City rats: From rat behaviour to human spatial cognition in urban environments

The structure and shape of an urban environment influence our ability to find our way about in the city^1-2^. Indeed, urban designers who face the challenge of planning environments that facilitate wayfinding^3^, have a consequent need to understand the relations between the urban environment and spatial cognition^4^. Previous studies have suggested that certain qualities of city elements, such as a distinct contrast with the background (e.g. The Eiffel Tower in Paris), or a clear morphology (e.g. the grid layout of Manhattan's streets) affect spatial behaviour and cognition^1,5-7^. However, only a few empirical studies have examined the relations between the urban environment and spatial cognition. Here we suggest that testing rats in experimental environments that simulate certain facets of urban environment can provide an insight into human spatial behaviour in urban environments with a similar layout. Specifically, we simulated two city layouts: (1) a grid street layout such as that of Manhattan; and (2) an irregular street layout such as that of Jerusalem. We found that the rats that were tested in the grid layout covered more ground and visited more locations, compared with the restricted movement demonstrated by the rats tested in the irregular layout. This finding in rats is in accordance with previous findings that urban grids conduce to high movement flow throughout the city, compared to low movement flow in irregular urban layouts^8-9^. Previous studies revealed that the spatial behaviour of rats and humans is controlled by the same underlying mechanisms^10-11^. In the same vein, we show that rats demonstrate spatial movement patterns that recall those of humans in similar urban environments. Rat behaviour may thus offer an in-vivo means for testing and analyzing the spatial cognitive principles of specific urban designs and for inferring how humans may perceive a particular urban environment and orient in it

Complete quantum state selectivity in cold molecular beams using deflection-resistant dark states in a STIRAP configuration

One of the main goals of chemical dynamics is the creation of molecular beams composed of a single (vibrational, rotational, and magnetic) quantum state of choice. In this paper we show that it is possible to achieve {\it complete} quantum state selectivity by producing resistance to electromagnetically induced deflection (EID) and that the state to be selected can be "dialed in" at will. We illustrate the method by showing in detail how to purify thermal beams of the LiRb and IF molecules to yield molecular beams composed of a variety of pre-chosen single internal quantum states and/or superpositions of such states. We expect that this method will be implemented in all subsequent explorations of the fundamentals of chemical reactions and their control, and the use of cold molecules as a vehicle for studying some of the most profound issues of quantum dynamics.Comment: 5 pages 4 figure

Pure Leptonic Radiative Decays B±,Ds→ℓνγB^\pm, D_s\to\ell\nu\gamma and the Annihilation Graph

Pure leptonic radiative decays of heavy-light mesons are calculated using a very simple non-relativistic model. Dominant contribution originates from photon emission from light initial quark. We find $BR(B^\pm\to\ell\nu\gamma)\sim3.5\times10^{-6}$ and $BR(D_s\to \ell\nu\gamma)\sim1.7 \times10^{-4}$. The importance of these reactions to clarify the dynamics of the annihilation graph is emphasized.Comment: 7 pages, LaTeX, 3 figure

Collider signals of a composite Higgs in the Standard Model with four generations

Recent fits of electroweak precision data to the Standard Model (SM) with a 4th sequential family (SM4) point to a possible "three-prong composite solution": (1) the Higgs mass is at the TeV-scale, (2) the masses of the 4th family quarks t',b' are of O(500) GeV and (3) the mixing angle between the 4th and 3rd generation quarks is of the order of the Cabibbo angle, \theta_{34} ~ O(0.1). Such a manifestation of the SM4 is of particular interest as it may suggest that the Higgs is a composite state, predominantly of the 4th generation heavy quarks. Motivated by the above, we show that the three-prong composite solution to the SM4 can have interesting new implications for Higgs phenomenology. For example, the Higgs can decay to a single heavy 4th generation quark via the 3-body decays (through an off-shell t' or b') H -> t'(bar) t'* -> t'(bar) b W+ and H -> b'(bar) b'* -> b'(bar) t W-. These flavor diagonal decays can be dramatically enhanced at the LHC (by several orders of magnitudes) due to the large width effects of the resonating heavy Higgs in the processes gg -> H -> t'(bar) t'* -> t'(bar) b W+ and gg -> H -> b'(bar) b'* -> b'(bar) t W-, thus yielding a viable signal above the corresponding continuum QCD production rates. In addition, the Higgs can decay to a single t' and b' in the loop-generated flavor changing (FC) channels H -> b' b(bar), t' t(bar). These FC decays are essentially "GIM-free" and can, therefore, have branching ratios as large as 10^{-4} - 10^{-3}.Comment: As published in Phys.Lett.B688:195-201,201