Extrahepatic Biliary Schwannomas: A Case Report

Benign schwannomas arise in neural crest-derived Schwann cells. They can occur almost anywhere in the body, but their most common locations are the central nervous system, extremities, neck, mediastinum, and retroperitoneum. Schwannomas occurring in the biliary tract are extremely rare and mostly present with obstructive jaundice. We recently experienced a case of extrahepatic biliary schwannomas in a 64-yr-old female patient who presented with intra- and extrahepatic bile duct and gallbladder stones during a screening program. To the best of our knowledge, extrahepatic biliary schwannomas associated with bile duct stones have not been reported previously in the literature

Data assimilation in a system with two scales-combining two initialization techniques

11 pages, 11 figures, 1 tableFull-text version available Open Access at: http://clivar.iim.csic.es/?q=es/node/319An ensemble Kalman filter (EnKF) is used to assimilate data onto a non-linear chaotic model, coupling two kinds of variables. The first kind of variables of the system is characterized as large amplitude, slow, large scale, distributed in eight equally spaced locations around a circle. The second kind of variables are small amplitude, fast, and short scale, distributed in 256 equally spaced locations. Synthetic observations are obtained from the model and the observational error is proportional to their respective amplitudes. The performance of the EnKF is affected by differences in the spatial correlation scales of the variables being assimilated. This method allows the simultaneous assimilation of all the variables. The ensemble filter also allows assimilating only the large-scale variables, letting the small-scale variables to freely evolve. Assimilation of the large-scale variables together with a few small-scale variables significantly degrades the filter. These results are explained by the spurious correlations that arise from the sampled ensemble covariances. An alternative approach is to combine two different initialization techniques for the slow and fast variables. Here, the fast variables are initialized by restraining the evolution of the ensemble members, using a Newtonian relaxation toward the observed fast variables. Then, the usual ensemble analysis is used to assimilate the large-scale observationsThis study is supported by the Spanish National Science Program under contracts ESP2005–06823-C05 and ESP2007–65667-C04Peer reviewe

Vacuum structure for scalar cosmological perturbations in Modified Gravity Models

We have found for the general class of Modified Gravity Models f(R,G) a new instability which can arise in vacuum for the scalar modes of the cosmological perturbations if the background is not de Sitter. In particular, the short-wavelength modes, if stable, in general have a group velocity which depends linearly in k, the wave number. Therefore these modes will be in general superluminal. We have also discussed the condition for which in general these scalar modes will be ghost-like. There is a subclass of these models, defined out of properties of the function f(R,G) and to which the f(R) and f(G) models belong, which however does not have this feature.Comment: 17 pages, 1 figure, uses RevTeX, references adde

Measurement of Dijet Azimuthal Decorrelations at Central Rapidities in pp-bar Collisions at sqrt(s)=1.96 TeV

Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in pp-bar collisions at a center-of-mass energy sqrt(s)=1.96 TeV. The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb-1. Azimuthal correlations are stronger at larger transverse momenta. These are well-described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where soft effects are significant.Comment: 6 pages, 3 Figures submitted to Phys. Rev. Let

Search for doubly charged Higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in p(p)over-bar collisions at root s=1.96 TeV

A search for pair production of doubly charged Higgs bosons in the process p (p) over bar -->H++H---->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of roots=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H-L(+/-+/-))>118.4 GeV/c(2) and M(H-R(+/-+/-))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs

The Internet and the Consumer: Countervailing Power Revisited

The Internet is a tool with the potential to enable consumers to effectively participate in collective bargaining in the marketplace. The purpose of this paper is to address the viability of the concept of countervailing power in the Internet era. First, some theoretical perspectives on how on-line consumer networks have the potential to be a new source of countervailing power are introduced. Next, the potential for consumer countervailing power in the Internet era is discussed. A case study that illustrates the viability of the propositions is then presented. Finally, implications and limitations of the paper are briefly discussed: if the potential for countervailing power can be established, then the circumstances under which collective bargaining would occur and the determinants of its outcome would be of vital interest to consumer economists and policy makers.Electronic Commerce, Internet, Countervailing Power, Consumer, Consumer Behaviour,

Predicting the Drivers of the Intention to Use Mobile Learning in South Korea

This study empirically analyzed a survey conducted on South Korean undergraduate students to determine the factors that influence their decision to adopt mobile learning. The consumer typology approach was applied based on their mobile technology readiness, and identified three distinct consumer groups: critical adopters, pro-technology, and ambivalent. Critical adopters were the largest of the three groups, indicating that a significant portion of university students in South Korea might be critical adopters of mobile learning. Compatibility and observability positively influenced the intention to use mobile learning in all consumer groups. In the critical adopter and ambivalent groups, mobile learning resistance had the greatest effect on the intention to use mobile learning, while in the pro-technology group mobile learning self-efficacy had the greatest effect on this intention. Results identified significant differences across consumer groups in the antecedents and consequences of the intention to use mobile learning

The mental accounting of time

This paper examines the ways in which time is perceived and tracked. We investigate whether people create mental accounts for time like they do for money, how time is allotted to these accounts and if time is valued differently according to the account to which it is assigned. Across five studies, we find evidence that people create mental accounts for time and attempt to balance their time across work and non-work activities.Mental accounts

Predicting the Drivers of the Intention to Use Mobile Learning in South Korea

This study empirically analyzed a survey conducted on South Korean undergraduate students to determine the factors that influence their decision to adopt mobile learning. The consumer typology approach was applied based on their mobile technology readiness, and identified three distinct consumer groups: critical adopters, pro-technology, and ambivalent. Critical adopters were the largest of the three groups, indicating that a significant portion of university students in South Korea might be critical adopters of mobile learning. Compatibility and observability positively influenced the intention to use mobile learning in all consumer groups. In the critical adopter and ambivalent groups, mobile learning resistance had the greatest effect on the intention to use mobile learning, while in the pro-technology group mobile learning self-efficacy had the greatest effect on this intention. Results identified significant differences across consumer groups in the antecedents and consequences of the intention to use mobile learning