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S. Reveliotis - One of the best experts on this subject based on the ideXlab platform.

  • A Necessary and Sufficient Condition for the Liveness and Reversibility of Process-Resource Nets With Acyclic, Quasi-live, Serializable, and Reversible Process Subnets
    IEEE Transactions on Automation Science and Engineering, 2006
    Co-Authors: S. Reveliotis
    Abstract:

    The first part of this paper develops a linear characterization for the space of the Petri net markings that are reachable from the initial marking M0 through bounded-length fireable transition sequences. The second part discusses the practical implications of this result for the liveness and reversibility analysis of a particular class of Petri nets known as Process-resource nets with acyclic, quasi-live, serializable, and Reversible Process subnets. Note to Practitioners-One of the main challenges in the analysis and design of the resource allocation taking place in modern technological systems is the verification of certain properties of the system behavior such as liveness and deadlock freedom. The last decade has seen the development of a number of computational tests that can evaluate the aforementioned properties for a large class of resource allocation systems. The tests that are most promising essentially verify the target properties by establishing the absence of some undesirable structure from the states that are reachable during system operation. As a result, the effective execution of these tests necessitates the effective representation of the underlying reachability space. Yet, in the past, the development of a concise and computationally manageable representation of the system reachability space has been considered to be a challenging proposition and a factor that compromises the resolution power of the aforementioned tests. The work presented in this paper establishes that for a very large class of the considered resource allocation systems, the underlying reachability space admits a precise and computationally efficient characterization, which subsequently leads to more powerful verification tools of the target behavioral properties

  • A linear characterization of the Petri net reachability space corresponding to bounded-length fireable transition sequences and its implications for the structural analysis of Process-resource nets with acyclic, quasi-live and strongly Reversible pro
    Proceedings of the 44th IEEE Conference on Decision and Control, 2005
    Co-Authors: S. Reveliotis
    Abstract:

    The first part of this paper develops a linear characterization for the space of the Petri net markings that are reachable from the initial marking, M0, through bounded-length fireable transition sequences. The second part discusses the practical implications of this result for the liveness and reversibility analysis of a particular class of Petri nets known as Process-resource nets with acyclic, quasi-live and strongly Reversible Process subnets.

Michael Karin - One of the best experts on this subject based on the ideXlab platform.

  • Immunity by ubiquitylation: a Reversible Process of modification
    Nature Reviews Immunology, 2005
    Co-Authors: Josef M. Penninger, Michael Karin
    Abstract:

    The conjugation of ubiquitin, a 76-amino-acid peptide, to a protein substrate provides a tag that either marks the labelled protein for degradation or modulates its function. The Process of protein ubiquitylation — which is catalysed by coordinated enzymatic reactions that are mediated by enzymes known as E1, E2 and E3 — has an important role in the modulation of immune responses. Importantly, protein ubiquitylation is a Reversible Process, and removal of ubiquitin molecules is mediated by de-ubiquitylating enzymes: for example, A20, which has been implicated in the regulation of immune responses. In addition, the conjugation of ubiquitin-like molecules, such as ISG15 (interferon-stimulated protein of 15 kDa), to proteins is also involved in immune regulation. This Review covers recent progress in our understanding of protein ubiquitylation in the immune system. Conjugation of ubiquitin to a protein substrate provides a tag that either marks the labelled protein for degradation or modulates its function. The Process of ubiquitylation, which is catalysed by coordinated enzymatic reactions that require enzymes known as E1, E2 and E3, has an important role in the modulation of immune responses. Immune tolerance is induced in the thymus and the periphery through diverse mechanisms, and E3 ligases are involved in thymic antigen presentation, T-cell anergy and follicular B helper T-cell development. The immunological defect in mice with a disrupted itchy ( Itch ) locus results from a defect in degradation of the transcription factor JUNB. This Process is tightly regulated by upstream protein kinases that modulate the activity of the E3 ligase ITCH rather than directly affect JUNB, as commonly thought. Nuclear factor-κB (NF-κB) signalling is crucial for both innate and adaptive immunity and is regulated by K48 (Lys48)-linked polyubiquitylation (which targets inhibitor of NF-κB (IκB) for proteasomal-dependent degradation), K63-linked polyubiquitylation (which activates IκB kinase, IKK) and A20-mediated de-ubiquitylation. E3 ligases also regulate other cytokine-induced cellular responses, such as transforming-growth-factor-β-mediated signalling and interferon (IFN)-triggered gene expression. The ubiquitin-like molecule ISG15 (IFN-stimulated protein of 15 kDa) participates in IFN-mediated signalling, and defects in de-ISGylation result in resistance to viral infection.

  • Immunity by ubiquitylation: a Reversible Process of modification
    Nature reviews. Immunology, 2005
    Co-Authors: Yun Cai Liu, Josef M. Penninger, Michael Karin
    Abstract:

    The conjugation of ubiquitin, a 76-amino-acid peptide, to a protein substrate provides a tag that either marks the labelled protein for degradation or modulates its function. The Process of protein ubiquitylation--which is catalysed by coordinated enzymatic reactions that are mediated by enzymes known as E1, E2 and E3--has an important role in the modulation of immune responses. Importantly, protein ubiquitylation is a Reversible Process, and removal of ubiquitin molecules is mediated by de-ubiquitylating enzymes: for example, A20, which has been implicated in the regulation of immune responses. In addition, the conjugation of ubiquitin-like molecules, such as ISG15 (interferon-stimulated protein of 15 kDa), to proteins is also involved in immune regulation. This Review covers recent progress in our understanding of protein ubiquitylation in the immune system.

Lgj Frenken - One of the best experts on this subject based on the ideXlab platform.

  • thermal unfolding of a llama antibody fragment a two state Reversible Process
    Biochemistry, 2001
    Co-Authors: Jmj Perez, J G Renisio, Jeanine J Prompers, C J Van Platerink, Christian Cambillau, Herve Darbon, Lgj Frenken
    Abstract:

    Camelids produce functional "heavy chain" antibodies which are devoid of light chains and CH1 domains [Hamers-Casterman, C., et al. (1993) Nature 363, 446-448]. It has been shown that the variable domains of these heavy chain antibodies (the V(HH) fragments) are functional at or after exposure to high temperatures, in contrast to conventional antibodies [Linden van der, R. H. J., et al. (1999) Biochim. Biophys. Acta 1431, 37-44]. For a detailed understanding of the higher thermostability of these V(HH) fragments, knowledge of their structure and conformational dynamics is required. As a first step toward this goal, we report here the essentially complete (1)H and (15)N NMR backbone resonance assignments of a llama V(HH) antibody fragment, and an extensive analysis of the structure at higher temperatures. The H-D exchange NMR data at 300 K indicate that the framework of the llama V(HH) fragment is highly protected with a DeltaG(ex) of >5.4 kcal/mol, while more flexibility is observed for surface residues, particularly in the loops and the two outer strands (residues 4-7, 10-13, and 58-60) of the beta-sheet. The CD data indicate a Reversible, two-state unfolding mechanism with a melting transition at 333 K and a DeltaH(m) of 56 kcal/mol. H-D exchange studies using NMR and ESI-MS show that below 313 K exchange occurs through local unfolding events whereas above 333 K exchange mainly occurs through global unfolding. The lack of a stable core at high temperatures, observed for V(HH) fragments, has also been observed for conventional antibody fragments. The main distinction between the llama V(HH) fragment and conventional antibody fragments is the reversibility of the thermal unfolding Process, explaining its retained functionality after exposure to high temperatures.

Steven Baldelli - One of the best experts on this subject based on the ideXlab platform.

  • Influence of water on the surface of hydrophilic and hydrophobic room-temperature ionic liquids
    Journal of the American Chemical Society, 2004
    Co-Authors: Selimar Rivera-rubero, Steven Baldelli
    Abstract:

    Vibrational spectroscopy, sum frequency generation, has been used to study the gas-liquid interface of imidazolium-based, room-temperature ionic liquids. The ionic liquids are divided into two categories on the basis of their miscibility with water, as hydrophobic (immiscible) and hydrophilic (miscible). The spectroscopy results indicate that water will reorient the cations of the hydrophobic ionic liquid, while in the hydrophilic ones they remain unaffected. Thus, under low water conditions the plane of the imidazolium ring remains parallel to the surface for both types of ionic liquid. However, at high water content the ring will reorient to along the surface normal for the hydrophobic ionic liquid but remain parallel to the surface for the hydrophilic one. This is a Reversible Process.

Hua Bao - One of the best experts on this subject based on the ideXlab platform.

  • conjugated silicon based polymer resists for nanotechnologies eb and uv meditated degradation Processes in polysilanes
    Materials Transactions, 2010
    Co-Authors: František Schauer, Petr Schauer, Ivo Ku V R Itka, Hua Bao
    Abstract:

    The comparison of the susceptibility of aryl-substituted polysilanes to the photodegradation by electron beam (EB) and UV radiation is examined on the prototypical material, poly[methyl(phenyl)silylene] (PMPSi). The main purpose of this paper is to compare the photoluminescence (PL) and cathodoluminescence (CL) after major degradation, predominantly in the long wavelength range of 400–600 nm, studying the disorder due to dangling bonds, conformational transformations and weak bonds created by the degradation Process. The UV degradation was a completely Reversible Process, whereas the EB degradation Process was only Reversible, provided certain material specific level of degradation was not exceeded. This observation supports different paths and final states in both UV and EB degradations. The results serve for the optimization of polysilane nanoresists. [doi:10.2320/matertrans.MC200925]

  • Conjugated Silicon–Based Polymer Resists for Nanotechnologies: EB and UV Meditated Degradation Processes in Polysilanes
    2009
    Co-Authors: František Schauer, Petr Schauer, Hua Bao
    Abstract:

    The comparison of the susceptibility of aryl-substituted polysilanes to the photodegradation by electron beam (EB) and UV radiation is examined on the prototypical material, poly[methyl(phenyl)silylene] (PMPSi). The main purpose of this paper is to compare the photoluminescence (PL) and cathodoluminescence (CL) after major degradation, predominantly in the long wavelength range of 400–600 nm, studying the disorder due to dangling bonds, conformational transformations and weak bonds created by the degradation Process. The UV degradation was a completely Reversible Process, whereas the EB degradation Process was only Reversible, provided certain material specific level of degradation was not exceeded. This observation supports different paths and final states in both UV and EB degradations. The results serve for the optimization of polysilane nanoresists. [doi:10.2320/matertrans.MC200925