Polariton excitation in epsilon-near-zero slabs: transient trapping of slow light

We numerically investigate the propagation of a spatially localized and quasi-monochromatic electromagnetic pulse through a slab with Lorentz dielectric response in the epsilon-near-zero regime, where the real part of the permittivity vanishes at the pulse carrier frequency. We show that the pulse is able to excite a set of virtual polariton modes supported by the slab, the excitation undergoing a generally slow damping due to absorption and radiation leakage. Our numerical and analytical approaches indicate that in its transient dynamics the electromagnetic field displays the very same enhancement of the field component perpendicular to the slab, as in the monochromatic regime. The transient trapping is inherently accompanied by a significantly reduced group velocity ensuing from the small dielectric permittivity, thus providing a novel platform for achieving control and manipulation of slow light

An exact Coulomb cutoff technique for supercell calculations

We present a new reciprocal space analytical method to cutoff the long range interactions in supercell calculations for systems that are infinite and periodic in 1 or 2 dimensions, extending previous works for finite systems. The proposed cutoffs are functions in Fourier space, that are used as a multiplicative factor to screen the bare Coulomb interaction. The functions are analytic everywhere but in a sub-domain of the Fourier space that depends on the periodic dimensionality. We show that the divergences that lead to the non-analytical behaviour can be exactly cancelled when both the ionic and the Hartree potential are properly screened. This technique is exact, fast, and very easy to implement in already existing supercell codes. To illustrate the performance of the new scheme, we apply it to the case of the Coulomb interaction in systems with reduced periodicity (as one-dimensional chains and layers). For those test cases we address the impact of the cutoff in different relevant quantities for ground and excited state properties, namely: the convergence of the ground state properties, the static polarisability of the system, the quasiparticle corrections in the GW scheme and in the binding energy of the excitonic states in the Bethe-Salpeter equation. The results are very promising.Comment: Submitted to Physical Review B on Dec 23rd 200

The Building Information Model and the IFC standard: analysis of the characteristics necessary for the acoustic and energy simulation of buildings

The new European Directive 2014/24 / EU requires for all member States the use of BIM procedures in the construction of public buildings. The countries belonging to the European Union shall be obliged to transpose the Directive and adapt their procedures to that effect. The paper analyzes the IFC format, the only recognized by the European Directive Standards for BIM procedures, in order to assess its use for simulations of buildings. IFC, described by the ISO 16739 (2013), is today a standard that describes the topology of the constructive elements of the building and what belongs to it overall. The format includes geometrical information on the room and on all building components, including details of the type for performance (transmittance, fire resistance, sound insulation), in other words it is an independent object file for the software producers to which, according to the European Directive, it will be compulsory to refer in the near future, during the different stages of the life of a building from the design phase, to management and possible demolition at the end of life. The IFC initiative began in 1994, when an industry consortium invested in the development of a set of C ++ classes that can support the development of integrated applications. Twelve US companies joined the consortium: these companies that were included initially are called the consortium "Industry Alliance for Interoperability". In September 1995 the Alliance opened up membership to all interested parties, and in 1997 changed its name to "International Alliance for Interoperability". The new alliance was reconstituted as a non-profit organization, with the aim of developing and promoting the '' Industry Foundation Class "(IFC) as a neutral data model for the building product that were useful to gather information throughout the life cycle of a building facility. Since 2005 the Alliance has been carrying out its activities through its national chapters called SMART building. The present study aims at evaluating the IFC, comparing the information and data contained in it, with other formats already used for energy simulations of buildings such as the gbXML (Green Building XML), highlighting the missing required information and proposing the inclusion of new ones to issue the energy and acoustic simulation. More generally the attention is focused to building physics simulation software devoted to exploit the BIM model potential enabling interoperability

Unenhanced whole-body MRI versus PET-CT for the detection of prostate cancer metastases after primary treatment

The aim of this study was to evaluate the accuracy of unenhanced whole-body MRI, including whole-body Diffusion Weighted Imaging (DWI), used as a diagnostic modality to detect  pathologic lymph nodes and skeletal metastases in patients with prostate cancer (PCa) undergoing restaging after primary treatment

Enhanced asymmetric transmission in hyperbolic epsilon-near-zero slabs

CR and AC thank the US Army International Technology Center Atlantic for financial support (Grant No. W911NF-14-1-0315). This work has partially been supported by the CNR-SPIN Seed Project No. B52F17001370005. AM acknowledges support from the 'Rita Levi Montalcini' programme for the recruitment of young researchers. CR and EP acknowledges support from the project NANOPREPAINT—PAR FSC Abruzzo 2007–2013—Linea di Azione I.1.1.a.We investigate the asymmetric transmission for forward and backward propagation of tilted circular polarized optical waves in subwavelength epsilon-near-zero (ENZ) hyperbolic slabs. This chiral-optical effect is solely triggered by anisotropy without resorting to any breaking of reciprocity and chiral symmetries or spatial nonlocal effects. Remarkably, we show that the asymmetric transmission undergoes a dramatic enhancement near the ENZ condition. This happens since, close to the zero-crossing point, the extraordinary waves can accumulate the desired propagation phase even though the slab is ultrathin and, by varying excitation angles and slab thickness, we engineer this phase thus achieving a huge asymmetric transmission. The proposed strategy holds promise for realizing ultra-compact and efficient polarization devices in different frequency range even at very high frequencies (ultraviolet) since the effect is merely due to anisotropy and it is available without resorting to nanofabrication processes.PostprintPeer reviewe

Only Words Count; the Rest Is Mere Chattering: A Cross-Disciplinary Approach to the Verbal Expression of Emotional Experience

The analysis of sequences of words and prosody, meter, and rhythm provided in an interview addressing the capacity to identify and describe emotions represents a powerful tool to reveal emotional processing. The ability to express and identify emotions was analyzed by means of the Toronto Structured Interview for Alexithymia (TSIA), and TSIA transcripts were analyzed by Natural Language Processing to shed light on verbal features. The brain correlates of the capacity to translate emotional experience into words were determined through cortical thickness measures. A machine learning methodology proved that individuals with deficits in identifying and describing emotions (n = 7) produced language distortions, frequently used the present tense of auxiliary verbs, and few possessive determiners, as well as scarcely connected the speech, in comparison to individuals without deficits (n = 7). Interestingly, they showed high cortical thickness at left temporal pole and low at isthmus of the right cingulate cortex. Overall, we identified the neuro-linguistic pattern of the expression of emotional experience