bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Polyketides Isolated from Botryosphaeria australis Strain ZJ12‐1A
Authors: Xu Yu‐Hang , Lu Chun‐Hua , Zheng Zhong‐Hui , Shen Yue‐Mao 
Published: May 2011

AbstractFour new polyketides, botryosphaerones A–D (1–4, resp.), were obtained from the fermentation culture of Botryosphaeria australis strain ZJ12‐1A, together with four known compounds, O‐methylasparvenone (5), 6‐ethyl‐2,7‐dimethoxyjuglon (6) and its monoacetyl derivative 7, and O‐methylaspmenone (8). Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments, and HR‐Q‐TOF mass spectrometry, and by comparison with reported data. All compounds were evaluated for their cytotoxic and antimicrobial activities in vitro. Only compounds 6 and 7 showed cytotoxic and antimicrobial activities, as already reported.
Synthesis of trans‐Fused Oxabicyclo[5.2.0]nonan‐2‐ones via [2+2] Photocycloaddition of Oxepinones to Conjugated Alkenes
Authors: Schmidt Kerstin , Margaretha Paul 
Published: May 2011

AbstractOn irradiation (350 nm) in the presence of 2,3‐dimethylbuta‐1,3‐diene, benzoxepinone 2 and dioxepinone 3 were converted regio‐ and diastereoselectively to trans‐fused oxabicyclo[5.2.0]nonanones 5 and 9, respectively.
Reaction of Optically Active Oxiranes with Thiofenchone and 1‐Methylpyrrolidine‐2‐thione: Formation of 1,3‐Oxathiolanes and Thiiranes
Authors: Fu Changchun , Linden Anthony , Heimgartner Heinz 
Published: May 2011

AbstractThe SnCl4‐catalyzed reaction of (−)‐thiofenchone (=1,3,3‐trimethylbicyclo[2.2.1]heptane‐2‐thione; 10) with (R)‐2‐phenyloxirane ((R)‐11) in anhydrous CH2Cl2 at −60° led to two spirocyclic, stereoisomeric 4‐phenyl‐1,3‐oxathiolanes 12 and 13 via a regioselective ring enlargement, in accordance with previously reported reactions of oxiranes with thioketones (Scheme 3). The structure and configuration of the major isomer 12 were determined by X‐ray crystallography. On the other hand, the reaction of 1‐methylpyrrolidine‐2‐thione (14a) with (R)‐11 yielded stereoselectively (S)‐2‐phenylthiirane ((S)‐15) in 56% yield and 87–93% ee, together with 1‐methylpyrrolidin‐2‐one (14b). This transformation occurs via an SN2‐type attack of the S‐atom at C(2) of the aryl‐substituted oxirane and, therefore, with inversion of the configuration (Scheme 4). The analogous reaction of 14a with (R)‐2‐{[(triphenylmethyl)oxy]methyl}oxirane ((R)‐16b) led to the corresponding (R)‐configured thiirane (R)‐17b (Scheme 5); its structure and configuration were also determined by X‐ray crystallography. A mechanism via initial ring opening by attack at C(3) of the alkyl‐substituted oxirane, with retention of the configuration, and subsequent decomposition of the formed 1,3‐oxathiolane with inversion of the configuration is proposed (Scheme 5).
The ‘t‐Amino Effect’ of ortho‐Nitroso Amines. Synthesis of 2,6‐Diaminoadenine Derivatives from 6‐(Dialkylamino)‐5‐nitrosopyrimidines
Authors: del Carmen Ruiz Ruiz Maria , Vasella Andrea 
Published: May 2011

AbstractThe ‘t‐amino effect’ of amino‐nitroso compounds was documented by preparing the (dialkylamino)‐nitroso pyrimidines 4–18, and cyclising them under thermal conditions in high yields to the purine derivatives 19–32. The reactivity of the amino‐nitroso‐pyrimidines, particularly of 17 derived from diethyl iminodiacetate, and of 19, derived from 1‐phenylimidazolidine, correlates with the stability of the intermediate azomethine ylide. Thermolysis of the amino‐nitroso‐pyrimidines 34–37, possessing dialkylamino substituents at C(4) and C(6), proceeded by protiodenitrosation, leading to 38–41.
Organocatalyzed Michael Addition of Aldehydes to Nitro Alkenes – Generally Accepted Mechanism Revisited and Revised
Authors: Patora‐Komisarska Krystyna , Benohoud Meryem , Ishikawa Hayato , Seebach Dieter , Hayashi Yujiro 
Published: May 2011

AbstractThe amine‐catalyzed enantioselective Michael addition of aldehydes to nitro alkenes (Scheme 1) is known to be acid‐catalyzed (Fig. 1). A mechanistic investigation of this reaction, catalyzed by diphenylprolinol trimethylsilyl ether is described. Of the 13 acids tested, 4‐NO2C6H4OH turned out to be the most effective additive, with which the amount of catalyst could be reduced to 1 mol‐% (Tables 2–5). Fast formation of an amino‐nitro‐cyclobutane 12 was discovered by in situ NMR analysis of a reaction mixture. Enamines, preformed from the prolinol ether and aldehydes (benzene/molecular sieves), and nitroolefins underwent a stoichiometric reaction to give single all‐trans‐isomers of cyclobutanes (Fig. 3) in a [2+2] cycloaddition. This reaction was shown, in one case, to be acid‐catalyzed (Fig. 4) and, in another case, to be thermally reversible (Fig. 5). Treatment of benzene solutions of the isolated amino‐nitro‐cyclobutanes with H2O led to mixtures of 4‐nitro aldehydes (the products 7 of overall Michael addition) and enamines 13 derived thereof (Figs. 6–9). From the results obtained with specific examples, the following tentative, general conclusions are drawn for the mechanism of the reaction (Schemes 2 and 3): enamine and cyclobutane formation are fast, as compared to product formation; the zwitterionic primary product 5 of C,C‐bond formation is in equilibrium with the product of its collapse (the cyclobutane) and with its precursors (enamine and nitro alkene); when protonated at its nitronate anion moiety the zwitterion gives rise to an iminium ion 6, which is hydrolyzed to the desired nitro aldehyde 7 or deprotonated to an enamine 13. While the enantioselectivity of the reaction is generally very high (>97% ee), the diastereoselectivity depends upon the conditions, under which the reaction is carried out (Fig. 10 and Tables 1–5). Various acid‐catalyzed steps have been identified. The cyclobutanes 12 may be considered an off‐cycle ‘reservoir’ of catalyst, and the zwitterions 5 the ‘key players’ of the process (bottom part of Scheme 2 and Scheme 3).
Investigation of spectrally coherent resting‐state networks using non‐negative matrix factorization for functional MRI data
Authors: Lee Jong‐Hwan , Hashimoto Ryuichiro , Wible Cynthia G. , Yoo Seung‐Schik 
Published: May 2011

AbstractSpontaneous fluctuations of the functional magnetic resonance imaging (fMRI) signal during the resting state have been characterized by the dominant spectral components in the low‐frequency (<0.1 Hz) range. Although previous studies have reported the spatial patterns of activity of the resting‐state network (RSN), the frequency‐dependent characteristics (i.e., spectral coherence) of the resting state activity have not been fully investigated. This article describes the novel application of a non‐negative matrix factorization (NMF) algorithm to the decomposition of the magnitude spectra of fMRI time‐series into distinct spectral components. From the fMRI data of healthy volunteers during the resting state, the frequency‐specific components were decomposed into five basis functions. Group analysis revealed five different spatial patterns associated with these basis functions, in which each of the spatial patterns may correspond to a distinct spectrally coherent RSN. The RSN with the lowest center frequency showed a similar spatial pattern to the “default‐mode” network, which involves the medial superior and middle frontal cortex along with the posterior cingulate cortex. On the other hand, RSNs with higher frequencies were observed mainly in several posterior regions of the brain including the precuneus and lingual gyrus. Subsequent Granger causality analysis demonstrated that these posterior regions may function as the “hubs” of the RSNs, whereas the anterior regions, including the medial superior and middle frontal cortex, may be characterized as “peripheries” of the network. Our proposed analysis scheme provides supplemental information on both spectral and temporal characteristics of the RSNs, which might be used in a range of applications, including those involving clinical populations. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 2117–222, 2011
Dissimilarity‐based detection of schizophrenia
Authors: Ulaş Aydın , Duin Robert P.W. , Castellani Umberto , Loog Marco , Mirtuono Pasquale , Bicego Manuele , Murino Vittorio , Bellani Marcella , Cerruti Stefania , Tansella Michele , Brambilla Paolo 
Published: May 2011

AbstractIn this article, a novel approach to schizophrenia classification using magnetic resonance images (MRI) is proposed. The presented method is based on dissimilarity‐based classification techniques applied to morphological MRIs and diffusion‐weighted images (DWI). Instead of working with features directly, pairwise dissimilarities between expert delineated regions of interest (ROIs) are considered as representations based on which learning and classification can be performed. Experiments are carried out on a set of 59 patients and 55 controls and several pairwise dissimilarity measurements are analyzed. We demonstrate that significant improvements can be obtained when combining over different ROIs and different dissimilarity measures. We show that combining ROIs using the dissimilarity‐based representation, we achieve higher accuracies. The dissimilarity‐based representation outperforms the feature‐based representation in all cases. Best results are obtained by combining the two modalities. In summary, our contribution is threefold: (i) We introduce the usage of dissimilarity‐based classification to schizophrenia detection and show that dissimilarity‐based classification achieves better results than normal features, (ii) We use dissimilarity combination to achieve better accuracies when carefully selected ROIs and dissimilarity measures are considered, and (iii) We show that by combining multiple modalities we can achieve even better results. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 179–192, 2011
Pattern analysis in neuroimaging: Beyond two‐class categorization
Authors: Filipovych Roman , Wang Ying , Davatzikos Christos 
Published: May 2011

AbstractOne of the many advantages of multivariate pattern recognition approaches over conventional mass‐univariate group analysis using voxel‐wise statistical tests is their potential to provide highly sensitive and specific markers of diseases on an individual basis. However, a vast majority of imaging problems addressed by pattern recognition are viewed from the perspective of a two‐class classification. In this article, we provide a summary of selected works that propose solutions to biomedical problems where the widely‐accepted classification paradigm is not appropriate. These pattern recognition approaches address common challenges in many imaging studies: high heterogeneity of populations and continuous progression of diseases. We focus on diseases associated with aging and propose that clustering‐based approaches may be more suitable for disentanglement of the underlying heterogeneity, while high‐dimensional pattern regression methodology is appropriate for prediction of continuous and gradual clinical progression from magnetic resonance brain images. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 173–178, 2011
A hierarchical stimulus presentation paradigm for a P300‐based Hangul speller
Authors: Lee Tae‐Hoon , Kam Tae‐Eui , Kim Sung‐Phil 
Published: May 2011

AbstractWe propose a hierarchical stimulus presentation paradigm for a P300‐based Hangul (Korean script) input system. A P300‐based input system (or speller) is one of the most promising noninvasive brain‐computer interface (BCI) applications based on its direct applicability in many computer programs. Although the previous row/column stimulus presentation paradigm has been well‐suited to the English input, it may not be optimal for a Hangul input because Hangul has a distinct hierarchical structure. To overcome the limitation of the previous paradigms, we developed a new P300‐based Hangul input system by taking the unique hierarchical structure of Hangul into account for creating a hierarchical stimulus presentation paradigm. By using the hierarchical structure, we can effectively reduce the window size of the interface without loss of classification accuracy. A performance comparison shows that the hierarchical paradigm exhibits higher classification accuracy than the row/column paradigm even with a smaller window size. Thus, the proposed hierarchical paradigm is more efficient to spell Hangul and will be more useful for BCI‐based Hangul input for a text messenger, e‐mail program, word processor and other similar applications. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 131–138, 2011
Focused ultrasound modulates the level of cortical neurotransmitters: Potential as a new functional brain mapping technique
Authors: Min Byoung‐Kyong , Yang Po Song , Bohlke Mark , Park Shinsuk , R.Vago David , Maher Timothy J. , Yoo Seung‐Schik 
Published: May 2011

AbstractRegional modulation of the level of cortical neurotransmitters in the brain would serve as a new functional brain mapping technique to interrogate the neurochemical actions of the brain. We investigated the utility of the application of low‐intensity, pulsed sonication of focused ultrasound (FUS) to the brain to modulate the extracellular level of dopamine (DA) and serotonin (5‐HT). FUS was delivered to the thalamic areas of rats, and extracellular DA and 5‐HT were sampled from the frontal lobe using the microdialysis technique. The concentration changes of the sampled DA and 5‐HT were measured through high‐performance liquid chromatography. We observed a significant increase of the extracellular concentrations of DA and 5‐HT in the FUS‐treated group as compared with those in the unsonicated group. Our results provide the first direct evidence that FUS sonication alters the level of extracellular concentration of these monoamine neurotransmitters and has a potential modulatory effect on their local release, uptake, or degradation. Our findings suggest that the pulsed application of FUS offers new perspectives for a possible noninvasive modulation of neurotransmitters and may have diagnostic as well as therapeutic implications for DA/5‐HT‐mediated neurological and psychiatric disorders. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 232–240, 2011
Single trial variability in brain–computer interfaces based on motor imagery: Learning in the presence of labeling noise
Authors: Gouy‐Pailler Cédric , Sebag Michèle , Larue Anthony , Souloumiac Antoine 
Published: May 2011

AbstractThis article addresses the issue of learning efficient linear spatial filters and a classification function to match noninvasive electroencephalographic (EEG) signals to motor imagery tasks voluntarily performed by the subjects. The new perspective used in this article consists in releasing the widely accepted hypothesis stating that motor tasks‐related brain activities should have similar time course across trials. This work proposes a learning model that takes into account two previously unconsidered sources of variability. First, the time course of the subject's brain activity, while performing a motor imagery task, will be considered as a trial‐dependent variable. This means that the optimal time, defined as an amount of time after the trial cue, chosen to determine the task performed by the subject might be different between distinct trials. The second released hypothesis deals with the spectral discriminative brain response. Although usual learning methods do not allow any dependency between the optimal discriminative time and frequency bands, our model takes into account this possible source of variability. Therefore, the brain response in distinct frequency bands, e.g., in the mu band or beta band, could be used by the decision function at distinct instants. Based on this underlying enhanced model, we propose a two‐step procedure. In the first step, the algorithm carefully analyzes, using cross‐validation techniques, the training data to identify previously mentioned sources of variability. In the second step, the enhanced frequency‐dependent linear spatial filters and the classification function are determined. As by‐products of this analysis, substantial piece of knowledge about motor imagery is provided. First, the method allows the identification and quantification of labeling noise in brain–computer interfaces (BCIs) based on motor imagery. Second, the algorithm gives a comparative estimation of the spectral time courses during motor imagery. This article makes an extensive use of the dataset I of BCI Competition IV, which took place in 2008. It consists of a training set and a test set of 59 EEG signals recording on four subjects while performing an asynchronous BCI experiment. The two‐step procedure presented in this article is shown to significantly outperform a comparative naive approach. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 148–157, 2011
A study on combining local field potential and single unit activity for better neural decoding
Authors: Zhang Shaomin , Jiang Bo , Zhu Junming , Zhang Qiaosheng , Chen Weidong , Zheng Xiaoxiang , Zhao Ting 
Published: May 2011

AbstractRecent studies showed that the local field potential (LFP) in motor cortex carries information about parameters of limb movements and could be used as a candidate neural signal in brain‐machine interfaces to control external devices. However, it is yet to be clear how much information LFP can offer and how it can be effectively used in BMIs. In this article, we systematically evaluated the decoding performance of combining LFP and single‐unit activity (SUA) from the primary motor cortex of rats performing the lever‐pressing task. The results showed that the decoding power could be significantly improved by combining SUA and LFP in the time‐frequency mode, which is based on the separation of LFP into multiple frequency bands. Furthermore, we found that using all frequency bands might be the best choice because it yielded better or no significantly worse results than using low or high frequency bands only. This implies that different frequency components of LFP carry different information. Moreover, we demonstrated that the combination could stabilize the decoding performance even if SUA disappears over time. These results suggest that the different frequency components in the LFP play different roles in kinematics decoding and the combination of LFPs and SUA could be a promising strategy for improving neural decoding in brain‐machine interfaces.© 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 165–172, 2011
Decoding of multichannel EEG activity from the visual cortex in response to pseudorandom binary sequences of visual stimuli
Authors: Nezamfar Hooman , Orhan Umut , Purwar Shalini , Hild Kenneth , Oken Barry , Erdogmus Deniz 
Published: May 2011

AbstractElectroencephalography (EEG) signals have been an attractive choice to build noninvasive brain computer interfaces (BCIs) for nearly three decades. Depending on the stimuli, there are different responses which one could get from EEG signals. One of them is the P300 response which is a visually evoked response that has been widely studied. Steady state visually evoked potential (SSVEP) is the response to an oscillating stimulus with fixed frequency, which is detectable from the visual cortex. However, there exists some work on using an m‐sequence with different lags as the control sequence of the flickering stimuli. In this study, we used several m‐sequences instead of one with the intent of increasing the number of possible command options in a BCI setting. We also tested two different classifiers to decide between the m‐sequences and study the performance of multi channel classifiers versus single channel classifiers. The study is done over two different flickering frequencies, 15 and 30 Hz to investigate the effect of flickering frequency on the accuracy of the classification methods. Our study shows that the EEG channels are correlated, and although all the channels contain some useful information, but combining them with a multi channel classifier based on the assumption of having conditional independence will not improve the classification accuracy. In addition, we were able to get reasonably good results using the 30 Hz flickering frequency comparing with 15 Hz flickering frequency that will give us the ability of having a shorter training and decision making time. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 139–147, 2011
ENSURING SUPPLY CHAIN RESILIENCE: DEVELOPMENT OF A CONCEPTUAL FRAMEWORK
Authors: Pettit Timothy J. , Fiksel Joseph , Croxton Keely L. 
Published: May 2011

The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Air Force, the Department of Defense, or the U.S. Government.In a world of turbulent change, resilience is a key competency since even the most carefully designed supply chain is susceptible to unforeseen events. This article presents a new Supply Chain Resilience Framework to help businesses deal with change. The conceptual framework is based on extant literature and refined through a focus group methodology. Our findings suggest that supply chain resilience can be assessed in terms of two dimensions: vulnerabilities and capabilities. The Zone of Resilience is defined as the desired balance between vulnerabilities and capabilities, where it is proposed that firms will be the most profitable in the long term. We identified seven vulnerability factors composed of 40 specific attributes and 14 capability factors from 71 attributes that facilitate the measurement of resilience. The article concludes with managerial implications and recommendations for future research.
Vibrational properties of levulinic acid and furan derivatives: Raman spectroscopy and theoretical calculations
Authors: Kim Taejin , Assary Rajeev S. , Curtiss Larry A. , Marshall Christopher L. , Stair Peter C. 
Published: May 2011

AbstractIn this work, the Raman spectra of furan, furfuryl alcohol (FA), furfural, hydroxymethylfurfural (HMF), and levulinic acid were obtained in the 500 to 4000 cm−1 spectral region at room temperature. Vibrational wavenumbers were calculated for these compounds with the B3LYP method using the 6‐31 + G(2df,p) basis set. The experimentally determined CC and CC wavenumbers for furan and furan derivatives were in good agreement with the calculated wavenumbers without scaling factor, while the calculated CO and CH wavenumbers at ∼1660 and 3000 cm−1, respectively, showed larger deviations from the measured ones. The Raman spectra for furan and furan derivatives showed intense CC bands, whereas the levulinic acid spectrum showed intense CH vibrations with broad doublet CO bands. We also found that an empirical method based on the chemical structure similarities is able to predict the HMF Raman spectrum from the combined furfural and FA spectra. Copyright © 2011 John Wiley & Sons, Ltd.
Prognostic molecular biomarkers for cutaneous malignant melanoma
Authors: Tanaka Ryo , Koyanagi Kazuo , Narita Norihiko , Kuo Christine , Hoon Dave S.B. 
Published: May 2011

AbstractMolecular signatures of melanoma have propelled new approaches to early diagnosis, monitoring of treatment response, and targeted therapy. This review discusses messenger RNA (mRNA), genomic, and epigenomic melanoma biomarkers in blood and tissue specimens. The major focus is on tissue‐based molecular assays to upstage sentinel lymph nodes (SLNs), and blood‐based assays to detect melanoma progression by monitoring levels of circulating tumor cells (CTC) and circulating DNA. J. Surg. Oncol. 2011; 104:438–446. © 2011 Wiley‐Liss, Inc.