The LHCb Upgrade

The LHCb detector has been designed to study CP violation and other rare phenomena in B-meson decays up to a luminosity of $\sim 5.10^{32}\rm cm^{-2}s^{-1}$. This paper will describe what is limiting LHCb to exploit the much higher luminosities available at the LHC, and what are the baseline modifications which will remedy these limitations. The aim of SuperLHCb is to increase the yields in hadronic B-decay channels by about a factor twenty compared to LHCb, while for channels with leptons in the final state a factor ten increase in statistics is envisaged.Comment: Flavor Physics & CP Violation Conference, Bled, 200

Lyman Alpha Emitting Galaxies as a Probe of Reionization

The Epoch of Reionization (EoR) represents a milestone in the evolution of our Universe. Star-forming galaxies that existed during the EoR likely emitted a significant fraction (~5-40%) of their bolometric luminosity as Lyman Alpha (Lya) line emission. However, neutral intergalactic gas that existed during the EoR was opaque to Lya emission that escaped from galaxies during this epoch, which makes it difficult to observe. The neutral intergalactic medium (IGM) may thus reveal itself by suppressing the Lya flux from background galaxies. Interestingly, a `sudden' reduction in the observed Lya flux has now been observed in galaxies at z >6. This review contains a detailed summary of Lya radiative processes: I describe (i) the main Lya emission processes, including collisional-excitation & recombination (and derive the famous factor `0.68'), and (ii) basic radiative transfer concepts, including e.g. partially coherent scattering, frequency diffusion, resonant versus wing scattering, optically thick versus 'extremely' optically thick (static/outflowing/collapsing) media, and multiphase media. Following this review, I derive expressions for the Gunn-Peterson optical depth of the IGM during (inhomogeneous) reionization and post-reionization. I then describe why current observations appear to require a very rapid evolution of volume-averaged neutral fraction of hydrogen in the context of realistic inhomogeneous reionization models, and discuss uncertainties in this interpretation. Finally, I describe how existing & futures surveys and instruments can help reduce these uncertainties, and allow us to fully exploit Lya emitting galaxies as a probe of the EoR.Comment: 27 pages, 19 figures. Invited review submitted to PASA following revision based on referee report. Added some references, fixed Fig~

Expert judgment versus public opinion - evidence from the Eurovision Song Contest

For centuries, there have been discussions as to whether only experts can judge the quality of cultural output, or whether the taste of the public also has merit. This paper tries to resolve that question empirically, using national finals of the Eurovision Song Contest. We show that experts are better judges of quality: the outcome of finals judged by experts is less sensitive to factors unrelated to quality than the outcome of finals judged by public opinion. Yet, experts are not perfect: their judgment does still depend on such factors. This is also the case in the European finals of the contest.

GOOD AND BAD EQUILIBRIA WITH THE INFORMAL SECTOR

We examine whether an economy can have a bad (small or no formal sector, high taxes) as well as a good (small or no informal sector, low taxes) equilibrium. When the government maximizes instantaneous formal sector welfare, this can occur if the elasticity of average to marginal cost for the public good is less than one. More regard for the informal sector leads to a worse equilibrium, and a higher prevalence of multiple equilibria.

Computation of Bhat's OMIT maps with different coefficients

The OMIT electron-density-map calculation is very effective in discovering errors in a macromolecular structure determination. A Fortran program called OMIT has been written to calculate such maps and an investigation has been carried out into which coefficients for the map calculation produce the best OMIT maps. Testing of the program on Savinase showed that the best overall results were obtained when |Fo| without figure of merit was used. In regions where the map is incorrect, the most interesting OMIT maps are produced when only the figure of merit, or modified SIGMAA coefficients, are used as the initial map amplitude coefficients. Thus, these tests suggest that such OMIT maps are particularly useful to reconstruct the macromolecular model in the grossly incorrect regions of the model.

Crystal nucleation of colloidal hard dumbbells

Using computer simulations we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the aperiodic crystal phase using the kinetic prefactor as determined from event driven molecular dynamics simulations. We find good agreement with the nucleation rates determined from spontaneous nucleation events observed in event driven molecular dynamics simulations within error bars of one order of magnitude. We study the effect of aspect ratio of the dumbbells on the nucleation of plastic and aperiodic crystal phases and we also determine the structure of the critical nuclei. Moreover, we find that the nucleation of the aligned CP1 crystal phase is strongly suppressed by a high free energy barrier at low supersaturations and slow dynamics at high supersaturations.Comment: Accepted by J. Chem. Phy

Polyamide-rubber blends: micrscopic studies of the deformation zone

The morphology of injection moulded samples of polyamide—polybutadiene blends (85.15) with an average particle size of 0.3 μm was studied. The samples were fractured in a notched tensile test at crosshead speeds of 10−4 and 1 ms −1 and the structure of the deformation zone was studied using various techniques: polarized light microscopy, scanning electron microscopy, transmission electron microscopy on stained cut samples and carbon replicas, and selected area electron diffraction transmission electron microscopy. The deformation zone of samples tested at 10−4 ms−1 was found to consist of two layers. Far from the fracture surface a layer was observed with more or less round cavities and with cavities in the rubber particles, while near the fracture surface a layer with strongly deformed cavities (length/diameter ratio of 5–10) could be seen. In the samples tested at 1 ms−1 the deformation zone was found to have three layers. In addition to the two previous layers an extra layer next to the fracture plane was found. This layer was 2–3 μm thick with round rubber particles and no orientation of the matrix material. This indicates that, at the high deformation speed of the test, relaxation in the melt took place, suggesting that the material around the crack tip was molten during fracture.\u

Samaritan vs rotten kid: Another look

We set up a two-stage game with sequential moves by one altruistic agent and n selfish agents. The rotten kid theorem states that the altruist can only reach her first best when the selfish agents move before the altruist. The Samaritan's dilemma, on the other hand, states that the altruist can only reach her first best when she moves before the selfish agents. We find that in general, the altruist can reach her first best when she moves first, if and only if a selfish agent's action marginally only affects his own payoff. The altruist can reach her first best when she moves last if and only if there is just one commodity involved. When the altruist cannot reach her first best when she moves last, the outcome is not Pareto efficient either.

Phase Separation and Self-Assembly in a Fluid of Mickey Mouse Particles

Recent developments in the synthesis of colloidal particles allow for control over shape and inter-particle interaction. One example, among others, is the so-called "Mickey Mouse" (MM) particle for which the self-assembly properties have been previously studied yielding a stable cluster phase together with elongated, tube-like structures. Here, we investigate under which conditions a fluid of Mickey Mouse particles can yield phase separation and how the self-assembly behaviour affects the gas-liquid coexistence. We vary the distance between the repulsive and the attractive lobes (bond length), and the interaction range, and follow the evolution of the gas-liquid (GL) coexistence curve. We find that upon increasing the bond length distance the binodal line shifts to lower temperatures, and that the interaction range controls the transition between phase separation and self-assembly of clusters. Upon further reduction of the interaction range and temperature, the clusters assume an increasingly ordered tube-like shape, ultimately matching the one previously reported in literature. These results are of interest when designing particle shape and particle-particle interaction for self-assembly processes

Motor action and emotional memory

Can simple motor actions affect how efficiently people retrieve emotional memories, and influence what they choose to remember? In Experiment 1, participants were prompted to retell autobiographical memories with either positive or negative valence, while moving marbles either upward or downward. They retrieved memories faster when the direction of movement was congruent with the valence of the memory (upward for positive, downward for negative memories). Given neutral-valence prompts in Experiment 2, participants retrieved more positive memories when instructed to move marbles up, and more negative memories when instructed to move them down, demonstrating a causal link from motion to emotion. Results suggest that positive and negative life experiences are implicitly associated with schematic representations of upward and downward motion, consistent with theories of metaphorical mental representation. Beyond influencing the efficiency of memory retrieval, the direction of irrelevant, repetitive motor actions can also partly determine the emotional content of the memories people retrieve: moving marbles upward (an ostensibly meaningless action) can cause people to think more positive thoughts