bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new framework for characterising the number of handovers in cellular networks
Authors: Bziuk Wolfgang , Zaghloul Said , Jukan Admela 
Published: September 2009

AbstractThe handover process was widely studied in the literature in the past decade. While significant efforts addressed the mean handover rate, few attempted to characterise the distribution of the number of handovers under the assumption that the call and the cell residence times (CRTs) are generally distributed. Motivated by the increasing impact of handovers on the design and performance of the control and data planes in the emerging cellular networks, in this paper, we propose a new analytical framework to obtain the probability generating function (PGF) of the number of handovers. Our work covers three generic session behaviours, including new, roaming and location triggered calls, and thus facilitates the calculation of the mean number of handovers for such session types. When the distributions have rational Laplace transforms, we obtain closed form solutions that are simple‐to‐compute and hence provide cellular network designers and researchers with deeper insights into the performance of mobility aware wireless protocols for different application scenarios. Our results show that handover models for new sessions can reasonably approximate location triggered sessions while separate treatment for roaming sessions is generally required. The numerical examples based on the generic hyper‐Erlang session durations show the practicability of our framework. Copyright © 2009 John Wiley & Sons, Ltd.
Laminar separation bubble on an Eppler 61 airfoil
Authors: Savaliya Samir B. , Kumar S. Praveen , Mittal Sanjay 
Published: September 2009

AbstractLaminar separation bubble that occurs on the suction side of the Eppler 61 airfoil at Re=46000 is studied. The incompressible flow equations are solved using a stabilized finite element method. No turbulence model is used. The variation of the bubble length and its location, with the angle of attack (α), is studied in detail. An abrupt increase in the lift coefficient is observed at α∼4.5°. It is found to be related to a sudden decrease in the separation bubble length at the trailing edge of the airfoil. Significant differences are observed in the results from the 2D and 3D computations. Stall is observed in 3D simulations, but is found to be absent in 2D. The laminar bubble, which fails to reattach in 3D for α>14°, continues to reattach for α as large as 20° in the 2D computations. Reynolds stress calculations in both 2D and 3D indicate the extent to which the outer flow is affected by the presence of bubble. It is found that the Reynolds stress components \documentclass{article}\footskip=0pc\pagestyle{empty}\begin{document}${\over{u{^\prime}}{v{^\prime}}}$\end{document} and \documentclass{article}\footskip=0pc\pagestyle{empty}\begin{document}${\over{u{^\prime}}{w{^\prime}}}$\end{document} are of comparable order of magnitude indicating that spanwise fluctuations are significant. The effect of the time window used to compute the time‐averaged aerodynamic coefficients is studied. The time‐averaged and root mean square (rms) value of the aerodynamic coefficients are calculated for both 2D and 3D computations and compared with the previously published experimental results. The 3D computations show good agreement with the earlier data. The variation of the rms value of the aerodynamic coefficients with angle of attack shows certain peaks. The cause of their appearance is investigated. The effect of Reynolds number is studied. The increase in Re at α=10° is found to reduce the bubble length and cause it to move closer to the leading edge. Copyright © 2009 John Wiley & Sons, Ltd.
Improvement of the WENO scheme smoothness estimator
Authors: Shen Yiqing , Zha Gecheng 
Published: September 2009

AbstractThis paper has analyzed the weights of the fifth‐order weighted essentially nonoscillatory scheme suggested by Jiang and Shu and a modified smoothness estimator is suggested to improve the accuracy. Using a function of the minimum and maximum of the original smoothness estimators, the new smoothness estimators have smaller variation among them than the original ones in smooth regions. Hence, as the new weights are closer to the optimal weights, the numerical accuracy is improved. Several numerical experiments are presented to demonstrate the accuracy and robustness of the new scheme. Copyright © 2009 John Wiley & Sons, Ltd.
Influence of Barium Incorporation on the Electrochemical Performance of Ln0.58Sr0.4Fe0.8Co0.2O3–δ(Ln=La, Pr, Sm) Perovskites for Oxygen Activation at Intermediate Temperatures
Authors: Vert V. B. , Serra J. M. 
Published: September 2009

AbstractHighly active perovskite‐based electrodes were obtained through partial substitution of lanthanides (La, Pr and Sm) by barium in the Ln0.58Sr0.4Fe0.8Co0.2O3system. These compositions were obtained as single phase crystalline compounds through a sol–gel synthetic route and tested by electrochemical impedance spectroscopy (EIS) as symmetrical cells on GDC‐electrolyte samples in the temperature range 450–650 °C. Cooperative effects arose through the incorporation of a large divalent active cation (Ba+2) in the perovskite lattice of lanthanide‐based strontium ferrites‐cobaltites. Reduction in the electrode polarisation resistance with respect to non‐substituted compositions is obtained irrespective of the amount of barium substitution and lanthanide nature. Barium addition also reduces the activation energy of these compositions, indicating changes in the oxygen activation processes. The specific effect of the barium incorporation on the electrode performance was dependent on the nature of the partially substituted lanthanide. Lanthanum–barium‐based compositions exhibited the lowest electrode polarisation resistance when the amount of the replaced barium was increased up to 50% molar. On the other hand, for praseodymium‐ or samarium–barium‐based compositions, the minimum in electrode polarisation resistance was achieved at barium substitutions close to 25% molar. The study of the effect of oxygen partial pressure on EIS data allowed in improving the understanding of the processes governing the electrode operation.
Maturation of the hippocampal formation and amygdala in Macaca mulatta: A volumetric magnetic resonance imaging study
Authors: Payne Christa , Machado Christopher J. , Bliwise Nancy G. , Bachevalier Jocelyne 
Published: September 2009

AbstractMalformations of the hippocampal formation and amygdala have been implicated in several neurodevelopmental disorders; yet relatively little is known about their normal structural development. The purpose of this study was to characterize the early developmental trajectories of the hippocampus and amygdala in the rhesus macaques (Macaca mulatta) using noninvasive MRI techniques. T1‐weighted structural scans of 22 infant and juvenile monkeys (11 male, 11 female) were obtained between 1 week and approximately 2 yrs of age. Ten animals (five males, five females) were scanned multiple times and 12 monkeys (six males, six females) were scanned once between 1 and 4 weeks of age. Both structures exhibited significant age‐related changes throughout the first 2 yrs of life that were not explained by overall brain development. The hippocampal formation increased 117.05% in males and 110.86% in females. No sex differences were evident, but the left hemisphere was significantly larger than the right. The amygdala increased 86.49% in males and 72.94% in females with males exhibiting a larger right than left amygdala. For both structures, the most substantial volumetric increases were seen within the first month, but the hippocampal formation appeared to develop more slowly than the amygdala with the rate of hippocampal maturation stabilizing around 11 months and that of amygdala maturation stabilizing around 8 months. Differences in volumetric developmental trajectories of the hippocampal formation and amygdala largely mirror differences in the timing of the functional development of these structures. The current results emphasize the importance of including early postnatal ages when assessing developmental trajectories of neuroanatomical structures and reinforces the utility of nonhuman primates in the assessment of normal developmental patterns. © 2009 Wiley‐Liss, Inc.
Distinct modes of modulation of GABAergic transmission by Group I metabotropic glutamate receptors in rat entorhinal cortex
Authors: Deng Pan‐Yue , Xiao Zhaoyang , Lei Saobo 
Published: September 2009

AbstractActivation of metabotropic glutamate receptors (mGluRs) modulates synaptic transmission, whereas the roles of mGluRs in GABAergic transmission in the entorhinal cortex (EC) are elusive. Here, we examined the effects of mGluRs on GABAergic transmission onto the principal neurons in the superficial layers of the EC. Bath application of DHPG, a selective Group I mGluR agonist, increased the frequency and amplitude of spontaneous IPSCs (sIPSCs) whereas application of DCG‐IV, an agonist for Group II mGluRs or L‐AP4, an agonist for Group III mGluRs failed to change significantly sIPSC frequency and amplitude. Bath application of DHPG failed to change significantly the frequency and amplitude of miniature IPSCs (mIPSCs) recorded in the presence of tetradotoxin but significantly reduced the amplitude of IPSCs evoked by extracellular field stimulation or in synaptically connected interneuron‐pyramidal neuron pairs in layer III of the EC. DHPG increased the frequency but reduced the amplitude of APs recorded from entorhinal interneurons. Bath application of DHPG generated membrane depolarization and increased the input resistance of GABAergic interneurons. DHPG‐mediated depolarization of GABAergic interneurons was mediated by inhibition of background K+ channels which are insensitive to extracellular Cs+, TEA, 4‐AP, and Ba2+. DHPG‐induced facilitation of sIPSCs was mediated by mGluR5 and required the function of Gαq but was independent of phospholipase C activity. Elevation of synaptic glutamate concentration by bath application of glutamate transporter inhibitors significantly increased sIPSC frequency and amplitude demonstrating a physiological role of mGluRs in GABAergic transmission. Our results provide a cellular and molecular mechanism to explain the physiological and pathological roles of mGluRs in the EC. © 2009 Wiley‐Liss, Inc.
Exchange protein activated by cyclic AMP 2 (Epac2) plays a specific and time‐limited role in memory retrieval
Authors: Ostroveanu Anghelus , van der Zee Eddy A. , Eisel Ulrich L.M. , Schmidt Martina , Nijholt Ingrid M. 
Published: September 2009

AbstractKnowledge on the molecular mechanisms involved in memory retrieval is limited due to the lack of tools to study this stage of the memory process. Here we report that exchange proteins activated by cAMP (Epac) play a surprisingly specific role in memory retrieval. Intrahippocampal injection of the Epac activator 8‐pCPT‐2′O‐Me‐cAMP was shown to improve fear memory retrieval in contextual fear conditioning whereas acquisition and consolidation were not affected. The retrieval enhancing effect of the Epac activator was even more prominent in the passive avoidance paradigm. Down‐regulation of Epac2 expression in the hippocampal CA1 area impaired fear memory retrieval when the memory test was performed 72 h after training, but not when tested after 17 days. Our data thus identify an important time‐limited role for hippocampal Epac2 signaling in cognition and opens new avenues to investigate the molecular mechanisms underlying memory retrieval. © 2009 Wiley‐Liss, Inc.
Expression of the snoRNA host gene gas5 in the hippocampus is upregulated by age and psychogenic stress and correlates with reduced novelty‐induced behavior in C57BL/6 mice
Authors: Meier Ingo , Fellini Laetitia , Jakovcevski Mira , Schachner Melitta , Morellini Fabio 
Published: September 2009

AbstractThe growth arrest specific 5 (gas5) is a noncoding protein gene that hosts small nucleolar RNAs. Based on the observation that gas5 RNA level in the brain is highest in the hippocampus and remarkably enhanced in aged mice, we tested the hypothesis that gas5 is involved in functions controlled by the hippocampus and known to be affected by age, such as spatial learning and novelty‐induced behaviors. We show that aged (22‐month‐old) C57BL/6 male mice have spatial‐learning impairments, reduced novelty‐induced exploration, and enhanced gas5 RNA levels in the hippocampus compared to young (3‐month‐old) mice. At both ages, levels of gas5 RNA in the hippocampus negatively correlated with novelty‐induced exploration in the open field and elevated‐plus maze tests. No correlations were found between gas5 RNA levels in the hippocampus and performance in the water maze test. The expression of gas5 RNA in the rest of the brain did not correlate with any behavioral parameter analyzed. Because variations in novelty‐induced behaviors could be caused by stressfull experiences, we analyzed whether gas5 RNA levels in the hippocampus are regulated by acute stressors. We found that gas5 RNA levels in the hippocampus were upregulated by 50% 24 h after a psychogenic stressor (60‐min olfactory contact with a rat) but were unchanged after exposure to an unfamiliar environment or after acquisition of new spatial information in a one‐trial learning task. The present results suggest that strong psychogenic stressors upregulate gas5 RNA in the hippocampus, which in turn affects novelty‐induced responses controlled by this region. We hypothesize that long‐life exposure to stressors causes an age‐dependent increase in hippocampal gas5 RNA levels, which could be responsible for age‐related reduced novelty‐induced behaviors, thus suggesting a new mechanism by which ageing and stress affect hippocampal function. © 2009 Wiley‐Liss, Inc.
Functional emergence of the hippocampus in context fear learning in infant rats
Authors: Raineki Charlis , Holman Parker J. , Debiec Jacek , Bugg Melissa , Beasley Allyson , Sullivan Regina M. 
Published: September 2009

AbstractThe hippocampus is a part of the limbic system and is important for the formation of associative memories, such as acquiring information about the context (e.g., the place where an experience occurred) during emotional learning (e.g., fear conditioning). Here, we assess whether the hippocampus is responsible for pups' newly emerging context learning. In all experiments, postnatal day (PN) 21 and PN24 rat pups received 10 pairings of odor‐0.5 mA shock or control unpaired odor‐shock, odor only, or shock only. Some pups were used for context, cue or odor avoidance tests, while the remaining pups were used for c‐Fos immunohistochemistry to assess hippocampal activity during acquisition. Our results show that cue and odor avoidance learning were similar at both ages, while contextual fear learning and learning‐associated hippocampal (CA1, CA3, and dentate gyrus) activity (c‐Fos) only occurred in PN24 paired pups. To assess a causal relationship between the hippocampus and context conditioning, we infused muscimol into the hippocampus, which blocked acquisition of context fear learning in the PN24 pups. Muscimol or vehicle infusions did not affect cue learning or aversion to the odor at PN21 or PN24. The results suggest that the newly emerging contextual learning exhibited by PN24 pups is supported by the hippocampus. © 2009 Wiley‐Liss, Inc.
Two New Kaempferol Glycosides from Androsace umbellata
Authors: Lei Jun , Xiao Yun‐Chuan , Huang Jing , Tang Min , Deng Peng‐Chi 
Published: September 2009

AbstractTwo new kaempferol glycosides, 5‐hydroxy‐2‐(4‐hydroxyphenyl)‐4‐oxo‐7‐(α‐L‐rhamnopyranosyloxy)‐4H‐chromen‐3‐yl 2‐O‐acetyl‐3‐O‐β‐D‐glucopyranosyl‐α‐L‐rhamnopyranoside (1) and 5‐hydroxy‐2‐(4‐hydroxyphenyl)‐4‐oxo‐7‐(α‐L‐rhamnopyranosyloxy)‐4H‐chromen‐3‐yl β‐D‐glucopyranosyl‐(1→2)‐6‐O‐[(2E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoyl]‐β‐D‐glucopyranosyl‐(1→2)‐β‐D‐glucopyranoside (2), along with ten known compounds, were isolated from the 95% EtOH extract of the whole plant of Androsace umbellata. The structures of the new glycosides were determined on the basis of detailed spectroscopic analyses, including 1D‐ and 2D‐NMR, MS, and chemical methods.
Unexpected Ring Expansion of the (3aS,6aR)‐γ‐Thiolactone Moiety during the Introduction of the (+)‐Biotin Side Chain
Authors: Huang Jian , Xiong Fei , Wang Zhong‐Hua , Chen Fen‐Er 
Published: September 2009

AbstractThe reaction of vinylmagnesium bromide with the (3aS,6aR)‐γ‐thiolactone 2 in THF afforded, after unexpected ring expansion of the γ‐thiolactone moiety, the seven‐membered‐ring ketone 5 in excellent yield, instead of the expected tertiary alcohol 3.
Sesquiterpenes from the Marine Red Alga Laurencia saitoi
Authors: Su Hua , Yuan Zhao‐Hui , Li Jing , Guo Shu‐Ju , Deng Li‐Ping , Han Li‐Jun , Zhu Xiao‐Bin , Shi Da‐Yong 
Published: September 2009

AbstractTogether with five known sesquiterpenes, EtOH extraction of Laurencia saitoi yielded four new compounds, including three sesquiterpenes and one norsesquiterpene derivative. Their structures and relative configurations were elucidated by spectroscopic methods, including 1D‐ and 2D‐NMR (1H,1H‐COSY, HMQC, HMBC, and NOESY), as well as low‐ and high‐resolution mass‐spectrometric analyses.
Five New Triterpenoids from the Roots of Kadsura coccinea
Authors: Wang Nan , Li Zhan‐Lin , Li Dan‐Yi , Pei Yue‐Hu , Hua Hui‐Ming 
Published: September 2009

AbstractA phytochemical investigation of an EtOH extract of the roots of Kadsura coccinea (Lem.) A. C. Sm. furnished five new lanostane‐type triterpenoids, coccinone A (1), coccinone B (2), coccinone C (3), coccinone D (4), and coccinilactone B (5). Their structures were determined based on spectroscopic analyses, including 2D‐NMR experiments and HR‐MS techniques.
Three New ent‐Labdane Diterpenoids from the Wood of Excoecaria agallochaLinn.
Authors: Gowri Ponnapalli Mangala , Bhattar Sri Vedavyasa Srirangaraja Radhakrishnan , Reddy Poreddy Guruva , Rakesh Yerraballi , Basha Shaik Jeelani , Sarma Akella Venkata Subrahmanya , Rao Janaswamy Madhusudana 
Published: September 2009

AbstractAn extensive study of metabolites present in Excoecaria agallocha Linn. led to the isolation of three new ent‐labdane‐type diterpenoids, named agallochaexcoerins A–C (1–3), besides three known compounds. The skeleton present in compound 1 is rather unusual, containing of a seven‐membered lactone. The structures were elucidated on the basis of spectroscopic studies and comparison with known related compounds. The isolated compounds 1–6 were not active against Raw 264.7 (macrophage‐like), K 562 (leukemia), and COLO 205 (colon) human carcinoma cell lines.
Four New Eudesmane Sesquiterpenoid Lactones from Chloranthus serratus
Authors: Teng Fei , Zhong Hui‐Min , Chen Chang‐Xiang , Liu Hai‐Yang 
Published: September 2009

AbstractFour new eudesmane sesquiterpenoids endowed with an α,β‐unsaturated γ‐lactone five‐membered ring, serralactones A–D (1–4, resp.), along with seven known sesquiterpenoids, were isolated from the whole plant Chloranthus serratus. Their structures and relative configurations were established on the basis of extensive spectroscopic analyses.
Nitrogen‐Rich Compounds of the Lanthanoids: The 5,5′‐Azobis[1H‐tetrazol‐1‐ides] of some Yttric Earths (Tb, Dy, Ho, Er, Tm, Yb, and Lu)
Authors: Steinhauser Georg , Giester Gerald , Wagner Christoph , Leopold Nicolae , Sterba Johannes H. , Lendl Bernhard , Bichler Max 
Published: September 2009

AbstractA set of N‐rich salts, 3–9, of the heavy lanthanoids (terbium, 3; dysprosium, 4; holmium 5; erbium, 6; thulium, 7; ytterbium, 8; lutetium, 9) based on the energetic 5,5′‐azobis[1H‐tetrazole] (H2ZT) was synthesized and characterized by elemental analysis, vibrational (IR and Raman) spectroscopy, and X‐ray structure determination. The synthesis of the lanthanoid salts 3–9 was performed by crystallization from concentrated aqueous solutions of disodium 5,5′‐azobis[1H‐tetrazol‐1‐ide] dihydrate (Na2ZT⋅2 H2O; 1) and the respective Ln(NO3)3⋅5 H2O and yielded large rhombic crystals of the type [Ln(H2O)8]2(ZT)3⋅6 H2O in ca. 70% of the theoretical yield. The compounds 3–9 are isostructural (triclinic space group P$\bar 1$) to the previously published yttrium salt 2; they show, however, a clear lanthanoid contraction of several crystallographic parameters, e.g., the cell volume or the LnO bond lengths of the Ln3+ ions and the coordinating H2O molecules. The lanthanoid contraction influences the strengths of the H‐bonds, which can be observed as a red shift by 4 cm−1 in the characteristic IR band, in particular from 3595 cm−1 (3) to 3599 cm−1 (9). In good agreement with previous works, 2–9 are purely salt‐like compounds without a coordinative bond between the tetrazolide anion and the Ln3+ cation.
Upregulated claudin‐1 expression confers resistance to cell death of nasopharyngeal carcinoma cells
Authors: Lee Jeng‐Woei , Hsiao Wei‐Ting , Chen Hsia‐Yun , Hsu Lee‐Ping , Chen Peir‐Rong , Lin Ming‐Der , Chiu Shu‐Jun , Shih Wen‐Ling , Hsu Yih‐Chih 
Published: September 2009

AbstractAccumulating evidence reveals that aberrant expression of claudins manifests in various tumors; however, their biological functions are poorly understood. Here, we report on the elevated expression of claudin‐1 in nasopharyngeal carcinoma (NPC) cell lines under serum deprivation or fluorouracil (5‐FU) treatment. Interestingly, an increase in expression of claudin‐1 considerably reduced apoptosis rather than enhancing cell proliferation. However, claudin‐1 expression and activity were unaffected by external stimuli or Akt and NF‐κB activation. Notably, predominant cytoplasmic and nuclear localization of claudin‐1 in NPC cells reflected the aforementioned feature. On the other hand, loss of epithelial morphology and E‐cadherin expression was associated with serum withdrawal in NPC cells. Interestingly, restoration of E‐cadherin inhibited the protein elevation and antiapoptotic activity of claudin‐1. In conclusion, our data demonstrate the regulation and novel biological function of claudin‐1 and indicate the important role of claudin‐1 in NPC tumorigenesis.
Hospicells derived from ovarian cancer stroma inhibit T‐cell immune responses
Authors: Martinet Ludovic , Poupot Rémy , Mirshahi Pejman , Rafii Arash , Fournié Jean‐Jacques , Mirshahi Massoud , Poupot Mary 
Published: September 2009

AbstractWith metastatic disease at diagnosis for 70% of patients, ovarian cancer represents the most lethal gynecological malignancy. Ovarian carcinomas are aggressive malignancies that can evade immune surveillance and frequently develop into metastases. The tumor microenvironment is decisive for preventing immune attack but, in the case of ovarian carcinoma, the mechanisms are unclear. We recently isolated a novel type of stromal cell from the ascitis of patients with ovarian carcinoma that interacts with epithelial ovarian cancers conferring them chemoresistance. These cells, called Hospicells, have the cell surface markers CD9, CD10, CD29, CD146 and CD166. Here, we investigated whether Hospicells also have immunomodulatory functions that might interfere with immunity to cancer. We report that Hospicells inhibit the proliferation of human CD4+, CD8+ and Vγ9Vδ2 T cells in vitro and the production of cytokines by these immune cells. The immunosuppression of CD4+ T cells is independent of direct contact with the Hospicells and is mainly due to nitric oxide produced by the inducible nitric oxide synthase and to products of the tryptophan degradation by indoleamine 2,3‐dioxygenase. We proposed that Hospicells in the microenvironment of the tumor mediate immunosuppression of T cells and thus allow ovarian cancers to evade immune surveillance. Targeting of Hospicells could be an alternative to strong chemotherapy through the recovery of immune responses against tumor cells.