Revisiting Rotational Perturbations and the Microwave Background

We consider general-relativistic rotational perturbations in homogeneous and isotropic Friedman - Robertson - Walker (FRW) cosmologies. Taking linear perturbations of FRW models, the general solution of the field equations contains tensorial, vectorial and scalar functions. The vectorial terms are in connection with rotations in the given model and due to the Sachs - Wolfe effect they produce contributions to the temperature fluctuations of the cosmic microwave background radiation (CMBR). In present paper we obtain the analytic time dependence of these contributions in a spatially flat, FRW model with pressureless ideal fluid, in the presence and the absence of a cosmological constant. We find that the solution can be separated into an integrable and a non-integrable part as is the situation in the case of scalar perturbations. Analyzing the solutions and using the results of present observations we estimate the order of magnitude of the angular velocity corresponding to the rotation tensor at the time of decoupling and today.Comment: accepted for publication in Int. J. Mod. Phys.

Gravitational waves from binaries on unbound orbits

A generalized true anomaly-type parametrization, convenient to describe both bound and open orbits of a two-body system in general relativity is introduced. A complete description of the time evolution of both the radial and of the angular equations of a binary system taking into account the first order post-newtonian (1PN) is given. The gravitational radiation field emitted by the system is computed in the 1PN approximation including higher multipole moments beyond the standard quadrupole term. The gravitational waveforms in the time domain are explicitly given up to the 1PN order for unbound orbits, but the results are also illustrated on binaries on elliptic orbits with special attention given to the effects of eccentricity.Comment: 27 pages, 10 figures, to appear in Phys. Rev.

Covariant Linear Perturbations in a Concordance Model

We present the complete solution of the first order metric and density perturbation equations in a spatially flat (K=0), Friedmann-Robertson-Walker (FRW) universe filled with pressureless ideal fluid, in the presence of cosmological constant. We use covariant linear perturbation formalism and the comoving gauge condition to obtain the field and conservation equations. The solution contains all modes of the perturbations, i.e. scalar, vector and tensor modes, and we show that our results are in agreement with the Sachs & Wolfe metric perturbation formalism.Comment: 8 page

Effect of <i>tert</i>-Butyl Functionalization on the Photoexcited Decay of a Fe(II)-<i>N</i>-Heterocyclic Carbene Complex

Understanding and subsequently being able to manipulate the excited-state decay pathways of functional transition-metal complexes is of utmost importance in order to solve grand challenges in solar energy conversion and data storage. Herein, we perform quantum chemical calculations and spin-vibronic quantum dynamics simulations on the Fe-<i>N</i>-heterocyclic carbene complex, [Fe­(btbip)₂]²⁺ (btbip = 2,6-bis­(3-<i>tert</i>-butyl-imidazole-1-ylidene)­pyridine). The results demonstrate that a relatively minor structural change compared to its parent complex, [Fe­(bmip)₂]²⁺ (bmip = 2,6-bis­(3-methyl-imidazole-1-ylidene)­pyridine), completely alters the excited-state relaxation. Ultrafast deactivation of the initially excited metal-to-ligand charge transfer (^1,3MLCT) states occurs within 350 fs. In contrast to the widely adopted mechanism of Fe­(II) photophysics, these states decay into close-lying singlet metal-centered (¹MC) states. This occurs because the <i>tert</i>-butyl functionalization stabilizes the ¹MC states, enabling the ^1,3MLCT → ¹MC population transfer to occur close to the Franck–Condon geometry, making the conversion very efficient. Subsequently, a spin cascade occurs within the MC manifold, leading to the population of triplet and quintet MC states. These results will inspire highly involved ultrafast experiments performed at X-ray free electron lasers and shall pave the way for the design of novel high-efficiency transition-metal-based functional molecules

The fear circuit of the mouse forebrain: connections between the mediodorsal thalamus, frontal cortices and basolateral amygdala

A large forebrain circuit, including the thalamus, amygdala and frontal cortical regions, is responsible for the establishment and extinction of fear-related memories. Understanding interactions among these three regions is critical to deciphering the basic mechanisms of fear. With the advancement of molecular and optogenetics techniques, the mouse has become the main species used to study fear-related behaviours. However, the basic connectivity pattern of the forebrain circuits involved in processing fear has not been described in this species. In this study we mapped the connectivity between three key nodes of the circuit, i.e. the basolateral nucleus of the amygdala (BLA), the mediodorsal nucleus of the thalamus (MD) and the medial prefrontal cortex, which were shown to have closed triangular connectivity in rats. In contrast to rat, we found no evidence for this closed loop in mouse. There was no major input from the BLA to the MD and little overlap between medial prefrontal regions connected with both the BLA and MD. The common nodes in the frontal cortex, which displayed reciprocal connection with both the BLA and MD were the agranular insular cortex and the border zone of the cingulate and secondary motor cortex. In addition, the BLA can indirectly affect the MD via the orbital cortex. We attribute the difference between our results and earlier rat studies to methodological problems rather than to genuine species difference. Our data demonstrate that the BLA and MD communicate via cortical sectors, the roles in fear-related behaviour of which have not been extensively studied. In general, our study provides the morphological framework for studies of murine fear-related behaviours

A multibaker map for shear flow and viscous heating

A consistent description of shear flow and the accompanied viscous heating as well the associated entropy balance is given in the framework of a deterministic dynamical system. A laminar shear flow is modeled by a Hamiltonian multibaker map which drives velocity and temperature fields. In an appropriate macroscopic limit one recovers the Navier-Stokes and heat conduction equations along with the associated entropy balance. This indicates that results of nonequilibrium thermodynamics can be described by means of an abstract, sufficiently chaotic and mixing dynamics. A thermostating algorithm can also be incorporated into this framework.Comment: 11 pages; RevTex with multicol+graphicx packages; eps-figure

Maximizing nearest neighbour entanglement in finitely correlated qubit--chains

We consider translationally invariant states of an infinite one dimensional chain of qubits or spin-1/2 particles. We maximize the entanglement shared by nearest neighbours via a variational approach based on finitely correlated states. We find an upper bound of nearest neighbour concurrence equal to C=0.434095 which is 0.09% away from the bound C_W=0.434467 obtained by a completely different procedure. The obtained state maximizing nearest neighbour entanglement seems to approximate the maximally entangled mixed states (MEMS). Further we investigate in detail several other properties of the so obtained optimal state.Comment: 12 pages, 4 figures, 2nd version minor change

Gyakorlóiskola (1914) 5

Magyar Tanítóképző A Tanítóképző-intézeti Tanárok Országos Egyesületének közlönye - melléklet 29. évfolyam Budapest, 1914. május h