bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, Structure and Hypoxic Cytotoxicity of 3‐Amino‐1,2,4‐benzotriazine‐1,4‐dioxide Derivatives
Authors: Jiang Faqin , Weng Qinjie , Sheng Rong , Xia Qing , He Qiaojun , Yang Bo , Hu Yongzhou 
Published: April 2007

AbstractA series of novel 3‐amino‐1,2,4‐benzotriazine‐1,4‐dioxide derivatives were synthesized and screened for their in vitro cytotoxicity against promyelocytic leukemia HL‐60, androgen‐independent prostate tumor PC3, hepatocellular carcinoma Bel‐7402, human esophagus tumor ECA‐109, and human breast tumor MCF‐7 cell lines in hypoxia and in normoxia. Most compounds showed higher cytotoxic activity both in hypoxia and in normoxia. Among them, compounds 61 and 62 showed more potent cytotoxic activity and hypoxic selectivity when compared to tirapazamine.
A measure theoretic approach to information retrieval
Authors: Dominich Sándor , Kiezer Tamás 
Published: April 2007

AbstractThe vector space model of information retrieval is one of the classical and widely applied retrieval models. Paradoxically, it has been characterized by a discrepancy between its formal framework and implementable form. The underlying concepts of the vector space model are mathematical terms: linear space, vector, and inner product. However, in the vector space model, the mathematical meaning of these concepts is not preserved. They are used as mere computational constructs or metaphors. Thus, the vector space model actually does not follow formally from the mathematical concepts on which it has been claimed to rest. This problem has been recognized for more than two decades, but no proper solution has emerged so far. The present article proposes a solution to this problem. First, the concept of retrieval is defined based on the mathematical measure theory. Then, retrieval is particularized using fuzzy set theory. As a result, the retrieval function is conceived as the cardinality of the intersection of two fuzzy sets. This view makes it possible to build a connection to linear spaces. It is shown that the classical and the generalized vector space models, as well as the latent semantic indexing model, gain a correct formal background with which they are consistent. At the same time it becomes clear that the inner product is not a necessary ingredient of the vector space model, and hence of Information Retrieval (IR). The Principle of Object Invariance is introduced to handle this situation. Moreover, this view makes it possible to consistently formulate new retrieval methods: in linear space with general basis, entropy‐based, and probability‐based. It is also shown that Information Retrieval may be viewed as integral calculus, and thus it gains a very compact and elegant mathematical way of writing. Also, Information Retrieval may thus be conceived as an application of mathematical measure theory.
Metal‐Ion‐Mediated Tuning of Duplex DNA Binding by Bis(2‐(2‐pyridyl)‐1H‐benzimidazole)
Authors: Bhattacharya Santanu , Chaudhuri Padmaparna 
Published: April 2007

AbstractStudies of double‐stranded‐DNA binding have been performed with three isomeric bis(2‐(n‐pyridyl)‐1H‐benzimidazole)s (n=2, 3, 4). Like the well‐known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg2+, Co2+, Ni2+, Cu2+, and Zn2+. Ligand–DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2‐pyridyl derivative to DNA is dramatically reduced in the presence of Co2+, Ni2+, and Cu2+ ions and is abolished completely at a ligand/metal‐cation ratio of 1:1. Control experiments done with the isomeric 3‐ and 4‐pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition‐metal ions. The ability of 2‐(2‐pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely.
Bayesian State Space Models for Inferring and Predicting Temporal Gene Expression Profiles
Authors: Liang Yulan , Kelemen Arpad 
Published: April 2007

AbstractPrediction of gene dynamic behavior is a challenging and important problem in genomic research while estimating the temporal correlations and non‐stationarity are the keys in this process. Unfortunately, most existing techniques used for the inclusion of the temporal correlations treat the time course as evenly distributed time intervals and use stationary models with time‐invariant settings. This is an assumption that is often violated in microarray time course data since the time course expression data are at unequal time points, where the difference in sampling times varies from minutes to days. Furthermore, the unevenly spaced short time courses with sudden changes make the prediction of genetic dynamics difficult. In this paper, we develop two types of Bayesian state space models to tackle this challenge for inferring and predicting the gene expression profiles associated with diseases. In the univariate time‐varying Bayesian state space models we treat both the stochastic transition matrix and the observation matrix time‐variant with linear setting and point out that this can easily be extended to nonlinear setting. In the multivariate Bayesian state space model we include temporal correlation structures in the covariance matrix estimations. In both models, the unevenly spaced short time courses with unseen time points are treated as hidden state variables. Bayesian approaches with various prior and hyper‐prior models with MCMC algorithms are used to estimate the model parameters and hidden variables. We apply our models to multiple tissue polygenetic affymetrix data sets. Results show that the predictions of the genomic dynamic behavior can be well captured by the proposed models. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aromaticity in Metallabenzenes
Authors: Fernández Israel , Frenking Gernot 
Published: April 2007

AbstractThe electronic structure and bonding situation in 21 metallabenzenes (metal=Os, Ru, Ir, Rh, Pt, and Pd) were investigated at the DFT level (BP86/TZ2P) by using an energy decomposition analysis (EDA) of the interaction energy between various fragments. The aim of the work is to estimate the strength of the π bonding and the aromatic character of the metallacyclic compounds. Analysis of the electronic structure shows that the metallacyclic moiety has five occupied π orbitals, two with b1 symmetry and three with a2 symmetry, which describe the π‐bonding interactions. The metallabenzenes are thus 10 π‐electron systems. This holds for 16‐electron and for 18‐electron complexes. The π bonding in the metallabenzenes results mainly from the b1 contribution, but the a2 contribution is not negligible. Comparison of the π‐bonding strength in the metallacyclic compounds with acylic reference molecules indicates that metallabenzenes should be considered as aromatic compounds whose extra stabilization due to aromatic conjugation is weaker than in benzene. The calculated aromatic stabilization energies (ASEs) are between 8.7 kcal mol−1 for 13 and 37.6 kcal mol−1 for 16 which is nearly as aromatic as benzene (ASE=42.5 kcal mol−1). The classical metallabenzene model compounds 1 and 4 exhibit intermediate aromaticity with ASE values of 33.4 and 17.6 kcal mol−1. The greater stability of the 5d complexes compared with the 4d species appears not to be related to the strength of π conjugation. From the data reported here there is no apparent trend or pattern which indicates a correlation between aromatic stabilization and particular ligands, metals, coordination numbers or charge. The lower metal–C5H5 binding energy of the 4d complexes correlates rather with weaker σ‐orbital interactions.
Generation, Characterization, and Electrochemical Behavior of the Palladium–Hydride Cluster [Pd3(dppm)3(μ3‐CO)(μ3‐H)]+ (dppm=Bis(diphenylphosphinomethane)
Authors: Cugnet Cyril , Lucas Dominique , Collange Edmond , Hanquet Bernard , Vallat Alain , Mugnier Yves , Soldera Armand , Harvey Pierre D. 
Published: April 2007

AbstractAddition of formate on the dicationic cluster [Pd3(dppm)3(μ3‐CO)]2+ (dppm=bis(diphenylphosphinomethane) affords quantitatively the hydride cluster [Pd3(dppm)3(μ3‐CO)(μ3‐H)]+. This new palladium–hydride cluster has been characterised by 1H NMR, 31P NMR and UV/Vis spectroscopy and MALDI‐TOF mass spectrometry. The unambiguous identification of the capping hydride was made from 2H NMR spectroscopy by using DCO2− as starting material. The mechanism of the hydride complex formation was investigated by UV/Vis stopped‐flow methods. The kinetic data are consistent with a two‐step process involving: 1) host–guest interactions between HCO2− and [Pd3(dppm)3(μ3‐CO)]2+ and 2) a reductive elimination of CO2. Two alternatives routes to the hydride complex were also examined : 1) hydride transfer from NaBH4 to [Pd3(dppm)3(μ3‐CO)]2+ and 2) electrochemical reduction of [Pd3(dppm)3(μ3‐CO)]2+ to [Pd3(dppm)3(μ3‐CO)]0 followed by an addition of one equivalent of H+. Based on cyclic voltammetry, evidence for a dual mechanism (ECE and EEC; E=electrochemical (one‐electron transfer), C=chemical (hydride dissociation)) for the two‐electron reduction of [Pd3(dppm)3(μ3‐CO)(μ3‐H)]+ to [Pd3(dppm)3(μ3‐CO)]0 is provided, corroborated by digital simulation of the experimental results. Geometry optimisations of the [Pd3(H2PCH2PH2)3(μ3‐CO)(μ3‐H)]n model clusters were performed by using DFT at the B3 LYP level. Upon one‐electron reductions, the PdPd distance increases from a formal single bond (n=+1), to partially bonding (n=0), to weak metal–metal interactions (n=−1), while the PdH bond length remains relatively the same.
Noncovalent Interactions and Internal Dynamics in Dimethoxymethane–Water
Authors: Favero Laura B. , Giuliano Barbara M. , Melandri Sonia , Maris Assimo , Caminati Walther 
Published: April 2007

AbstractThe millimeter‐wave absorption and Fourier transform microwave spectra of five isotopologues of the 1:1 adduct of dimethoxymethane–water have been measured in supersonic expansions. Each rotational transition appears as a quintuplet, due to the internal rotation of the two methyl groups, which are nonequivalent in the adduct. The water moiety, linked asymmetrically to dimethoxymethane, behaves as a proton donor to one of its oxygen atoms and interferes with the internal rotation of the farther methyl group through a CH⋅⋅⋅O interaction. From the analysis of the observed splittings, the V3 barriers to the internal rotation of the two methyl groups have been determined to be 6.83(8) and 6.19(8) kJ mol−1. The hydrogen bond structural parameters have been determined, the OH⋅⋅⋅O and CH⋅⋅⋅O distances being 1.93(1) and 2.78(4) Å, respectively.
Assessment of ifosfamide pharmacokinetics, toxicity, and relation to CYP3A4 activity as measured by the erythromycin breath test in patients with sarcoma
Authors: Chugh Rashmi , Wagner Thomas , Griffith Kent A. , Taylor Jeremy M.G. , Thomas Dafydd G. , Worden Francis P. , Leu Kirsten M. , Zalupski Mark M. , Baker Laurence H. 
Published: April 2007

AbstractBACKGROUND.Ifosfamide is a chemotherapeutic agent that requires cytochrome P450 3A (CYP3A) for bioactivation and metabolism. To the authors' knowledge, the correlation between dose, pharmacokinetics, CYP3A, and toxicity has not been fully evaluated. A randomized Phase II trial was performed on 22 soft tissue sarcoma patients treated with doxorubicin (60 mg/m2/cycle) and either high‐dose ifosfamide (12 g/m2/cycle) or standard‐dose ifosfamide (6 g/m2/cycle). The pharmacokinetics of ifosfamide and CYP3A measurements observed are reported.METHODS.Pharmacokinetic parameters for ifosfamide, 2‐dichloroethylifosfamide (2‐DCE), and 3‐dichloroethylifosfamide (3‐DCE) were collected after the first ifosfamide infusion in 13 patients. Bayesian designed limited pharmacokinetic data were collected from an additional 41 patients. The erythromycin breath test (ERMBT) was performed on 81 patients as an in vivo phenotypic assessment of CYP3A activity.RESULTS.Fourteen‐hour (peak) plasma levels of ifosfamide, 2‐DCE, and 3‐DCE were found to correlate strongly with the respective area under the curve (AUC) 0–24 values (r= 0.97, 0.94, and 0.95;P< .0001). Patients who experienced a grade 3–4 absolute neutrophil count (ANC), platelet, or creatinine toxicity (using the National Cancer Institute Common Toxicity Criteria [version 2]) were found to have statistically significantly higher median 14‐hour plasma levels of ifosfamide, 2‐DCE, and 3‐DCE compared with patients with grade 0–2 toxicity. ERMBT was not found to correlate with pharmacokinetic parameters of ifosfamide and metabolites or toxicity.CONCLUSIONS.The 14‐hour plasma level of ifosfamide, 2‐DCE, and 3‐DCE is a simple and appropriate substitute for describing the AUC of ifosfamide after 1 day of a 1‒hour to 2‐hour infusion of drug. Fourteen‐hour plasma levels of ifosfamide and metabolites are useful predictors of neutropenia, thrombocytopenia, and creatinine toxicity. ERMBT was not found to accurately correlate with ifosfamide pharmacokinetics or clinical toxicity. Cancer 2007. © 2007 American Cancer Society.
Method of determination of the reticulocyte age distribution from flow cytometry count by a structured‐population model
Authors: Wiczling Paweł , Krzyzanski Wojciech 
Published: April 2007

AbstractBackground:A flow cytometry count of reticulocytes (RET) provides information about distribution of signal emitted by reticulocyte RNA. A new method of determination of the RNA degradation rate in RET is provided. This technique allows one to determinate the age distribution of RET.Methods:The method is based on a series of flow cytometry counts of cultured RET. From those counts, the changes of signal distribution of RET over time are obtained. The RNA degradation rate of individual RET is then resolved based on changes in the signal distribution of the whole population of cells. The obtained relation between signal and age allows obtaining a RET age density that can be used to characterize RET age distribution and age dependence of processes that control the population dynamics.Results:The total maturation time of RET in rats is 3 days. The median time that a homeostatic RET spends in blood or before it becomes a mature RBC is about 0.6 days, whereas a stress RET needs 0.8 days.Conclusions:The proposed method provides means for studies in vivo RET dynamics using age‐structured models. © 2007 International Society for Analytical Cytology
Efficient selection of silenced primary cells by flow cytometry
Authors: Martínez‐Ferrandis José I. , Soriano Miguel A. , Martínez‐Romero Alicia , Herrera Guadalupe , Cervantes Andrés , O'Connor José‐E. , Knecht Erwin , Armengod M.‐Eugenia 
Published: April 2007

AbstractBackground:RNA interference has emerged as a new and potent tool to knockdown the expression of target genes and to investigate their functions. For short time experiments with mammalian cell lines, RNA interference is typically induced by transfecting small interfering RNAs (siRNAs). Primary cells constitute important experimental systems in many studies because of their similarity to their in vivo counterparts; however, transfection of these cells has been found to be difficult. As a consequence, RNA interference of primary cells may result in mixed phenotypes because of the simultaneous presence in the same preparation of transfected and nontransfected cells. This may be particularly inconvenient when certain experiments (for example, biochemical analysis) should be performed.Methods:We use fluorescently labeled siRNAs to induce RNA interference in fibroblasts, and flow‐cytometry associated cell sorting to separate subpopulations of transfected cells according to fluorescence intensity.Results:Flow cytometry allows one to discriminate between strongly‐ and weakly‐ or nonsilenced fibroblasts, since the fluorescence intensity of transfected cells is related to the number of internalized siRNA copies and to the mRNA knockdown efficiency.Conclusions:The use of fluorescently labeled siRNAs may allow one to isolate by flow‐cytometry associated cell sorting the most efficiently silenced primary cells for subsequent analysis. © 2007 International Society for Analytical Cytology
Does muscular weakness account for younger children's enhanced force variability?
Authors: Sosnoff Jacob J. , Deutsch Katherine M. , Newell Karl M. 
Published: April 2007

AbstractThis study examined the degree to which younger children's greater variability in force control is associated with muscular weakness. Children aged 6, 8, and 10 years and adults aged 18–22 years produced isometric force via index finger metacaro‐phalangeal joint flexion to varying force levels (5%, 15%, 25%, and 35% maximal voluntary contraction). The force output of the younger children was more variable and had greater time dependent structure compared to that of the adults at all force levels. However, the effect of age on variability was significantly reduced, but not eliminated when absolute muscular strength was taken into account. It is concluded that age‐related changes in children's force control result from a multitude of developmental processes including increases in muscular strength. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 399–405, 2007.
Fine‐tuning of social play in juvenile lowland gorillas (gorilla gorilla gorilla)
Authors: Palagi Elisabetta , Antonacci Daniela , Cordoni Giada 
Published: April 2007

AbstractSocial play, which involves cooperation, communication, and learning, may represent a suitable field for the investigation of cognitive ability in a given species. We collected data on a captive group of gorillas in order to evaluate the potential cognitive skill of juveniles in fine‐tuning play behavior. This study revealed that juvenile gorillas are able to “place” the play session in a proper spatial/temporal context, thus evaluating a complex net of factors (e.g., play partner, play roughness, group activity, space availability). When animals play fight, they use patterns of agonistic functional contexts. Since these actions are not intrinsically different from their “serious” context, it may be hard to distinguish them. One of the most important function of play in the ontogeny of primate social cognition may be to recognize stimuli, which may indicate the intentions of conspecifics. Accordingly, we found that juvenile gorillas are able to use play signals appropriately when a clear statement of purpose is necessary (i.e., during male–male competitive play sessions and when the escape opportunities are limited). The ability to interpret such ambiguous features of social signaling could represent a central issue in the evolution of behavioral flexibility and intelligence in primates. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 433–445, 2007.
Utilizing nonlinear behavior of microbubbles in medical ultrasound
Authors: Umemura Shin‐Ichiro , Kawabata Ken‐Ichi , Sasaki Kazuaki 
Published: April 2007

AbstractMicrobubbles exposed to ultrasound exhibit extremely nonlinear conspicuous behaviors. Medical imaging makes wide use of the pulse inversion method, in which only this nonlinear component is extracted by adding the received signals obtained by sending the phase inverted ultrasonic pulses twice. Further, there have been research efforts to use this nonlinear behavior for sonochemical healing of tumors by the efficient generation of acoustic cavitation by illumination with the second harmonic superimposed on the fundamental wave. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 63–69, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20259
The construction of periodically time‐variant convolutional codes using binary linear block codes
Authors: Ogasahara Naonori , Kobayashi Manabu , Hirasawa Shigeichi 
Published: April 2007

AbstractIn 1996 Rosenthal and York proposed (time‐invariant) BCH convolutional codes [4] in which the parity check matrix of a BCH code is used in the construction of the convolutional code. The lower bound on the minimum free distance of a BCH convolutional code is guaranteed by the BCH limit. In this paper we propose a periodically time‐variant convolutional code that can be constructed not only using the BCH parity check matrix but using the check matrix of any binary linear block code and show that the lower bound on the minimum free distance is guaranteed by the minimum free distance of the binary linear block code. In addition, taking 12 binary linear block codes as examples, we perform comparisons of the proposed codes with BCH convolutional codes using three evaluation criteria (minimum free distance, number of delay elements, coding rate) and show that there exist proposed codes that are superior to existing ones. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 31– 40, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20271
Neuro‐hardware for peak power reduction of oversampled OFDM signal
Authors: Mori Atsushi , Ohta Masaya , Yamashita Katsumi 
Published: April 2007

AbstractOFDM communication system has recently been attracting attention because of its features of high spectrum efficiency and robustness in a multipath environment. The OFDM signal often exhibits a high peak power. It is important to reduce the peak power, since communication quality is degraded and unnecessary outband power radiation is produced when such a signal is amplified by a nonlinear amplifier. This paper considers the peak power suppression problem in an oversampled OFDM signal and presents a solution using a mutually coupled neural network. The peak power suppression performance of the proposed method and the accompanying reduction of the outband radiation power and the bit error rate are evaluated by numerical experiments. Neuro‐hardware which can handle the peak power suppression process in real time is experimentally constructed, and its performance is evaluated. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 54– 62, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20285
Fast aperiodic correlation algorithm for real‐valued shift‐orthogonal finite‐length sequence of length 2ν+1
Authors: Tanada Yoshihiro , Matsumoto Takahiro 
Published: April 2007

AbstractReal‐valued shift‐orthogonal finite‐length sequences are sequences in which the side lobes of the aperiodic autocorrelation function become 0, except for the endpoints of the shift to both sides, and can be applied in pulse compression radar and spread spectrum communications. In this paper, a fast correlation algorithm for efficiently calculating the periodic correlation function is discussed for real‐valued shift‐orthogonal finite‐length sequences with lengthM=2ν+1. For input data, including a real‐valued shift‐orthogonal finite‐length sequence over a certain range, the value of the aperiodic correlation function is found in a certain shift range. Based on the synthesis of this sequence by the convolution of ν+1 partial sequences, the correlation processing is broken down into correlation processing of the ν+1 stages of partial sequences. As a result, the number of multiplications and the number of additions can be suppressed on the orderMlog2M. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 18– 30, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20301