Perpetual emulation threshold of PT-symmetric Hamiltonians

We describe a technique to emulate a two-level \PT-symmetric spin Hamiltonian, replete with gain and loss, using only the unitary dynamics of a larger quantum system. This we achieve by embedding the two-level system in question in a subspace of a four-level Hamiltonian. Using an \textit{amplitude recycling} scheme that couples the levels exterior to the \PT-symmetric subspace, we show that it is possible to emulate the desired behaviour of the \PT-symmetric Hamiltonian without depleting the exterior, reservoir levels. We are thus able to extend the emulation time indefinitely, despite the non-unitary \PT dynamics. We propose a realistic experimental implementation using dynamically decoupled magnetic sublevels of ultracold atoms.Comment: 15 pages, 8 figure

Binding-incompetent adenovirus facilitates molecular conjugate-mediated gene transfer by the receptor-mediated endocytosis pathway

Molecular conjugate vectors may be constructed that accomplish high efficiency gene transfer by the receptor-mediated endocytosis pathway. In order to mediate escape from lysosomal degradation, we have incorporated adenoviruses into the functional design of the conjugate. In doing so, however, we have introduced an additional ligand, which can bind to receptors on the cell surface, undermining the potential for cell specific targeting. To overcome this, we have treated the adenovirus with a monoclonal anti-fiber antibody, which renders the virus incapable of binding to its receptor. The result is a multi-functional molecular conjugate vector, which has preserved its binding specificity while at the same time being capable of preventing lysosomal degradation of endosome-internalized conjugate-DNA complexes. This finding indicates that adenoviral binding is not a prerequisite for adenoviral-mediated endosome disruption

High-resolution study of a star-forming cluster in the Cep-A HW2 region

Due to its relatively small distance (725 pc), the Cepheus A East star-forming region is an ideal laboratory to study massive star formation processes. Based on its morphology, it has been suggested that the flattened molecular gas distribution around the YSO HW2 may be a 350-AU-radius massive protostellar disk. Goal of our work is to ascertain the nature of this structure. We have employed the Plateau de Bure Interferometer to acquire (sub-)arcsecond-resolution imaging of high-density and shock tracers, such as methyl cyanide (CH3CN) and silicon monoxide (SiO), towards the HW2 position. On the 1-arcsecond (about 725 AU) scale, the flattened distribution of molecular gas around HW2 appears to be due to the projected superposition, on the plane of the sky, of at least three protostellar objects, of which at least one is powering a molecular outflow at a small angle with respect to the line of sight. The presence of a protostellar disk around HW2 is not ruled out, but such structure is likely to be detected on a smaller spatial scale, or using different molecular tracers.Comment: 6 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

Finite element analysis of the damage mechanism of 3D braided composites under high-velocity impact

The integrated near-net-shape structure of 3D braided composites provides excellent impact resistant properties over laminated composites. However, the load distribution and damage mechanism throughout the braided structures become more complicated. In this paper, a finite element model based on three unit-cells is established to assess the penetration process of 3D braided composites under high-velocity impact. A 3D rate-dependent constitutive model is employed to determine the constituent behavior in the three unit-cells. An instantaneous degradation scheme is proposed initiated by appropriate failure criteria of yarns and matrix. All these constitutive models are coded by a user-material subroutine VUMAT developed in ABAQUS/Explicit. The whole process of ballistic damage evolution of 3D braided composites is simulated, and the impact resistance and damage mechanisms are analyzed in detail in the simulation process. The effects of impact velocity on the ballistic properties and energy absorption characteristics of the composite structures are also discussed

VLA 3.5 cm continuum sources in the Serpens cloud core

We present VLA 3.5 cm continuum observations of the Serpens cloud core. 22 radio continuum sources are detected. 16 out of the 22 cm sources are suggested to be associated with young stellar objects (Class 0, Class I, flat-spectrum, and Class II) of the young Serpens cluster. The rest of the VLA sources plausibly are background objects. Most of the Serpens cm sources likely represent thermal radio jets; on the other hand, the radio continuum emission of some sources could be due to a gyrosynchroton mechanism arising from coronally active young stars. The Serpens VLA sources are spatially distributed into two groups; one of them located towards the NW clump of the Serpens core, where only Class 0 and Class I protostars are found to present cm emission, and a second group located towards the SE clump, where radio continuum sources are associated with objects in evolutionary classes from Class 0 to Class II. This subgrouping is similar to that found in the near IR, mid-IR and mm wavelength regimes.Comment: 2 figures, accepted by Astronomical journa

The metaphysics of Machian frame-dragging

The paper investigates the kind of dependence relation that best portrays Machian frame-dragging in general relativity. The question is tricky because frame-dragging relates local inertial frames to distant distributions of matter in a time-independent way, thus establishing some sort of non-local link between the two. For this reason, a plain causal interpretation of frame-dragging faces huge challenges. The paper will shed light on the issue by using a generalized structural equation model analysis in terms of manipulationist counterfactuals recently applied in the context of metaphysical enquiry by Schaffer (2016) and Wilson (2017). The verdict of the analysis will be that frame-dragging is best understood in terms of a novel type of dependence relation that is half-way between causation and grounding

Political influencers. A study of Donald Trump’s personal brand on Twitter and its impact on the media and users

The personality of a political candidate, above and beyond governments and parties, is understood increasingly more as a brand image. The new political influencers are making a clean sweep of social networks and it is the media that reproduce an information model that, far from being grounded in transparency and quality, promotes a post-truth discourse, halfway between provocation and spectacle. This initial hypothesis focuses on Donald Trump’s profile, first as a presidential candidate and later on as US President. In parallel, Twitter users have swiftly succumbed to the leader’s appeal. Thus, this paper studies the impact of Trump’s tweets on the US reference press during the first 100 days of his presidency. More specifically, it analyses the correspondences between the tweets posted on his personal Twitter account (@realDonaldTrump, with more than 45 million followers) and the front page news in USA Today, The Boston Globe, The Wall Street Journal and The New York Times. Regarding public response, digital prosumer metrics (“likes,” retweets and comments) have been quantified in order to verify the degree of influence exerted by Trump on public opinion. The method employed here includes a quantitative and qualitative content analysis based on three categories: the politician’s tweets, front page news and online user metrics. The results confirm Trump’s empowerment on Twitter as both a main source of news and a political influencer as regards the media and the citizenry.La individualidad del candidato político se postula cada vez más como imagen de marca, por delante de partidos y gobiernos. Los nuevos influencers de la Política copan las redes y son los medios de comunicación quienes reproducen un modelo informativo que, lejos de la transparencia y la calidad, promueve el discurso de la postverdad, entre la provocación y el espectáculo. Una hipótesis que se focaliza en el perfil de Donald Trump, primero como candidato a las elecciones americanas y más tarde como presidente de EUA. En paralelo, los usuarios de Twitter sucumben a la atracción del líder a golpe de clic. La investigación estudia el impacto de los tuits de Trump sobre la agenda de la prensa americana de referencia durante los primeros cien días de Gobierno. Se analiza la equivalencia entre los tuits emitidos desde la propia cuenta personal (@realDonaldTrump –con más de 45 millones de seguidores– y las portadas de los periódicos USA Today, The Boston Globe, The Wall Street Journal y The New York Times. En orden a la respuesta ciudadana, se cuantifican las métricas (favoritos, retuits y comentarios) de los prosumidores digitales para comprobar los niveles de influencia que ejerce Trump sobre la opinión pública. El método comprende un análisis de contenido de corte cuantitativo y cualitativo-discursivo mediante una categorización triangulada: tuits del político, portadas mediáticas y métricas del usuario online. Los resultados confirman el empoderamiento de Trump en Twitter, como principal generador de noticias e influencer político de medios y ciudadanos