346 research outputs found
Lifelong Learning for Information Systems Professionals
A quarter century ago, Toffler (1970) speculated that the rate at which changes took place was increasing at an ever-faster pace. He surmised that this was creating a more complex environment with greater uncertainty for individuals and organizations. Since his prediction, the business world has surely experienced immense changes that have seemed to occur with increasing frequency. Product life cycles have been drastically shortened in many industries. Globalization of the marketplace has taken place in a very short time span. Fluctuating prices for raw materials and energy, currency volatility, industry deregulation, and a host of other transformations have all contributed to an increasingly complex competitive environment. These changes havehad a major impact on the practice of information systems and on the careers of professionals. We will argue in this paper that the changes necessitate a complete reengineering of information systems curricula and teaching method
Holographic Renormalization for z=2 Lifshitz Space-Times from AdS
Lifshitz space-times with critical exponent z=2 can be obtained by
dimensional reduction of Schroedinger space-times with critical exponent z=0.
The latter space-times are asymptotically AdS solutions of AdS gravity coupled
to an axion-dilaton system and can be uplifted to solutions of type IIB
supergravity. This basic observation is used to perform holographic
renormalization for 4-dimensional asymptotically z=2 locally Lifshitz
space-times by Scherk-Schwarz dimensional reduction of the corresponding
problem of holographic renormalization for 5-dimensional asymptotically locally
AdS space-times coupled to an axion-dilaton system. We can thus define and
characterize a 4-dimensional asymptotically locally z=2 Lifshitz space-time in
terms of 5-dimensional AdS boundary data. In this setup the 4-dimensional
structure of the Fefferman-Graham expansion and the structure of the
counterterm action, including the scale anomaly, will be discussed. We find
that for asymptotically locally z=2 Lifshitz space-times obtained in this way
there are two anomalies each with their own associated nonzero central charge.
Both anomalies follow from the Scherk--Schwarz dimensional reduction of the
5-dimensional conformal anomaly of AdS gravity coupled to an axion-dilaton
system. Together they make up an action that is of the Horava-Lifshitz type
with nonzero potential term for z=2 conformal gravity.Comment: 32 pages, v2: modified discussion of the central charge
InfluĂŞncia da localização da semente na porcentagem de Ăłleo e no teor de umidade em capĂtulos de girassol
Geometry of Schroedinger Space-Times II: Particle and Field Probes of the Causal Structure
We continue our study of the global properties of the z=2 Schroedinger
space-time. In particular, we provide a codimension 2 isometric embedding which
naturally gives rise to the previously introduced global coordinates.
Furthermore, we study the causal structure by probing the space-time with point
particles as well as with scalar fields. We show that, even though there is no
global time function in the technical sense (Schroedinger space-time being
non-distinguishing), the time coordinate of the global Schroedinger coordinate
system is, in a precise way, the closest one can get to having such a time
function. In spite of this and the corresponding strongly Galilean and almost
pathological causal structure of this space-time, it is nevertheless possible
to define a Hilbert space of normalisable scalar modes with a well-defined
time-evolution. We also discuss how the Galilean causal structure is reflected
and encoded in the scalar Wightman functions and the bulk-to-bulk propagator.Comment: 32 page
T- and B-cell responses to multivalent prime-boost DNA and viral vectored vaccine combinations against hepatitis C virus in non-human primates.
Immune responses against multiple epitopes are required for the prevention of hepatitis C virus (HCV) infection, and the progression to phase I trials of candidates may be guided by comparative immunogenicity studies in non-human primates. Four vectors, DNA, SFV, human serotype 5 adenovirus (HuAd5) and Modified Vaccinia Ankara (MVA) poxvirus, all expressing hepatitis C virus Core, E1, E2 and NS3, were combined in three prime-boost regimen, and their ability to elicit immune responses against HCV antigens in rhesus macaques was explored and compared. All combinations induced specific T-cell immune responses, including high IFN-Îł production. The group immunized with the SFV+MVA regimen elicited higher E2-specific responses as compared with the two other modalities, while animals receiving HuAd5 injections elicited lower IL-4 responses as compared with those receiving MVA. The IFN-Îł responses to NS3 were remarkably similar between groups. Only the adenovirus induced envelope-specific antibody responses, but these failed to show neutralizing activity. Therefore, the two novel regimens failed to induce superior responses as compared with already existing HCV vaccine candidates. Differences were found in response to envelope proteins, but the relevance of these remain uncertain given the surprisingly poor correlation with immunogenicity data in chimpanzees, underlining the difficulty to predict efficacy from immunology studies.This work was supported by European Union contract QLK2-CT-1999-
00356, by the Biomedical Primate Research Centre, The Netherlands, and by the Swedish
Research Council. We are grateful to Alexander van den Berg for technical assistance with the
ICS, to our colleagues from Animal Science Department for technical assistance and expert care
of the macaques, to the participants of the European HCVacc Cluster who provided help and
support, and to Thomas Darton (Oxford Vaccine Group, UK) for input and advice on the
manuscript. Christine Rollier is an Oxford Martin fellow and a Jenner Insitute Investigator.This is the author accepted manuscript. The final version is available from Nature Publishing Group at https://doi.org/10.1038/gt.2016.55
Geometry of Schroedinger Space-Times, Global Coordinates, and Harmonic Trapping
We study various geometrical aspects of Schroedinger space-times with
dynamical exponent z>1 and compare them with the properties of AdS (z=1). The
Schroedinger metrics are singular for 1<z<2 while the usual Poincare
coordinates are incomplete for z \geq 2. For z=2 we obtain a global coordinate
system and we explain the relations among its geodesic completeness, the choice
of global time, and the harmonic trapping of non-relativistic CFTs. For z>2, we
show that the Schroedinger space-times admit no global timelike Killing
vectors.Comment: 15 pages, v2: some comments and references adde
Schr\"odinger Manifolds
This article propounds, in the wake of influential work of Fefferman and
Graham about Poincar\'e extensions of conformal structures, a definition of a
(Poincar\'e-)Schr\"odinger manifold whose boundary is endowed with a conformal
Bargmann structure above a non-relativistic Newton-Cartan spacetime. Examples
of such manifolds are worked out in terms of homogeneous spaces of the
Schr\"odinger group in any spatial dimension, and their global topology is
carefully analyzed. These archetypes of Schr\"odinger manifolds carry a Lorentz
structure together with a preferred null Killing vector field; they are shown
to admit the Schr\"odinger group as their maximal group of isometries. The
relationship to similar objects arising in the non-relativisitc AdS/CFT
correspondence is discussed and clarified.Comment: 42 pages, 1 figure, published version: J. Phys. A: Math. Theor. 45
(2012) 395203 (24pp
Heterologous Replacement of the Supposed Host Determining Region of Avihepadnaviruses: High In Vivo Infectivity Despite Low Infectivity for Hepatocytes
Hepadnaviruses, including hepatitis B virus (HBV), a highly relevant human pathogen, are small enveloped DNA viruses that replicate via reverse transcription. All hepadnaviruses display a narrow tissue and host tropism. For HBV, this restricts efficient experimental in vivo infection to chimpanzees. While the cellular factors mediating infection are largely unknown, the large viral envelope protein (L) plays a pivotal role for infectivity. Furthermore, certain segments of the PreS domain of L from duck HBV (DHBV) enhanced infectivity for cultured duck hepatocytes of pseudotyped heron HBV (HHBV), a virus unable to infect ducks in vivo. This implied a crucial role for the PreS sequence from amino acid 22 to 90 in the duck tropism of DHBV. Reasoning that reciprocal replacements would reduce infectivity for ducks, we generated spreading-competent chimeric DHBVs with L proteins in which segments 22–90 (Du-He4) or its subsegments 22–37 and 37–90 (Du-He2, Du-He3) are derived from HHBV. Infectivity for duck hepatocytes of Du-He4 and Du-He3, though not Du-He2, was indeed clearly reduced compared to wild-type DHBV. Surprisingly, however, in ducks even Du-He4 caused high-titered, persistent, horizontally and vertically transmissable infections, with kinetics of viral spread similar to those of DHBV when inoculated at doses of 108 viral genome equivalents (vge) per animal. Low-dose infections down to 300 vge per duck did not reveal a significant reduction in specific infectivity of the chimera. Hence, sequence alterations in PreS that limited infectivity in vitro did not do so in vivo. These data reveal a much more complex correlation between PreS sequence and host specificity than might have been anticipated; more generally, they question the value of cultured hepatocytes for reliably predicting in vivo infectivity of avian and, by inference, mammalian hepadnaviruses, with potential implications for the risk assessment of vaccine and drug resistant HBV variants
Gene expression profiling reveals insights into infant immunological and febrile responses to group B meningococcal vaccine
Neisseria meningitidis is a major cause of meningitis and septicaemia. A MenB vaccine (4CMenB) was licensed by the European Medicines Agency in January 2013. Here we describe the blood transcriptome and proteome following infant immunisations with or without concomitant 4CMenB, to gain insight into the molecular mechanisms underlying post-vaccination reactogenicity and immunogenicity. Infants were randomised to receive control immunisations (PCV13 and DTaP-IPV-Hib) with or without 4CMenB at 2 and 4 months of age. Blood gene expression and plasma proteins were measured prior to, then 4 h, 24 h, 3 days or 7 days post-vaccination. 4CMenB vaccination was associated with increased expression of ENTPD7 and increased concentrations of 4 plasma proteins: CRP, G-CSF, IL-1RA and IL-6. Post-vaccination fever was associated with increased expression of SELL, involved in neutrophil recruitment. A murine model dissecting the vaccine components found the concomitant regimen to be associated with increased gene perturbation compared with 4CMenB vaccine alone with enhancement of pathways such as interleukin-3, -5 and GM-CSF signalling. Finally, we present transcriptomic profiles predictive of immunological and febrile responses following 4CMenB vaccine
- …