Collisional Energy Loss of Fast Charged Particles in Relativistic Plasmas

Following an argument by Kirzhnits we rederive an exact expression for the energy loss of a fast charged particle in a relativistic plasma using the quantum field theoretical language. We compare this result to perturbative calculations of the collisional energy loss of an energetic electron or muon in an electron-positron plasma and of an energetic parton in the quark-gluon plasma.Comment: 9 pages, LATEX, 2 PostScript figure

In-between Images: Where is the Ground?

Joan Jonas’s large survey exhibition at Tate Modern (2018) highlighted the contemporary relevance of this pioneer of performance art in her juxtapositions of analogue and virtual methods. Her process often relies on a ground or stage where physical remnants of her performances are tangible. Drawing from these insights and exploring figure-ground relations through a selection of works by various artists and filmmakers, this article aims to challenge Hito Steyerl’s polemic that we might not need a ground within contemporary virtual image worlds. The consideration of case studies will be informed by philosophical reflections as to the relevance and scope of the idea of ground within the post-digital era

Using Active Learning Methods, Adult Learning Principles and the Identification of Critical to Quality (CTQ) Factors to Create Effective Site Staff Training Plans and Improve Quality Risk Management

Objective: The objective of this poster presentation is to help sponsors, monitors and clinical research site managers design and conduct more meaningful and effective site staff training activities in order to enhance the implementation of study protocols in accordance with the investigational plan and thus improve quality risk management. Content: The U.S. Food and Drug Administration (FDA), the International Council on Harmonization (ICH) and the European Medicines Agency (EMA) emphasize that sponsors should choose investigators, clinical research site staff and monitors that are qualified by education, training and experience. In addition, these entities have taken a more risk-based approach to managing and monitoring risks in recent years. This approach consists of focusing oversight on the risks related to human subjects protection, data integrity and investigation quality. All processes used to prevent and mitigate risks should be in direct proportion to the seriousness and likelihood of these risks. The ICH E6 (R2) noted that effective training in processes and procedures is one of the risk reduction activities that sponsors should employ. FDA’s 2013 guidance on risk-based monitoring noted that investigators and clinical research site staff need “meaningful training” prior to and during the conduct of a study in order to execute it correctly. In FY 2017, the most frequent finding on FDA Form 483 that was issued from inspections by FDA’s Bioresearch Monitoring Program was failure to conduct the investigation in accordance with the investigational plan. A common citation noted in warning letters to sponsors and investigators was the failure to have effective training and retraining activities. The challenge, therefore, is to design and conduct training activities that are meaningful and effective in order to correctly execute study protocols and reduce risks to human subjects protection, data integrity and investigation quality. Educational research has shown that active learning methods are much more effective at enhancing knowledge transfer and retention than passive learning methods such as reading, listening or watching a webcast. In this poster presentation, I will discuss various active learning methods that can be used to design and conduct meaningful and effective site training activities. I will discuss how these methods can be combined with adult learning principles and risk identification/assessment tools to design a site staff training plan that will identify the Critical to Quality (CTQ) factors, enhance the prevention and mitigation of risks that matter, and help staff to execute the study protocol in accordance with the investigational plan

Medication Adherence and its Implications for Clinical Research: An Example from Low Income, Urban Young Adults Living with HIV/AIDS

Consistent medication adherence by study participants is essential for producing valid and reliable safety and efficacy data in clinical trials. Adherence to investigational medications can be a challenge, particularly for study participants who have complex medication regimens, a stigmatized illness such as HIV/AIDS or a mental health disorder, and risk factors for poor adherence such as young or old age, poor health status, cognitive issues, low health literacy, and low socioeconomic status. A deep understanding of the study population’s beliefs, attitudes, motivations, and prior experiences regarding medication adherence can assist clinical research professionals with predicting medication adherence potential during the recruitment phase along with supporting medication adherence during the study conduct phase. I will present excerpts from in-depth interviews with 16 low income, urban young adults living with HIV/AIDS about their beliefs, attitudes, motivations, and prior experiences about medication adherence. I will discuss how this information can be used by clinical research professionals who conduct clinical trials with this population to predict and support medication adherence. I will also discuss how collecting deep, rich qualitative data about the study population can assist the clinical research team with predicting and supporting medication adherence of study participants. This presentation will be of interest to clinical research professionals who conduct clinical trials with low income, urban young adults living with HIV/AIDS as well as for those interested in predicting and supporting medication adherence among study participants in general

Damping Rate of a Yukawa Fermion at Finite Temperature

The damping of a massless fermion coupled to a massless scalar particle at finite temperature is considered using the Braaten-Pisarski resummation technique. First the hard thermal loop diagrams of this theory are extracted and effective Green's functions are constructed. Using these effective Green's functions the damping rate of a soft Yukawa fermion is calculated. This rate provides the most simple example for the damping of a soft particle. To leading order it is proportional to $g^2T$, whereas the one of a hard fermion is of higher order.Comment: 5 pages, REVTEX, postscript figures appended, UGI-94-0

Study of ambiguities in π−p→ΛK0\pi^-p\to \Lambda K^0 scattering amplitudes

Amplitudes for the reaction $\pi^-p\to \Lambda K^0$ are reconstructed from data on the differential cross section $d\sigma/d\Omega$, the recoil polarization $P$, and on the spin rotation parameter $\beta$. At low energies, no data on $\beta$ exist, resulting in ambiguities. An approximation using $S$ and $P$ waves leads only to a fair description of the data on $d\sigma/d\Omega$ and $P$; in this case, there are two sets of amplitudes. Including $D$ waves, the data on $d\sigma/d\Omega$ and $P$ are well reproduced by the fit but now, there are several distinct solutions which describe the data with identical precision. In the range where the spin rotation parameter $\beta$ was measured, a full and unambiguous reconstruction of the partial wave amplitudes is possible. The energy-independent amplitudes are compared to the energy dependent amplitudes which resulted from a coupled channel fit (BnGa2011-02) to a large data set including both pion and photo-induced reactions. Significant deviations are observed. Consistency between energy dependent and energy independent solutions by choosing the energy independent solution which is closest to the energy dependent solution. In a second step, the {\it known} energy dependent solution for low (or high) partial waves is imposed and only the high (or low) partial waves are fitted leading to smaller uncertainties

Photoproduction of η\eta mesons off neutrons from a deuteron target

A formalism is developed for the partial wave analysis of data on meson photoproduction off deuterons and applied to photoproduction of $\eta$ and $\pi^0$ mesons. Different interpretations of a dip-bump structure of the $\eta$ photoproduction cross section in the 1670 MeV region are presented and discussed. Helicity amplitudes for two low-mass $S_{11}$ states are determined.Comment: 11 pages, 13 figure