Symmetry, quasisymmetry, and critical phenomena

2007 ◽  
Vol 85 (6) ◽  
pp. 653-662
Author(s):  
D J Rowe
Keyword(s):  
Group Theory ◽  
Symmetry Breaking ◽  
Critical Phenomena ◽  
Quantum Phase Transitions ◽  
Fundamental Interest ◽  
The Face ◽  
Rapid Transition ◽  
21.60 Ev ◽  
New Phase

This presentation is an analysis of the role of symmetry in second-order quantum phase transitions. It seeks to explain why transitions between phases of systems, associated with different symmetries, exhibit critical phenomena. It transpires that a system in one phase, tends to hold onto the symmetry associated with that phase until a breaking point is reached at which a rapid transition occurs to a new phase associated with a different symmetry. Understanding what is happening presents the challenge of explaining how a system "holds on" to a symmetry in the face of strong symmetry-breaking interactions. The explanation is of fundamental interest in physics, for understanding why models with built in symmetries often work extremely well even when the models ignore large symmetry-breaking interactions that are known to be present. When this phenomenon occurs, we say that the system has a quasidynamical symmetry. This concept is of interest in mathematics because it turns out that quasidyndamical symmetries are the physical realizations of a new concept in group theory, which we refer to as an embedded representation. PACS Nos.: 21.60.Fw, 21.60.Ev, 64.6–.Ht, 68.18.Jk

Phase Transitions, Critical Phenomena, and Finite-Size Scaling

2019 ◽  
pp. 111-176
Author(s):  
Hans-Peter Eckle
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Phenomena ◽  
Quantum Phase Transitions ◽  
Finite Size ◽  
System Size ◽  
Thermal Fluctuations ◽  
Finite Size Scaling ◽  
Size Scaling

Interacting many-particle systems may undergo phase transitions and exhibit critical phenomena in the limit of infinite system size, while the precursors of these phenomena are studied in the theory of finite-size scaling. After surveying the basic notions of phases, phase diagrams, and phase transitions, this chapter focuses on critical behaviour at a second-order phase transition. The Landau-Ginzburg theory and the concept of scaling prepare readers for an elementary introduction to the concepts of the renormalization group, followed by an introduction into the field of quantum phase transitions where quantum fluctuations take over the role of thermal fluctuations.

Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

2020 ◽  
Vol 48 (3) ◽  
pp. 1243-1253 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Cell Cortex ◽  
Axis Formation ◽  
Aurora A Kinase ◽  
Aurora A ◽  
C Elegans ◽  
Cell Embryo ◽  
Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

Questions on the role of biofilms for the adaptation of microorganisms to unfavorable environmental factors by the example of P. aeruginosa

2020 ◽  
Vol 99 (4) ◽  
pp. 379-383
Author(s):  
Vasily N. Afonyushkin ◽  
N. A. Donchenko ◽  
Ju. N. Kozlova ◽  
N. A. Davidova ◽  
V. Yu. Koptev ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Barrier Function ◽  
Infectious Agent ◽  
Antagonistic Activity ◽  
The Body ◽  
Main Function ◽  
Pathogenic Potential ◽  
The Face

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

The Modern Aristotle: Michael Polanyi’s Search for Truth against Nihilism

2018 ◽  
Author(s):  
Ronald Hoinski ◽  
Ronald Polansky
Keyword(s):  
Philosophy Of Science ◽  
Modern Science ◽  
Michael Polanyi ◽  
Contemporary Philosophy ◽  
The Face ◽  
Human Desire ◽  
The Mind ◽  
Theoretical Science

David Hoinski and Ronald Polansky’s “The Modern Aristotle: Michael Polanyi’s Search for Truth against Nihilism” shows how the general tendencies of contemporary philosophy of science disclose a return to the Aristotelian emphasis on both the formation of dispositions to know and the role of the mind in theoretical science. Focusing on a comparison of Michael Polanyi and Aristotle, Hoinski and Polansky investigate to what degree Aristotelian thought retains its purchase on reality in the face of the changes wrought by modern science. Polanyi’s approach relies on several Aristotelian assumptions, including the naturalness of the human desire to know, the institutional and personal basis for the accumulation of knowledge, and the endorsement of realism against objectivism. Hoinski and Polansky emphasize the promise of Polanyi’s neo-Aristotelian framework, which argues that science is won through reflection on reality.

Making a Right Tit of Myself: Subverting the Trajectory of Mastectomy: Soma, Psyche, Techné

Somatechnics ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 9-30
Author(s):  
Fiona K. O'Neill
Keyword(s):  
Breast Cancer ◽  
Cancer Survivors ◽  
Breast Cancer Survivors ◽  
Personal Narrative ◽  
Abrupt Transition ◽  
The Face ◽  
Rapid Transition ◽  
Return Journey ◽  
The Uk

In the UK, when one is suspected of having breast cancer there is usually a rapid transition from being diagnosed, to being told you require treatment, to this being effected. Hence, there is a sense of an abrupt transition from ‘normal’ embodiment through somatechnic engagement; from normality, to failure and otherness. The return journey to ‘embodied normality’, if indeed there can be one, is the focus of this paper; specifically the durée and trajectory of such normalisation. I offer a personal narrative from encountering these ‘normalising interventions’, supported by the narratives of other ‘breast cancer survivors’. Indeed, I havechosento become acquainted with my altered/novel embodiment, rather than the symmetrisation of prosthetication, to ‘wear my scars’,and thus subvert the trajectory of mastectomy. I broach and brook various encounters with failure by having, being and doing a body otherwise; exploring, mastering and re-capacitating my embodiment, finding the virtuosity of failure and subversion. To challenge the durée of ‘normalisation’ I have engaged in somatic movement practices which allow actual capacities of embodiment to be realised; thorough kinaesthetic praxis and expression. This paper asks is it soma, psyche or techné that has failed me, or have I failed them? What mimetic chimera ‘should’ I become? What choices do we have in the face of failure? What subversions can be allowed? How subtle must one be? What referent shall I choose? What might one assimilate? Will mimesis get me in the end? What capacities can one find? How shall I belong? Where / wear is my fidelity? The hope here is to address the intra-personal phenomenological character and the inter-corporeal socio-ethico-political aspects that this body of failure engenders, as one amongst many.

Expansion of borders in the Kurdistan region and local and regional positions

2019 ◽  
Vol 3 (11) ◽  
pp. 1
Author(s):  
Harith Qahtan Abdullah ◽  
Abbas Fadel Atwan
Keyword(s):  
Middle East ◽  
Central Government ◽  
Kurdistan Region ◽  
War On Terrorism ◽  
National State ◽  
The Face ◽  
In The Beginning

The borders of Kurdistan represent an important point in Kurdish thought. They represent the hope of establishing their national state. The circumstances of the war on terrorism in Iraq and Syria have led to the emergence of what is known as a "propaganda" and the formation of a global front in its struggle. And with the signs of the collapse of the Syrian state and the weakness of the Iraqi state in the face of the "dashing" in the beginning. These circumstances led to the emergence of the role of the Kurdistan region in the confrontation "ISIS" and maintain the administrative border in the three provinces of Kurdistan in addition to the province of Kirkuk. That the circumstances of the war on terrorism created new international conditions on the Middle East arena, which will generate many problems between the Kurdistan region and the central government of Baghdad, as well as other problems between the region, Syria, Turkey and Iran. The war on terrorism has made countries free to fight the opposition groups under the name Terrorism by their classification. The Turkish side is fighting the PKK within the borders of the Kurdistan region, and this war can develop in a post-"warlike" phase. The war in Syria is also contradictory to vision and not resolved to a specific side and Iran's position on developments is encouraging.

FAITH–BASED COMMUNITIES AND POLITICS IN DULLSTROOM-EMNOTWENI: LOCAL STORIES OF IDENTITY

2016 ◽  
Vol 1 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Christina Landman
Keyword(s):  
Higher Education ◽  
Service Delivery ◽  
Special Focus ◽  
Traditional Role ◽  
Cultural Conflicts ◽  
Local Identities ◽  
Political Interests ◽  
Local Municipality ◽  
The Face

A majority of the black community of Dullstroom-Emnotweni in the Mpumalanga highveld in the east of South Africa trace their descent back to the southern Ndebele of the so-called ‘Mapoch Gronden’, who lost their land in the 1880s to become farm workers on their own land. A hundred years later, in 1980, descendants of the ‘Mapoggers’ settled in the newly built ‘township’ of Dullstroom, called Sakhelwe, finding jobs on the railways or as domestic workers. Oral interviews with the inhabitants of Sakhelwe – a name eventually abandoned in favour of Dullstroom- Emnotweni – testify to histories of transition from landowner to farmworker to unskilled labourer. The stories also highlight cultural conflicts between people of Ndebele, Pedi and Swazi descent and the influence of decades of subordination on local identities. Research projects conducted in this and the wider area of the eMakhazeni Local Municipality reveal the struggle to maintain religious, gender and youth identities in the face of competing political interests. Service delivery, higher education, space for women and the role of faith-based organisations in particular seem to be sites of contestation. Churches and their role in development and transformation, where they compete with political parties and state institutions, are the special focus of this study. They attempt to remain free from party politics, but are nevertheless co-opted into contra-culturing the lack of service delivery, poor standards of higher education and inadequate space for women, which are outside their traditional role of sustaining an oppressed community.

The Prophetic Voice of the Church in a Democratic South Africa – A Theological Reflection

2018 ◽  
Vol 15 (2) ◽  
Author(s):  
Lufuluvhi Maria Mudimeli
Keyword(s):  
South Africa ◽  
Economic Transformation ◽  
The State ◽  
Black Liberation ◽  
South Africans ◽  
Black Liberation Theology ◽  
Prophetic Voice ◽  
The Face ◽  
The Church

This article is a reflection on the role and contribution of the church in a democratic South Africa. The involvement of the church in the struggle against apartheid is revisited briefly. The church has played a pivotal and prominent role in bringing about democracy by being a prophetic voice that could not be silenced even in the face of death. It is in this time of democracy when real transformation is needed to take its course in a realistic way, where the presence of the church has probably been latent and where it has assumed an observer status. A look is taken at the dilemmas facing the church. The church should not be bound and taken captive by any form of loyalty to any political organisation at the expense of the poor and the voiceless. A need for cooperation and partnership between the church and the state is crucial at this time. This paper strives to address the role of the church as a prophetic voice in a democratic South Africa. Radical economic transformation, inequality, corruption, and moral decadence—all these challenges hold the potential to thwart our young democracy and its ideals. Black liberation theology concepts are employed to explore how the church can become prophetically relevant in democracy. Suggestions are made about how the church and the state can best form partnerships. In avoiding taking only a critical stance, the church could fulfil its mandate “in season and out of season” and continue to be a prophetic voice on behalf of ordinary South Africans.

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