Topological Interactions in Warped Extra Dimensions

Topological interactions will be generated in theories with compact extra dimensions where fermionic chiral zero modes have different localizations. This is the case in many warped extra dimension models where the right-handed top quark is typically localized away from the left-handed one. Using deconstruction techniques, we study the topological interactions in these models. These interactions appear as trilinear and quadrilinear gauge boson couplings in low energy effective theories with three or more sites, as well as in the continuum limit. We derive the form of these interactions for various cases, including examples of Abelian, non-Abelian and product gauge groups of phenomenological interest. The topological interactions provide a window into the more fundamental aspects of these theories and could result in unique signatures at the Large Hadron Collider, some of which we explore.Comment: 40 pages, 10 figures, 2 tables; modifications in the KK parity discussion, final version at JHE

Modelling particle mass and particle number emissions during the active regeneration of diesel particulate filters

A new model has been developed to describe the size-dependent effects that are responsible for transient particle mass (PM) and particle number (PN) emissions observed during experiments of the active regeneration of Diesel Particulate Filters (DPFs). The model uses a population balance approach to describe the size of the particles entering and leaving the DPF, and accumulated within it. The population balance is coupled to a unit collector model that describes the filtration of the particles in the porous walls of the DPF and a reactor network model that is used to describe the geometry of the DPF. Two versions of the unit collector model were investigated. The original version, based on current literature, and an extended version, developed in this work, that includes terms to describe both the non-uniform regeneration of the cake and thermal expansion of the pores in the DPF. Simulations using the original unit collector model were able to provide a good description of the pressure drop and PM filtration efficiency during the loading of the DPF, but were unable to adequately describe the change in filtration efficiency during regeneration of the DPF. The introduction of the extended unit collector description enabled the model to describe both the timing of particle breakthrough and the final steady filtration efficiency of the hot regenerated DPF. Further work is required to understand better the transient behaviour of the system. In particular, we stress the importance that future experiments fully characterise the particle size distribution at both the inlet and outlet of the DPF.Cambridge Centre for Advanced Research and Education in Singapore (CARES), Royal Dutch Shell. Note: need to add PEMS4NANO (H2020) and EPSRC

Decreased dopamine activity predicts relapse in methamphetamine abusers.

Studies in methamphetamine (METH) abusers showed that the decreases in brain dopamine (DA) function might recover with protracted detoxification. However, the extent to which striatal DA function in METH predicts recovery has not been evaluated. Here we assessed whether striatal DA activity in METH abusers is associated with clinical outcomes. Brain DA D2 receptor (D2R) availability was measured with positron emission tomography and [(11)C]raclopride in 16 METH abusers, both after placebo and after challenge with 60 mg oral methylphenidate (MPH) (to measure DA release) to assess whether it predicted clinical outcomes. For this purpose, METH abusers were tested within 6 months of last METH use and then followed up for 9 months of abstinence. In parallel, 15 healthy controls were tested. METH abusers had lower D2R availability in caudate than in controls. Both METH abusers and controls showed decreased striatal D2R availability after MPH and these decreases were smaller in METH than in controls in left putamen. The six METH abusers who relapsed during the follow-up period had lower D2R availability in dorsal striatum than in controls, and had no D2R changes after MPH challenge. The 10 METH abusers who completed detoxification did not differ from controls neither in striatal D2R availability nor in MPH-induced striatal DA changes. These results provide preliminary evidence that low striatal DA function in METH abusers is associated with a greater likelihood of relapse during treatment. Detection of the extent of DA dysfunction may be helpful in predicting therapeutic outcomes

A slowly expanding disk and fast bipolar outflow from the S star π1 gruis

We study the molecular outflow of the nearby evolved S star π1 Gru. We imaged the outflow in CO J = 2-1 and dust continuum with the Submillimeter Array. The CO emission was detected over a very broad velocity width of ∼90 km s-1. Our high-resolution images show that the outflow at low velocities (≤15 km s-1) is elongated east-west and at high velocities (≥25 km s-1) is displaced north (at redshifted velocities) and south (blueshifted velocities) of center as defined by the dust continuum source. We model the spatial-kinematic structure of the low-velocity outflow as a flared disk with a central cavity of radius 200 AU and an expansion velocity of 11 km s-1, inclined by 55° to our line of sight. We attribute the high-velocity component to a bipolar outflow that emerges perpendicular to this disk with a velocity of up to ∼45 km s-1. This high-velocity outflow may play an important role in shaping the gas envelope previously ejected by the AGB star and thus produce a bipolar morphology when the object evolves into a proto-planetary nebula. © 2006. The American Astronomical Society. All rights reserved.published_or_final_versio

Ternary Syndrome Decoding with Large Weight

The Syndrome Decoding problem is at the core of many code-based cryptosystems. In this paper, we study ternary Syndrome Decoding in large weight. This problem has been introduced in the Wave signature scheme but has never been thoroughly studied. We perform an algorithmic study of this problem which results in an update of the Wave parameters. On a more fundamental level, we show that ternary Syndrome Decoding with large weight is a really harder problem than the binary Syndrome Decoding problem, which could have several applications for the design of code-based cryptosystems

Multi-Photon Signals from Composite Models at LHC

We analyze the collider signals of composite scalars that emerge in certain little Higgs models and models of vectorlike confinement. Similar to the decay of the pion into photon pairs, these scalars mainly decay through anomaly-induced interactions into electroweak gauge bosons, leading to a distinct signal with three or more photons in the final state. We study the standard model backgrounds for these signals, and find that the LHC can discover these models over a large range of parameter space with 30 fb$^{-1}$ at 14 TeV. An early discovery at the current 7 TeV run is possible in some regions of parameter space. We also discuss possibilities to measure the spin of the particles in the $\gamma \gamma$ and $Z\gamma$ decay channels.Comment: 18 pages, LaTe