Borel singularities at small x

D.I.S. at small Bjorken $x$ is considered within the dipole cascade formalism. The running coupling in impact parameter space is introduced in order to parametrize effects that arise from emission of large size dipoles. This results in a new evolution equation for the dipole cascade. Strong coupling effects are analyzed after transforming the evolution equation in Borel ($b$) space. The Borel singularities of the solution are discussed first for the universal part of the dipole cascade and then for the specific process of D.I.S. at small $x$. In the latter case the leading infrared renormalon is at $b=1/\beta_0$ indicating the presence of $1/Q^2$ power corrections for the small-$x$ structure functions.Comment: 5 pages, Latex (Talk presented at DIS'97, Chicago, IL

Guided Elastic Waves in Pre-Stressed Solids for the Ultrasonic Characterization of Interfacial Zones

Towards a mechanical dynamic characterization of pre-stressed layered solids and a non-destructive ultrasonic evaluation of their interfacial bonds, it is necessary to examine the propagation of elastic interfacial waves along planar boundaries between finitely pre-strained incompressible solids. The effect of pre-stress on the propagation of Stoneley waves was first examined in [1,2] for two half-spaces of the same incompressible neo-hookean material subjected to different homogeneous pre-strains of common principal axes. In [3] propagation of Stoneley waves along a common principal axis of pre-strain of the two half-spaces which were taken as different incompressible materials having arbitrary strain energy functions was considered. The effect of pre-stress on Rayleigh waves was first studied in [4]. In [5] results were obtained for more general pre-stress conditions on an incompressible half-space of arbitrary strain energy function

An Outline of a Progressive Resolution to the Euro-area Sovereign Debt Overhang: How a Five year Suspension of the Debt Burden Could Overthrow Austerity

The present study puts forward a plan for solving the sovereign debt crisis in the euro area (EA) in line with the interests of the working classes and the social majority. Our main strategy is for the European Central Bank (ECB) to acquire a significant part of the outstanding sovereign debt (at market prices) of the countries in the EA and convert it to zero-coupon bonds. No transfers will take place between individual states; taxpayers in any EA country will not be involved in the debt restructuring of any foreign eurozone country. Debt will not be forgiven: individual states will agree to buy it back from the ECB in the future when the ratio of sovereign debt to GDP has fallen to 20 percent. The sterilization costs for the ECB are manageable. This model of an unconventional monetary intervention would give progressive governments in the EA the necessary basis for developing social and welfare policies to the benefit of the working classes. It would reverse present-day policy priorities and replace the neoliberal agenda with a program of social and economic reconstruction, with the elites paying for the crisis. The perspective taken here favors social justice and coherence, having as its priority the social needs and the interests of the working majority

Extracting the Groupwise Core Structural Connectivity Network: Bridging Statistical and Graph-Theoretical Approaches

Finding the common structural brain connectivity network for a given population is an open problem, crucial for current neuro-science. Recent evidence suggests there's a tightly connected network shared between humans. Obtaining this network will, among many advantages , allow us to focus cognitive and clinical analyses on common connections, thus increasing their statistical power. In turn, knowledge about the common network will facilitate novel analyses to understand the structure-function relationship in the brain. In this work, we present a new algorithm for computing the core structural connectivity network of a subject sample combining graph theory and statistics. Our algorithm works in accordance with novel evidence on brain topology. We analyze the problem theoretically and prove its complexity. Using 309 subjects, we show its advantages when used as a feature selection for connectivity analysis on populations, outperforming the current approaches

AT&T vs Verizon: Mining Twitter for Customer Satisfaction towards North American Mobile Operators

The North American Telecommunications sector is one of the leading mobile broadband sectors worldwide, representing increasingly important revenue opportunities for mobile operators. Taking into consideration that the market is being saturated and revenue from new subscriptions is increasingly deteriorating, mobile carriers tend to focus on customer service and high levels of customer satisfaction in order to retain customers and maintain a low churn rate. In this context, it is a matter of critical importance to be able to measure the overall customer satisfaction level, by explicitly or implicitly mining the public opinion towards this end. In this paper, we argue that online social media can be exploited as a proxy to infer customer satisfaction through the utilization of automated, machine-learning based sentiment analysis techniques. Our work focuses on the two leading mobile broadband carriers located in the broader North American area, AT&T and Verizon, by analysing tweets fetched during a 15-day period within February 2013, to assess relative customer satisfaction degrees. The validity of our approach is justified through comparison against surveys conducted during 2012 from Forrester and Vocalabs in terms of customer satisfaction on the overall brand - usage experience

SRF role as a mechano-transductor in response to exercise in cancer cachexia

Introduction: Recent studies showed that physical activity increased survival in cancer patient and animal models of cancer cachexia. The underlying mechanisms, however, are still largely unknown. Methods: To identify signalling pathways involved in exercise-dependent maintenance of muscle mass and function in cachexia, we investigated the role of serum response factor (SRF)—a transcription factor playing a pivotal a role in muscular growth, differentiation and regeneration—in C26-bearing mice in the absence or presence of voluntary exercise (wheel running). Results: SRF levels are decreased at protein level in cachexia. Consistently, a decrease in the expression of SRF target genes such as MyoD and SK-actin occurs in C26-bearing mice, suggesting a decrease of SRF transcriptional activity. These tumour effects were counteracted by wheel running and associated to the rescue of muscle mass and function. However, a minimum amount of exercise (2 km/day) is necessary to keep SRF levels elevated in cachexia over a threshold which is necessary to exert beneficial effects. SRF levels inversely correlate with wasting in mice, suggesting that SRF play a role in maintaining body mass (mostly accounted for by muscle mass). We also observe the recruitment of nuclei within the muscle fibres in response to exercise, which could contribute to muscle homeostasis and is consistent with the previously observed opposite effects of tumour and exercise on MyoD and Pax7 expression. Conclusions: Our results suggest that physical activity rescues SRF expression as well as its transcriptional activity, highlighting the importance of genetic activation induced by skeletal muscle activity for muscle rescue and homeostasis. These effects could be extended to the fibre microenvironment, including myogenic stem cell activity