Strong coupling in extended Horava-Lifshitz gravity

An extension of Horava-Lifshitz gravity was recently proposed in order to address the pathological behavior of the scalar mode all previous versions of the theory exhibit. We show that even in this new extension the strong coupling persists, casting doubts on whether such a model can constitute an interesting alternative to general relativity (GR).Comment: 4 pages; v2: minor changes and references added; v3: clarification regarding the strong coupling scale added; v4: version accepted for publication in PLB, addresses issues raised in arXiv:0912.055

The Jacobson radical for analytic crossed products

We characterise the (Jacobson) radical of the analytic crossed product of C_0(X) by the non-negative integers (Z_+), answering a question first raised by Arveson and Josephson in 1969. In fact, we characterise the radical of analytic crossed products of C_0(X) by (Z_+)^d. The radical consists of all elements whose `Fourier coefficients' vanish on the recurrent points of the dynamical system (and the first one is zero). The multi-dimensional version requires a variation of the notion of recurrence, taking into account the various degrees of freedom.Comment: 17 pages; AMS-LaTeX; minor correction

Lateral meniscal cyst presenting as Medial Compartment Knee Swelling: A case report and literature review

AbstractINTRODUCTIONMeniscal cysts are relatively uncommon orthopaedic lesions usually arising from the meniscus. They present as clinically palpable masses and dull pain.PRESENTATION OF CASEWe report on a 33-year-old male patient who presented clinically with a medial knee swelling that arose from a lateral meniscal cyst.DISCUSSIONNo similar cases were cited in the literature. The cyst was removed surgically with a good result obtained and no recurrence after 12 months. Typically, a clinically palpable mass corresponds to a meniscal cyst arising from the ipsilateral meniscus.CONCLUSIONMagnetic resonance imaging is vital to exclude such anomalies prior to surgical intervention

Culture Changing: A Development and Empirical Exploration in the Greek Tax Administration

AbstractThe purpose of this study is to empirically explore for developing a cultural change intervention for an Empowered Organization Audit in Greek Tax Administration. By using modern theoretical and empirical approaches we examine the Empowering Organization Audit as directly affected by the prevailing management culture. This paper surveys issues related to Empowerment functions, by the following best practices to develop the full employee potential to their employees. Organizational Culture, Clear Vision, Wording the Values, Teamwork, Role of Management-Leadership, Transition the Power and Responsibility, Sharing information, Continuing Education and Training, Rewards Systems, Setting objectives. The findings of this study offer methods and procedures that can contribute a basis line for developing a culture change intervention for Empowering Organization Audit in the Greek Tax Administration and aims to changing employee's behavior

Local Competition and Stochasticity for Adversarial Robustness in Deep Learning

This work addresses adversarial robustness in deep learning by considering deep networks with stochastic local winner-takes-all (LWTA) activations. This type of network units result in sparse representations from each model layer, as the units are organized in blocks where only one unit generates a non-zero output. The main operating principle of the introduced units lies on stochastic arguments, as the network performs posterior sampling over competing units to select the winner. We combine these LWTA arguments with tools from the field of Bayesian non-parametrics, specifically the stick-breaking construction of the Indian Buffet Process, to allow for inferring the sub-part of each layer that is essential for modeling the data at hand. Then, inference is performed by means of stochastic variational Bayes. We perform a thorough experimental evaluation of our model using benchmark datasets. As we show, our method achieves high robustness to adversarial perturbations, with state-of-the-art performance in powerful adversarial attack schemes.Comment: Accepted AISTATS 2021. arXiv admin note: text overlap with arXiv:2006.1062

Cardiorespiratory Fitness, Metabolic Risk, and Inflammation in Children

The aim of this study was to investigate the independent associations among cardiorespiratory fitness, metabolic syndrome (MetS), and C-reactive protein (CRP) in children. The sample consisted of 112 children (11.4  ±  0.4 years). Data was obtained for children's anthropometry, cardiorespiratory fitness, MetS components, and CRP levels. MetS was defined using criteria analogous to the Adult Treatment Panel III definition. A MetS risk score was also computed. Prevalence of the MetS was 5.4%, without gender differences. Subjects with low fitness showed significantly higher MetS risk (P < 0.001) and CRP (P < 0.007), compared to the high-fitness pupils. However, differences in MetS risk, and CRP between fitness groups decreased when adjusted for waist circumference. These data indicate that the mechanisms linking cardiorespiratory fitness, MetS risk and inflammation in children are extensively affected by obesity. Intervention strategies aiming at reducing obesity and improving cardiorespiratory fitness in childhood might contribute to the prevention of the MetS in adulthood

Codimension-2 brane inflation

We consider a probe codimension-2 brane inflation scenario in a warped six-dimensional flux compactification. Our background model is Salam-Sezgin gauged supergravity with codimension-2 brane sources, which preserve N=1 supersymmetry. The model has a modulus, which is stabilised by means of a cap regularisation of the codimension-2 singularities, with appropriate dilaton potentials on the ring interface of the caps with the bulk. We discuss the cosmological evolution of the world-volume of a probe codimension-2 brane when it moves along the radial direction of the internal space. In order to have slow-roll inflation, one needs the warping of the internal space to be weak, in contrast to the recent string inflation constructions with strong warping. We discuss the parameter range that the inflation is in agreement with the observationally inferred parameters and which furthermore is consistent with the probe brane approximation. We provide arguments pointing that the probe brane approximation is a good assumption if the probe brane is not exactly conical and show with a multibrane solution that the mild warping needed for a slow-roll inflation is not spoiled by the probe brane.Comment: 38 pages, 1 figure, Journal version in Phys. Rev.

How Damage Diversification Can Reduce Systemic Risk

We consider the problem of risk diversification in complex networks. Nodes represent e.g. financial actors, whereas weighted links represent e.g. financial obligations (credits/debts). Each node has a risk to fail because of losses resulting from defaulting neighbors, which may lead to large failure cascades. Classical risk diversification strategies usually neglect network effects and therefore suggest that risk can be reduced if possible losses (i.e., exposures) are split among many neighbors (exposure diversification, ED). But from a complex networks perspective diversification implies higher connectivity of the system as a whole which can also lead to increasing failure risk of a node. To cope with this, we propose a different strategy (damage diversification, DD), i.e. the diversification of losses that are imposed on neighboring nodes as opposed to losses incurred by the node itself. Here, we quantify the potential of DD to reduce systemic risk in comparison to ED. For this, we develop a branching process approximation that we generalize to weighted networks with (almost) arbitrary degree and weight distributions. This allows us to identify systemically relevant nodes in a network even if their directed weights differ strongly. On the macro level, we provide an analytical expression for the average cascade size, to quantify systemic risk. Furthermore, on the meso level we calculate failure probabilities of nodes conditional on their system relevance