Scattering of Bunched Fractionally Charged Quasiparticles

The charge of fractionally charged quasiparticles, proposed by Laughlin to explain the fractional quantum Hall effect (FQHE), was recently verified by measurements. Charge q=e/3 and e/5 (e is the electron charge), at filling factors nu=1/3 and 2/5, respectively, were measured. Here we report the unexpected bunching of fractional charges, induced by an extremely weak backscattering potential at exceptionally low electron temperatures (T<10 mK) - deduced from shot noise measurements. Backscattered charges q=nu e, specifically, q=e/3, q=2e/5, and q<3e/7, in the respective filling factors, were measured. For the same settings but at an only slightly higher electron temperature, the measured backscattered charges were q=e/3, q=e/5, and q=e/7. In other words, bunching of backscattered quasiparticles is taking place at sufficiently low temperatures. Moreover, the backscattered current exhibited distinct temperature dependence that was correlated to the backscattered charge and the filling factor. This observation suggests the existence of 'low' and 'high' temperature backscattering states, each with its characteristic charge and characteristic energy.Comment: 4 pages, 3 figure

Analysis of plasma instabilities and verification of the BOUT code for the Large Plasma Device

The properties of linear instabilities in the Large Plasma Device [W. Gekelman et al., Rev. Sci. Inst., 62, 2875 (1991)] are studied both through analytic calculations and solving numerically a system of linearized collisional plasma fluid equations using the 3D fluid code BOUT [M. Umansky et al., Contrib. Plasma Phys. 180, 887 (2009)], which has been successfully modified to treat cylindrical geometry. Instability drive from plasma pressure gradients and flows is considered, focusing on resistive drift waves, the Kelvin-Helmholtz and rotational interchange instabilities. A general linear dispersion relation for partially ionized collisional plasmas including these modes is derived and analyzed. For LAPD relevant profiles including strongly driven flows it is found that all three modes can have comparable growth rates and frequencies. Detailed comparison with solutions of the analytic dispersion relation demonstrates that BOUT accurately reproduces all characteristics of linear modes in this system.Comment: Published in Physics of Plasmas, 17, 102107 (2010

AB DIBLOCK COPOLYMER NANOPARTICLES VIA RAFT-MEDIATED POLYMERIZATION AS A PSEUDOSTATIONARY PHASE FOR ELECTROKINETIC CHROMATOGRAPHY

Electrokinetic chromatography (EKC) is a powerful analytical technique where analytes are separated according to their interactions with the pseudostationary and mobile phases within an electric field. Pseudostationary phases (PSPs) are an integral part of EKC and currently there are a limited number of PSPs available. As the fields of medicinal, environmental, and forensics chemistry grow, the necessity for PSPs with varied selectivity and high efficiencies becomes apparent. Until recently, polymeric synthesis of novel PSPs has been difficult due to the lack of control in structure and size distribution. Recent developments in polymeric synthesis, utilizing the Reversible addition−fragmentation chain-transfer polymerization (RAFT) process, have overcome the aforementioned problems. This study furthers the research of latex nanoparticles as PSPs. 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) was chosen as a novel ionic nanoparticle shell due to its high acidic character. Butyl acrylate was chosen for the hydrophobic core to stay consistent with previous work. Through the RAFT process, nanoparticles were successfully synthesized, demonstrating size control of both the hydrophilic block and hydrophobic block. The novel PSP performance was characterized in EKC by obtaining its electrophoretic mobility (ìep) with respect to size and pH. Retention and selectivity were characterized by linear solvation energy relationships (LSER) and compared with currently used PSPs

Maybe One Night

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Workload in Nursing: A Descriptive Study Using Cognitive Work Analysis

Nursing is a high workload profession, and excessive workload has been shown to have an adverse effect on patient care. This problem has been compounded by shortages of qualified nurses in hospitals, resulting in increased workload of the existing nursing staff. Prior research has focused on patient-staff ratios and skill mix to analyze the relationship of workload and degradation of care. The current research implemented a multi-dimensional model for analyzing nurses’ workload in a large general hospital. This method afforded the researcher the opportunity to examine a work domain from multiple angles. Nurses play versatile roles, and workload extends beyond the care of the patient with team and organizational responsibilities. The current research expanded on the concept of a multi-dimensional approach to workload in nursing. Workload drivers were introduced as multiple, unique factors that contributed to the totality of nursing workload. Prior research examined such factors as organizational and environmental factors (patient acuity) and factors that vary within a nurse’s shift (time pressure). The current study engaged in a systematic examination of these concepts, in addition to extracting workload drivers that were specific to the observation setting (different departments at Rochester General Hospital). A Cognitive Work Analysis (CWA) was conducted to map out the work domain of nurses, and identified sources of workload. This was a detailed and multi-stage investigation of nursing in terms of goals, functions, tasks, physical resources, and mental states and processes (decision making). The output was a collection of diagrams, tables, and interviews that illustrated areas in nursing that produced the most workload. A detailed integration of the material supported an estimation of workload experienced by nurses

The male world of football media and beer drinking: a case study of sports bars in Cape Town, South Africa

Includes bibliographical references.The present study explores the practice of football media viewing in sports bars. It is based on the constructivism research paradigm (Guba & Lincoln, 2005), a conceptualisation of media as a tool for social behaviour (Couldry, 2003) and James Wertsch’s (1998) Mediated Action Theory. The study analyses two dimensions of football media viewing in sports bars: it focuses on the psychological motivations and the socio-cultural structure. The study’s main objective is to understand both the role of media for the practice of football media viewing in sports bars and the constitution of gender during the practice. It is a subject worthy of in-depth examination as there is a lack of holistic, contextualised and critical research in media studies, particularly in the field of football media consumption. The study applied ethnographic observations of two sports bars in a middle-class suburb in Cape Town as well as on-site and off-site interviews. During this time the researcher balanced subjective experiences with social meanings and scientific theories in a reflexive and flexible manner. The results reveal a complex network of individual purposes and socio-cultural tools. On the individual level they explain which media aspects are important to serve patrons’ needs and why male patrons discriminate against women. On the socio-cultural level the results show how media, gender and other tools interact to influence patrons’ behaviour. The study concludes by suggesting how media can be used to create enjoyable social environments and how social structures can be altered to create a more equal society beyond the sports bar environment