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Academic literature on the topic 'Mrk 348'

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Published: 9 March 2023
Last updated: 10 March 2023

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Journal articles on the topic "Mrk 348"

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Peck, Alison B., Heino Falcke, Christian Henkel, Karl M. Menten, Yoshiaki Hagiwara, Jack F. Gallimore, and James S. Ulvestad. "A flaring megamaser in Mrk 348." Symposium - International Astronomical Union 206 (2002): 434–37. http://dx.doi.org/10.1017/s0074180900222845.

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We report new observations of the H2O megamaser in the Seyfert 2 galaxy Mrk 348. Following our initial detection in 2000 March using the Effelsberg 100 m telescope, a re-analysis of previous data on this source indicates that the maser was present but only marginally detectable in late 1997. Monitoring through late 2000 shows that the maser has again decreased to its original level. The H2O line is redshifted by ∼130 km s−1 with respect to the systemic velocity, is extremely broad, with a FWHM of 130 km s−1, and has no detectable high velocity components within 1500 km s−1 on either side of the strong line. Followup VLBA observations show that the maser emission emanates entirely from a region ≤0.25 pc in extent, toward the base of the radio jet.
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Riffel, R. A., O. L. Dors, M. Armah, T. Storchi-Bergmann, A. Feltre, G. F. Hägele, M. V. Cardaci, et al. "Chemical abundances in Seyfert galaxies – V. The discovery of shocked emission outside the AGN ionization axis." Monthly Notices of the Royal Astronomical Society: Letters 501, no. 1 (December 8, 2020): L54—L59. http://dx.doi.org/10.1093/mnrasl/slaa194.

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ABSTRACT We present maps for the electron temperature in the inner kpc of three luminous Seyfert galaxies: Mrk 79, Mrk 348, and Mrk 607 obtained from Gemini Multi-Object Spectrograph-integral field unit observations at spatial resolutions of ∼110–280 pc. We study the distributions of electron temperature in active galaxies and find temperatures varying in the range from ∼8000 to $\gtrsim 30\, 000\,$K. Shocks due to gas outflows play an important role in the observed temperature distributions of Mrk 79 and Mrk 348, while standard photoionization models reproduce the derived temperature values for Mrk 607. In Mrk 79 and Mrk 348, we find direct evidence for shock ionization with overall orientation orthogonal to the ionization axis, where shocks can be easily observed as the active galactic nuclei radiation field is shielded by the nuclear dusty torus. This also indicates that even when the ionization cones are narrow, the shocks can be much wider angle.
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Capetti, A., D. J. Axon, F. D. Macchetto, and W. B. Sparks. "Radio Outflows and the Origin of the Narrow Line Region in Seyfert Galaxies." Symposium - International Astronomical Union 175 (1996): 230–31. http://dx.doi.org/10.1017/s0074180900080591.

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Seven Seyfert galaxies, Mrk 3, Mrk 78, Mrk 348, Mrk 6, Mrk 573, NGC 3393, IRAS 04210+0400 and IRAS 11058-1131 (all Seyfert galaxies type 2 expect Mrk 6 which is a Seyfert 1.5) were observed with HST. For the first five objects images were taken with the FOC with filters centered on the emission lines [O II] and [O III]. For the remaining three galaxies WFPC2 observations were obtained in the [O III] and Hα lines.
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Riffel, Rogemar A., Oli L. Dors, Angela C. Krabbe, and César Esteban. "Electron temperature fluctuations in Seyfert galaxies." Monthly Notices of the Royal Astronomical Society: Letters 506, no. 1 (June 10, 2021): L11—L15. http://dx.doi.org/10.1093/mnrasl/slab064.

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ABSTRACT We use Gemini GMOS-IFU observations of three luminous nearby Seyfert galaxies (Mrk 79, Mrk 348, and Mrk 607) to estimate the electron temperature (Te) fluctuations in the inner 0.4–1.1 kpc region of these galaxies. Based on Te determinations through the [O iii]λ5007/λ4363 emission line ratio of each spaxel, temperature variations are quantified by computing the integrated value of the temperature fluctuation parameter (t2) projected in the plane of the sky $t_{\rm A}^{\rm 2}$, for the first time in active galactic nuclei (AGNs). We find $t_{\rm A}^{\rm 2}$ values of 0.135, 0.039, and 0.015 for Mrk 79, Mrk 348, and Mrk 607, respectively, which are of the same order or larger than the maximum values reported in star-forming regions and planetary nebulae. Taking into account that $t_{\rm A}^{\rm 2}$ should be considered a lower limit of the total t2 in the nebular volume, the results suggest that the impact of such fluctuations on chemical abundance determinations can be important in some AGNs.
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Antón, Sónia, Andrew Thean, Ian Browne, and Alan Pedlar. "The orientation of the Seyfert Nucleus in Mrk 348." International Astronomical Union Colloquium 184 (2002): 289–90. http://dx.doi.org/10.1017/s0252921100030840.

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AbstractWe present new data on Mrk348: 5 GHz data with MERLIN and infrared data with ISO. The radio properties of Mrk 348 are unusual among Seyfert galaxies, and we discuss the orientation of the AGN axis with respect to the line of sight.
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Marchese, E., V. Braito, J. N. Reeves, R. Della Ceca, A. Caccianiga, A. Markowitz, G. Risaliti, P. Severgnini, and T. J. Turner. "The variable ionized absorber in the Seyfert 2 Mrk 348." Monthly Notices of the Royal Astronomical Society 437, no. 3 (November 30, 2013): 2806–15. http://dx.doi.org/10.1093/mnras/stt2101.

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Xanthopoulos, Emily, Anita M. S. Richards, and Phil J. Diamond. "Merlin water maser observations of the Seyfert 2 galaxy Mrk 348." Symposium - International Astronomical Union 206 (2002): 438–41. http://dx.doi.org/10.1017/s0074180900222857.

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MERLIN images of Mrk 348 at 22 GHz show H2O maser emission at 0.02–0.11 Jy, within ∼ 0.8 pc of the nucleus. This is the first direct confirmation that molecular material exists close to the Seyfert 2 nucleus. Mrk 348 was observed one month after Falcke et al. (2000) first identified the maser in single-dish spectra. The peak maser flux density has increased about threefold. The masing region is ≲ 0.6 pc in radius. The flux density of radio continuum emission from the core has been rising for about 2 years. The maser-core separation is barely resolved but at the 3σ significance level maser and continuum peaks are not coincident along the line of sight. The masers lie in the direction of the northern radio lobes and probably emanate from material shocked by a jet with velocity close to c although direct maser amplification of the core by masers tracing a Keplerian disc is not completely ruled out.
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Wang, J., J. S. Zhang, and Q. Guo. "Chandra and XMM–Newton Observations of H2O Maser Galaxy Mrk 348." Journal of Astrophysics and Astronomy 35, no. 3 (September 2014): 545–48. http://dx.doi.org/10.1007/s12036-014-9282-0.

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Macchetto, F. Duccio. "HST Observations of Active Galactic Nuclei." Symposium - International Astronomical Union 194 (1999): 12–24. http://dx.doi.org/10.1017/s0074180900161674.

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The HST has made many contributions to all areas of research in the field of AGN, and I have selected three topics where major progress in our understanding has been made over the last two years. The study of the NLR is key to understanding to what extent the unified model for AGN is applicable. In particular, understanding how the NLR is ionized and how its morphology is defined makes an important contribution to clarify the differences between Seyfert 1 and Seyfert 2. Work by Macchetto et al., Capetti et al., Axon et al., and Wilson et al. has helped clarify the picture. Our work on NGC 1068, Mrk 3, Mrk 7, Mrk 348, Mrk 6, and Mrk 573 has shown the following important properties: a) all AGN with a linear radio jet show emission-line morphology ([O III], [O II], Hα) which is aligned along the jet in a surrounding cocoon; b) those AGN with radio lobes show emission-line morphology which is filamentary and coincident with the position of the lobes; and c) in NGC 1068 and in Mrk 3 we have measured transverse velocities to the radio-jet as large as 1700 km s−1. These velocities measured at different positions across the radio-jet show an almost perfect velocity ellipsoid, indicating that the cocoon around the jet is expanding, compresses the ISM and shocks and ionizes the region.
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Maloney, Philip. "Variability of Water Megamasers in AGN." Publications of the Astronomical Society of Australia 19, no. 1 (2002): 88–90. http://dx.doi.org/10.1071/as01106.

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AbstractPowerful water masers have been detected in 23 active galactic nuclei (AGN) to date. Most of the sources that have been monitored show evidence for variability, which may be either intrinsic (response of the masers to a time-varying pump or background source) or extrinsic (the effects of scintillation in the interstellar medium of the Galaxy). I briefly review the examples in which these mechanisms may be operating (interstellar scintillation in the Circinus galaxy, a time-varying background source in Mrk 348, and a time-varying AGN luminosity in NGC 1068).
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Dissertations / Theses on the topic "Mrk 348"

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MARCHESE, ELENA. "X-ray absorption in Active Galactic Nuclei." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/89114.

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I Nuclei Galattici Attivi (AGN) sono tra le sorgenti più luminose dell’Universo e sono osservati in circa 10-20% delle galassie nell’Universo locale. Il meccanismo di generazione dell’energia di queste sorgenti è l’accrescimento di materia su un buco nero supermassivo (SMBH). Secondo il paradigma del Modello Unificato (UM) il SMBH è circondato da un assorbitore uniforme e anisotropo di gas e polveri, con geometria toroidale, che si estende da 1pc a 100pc. Anche se a livello generale l’UM è corretto, lavori recenti hanno evidenziato la necessità di formulare modelli alternativi per spiegare ad esempio la presenza di molteplici assorbitori disomogenei, a diverse distanze dal SMBH e in diversi stati fisici. Tra le argomentazioni in conflitto con l’UM vi è la variabilità spesso osservata negli spettri X degli AGN. Quando non deriva da una variazione intrinseca dell’emissione nucleare, essa implica che l’assorbitore è ‘’clumpy’’ e non è uniforme. Vari studi hanno anche mostrato che l’assorbitore non è sempre neutro: sono stati osservati outflow di grandi quantità di materiale parzialmente ionizzato (noti come “warm absorbers”) con velocità di outflow tra 100 e 1000 km/s, in circa il 50% degli AGN di tipo 1. Un’ulteriore complessità è rappresentata dalle osservazioni di assorbitori altamente ionizzati con alte velocità di outflow (vout>3000 km/s) noti come “ultrafast outflows”. La mia tesi si occupa della variabilità di assorbimento osservata negli spettri X degli AGN, fondamentale per testare le dimensioni, la struttura e la composizione della materia circumnucleare. In dettaglio, ho analizzato lo spettro X di due AGN, NGC 454E e Mrk 348, per cui sono disponibili dati dei satelliti Swift-BAT, Suzaku e XMM-Newton. NGC 454E è una galassia di Seyfert 2, parte di un sistema di galassie interagenti, a z=0.0122. Confrontando gli spettri di Suzaku e XMM, con distanza temporale di 6 mesi, ho notato un forte cambiamento della curvatura spettrale tra 3 keV e 6 keV. La sua origine è riconducibile a una variazione importante della densità colonnale dell’assorbitore neutro, che ha permesso di classificare NGC 454E come “changing-look AGN”. Inoltre, lo spettro di XMM mostra segni della presenza di un assorbitore ionizzato, assente durante l’osservazione di Suzaku, con un limite superiore sulla distanza di circa 0.001 pc. Mrk 348 è una galassia classificata come Seyfert 2, a z=0.015. Il suo spettro è caratterizzato da tre diversi assorbitori, uno neutro e due ionizzati, con diverse densità e stati di ionizzazione, ma con circa la stessa velocità di outflow (∼0.05c). Le distanze degli assorbitori ionizzati dal SMBH sono probabilmente differenti, in quanto i limiti superiori sono trovati essere di 0.026pc per l’assorbitore di più alta ionizzazione e 2.72pc per quello di media ionizzazione. Anche Mrk 348 presenza una variazione della densità colonnale tra Suzaku e XMM, sia per l’assorbitore neutro che per quello di media ionizzazione. Questi studi costituiscono un passo in avanti per definire un modello alternativo all’UM, per cui ci sono sempre più prove che la regione circumnucleare è composta da diversi assorbitori, a diverse distanze e stati di ionizzazione.
Active Galactic Nuclei (AGN) are among the most energetic sources in the Universe, and they are observed in about 10-20% of the galaxies in the local Universe. Their energy generation mechanism is accretion of matter on a central Supermassive Black Hole (SMBH). According to the most accredited paradigm, the Unified Model (UM), the SMBH is surrounded by an anisotropic uniform absorber of gas and dust, with a toroidal geometry, extending from 1 pc to 100 pc. Even if on a basic level the UM is correct, the need for alternative models was highlighted by the detection of several dishomogeneous absorbers, located at different distances from the SMBH, and at different physical states. Among the arguments in conflict with the UM there is the variability often observed in the X-ray spectra of AGN. When not resultant from an intrinsic variation of the nuclear emission, it implies that the underlying absorber is clumpy and not uniform. Many studies also showed that, besides being clumpy, the absorbing material is not always completely neutral. Significant amounts of outflowing partially-ionized material have been detected in about ∼50% of Type 1 AGN. These ionized absorbers are called “warm absorbers” and have outflow velocities in the range ∼100−1000 km/s. Furthermore, highly ionized absorbers with high outflow velocities (vout>3000 km/s, “ultrafast outflows”) have been observed. This thesis focuses on observations of absorption variability in the X-ray spectra of AGN, as a useful “tool” to test the size, structure and composition of the circumnuclear medium. In detail, I analysed the X-ray spectra of two AGN, NGC 454E and Mrk 348, for which X-ray data from Swift-BAT, Suzaku and XMM-Newton were available. NGC 454E is a red elliptical Seyfert galaxy in an interacting system, at z=0.0122. When comparing the Suzaku and XMM-Newton spectra, observed with 6 months delay, I noticed a dramatic change in the spectral curvature between 3 keV and 6 keV. The origin of the variability was due to a strong change of the column density of a neutral absorber, that allowed to classify NGC 454E as a “changing-look AGN”. Moreover, the XMM-Newton spectrum showed clear signatures of the presence of an ionised absorber, absent during Suzaku observation. An upper limit on its distance was inferred to be ∼0.001 pc. Mrk 348 is a bright Compton-thin Seyfert 2 galaxy at z=0.015. I found that its spectrum is characterized by three different absorbers, one neutral and two ionised, with different densities and ionisation states, but with approximately the same outflow velocity (∼0.05c). The distances of the ionised absorbers from the central emitting region are likely to be different, indeed the upper limits I find are 0.026 pc for the highly ionised absorber, and 2.72 pc for the mildly ionised one. A variation of the column density is present also for Mrk 348, both for the neutral absorber and for the mildly ionized. Both these studies are a step forwards in the definition of an alternative model to the UM, for which more and more evidences are being collected, denoting that the absorbing material is composed by multiple absorbers at different distances, densities and ionization states.
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Santoja, Jakub. "The sense of a beginning : Bakhtinian dialogic criticism on 'the Gospel' in Mark." Thesis, University of Sheffield, 2000. http://etheses.whiterose.ac.uk/3489/.

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Contemporary literary approaches have caused paradigm shifts in Biblical Studies in the last two decades as it appears in a great deal of Markan studies using narrative, reader-response, deconstructive, feminist, and new historicist approaches. However, literary studies on the Gospel of Mark have not taken into account theoretical questions underlying those approaches. As a result biblical critics are driven by new trends without ever having a chance to examine the critical baggage of the approaches. Consequently, there is a gap of communication between the old and the new one. Therefore this thesis is an attempt to meet the need of enhancing the quality of critical endeavour in biblical studies. In the light of most recent competing critical theories of literature, the first contribution of this thesis is the methodological finding that Bakhtinian dialogic criticism contains the most profound philosophical and practical foundations for solving some crucial theoretical problems in contemporary literary theories. It is a critique to a Saussurian linguistic system of language which becomes the very foundation of modern and postmodern literary criticism. Bakhtinian literary theory shifts the foundation of literary criticism on linguistic signs into the creative activity of the socio-cultural production of human communication. The shift into socio-cultural reality of language communication makes the notion of 'genre' very important to unlock the problem of text and context in literary studies. Since the Gospel of Mark has fascinated most literary critics in Biblical Studies, the problem of 'genre' of this gospel is chosen as the focus of this study. Secondly, as no agreement is reached as to what 'genre' the Gospel of Mark belongs, this thesis makes its contribution to the discussion by locating the problem of 'genre' of Mark in the context of genre theories and argues that the Bakhtinian suggestion to find genre in the socio-cultural sphere by analysing artistic intercourse between narrative agents in Mark has freed the competing analysis from the unresolved problem between the kerygmatic (content oriented) approach and the analogical (form oriented) approach. To achieve finding 'genre' in the socio-cultural sphere, this thesis focuses on Bakhtinian analysis of the process of artistic intercourse between narrative agents. The narrative communicative interrelationships between narrative agents is constructed in this thesis as a 'stereophonic' Bakhtinian model of dialogic communication. This model is an original contribution of this thesis for revising the traditional two dimensional model of narrative communication. Based on this dialogical model of communication, a special role is given to the Bakhtinian 'author-creator' in the realization process of genre through the interaction of polyphonic voices. Through the interaction of voices of the author-artist and the hero we are led to discover a relatively stable type of portraying and controlling reality in Mark, known as the genre of Roman 'satire'. The closest literary affinity is Satyrica by Petronius. This narrative strategy of 'satire' in Mark has its root in the prophetic discourse of the Old Testament which is saturating the speech of the narrator, John the Immerser, the centurion, the people, and even Jesus. Finally, the whole search for Markan 'genre' culminates in the analysis of the realization of genre through the analysis of Bakhtinian chronotope. The reality of the genre of Mark is its social reality that is in its role as dpxrj/ 'beginning'. As the Gospel of Mark proclaims itself as 'a beginning', it defines its claim of socio-cultural 'authority' in early Christianity. It is this 'sense of beginning' which enables the narrating and the narrated world of Mark to interact dialogically.
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Yang, Guojun. "Miniature inverted repeat transposable elements in rice - origin and function." Texas A&M University, 2004. http://hdl.handle.net/1969.1/318.

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Transposable elements (TEs) are interspersed repetitive sequences that are present in most genomes. Miniature inverted repeat transposable elements (MITEs) are the most numerous Class II elements in higher eukaryotes. Little is known about their origin, transposition and function. In this study, three novel MITE families (Kiddo, MDM1 and MDM2) were identified in the rice genome. They bear terminal inverted repeats (TIRs) and show target site duplications (TSDs) at the insertion sites. Each family is present in hundreds of copies with length that range from 200 bp to 400 bp. An evolutionary relationship between Mutator elements and MDM1 and MDM2 family was established. The absence of an observed transposition event, together with the mutated ancestral elements identified by in silico analysis, led to a conclusion that Kiddo and its autonomous elements are not presently active. To overcome laborious and time consuming manual analysis of MITEs on a genomic scale, MAK, a computational tool kit, was developed to automatically retrieve MITE sequences, their neighboring genes and ancestral elements from genome sequences. MAK has been functionally tested and is now available to the research community. Studies on the effect of MITE (Kiddo and MDM1) insertions into a rice ubiquitin (rubq2) promoter revealed a two-edged role of MITEs on gene regulation. While Kiddo and MDM1 contribute ~40% to rubq2 promoter activity, they also induce progressive silencing of this promoter. The evolutionary implications of the two-edged role of MITEs in gene regulation are discussed.
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Simpson, Richard. "How to Tell a Story: Mark Twain and the Short Story Genre." TopSCHOLAR®, 2007. http://digitalcommons.wku.edu/theses/378.

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This study examines the short fiction of Mark Twain in relation to major theories concerning the short story genre. Despite his popularity as a novelist and historical figure, Twain has not been recognized as a major figure in the development of the short story genre. This study attempts to show that the short fiction produced by Twain deserves greater regard within studies specific to the short story, and calls for a reconsideration of Twain as a dynamic figure in the development of the genre. The introductory chapter lays the groundwork for understanding how the short story genre has developed since its inception as an actual literary genre, and outlines the existing Twain scholarship concerning his short fiction. Differences between the traditional and modern forms of the short story are defined, and Twain's chronological position in the evolution of the genre is briefly explained. Chapter one examines two of Twain's short stories—"The $30,000 Bequest" and "The Man That Corrupted Hadleyburg"—in relation to the compositional theories of the first major short story theorist: Edgar Allan Poe. This chapter shows how these two Twain stories abide by Poe's rules concerning unity of effect. Chapter two explores Twain's "Journalism in Tennessee" and "The Notorious Jumping Frog of Calaveras County" in relation to the modern short story, and examines these two stories through the lens of Mikhail Bakhtin's theories of genre. This chapter closely examines Twain's use of various dialects to show that these two stories contain an unrealized complexity and are very closely related to the ostensibly "plotless" short fiction that developed in the twentieth century. The final chapter takes Twain's "The Mysterious Stranger" and examines it with respect to both old and new theories of the short story genre. This chapter shows how "The Mysterious Stranger" fuses both traditional and modern forms of the short story genre. The conclusion to this chapter reiterates the argument for a greater appreciation of Twain as a short story artist.
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Li, Gang. "Robotic System Development for Precision MRI-Guided Needle-Based Interventions." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-dissertations/341.

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"This dissertation describes the development of a methodology for implementing robotic systems for interventional procedures under intraoperative Magnetic Resonance Imaging (MRI) guidance. MRI is an ideal imaging modality for surgical guidance of diagnostic and therapeutic procedures, thanks to its ability to perform high resolution, real-time, and high soft tissue contrast imaging without ionizing radiation. However, the strong magnetic field and sensitivity to radio frequency signals, as well as tightly confined scanner bore render great challenges to developing robotic systems within MRI environment. Discussed are potential solutions to address engineering topics related to development of MRI-compatible electro-mechanical systems and modeling of steerable needle interventions. A robotic framework is developed based on a modular design approach, supporting varying MRI-guided interventional procedures, with stereotactic neurosurgery and prostate cancer therapy as two driving exemplary applications. A piezoelectrically actuated electro-mechanical system is designed to provide precise needle placement in the bore of the scanner under interactive MRI-guidance, while overcoming the challenges inherent to MRI-guided procedures. This work presents the development of the robotic system in the aspects of requirements definition, clinical work flow development, mechanism optimization, control system design and experimental evaluation. A steerable needle is beneficial for interventional procedures with its capability to produce curved path, avoiding anatomical obstacles or compensating for needle placement errors. Two kinds of steerable needles are discussed, i.e. asymmetric-tip needle and concentric-tube cannula. A novel Gaussian-based ContinUous Rotation and Variable-curvature (CURV) model is proposed to steer asymmetric-tip needle, which enables variable curvature of the needle trajectory with independent control of needle rotation and insertion. While concentric-tube cannula is suitable for clinical applications where a curved trajectory is needed without relying on tissue interaction force. This dissertation addresses fundamental challenges in developing and deploying MRI-compatible robotic systems, and enables the technologies for MRI-guided needle-based interventions. This study applied and evaluated these techniques to a system for prostate biopsy that is currently in clinical trials, developed a neurosurgery robot prototype for interstitial thermal therapy of brain cancer under MRI guidance, and demonstrated needle steering using both asymmetric tip and pre-bent concentric-tube cannula approaches on a testbed."
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Sicard, Kenneth M. "Multimodal MRI, Behavioral Testing, and Histology in a Rat Model of Transient Focal Cerebral Ischemia : A Dissertation." eScholarship@UMMS, 2006. http://escholarship.umassmed.edu/gsbs_diss/318.

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Cerebral ischemia is defined as a decrease in blood flow to the brain. It is most often caused by obstruction of a cerebral blood vessel, and is recognized by the World Health Organization as the leading cause of serious adult disability and one of the top three causes of adult death worldwide. Most survivors demonstrate partial restitution of function over time, but the underlying recovery mechanism(s) remain unclear especially in a subset of patients with persistent neurological morbidities despite normal-appearing brain on neuroimaging. The optimal way to understand any human disease state is via clinical studies. Unfortunately, well-controlled experiments in humans are difficult due to small patient populations, the presence of numerous confounding variables, and ethical issues associated with invasive or discomforting experimental procedures. Anesthetized animal models of cerebral ischemia afford a means of avoiding the above difficulties. However, anesthesia and physiological perturbations that occasionally follow brain ischemia may affect the reliability of certain tools used to study this disease, such as functional magnetic resonance imaging (fMRI). Therefore, the central goals of this thesis were: 1) to evaluate the feasibility of performing fMRI in anesthetized and awake animals, 2) to assess fMRI responses under various perturbations of cerebral perfusion and tissue oxygenation in order to identify key factors that may modulate functional signal changes following ischemia, and 3) to utilize fMRI, behavioral tests and histology in an anesthetized animal model of transient focal cerebral ischemia to explore postischemic changes in brain pathology/function and how they relate to changes in behavior. In the first study of this dissertation, I report the evaluation of fMRI responses in anesthetized and awake animals. Anesthesia is frequently used in animal models of cerebral ischemia, but is known to alter brain perfusion and metabolism which may, in turn, affect fMRI responsivity. Perfusion-based fMRI was used to evaluate cerebral blood flow (CBF) and blood oxygenation level-dependent (BOLD) responses to hypercapnia in awake and isoflurane-anesthetized rats. Hypercapnia produced significant CBF and BOLD fMRI signal changes throughout the cerebrum in awake and isoflurane-anesthetized groups. These results show that perfusion-based fMRI can successfully detect stimulus-evoked hemodynamic changes in the brains of both conscious and isoflurane-anesthetized animals. The second study of this dissertation: 1) investigates the effects of alterations in cerebral perfusion and oxygenation on fMRI signal changes, and 2) examines the self-consistency of an imaging-based formalism for the calculation of the cerebral metabolic rate of oxygen (CMRO2). Functional MRI responses to a stimulus can be described in terms of relative or absolute signal change. A relative fMRI response is defined as a percent-change relative to its own respective baseline value. An absolute fMRI response is defined as a quantitative change relative to a single fixed baseline value that serves as a control. Thus, an absolute fMRI signal change is largely independent of the baseline state and may more accurately index brain activity when baseline fMRI signals change significantly over time due to, for example, hemodynamic-metabolic disturbances that occur during and/or after brain ischemia. To address these issues, the effects of inspired hypoxic, normoxic, hyperoxic, and hypercapnic gases on baseline and forepaw stimulation-evoked changes in BOLD and CBF fMRI signals were examined in isoflurane-anesthetized rats. Relative fMRI responses to forepaw stimulation varied-whereas. absolute responses were similar--across gas conditions. These results demonstrate that absolute measurements of fMRI signal change may lend a more accurate measure of brain activity during states of altered basal physiology as well as support the self-consistency of the imaging-based CMRO2 formalism under these conditions. The third and last study of this dissertation utilized multimodal MRI, behavioral tests, and histology at acute to chronic periods following transient middle cerebral artery occlusion (tMCAO) in the rat to examine the evolution of pathological, functional, and behavioral parameters following transient focal cerebral ischemia. MRI was used to track the evolution of brain pathology and function following cerebral ischemia, and it was found that the cerebral sensorimotor network, critical for sensory and motor behavioral functions, showed profoundly abnormal signal changes that required up to one day to normalize. Adhesive removal, forepaw placement and beam-walk behavioral tests demonstrated sensorimotor dysfunctions that gradually improved but remained long after the recovery of MRI parameters. Postmortem histology confirmed the presence of selective neural cell death within the sensorimotor network at time points when behavior was abnormal. These results suggest that subtle postischemic pathological changes in the brain undetectable by MRI may be responsible for persistent behavioral deficits-a finding which may be relevant to a clinical subset of patients with persistent neurological morbidities despite negative MRI results following cerebral ischemia.
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Pardo, Pardo Raül. "Studies on the molecular mechanisms of cell proliferation: phosphatidylcholine-derived lipids and lithium modulation of the MEK/ERK pathway." Doctoral thesis, Universitat Autònoma de Barcelona, 2003. http://hdl.handle.net/10803/3488.

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Las fosfolipasas D (PLDs) son enzimas regulables que catalizan la hidrólisis de la fosfatidilcolina, un fosfofolípido mayoritario de las membranas de células eucariotas, para dar lugar a fosfatidato (PtdOH), molécula capaz de funcionar como segundo mensajero y que se ha implicado en procesos celulares como el tráfico vesicular, la reorganización del citoesqueleto y la proliferación celular. Los alcoholes primarios, como el 1-butanol, pueden derivar la formación de PtdOH por la PLD hacia la formación de los correspondientes fosfatidilalcoholes (moléculas inactivas). Es por ello que los alcoholes primarios son ampliamente usados en el estudio de las funciones celulares en las que se hayan implicados enzimas PLD. Esta tesis se centra en el estudio de procesos celulares en los que intervienen enzimas PLD, y en particular, el estudio de su implicación en el ondulamiento de la membrana plasmática (membrane ruffling) y en la proliferación celular.
El ondulamiento de la membrana plasmática es un proceso dinámico que requiere del reordenamiento del citesqueleto de actina. Es fácilmente observable en células especializadas en secreción e indicativo de que la célula está exocitando activamente. Tanto mastocitos como línias celulares relacionadas responden a la estimulación por antígenos con una reorganización profunda de su citoesqueleto cortical y con la exocitosis de sus gránulos de secreción. Nosotros hemos observado que la inhibición de la formación de PtdOH por la PLD mediante la incubación con 1-butanol se traduce en la inhibición de la ondulación de la membrana plasmática en células RBL-2H3 (una línea celular mastocitaria). Dicha inhibición por 1-butanol es totalmente reversible: si se elimina el 1-butanol del medio las células recuperan la capacidad de ondular su membrana plasmática en respuesta a la estimulación por antígeno. Medidas de la actividad PLD en respuesta a antígeno indican que la ondulación de la membrana requiere de la producción continua de PtdOH por la PLD. Tanto PLD1 como PLD2 son expresadas por células RBL. En estudios de transfección con PLD1 y PLD2 marcadas con GFP (green fluorescent protein) se observa la colocalización de PLD2 en las ondulaciones de membrana de células RBL estimuladas con antígeno. Por contra, GFP-PLD1 muestra una distribución intracelular localizada en vesículas citoplasmáticas. Por ello asumimos que la isoforma PLD2 es esencial en los cambios a nivel de citoesquelto que se observan en respuesta a la estimulación por antígeno.
En el estudio de la implicación de la PLD en la proliferación celular se emplearon astrocitos en cultivo como modelo celular. Se determinó la activación de la PLD en respuesta a una batería de estímulos incluyendo el promotor de tumores PMA, factores de crecimiento y agonistas de receptores metabotrópicos. Asimismo, se deteminó la estimulación de la incorporación de timidina al DNA como reflejo de la actividad mitogénica en respuesta a los mismos estímulos. Observamos una clara ausencia de correlación entre la activación de la PLD y la magitud de la respuesta mitogénica. De este dato concluimos que la formación de PtdOH por la PLD no parece ser un mecanismo comunmente implicado en la transducción de señales proliferativas. Por otra parte, la inhibición de la formación de PtdOH (por incubación en presencia de alcoholes primarios) no se traduce en la reducción de la actividad proliferativa en respuesta a diversos mitógenos, apoyando la conclusión anterior.
Tras concluir que la activación de la PLD no era un requerimiento necesario en la transducción de señales mitogénicas, nos propusimos explorar mecanismos moleculares implicados en la proliferación de astrocitos. Observamos que concentraciones de litio en el rango milimolar inducen un bloqueo en el ciclo celular a nivel de G2/M en astrocitos proliferantes. Asimismo, el litio retrasa la progresión a través del ciclo celular en astrocitos deprivados de suero y estimulados por el mitógeno endotelina-1. La adición exógena de myo-inositol no es capaz de revertir los efectos del litio sobre el ciclo celular y estos no se reproducen por la inhibición selectiva de la glucógeno sintasa quinasa-3 (GSK3). Estos resultados sugieren que los efectos del litio no son mediados ni por inhibición de inositol monofosfatasas ni por inhibición de GSK3, dos de sus dianas farmacológicas reconocidas. Por contra, el pretratamiento con litio de astrocitos proliferantes reduce la activación de ERK1/2 (extracellular regulated kinase 1/2) y de su quinasa reguladora MEK 1/2. El litio priviene también la activación de dichas quinasas en respuesta a endotelina-1 en astrocitos deprivados de suero. En células granulares de cerebelo concentraciones milimolares de litio promueven la activación de MEK y ERK. Los efectos opuestos del litio en neuronas y astrocitos nos llevan a proponer su uso terapeútico en situaciones de daño traumático en el sistema nervioso central.
Phospholipase Ds (PLDs) are regulated enzymes that catalyse the hydrolysis of phosphatydylcholine, a major lipid contituent of eukaryotic cell membranes, and generate phosphatidic acid (PtdOH), a putative second messenger molecule implicated in the regulation of vesicular trafficking, cytoskeletal reorganisation and cell proliferation. Primary alcohols such as butan-1-ol can divert the production of PtdOH generated by PLD to the correspondent phosphatydylalcohol (inactive molecule) and therefore constitute useful tools in the study of cellular functions of PLD enzymes. The present thesis aims to explore the role of PLD in different cellular events, in particular in membrane ruffling and in cell proliferation.
Membrane ruffling is a dynamic phenomenon taking place at the plasma membrane that requires the rearrangement of the actin cytoskeleton. It is very prominent in cells specialised in secretion and is indicative of ongoing exocytosis. Mast cells and related cell lines, when stimulated with antigen, show a dramatic alteration of their cytoskeleton required for the release of secretory granules by exocytosis. We have observed that inhibition of PLD-derived PtdOH fomation by butan-1-ol results in the halt of antigen-stimulated membrane ruffling in a mast cell line (RBL-2H3 cells). Inhibition by butan-1-ol was completely reversible because its removal restored membrane ruffling. Measurements of PLD activation by antigen indicate a requirement for continual PtdOH formation during ruffling. PLD1 and PLD2 are both expressed in RBL cells and green fluorescent-tagged (GFP) proteins were used to identify PLD2 localizing to membrane ruffles in antigen-stimulated RBL cells. In contrast, GFP-PLD1 localised in intracellular vesicles and remained in this location after stimulation with antigen. We therefore assume that PLD2 is essential for actin cytoskeletal rearrangements triggered by antigen.
The role of PLD in cell proliferation was studied in cultured astrocytes. We monitored PLD activation elicited by a set of different stimuli including the tumour promoter PMA, growth factors and G protein-coupled receptor agonists. As an index of the mitogenic response, thymidine incorporation into DNA in response to these stimuli was also monitored. We observed a lack of correlation between PLD activation and the extent of the mitogenic response, suggesting that PtdOH formation was not a common mechanism involved in mitogenic signal transduction. In agreement with this conclusion, primary alcohol inhibition of PtdOH formation by PLD does not result in the inhibition of the mitogen-stimulated incorporation of thymidine into DNA.
Having observed that PLD may not be part of the mitogenic signal transduction machinery, we further explored molecular mechanims involved in astrocyte proliferation. We observed that millimolar lithium concentrations induced a G2/M cell cycle arrest in proliferating astrocytes and also delays cell cycle reentry by the mitogen endothelin-1. Myo-inositol supplementation of the culture medium could not overcome lithium-induced cell cycle arrest and selective inhibition of glycogen synthase kinase-3 (GSK3) by compound SB216763 could not reproduce lithium effects on cell cycle distribution. This results indicate that lithium effects are unlikely mediated by inhibition of inositol monophosphate phosphatases nor GSK3 inhibition, two pharmacological targets mediating lithium actions in other settings. Interestingly, lithium pretreatment of proliferating astrocytes results in reduced phosphorylaton of extracellular regulated kinase 1/2 (ERK1/2) and the upstream kinase MEK1/2. Lithium also prevents endothelin-1-stimulated phosphorylation of ERK1/2 and MEK1/2 in serum-deprived astrocytes. In cerebellar granule cells millimolar lithium enhanced ERK and MEK phosphorylation. We propose that he opposing effects of lithium in neurons and astrocytes make lithium treatment a promising strategy to favour neuronal repair and reduce reactive gliosis after traumatic injury.
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Lye, Mark A. [Verfasser]. "Der gutgläubige Erwerb der streitbefangenen Sache / Mark A. Lye." Frankfurt a.M. : Peter Lang GmbH, Internationaler Verlag der Wissenschaften, 2016. http://d-nb.info/1122004079/34.

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Psarras, Alkiviadis C. "Trade mark licensing in England and Greece : a comparative approach." Thesis, University of Kent, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358920.

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Hays, Thomas Edward. "The parallel importation of trade mark protected goods under European Union law." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619934.

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Books on the topic "Mrk 348"

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Zeichner, Walter. Jaguar Mark II and 240/340/S-type/Daimler V8 plus Mark VII/VIII/IX, 1955-69: A documentation. West Chester, Pa: Schiffer Pub., 1989.

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Messent, Peter. Mark Twain. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8.

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Newbold, David. Destination Ca’ Foscari. Venice: Edizioni Ca' Foscari, 2019. http://dx.doi.org/10.30687/978-88-6969-360-1.

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This is a sequel to the volume My Mobility, published as part of the celebrations to mark the 150th anniversary of Ca’ Foscari University of Venice. It contains 38 accounts by students from 21 different countries, who write about their experience in Venice and at Ca’ Foscari. As well as being a celebration of the mobility experience itself, it testifies to the huge importance of international exchanges between universities, and how they can contribute to the promotion of tolerance, friendship, and mutual understanding.
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The cry of Jesus on the cross: A biblical and theological study. New York: Paulist Press, 1987.

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Watts, John D. W., Robert A. Guelich, David Allen Hubbard, Ralph P. Martin, and Glenn W. Barker. Mark 1-8: 26, Volume 34A. Zondervan, 2015.

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Watts, John D. W., Robert A. Guelich, David Allen Hubbard, Ralph P. Martin, and Glenn W. Barker. Mark 1-8: 26, Volume 34A. Zondervan, 2018.

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Watts, John D. W., Craig A. Evans, David Allen Hubbard, Glenn W. Barker, and Bruce M. Metzger. Mark 8 : 27-16: 20, Volume 34B. Zondervan, 2015.

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Watts, John D. W., Craig A. Evans, David Allen Hubbard, Glenn W. Barker, and Bruce M. Metzger. Mark 8 : 27-16: 20, Volume 34B. Zondervan, 2018.

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(Editor), Ralph P. Martin, and Lynn A. Losie (Editor), eds. Word Biblical Commentary Vol. 34b, Mark 8:27-16:20 (evans). Thomas Nelson, 2001.

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Guelich, Robert A. Word Biblical Commentary Vol. 34a, Mark 1-8:26 (guelich), 498pp. Thomas Nelson, 1989.

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Book chapters on the topic "Mrk 348"

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Peck, A. B., C. Henkel, and J. S. Ulvestad. "A Masing Molecular Cloud in the Central Parsecs of Mrk 348." In Springer Proceedings in Physics, 169–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-18902-9_30.

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Flick, Herman. "MRI-spoelen." In Magnetic Resonance Imaging, 155–64. Houten: Bohn Stafleu van Loghum, 2017. http://dx.doi.org/10.1007/978-90-368-1934-3_10.

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Messent, Peter. "Keeping Both Eyes Open: ‘The Stolen White Elephant’." In Mark Twain, 1–21. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_1.

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Messent, Peter. "Old World Travel: The Innocents Abroad." In Mark Twain, 22–43. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_2.

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Messent, Peter. "Roughing It and the American West." In Mark Twain, 44–64. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_3.

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Messent, Peter. "Tom Sawyer and American Cultural Life: Anxieties and Accommodations." In Mark Twain, 65–85. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_4.

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Messent, Peter. "Racial Politics in Huckleberry Finn." In Mark Twain, 86–109. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_5.

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Messent, Peter. "Fantasy and A Connecticut Yankee in King Arthur’s Court." In Mark Twain, 110–33. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_6.

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Messent, Peter. "Severed Connections: Puddn’head Wilson and Those Extraordinary Twins." In Mark Twain, 134–56. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_7.

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Messent, Peter. "The Late Works: Incompletion, Instability, Contradiction." In Mark Twain, 157–76. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-25271-8_8.

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Conference papers on the topic "Mrk 348"

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Doi, Akihiro, Seiji Kameno, Satoko Sawada-Satoh, K. Hada, and Takafumi Haga. "Water vapor megamasers in a circumnuclear ionized torus in the Seyfert galaxy Mrk 348." In 11th European VLBI Network Symposium & Users Meeting. Trieste, Italy: Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.178.0085.

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Kansa, E. J. "Radial basis functions: achievements and challenges." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380011.

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Godinho, L., D. Soares, and P. G. Santos. "An ACA-MFS approach for the analysis of sound propagation in sonic crystals." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380021.

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Degtiariov, K., V. Gnitko, V. Naumenko, and E. Strelnikova. "BEM in free vibration analysis of elastic shells coupled with liquid sloshing." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380031.

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Peixoto, H. de Farias Costa, L. Simões Novelino, and N. A. Dumont. "Basics of a fast-multipole unified technique for the analysis of several classes of continuum mechanics problems with the boundary element method." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380041.

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Mužík, J., and K. Kovářík. "A characteristic-based split meshless local Petrov–Galerkin method for unsteady three-dimensional incompressible fluid flow." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380051.

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Stevens, D., and H. Power. "A local RBF method based on a finite collocation approach." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380061.

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Chen, J. T., W. S. Huang, Y. T. Lee, and S. K. Kao. "A necessary and sufficient BEM/BIEM for two-dimensional elasticity problems." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380071.

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Jing, G., H. Isakari, T. Matsumoto, T. Yamada, and T. Takahashi. "Topology optimisation for heat conduction problems in 2D with heat transfer boundary condition and heat flux objective function defined on morphing boundaries using BEM." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380081.

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Xu, Y. M., H. B. Chen, and L. L. Chen. "FEM/FMBEM coupling for acoustic structure interaction and acoustic design sensitivity analysis with sound-absorbing materials." In BEM/MRM 38. Southampton, UK: WIT Press, 2015. http://dx.doi.org/10.2495/bem380091.

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Reports on the topic "Mrk 348"

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Wu, Eric C. Performance Oriented Packaging Testing of Container, Shipping and Storage, Mk 34 Mod 0. Fort Belvoir, VA: Defense Technical Information Center, May 1991. http://dx.doi.org/10.21236/ada236013.

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