Cold state-selected molecular collisions and reactions.

Over the past decade, and particularly the past five years, a quiet revolution has been building at the border between atomic physics and experimental quantum chemistry. The rapid development of techniques for producing cold and even ultracold molecules without a perturbing rare-gas cluster shell is now enabling the study of chemical reactions and scattering at the quantum scattering limit with only a few partial waves contributing to the incident channel. Moreover, the ability to perform these experiments with nonthermal distributions comprising one or a few specific states enables the observation and even full control of state-to-state collision rates in this computation-friendly regime: This is perhaps the most elementary study possible of scattering and reaction dynamics.

Search for new physics in high pT like-sign dilepton events at CDF II.

We present a search for new physics in events with two high pT leptons of the same electric charge, using data with an integrated luminosity of 6.1 fb(-1). The observed data are consistent with standard model predictions. We set 95% C.L. lower limits on the mass of doubly charged scalars decaying to like-sign dileptons, m(H±±) > 190-245 GeV/c(2), assuming 100% BR to ee, µµ or eµ.

Search for a heavy particle decaying into an electron and a muon with the ATLAS detector in sqrt[s] = 7 TeV pp collisions at the LHC.

This Letter presents the first search for a heavy particle decaying into an e ± µ(-/+) final state in sqrt[s] = 7 TeV pp collisions at the LHC. The data were recorded by the ATLAS detector during 2010 and correspond to a total integrated luminosity of 35 pb(-1). No excess above the standard model background expectation is observed. Exclusions at 95% confidence level are placed on two representative models. In an R-parity violating supersymmetric model, tau sneutrinos with a mass below 0.75 TeV are excluded, assuming all R-parity violating couplings are zero except λ(311)' = 0.11 and λ312 = 0.07. In a lepton flavor violating model, a Z'-like vector boson with masses of 0.70-1.00 TeV and corresponding cross sections times branching ratios of 0.175-0.183 pb is excluded. These results extend to higher mass R-parity violating sneutrinos and lepton flavor violating Z's than previous constraints from the Tevatron.

Bio-enabled synthesis of metamaterials.

Biological systems offer more than an inspiration for the spontaneous hierarchical organization of matter at length scales between 1 and 1000 nm. They also provide useful principles and molecular building blocks that have recently emerged with the proven ability to generate extended three-dimensional structures of hybrid biotic/abiotic components arranged with molecular precision. These principles and tools draw from the methods of molecular biology and modern biochemistry and are expected to provide unmatched flexibility in building supramolecular architectures, notably structures made of artificial atoms whose coupled responses to electromagnetic or elastic excitations have been predicted to yield astonishing properties unparalleled by any conventional materials. To illustrate the potential of merging bio-enabled organization with metamaterials synthesis, we provide here a succinct overview of the architectural constraints leading to metamaterial behavior together with examples of biological material assembly that are particularly promising to comply with these constraints.

Recent advances in medical physics.

Some of the major interests in medical physics over the last few years have concerned the technical advances in Computed Tomography and high field Magnetic Resonance Imaging. This review discusses the introduction of Dual Source CT and explains how it can not only offer faster data acquisition but also operate with lower radiation doses. This provides enormous benefits for all patients, but for cardiac and pediatric examinations in particular. The advances in MRI at 7 T esla are also impressive, with better signal to noise; cardiac and musculoskeletal applications are discussed; technical improvements are work-in-progress for other applications.

[Development on measuring method for the parameters of orthopaedic biomechanics].

This paper introduces the development on the research of measuring theory for orthopaedic biomechanics in detail. Then, the measuring method and corresponding measuring device are also mentioned. Advantages, disadvantages and development for the device are also introduced. Finally, the research prospect for it is introduced.

On the accuracy of generalized Fokker-Planck transport equations in tissue optics.

Forward-peaked and large-angle scattering approximations of the radiative transport equation give rise to generalized Fokker-Planck equations whose main feature is the replacement of the integral scattering operator with differential operators in the direction-space variables. Using the P(N) method, an appraisal of generalized Fokker-Planck equations due to González-Rodríguez and Kim [Appl. Opt.47, 2599-2609 (2008)], Leakeas and Larsen [Nucl. Sci. Eng.137, 236-250 (2001), and J. Opt. Soc. Am. A20, 92-98 (2003)], and Pomraning [Math. Models Meth. Appl. Sci.2, 21-36 (1992)] is carried out by computing the relative error between the backscattered and transmitted surface flux predicted by the generalized Fokker-Planck equations and the transport equation with Henyey-Greenstein phase function for anisotropies ranging from 0 to 1. Generalized Fokker-Planck equations whose scattering operators incorporate large-angle scattering and possess eigenvalues similar to the integral scattering operator with Henyey-Greenstein phase function are found to minimize the relative error in the limit of unit anisotropy.

Two-step four-photon absorption.

We report a theoretical investigation of effective four-photon absorption (4PA) process and propose a two-step 4PA model of three-photon- induced excited-state absorption (ESA). Based on three-level rate-equation theory, we find an analytical result for the effective 4PA coefficient that depends on the three-photon absorption (3PA) cross-section, excited-state photophysical properties, and laser pulse duration. We present the analytical theory of the z-dependent nonlinear transmission for straightforwardly yet unambiguously evaluating the 3PA and effective 4PA coefficients simultaneously.

Physics and applications of atmospheric nonlinear optics and filamentation.

We review the properties and applications of ultrashort laser pulses in the atmosphere, with a particular focus on filamentation. Filamentation is a non-linear propagation regime specific of ultrashort and ultraintense laser pulses in the atmosphere. Typical applications include remote sensing of atmospheric gases and aerosols, lightning control, laser-induced spectroscopy, coherent anti-stokes Raman scattering, and the generation of sub-THz radiation.

Optical snakes and ladders: dispersion and nonlinearity in microcoil resonators.

Microcoil resonators are a radical new geometry for high Q resonators with unique linear features. In this paper I briefly summarise their linear properties before extending the analysis to nonlinear interactions in microcoil resonators. As expected such nonlinear resonators are bistable and exhibit hysteresis. Finally I discuss possible applications and extensions to such resonators.

An efficient method for the creation of tunable optical line traps via control of gradient and scattering forces.

Interparticle interaction energies and other useful physical characteristics can be extracted from the statistical properties of the motion of particles confined by an optical line trap. In practice, however, the potential energy landscape, U(x), imposed by the line provides an extra, and in general unknown, influence on particle dynamics. We describe a new class of line traps in which both the optical gradient and scattering forces acting on a trapped particle are designed to be linear functions of the line coordinate and in which their magnitude can be counterbalanced to yield a flat U(x). These traps are formed using approximate solutions to general relations concerning non-conservative optical forces that have been the subject of recent investigations [Y. Roichman, B. Sun, Y. Roichman, J. Amato-Grill, and D. G. Grier, Phys. Rev. Lett. 100, 013602-4 (2008).]. We implement the lines using holographic optical trapping and measure the forces acting on silica microspheres, demonstrating the tunability of the confining potential energy landscape. Furthermore, we show that our approach efficiently directs available laser power to the trap, in contrast to other methods.