The Conformal Window of deformed CFT's in the planar limit

We discuss in the planar approximation the effect of double-trace deformations on CFT's. We show that this large class of models posses a conformal window describing a non-trivial flow between two fixed points of the renormalization group, and reveal the presence of a resonance which we associate to the remnant of a dilaton pole. As the conformal window shrinks to zero measure the theory undergoes a conformal phase transition separating a symmetric from a nonsymmetric phase. The recently conjectured strongly coupled branch of non-supersymmetric, non-abelian gauge theories with a large number of flavors is analyzed in light of these results, and a model for the strong branch is proposed. Some phenomenological implications in the context of unparticle physics are also emphasized.Comment: 15 pages PRD class, 2 figures, to be published in PR

University and inter-firm R&D collaborations: propensity and intensity of cooperation in Europe

This paper investigates the determinants of firms’ decision to cooperate in R&D with universities and the intensity of the cooperation effort, in relation to the engagement in inter-firm R&D collaborations. Using novel survey data for seven EU countries between 2007 and 2009, our analysis accounts for unobservable factors influencing R&D cooperation forms and addresses the main endogeneity issues. We find that internal knowledge, appropriability conditions and incoming spillovers explain large variation in the probability and in the intensity of R&D collaborations of European firms with universities (and comparably with unaffiliated companies)

The role of electron capture decay in the precision era of Galactic cosmic-ray data

Electron capture (EC) decay relies on attachment and stripping cross-sections, that in turn, depend on the atomic number of the nucleus. We revisit the impact of EC decay in the context of the high-precision cosmic-ray fluxes measured by the AMS-02 experiment. We derive the solution of the steady-state fluxes in a 1D thin disk model including EC decay. We compare our results with relevant elemental and isotopic fluxes and evaluate the impact of this process, given the precision of recent AMS-02, ACE-CRIS, SuperTIGER, and Voyager data. We find this impact to be at the level or larger than the precision of recently collected data for several species, e.g. $_{31}$Ga and $_{33}$As, indicating that EC decay must be properly taken into account in the calculation.Comment: 8 pages, 3 figures, Proceedings for International Cosmic Ray Conference (ICRC) 202

Central equatorial Pacific zonal currents. II: The seasonal cycle and the boreal spring surface eastward surge

The seasonally averaged zonal momentum equation tendencies at 140W are studied in a high-resolution primitive equation ocean general circulation model simulation of the tropical Pacific. The model experiment, forced by climatological monthly average wind-stress, reproduces well the observed boreal springtime eastward surge of the normally westward surface flow, as well as many features of the acceleration and deceleration between the surface and 200 m between January and October. We present each of the zonal momentum equation tendency terms for the depth range 0-160 m, but our discussion focuses on the behavior of the boreal springtime near-surface flow, perhaps the most distinctive feature of the seasonal cycle. The eastward surface surge in boreal spring depends crucially on the springtime weakening of the otherwise westward tendency from tropical instability waves (TIWs). The TIW effects, together with the eastward tendency from the seasonal weakening of the easterly wind-stress, drive the eastward surface current surge. Although the \u27negative viscosity\u27 effect of the TIWs is small in the annual mean, as we have previously shown, its seasonal variation is necessary to the surface flow reversal and eastward surge in this model. A series of experiments, each with weaker TIWs than its predecessor, shows a progressive weakening and eventual absence of springtime eastward surface flow, supporting the above analysis. The seasonal zonal velocity accelerations and decelerations are small compared with the terms in the zonal momentum equation; these terms must be known to an accuracy of at least 10 cm s-1 month-1 (2-5% of the largest terms) if a meaningful budget is to be obtained. This is a strong constraint that must be planned for in future observational studies. We find that nonlinear terms are O (1) in the vertically-integrated balance as well as the local balance, in contrast with some recent observational estimates. Extrapolated velocity errors, neglected terms, data processing assumptions, and crude finite-differencing in the observational studies may account for the differences, as appeared to be the case in the annual mean balances. The model dynamical balances cannot be reproduced if the methods used to analyze observational data are applied to the model output fields. Very near-surface currents must be measured rather than extrapolated if the ocean shear is similar to that of the model flows

Critical incidents in a forensic psychiatric population: An exploratory study of motivational factors

This exploratory study examined the motivations for forensic clients’ engagement in critical incidents, specifically hostage-taking, barricades and roof-top protests. Using thematic analysis, a range of themes were identified. These included engaging in such incidents to seek deliberate isolation from others, gaining control, getting their needs meet, a need to communicate and being influenced by their peers. Selection of potential hostages appeared linked to feeling of grievance towards them. Yet the distress of a hostage, along with consideration as to the longer term consequences of their actions both for themselves and morally, appeared to reduce the risk of engagement in such incidents. The results are discussed in terms of Individualism, Self-Determination Theory of Motivation and Maslow’s Hierarchy of Human Needs

Compressing deep-quaternion neural networks with targeted regularisation

In recent years, hyper-complex deep networks (such as complex-valued and quaternion-valued neural networks - QVNNs) have received a renewed interest in the literature. They find applications in multiple fields, ranging from image reconstruction to 3D audio processing. Similar to their real-valued counterparts, quaternion neural networks require custom regularisation strategies to avoid overfitting. In addition, for many real-world applications and embedded implementations, there is the need of designing sufficiently compact networks, with few weights and neurons. However, the problem of regularising and/or sparsifying QVNNs has not been properly addressed in the literature as of now. In this study, the authors show how to address both problems by designing targeted regularisation strategies, which can minimise the number of connections and neurons of the network during training. To this end, they investigate two extensions of l1and structured regularisations to the quaternion domain. In the authors' experimental evaluation, they show that these tailored strategies significantly outperform classical (realvalued) regularisation approaches, resulting in small networks especially suitable for low-power and real-time applications

From Assessing to Conserving biodiversity. Conceptual and Practical Challenges

This open access book features essays written by philosophers, biologists, ecologists and conservation scientists facing the current biodiversity crisis. Despite increasing communication, accelerating policy and management responses, and notwithstanding improving ecosystem assessment and endangered species knowledge, conserving biodiversity continues to be more a concern than an accomplished task. Why is it so? The overexploitation of natural resources by our species is a frequently recognised factor, while the short-term economic interests of governments and stakeholders typically clash with the burdens that implementing conservation actions imply. But this is not the whole story. This book develops a different perspective on the problem by exploring the conceptual challenges and practical defiance posed by conserving biodiversity, namely: on the one hand, the difficulties in defining what biodiversity is and characterizing that “thing” to which the word ‘biodiversity’ refers to; on the other hand, the reasons why assessing biodiversity and putting in place effective conservation actions is arduous. ; Features essays that are explicitly critical of the species approach to biodiversity Presents bio-philosophical perspectives on the interaction between biodiversity’s units, levels, and scales Serves as an interdisciplinary contribution to the emergent field of biodiversity studie

Effects of surface forcing on the seasonal cycle of the eastern equatorial Pacific

The roles of zonal and meridional wind stress and of surface heat flux in the seasonal cycle of sea surface temperature (SST) are examined with a primitive equation (PE) model of the tropical Pacific Ocean. While a variety of previous numerical and observational studies have examined the seasonal cycle of SST in the eastern tropical Pacific, it is noteworthy that different mechanisms have been invoked as primary in each case and different conclusions have been reached regarding the relative importance of the various components of surface forcing. Here, we perform a series of numerical experiments in which different components of the surface forcing are eliminated and the resulting upper ocean variability is compared with that of the climatological experiment. The model used for these experiments reproduces a realistic climatological seasonal cycle, in which SST emerges as an independent quantity. We find that the different cases all produce qualitatively reasonable seasonal cycles of SST, though only the most complete model is also able to reproduce the seasonal cycle of near surface currents, tropical instability waves (TIWs), and net surface heat fluxes consistent with historical observations. These results indicate that simply reproducing a qualitatively accurate seasonal cycle of SST does not necessarily allow meaningful conclusions to be made about the relative importance of the different components of surface forcing. The results described here also suggest that a model simulation must at least reproduce all the documented near surface kinematic features of the equatorial Pacific cold tongue region reasonably well, before accurate inferences can be made from model experiments. This provides useful guidelines to current efforts to develop and evaluate more complex fully coupled air-sea models and shows that results for simple or intermediate ocean models that do not have this level of fidelity to the observations will be difficult to interpret

The deepest X-ray look at the Universe

The origin of the X-ray background, in particular at hard (2-10 keV) energies, has been a debated issue for more than 30 years. The Chandra deep fields provide the deepest look at the X-ray sky and are the best dataset to study the X-ray background. We searched the Chandra Deep Field South for X-ray sources with the aid of a dedicated wavelet-based algorithm. We are able to reconstruct the Log N-Log S source distribution in the soft (0.5-2 keV) and hard (2-10 keV) bands down to limiting fluxes of 2x10^{-17} erg s^{-1} cm^{-2} and 2x10^{-16} erg s^{-1} cm^{-2}, respectively. These are a factor ~5 deeper than previous investigations. We find that the soft relation continues along the extrapolation from higher fluxes, almost completely accounting for the soft X-ray background. On the contrary, the hard distribution shows a flattening below ~2x10^{-14} erg s^{-1} cm^{-2}. Nevertheless, we can account for >68% of the hard X-ray background, with the main uncertainty being the sky flux itself.Comment: Accepted for publication on ApJL. Two figures, requires emulateapj5 (included

Design and advancement status of the Beam Expander Testing X-ray facility (BEaTriX)

The BEaTriX (Beam Expander Testing X-ray facility) project is an X-ray apparatus under construction at INAF/OAB to generate a broad (200 x 60 mm2), uniform and low-divergent X-ray beam within a small lab (6 x 15 m2). BEaTriX will consist of an X-ray source in the focus a grazing incidence paraboloidal mirror to obtain a parallel beam, followed by a crystal monochromation system and by an asymmetrically-cut diffracting crystal to perform the beam expansion to the desired size. Once completed, BEaTriX will be used to directly perform the quality control of focusing modules of large X-ray optics such as those for the ATHENA X-ray observatory, based on either Silicon Pore Optics (baseline) or Slumped Glass Optics (alternative), and will thereby enable a direct quality control of angular resolution and effective area on a number of mirror modules in a short time, in full X-ray illumination and without being affected by the finite distance of the X-ray source. However, since the individual mirror modules for ATHENA will have an optical quality of 3-4 arcsec HEW or better, BEaTriX is required to produce a broad beam with divergence below 1-2 arcsec, and sufficient flux to quickly characterize the PSF of the module without being significantly affected by statistical uncertainties. Therefore, the optical components of BEaTriX have to be selected and/or manufactured with excellent optical properties in order to guarantee the final performance of the system. In this paper we report the final design of the facility and a detailed performance simulation.Comment: Accepted paper, pre-print version. The finally published manuscript can be downloaded from http://dx.doi.org/10.1117/12.223895