bluuebunny/crossref_metadata_2025 huggingface dataset:
Permeability dependence study of the focused ultrasound‐induced blood–brain barrier opening at distinct pressures and microbubble diameters using DCE‐MRI
Authors: Vlachos Fotios , Tung Yao‐Sheng , Konofagou Elisa
Published: April 2011

Blood–brain barrier opening using focused ultrasound and microbubbles has been experimentally established as a noninvasive and localized brain drug delivery technique. In this study, the permeability of the opening is assessed in the murine hippocampus after the application of focused ultrasound at three different acoustic pressures and microbubble sizes. Using dynamic contrast‐enhanced MRI, the transfer rates were estimated, yielding permeability maps and quantitative Ktrans values for a predefined region of interest. The volume of blood–brain barrier opening according to the Ktrans maps was proportional to both the pressure and the microbubble diameter. A Ktrans plateau of ∼0.05 min−1 was reached at higher pressures (0.45 and 0.60 MPa) for the larger sized bubbles (4–5 and 6–8 μm), which was on the same order as the Ktrans of the epicranial muscle (no barrier). Smaller bubbles (1–2 μm) yielded significantly lower permeability values. A small percentage (7.5%) of mice showed signs of damage under histological examination, but no correlation with permeability was established. The assessment of the blood–brain barrier permeability properties and their dependence on both the pressure and the microbubble diameter suggests that Ktrans maps may constitute an in vivo tool for the quantification of the efficacy of the focused ultrasound‐induced blood–brain barrier opening. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Issues of discontinuity in the impulse residue function for deconvolution analysis of dynamic contrast‐enhanced MRI data
Authors: Koh T. S. , Cheong D. L. H. , Hou Z.
Published: April 2011

Recent dynamic contrast‐enhanced MRI studies using the adiabatic tissue homogeneity model have highlighted potential issues of difficulty in convergence during data‐fitting and reduced parameter precision, due to discontinuities in the adiabatic tissue homogeneity model. This study presents two solutions (an analytic approach and a discrete correction method) to such convergence problems and show that these problems can be attributed to an inaccurate approximation of the convolution integral based on the standard trapezoidal quadrature. It is further explained that such issues of discontinuity in the impulse residue function do not pertain only to the adiabatic tissue homogeneity model, but are generic to all tracer kinetic models, if the difference in bolus arrival time between the arterial input and tissue voxels were to be accounted for simultaneously during model‐fitting. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Computationally rapid method of estimating signal‐to‐noise ratio for phased array image reconstructions
Authors: Wiens Curtis N. , Kisch Shawn J. , Willig‐Onwuachi Jacob D. , McKenzie Charles A.
Published: April 2011

Measuring signal‐to‐noise ratio (SNR) for parallel MRI reconstructions is difficult due to spatially dependent noise amplification. Existing approaches for measuring parallel MRI SNR are limited because they are not applicable to all reconstructions, require significant computation time, or rely on repeated image acquisitions. A new SNR estimation approach is proposed, a hybrid of the repeated image acquisitions method detailed in the National Electrical Manufacturers Association (NEMA) standard and the Monte Carlo based pseudo‐multiple replica method, in which the difference between images reconstructed from the unaltered acquired data and that same data reconstructed after the addition of calibrated pseudo‐noise is used to estimate the noise in the parallel MRI image reconstruction. This new noise estimation method can be used to rapidly compute the pixel‐wise SNR of the image generated from any parallel MRI reconstruction of a single acquisition. SNR maps calculated with the new method are validated against existing SNR calculation techniques. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Spatially 2D‐selective RF excitations using the PROPELLER trajectory: Basic principles and application to MR spectroscopy of irregularly shaped single voxel
Authors: Busch Martin G. , Finsterbusch Jürgen
Published: April 2011

Spatially two‐dimensional selective radio frequency (2DRF) excitations are able to excite arbitrarily‐shaped profiles in their excitation plane and, hence, can be used to minimize partial volume effects in single‐voxel magnetic resonance spectroscopy. In this study, 2DRF excitations based on the PROPELLER trajectory which consists of blades of parallel lines that are rotated against each other, are presented. Because the k‐space center is covered with each segment, the trajectory yields a high signal efficiency which, e.g., is considerably improved compared to a segmented blipped‐planar approach. It is shown that a sampling density correction based on the PROPELLER trajectory's Voronoi diagram suppresses unwanted side excitations. Off‐resonance effects like chemical‐shift displacement artifacts, can be minimized by applying nonselective refocusing radio frequency pulses between the lines of a blade. With half‐Fourier segments, the 2DRF's echo time contribution can be shortened considerably. Thus, robust 2DRF excitations capable of exciting high‐resolution profiles at short echo times with high signal efficiency are obtained. Their applicability to MR spectroscopy of an arbitrarily‐shaped single voxel is demonstrated in a two‐bottle phantom and in the human brain in vivo on a 3 T whole‐body MR system. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Sodium and chloride channelopathies with myositis: Coincidence or connection?
Authors: Matthews Emma , Miller James A.L. , MacLeod Malcolm R. , Ironside James , Ambler Gareth , Labrum Robin , Sud Richa , Holton Janice L. , Hanna Michael G.
Published: April 2011

Introduction: A proximal myopathy develops in some patients with muscle channelopathies, but the causative molecular mechanisms are unknown. Methods: We reviewed retrospectively all clinical and muscle biopsy findings of 3 patients with channelopathy and additional myositis. Direct DNA sequencing was performed. Results: Pathogenic mutations were identified in each case. Biopsies demonstrated inflammatory infiltrates. Conclusions: Clinicians should consider muscle biopsy in channelopathy patients with severe myalgia and/or subacute weakness and accompanying elevated creatine kinase. Chance association of myositis and channelopathy is statistically unlikely. An alternative hypothesis suggests that inflammatory insults could contribute to myopathy in some patients. Muscle Nerve, 2011
Reliability of thermal quantitative sensory testing of the hand in a cohort of young, healthy adults
Authors: Moloney Niamh A. , Hall Toby M. , O'Sullivan Tomas C. , Doody Catherine M.
Published: April 2011

Introduction: The reliability of thermal quantitative sensory testing (QST) has yet to be fully established. In this study we investigated intra‐ and interrater reliability of thermal QST in a blinded manner. Methods: Two investigators recorded thermal detection and pain thresholds on the hand of 22 volunteers, twice on two occasions. Results were analyzed using descriptive statistics, intraclass correlation coefficients (ICCs), and coefficients of variation (CVs). Results: Mean intraindividual differences were small for all measures except cold pain thresholds. ICC values for intra‐ and interrater reliability were: cold detection, 0.27–0.55; warm detection, 0.33–0.69; and heat pain, 0.39–0.86. Cold pain yielded high ICC values (0.87–0.94), but also high CV (84.9–90.2%). Conclusions: In young, healthy adults, thermal detection and heat pain thresholds of the hand demonstrated good reliability for group comparisons and individual analyses. Cold pain threshold measures may be suitable for group comparisons, but a large variance in the data limits individual analyses. Muscle Nerve, 2011
Regulation of the calpain and ubiquitin‐proteasome systems in a canine model of muscular dystrophy
Authors: Wadosky Kristine M. , Li Luge , Rodríguez Jessica E. , Min Jin‐na , Bogan Dan , Gonzalez Jason , Patterson Cam , Kornegay Joe N. , Willis Monte
Published: April 2011

Introduction: Previous studies have tested the hypothesis that calpain and/or proteasome inhibition is beneficial in Duchenne muscular dystrophy, based largely on evidence that calpain and proteasome activities are enhanced in the mdx mouse. Methods: mRNA expression of ubiquitin‐proteasome and calpain system components were determined using real‐time polymerase chain reaction in skeletal muscle and heart in the golden retriever muscular dystrophy model. Similarly, calpain 1 and 2 and proteasome activities were determined using fluorometric activity assays. Results: We found that less than half of the muscles tested had increases in proteasome activity, and only half had increased calpain activity. In addition, transcriptional regulation of the ubiquitin‐proteasome system was most pronounced in the heart, where numerous components were significantly decreased. Conclusion: This study illustrates the diversity of expression and activities of the ubiquitin‐proteasome and calpain systems, which may lead to unexpected consequences in response to pharmacological inhibition. Muscle Nerve, 2011
On bounded solutions of transport equation solved with a spectral method
Authors: Martin Olga
Published: April 2011

In this article, a spectral method accompanied by finite difference method has been proposed for solving a boundary value problem that accompanies a stationary transport equation. We also prove that the solution is bounded by a value that depends of the source function. The accuracy and computational efficiency of the proposed method are verified with the help of a numerical example. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2012
Higher dose imatinib for children with de novo chronic phase chronic myelogenous leukemia: A report from the Children's Oncology Group
Authors: Champagne Martin A. , Fu Cecilia H. , Chang Myron , Chen Helen , Gerbing Robert B. , Alonzo Todd A. , Cooley Linda D. , Heerema Nyla A. , Oehler Vivian , Wood Charlotte , French Mary Ellen , Arceci Robert J. , Smith Franklin O. , Bernstein Mark L.
Published: April 2011

Purpose

To determine the efficacy of imatinib in children with newly diagnosed chronic phase (CP) chronic myelogenous leukemia (CML).

Methods

This was an open label, multi‐center phase II clinical trial. Courses were defined as consecutive 28‐day intervals. Oral imatinib was administered daily at 340 mg/m2 without interruption in the absence of toxicity.

Results

Fifty‐one children received 978 28‐day courses of imatinib. The most common toxicities encountered were hematologic. Forty‐one patients (80%) achieved a complete hematologic response by the end of course 2. Nineteen children (38%) obtained a complete cytogenetic response (CCyR) at the end of course 3. Overall, 72% achieved CCyR at a median time of 5.6 months. The rate of complete molecular response (>3 log reduction) was 27%. Progression‐free and overall survival at 3 years were 72% ± 6.4% and 92% ± 3.9%, respectively.

Conclusions

Daily oral imatinib at a dose of 340 mg/m2 is well tolerated in children. In addition, imatinib therapy is effective in inducing a high percent of hematologic, cytogenetic and molecular responses, comparable to adults with CML. (This study was registered at ClinicalTrials.gov under identifier NCT00030394.). Pediatr Blood Cancer 2011;57:56–62. © 2011 Wiley‐Liss, Inc.
Extensive central nervous system involvement in optic pathway gliomas in neurofibromatosis type 1
Authors: Shaikh Furqan , Johnston Donna , Michaud Jean , Hurteau Julie , Vassilyadi Michael , Keene Daniel
Published: April 2011

Optic pathway gliomas (OPG) in neurofibromatosis type 1 (NF1) usually remain localized to the anterior visual pathway. However, a small number can demonstrate widespread dissemination. We describe three children with NF1 OPGs and extensive central nervous system involvement. In one case, a postmortem examination revealed tumor cells extending continuously from the optic nerves to the conus medullaris. This is the most widespread NF1 OPG reported in the literature. We suggest that rapid visual deterioration in the absence of radiographic changes or increased intracranial pressure can be caused by increasing tumor infiltration within the central nervous system. Pediatr Blood Cancer 2011; 57: 688–690. © 2011 Wiley‐Liss, Inc.
A Novel Protocol for the Preparation of Sodium Tanshinone Sulphonates by Direct Ultrasound‐assisted Sulphonation of the Crude Extract of the Roots of Salvia miltiorrhiza Bunge and Following Counter‐current Chromatography Purification
Authors: Zeng Liping , Wu Dingfang , Wu Shihua
Published: April 2011

Introduction

Sodium tanshinone sulphonates are water‐soluble derivatives of tanshinones originated from Tanshen (or Danshen, Salvia miltiorrhiza Bunge), a famous Traditional Chinese Medicine, which have potent biological activities, especially in the treatment of cardiovascular disorders. However, the classical preparation processes of sodium tanshinone sulphonates often involve multiple time‐ and solvent‐consuming steps after purification of tanshinones, resulting in relatively low yields.

Objective

To develop a simple protocol for direct preparation of sodium tanshinone sulphonates from the complex crude extract of the roots of S. miltiorrhiza without pre‐purification of tanshinones.

Methodology

The 100 mg crude tanshinone extract of S. miltiorrhiza was first sulphonated in a ultrasound bath with glacial acetic acid, acetic anhydride and concentrated sulphuric acid for 20 min, and then subjected to counter‐current chromatography (CCC) separation using a optimum two‐phase solvent system composed of n‐hexane:ethylacetate:ethanol:5% sodium chloride aqueous solution (1:8:4:10, v/v). Based on the UV detection and HPLC analyses, the sulphonated fractions were collected.

Result

Sodium tanshinone IIA sulphonate (7.1 mg) and sodium tanshinone I sulphonate (2.8 mg) with over 95% purity were obtained successfully for the first time by ultrasound‐assisted sulphonation and following CCC purification.

Conclusion

The study has shown that the method combining ultrasound‐assisted sulphonation and CCC purification is an efficient way to prepare tanshinone sulphonates without pre‐purification of tanshinones from the complex extracts of Tanshen, and can be explored as a new protocol for wide natural product modification directly from a crude complex extracts without pre‐purification. Copyright © 2011 John Wiley & Sons, Ltd.
Differences Among Epilobium and Hypericum Species Revealed by four IR Spectroscopy Modes: Transmission, KBr Tablet, Diffuse Reflectance and ATR
Authors: Kokalj Meta , Kolar Jana , Trafela Tanja , Kreft Samo
Published: April 2011

Introduction

Quality control of dried plant material in assessments of suitability of herbal medicinal products is of extreme importance. Commonly used procedures for identification of species are time consuming and expensive. The development of multivariate statistical methods has enabled application of vibrational spectroscopy for establishing plant species membership.

Objective

To determine which infrared spectroscopy mode gives most informative spectra for plant species identification.

Methodology

Different modes of infrared spectroscopy were applied for investigation of differences among Epilobium and Hypericum species: diffuse reflectance (DR), attenuated total reflectance (ATR), direct transmission of whole leaves and KBr tablet transmission with comminuted leaves. The same chemometrical methods were applied to all spectra. The informative wave numbers were chosen by one‐way analysis of variance. Afterwards the colinearity was reduced with principal component analysis. In the final step the species identification was determined with discriminant analysis.

Results

Transmission and diffuse reflectance mode did not give satisfactory results. Best results for discrimination among Epilobium species were obtained with ATR mode (98%), while best results for Hypericum species were obtained with KBr transmission mode (97%). This might be explained by the morphological properties of the two genera. Epilobium species differ in distribution and morphology of trichomes on the surface of the leaves. Hypericum species differ in structures and secondary metabolites in the interior of the leaves.

Conclusion

For best results in using infrared spectroscopy for plant species identification in quality control, the morphological properties of plant material should be taken into consideration. Copyright © 2011 John Wiley & Sons, Ltd.
Risk Management Affecting IS/IT Project Success through Communicative Action
Authors: de Bakker Karel , Boonstra Albert , Wortmann Hans
Published: April 2011

Project risk management is defined in the literature as being instrumental action based on rational problem solving. Research indicates limited positive effects of an exclusive focus of instrumental action on project success. This article proposes to extend this instrumental view through communicative action. This theoretical broadening was explored by interviewing project stakeholders about project success and risk management application. Analysis demonstrates stakeholders deliberately use risk management to convey messages to others, with the aim of influencing their behavior, synchronizing their perception, and making them aware of the context and their responsibilities. Stakeholders perceive these effects as contributing to project success.
Capnography in spontaneously breathing preterm infants with bronchopulmonary dysplasia
Authors: Lopez Emmanuel , Mathlouthi Jihene , Lescure Sandra , Krauss Baruch , Jarreau Pierre‐Henri , Moriette Guy
Published: April 2011

Background

In adult patients with chronic obstructive pulmonary disease, there is a gradient between end‐tidal carbon dioxide (EtCO2) and arterial carbon dioxide pressure (PaCO2), and the slope of the ascending phase of the capnogram is decreased due to obstruction. Corresponding data are lacking in infants with bronchopulmonary dysplasia (BPD).

Objectives

To compare PCO2–EtCO2 gradient and capnogram shape in two groups of spontaneously breathing preterm subjects: infants with BPD and infants without respiratory disease (controls).

Material and Methods

Capnography was performed at 36 weeks postmenstrual age in 20 infants (12 BPD with oxygen dependency, 8 controls). Respiratory rate and the components of the respiratory cycle were measured. The PCO2–EtCO2 gradient was calculated using EtCO2 values and simultaneously sampled capillary values (PcCO2). Capnograms were compared between groups.

Results

In BPD subjects, respiratory rate was increased (60 ± 16 bpm vs 43 ± 16 bpm, P = 0.009); a widened PcCO2–EtCO2 gradient was observed (13 ± 4 mmHg vs 0 ± 7 mmHg, P = 0.0013); the ascending phase of the capnogram was not decreased, whereas the initial inspiratory phase was prolonged (0.32 ± 0.05 vs 0.24 ± 0.04, P = 0.001).

Conclusions

Compared with healthy infants, a higher PcCO2–EtCO2 gradient was observed in infants with BPD, suggesting that ventilation–perfusion mismatch may be present in these infants. The capnogram did not exhibit the characteristic shape of airway obstruction. Pediatr. Pulmonol. 2011; 46:896–902. © 2011 Wiley‐Liss, Inc.
Lung function changes in asthmatic children treated with HFA‐BDP
Authors: Eid Nemr , Morton Ronald
Published: April 2011

Study Objectives

Asthma guidelines suggest that normal or near normal lung function should be one of the goals for good asthma control. Therefore, children with chronic persistent asthma and reduced peripheral airway function were assessed after the replacement of conventional inhaled corticosteroids (ICS) with an extrafine aerosol formulation, hydrofluoroalkane–134a beclomethoasone diproprionate (HFA‐BDP).

Design and Setting

Lung function and clinical details were studied in children with moderate persistent asthma who regularly attended the pediatric pulmonary outpatient clinic at Kosair Children's Hospital, Louisville, Kentucky, USA.

Subjects

A total of 20 children, 7 girls and 13 boys, with stable asthma but reduced forced expiratory flows between 25% and 75% of vital capacity (FEF25–75) were included in the study.

Intervention

After the initial assessment, each subject was switched from conventional ICS to HFA‐BDP. All other medications remained the same. Reassessment of lung function and clinical status was performed at least 3 weeks after the intervention.

Results

FEF25–75 increased from a mean of 50.75% to 68.85% predicted (P < 0.001). Forced expiratory volume in 1 sec (FEV1) also increased significantly from 84.6% to 93.8% predicted (P = 0.001). No changes asthma symptoms were observed.

Conclusion

Compared to conventional ICS, the use of HFA‐BDP in asthmatic children significantly improves airflow in both the large and the peripheral airways without loss of asthma control. Pediatr. Pulmonol. 2011; 46:837–841. © 2011 Wiley‐Liss, Inc.
Obstructive sleep apnea in poorly controlled asthmatic children: Effect of adenotonsillectomy
Authors: Kheirandish‐Gozal Leila , Dayyat Ehab A. , Eid Nemr S. , Morton Ronald L. , Gozal David
Published: April 2011

Background

Asthma and obstructive sleep apnea (OSA) in children share multiple epidemiological risk factors and the prevalence of snoring is higher in asthmatic children, suggesting that the latter may be at increased risk for OSA. Since both asthma and OSA are inflammatory disorders, we hypothesized that polysomnographically demonstrated OSA would be more frequent among poorly controlled asthmatics (PCA), and that treatment of OSA, if present, would ameliorate the frequency of acute asthmatic exacerbations (AAE).

Methods

Children with PCA were referred for an overnight sleep study, and adenotonsillectomy (tonsillectomy and adenoidectomy, T&A) was performed if OSA was present. Frequency of asthma symptoms and exacerbations were compared.

Results

Ninety‐two PCA children, ages 3–10 years, with a mean frequency of AAE of 3.4 ± 0.4/year were prospectively referred for a sleep study. OSA (i.e., AHI > 5/hrTST) was present in 58 patients (63.0%; OR: 40.9, 12.9–144.1, P < 0.000001 compared to the prevalence of OSA in a non‐asthmatic population). Information at 1‐year follow‐up was available for 35 PCA children after T&A. The annual frequency of AAE, rescue inhaled use, and asthma symptoms in this sub‐group decreased compared to no changes in the group without OSA.

Conclusions

The prevalence of OSA is markedly increased among PCA children and treatment of OSA appears to be associated with substantial improvements in the severity of the underlying asthmatic condition. Pediatr. Pulmonol. 2011; 46:913–918. © 2011 Wiley‐Liss, Inc.
Crystal structure of the Leishmania major MIX protein: A scaffold protein that mediates protein–protein interactions
Authors: Gorman Michael A. , Uboldi Alex D. , Walsh Peter J. , Tan Kher Shing , Hansen Guido , Huyton Trevor , Ji Hong , Curtis Joan , Kedzierski Lukasz , Papenfuss Anthony T. , Dogovski Con , Perugini Matthew A. , Simpson Richard J. , Handman Emanuela , Parker Michael W.
Published: April 2011

Infection by Leishmania and Trypanosoma causes severe disease and can be fatal. The reduced effectiveness of current treatments is largely due to drug resistance, hence the urgent need to develop new drugs, preferably against novel targets. We have recently identified a mitochondrial membrane‐anchored protein, designated MIX, which occurs exclusively in these parasites and is essential for virulence. We have determined the crystal structure of Leishmania major MIX to a resolution of 2.4 Å. MIX forms an all α‐helical fold comprising seven α‐helices that fold into a single domain. The distribution of helices is similar to a number of scaffold proteins, namely HEAT repeats, 14‐3‐3, and tetratricopeptide repeat proteins, suggesting that MIX mediates protein–protein interactions. Accordingly, using copurification and mass spectroscopy we were able to identify several proteins that may interact with MIX in vivo. Being parasite specific, MIX is a promising new drug target and, thus, the structure and potential interacting partners provide a basis for structure‐guided drug discovery.
Design of Deinococcus radiodurans thioredoxin reductase with altered thioredoxin specificity using computational alanine mutagenesis
Authors: Obiero Josiah , Sanders David A.R.
Published: April 2011

In this study, the X‐ray crystal structure of the complex between Escherichia coli thioredoxin reductase (EC TrxR) and its substrate thioredoxin (Trx) was used as a guide to design a Deinococcus radiodurans TrxR (DR TrxR) mutant with altered Trx specificity. Previous studies have shown that TrxRs have higher affinity for cognate Trxs (same species) than that for Trxs from different species. Computational alanine scanning mutagenesis and visual inspection of the EC TrxR–Trx interface suggested that only four residues (F81, R130, F141, and F142) account for the majority of the EC TrxR–Trx interface stability. Individual replacement of equivalent residues in DR TrxR (M84, K137, F148, and F149) with alanine resulted in drastic changes in binding affinity, confirming that the four residues account for most of TrxR–Trx interface stability. When M84 and K137 were changed to match equivalent EC TrxR residues (K137R and M84F), the DR TrxR substrate specificity was altered from its own Trx to that of EC Trx. The results suggest that a small subset of the TrxR–Trx interface residues is responsible for the majority of Trx binding affinity and species‐specific recognition.
Modeling dispersion and deposition of smoke generated from chemical fires
Authors: Khajehnajafi Shahryar , Pourdarvish Reza , Shah Hardik
Published: April 2011

Smoke is a mixture of toxic gases and suspended particulate matter of solids and liquids that evolves from a fire of flammable materials. This article presents real‐time consequence modeling to track the concentration of individual species in smoke as well as its soot deposition. In the modeling process presented, the burning rate or vapor mass is fed into a combustion model in which the combustion of products has been identified and quantified along with the temperature of the fire. The output of the combustion model is the smoke that will be dispersed into the ambient. The fire geometry, which depends on the type of fire (e.g., pool or flare), is identified. A dispersion model with the capability of determining particulate deposition is then used for tracking the smoke plume. The combustion model provides the composition of the toxic species present in the smoke: carbon monoxide, halogen acids, organic and inorganic irritants, and soot, and their quantities as the air‐to fuel ratio is changed. The end product is an excellent what‐if analysis tool for responders. For example, it provides the ability to determine whether to ignite or when to ignite a flammable, toxic release by comparing their consequences. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
A Proposed Tool to Determine Dynamic Load Distribution between Corrugated Boxes
Authors: Jamialahmadi Arsalan , Trost Thomas , Östlund Sören
Published: April 2011

This paper summarizes the dynamic analysis of the interaction of corrugated boxes in transport using a pressure‐mapping system. The dynamic contact forces on the contact area between boxes in both vertical and horizontal directions were measured, and the position of the instantaneous centre of force was traced, from which the pitch motion of boxes relative to each other was studied. The level‐crossing diagrams of the contact forces show a Rayleigh distribution for the vertical contact and a Gaussian distribution for the horizontal contacts. The contact force and acceleration power spectral density from accelerometers and pressure‐mapping system were compared.

The results show that a pressure‐mapping system is an interesting tool for the analysis of the dynamic performance of systems of corrugated boxes under different stacking and loading conditions. Copyright © 2011 John Wiley & Sons, Ltd.
Stereo‐dynamics of the F + HCl → HF + Cl reaction
Authors: Yin Shuhui , Guo Mingxing , Li Lei , Zhang Yinghui , Li Xiangping
Published: April 2011

We present a quasi‐classical trajectory (QCT) study on product polarization for the reaction F(2P) + HCl(v = 0, j = 0) → HF + Cl(2P) on a recently computed 12
A′ ground‐state surface reported by Deskevich et al. J Chem Phys, 2006, 124, 224303. Four polarization dependent generalized differential cross‐sections (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt), and (2π/σ)(dσ21−/dωt) were calculated in the center‐of‐mass frame at four different collision energies. The obtained P(θr), P(ϕr), and P(θr, ϕr), which denote respectively the distribution of angles between k and j′, the distribution of dihedral angle denoting k‐k′‐j′ correlation and the angular distribution of product rotational vectors in the form of polar plots, indicate that the degree of rotational alignment of the product HF molecule is strong and the degree of the rotational alignment decreases as collision energy increases. The product rotational angular momentum vector j′ is not only aligned, but also oriented along the y‐axis, and the molecular rotation of the product prefers an in‐plane reaction mechanism rather than the out‐of‐plane mechanism. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Charge transport and optical properties of discotic liquid crystalline molecules THDDP and substituted THDP
Authors: Saranya Govindarajan , Santhanamoorthi Nachimuthu , Kolandaivel Ponmalai , Senthilkumar Kittusamy
Published: April 2011

The theoretical investigations have been carried out on the discotic liquid crystalline molecules, 2,3,6,7‐tetrakis‐hexyloxy‐9,16‐diaza‐dibenzo[a,c]phenazine (THDDP) and different substituted 2,3,6,7‐tetrakis‐hexyloxy‐dibenzo[a,c]phenazine (THDP) to study their charge transport and optical properties. The key parameters of charge transport such as charge transfer integrals and site energies have been calculated from the matrix elements of Kohn‐Sham Hamiltonian. The reorganization energy for the presence of excess charge and the rate of charge transfer calculated from Marcus theory have been used to find the mobility of the charge carrier in the studied molecules. The results show that the substitution and stacking angle change strongly affect the charge carrier mobility in π‐stacked THDDP and substituted THDP molecules. Molecular dynamics simulations have been performed to find the most favorable conformation. The time‐dependent density functional theory (TDDFT) calculations reveal that for these molecules the different substitutions does not alter the main features of optical properties and the molecules may be used as blue light emitters. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
A DFT study on the mechanisms for the cycloaddition reactions between 1‐Aza‐2‐azoniaallene cations and carbodiimides
Authors: Wang Jing‐Mei , Li Zhi‐Minhg , Wang Quan‐Rui , Tao Feng‐Gang
Published: April 2011

The mechanisms of the title reactions between 1‐aza‐2‐azoniaallene cations and carbodiimides in the gas phase have been examined using the Becke‐3‐parameter‐Lee‐Yang‐Parr (B3LYP) at 6‐31++G** level. The theoretical results revealed that the reaction is a domino reaction that comprises two consecutive reactions: an ionic [3+2] cycloaddition reaction between 1‐aza‐2‐azoniallene cation and carbodiimide to yield the cycloadduct3and then a [1,2]‐shift to yield the thermodynamically more stable adduct4. Both stepwise and concerted pathways are accessible in the first cycloaddition in the model reaction. The activation barriers of them are almost equivalent. For the [1,2]‐shift reactions, both of the electron‐withdrawing chlorine substituent and the electron‐releasing methyl substituent on the 1‐aza‐2‐azoniaallene cation can facilitate the reaction but have little effects when substituted in the carbodiimide moiety. The model reaction has also been investigated at the QCISD (quadratic configuration interaction using single and double substitutions)/6‐31++G** and CCSD(T) (coupled cluster calculations with single and double excitations and a perturbative estimate of triple contributions calculations)/6‐31++G** levels as well as by the density functional theory. In addition, solvent effects with the isodensity‐surface polarized continuum model are also reported for all the reactions. In solvent dichloromethane, the cycloadducts of all the reactions, except model reaction and reaction d, were obtained from reactants directly as the result of the solvent effect. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Variational approach to the confined hydrogen atom with a moving nucleus
Authors: Fernández F. M. , Aquino N. , Flores‐Riveros A.
Published: April 2011

We calculate the ground‐state energy and other physical properties of the hydrogen atom inside a spherical box with an impenetrable wall. We apply the variational method and show that the total, kinetic, and potential energies for the moving nucleus model are greater than those for the case in which the nucleus is clamped at the box center. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
DFT study of the gas‐phase thermal decomposition kinetics of 2‐ethoxypyridine into 2‐pyridone
Authors: Marquez Edgar , Cordova Tania , Chuchani Gabriel
Published: April 2011

The mechanism of the gas‐phase elimination kinetics of 2‐ethoxypyridine has been studied through the electronic structure calculations using density functional methods: B3LYP/6‐31G(d,p), B3LYP/6‐31++G(d,p), B3PW91/6‐31G(d,p), B3PW91/6‐31++G(d,p), MPW1PW91/6‐31G(d,p), MPW1PW91/6‐31++G(d,p), PBEPBE/6‐31G(d,p), PBEPBE/6‐31++G(d,p), PBE1PBE1/6‐31G(d,p), and PBE1PBE1/6‐31++G(d,p). The elimination reaction of 2‐ethoxypyridine occurs through a six‐centered transition state geometry involving the pyridine nitrogen, the substituted carbon of the aromatic ring, the ethoxy oxygen, two carbons of the ethoxy group, and a hydrogen atom, which migrates from the ethoxy group to the nitrogen to give 2‐pyridone and ethylene. The reaction mechanism appears to occur with the participation of π‐electrons, similar to alkyl vinyl ether elimination reaction, with simultaneous ethylene formation and hydrogen migration to the pyridine nitrogen producing 2‐pyridone. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Conformational dependence of the electronic coupling in guanine–tryptophan complexes: A DFT study
Authors: Butchosa C. , Simon S. , Voityuk A. A.
Published: April 2011

Radical cation states (electron holes) generated in DNA lead to mutagenic effects. In DNA–protein complexes, the holes can migrate from DNA to aromatic amino acid residues preventing the formation of the oxidative lesions. The efficiency of hole transfer (HT) may significantly depend on the arrangement of redox sites. This dependence is mainly determined by sensitivity of the electronic coupling of donor and acceptor to structural changes. Based on DFT calculations of a number of guanine–tryptophan (G–Trp) complexes, we explore the conformational dependence of HT electronic coupling in this dyad. Stacked and T‐shaped structures are considered. The electronic coupling in the system is shown to be responsive to the mutual arrangement of G and Trp. Although in most cases the probability of HT in T‐shaped conformations is predicted to be lower than in π stacks, several T‐type structures are found where HT should be very efficient. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem 112:1838–1843, 2012
Solvent effects on SN2 reaction between substituted benzyl chloride and chloride ion
Authors: Ebrahimi A. , Habibi Khorassani M. , Doosti M.
Published: April 2011

The effects of solvent on SN2 reaction between some substituted benzyl chlorides and chloride ion have been investigated by DFT and ab initio methods using the polarizabale continuum model. The activation energies are higher in the solution media relative to the gas phase and grow by the increase in the dielectric constant of solvent. The complexation energies in solution media are smaller than those in the gas phase and reduce with increasing the dielectric constant. The energy data are in good agreement with the geometrical parameters and substituent constants. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
An HMM approach for optimal investment of an insurer
Authors: Elliott Robert J. , Siu Tak Kuen
Published: April 2011

In this paper, we introduce a Hidden Markov Model (HMM) for studying an optimal investment problem of an insurer when model uncertainty is present. More specifically, the financial price and insurance risk processes are modulated by a continuous‐time, finite‐state, hidden Markov chain. The states of the chain represent different modes of the model. The HMM approach is viewed as a ‘dynamic’ version of the Bayesian approach to model uncertainty. The optimal investment problem is formulated as a stochastic optimal control problem with partial observations. The innovations approach in the filtering theory is then used to transform the problem into one with complete observations. New robust filters of the chain and estimates of key parameters are derived. We discuss the optimal investment problem using the Hamilton–Jacobi–Bellman (HJB) dynamic programming approach and derive a closed‐form solution in the case of an exponential utility and zero interest rate. Copyright © 2011 John Wiley & Sons, Ltd.
Asymptotic and robust stability of T‐S fuzzy genetic regulatory networks with time‐varying delays
Authors: Liu Jinliang , Yue Dong
Published: April 2011

In this paper, we propose and investigate a new general model of fuzzy genetic regulatory networks described by the Takagi–Sugeno (T‐S) fuzzy model with time‐varying delays. By using a Lyapunov functional approach and linear matrix inequality (LMI) techniques, the stability criteria for the delayed fuzzy genetic regulatory networks are expressed as a set of LMIs, which can be solved numerically by LMI toolbox in Matlab. Two fuzzy genetic network example are given to verify the effectiveness and applicability of the proposed approach. Copyright © 2011 John Wiley & Sons, Ltd.
Spatially adaptive semi‐supervised learning with Gaussian processes for hyperspectral data analysis
Authors: Jun Goo , Ghosh Joydeep
Published: April 2011

This paper presents a semi‐supervised learning algorithm called Gaussian process expectation‐maximization (GP‐EM), for classification of landcover based on hyperspectral data analysis. Model parameters for each land cover class are first estimated by a supervised algorithm using Gaussian process regressions to find spatially adaptive parameters, and the estimated parameters are then used to initialize a spatially adaptive mixture‐of‐Gaussians model. The mixture model is updated by expectation‐maximization iterations using the unlabeled data, and the spatially adaptive parameters for unlabeled instances are obtained by Gaussian process regressions with soft assignments. Spatially and temporally distant hyperspectral images taken from the Botswana area by the NASA EO‐1 satellite are used for experiments. Detailed empirical evaluations show that the proposed framework performs significantly better than all previously reported results by a wide variety of alternative approaches and algorithms on the same datasets. © 2011 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 4: 358–371, 2011
Activation of extracellular signal‐regulated kinase is critical for the discriminative stimulus effects induced by U‐50,488H
Authors: Yoshizawa Kazumi , Narita Minoru , Saeki Mai , Narita Michiko , Isotani Kana , Horiuchi Hiroshi , Imai Satoshi , Kuzumaki Naoko , Suzuki Tsutomu
Published: April 2011

We previously demonstrated that the discriminative stimulus effects of the κ‐opioid receptor agonist U‐50,488H were associated with its aversive effects in rats. However, its molecular signaling mechanisms are not fully understood. The aim of this study was to investigate the intracellular signaling that plays a role in mediating the discriminative stimulus effect induced by U‐50,488H. To better understand the involvement of molecular signaling mechanisms in the discriminative stimulus effects of U‐50,488H, rats were subjected to a drug discrimination paradigm, and levels of immunoreactivity and mRNA expression were determined in these rats. Although U‐50,488H‐trained rats did not show changes in the mRNA expression of typical dopamine (DA) receptors, NMDA receptor subunits, or transcriptional activators, there were remarkable changes in the levels of immunoreactivity of several phosphorylated protein kinases. The levels of immunoreactivity of phosphorylated p38 MAPK and phosphorylated calcium/calmodulin‐dependent protein kinase II (CaMKII) were significantly increased in the nucleus accumbens and amygdala in lever‐press, yoked and discrimination groups compared to a naive group. Furthermore, the level of phosphorylated cAMP response element‐binding protein was also increased in both the discrimination and yoked groups. In contrast, the immunoreactivity of phosphorylated extracellular signaling‐regulated kinase (ERK 1/2) was specifically increased in the discrimination group. These results suggest that the ERK signaling pathway in the nucleus accumbens and amygdala may be critical for the expression of the discriminative stimulus effects of U‐50,488H. Synapse, 2011. © 2011 Wiley‐Liss, Inc.
Apamin induces plastic changes in hippocampal neurons in senile Sprague–Dawley rats
Authors: Romero‐Curiel Alejandra , López‐Carpinteyro Diana , Gamboa Citlalli , De la cruz Fidel , Zamudio Sergio , Flores Gonzalo
Published: April 2011

Apamin is a neurotoxin extracted from honey bee venom and is a selective blocker of small‐conductance Ca2+‐activated K+ channels (SK). Several behavioral and electrophysiological studies indicate that SK‐blockade by apamin may enhance neuron excitability, synaptic plasticity, and long‐term potentiation in the CA1 hippocampal region, and, for that reason, apamin has been proposed as a therapeutic agent in Alzheimer's disease treatment. However, the dendritic morphological mechanisms implied in such enhancement are unknown. In the present work, Golgi–Cox stain protocol and Sholl analysis were used to study the effect of apamin on the dendritic morphology of pyramidal neurons from hippocampus and the prefrontal cortex as well as on the medium spiny neurons from the nucleus accumbens and granule cells from the dentate gyrus (DG) of the hippocampus. We found that only granule cells from the DG and pyramidal neurons from dorsal and ventral hippocampus were altered in senile rats injected with apamin. Our research suggests that apamin may increase the dendritic morphology in the hippocampus, which could be related to the neuronal excitability and synaptic plasticity enhancement induced by apamin. Synapse 2011. © 2011 Wiley‐Liss, Inc.
Lack of association between synapsin II (SYN2) gene polymorphism and susceptibility epilepsy: A case–control study and meta‐analysis
Authors: Haerian Batoul Sadat , Lim Kheng Seang , Tan Hui Jan , Wong Chee Piau , Wong Sau Wei , Tan Chong Tin , Raymond Azman Ali , Mohamed Zahurin
Published: April 2011

Objective: The SYN2 rs3773364 A>G polymorphism has been proposed to be involved in susceptibility to epilepsy, but research results have been inconclusive. The aim of this study was to investigate the association between the SYN2 rs3773364 A>G polymorphism and susceptibility against epilepsy in a case–control study and a meta‐analysis. Methods: The SYN2 rs3773364 A>G polymorphism was successfully genotyped in 1182 samples (618 epilepsy patients) of Chinese, Indian, and Malay ethnicities. Meta‐analysis of the related studies, including this case–control study, was performed under alternative genetic models. Results: Data from the case–control study indicated no allelic and genotypic association of this locus with susceptibility to epilepsy in the tri‐ethnic Malaysian population. Similar finding was obtained by stratified analysis by epilepsy syndrome for idiopathic epilepsy. These results were verified by meta‐analysis of the related pooled data. Conclusions: Our study indicated that SYN2 rs3773364 A>G polymorphism is not a risk factor for susceptibility to epilepsy. Synapse 2011. © 2011 Wiley‐Liss, Inc.
Duration of persistent abnormal ductus venosus flow and its impact on perinatal outcome in fetal growth restriction
Authors: Turan O. M. , Turan S. , Berg C. , Gembruch U. , Nicolaides K. H. , Harman C. R. , Baschat A. A.
Published: April 2011

Objective

To study if the duration of individual Doppler abnormalities is an independent predictor of adverse outcome in fetal growth restriction (FGR) caused by placental dysfunction.

Methods

This was a secondary analysis of patients with FGR (abdominal circumference < 5th percentile and umbilical artery (UA) pulsatility index (PI) elevation) who had at least three examinations before delivery. Days of duration of absent/reversed UA end‐diastolic velocity (UA‐AREDV), low middle cerebral artery PI (brain sparing), ductus venosus (DV) and umbilical vein Doppler abnormalities were related to stillbirth, major neonatal morbidity and intact survival.

Results

One hundred and seventy‐seven study participants underwent a total of 1069 examinations. The duration of an absent/reversed a‐wave in the DV (DV‐RAV) was significantly higher in stillbirths (median, 6 days) compared with intact survivors and those with major morbidity (median, 0 days for both; P = 0.006 and P = 0.001, respectively). Duration of brain sparing was also longer in stillbirth cases compared with intact survivors (median, 19 days vs. 9 days, P = 0.02). Stepwise multinomial logistic regression showed that gestational age at delivery was a significant codeterminant of outcome for all arterial Doppler abnormalities when the DV a‐wave was antegrade. However, when present, the duration of DV‐RAV was the only contributor to stillbirth (probability of stillbirth = 1/(1 + exp − (interval to delivery × 1.03 − 2.28)), r2 = 0.73). Receiver–operating characteristics curve statistics showed that a DV‐RAV for > 7 days predicted stillbirth (100% sensitivity, 80% specificity, likelihood ratio = 5.0, P < 0.0001). In contrast, neither neonatal death nor neonatal morbidity was predicted by the days of persistent DV‐RAV.

Conclusions

The duration of absent or reversed flow during atrial systole in the DV is a strong predictor of stillbirth that is independent of gestational age. While prematurity remains the strongest predictor of neonatal risks it is unlikely that pregnancy can be prolonged by more than 1 week in this setting. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
A framework to determine optimal offshore grid structures for wind power integration and power exchange
Authors: Trötscher Thomas , Korpås Magnus
Published: April 2011

This paper presents a framework to find optimal offshore grid expansions using a transportation model of the power grid. The method extends the standard mixed‐integer linear programming approach to the solution of the transmission expansion planning problem to account for fluctuations in wind power generation and load; this makes the method especially suited to identify optimal transnational offshore high‐voltage direct current grid structures for the integration of large amounts of offshore wind power. The applicability of the method is demonstrated by a case study of the North Sea region. Copyright © 2011 John Wiley & Sons, Ltd.