11 research outputs found
Analysis of the quantum-classical Liouville equation in the mapping basis
No full textThe quantum-classical Liouville equation provides a description of the dynamics of a quantum subsystem coupled to a classical environment. Representing this equation in the mapping basis leads to a continuous description of discrete quantum states of the subsystem and may provide an alternate route to the construction of simulation schemes. In the mapping basis the quantum-classical Liouville equation consists of a Poisson bracket contribution and a more complex term. By transforming the evolution equation, term-by-term, back to the subsystem basis, the complex term (excess coupling term) is identified as being due to a fraction of the back reaction of the quantum subsystem on its environment. A simple approximation to quantum-classical Liouville dynamics in the mapping basis is obtained by retaining only the Poisson bracket contribution. This approximate mapping form of the quantum-classical Liouville equation can be simulated easily by Newtonian trajectories. We provide an analysis of the effects of neglecting the presence of the excess coupling term on the expectation values of various types of observables. Calculations are carried out on nonadiabatic population and quantum coherence dynamics for curve crossing models. For these observables, the effects of the excess coupling term enter indirectly in the computation and good estimates are obtained with the simplified propagation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3480018
A parallel MSF algorithm for planar graphs on a mesh and applications to image processing
No full textThe author presents an efficient O(n) parallel algorithm for finding a minimum-cost spanning forest (MSF) of a weighted undirected planar graph with n2 edges, on an nn mesh-connected computer. He also obtains efficient MSF-based O(n) algorithms for several application problems in image processing. In particular, he shows that an MSF can be used to obtain more efficient and elegant O(n) algorithms for the \u27k-width connectivity\u27 problem and the \u27optical clustering\u27 problem
A Study of Quantum-classical Dynamics in the Mapping Basis
No full textSolving quantum dynamics is an exponentially difficult problem. Thus, an exact numerical solution is inaccessible for any condensed matter system.
A promising approach is to divide the system into a quantum subsystem containing degrees of freedom which are of greater interest or those which have more profound quantum character (e.g., have smaller mass) and a classical bath containing the rest of the system.
Imposing such a partition and treating the bath classically results in quantum-classical dynamics. The quantum-classical Liouville equation is a general equation in the Hilbert space of quantum degrees of freedom while it resides in the phase space of the classical degrees of freedom.
Any numerical solution to this equation requires representation of the quantum subsystem in some basis. Solutions to this equation have been already proposed in the subsystem, adiabatic and force bases, each with its own cons and pros.
In this work, the quantum-classical equations of motion are cast in the subsystem basis and subsequently mapped to a number of fictitious harmonic oscillators.
The result is quantum-classical dynamics in the mapping basis which treats both quantum and classical degrees of freedom on the same footing, i.e., in phase space. Neglecting a portion of the back reaction of the quantum-subsystem to classical bath results in an expression for the time evolution of an operator (density matrix) equal to its Poisson bracket with the Hamiltonian.
This equation can be solved in terms of characteristics to provide a computationally tractable method for calculating quantum-classical dynamical properties. The expressions for expectation values and correlation functions in this formalism are derived.
Calculations on spin-boson system, barrier crossing models---the so called Tully models---and the Fenna-Mathews-Olson pigments show very good agreement between the results of this method and numerical solutions to the Schrödinger equation.Ph
A Study of Quantum-classical Dynamics in the Mapping Basis
No full textSolving quantum dynamics is an exponentially difficult problem. Thus, an exact numerical solution is inaccessible for any condensed matter system.
A promising approach is to divide the system into a quantum subsystem containing degrees of freedom which are of greater interest or those which have more profound quantum character (e.g., have smaller mass) and a classical bath containing the rest of the system.
Imposing such a partition and treating the bath classically results in quantum-classical dynamics. The quantum-classical Liouville equation is a general equation in the Hilbert space of quantum degrees of freedom while it resides in the phase space of the classical degrees of freedom.
Any numerical solution to this equation requires representation of the quantum subsystem in some basis. Solutions to this equation have been already proposed in the subsystem, adiabatic and force bases, each with its own cons and pros.
In this work, the quantum-classical equations of motion are cast in the subsystem basis and subsequently mapped to a number of fictitious harmonic oscillators.
The result is quantum-classical dynamics in the mapping basis which treats both quantum and classical degrees of freedom on the same footing, i.e., in phase space. Neglecting a portion of the back reaction of the quantum-subsystem to classical bath results in an expression for the time evolution of an operator (density matrix) equal to its Poisson bracket with the Hamiltonian.
This equation can be solved in terms of characteristics to provide a computationally tractable method for calculating quantum-classical dynamical properties. The expressions for expectation values and correlation functions in this formalism are derived.
Calculations on spin-boson system, barrier crossing models---the so called Tully models---and the Fenna-Mathews-Olson pigments show very good agreement between the results of this method and numerical solutions to the Schrödinger equation.Ph
A thematic comparative review of some English translations of the Qur'an
No full textThis thesis provides a thematic comparative review of some of the English translations of the Qur'an, including the works of Abdullah Yusuf Ali, Muhammad Asad, Taqiuddin Hilali and Muhsin Khan, and Zafarlshaq Ansari/Sayyid Mawdudi.
In this study, a new and unique approach is used to review and compare these translations along with their commentaries. They are reviewed based on the following four Qur'anic themes: Injunctions, Stories, Parables, and Short Chapters. These are some of the key themes where the Qur'an translations, especially the ones with commentary, often differ from each other and can be assessed objectively. For each theme, three to four examples are taken as samples from the Qur'an, and they are studied from different points of view. For example, the translation of the verses with injunctions will be reviewed for their relative emphasis over the letter versus the spirit of the law, consideration of jurisprudence knowledge, overall objectives of Islamic law, issues of this age, and impact of the translator's environment.
This approach is intended to identify further requirements for offering more accurate and more communicative translations of the Qur'an in the English language
Feminist Philosophical Toys : Playful Companions and Live Theorization
No full textWhat are the matters of philosophy? How do they shape how philosophy is practiced, what kinds of knowledge it produces, and who counts as a philosopher? The dominant matters of Western philosophy, or its epistemic companions, are books and journal articles even when dialogic and oral traditions are acknowledged or referenced. In this paper, we argue that alternatives would be necessary if philosophy were to be a more capacious and welcoming discipline. We introduce Feminist Philosophical Toys as one such alternative that challenges what counts as serious philosophy by being seriously playful. The toys foreground the oral and the dialogic while reflecting on and committing to engaging materiality, record-keeping, and record-making. In doing so, the toys challenge the dominant form of philosophy and its mechanics of knowledge-making as they offer an alternative way of doing philosophy that can be transformative for the next generation of feminist scholarship. The dialogic, embodied, and communal interaction with paper, with theory, and with others is meant as a practice of live theorization, opening philosophy to a new groundedness and accessibility, centered in the ethos of feminist epistemology, while at the same time pushing against fetishization of matter.CC BY-NC-ND 4.0 DEEDPublished online by Cambridge University Press: 30 April 2024Corresponding author: Nassim Parvin; Email: [email protected]</p
Spiritual condition devoted of Mevlâna: between "Enelhak" and «Khamush»
No full textUrl: http://sutad.selcuk.edu.tr/sutad/article/view/371Tasavvuf şiirinin en cesaretli şairi” (S.Nefisi) adlandırılan Mevlâna’nın şiirinin temel konuları insanın ruhunun yaratılıştan önceki hali, bu âleme gelişi ve yaşamının ali hedef ve maksatları, insanın ilahi hakikate ulaşmasının yol ve vesileleri, bu âlemle değil, geldiği ilahi âlemle ilgili telaşları gibi meselelerdir. Mevlâna’nın bu yöndeki düşüncesinde tezat teşkil eden iki kavram (“ene’l-hakk” ve “hamuş”) dikkatimizi çekti. Her iki İslamî kavram ruha mahsustur. Birinci ifade cismani varlıkla ilişkilerini kırarak “Hakta hak” olan ruhun, ikinci ise cisim dahilinde olduğundan dolayı hakikatlerin aslı hususunda susmaya mecbur kalan ruhun dilinden belirtiliyor. Mevlâna birinci kavrama “Fihi ma fih” ve “Masnevi”sinde hak kazandırsa da, ilahi ruha ait olarak değerlendirdiği “ene’l-hakk”a ortak çıkmıyor ve onu Hallac Mansur’un dilinden söylüyor. Oysa ilahi âlemle ilgili düşüncelerinin açıklık ve şath niteliğinde olmasına göre selef ve haleflerini çok geride bırakan Mevlâna, “Divan-ı Kebir”indeki şiirlerinin çoğunu “hamuş” ve onunla yakın anlamlı ifadelerle bildirir. Ünlü düşünürün bu görüşlerinin hareket noktası ise çoğu zaman “Biz hakikati söylemedik ki, toplumun nizamı bozulmasın” mülahazasıdır. Bu “hamuş”a her beytinde değişik ve yeni bir İslamî incelik katan Mevlâna bununla bazen ilahi hakikatin sırlarının “namahrem”den, “amm”dan gizli tutulması maksadını izliyor, bazen “hamuş”tan “zeban-e bizebani”ye geçidi kastediyor vs. Çünkü düşünüre göre, “hamuş”dan sonraki merhalede deha “harf”, “söz”, “dil” vs. ye ihtiyaç kalmıyor. Bundan sonraki hakikatler dilsiz dille (“lisan-e bilisani”) söylenir. Bazen ise o sadece “içinden gelen sesi dinlemek için susar” (M. Kaplan). Mevlâna’nın “hamuş” ifadesi ruhun “ağzı”, batini (ruha ait) duygu uzuvları hususundaki İslamî düşünceler, İslamî divan şiirinde çok rastlanan ağzın yok olarak tasavvuru ile yakından ilgilidir. Araştırmalarımızdan böyle bir sonuca vardık ki, “hamuş”, birtakım araştırmacının söylediği gibi, Mevlâna’nın mahlası olmayıp, “ehelhak” gibi onun İslamî görüşlerini ifade için ferdi ve özgün karakterli bir edebi-İslamî vasıta olarak kullanılmış, takipçilerinden Yunus Emre, Nesimi ve Fuzuli için de bir ilham kaynağı olmuştur.The basic themes of poetry of outstanding thinker Mevlâna, considered as one of the most courageous Sufi poets, are such as condition of soul before creation, the basic purposes of the arrival to this world and life, ways of achievement of divine true, confusion of the soul connected not with this world, but whence has arrived. In this direction our attention has involved two contrast concepts – “ene’l-hakk” and “khamush”. Both these Sufi concepts concern to condition of soul. The first concept is connected with the soul which broken off connections with a body and has become «true in true», and second one is connected with the soul, compelled to keep silence about essence of true because is found in the body. Despite of the justification of the first concept by Mevlâna in “Fihi ma fih” and “Mesnevi”, he does not share a place of divine soul, being a true source of “ene’l-hakk” and this expression is according to Hallage Mansur. Though Mevlâna had surpassed the predecessors and successors by his frank ideas on the divine world, which can be compared only with Sufi shath, he finishes the majority of verses in “Divan-e kebir” by expression "khamush" (be silent) and its semantic synonyms. These views of the well-known thinker are founded on sights that, “We know about current come, therefore our mouths are sealed…” Almost in each quatrain Mevlâna gives new and distinctive Sufi meaning of expression “khamush”, pursuing sometimes the purpose of concealment of divine true from crowd (“amm”) and another’s (“namahrem”), and sometimes means transition from “khamush” to “zeban-e bizebani” etc. In opinion of the thinker there is no necessity for the “letter”, “word” or “language” after “khamush”, because the true is expressed “by language without language” (“lisan-e bilisani”). Sometimes he simply is silent to listen to an internal voice. The expression “khamush” is closely connected with Sufi ideas on “mouth” of soul, internal sense organs (concerning to soul) and representations about “non-existence of mouth”, which often meets in Sufi classical poetry. In summary we have came to such conclusion, that “khamush” is not a pseudonym of Mevlâna, as assumed the majority of researchers, and is individual and original literary – mystic method as “ene’l-hakk”, which was a source of inspiration for the followers such as Yunus Emre, Nassimi and Fuzuli
Persian Gulf security arrangements, with special reference to Iran's foreign policy
No full textThe aim of this study is to provide a conceptual and analytical foundation for a discussion about the future shape of security arrangements in the Persian Gulf. The Persian Gulf is a regiion whose strategic and economic characteristics have strengthened its vital significance to all littoral states as well as the entire world's economy and political life. Its significant geopolitical situation, in addition to its dominant position as an energy source and gateway for global energy has caused this region to be a worthy rival to outside powers, particularly the West, while also being the most unstable and chaotic of any world region.
Therefore the objective of this thesis has been to provide a security model for the Persian Gulf that address the need for a stable and peaceful structure of relationships which will provide security for all individual littoral states, as well as assuring the interests of the external powers.
The thesis' hypothesis of cooperation as the only possible basis for a comprehensive strategy for peace and stability in this region has been substantiated by employing a variety of conceptual and analytical tools to understand the reasons for the failure of security models 'in the Persian Gulf and to confront the huge obstacles to a security system for this region. The relevance of this model is supported by the modem global political landscape, most especially the events that have occurred since the end of the 11 Cold War, in addition to various successful cooperation models that are to be found in other regions of the globe, e. g. the EU. This is assisted by the unprecedented opportunity for regional cooperation and the conditions for the creation of new security arrangements in the Persian Gulf and beyond that have been created since the downfall of Saddam's regime in 2003, which was one of the major elements of
insecurity in this region.
To this end, this study has analysed various security models in this significant geopolitical region in the world since 1962, with special reference to Iran's foreign policy. Particular reference has been made to Iran because of its geostrategic and geopolitical situation and as the hegemonic power in the Persian Gulf, which regardless its political regimes, it has great national and security concerns and plays a determinant role in peace and security of the region.
With emphasis on dialogue as the best solution to the regional security problems in the Persian Gulf, this study has come up with a pyramid security model on the basis of the region's geopolitical realities which emphasisesth e need for domestic reforms as well as interaction and cooperation and a balance of interests between all regional and non-regional players
