Quantum theory of spin waves in finite chiral spin chains

We calculate the effect of spin waves on the properties of finite-size spin chains with a chiral spin ground state observed on biatomic Fe chains deposited on iridium(001). The system is described with a Heisenberg model supplemented with a Dzyaloshinskii-Moriya coupling and a uniaxial single ion anisotropy that presents a chiral spin ground state. Spin waves are studied using the Holstein-Primakoff boson representation of spin operators. Both the renormalized ground state and the elementary excitations are found by means of Bogoliubov transformation, as a function of the two variables that can be controlled experimentally, the applied magnetic field and the chain length. Three main results are found. First, because of the noncollinear nature of the classical ground state, there is a significant zero-point reduction of the ground-state magnetization of the spin spiral. Second, there is a critical external field from which the ground state changes from chiral spin ground state to collinear ferromagnetic order. The character of the two lowest-energy spin waves changes from edge modes to confined bulk modes over this critical field. Third, in the spin-spiral state, the spin-wave spectrum exhibits oscillatory behavior as function of the chain length with the same period of the spin helix.

The theory of the gene, by Thomas Hunt Morgan ...

2d ed

Expertise in Ultra-Endurance Triathletes Early Sport Involvement, Training Structure, and the Theory of Deliberate Practice

The theory of deliberate practice (Ericsson, Krampe, & Tesch-Römer, 1993) is predicated on the concept that the engagement in specific forms of practice is necessary for the attainment of expertise. The purpose of this paper was to examine the quantity and type of training performed by expert UE triathletes. Twenty-eight UE triathletes were stratified into expert, middle of the pack, and back of the pack groups based on previous finishing times. All participants provided detailed information regarding their involvement in sports in general and the three triathlon sports in particular. Results illustrated that experts performed more training than non-experts but that the relationship between training and performance was not monotonic as suggested by Ericsson et al. Further, experts' training was designed so periods of high training stress were followed by periods of low stress. However, early specialization was not a requirement for expertise. This work indicates that the theory of deliberate practice does not fully explain expertise development in UE triathlon.

The Theory of Interhybridity: Socio-political Dimensions and Migration Experiences of Post-communist Western Balkan States

The Western Balkans integration within the EU has started a legal process which is the rejection of former communist legal/political approaches and the transformation of former communist institutions. Indeed, the EU agenda has brought vertical/horizontal integration and Europeanization of national institutions (i.e. shifting power to the EU institutions and international authorities). At this point, it is very crucial to emphasize the fact that the Western Balkans as a whole region has currently an image that includes characteristics of both the Soviet socialism and the European democracy. The EU foreign policies and enlargement strategy for Western Balkans have significant effects on four core factors (i.e. Schengen visa regulations, remittances, asylum and migration as an aggregate process). The convergence/divergence of EU member states’ priorities for migration policies regulate and even shape directly the migration dynamics in migrant sender countries. From this standpoint, the research explores how main migration factors are influenced by political and judicial factors such as; rule of law and democracy score, the economic liberation score, political and human rights, civil society score and citizenship rights in Western Balkan countries. The proposal of interhybridity explores how the hybridization of state and non-state actors within home and host countries can solve labor migration-related problems. The economical and sociopolitical labor-migration model of Basu (2009) is overlapping with the multidimensional empirical framework of interhybridity. Indisputably, hybrid model (i.e. collaboration state and non-state actors) has a catalyst role in terms of balancing social problems and civil society needs. Paradigmatically, it is better to perceive the hybrid model as a combination of communicative and strategic action that means the reciprocal recognition within the model is precondition for significant functionality. This will shape social and industrial relations with moral meanings of communication.

Theory of many-particle correlations and optical properties of semiconductor quantum dots : photons and quantum dots

Otto-von-Guericke-Universität Magdeburg, Fakultät für Naturwissenschaften, Dissertation, 2016

Recognition; with an outline of a theory of knowledge.

Mode of access: Internet.