Activities of \gamma-ray emitting isotopes in rainwater from Greater Sudbury, Canada following the Fukushima incident

We report the activity measured in rainwater samples collected in the Greater Sudbury area of eastern Canada on 3, 16, 20, and 26 April 2011. The samples were gamma-ray counted in a germanium detector and the isotopes 131I and 137Cs, produced by the fission of 235U, and 134Cs, produced by neutron capture on 133Cs, were observed at elevated levels compared to a reference sample of ice-water. These elevated activities are ascribed to the accident at the Fukushima Dai-ichi nuclear reactor complex in Japan that followed the 11 March earthquake and tsunami. The activity levels observed at no time presented health concerns.Comment: 4 pages, 8 figure

Zero area singularities in general relativity and inverse mean curvature flow

First we restate the definition of a Zero Area Singularity, recently introduced by H. Bray. We then consider several definitions of mass for these singularities. We use the Inverse Mean Curvature Flow to prove some new results about the mass of a singularity, the ADM mass of the manifold, and the capacity of the singularity.Comment: 13 page

Signatures of electron correlations in the transport properties of quantum dots

The transition matrix elements between the correlated $N$ and $N\!+\!1$ electron states of a quantum dot are calculated by numerical diagonalization. They are the central ingredient for the linear and non--linear transport properties which we compute using a rate equation. The experimentally observed variations in the heights of the linear conductance peaks can be explained. The knowledge of the matrix elements as well as the stationary populations of the states allows to assign the features observed in the non--linear transport spectroscopy to certain transition and contains valuable information about the correlated electron states.Comment: 4 pages (revtex,27kB) + 3 figures in one file ziped and uuencoded (postscript,33kB), to appear in Phys.Rev.B as Rapid Communicatio

Single-pixel imaging with Fourier filtering: Application to vision through scattering media

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordWe present a novel approach for imaging through scattering media that combines the principles of Fourier spatial filtering and single-pixel imaging. We compare the performance of our single-pixel imaging setup with that of a conventional system. First, we show that a single-pixel camera does not reduce the frequency content of the object, when a small pinhole is used as a low-pass filter at the detection side. Second, we show that the introduction of Fourier gating improves the contrast of imaging through scattering media in both optical systems. We conclude that single-pixel imaging fits better than conventional imaging on imaging through scattering media by the Fourier gating

Effect of oxygen plasma etching on graphene studied with Raman spectroscopy and electronic transport

We report a study of graphene and graphene field effect devices after exposure to a series of short pulses of oxygen plasma. We present data from Raman spectroscopy, back-gated field-effect and magneto-transport measurements. The intensity ratio between Raman "D" and "G" peaks, I(D)/I(G) (commonly used to characterize disorder in graphene) is observed to increase approximately linearly with the number (N(e)) of plasma etching pulses initially, but then decreases at higher Ne. We also discuss implications of our data for extracting graphene crystalline domain sizes from I(D)/I(G). At the highest Ne measured, the "2D" peak is found to be nearly suppressed while the "D" peak is still prominent. Electronic transport measurements in plasma-etched graphene show an up-shifting of the Dirac point, indicating hole doping. We also characterize mobility, quantum Hall states, weak localization and various scattering lengths in a moderately etched sample. Our findings are valuable for understanding the effects of plasma etching on graphene and the physics of disordered graphene through artificially generated defects.Comment: 10 pages, 5 figure

Rotational dynamics induced by low energy binary collisions of quantum droplets

A theoretical analysis of the rotational dynamics induced by off axis binary collisions of quantum droplets constituted by ultracold atoms is reported. We focus on quantum droplets formed by degenerate dilute Bose gases made up from binary mixtures of alkaline atoms under feasible experimental conditions. The stability of the ground state is known to be longer for the chosen heteronuclear gases than for the homonuclear ones. In both cases, we find out that the dynamics seems to privilege a high similarity of the density of each atomic species. However, the evolution of the phase of the corresponding order parameter differs significantly for heteronuclear admixtures. We evaluate the fidelity as a figure of merit for the overlap between the order parameters of each atomic species. Dynamical evidence of the differences between the phase of the order parameters are predicted to manifest in their corresponding linear and angular momenta. We numerically verify that the total angular and linear momenta are conserved both during the collision. Some direct correlations between the Weber number and the impact parameter with the distribution of the dynamical variables are established.Comment: 12 pages, 6 figure

Higgs Sector with Spontaneous CP Violation in S(3) Standard Model

Conditions for spontaneous Charge-Parity (CP) violation in the scalar potential sector of general S(3) Higgs-doublet model (3HDM) are analyzed. An analysis of the Higgs sector of the minimal S(3)-invariant extension of the Standard Model including CP violation arising from the spontaneous breaking of the electroweak symmetry is presented. This extended Higgs sector with three SU(2) doublets Higgs fields with complex vev’s provides an interesting scenario to analyze the Higgs masses spectrum, trilinear self-couplings and CP violation. We present how the spontaneous electroweak symmetry breaking, coming from three S(3) Higgs fields, gives an interesting scenario with nine physical Higgs and three Goldstone bosons, when spontaneous CP violation arises from the Higgs field S(3) singlet Hs