Hˉ+\bar{\textrm{H}}^{+} Sympathetic Cooling Simulations with a Variable Time Step

In this paper we present a new variable time step criterion for the velocity-Verlet algorithm allowing to correctly simulate the dynamics of charged particles exchanging energy via Coulomb collisions while minimising simulation time. We present physical arguments supporting the use of the criterion along with numerical results proving its validity. We numerically show that $\bar{\textrm{H}}^{+}$ ions with 18 meV initial energy can be captured and sympathetically cooled by a Coulomb crystal of $\textrm{Be}^{+}$ and $\textrm{HD}^{+}$ in less than 10 ms, an important result for the GBAR project.Comment: LEAP 2016 proceedin

Passive infrared bullet detection and tracking

An apparatus and method for passively detecting a projectile such as, for example, a bullet using a passive infrared detector. A passive infrared detector is focused onto a region in which a projectile is expected to be located. Successive images of infrared radiation in the region are recorded. Background infrared radiation present in the region is suppressed such that second successive images of infrared radiation generated by the projectile as the projectile passes through the region are produced. A projectile path calculator determines the path and other aspects of the projectile by using the second successive images of infrared radiation generated by the projectile. The present invention, in certain embodiments, also determines the origin of the path of the projectile and takes a photograph of the area surrounding the origin and/or fires at least one projectile at the area surrounding the origin of the path of the projectile

A Field Theory of Extended Particles Based on Covariant Harmonic Oscillator Wavefunctions

We attempt to combine the covariant harmonic oscillator (CHO) quark model with second quantized field theory. We review the CHO formalism for a system of two quarks (meson). We introduce a mesonic field Φ(x1 ,x2) that depends on the position of both quarks, and then derive the field equations from a covariant lagrangian L(x1, x2). The CHO equation allows a complete separation of the average meson coordinate X from the relative quark coordinate ξ. The CHO wavefunction in the field expresses the extended size and internal structure of the meson. Φ, describes mesons in the ground state and any excited state , with angular momentum ∞ mass^2. From Φ we construct conserved tensors like P^μ the meson momentum. We second quantize Φ in the X variable only and discuss the extended particle commutation relations. We investigate a Φ^3-type meson interaction where the vertex function is an overlap integral of the wavefunctions entering the interaction region. We derive a nonlinear integrodifferential equation for the U matrix , linearize and solve it by perturbation theory. The result is simple diagramatic rules for the S matrix. The S matrix is covariant and unitary. We do not find any contradiction between the principles of QFT and the CHO quark model. The Φ field theory includes scalar meson(point particle)theory as a special case, while its greater generality illuminates the difference between point and extended particles

An Activity Coordination System

Engineering and Applied Science

A Case–Crossover Study of Wintertime Ambient Air Pollution and Infant Bronchiolitis

We examined the association of infant bronchiolitis with acute exposure to ambient air pollutants. DESIGN: We employed a time-stratified case–crossover method and based the exposure windows on a priori, biologically based hypotheses. PARTICIPANTS: We evaluated effects in 19,901 infants in the South Coast Air Basin of California in 1995–2000 with a hospital discharge record for bronchiolitis in the first year of life (International Classification of Diseases, 9th Revision, CM466.1). EVALUATIONS/MEASUREMENTS: Study subjects’ ZIP code was linked to ambient air pollution monitors to derive exposures. We estimated the risk of bronchiolitis hospitalization associated with increases in wintertime ambient air pollutants using conditional logistic regression. RESULTS: We observed no increased risk after acute exposure to particulate matter ≤ 2.5 μm in aerodynamic diameter (PM(2.5)), carbon monoxide, or nitrogen dioxide. PM(2.5) exposure models suggested a 26–41% increased risk in the most premature infants born at gestational ages between 25 and 29 weeks; however, these findings were based on very small numbers. CONCLUSIONS: We found little support for a link between acute increases in ambient air pollution and infant bronchiolitis except modestly increased risk for PM(2.5) exposure among infants born very prematurely. In these infants, the periods of viral acquisition and incubation concurred with the time of increased risk. RELEVANCE TO PROFESSIONAL PRACTICE: We present novel data for the infant period and the key respiratory disease of infancy, bronchiolitis. Incompletely explained trends in rising bronchiolitis hospitalization rates and increasing number of infants born prematurely underscore the importance of evaluating the impact of ambient air pollution in this age group in other populations and studies