Jet coherence in QCD media: the antenna radiation spectrum

We study the radiation of a highly energetic partonic antenna in a colored state traversing a dense QCD medium. Resumming multiple scatterings of all involved constituents with the medium we derive the general gluon spectrum which encompasses both longitudinal color coherence between scattering centers in the medium, responsible for the well known Landau-Pomeranchuk-Migdal (LPM) effect, and transverse color coherence between partons inside a jet, leading, in vacuum, to angular ordering of the parton shower. We discuss shortly the onset of transverse decoherence which is reached in opaque media. In this regime, the spectrum consists of independent radiation off the antenna constituents.Comment: 15 pages, 2 figures, paper shortened and partly rewritten, references added, results unchange

Jet thermalization in QCD kinetic theory

We perform numerical studies in QCD kinetic theory to investigate the energy and angular profiles of a high energy parton - as a proxy for a jet produced heavy ion collisions - passing through a Quark-Gluon Plasma (QGP). We find that the fast parton loses energy to the plasma mainly via a radiative turbulent gluon cascade that transport energy locally from the jet down to the temperature scale where dissipation takes place. In this first stage, the angular structure of the turbulent cascade is found to be relatively collimated. However, when the lost energy reaches the plasma temperature is it rapidly transported to large angles w.r.t. the jet axis and thermalizes. We investigate the contribution of the soft jet constituents to the total jet energy. We show that for jet opening angles of about 0.3 rad or smaller the effect is negligible. Conversely, larger opening angles become more and more sensitive to the thermal component of the jet and thus to medium response. Our result showcase the importance of the jet cone size in mitigating or enhancing the details of dissipation in jet quenching observables.Comment: 41 pages, 11 figures

A community-engaged infection prevention and control approach to Ebola.

The real missing link in Ebola control efforts to date may lie in the failure to apply core principles of health promotion: the early, active and sustained engagement of affected communities, their trusted leaders, networks and lay knowledge, to help inform what local control teams do, and how they may better do it, in partnership with communities. The predominant focus on viral transmission has inadvertently stigmatized and created fear-driven responses among affected individuals, families and communities. While rigorous adherence to standard infection prevention and control (IPC) precautions and safety standards for Ebola is critical, we may be more successful if we validate and combine local community knowledge and experiences with that of IPC medical teams. In an environment of trust, community partners can help us learn of modest adjustments that would not compromise safety but could improve community understanding of, and responses to, disease control protocol, so that it better reflects their 'community protocol' (local customs, beliefs, knowledge and practices) and concerns. Drawing on the experience of local experts in several African nations and of community-engaged health promotion leaders in the USA, Canada and WHO, we present an eight step model, from entering communities with cultural humility, though reciprocal learning and trust, multi-method communication, development of the joint protocol, to assessing progress and outcomes and building for sustainability. Using examples of changes that are culturally relevant yet maintain safety, we illustrate how often minor adjustments can help prevent and treat the most serious emerging infectious disease since HIV/AIDS

Jet quenching and broadening: the transport coefficient q^\hat{q} in an anisotropic plasma

The jet quenching parameter $\hat{q}$ is analyzed for a quark jet propagating in an anisotropic plasma. The momentum anisotropy is calculated at high temperature of the underlying quark-gluon plasma. $\hat{q}$ is explicitly estimated in leading-logarithmic approximation by the broadening of the massless quark interacting via gluon exchange. A plasma instability is present. Strong indications are found that $\hat{q}$ is increasing with increasing anisotropy. Possible implications for the saturation scale $Q_s$ in $A-A$ collisions are pointed out.Comment: 1

Challenges faced by South African health services in implementing the Mental Health Care Act

The World Health Organization (WHO) has drawn attention to the growing global burden of mental disorders, and to recent advances in our understanding of and ability to treat these disorders. Mental disorders accounted for 12% of the global burden of disease in 2000. This figure will rise to 15% in 2020, when it is estimated that unipolar depression will be the second most disabling health condition in the world. In South Africa, neuropsychiatric disorders account for the second highest proportion of the local burden of disease, after HIV/AIDS

Unexplained HIV-1 infection in children — documenting cases and assessing for possible risk factors

Background. In the year 2000 we reported possible horizontal transmission of HIV-1 infection between two siblings. An investigation of three families, each with an HIV-infected child but seronegative parents, permitted this finding. Sexual abuse and surrogate breast-feeding were thought unlikely. The children had overlapping hospitalisation in a regional hospital. Since then several cases of unexplained HIV infection in children have been reported. A registry was established at Tygerberg Children’s Hospital for collection of data on the extent of horizontal or unexplained transmission of HIV in children. Study design. Retrospective chart review. Results. Fourteen children were identified, 12 from the Western Cape and 1 each from the Eastern Cape and KwaZulu-Natal. Thirteen (92%) had been hospitalised previously. In the Western Cape, children had been hospitalised in 8 hospitals. Ten of 13 (77%) were admitted as neonates and 9 of 13 (69%) had 2 or more admissions. Intravascular cannulation and intravenous drug administration occurred in all but 2 children before HIV diagnosis. Conclusion. We have confirmed HIV infection in a number of cases where the source of infection has been inadequately explained. Circumstantial evidence supports but does not prove nosocomial transmission. Further studies and identification of medical procedures conducive to the spread of HIV are urgently needed

Monte Carlo Tools for Jet Quenching

A thorough understanding of jet quenching on the basis of multi-particle final states and jet observables requires new theoretical tools. This talk summarises the status and propects of the theoretical description of jet quenching in terms of Monte Carlo generators.Comment: proceedings of the 22nd International Conference on Ultra-Relativistic Nucleus Nucleus Collisions (Quark Matter 2011