material with two penny‐shaped cracks located on both sides of the interface subjected to time‐harmonic tensile loading of constant amplitude on the crack‐surfaces. Numerical results for the mode‐I dynamic stress intensity factor as a function of the wave number are presented and discussed for various material combinations and distances between the interface and the cracks. Copyright © 2009 John Wiley & Sons, Ltd.
Reduced‐order modelling for solving linear and non‐linear equations
Authors: Verdon N. , Allery C. , Béghein C. , Hamdouni A. , Ryckelynck D.
Published: July 2009

In this article, we present some investigations about the solving of transfer equations by reduced‐order models (ROM). We introduce a ROM, the
a priori reduction (APR), and we present the results obtained for the 2D unsteady convection–diffusion equation and the 1D Burgers equation. The APR approach is then compared with the Karhunen–Loève decomposition and some properties of this method are emphasized. We show that the computation time necessary for solving these transfer equations is reduced, whereas the accuracy is of the same order of magnitude, in comparison with the solution obtained for the full model with classical methods. At last it is noticed that the APR method is an efficient way to correct the long term behavior of low order dynamical systems. Copyright © 2009 John Wiley & Sons, Ltd.
Robustness in complex information systems: The role of information “barriers” in Boolean networks
Authors: Richardson Kurt A.
Published: July 2009

In this supposed “information age,” a high premium is put on the widespread availability of information. Access to as much information as possible is often cited as key to the making of effective decisions. While it would be foolish to deny the central role that information and its flow has in effective decision‐making processes, this chapter explores the equally important role of “barriers” to information flows in the robustness of complex systems. The analysis demonstrates that (for simple Boolean networks at least) a complex system's ability to filter out, i.e., block, certain information flows is essential if it is not to be beholden to every external signal. The reduction of information is as important as the availability of information. © 2009 Wiley Periodicals, Inc. Complexity, 2010
Digital architectures realizing piecewise‐linear multivariate functions: Two FPGA implementations
Authors: Storace Marco , Poggi Tomaso
Published: July 2009

Digital architectures for the circuit realization of multivariate piecewise‐linear (PWL) functions are reviewed and compared. The output of the circuits is a digital word representing the value of the PWL function at then‐dimensional input. In particular, we propose two architectures with different levels of parallelism/complexity. PWL functions withn= 3 inputs are implemented on an FPGA and experimental results are shown. The accuracy in the representation of PWL functions is tested through three benchmark examples, two concerning three‐variate static functions and one concerning a dynamical control system defined by a bi‐variate PWL function. Copyright © 2009 John Wiley & Sons, Ltd.
NHAR: A non‐homogeneous Arnoldi method for fast simulation of RCL circuits with a large number of ports
Authors: Zeng Xuan , Yang Fan , Su Yangfeng , Cai Wei
Published: July 2009

Large‐scale RCL circuits with a large number of ports have been widely employed to model interconnect circuits, such as the power/ground networks, clock distribution networks and large data buses in VLSI. The input‐dependent moment‐matching technique, which takes the input excitations into account when constructing the projection matrices for the reduced‐order systems, has been proposed to simulate this type of circuits. The existing input‐dependent moment‐matching methods suffer from either numerical instability in the case of extended Krylov subspace (EKS) and improved extended Krylov subspace (IEKS) methods, or unbearable memory consumption and CPU cost for the EXPanded LINearization (EXPLIN) method. In this paper, a Non‐Homogeneous ARnoldi (NHAR) process, which consists of a memory‐saving and computation‐efficient linearization scheme and a numerical stable partial orthogonalization Arnoldi method, is proposed for the generation of the orthonormal projection matrix. By applying the obtained projection matrix to generate the reduced‐order model, we derive the NHAR method for the model‐order reduction of large‐scale RCL circuits with a large number of ports. The proposed NHAR method can guarantee moment matching, numerical stability and passivity preserving. Compared with the EXPLIN method, NHAR can remarkably reduce the size of the linearized system and therefore can greatly save the memory consumption and computational cost with almost the same accuracy. Moreover, NHAR is numerically stable and can achieve higher accuracy with approximately the same computational cost compared with the EKS and IEKS methods. Copyright © 2009 John Wiley & Sons, Ltd.
Quadrature VCOs based on direct second harmonic locking: Theoretical analysis and experimental validation
Authors: Tortori Paola , Guermandi Davide , Guermandi Marco , Franchi Eleonora , Gnudi Antonio
Published: July 2009

We propose a theoretical analysis of the class of quadrature VCOs (QVCOs) based on two LC‐oscillators directly coupled by means of the second harmonic. The analysis provides the conditions for the existence and stability of steady‐state quadrature oscillations and a simplified model for the phase noise (PN) transfer function with respect to a noise source in parallel to the tank. We show that the figure of merit defined as the product between PN and current equals that of the single VCO, confirming that quadrature generation is achieved by this class of QVCO without degrading that figure of merit. An analytical model for the phase quadrature error due to tank mismatches is also proposed. The validity of all analytical models is discussed against numerical simulations. A practical implementation at 3.26 GHz with ±20% tuning range in a 0.13µm CMOS technology is also presented, confirming the main theoretical findings. Copyright © 2009 John Wiley & Sons, Ltd.
Asynchronous demodulation technique for use in vision sensor image classification and segmentation
Authors: Habibi M. , Sayedi S. M.
Published: July 2009

This paper presents a novel technique for classification and segmentation of a multiple‐object image scene. Each object in the scene is tagged by a flashing LED operating at a specific frequency. The vision sensor, based on this technique, demodulates the captured light signal, omits the background illumination, and performs classification by assigning a unique ID‐tag to each region based on its flashing light frequency. The process is performed in‐pixel by an asynchronous demodulation and frequency identification circuit, which is designed in a standard 0.6µm CMOS technology. Simulation results confirm the validity of the proposed structure. At a frame rate of 250 fps the power consumption is 2.6µW/pixel, which is relatively low compared with those of sensors with similar functionality. The structure is intended for use as a low power, inexpensive solution in robot visual position feedback and localization. Copyright © 2009 John Wiley & Sons, Ltd.
Pro‐Hepcidin Levels in Peritoneal Dialysis and Hemodialysis Patients
Authors: Turgut Faruk , Kanbay Mehmet , Altay Mustafa , Uz Ebru , Bavbek Nuket , Koca Cemile , Secilmis Sema , Duranay Murat , Akcay Ali , Covic Adrian
Published: July 2009

OBJECTIVE

Anemia is a major clinical problem in patients receiving dialysis therapy and has a substantial impact on morbidity and mortality. Iron metabolism is impaired in chronic kidney disease. Hepcidin functions as a key regulator of iron metabolism. The aims of this study were to compare the serum pro‐hepcidin levels in patients with either peritoneal dialysis (PD) or hemodialysis (HD) and control subjects and to evaluate pro‐hepcidin and C‐reactive protein (CRP), iron parameters, and hemoglobin levels in PD and HD patients with normal serum CRP levels.

METHODS

We studied 85 PD patients, 43 HD patients on regular follow‐up, and a control group that was comprised of 41 volunteers in this cross‐sectional study. Pro‐hepcidin and CRP were studied using commercially available kits. Iron status was assessed by measuring serum iron, transferrin saturation, and ferritin.

RESULTS

Pro‐hepcidin levels were significantly higher in dialysis patients than the control subjects (p < .001). Hemodialysis patients had higher pro‐hepcidin levels than PD patients; but, this difference was not statistically significant (393.4 ± 157.3 versus 361.3 ± 40.1, p = .19). There were no correlations between pro‐hepcidin levels and CRP, and hemoglobin level and iron parameters in PD and HD patients.

CONCLUSION

The present results suggest that dialysis therapy is associated with elevated pro‐hepcidin levels and not directly related to CRP, indices of iron metabolism, or hemoglobin levels. Peritoneal dialysis patients have relatively lower pro‐hepcidin levels than HD patients, but larger‐scale studies are needed to confirm the possibility of impact on various dialytic modalities.
Renal Allograft Outcomes From Spousal and Other Living‐Unrelated Donors
Authors: Lee Yu‐Ji , Lee Jung Eun , Kim Sung‐Joo , Kim Yoon‐Goo , Kim Dae Joong , Oh Ha‐Young , Huh Wooseong
Published: July 2009

OBJECTIVE

The objective of this study was to compare renal allograft outcomes from spousal donors with those from other living‐unrelated donors (LUD), and to make the best use of spousal donors.

METHODS

From February 1995 to February 2006, 812 renal transplantations were performed at our center, of which 185 were from LUDs. A retrospective analysis was made of all recipients who successfully underwent living‐unrelated renal transplantation.

RESULTS

A total of 55 out of the 185 recipients received a kidney from their spouses. Compared with other LUDs, spousal donors were older and had poorer human leukocyte antigen (HLA) mismatching. The time from initiation of dialysis to transplantation was shorter in transplantation from spousal donors. The incidence of acute rejection within the first year after transplantation was more frequent in spousal grafts. However 1‐year and 5‐year survival rates for spousal and other living‐unrelated grafts were not significantly different (96.3% and 93.7% for spousal grafts versus 97.7% and 89.3% for other living‐unrelated grafts, p = .925). The survival rate for 5‐year patients was 96.4% and 97.5%, respectively.

DISCUSSION

Transplantation from spousal donors has comparable outcomes to those of other LUDs, and shortens time spent on the waiting list. Therefore, spousal donation should be considered as a useful source to overcome an organ shortage.
Fatigue in People Undergoing Hemodialysis
Authors: Mollaoglu Mukadder
Published: July 2009

BACKGROUND

Fatigue, a common symptom reported by people with end‐stage renal disease (ESRD), is a nonspecific and invisible symptom and is a phenomenon that is poorly understood by healthcare professionals. There is limited understanding of the level of fatigue experienced by people with ESRD, with research currently limited to people treated with hemodialysis.

AIM

Levels of fatigue as experienced by people undergoing hemodialysis (HD) were assessed using the Visual Analog Scale for Fatigue (VAS‐F).

METHOD

The VAS‐F was completed by 138 people with ESRD who were patients of HD units in Sivas, Turkey. Demographic and renal health history data were also collected with a structured questionnaire. The statistical analyses used in order to evaluate the data include: student's t‐test, Kruskal‐Wallis test, Pearson correlation test, and logistic regression analysis.

RESULTS

The level of fatigue experienced by people with HD in our study was high, and their energy level was low. Univariate analysis showed that levels of fatigue differed by gender, age, education, employment, and presence of anemia. However, logistic regression analysis, age, and duration of dialysis were found to be the independent predictors of fatigue.

CONCLUSIONS

The results of the study indicated that high levels of fatigue are experienced. In order to improve patient care and promote patient's quality of life, nephrology professionals should understand the comprehensive assessment of fatigue and work with patients to initiate a range of strategies and interventions to address it.
Scopoletin induces apoptosis of fibroblast‐like synoviocytes from adjuvant arthritis rats by a mitochondrial‐dependent pathway
Authors: Li Ying , Dai Yue , Liu Mei , Pan Rong , Luo Yubin , Xia Yufeng , Xia Xiaofeng
Published: July 2009

Scopoletin is a naturally occurring coumarin compound found in many medicinal plants, such as Erycibe obtusifolia Benth and Aster tataricus. Our previous studies have demonstrated that this compound could ameliorate adjuvant‐induced arthritis in a rat model of human rheumatoid arthritis (RA). Since the proliferation of fibroblast‐like synoviocytes (FLS) plays a pivotal role in the formation and growth of pannus, which leads to subsequent joint destruction in RA, we examined the effects of scopoletin on FLS apoptosis. Primary FLS from adjuvant arthritis rats were purified and cultured, and then treated with increasing concentrations of scopoletin (250, 500, 1,000 µM) for 24 h. Scopoletin decreased the viability of FLS in a dose‐dependent manner and remarkably induced their apoptosis, as revealed by Hochest 33258 staining and flow cytometry analysis. Further experiments showed that scopoletin activated caspase‐3, depolarized mitochondrial membrane potential, regulated expression of bcl‐2 family members, and reduced the activation of NF‐κB proteins. These results indicated that scopoletin induced apoptosis of FLS through a mitochondrial‐dependent pathway, which may be mediated by inhibition of NF‐κB activation and promotion of caspase‐3 activation. Drug Dev Res, 2009. © 2009 Wiley‐Liss, Inc.
Cognitive profiles of chinese adolescents with dyslexia
Authors: Chung Kevin K. H. , Ho Connie Suk‐Han , Chan David W. , Tsang Suk‐Man , Lee Suk‐Han
Published: July 2009

The present study sought to identify cognitive abilities that might distinguish Hong Kong Chinese adolescents with and without dyslexia and examined the cognitive profile of dyslexic adolescents in order to better understand this important problem. The performance of 27 Chinese adolescents with childhood diagnoses of dyslexia was compared with 27 adolescents of the same chronological age (CA) and 27 of matched reading level (RL) on measures of literacy and cognitive abilities: Chinese word reading, one‐minute reading, reading comprehension, dictation, verbal short‐term memory, rapid naming, visual‐orthographic knowledge, morphological and phonological awareness. The results indicated that the dyslexic group scored lower than the CA group, but similar to the RL group, especially in the areas of rapid naming, visual‐orthographic knowledge and morphological awareness, with over half having multiple deficits exhibited 2 or more cognitive areas. Furthermore, the number of cognitive deficits was associated with the degree of reading and spelling impairment. These findings suggest that adolescents with childhood diagnoses of dyslexia have persistent literacy difficulties and seem to have multiple causes for reading difficulties in Chinese. Copyright © 2009 John Wiley & Sons, Ltd.
Moisture controls on CO2 exchange in a Sphagnum‐dominated peatland: results from an extreme drought field experiment
Authors: Strack M. , Waddington J. M , Lucchese M. C , Cagampan J. P
Published: July 2009

Peatlands store globally significant quantities of soil carbon, and Sphagnum moss is the main peat forming vegetation type in bogs. Sphagnum moss productivity is driven by the moisture content of its apical cluster of branches, the capitulum. Capitulum moisture content is dependent on the arrangement of leaves, branches and stems for a given species and also on hydrological conditions of the underlying peat. Despite this link, the response of CO2 exchange in Sphagnum‐dominated peatlands to extreme drought is still unclear, particularly under field conditions.

We used drainage to expose Sphagnum rubellum to extreme drought and monitored water table, volumetric water content (VWC), gross ecosystem photosynthesis (GEP), ecosystem respiration (ER) and net ecosystem exchange of CO2 (NEE) at plots in a 25 m transect perpendicular to a deep drainage ditch and compared results to an undrained site. VWC in the upper 10 cm of peat was strongly related to water table at depths shallower than 55 cm. Below this depth, near surface VWC remained relatively constant between 25 and 28% and Sphagnum GEP was effectively shut down. This also resulted in decreased ER at these locations. The combined effect was a linear relationship between VWC and NEE with moist sites acting as net CO2 sinks (up to −5 g CO2 m−2 day−1) whereas sites closest to the ditch were consistently small carbon sources. We suggest that understanding how climate change will alter peatland hydrology relative to the moisture thresholds of Sphagnum mosses is critical to determining the fate of their carbon sink function. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis, Insertion Reactivity, and Transmetalation Reactions of the Lithium Complex [{2‐(6‐R‐Pyr)(Me3Si)}CHLi·OEt2]2 (R = H or Me)
Authors: Chen Xia , Guan Lingling , Eisen Moris S. , Li Haifen , Tong Hongbo , Zhang Liping , Liu Diansheng
Published: July 2009

Treatment of 6‐R‐2‐(Me3SiCH2)C5H3N (R = H or Me) with nBuLi in diethyl ether affords the dimeric lithium complexes [{2‐(6‐R‐Pyr)(Me3Si)}CHLi·OEt2]2 (Pyr = pyridine, C5H3N) in high yields. In these complexes, the two anionic ligands have different bonding modes. These complexes easily undergo insertion reactions with nitriles to form six‐membered cyclic dimeric complexes in good yields. Further transmetalations of the six‐membered cyclic complexes with CuCl, SnCl4, or CoCl2 allow the formation of new metal complexes that maintain the frameworks of the six‐membered metallacycles. All complexes represented above were fully characterized by methods including single‐crystal X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
X‐ray Structures, Spectroscopic and Magnetic Studies of a Coordination Polymer Series Based on a TTF Derivative and Paramagnetic Transition Metals
Authors: Olivier Jean , Golhen Stéphane , Świetlik Roman , Cador Olivier , Pointillart Fabrice , Ouahab Lahcène
Published: July 2009

The oxidation of 2,3,6,7‐tetrakis(2‐cyanoethylthio)tetrathiafulvalene (TCE‐TTF) with hexafluoroacetylacetonate (hfac) salts of paramagnetic (CoII, MnII) and diamagnetic (ZnII, CdII) ions in the presence of tetrahedral anions (BF4– and ClO4–) resulted in the isolation of four isostructural salts. The structure of these salts revealed an infinite two‐dimensional network due to the coordination of the nitrilo arms of TCE‐TTF to the metal. Short interplanar S···S interactions between two planes involving TCE‐TTF give a third dimension to this polymer. TTF ligands are fully oxidized, and hence these materials show semiconducting behaviour. Spectroscopic and magnetic studies of the paramagnetic‐transition‐metal‐containing polymers are also presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis of Chiral Bridled Porphyrins in their Two Enantiomeric Forms
Authors: Fateeva Alexandra , Pécaut Jacques , Bayle Pierre‐Alain , Maldivi Pascale , Dubois Lionel
Published: July 2009

We describe the synthesis of a new family of chiral bridled porphyrins. They were obtained by reaction between pyrrole and a chiral 2‐formylcyclohexanol derivative. Thanks to an enzymatic kinetic resolution method, these compounds were obtained in both enantiomeric forms. This resolution method allows easy synthesis of chiral precursors in high yield and on large scale. These new porphyrins exhibited an (αα)(αα) conformation and the less usual (αα)(ββ) one, depending of the bridle length.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Efficient Synthesis and Cytotoxic Activity of Some Symmetrical Disulfides Derived from the Quinolin‐4(1H)‐one Skeleton
Authors: Soural Miroslav , Hlaváč Jan , Hradil Pavel , Hajdúch Marián
Published: July 2009

The preparation of novel organic disulfides containing the 2‐(substituted phenyl)quinolin‐4(1H)‐one ring is described. The synthesis starts from thioanthranilic acid esterified with various bromoacetophenones. Cyclization of the resulting phenacyl thioanthranilates in trifluoroacetic acid afforded a mixture of 2‐(substituted phenyl)‐3‐sulfanylquinolin‐4(1H)‐ones and 3,3′‐disulfanediylbis[2‐(substituted phenyl)quinolin‐4(1H)‐ones]. Heating of the mixture in o‐xylene gave 3,3′‐disulfanediylbis[2‐(substituted phenyl)quinolin‐4(1H)‐ones]of high purity. The disulfides exhibited a significant in vitro cytotoxicity against various cancer cell lines including polyresistant subclones. The data obtained are reported and discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Mimicking disliked others: Effects of a priori liking on the mimicry‐liking link
Authors: Stel Mariëlle , Blascovich Jim , McCall Cade , Mastop Jessanne , van Baaren Rick B. , Vonk Roos
Published: July 2009

The sharing of bodily states elicits in mimicker and mimickee corresponding conceptualisations, which facilitates liking. There are many studies showing the relatedness of mimicry and liking. However, the mimicry‐liking link has not been investigated under conditions in which the mimickee is liked or disliked a priori. In two studies, we examined moderating effects of a priori liking on the mimicry‐liking link. Liking was measured via self‐report measures (Studies 1 and 2) and behavioural measures using a virtual environment technology (Study 2). Results showed that when participants intentionally mimicked a disliked person, liking for that person was not improved, whereas when participants mimicked a liked person, liking for that person increased. These effects were shown to be mediated by affiliation. These studies not only provided further evidence of a link between mimicry and liking, but also demonstrated that this relationship is moderated by a priori liking. Copyright © 2009 John Wiley & Sons, Ltd.
The benefits of empathy: When empathy may sustain cooperation in social dilemmas
Authors: Rumble Ann C. , Van Lange Paul A. M. , Parks Craig D.
Published: July 2009

Cooperation in social dilemmas is often challenged by negative noise, or unintended errors, such that the actual behavior is less cooperative than intended—for example, arriving later than intended for a meeting due to an unusual traffic jam. The present research was inspired by the notion that doing a little more for one's interaction partner, which may be movitvated by empathetic feelings, can effectively reduce the detrimental effects of “negative noise,” or unintended incidents of noncooperation. Consistent with hypotheses, negative noise exhibited detrimental effects on cooperation, but such effects were absent when empathy‐motivated cooperation was present. We conclude that empathy has broad benefits for social interaction, in that it can be an effective tool for coping with misinterpreted behaviors, thereby maintaining or enhancing cooperation. Copyright © 2009 John Wiley & Sons, Ltd.
CE with a new electrochemiluminescent detection system for separation and detection of proteins labeled with tris(1,10‐phenanthroline) ruthenium(II)
Authors: Guo Longhua , Qiu Bin , Xue Linlin , Chen Guonan
Published: July 2009

In this article, a CE with a new electrochemiluminescent (ECL) detection system was developed. A microfluidic ECL detection cell with less than 0.5 μL dead volumes was developed and used as detector for this system. A hydrofluoric acid‐etched porous joint was made at 8 mm from the outlet of the separation capillary to isolate the CE high voltage from ECL detection. The proposed CE‐ECL system was applied for separation and detection of some proteins labeled with tris(1,10‐phenanthroline) ruthenium(II). High efficiency ECL‐enhanced reagent, tripropylamine, was infused to the detection cell as coreactant by a micro‐infusion system to obtain maximum and stable ECL signal. The performance of this setup was illustrated by the analysis of tris(1,10‐phenanthroline) ruthenium(II)‐labeled proteins. The background electrolyte for protein detection was 20 mM Tris‐CH3COOH with 2.0% m/m PVP at pH 4.0. Under the optimal conditions, the corresponding LOD were 2.2×10−10 M for HSA, 4.4×10−10 M for casein (α‐S1) and 5.1×10−10 M for cytochrome c. The proposed method was also successfully used for the trace analysis of albumin in human urine without any pretreatment.
Separation of peptides by open‐tubular capillary electrochromatography using Fe(III)‐deuteroporphyrin as a covalently attached stationary phase
Authors: Yone Ángel , Carballo Romina R. , Rezzano Irene N. , Vizioli Nora M.
Published: July 2009

The separation of seven biologically active peptides was attempted by open‐tubular capillary electrochromatography in fused‐silica capillaries chemically modified with iron (III)‐deuteroporphyrin using UV‐absorption detection at 214 nm. The effect of BGE pH and content of organic solvent modifier was investigated. The best separations were obtained in 25 mM phosphate (BGE), pH 4.0, containing 5% v/v ACN and 10 mM hydroquinone, which was added to prevent gas bubble formation. Considering the method sensitivity, lower concentration LODs were obtained for all peptides in their open‐tubular capillary electrochromatography separation as compared with their CZE separation in bare fused‐silica capillary. The iron (III)‐deuteroporphyrin column proved to be highly stable over time and showed acceptable precision of migration times and corrected peak areas (RSD in the range 2–4%).
The multi‐clump finite mixture distribution and model selection
Authors: Paul Sudhir R. , Banerjee Tathagata , Balasoorya Uditha
Published: July 2009

In practical data analysis, often an important problem is to determine the number of clumps in discrete data in the form of proportions. This can be done through model selection in a multi‐clump finite mixture model. In this paper, we propose bootstrap likelihood ratio tests to test the fit of a multinomial model against the single clump finite mixture distribution and to determine the number of clumps in the data, that is, to select a model with appropriate number of clumps. Shortcomings of some traditional large sample procedures are also shown. Three datasets are analyzed. Copyright © 2009 John Wiley & Sons, Ltd.
A compound Poisson model for the annual area burned by forest fires in the province of Ontario
Authors: Podur Justin J. , Martell David L. , Stanford David
Published: July 2009

We use the compound Poisson probability distribution to model the annual area burned by forest fires in the Canadian province of Ontario. Models for sums‐of‐random variables, relevant for modeling aggregate insurance claims and assessing insurance risk are also relevant in modeling aggregate area burned based on sums of sizes of individual fires. Researchers have fit the distribution of fire sizes to the truncated power‐law (or Pareto) distribution (Wardet al., 2001) and a four‐parameter Weibull distribution (Reed and McKelvey,2002). Armstrong (1999) fitted a lognormal distribution to annual proportion of area burned by forest fires in a region of Alberta. We derive expressions and moments for aggregate area burned in Ontario using fire data from the Ontario Ministry of Natural Resources (OMNR). We derive expressions for the distribution of area burned for “severe” and “mild” fire weather scenarios and for “intensive suppression” and “no suppression” scenarios (represented by the intensive and extensive fire protection zones of the province). These distributions can be used to perform risk analysis of annual area burned. Copyright © 2009 John Wiley & Sons, Ltd.
Berm formation and dynamics on a gently sloping beach; the effect of water level and swash overtopping
Authors: Jensen Stine G. , Aagaard Troels , Baldock Tom E. , Kroon Aart , Hughes Michael
Published: July 2009

Berm formation and morphological development of the beach face have been observed during a neap–neap tidal cycle on the gently sloping and accreting beach at Vejers, Denmark. During the field campaign, an intertidal bar migrated onshore and stabilized as a berm on the foreshore. A new intertidal bar occurred on the lower beach face, migrated onshore on the rising tide and finally merged with the pre‐existing berm. As the tide continued to rise, the new berm translated further onshore as an intertidal bar to the uppermost part of the foreshore. The sediment transport during the berm transition was onshore directed in the upper swash and offshore directed in the lower swash. This berm development can be described through both the neap‐berm, ridge‐and‐runnel and berm‐ridge development concepts proposed by Hine (Sedimentology 1979; 26: 333–351), and all three stages were observed during only three tidal cycles. The main factors controlling this fast transformation were the gentle slope of the cross‐shore profile, rapid water level translation rates, substantial swash overtopping of the berm, and low infiltration rates. Despite the onshore migration of intertidal bars and berm formation, no net foreshore accretion took place during the field campaign. This was largely due to the formation of rip channels with strong rip currents cutting through the intertidal bars and the berm, which acted as a sediment drain in the profile. Copyright © 2009 John Wiley & Sons, Ltd.
Discontinuous Galerkin solution of preconditioned Euler equations for very low Mach number flows
Authors: Nigro A. , De Bartolo C. , Hartmann R. , Bassi F.
Published: July 2009

In this work we present a discontinuous Galerkin (DG) method designed to improve the accuracy and efficiency of the steady‐state solution at very low Mach number flows using an explicit scheme. The algorithm is based on a perturbed formulation of the compressible Euler equations and employs the preconditioning of both the instationary term of the governing equations and the dissipative term of the numerical flux function (full preconditioning approach).

The performance of the scheme is demonstrated by solving an inviscid flow past a NACA0012 airfoil at different very low Mach numbers using various degrees of polynomial approximation. We present numerical results computed with and without perturbed variables, which illustrate the influence of the cancellation errors on both the convergence and the accuracy of the DG solutions at low Mach numbers. Copyright © 2009 John Wiley & Sons, Ltd.
Practical evaluation of five partly discontinuous finite element pairs for the non‐conservative shallow water equations
Authors: Comblen Richard , Lambrechts Jonathan , Remacle Jean‐François , Legat Vincent
Published: July 2009

This paper provides a comparison of five finite element pairs for the shallow water equations. We consider continuous, discontinuous and partially discontinuous finite element formulations that are supposed to provide second‐order spatial accuracy. All of them rely on the same weak formulation, using Riemann solver to evaluate interface integrals. We define several asymptotic limit cases of the shallow water equations within their space of parameters. The idea is to develop a comparison of these numerical schemes in several relevant regimes of the subcritical shallow water flow. Finally, a new pair, using non‐conforming linear elements for both velocities and elevation (P−P), is presented, giving optimal rates of convergence in all test cases. P−P1 and P−P1 mixed formulations lack convergence for inviscid flows. P−P2 pair is more expensive but provides accurate results for all benchmarks. P−P provides an efficient option, except for inviscid Coriolis‐dominated flows, where a small lack of convergence is observed. Copyright © 2009 John Wiley & Sons, Ltd.
QALE‐FEM for modelling 3D overturning waves
Authors: Yan S. , Ma Q. W.
Published: July 2009

A further development of the QALE‐FEM (quasi‐arbitrary Lagrangian–Eulerian finite element method) based on a fully nonlinear potential theory is presented in this paper. This development enables the QALE‐FEM to deal with three‐dimensional (3D) overturning waves over complex seabeds, which have not been considered since the method was devised by the authors of this paper in their previous works (J. Comput. Phys.2006;212:52–72;J. Numer. Meth. Engng2009;78:713–756). In order to tackle challenges associated with 3D overturning waves, two new numerical techniques are suggested. They are the techniques for moving the mesh and for calculating the fluid velocity near overturning jets, respectively. The developed method is validated by comparing its numerical results with experimental data and results from other numerical methods available in the literature. Good agreement is achieved. The computational efficiency of this method is also investigated for this kind of wave, which shows that the QALE‐FEM can be many times faster than other methods based on the same theory. Furthermore, 3D overturning waves propagating over a non‐symmetrical seabed or multiple reefs are simulated using the method. Some of these results have not been found elsewhere to the best of our knowledge. Copyright © 2009 John Wiley & Sons, Ltd.
Prediction of entrance length and mass suction rate for a cylindrical sucking funnel
Authors: Mishra Dipti Prasad , Dash Sukanta K.
Published: July 2009

Conservation equations for mass, momentum and energy have been solved numerically for a cylindrical funnel with louvers (lateral openings on the side wall of the cylindrical funnel through which air can come into it) to compute the suction rate of air into the funnel. The nozzle placed centrally at the bottom of the cylinder ejects high‐velocity hot gaseous products so that atmospheric air gets sucked into the funnel. The objective of the work is to compute the ratio of the rate of mass suction to that of the mass ejected by the nozzle for different operating conditions and geometrical size of the funnel. From the computation it has been found that there exists optimum funnel diameter and optimum funnel height for which the mass suction is the highest. The protruding length of the nozzle into the funnel has almost no effect on the mass suction rate after a certain funnel height. The louvers opening area has a very high impact on the mass suction rate. The entrance length for such a sucking funnel is strikingly much lower compared with a simple cylindrical pipe having uniform flow at the inlet at same Reynolds number. A new correlation has been developed to propose the entrance length for a sucking pipe, the rate of mass suction into it and the exhaust plume temperature over a wide range of operating parameters that are normally encountered in a general funnel operations of naval or merchant ship. Copyright © 2009 John Wiley & Sons, Ltd.
Unstructured finite volume discretization of two‐dimensional depth‐averaged shallow water equations with porosity
Authors: Cea L. , Vázquez‐Cendón M. E.
Published: July 2009

This paper deals with the numerical discretization of two‐dimensional depth‐averaged models with porosity. The equations solved by these models are similar to the classic shallow water equations, but include additional terms to account for the effect of small‐scale impervious obstructions which are not resolved by the numerical mesh because their size is smaller or similar to the average mesh size. These small‐scale obstructions diminish the available storage volume on a given region, reduce the effective cross section for the water to flow, and increase the head losses due to additional drag forces and turbulence. In shallow water models with porosity these effects are modelled introducing an effective porosity parameter in the mass and momentum conservation equations, and including an additional drag source term in the momentum equations. This paper presents and compares two different numerical discretizations for the two‐dimensional shallow water equations with porosity, both of them are high‐order schemes. The numerical schemes proposed are well‐balanced, in the sense that they preserve naturally the exact hydrostatic solution without the need of high‐order corrections in the source terms. At the same time they are able to deal accurately with regions of zero porosity, where the water cannot flow. Several numerical test cases are used in order to verify the properties of the discretization schemes proposed. Copyright © 2009 John Wiley & Sons, Ltd.
Analysis of velocity equation of steady flow of a viscous incompressible fluid in channel with porous walls
Authors: Babaelahi M. , Ganji D. D. , Joneidi A. A.
Published: July 2009

Steady flow of a viscous incompressible fluid in a channel, driven by suction or injection of the fluid through the channel walls, is investigated. The velocity equation of this problem is reduced to nonlinear ordinary differential equation with two boundary conditions by appropriate transformation and convert the two‐point boundary‐value problem for the similarity function into an initial‐value problem in which the position of the upper channel. Then obtained differential equation is solved analytically using differential transformation method and compare with He's variational iteration method and numerical solution. These methods can be easily extended to other linear and nonlinear equations and so can be found widely applicable in engineering and sciences. Copyright © 2009 John Wiley & Sons, Ltd.
Alte Zeugnisse, neu ausgestellt
Authors: Stijnman Ad , Stäcker Thomas
Published: July 2009

Auf dem Weg zum „Virtuellen Kupferstichkabinett”︁: In Braunschweig und Wolfenbüttel werden mehr als 40 000 grafische Blätter digital zusammengeführt – zum Wohl von Forschung und Öffentlichkeit
Vertrauen verpflichtet
Authors: Kleiner Matthias
Published: July 2009

Nach dem „Ja”︁ zu Exzellenzinitiative, Forschungspakt und Hochschulpakt: Die Wissenschaft wird den Erwartungen der Politik gerecht werden
Eine Feier der besonderen Art
Authors: Finetti Marco
Published: July 2009

Warten auf die Politik, kritische Dankesworte aus Preisträgermund – die diesjährige Verleihung der Leibniz‐Preise hatte ihre ganz eigenen Akzente
Im Rhythmus der Vegetation
Authors: Wiegand Kerstin
Published: July 2009

Viele Savannen gelten als bedroht. Doch die riesigen Flächen, die ein Fünftel der Erde bedecken, haben ihre ganz eigene Dynamik: Die scheinbar unaufhaltsame Verbuschung ist tatsächlich nur ein natürliches Durchgangsstadium
Preserved executive function in high‐performing elderly is driven by large‐scale recruitment of prefrontal cortical mechanisms
Authors: De Sanctis Pierfilippo , Gomez‐Ramirez Manuel , Sehatpour Pejman , Wylie Glenn R. , Foxe John J.
Published: July 2009

High‐density electrical mapping of event‐related potentials was used to investigate the neural processes that permit some elderly subjects to preserve high levels of executive functioning. Two possibilities pertain: (1) high‐performance in elderly subjects is underpinned by similar processing mechanisms to those seen in young adults; that is, these individuals display minimal functional decay across the lifespan, or (2) preserved function relies on successfully recruiting and amplifying control processes to compensate for normal sensory‐perceptual decline with age. Fifteen young and nineteen elderly participants, the latter split into groups of high and low performers, regularly alternated between a letter and a number categorization task, switching between tasks every third trial (AAA‐BBB‐AAA…). This allowed for interrogation of performance during switch, repeat, and preparatory pre‐switch trials. Robust effects of age were observed in both frontal and parietal components of the task‐switching network. Greatest differences originated over prefrontal regions, with elderly subjects generating amplified, earlier, and more differentiated patterns of activity. This prefrontal amplification was evident only in high‐performing (HP) elderly, and was strongest on pre‐switch trials when participants prepared for an upcoming task‐switch. Analysis of the early transient and late sustained activity using topographic analyses and source localization collectively supported a unique and elaborated pattern of activity across frontal and parietal scalp in HP‐elderly, wholly different to that seen in both young and low‐performing elderly. On this basis, we propose that preserved executive function in HP‐elderly is driven by large‐scale recruitment and enhancement of prefrontal cortical mechanisms. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.
Gabapentin for the treatment of pain related to radiation‐induced mucositis in patients with head and neck tumors treated with intensity‐modulated radiation therapy
Authors: Bar Ad Voichita , Weinstein Gregory , Dutta Pinaki R. , Chalian Ara , Both Stefan , Quon Harry
Published: July 2009

Background.

This retrospective study evaluates the efficacy of gabapentin for the treatment of pain syndrome related to radiation‐induced mucositis in patients with head and neck tumors.

Methods.

Thirty cases of head and neck malignancies treated with radiotherapy were analyzed.

Results.

By using a median dose of 2700 mg/day of gabapentin, only 10% of patients required additional narcotic pain medications for adequate pain relief during the third and fourth week of treatment, despite grade 2 or higher mucositis present in 56% and 73% of the patients, respectively. Likewise, during the last weeks of intensity‐modulated radiation therapy (IMRT), only 35% of patients required additional narcotics for pain control, despite the presence of grade 2 or higher mucositis in 80% of cases.

Conclusions.

Gabapentin appears promising in reducing the need for narcotic pain medication for patients with head and neck malignancies treated with IMRT and should be further evaluated prospectively in controlled clinical trials. © 2009 Wiley Periodicals, Inc. Head Neck, 2010
Prospective trial to evaluate staged neck dissection or elective neck radiotherapy in patients with CT‐staged T1‐2 N0 squamous cell carcinoma of the oral tongue
Authors: Brennan Sinead , Corry June , Kleid Stephen , Porceddu Sandro , Yuen Kally , Rischin Danny , Peters Lester J.
Published: July 2009

Background

A prospective study was undertaken to evaluate a policy of selective, single‐modality elective neck treatment in T1‐2, node‐negative oral tongue squamous cell carcinoma.

Methods

Where the primary tumor showed 1 of the 4 key pathological criteria (greater than 7 mm of muscle invasion, less than 5 mm of resection margin, perineural or lymphovascular invasion), radiotherapy was delivered to the primary site and the at‐risk undissected neck. Otherwise patients underwent ipsilateral neck dissection within 4 weeks of initial resection. Prospective quality of life assessments were performed.

Results

The study was closed after accrual of 25 patients, because the high locoregional recurrence rate met early stopping criteria. With a median follow‐up of 3.4 years, the locoregional recurrence rate was 23%. The 4‐year overall and disease‐free survival rates were 71% and 64%, respectively.

Conclusion

The poor disease‐free survival reflects the need for better prognostic markers and more aggressive treatment in these patients. © 2009 Wiley Periodicals, Inc. Head Neck, 2010