Giant vortices, vortex rings and reentrant behavior in type-1.5 superconductors

We predict that in a bulk type-1.5 superconductor the competing magnetic responses of the two components of the order parameter can result in a vortex interaction that generates group-stabilized giant vortices and unusual vortex rings in the absence of any extrinsic pinning or confinement mechanism. We also find within the Ginzburg-Landau theory a rich phase diagram with successions of behaviors like type-1 -> type-1.5 -> type-2 -> type-1.5 as temperature decreases.Comment: 5 pages, 4 figure

CEMENT SELECTION IN DENTAL PRACTICE

The cementation procedure is considered to be the most important stage of fixed prosthodontics, while the correct selection of cement is the guarantee of successful restoration which is conditioned by the its durability. Over the recent years, numerous cementing substances have been introduced to the dental practice that differ greatly from conventional cements with their properties and application methods and that is why even experienced dentists often have certain difficulties in the variety of cements to choose the one that is right for each clinical case. The selection of cement depends on a number of factors, such as the type of resorption substance, the shape of prepared tooth, the possibility to isolate the area, subject to cementation in the oral cavity as well as the patient’s aesthetic requirements. Thus, the objective of the article is to analyze currently used dental cements in order to help the dentists make the right selection of cement for different clinical cases.The cementation procedure is considered to be the most important stage of fixed prosthodontics, while the correct selection of cement is the guarantee of successful restoration which is conditioned by the its durability. Over the recent years, numerous cementing substances have been introduced to the dental practice that differ greatly from conventional cements with their properties and application methods and that is why even experienced dentists often have certain difficulties in the variety of cements to choose the one that is right for each clinical case. The selection of cement depends on a number of factors, such as the type of resorption substance, the shape of prepared tooth, the possibility to isolate the area, subject to cementation in the oral cavity as well as the patient’s aesthetic requirements. Thus, the objective of the article is to analyze currently used dental cements in order to help the dentists make the right selection of cement for different clinical cases

Fermionic vacuum currents in topologically nontrivial braneworlds: Two-brane geometry

The vacuum expectation value (VEV) of the fermionic current density is investigated in the geometry of two parallel branes in locally AdS spacetime with a part of spatial dimensions compactified to a torus. Along the toral dimensions quasiperiodicity conditions are imposed with general phases and the presence of a constant gauge field is assumed. Different types of boundary conditions are discussed on the branes, including the bag boundary condition and the conditions arising in $Z_{2}$-symmetric braneworld models. Nonzero vacuum currents appear along the compact dimensions only. In the region between the branes they are decomposed into the brane-free and brane-induced contributions. Both these contributions are periodic functions of the magnetic flux enclosed by compact dimensions with the period equal to the flux quantum. Depending on the boundary conditions, the presence of the branes can either increase or decrease the vacuum current density. For a part of boundary conditions, a memory effect is present in the limit when one of the branes tends to the AdS boundary. Unlike to the fermion condensate and the VEV of the energy-momentum tensor, the VEV of the current density is finite on the branes. Applications are given to higher-dimensional generalizations of the Randall-Sundrum models with two branes and with toroidally compact subspace. The features of the fermionic current are discussed in odd-dimensional parity and time-reversal symmetric models. The corresponding results for three-dimensional spacetime are applied to finite length curved graphene tubes threaded by a magnetic flux. It is shown that a nonzero current density can also appear in the absence of the magnetic flux if the fields corresponding to two different points of the Brillouin zone obey different boundary conditions on the tube edges.Comment: 33 pages, 7 figures, PACS numbers: 04.62.+v, 03.70.+k, 98.80.-k, 61.46.F

Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid

We analyze magnetic flux tubes at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient (``entrainment'') interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is general and simple, modeling the interactions as a Ginzburg-Landau effective theory with four-fermion couplings, including only s-wave pairing. We numerically solve the field equations for flux tubes with an arbitrary number of flux quanta, and compare their energies. This allows us to map the type-I/type-II transition in the superconductor, which occurs at the conventional kappa = 1/sqrt(2) if the condensates are uncoupled. We find that a density coupling between the condensates raises the critical kappa and, for a sufficiently high neutron density, resolves the type-I/type-II transition line into an infinite number of bands corresponding to ``type-II(n)'' phases, in which n, the number of quanta in the favored flux tube, steps from 1 to infinity. For lower neutron density, the coupling creates spinodal regions around the type-I/type-II boundary, in which metastable flux configurations are possible. We find that a gradient coupling between the condensates lowers the critical kappa and creates spinodal regions. These exotic phenomena may not occur in nuclear matter, which is thought to be deep in the type-II region, but might be observed in condensed matter systems.Comment: 14 pages, improved discussion of the effects of varying the neutron/proton condensate ratio; added reference

Oscillations of General Relativistic Multi-fluid/Multi-layer Compact Stars

We develop the formalism for determining the quasinormal modes of general relativistic multi-fluid compact stars in such a way that the impact of superfluid gap data can be assessed. Our results represent the first attempt to study true multi-layer dynamics, an important step towards considering realistic superfluid/superconducting compact stars. We combine a relativistic model for entrainment with model equations of state that explicity incorporate the symmetry energy. Our analysis emphasises the many different parameters that are required for this kind of modelling, and the fact that standard tabulated equations of state are grossly incomplete in this respect. To make progress, future equations of state need to provide the energy density as a function of the various nucleon number densities, the temperature (i.e. entropy), and the entrainment among the various components

Nonequilibrium electrons in tunnel structures under high-voltage injection

We investigate electronic distributions in nonequilibrium tunnel junctions subject to a high voltage bias $V$ under competing electron-electron and electron-phonon relaxation processes. We derive conditions for reaching quasi-equilibrium and show that, though the distribution can still be thermal for low energies where the rate of the electron-electron relaxation exceeds significantly the electron-phonon relaxation rate, it develops a power-law tail at energies of order of $eV$. In a general case of comparable electron-electron and electron-phonon relaxation rates, this tail leads to emission of high-energy phonons which carry away most of the energy pumped in by the injected current.Comment: Revised versio

The probable evidence of leprosy in a male individual unearthed in medieval Armenia (Angeghakot)

The objective of this study is to present the paleopathological lesions relevant to the discussion of the differential diagnosis of leprosy. Macroscopic, histological and X-ray observation of the bones and scrutiny of lesions according to the paleopathological literature allowed the identification of a probable case of leprosy in an adult male from Angeghakot (Early Middle Age, skeleton 4). The skeleton of a male (50–55 years) revealed several bony changes indicative of leprosy with clear rhino-maxillary syndrome. There is a scarcity of information in the osteoarchaeological literature of leprosy in ancient Armenia. The significance of this case is that it adds to an understanding of the history of the disease in Armenia and to the data set necessary to understand the epidemiological dynamics in the South Caucasus during the Early Middle Ages