Bulk Viscosity of Interacting Hadrons

We show that first approximations to the bulk viscosity $\eta_v$ are expressible in terms of factors that depend on the sound speed $v_s$, the enthalpy, and the interaction (elastic and inelastic) cross section. The explicit dependence of $\eta_v$ on the factor $(\frac 13 - v_s^2)$ is demonstrated in the Chapman-Enskog approximation as well as the variational and relaxation time approaches. The interesting feature of bulk viscosity is that the dominant contributions at a given temperature arise from particles which are neither extremely nonrelativistic nor extremely relativistic. Numerical results for a model binary mixture are reported.Comment: 4 pages, 1 figure, Contribution to Quark Matter 2009, Knoxville, Tennessee, US

Attitudes and reported practice of paediatricians and child psychiatrists regarding the assessment and treatment of ADHD in Ireland

Objectives. This mixed-method national survey has obtained original data on attention deficit hyperactivity disorder (ADHD) attitudes, assessment and treatment regimes reported by paediatricians and child psychiatrists; and has compared their clinics. It has examined the extent of involvement of Irish paediatricians in the management of ADHD. Methods. A questionnaire was designed, based on a review of literature and ADHD guidelines, and piloted by expert clinicians. Universal recruitment was conducted among Child and Adolescent Mental Health Services (CAMHS) consultants (n = 71) and community/general paediatric consultants (n = 72). Quantitative and qualitative data was collected and analysed. Results. There was an overall response rate of 43%. A dedicated ADHD clinic is offered in 79% of CAMHS services, but only in one paediatric service. Participants reported that the assessment of ADHD involves multidisciplinary work and this was only established in CAMHS clinics. Medication is initiated by 82% of child psychiatrists and only 22% of paediatricians. Conclusions. This first national study of ADHD attitudes and practices presents comprehensive data regarding the management of children with ADHD in CAMHS and paediatric settings in Ireland. Paediatricians reported a minor role in managing ADHD. Study limitations are related to subjective reporting rather than case note audit, and a moderate response rate for the paediatricians’ participants

Draft genome sequence of the Streptococcus pneumoniae Avery strain A66

We have used HiSeq 2000 technology to generate a draft genome sequence of Streptococcus pneumoniae strain A66. This is a common study strain used in investigations of pneumococcal bacterium-host interactions and was used in the seminal genetic studies of Avery et al

Variability of the Accretion Stream in the Eclipsing Polar EP Dra

We present the first high time resolution light curves for six eclipses of the magnetic cataclysmic variable EP Dra, taken using the superconducting tunnel junction imager S-Cam2. The system shows a varying eclipse profile between consecutive eclipses over the two nights of observation. We attribute the variable stream eclipse after accretion region ingress to a variation in the amount and location of bright material in the accretion stream. This material creates an accretion curtain as it is threaded by many field lines along the accretion stream trajectory. We identify this as the cause of absorption evident in the light curves when the system is in a high accretion state. We do not see direct evidence in the light curves for an accretion spot on the white dwarf; however, the variation of the stream brightness with the brightness of the rapid decline in flux at eclipse ingress indicates the presence of some form of accretion region. This accretion region is most likely located at high colatitude on the white dwarf surface, forming an arc shape at the foot points of the many field lines channeling the accretion curtain.Comment: Accepted for publication in MNRAS (7 pages

Dissipative Field Theory with Caldeira-Leggett Method and its Application to Disoriented Chiral Condensation

The effective field theory including the dissipative effect is developed based on the Caldeira-Leggett theory at the classical level. After the integration of the small field fluctuations considered as the field radiation, the integro-differential field equation is given and shown to include the dissipative effects. In that derivation, special cares should be taken for the boundary condition of the integration. Application to the linear sigma model is given, and the decay process of the chiral condensate is calculated with it, both analytically in the linear approximation and numerically. With these results, we discuss the stability of chiral condensates within the quenched approximation.Comment: 16pages, ReV-Te

Quantum Operation Time Reversal

The dynamics of an open quantum system can be described by a quantum operation, a linear, complete positive map of operators. Here, I exhibit a compact expression for the time reversal of a quantum operation, which is closely analogous to the time reversal of a classical Markov transition matrix. Since open quantum dynamics are stochastic, and not, in general, deterministic, the time reversal is not, in general, an inversion of the dynamics. Rather, the system relaxes towards equilibrium in both the forward and reverse time directions. The probability of a quantum trajectory and the conjugate, time reversed trajectory are related by the heat exchanged with the environment.Comment: 4 page

The production of a non-homogeneous classical pion field and the distribution of the neutral and charged pions

The probability distribution $dw/df$ as a function of the ratio $f=n_0/n_{tot}$ of the neutral to total multiplicities is calculated for the classical pion fields quickly varying in space and time.Comment: 6 pages, 1 .eps figure, using epsfig, submitted to Phys.Let

Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat: an eddy covariance study

Coralline algal (maerl) beds are widespread, slow-growing, structurally complex perennial habitats that support high biodiversity, yet are significantly understudied compared to seagrass beds or kelp forests. We present the first eddy covariance (EC) study on a live maerl bed, assessing the community benthic gross primary productivity (GPP), respiration (R), and net ecosystem metabolism (NEM) derived from diel EC time series collected during 5 seasonal measurement campaigns in temperate Loch Sween, Scotland. Measurements were also carried out at an adjacent (~20 m distant) permeable sandy habitat. The O2 exchange rate was highly dynamic, driven by light availability and the ambient tidally-driven flow velocity. Linear relationships between the EC O2 fluxes and available light indicate that the benthic phototrophic communities were lightlimited. Compensation irradiance (Ec) varied seasonally and was typically ~1.8-fold lower at the maerl bed compared to the sand. Substantial GPP was evident at both sites; however, the maerl bed and the sand habitat were net heterotrophic during each sampling campaign. Additional inputs of ~4 and ~7 mol m-2 yr-1 of carbon at the maerl bed and sand site, respectively, were required to sustain the benthic O2 demand. Thus, the 2 benthic habitats efficiently entrap organic carbon and are sinks of organic material in the coastal zone. Parallel deployment of 0.1 m2 benthic chambers during nighttime revealed O2 uptake rates that varied by up to ~8-fold between replicate chambers (from -0.4 to -3.0 mmol O2 m-2 h-1; n = 4). However, despite extensive O2 flux variability on meter horizontal scales, mean rates of O2 uptake as resolved in parallel by chambers and EC were typically within 20% of one another

Fluctuation and flow probes of early-time correlations in relativistic heavy ion collisions

Fluctuation and correlation observables are often measured using multi-particle correlation methods and therefore mutually probe the origins of genuine correlations present in multi-particle distribution functions. We investigate the common influence of correlations arising from the spatially inhomogeneous initial state on multiplicity and momentum fluctuations as well as flow fluctuations. Although these observables reflect different aspects of the initial state, taken together, they can constrain a correlation scale set at the earliest moments of the collision. We calculate both the correlation scale in an initial stage Glasma flux tube picture and the modification to these correlations from later stage hydrodynamic flow and find quantitative agreement with experimental measurements over a range of collision systems and energies.Comment: Proceedings of the 28th Winter Workshop on Nuclear Dynamics, Dorado del Mar, Puerto Rico, April 7-14, 201

Globally controlled universal quantum computation with arbitrary subsystem dimension

We introduce a scheme to perform universal quantum computation in quantum cellular automata (QCA) fashion in arbitrary subsystem dimension (not necessarily finite). The scheme is developed over a one spatial dimension $N$-element array, requiring only mirror symmetric logical encoding and global pulses. A mechanism using ancillary degrees of freedom for subsystem specific measurement is also presented.Comment: 7 pages, 1 figur