scholarly journals Symmetry structure in discrete models of biochemical systems: natural subsystems and the weak control hierarchy in a new model of computation driven by interactions

2015 ◽  
Vol 373 (2046) ◽  
pp. 20140223 ◽  
Author(s):  
Chrystopher L. Nehaniv ◽  
John Rhodes ◽  
Attila Egri-Nagy ◽  
Paolo Dini ◽  
Eric Rothstein Morris ◽  
...  
Keyword(s):  
Systems Biology ◽  
Genetic Regulation ◽  
Krebs Cycle ◽  
Internal Symmetry ◽  
Discrete Models ◽  
Lac Operon ◽  
New Model ◽  
Model Of Computation ◽  
Natural Systems ◽  
Wide Range

Interaction computing is inspired by the observation that cell metabolic/regulatory systems construct order dynamically, through constrained interactions between their components and based on a wide range of possible inputs and environmental conditions. The goals of this work are to (i) identify and understand mathematically the natural subsystems and hierarchical relations in natural systems enabling this and (ii) use the resulting insights to define a new model of computation based on interactions that is useful for both biology and computation. The dynamical characteristics of the cellular pathways studied in systems biology relate, mathematically, to the computational characteristics of automata derived from them, and their internal symmetry structures to computational power. Finite discrete automata models of biological systems such as the lac operon, the Krebs cycle and p53–mdm2 genetic regulation constructed from systems biology models have canonically associated algebraic structures (their transformation semigroups). These contain permutation groups (local substructures exhibiting symmetry) that correspond to ‘pools of reversibility’. These natural subsystems are related to one another in a hierarchical manner by the notion of ‘ weak control ’. We present natural subsystems arising from several biological examples and their weak control hierarchies in detail. Finite simple non-Abelian groups are found in biological examples and can be harnessed to realize finitary universal computation . This allows ensembles of cells to achieve any desired finitary computational transformation, depending on external inputs, via suitably constrained interactions. Based on this, interaction machines that grow and change their structure recursively are introduced and applied, providing a natural model of computation driven by interactions.

Dynamic Random-Access Stored-Program Machine for Runtime Code Modification

2015 ◽  
Vol 26 (04) ◽  
pp. 441-463
Author(s):  
Jarosław Rudy
Keyword(s):  
Programming Languages ◽  
Random Access ◽  
Time And Space ◽  
Models Of Computation ◽  
New Model ◽  
Model Of Computation ◽  
Wide Range ◽  
Empirical Tests ◽  
Theoretical Results ◽  
Code Modification

This paper is concerned with the study of possibility of performing changes to existing running programs with the use of the RAM and RASP models of computation. A new model of computation is defined with the capability of performing runtime changes. Theoretical properties, including time and space complexities, of the defined models are presented and proven. A number of simple empirical tests are conducted in order to prove the ability to perform runtime changes as well as support obtained theoretical results. The paper concludes that the defined model has virtually no affect on performance when there are no changes and the performance with changes is easily manageable. Moreover, the results can be used to develop runtime change capabilities for a wide range of programming languages and paradigms.

scholarly journals Chromosomal Locus That Affects Pathogenicity of Rhodococcus fascians

2002 ◽  
Vol 184 (4) ◽  
pp. 1112-1120 ◽  
Author(s):  
Danny Vereecke ◽  
Karen Cornelis ◽  
Wim Temmerman ◽  
Mondher Jaziri ◽  
Marc Van Montagu ◽  
...  
Keyword(s):  
Krebs Cycle ◽  
Malate Synthase ◽  
Habitat Modification ◽  
Signal Molecules ◽  
In Planta ◽  
Chromosomal Locus ◽  
Physiological Alterations ◽  
Rhodococcus Fascians ◽  
Wide Range ◽  
Symptomatic Tissue

ABSTRACT The gram-positive plant pathogen Rhodococcus fascians provokes leafy gall formation on a wide range of plants through secretion of signal molecules that interfere with the hormone balance of the host. Crucial virulence genes are located on a linear plasmid, and their expression is tightly controlled. A mutant with a mutation in a chromosomal locus that affected virulence was isolated. The mutation was located in gene vicA, which encodes a malate synthase and is functional in the glyoxylate shunt of the Krebs cycle. VicA is required for efficient in planta growth in symptomatic, but not in normal, plant tissue, indicating that the metabolic requirement of the bacteria or the nutritional environment in plants or both change during the interaction. We propose that induced hyperplasia on plants represents specific niches for the causative organisms as a result of physiological alterations in the symptomatic tissue. Hence, such interaction could be referred to as metabolic habitat modification.

scholarly journals Enhancing the resilience of coupled human and natural systems of alpine rangelands on the Qinghai-Tibetan Plateau

2015 ◽  
Vol 37 (1) ◽  
pp. i ◽  
Author(s):  
Shikui Dong ◽  
Ruth Sherman
Keyword(s):  
Tibetan Plateau ◽  
Science Policy ◽  
Sustainable Management ◽  
Environmental Changes ◽  
Policy Design ◽  
Rangeland Management ◽  
Special Issue ◽  
Natural Systems ◽  
Wide Range ◽  
Science Policy Interface

This special issue covers a wide range of topics on the protection and sustainable management of alpine rangelands on the Qinghai-Tibetan Plateau (QTP), including Indigenous knowledge of sustainable rangeland management, science-policy interface for alpine rangeland biodiversity conservation, adaptations of local people to social and environmental changes and policy design for managing coupled human-natural systems of alpine rangelands.

scholarly journals Professional characteristics of an educator: A survey of literature

2013 ◽  
Vol 25 (1) ◽  
pp. 1-22
Author(s):  
J. Anitha ◽  
R. Krishnaveni
Keyword(s):  
Student Outcome ◽  
Wide Scope ◽  
Review Of Literature ◽  
New Model ◽  
Professional Characteristics ◽  
Wide Range ◽  
Made In ◽  
Comprehensive Study

Literature has shown that various studies have dealt with different professional features of teaching and they have focused on one or few professional characteristics of educators. In spite of the immense amount of literature on educator characteristics, a comprehensive study that would encompass the vital professional characteristics of an educator in total is lacking. This has instigated the researcher to take up the study to identify the professional characteristics of an educator. An attempt was made in identifying the educators' characteristics using student outcome as a boundary criterion to select the characteristics from among several that are available in the literature. Therefore, a new model of professional characteristics of educators was proposed. This paper discusses in detail, the characteristics of a profession in general and the wide range of educator’s characteristics as studied in previous researches. The paper presents a wide scope for the models developed to be studied in depth to appreciate and investigate more about the professional characteristics identified through this review of literature. The models may also be tested empirically for further accumulation of knowledge in the field.

scholarly journals Endopeptidase PepO Regulates the SpeB Cysteine Protease and Is Essential for the Virulence of Invasive M1T1Streptococcus pyogenes

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Stephan Brouwer ◽  
Amanda J. Cork ◽  
Cheryl-Lynn Y. Ong ◽  
Timothy C. Barnett ◽  
Nicholas P. West ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Phase ◽  
Cysteine Protease ◽  
Genetic Regulation ◽  
Bacterial Pathogen ◽  
Targeted Mutagenesis ◽  
Human Neutrophils ◽  
Content Type ◽  
Wide Range ◽  
Human Infections

ABSTRACTStreptococcus pyogenes(group AStreptococcus[GAS]) causes a wide range of human infections. The pathogenesis of GAS infections is dependent on the temporal expression of numerous secreted and surface-associated virulence factors that interact with host proteins. Streptococcal pyrogenic exotoxin B (SpeB) is one of the most extensively studied toxins produced by GAS, and the coordinate growth phase-dependent regulation ofspeBexpression is linked to disease severity phenotypes. Here, we identified the endopeptidase PepO as a novel growth phase-dependent regulator of SpeB in the invasive GAS M1 serotype strain 5448. By using transcriptomics followed by quantitative reverse transcriptase PCR and Western blot analyses, we demonstrate through targeted mutagenesis that PepO influences growth phase-dependent induction ofspeBgene expression. Compared to wild-type and complemented mutant strains, we demonstrate that the 5448ΔpepOmutant strain is more susceptible to killing by human neutrophils and is attenuated in virulence in a murine model of invasive GAS infection. Our results expand the complex regulatory network that is operating in GAS to control SpeB production and suggest that PepO is a virulence requirement during GAS M1T1 strain 5448 infections.IMPORTANCEDespite the continuing susceptibility ofS. pyogenesto penicillin, this bacterial pathogen remains a leading infectious cause of global morbidity and mortality. A particular subclone of the M1 serotype (M1T1) has persisted globally for decades as the most frequently isolated serotype from patients with invasive and noninvasive diseases in Western countries. One of the key GAS pathogenicity factors is the potent broad-spectrum cysteine protease SpeB. Although there has been extensive research interest on the regulatory mechanisms that controlspeBgene expression, its genetic regulation is not fully understood. Here, we identify the endopeptidase PepO as a new regulator ofspeBgene expression in the globally disseminated M1T1 clone and as being essential for virulence.

Part A: Articles: A Non-Governmental Human Rights Strategy for Peacekeeping?

1996 ◽  
Vol 14 (2) ◽  
pp. 127-145
Author(s):  
Reinhard Marx
Keyword(s):  
Human Rights ◽  
Moral Dilemma ◽  
International Community ◽  
Human Rights Violations ◽  
Neutral Position ◽  
New Model ◽  
Wide Range ◽  
Human Rights Movement ◽  
Protection Of Human Rights ◽  
Domestic Jurisdiction

The human rights movement has never accepted that human rights belong to the domestic jurisdiction, but the new model of peacekeeping, which to some extent is based on a human rights component, causes severe problems for the movement, particularly because of its selectivity and its often biased implementation. This obstacle to an impartial combat against massive human rights violations and a wide range of other problems make it difficult for the movement to develop a consistent and plausible policy on peacekeeping. Although the international community may have good reasons to deploy soldiers in order to save lives and to bring an end to genocide, a supportive attitude by the human rights movement may jeopardise its principles of impartiality and non-violent campaigning and hence weaken the system of protection of human rights. But it has to be underscored that massive human rights violations will cause a moral dilemma for the movement if it cannot justify its neutral position on compelling grounds.

Is the Asian house gecko, Hemidactylus frenatus, really a threat to Australia’s biodiversity?

2012 ◽  
Vol 60 (6) ◽  
pp. 361 ◽  
Author(s):  
E. P. Vanderduys ◽  
A. S. Kutt
Keyword(s):  
Current Evidence ◽  
Human Influence ◽  
Natural Habitats ◽  
Natural Systems ◽  
Wide Range ◽  
Hemidactylus Frenatus

Invasive animals can have a wide range of impacts in natural systems. The introduced Asian house gecko Hemidactylus frenatus has invaded widely in Australia, but is largely restricted to human-altered landscapes. Hoskin (2011) has argued that H. frenatus has the potential to negatively impact Australian ecosystems by invading natural habitats. We examine this contention by reviewing an extensive standardised fauna survey dataset collected in northern and central Queensland during the key period of H. frenatus expansion from the 1990s to 2012. In light of these data we also re-examine data from other areas that suggest H. frenatus is a benign threat and is unlikely to become an environmental pest within Australia. On current evidence, we conclude that H. frenatus is unlikely to spread much beyond areas of human influence.

Modified Nernst-Plank-Poisson Model for IPMC With Back-Relaxation Effects

2019 ◽  
Author(s):  
Aiman Al-Allaq ◽  
Nebojsa Jaksic ◽  
Bahaa Ansaf ◽  
Jude DePalma ◽  
Trung Duong
Keyword(s):  
Controller Design ◽  
Real Life ◽  
Poisson Model ◽  
Great Accuracy ◽  
Metal Composite ◽  
New Model ◽  
Relaxation Effects ◽  
Wide Range ◽  
Polymer Metal ◽  
Robotic Applications

Abstract The ionic polymer–metal composite (IPMC) is a new practical engineering material that, it has a wide range of capabilities in both dry and liquid environments. IPMC is a new candidate for diaphragms in micropump devices, micro and Nano robotic applications. IPMCs are regarded as a capable actuator for transportable applications, however, the unique combination of electrochemical and mechanical properties that they possess, such as back-relaxation, restraint their use in real-life applications. There have a lot of attempts to understand and model the IPMCs properties and build a whole prototype that can be used, with certainty, in different robotic, control, and medical applications, yet, till now, it seems that the dehydration and back-relaxation are still not modeled properly. The Nernst-Plank-Poisson was chosen to be the base model for the IPMC behavior, we were able to create a new model that truly represent the back-relaxation effects that occur in IPMCs, we’ve called the new model as modified NPP model. The modification used captured data from our experimental work Our modified analytical NPP (Nernst-Plank-Poisson) model was the verified using MATLAB & Simulink, which showed that the model, and the controller design for it was able to first compensate the loss of position of the IPMC due to back-relaxation, and then track the desired position input signals with great accuracy. The model and designed controller can be utilized in verity of robotic applications.

Multiphase Flow Performance Prediction Model for Twin-Screw Pump

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Peng Liu ◽  
Abhay Patil ◽  
Gerald Morrison
Keyword(s):  
Multiphase Flow ◽  
Operating Conditions ◽  
Model Verification ◽  
Leakage Flow ◽  
Screw Pump ◽  
New Model ◽  
Choked Flow ◽  
Screw Length ◽  
Wide Range ◽  
Twin Screw

This study is focused on the development and validation of an analytical model to predict the performance characteristics of multiphase flow twin-screw pump for wide range of operating conditions. A 200 HP, 635 gpm capacity multiphase flow twin-screw pump was tested with inlet pressure varying from 15 psig to 100 psig at gas void fraction (GVF) varying from 0% to 100% to validate the model. A new model is proposed to study the leakage flow in the twin screw pump. Adiabatic compressible flow is assumed in the circumferential clearance. The acceleration of the two-phase flow is taken into account in the new model. The change of Mach number of the leakage flow in the clearance and the possibility of choked flow at the outlet of the clearance was studied. Model provided important information about pressure distribution across the screw length, volumetric efficiency of the pump, and chocked flow condition. Model verification using experimental data concluded the paper.

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