1,181 research outputs found
Di-Jet Conical Correlations Associated with Heavy Quark Jets in anti--de Sitter Space/Conformal Field Theory Correspondence
We show that far zone Mach and diffusion wake ``holograms'' produced by
supersonic strings in anti--de Sitter space/conformal field theory (AdS/CFT)
correspondence do not lead to observable conical angular correlations in the
strict supergravity limit if Cooper-Frye hadronization is
assumed. However, a special {\em nonequilibrium} ``neck'' zone near the jet is
shown to produce an apparent sonic boom azimuthal angle distribution that is
roughly independent of the heavy quark's velocity. Our results indicate that a
measurement of the dependence of the away-side correlations on the velocity of
associated identified heavy quark jets at the BNL Relativistic Heavy Ion
Collider and CERN LHC will provide a direct test of the nonperturbative
dynamics involved in the coupling between jets and the strongly-coupled
Quark-Gluon Plasma (sQGP) implied by AdS/CFT correspondence.Comment: 4 pages, 2 figures, version published in Physical Review Letter
Student conceptions of problem and project based learning in engineering education: A phenomenographic investigation
The construction of teaching roles at Aalborg university centre, 1970–1980
This paper proposes a historical analysis of the development of teaching roles at Aalborg University Centre in its first 10 years. The research highlights three processes through which the interpretation of the new ‘supervisor’ roles was constructed within the problem-oriented, project-based educational model of AUC. First, the authors show that the institutional framework for teaching roles was deliberately left open to significant interpretation from the various faculties of the university; second, the critical theoretical model that had served as a guideline for the inception of project work in Roskilde failed to make an impact in Aalborg, whereas teachers from AUC were more receptive to constructivist psychology as a theoretical framework for practice; third, through community-building and negotiation within the faculties, different interpretations of teaching roles emerged in the different disciplines. The paper closes with a reflection on the implications of these findings for the more general context of higher education
On the hitting times of quantum versus random walks
In this paper we define new Monte Carlo type classical and quantum hitting
times, and we prove several relationships among these and the already existing
Las Vegas type definitions. In particular, we show that for some marked state
the two types of hitting time are of the same order in both the classical and
the quantum case.
Further, we prove that for any reversible ergodic Markov chain , the
quantum hitting time of the quantum analogue of has the same order as the
square root of the classical hitting time of . We also investigate the
(im)possibility of achieving a gap greater than quadratic using an alternative
quantum walk.
Finally, we present new quantum algorithms for the detection and finding
problems. The complexities of both algorithms are related to the new,
potentially smaller, quantum hitting times. The detection algorithm is based on
phase estimation and is particularly simple. The finding algorithm combines a
similar phase estimation based procedure with ideas of Tulsi from his recent
theorem for the 2D grid. Extending his result, we show that for any
state-transitive Markov chain with unique marked state, the quantum hitting
time is of the same order for both the detection and finding problems
Behind the times: a brief history of motivation discourse in problem-based learning
That idea that problem-based learning (PBL) is more motivating that traditional education has been prevalent since the inception of PBL at McMaster University in the late 1960s. Evidencing this through empirical research, however, has proven to be a lot more problematic. This paper retraces how the discourse on motivation started from a laymen's conception in the early days of PBL, and slowly evolved into a field of scientific inquiry in the 1980s and 1990s. However, looking at the evolution of motivation theory over the same period, we show that motivation discourse in the burgeoning literature on motivation and PBL remained largely wedded to the laymen's approach, and failed to catch up with the new achievement-goal theory and self-determination theory approaches. This paper proceeds to analyse the explosion of studies on PBL and motivation after 2000, acknowledging efforts to move away from anecdotal accounts and provide theoretical grounding to the research. However, once again, we show that the majority of the research employed outdated motivational measures that do not fully grasp the complexity of contemporary motivation theory. The paper concludes on the observation that single-course and curriculum-wide research interventions have yielded no conclusive results on the effect of PBL on intrinsic motivation, and that future research should therefore seek to use up-to-date motivational constructs in more targeted interventions
Macromolecular crowding effects on globular protein stability
Macromolecular crowding inside cells is proposed to change many aspects of proteins compared to dilute solution. As such, it is an increasingly studied topic, both theoretically and experimentally. However, the difficulty of both theoretically modeling the intracellular milieu and manipulating its contents experimentally present roadblocks to a full picture of crowding inside cells. In vitro studies of macromolecular crowding allow us to study the effects of crowding agent identity, size, and concentration on globular protein stability in a highly controllable fashion. I used NMR-detected amide proton exchange to study the effects of poly(vinylpyrrolidone) at varying molecular weights and concentrations on the stability of chymotrypsin inhibitor 2. This residue-level study is the first to reveal both volume exclusion and weak interaction effects as contributors to protein stability in crowded conditions. I also studied the effects of a microgel crowder on the stability and dynamics of chymotrypsin inhibitor 2, displaying an upper limit to the size effect of crowding agents. This study also revealed no link between protein stability and ps-ns timescale backbone dynamics. Amide proton exchange was also used to study the effects of bovine serum albumin and lysozyme as crowding agents on chymotrypsin inhibitor 2. This is the first reported study of protein stability when subjected to crowding by another protein, and provides some important implications for the stability of proteins inside cells
Jet Quenching in Non-Conformal Holography
We use our non-conformal holographic bottom-up model for QCD described in
1012.0116 to further study the effect of the QCD trace anomaly on the energy
loss of both light and heavy quarks in a strongly coupled plasma. We compute
the nuclear modification factor for bottom and charm quarks in an
expanding plasma with Glauber initial conditions. We find that the maximum
stopping distance of light quarks in a non-conformal plasma scales with the
energy with a temperature (and energy) dependent effective power.Comment: 4 pages, 1 figure. Proceedings for Quark Matter 201
Microsatellite Markers Isolated From Cabomba Aquatica Sl (cabombaceae) From An Enriched Genomic Library
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Premise of the study: Microsatellite primers were designed for the submersed aquatic plant Cabomba aquatica s.l. (Cabombaceae) and characterized to estimate genetic diversity parameters. Methods and Results: Using a selective hybridization method, we designed and tested 30 simple sequence repeat loci using two natural populations of C. aquatica s.l., resulting in 13 amplifiable loci. Twelve loci were polymorphic, and alleles per locus ranged from two to four across the 49 C. aquatica s.l. individuals. Observed heterozygosity, expected heterozygosity, and fixation index varied from 0.0 to 1.0, 0.0 to 0.5, and -1.0 to -0.0667, respectively, for the Manaus population and from 0.0 to 1.0, 0.0 to 0.6, and -1.0 to 0.4643 for the Virua population. Conclusions: The developed markers will be used in further taxonomic and population studies within Cabomba. This set of microsatellite primers represents the first report on rapid molecular markers in the genus.311Post-Graduate program in Plant Biology of the Instituto de Biologia (UNICAMP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [PNADB 457/2010
Neural Filters for Jet Analysis
We study the efficiency of a neural-net filter and deconvolution method for
estimating jet energies and spectra in high-background reactions such as
nuclear collisions at the relativistic heavy-ion collider and the large hadron
collider. The optimal network is shown to be surprisingly close but not
identical to a linear high-pass filter. A suitably constrained deconvolution
method is shown to uncover accurately the underlying jet distribution in spite
of the broad network response. Finally, we show that possible changes of the
jet spectrum in nuclear collisions can be analyzed quantitatively, in terms of
an effective energy loss with the proposed method. {} {Dong D W and Gyulassy M
1993}{Neural filters for jet analysis}
{(LBL-31560) Physical Review E Vol~47(4) pp~2913-2922}Comment: 21 pages of Postscript, (LBL-31560
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