Equilibration in phi^4 theory in 3+1 dimensions

The process of equilibration in phi^4 theory is investigated for a homogeneous system in 3+1 dimensions and a variety of out-of-equilibrium initial conditions, both in the symmetric and broken phase, by means of the 2PI effective action. Two Phi-derivable approximations including scattering effects are used: the two-loop and the ``basketball'', the latter corresponding to the truncation of the 2PI effective action at O(lambda^2). The approach to equilibrium, as well as the kinetic and chemical equilibration is investigated.Comment: 32 pages, 14 figures, uses axodraw, minor corrections adde

Scaffold Stiffness Influences Cell Behavior: Opportunities for Skeletal Tissue Engineering

Skeletal defects resulting from trauma, tumors, or abnormal development frequently require surgical treatment to restore normal tissue function. To overcome the limitations associated with conventional surgical treatments, several tissue engineering approaches have been developed. In particular, the use of scaffolds enriched with stem cells appears to be a very promising strategy. A crucial issue in this approach is how to control stem cell behavior. In this respect, the effects of growth factors, scaffold surface characteristics, and external ‘active’ loading conditions on stem cell behavior have been investigated. Recently, it has become clear that the stiffness of a scaffold is a highly potent regulator of stem cell differentiation. In addition, the stiffness of a scaffold affects cell migration, which is important for the infiltration of host tissue cells. This review summarizes current knowledge on the role of the scaffold stiffness in the regulation of cell behavior. Furthermore, we discuss how this knowledge can be incorporated in scaffold design which may provide new opportunities in the context of orthopedic tissue engineering

Continuum Gauge Fields from Lattice Gauge Fields

On the lattice some of the salient features of pure gauge theories and of gauge theories with fermions in complex representations of the gauge group seem to be lost. These features can be recovered by considering part of the theory in the continuum. The prerequisite for that is the construction of continuum gauge fields from lattice gauge fields. Such a construction, which is gauge covariant and complies with geometrical constructions of the topological charge on the lattice, is given in this paper. The procedure is explicitly carried out in the $U(1)$ theory in two dimensions, where it leads to simple results.Comment: 16 pages, HLRZ 92-3

Polarization manipulation in photonic integration on indium phosphide

The possibility to manipulate polarization in a Photonic Integrated Circuit (PIC) gives new design options. This will be illustrated with POLIS, an integration scheme based on polarization. Also the polarization manipulating devices will be introduced

Особливості правового регулювання ліцензування господарської діяльності у сфері обігу дорогоцінного каміння

Здійснення господарської діяльності, на сьогодні, в нашій державі постійно трансформуються залежно від встановлених і закріплених в нормативно правових актах визначених і регульованих державою процедур, зокрема, шляхом ліцензування господарської діяльності, тому державна галузева політика у сфері діяльності суб’єктів господарювання, пов’язаної з дорогоцінними металами і дорогоцінним камінням має бути відрегульована належним чином не тільки через призму ліцензування, але й з урахуванням забезпечення балансу економіки та національної економічної безпеки країни. Ключові слова: ліцензування, ліцензія, господарська діяльність, процедура, нагляд, контроль, суб’єкти господарювання, дорогоцінні метали і каміння, використання дорогоцінних металів і дорогоцінного каміння.Осуществление хозяйственной деятельности, на сегодня, в нашем государстве постоянно трансформируются в зависимости от установленных и закрепленных в нормативно-правовых актах определенных и регулируемых государством процедур, в частности, путем лицензирования хозяйственной деятельности, поэтому государственная отраслевая политика в сфере деятельности субъектов ведения хозяйства, связанной с драгоценными металлами и драгоценными камнями должена быть отрегулирована должным образом не только через призму лицензирования, но и с учетом обеспечения баланса экономики и национальной экономической безопасности государства. Ключевые слова: лицензирование, лицензия, хозяйственная деятельность, процедура, контроль, субъекты ведения хозяйства, драгоценные металлы и камни, использование драгоценных металлов и драгоценных камней.Realization of enterprising movement, nowadays, in our state constantly transformed depending on position and envisaged in the normatively-legal acts of certain and managed by the state procedures, in particular, by licensing of enterprising, that is why public branch policy in the field of activity of enterprises, related to the precious metals and jewels must be adjusted properly not only through the prism of licensing but also taking into account providing of balance of economy and national economic security of a state. Key words: licensing, license, economic activity, procedure, supervision, control, enterprises, precious metals and stones, apply of precious metals and precious stones

Resistance of a domain wall in the quasiclassical approach

Starting from a simple microscopic model, we have derived a kinetic equation for the matrix distribution function. We employed this equation to calculate the conductance $G$ in a mesoscopic F'/F/F' structure with a domain wall (DW). In the limit of a small exchange energy $J$ and an abrupt DW, the conductance of the structure is equal to $G_{2d}=4\sigma_{\uparrow}\sigma_{\downarrow }/(\sigma_{\uparrow}+\sigma_{\downarrow})L$. Assuming that the scattering times for electrons with up and down spins are close to each other we show that the account for a finite width of the DW leads to an increase in this conductance. We have also calculated the spatial distribution of the electric field in the F wire. In the opposite limit of large $J$ (adiabatic variation of the magnetization in the DW) the conductance coincides in the main approximation with the conductance of a single domain structure $G_{1d}=(\sigma_{\uparrow}+\sigma_{\downarrow})/L$. The account for rotation of the magnetization in the DW leads to a negative correction to this conductance. Our results differ from the results in papers published earlier.Comment: 11 pages; replaced with revised versio

Tunneling broadening of vibrational sidebands in molecular transistors

Transport through molecular quantum dots coupled to a single vibration mode is studied in the case with strong coupling to the leads. We use an expansion in the correlation between electrons on the molecule and electrons in the leads and show that the tunneling broadening is strongly suppressed by the combination of the Pauli principle and the quantization of the oscillator. As a consequence the first Frank-Condon step is sharper than the higher order ones, and its width, when compared to the bare tunneling strength, is reduced by the overlap between the groundstates of the displaced and the non-displaced oscillator.Comment: 8 pages, 3 figures. PRB, in pres