Superdescendants of the D1D5 CFT and their dual 3-charge geometries

We describe how to obtain the gravity duals of semiclassical states in the D1-D5 CFT that are superdescendants of a class of RR ground states. On the gravity side, the configurations we construct are regular and asymptotically reproduce the 3-charge D1-D5-P black hole compactified on $S^1\times T^4$. The geometries depend trivially on the $T^4$ directions but non-trivially on the remaining 6D space. In the decoupling limit, they reduce to asymptotically AdS$_3 \times S^3 \times T^4$ spaces that are dual to CFT states obtained by acting with (exponentials of) the operators of the superconformal algebra. As explicit examples, we generalise the solution first constructed in arXiv:1306.1745 and discuss another class of states that have a more complicated dual geometry. By using the free orbifold description of the CFT we calculate the average values for momentum and the angular momenta of these configurations. Finally we compare the CFT results with those obtained in the bulk from the asymptotically $M^{1,4} \times S^1\times T^4$ region.Comment: 50 pages; v2: corrected typos; v3: corrected typos, eq. (2.9b) simplifie

Parametric Surfaces for Augmented Architecture representation

Augmented Reality (AR) represents a growing communication channel, responding to the need to expand reality with additional information, offering easy and engaging access to digital data. AR for architectural representation allows a simple interaction with 3D models, facilitating spatial understanding of complex volumes and topological relationships between parts, overcoming some limitations related to Virtual Reality. In the last decade different developments in the pipeline process have seen a significant advancement in technological and algorithmic aspects, paying less attention to 3D modeling generation. For this, the article explores the construction of basic geometries for 3D model’s generation, highlighting the relationship between geometry and topology, basic for a consistent normal distribution. Moreover, a critical evaluation about corrective paths of existing 3D models is presented, analysing a complex architectural case study, the virtual model of Villa del Verginese, an emblematic example for topological emerged problems. The final aim of the paper is to refocus attention on 3D model construction, suggesting some "good practices" useful for preventing, minimizing or correcting topological problems, extending the accessibility of AR to people engaged in architectural representation

The Influence of Colour on Radiometric Performances of Agricultural Nets

The whole construction parameters of the net, combined with the shape of the structure, the position of the sun and the sky conditions affect the radiometric performance of the permeable covering system. The radiometric properties of the permeable membrane influence the quality of the agricultural production and the aesthetic characteristics of the netting system. Moreover, the colour of the material and the light reflection- especially of the wavelengths visible for the human eye (VIS, 380-760nm)- is an interesting criterion to determine the aesthetic value of the net structure and its environmental impact. In order to investigate the influence of the threads colour on the radiometric properties of the net, a set of field tests were performed by means of a spectroradiometer in combination with an experimental setup 120x120x50cm covered with membranes formed by threads with different colour. A second set of experiments were performed, on the same kind of nets, in laboratory by means of a combination of a large integrating sphere and a small one: the transmissivity from a direct (tauDIR) and diffuse ((tauDIF) source and the reflectivity from diffuse source (¿) of 50x50cm samples were measured in the PAR range. The evaluation of the transmissivity values shows that the colour of a net influence spectral distribution of the radiation passing through the net absorbing their complementary colours. The transmissivity of black nets is almost constant in the visible range and the reduction of the incoming radiation is proportional to the solidity of the net. In the PAR range transparent and black nets doesn¿t cause an alteration of the spectrum of solar radiation and transmittance is almost constant with a slight growth in nets having lower porosity

Innovation, generative relationships and scaffolding structures: implications of a complexity perspective to innovation for public and private interventions

The linear model of innovation has been superseded by a variety of theoretical models that view the innovation process as systemic, complex, multi-level, multi-temporal, involving a plurality of heterogeneous economic agents. Accordingly, the emphasis of the policy discourse has changed over time. The focus has shifted from the direct public funding of basic research as an engine of innovation, to the creation of markets for knowledge goods, to, eventually, the acknowledgement that knowledge transfer very often requires direct interactions among innovating actors. In most cases, policy interventions attempt to facilitate the match between “demand” and “supply” of the knowledge needed to innovate. A complexity perspective calls for a different framing, one focused on the fostering of processes characterized by multiple agency levels, multiple temporal scales, ontological uncertainty and emergent outcomes. This contribution explores what it means to design interventions in support of innovation processes inspired by a complex systems perspective. It does so by analyzing two examples of coordinated interventions: a public policy funding innovating networks (with SMEs, research centers and university), and a private initiative, promoted by a network of medium-sized mechanical engineering firms, that supports innovation by means of technology brokerage. Relying on two unique datasets recording the interactions of the organizations involved in these interventions, social network analysis and qualitative research are combined in order to investigate network dynamics and the roles of specific actors in fostering innovation processes. Then, some general implications for the design of coordinated interventions supporting innovation in a complexity perspective are drawn

Tuning the electronic transport properties of graphene through functionalisation with fluorine

Engineering the electronic properties of graphene has triggered great interest for potential applications in electronics and opto-electronics. Here we demonstrate the possibility to tune the electronic transport properties of graphene monolayers and multilayers by functionalisation with fluorine. We show that by adjusting the fluorine content different electronic transport regimes can be accessed. For monolayer samples, with increasing the fluorine content, we observe a transition from electronic transport through Mott variable range hopping in two dimensions to Efros - Shklovskii variable range hopping. Multilayer fluorinated graphene with high concentration of fluorine show two-dimensional Mott variable range hopping transport, whereas CF0.28 multilayer flakes have a band gap of 0.25eV and exhibit thermally activated transport. Our experimental findings demonstrate that the ability to control the degree of functionalisation of graphene is instrumental to engineer different electronic properties in graphene materials.Comment: 6 pages, 5 figure

Real decoupling ghost quantization of the CGHS model for two dimensional black holes

A complete RST quantization of a CGHS model plus Strominger term is carried out. In so doing a conformal invariant theory with $\kappa=\frac{N}{12}$ is found, that is, without ghosts contribution. The physical consequences of the model are analysed and positive definite Hawking radiation is found.Comment: 14 pages, latex, no figures, marginal errors correcte

Soluble models in 2d dilaton gravity

A one-parameter class of simple models of two-dimensional dilaton gravity, which can be exactly solved including back-reaction effects, is investigated at both classical and quantum levels. This family contains the RST model as a special case, and it continuously interpolates between models having a flat (Rindler) geometry and a constant curvature metric with a non-trivial dilaton field. The processes of formation of black hole singularities from collapsing matter and Hawking evaporation are considered in detail. Various physical aspects of these geometries are discussed, including the cosmological interpretation.Comment: 15 pages, harvmac, 3 figure

Buckling of built-up columns of pultruded fiber-reinforced polymer C-sections

This paper presents the test results of an experimental investigation to evaluate the buckling behavior of built-up columns of pultruded profiles, subjected to axial compression. Specimens are assembled by using four (off the shelf) channel shaped profiles of E-glass fiber-reinforced polymer (FRP), having similar detailing to strut members in a large FRP structure that was executed in 2009 to start the restoration of the Santa Maria Paganica church in L’Aquila, Italy. This church had partially collapsed walls and no roof after the April 6, 2009, earthquake of 6.3 magnitude. A total of six columns are characterized with two different configurations for the bolted connections joining the channel sections into a built-up strut. Test results are discussed and a comparison is made with closed-form equation predictions for flexural buckling resistance, with buckling resistance values established from both eigenvalue and geometric nonlinear finite element analyses. Results show that there is a significant role played by the end loading condition, the composite action, and imperfections. Simple closed-form equations overestimate the flexural buckling strength, whereas the resistance provided by the nonlinear analysis provides a reasonably reliable numerical approach to establishing the actual buckling behavior

Model of black hole evolution

From the postulate that a black hole can be replaced by a boundary on the apparent horizon with suitable boundary conditions, an unconventional scenario for the evolution emerges. Only an insignificant fraction of energy of order $(mG)^{-1}$ is radiated out. The outgoing wave carries a very small part of the quantum mechanical information of the collapsed body, the bulk of the information remaining in the final stable black hole geometry.Comment: 9 pages, harvmac, 3 figures, minor addition

Multi-loop open string amplitudes and their field theory limit

JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0This work was supported by STFC (Grant ST/J000469/1, ‘String theory, gauge theory & duality’) and by MIUR (Italy) under contracts 2006020509 004 and 2010YJ2NYW 00