220 research outputs found

    Velocity-selective sublevel resonance of atoms with an array of current-carrying wires

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    Resonance transitions between the Zeeman sublevels of optically-polarized Rb atoms traveling through a spatially periodic magnetic field are investigated in a radio-frequency (rf) range of sub-MHz. The atomic motion induces the resonance when the Zeeman splitting is equal to the frequency at which the moving atoms feel the magnetic field oscillating. Additional temporal oscillation of the spatially periodic field splits a motion-induced resonance peak into two by an amount of this oscillation frequency. At higher oscillation frequencies, it is more suitable to consider that the resonance is mainly driven by the temporal field oscillation, with its velocity-dependence or Doppler shift caused by the atomic motion through the periodic field. A theoretical description of motion-induced resonance is also given, with emphasis on the translational energy change associated with the internal transition.Comment: 7 pages, 3 figures, final versio

    First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength

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    We present the first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations all corroborate the existing models for SASE FELs.Comment: 6 pages including 6 figures; e-mail: [email protected]

    Genetically Engineered Alginate Lyase-PEG Conjugates Exhibit Enhanced Catalytic Function and Reduced Immunoreactivity

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    Alginate lyase enzymes represent prospective biotherapeutic agents for treating bacterial infections, particularly in the cystic fibrosis airway. To effectively deimmunize one therapeutic candidate while maintaining high level catalytic proficiency, a combined genetic engineering-PEGylation strategy was implemented. Rationally designed, site-specific PEGylation variants were constructed by orthogonal maleimide-thiol coupling chemistry. In contrast to random PEGylation of the enzyme by NHS-ester mediated chemistry, controlled mono-PEGylation of A1-III alginate lyase produced a conjugate that maintained wild type levels of activity towards a model substrate. Significantly, the PEGylated variant exhibited enhanced solution phase kinetics with bacterial alginate, the ultimate therapeutic target. The immunoreactivity of the PEGylated enzyme was compared to a wild type control using in vitro binding studies with both enzyme-specific antibodies, from immunized New Zealand white rabbits, and a single chain antibody library, derived from a human volunteer. In both cases, the PEGylated enzyme was found to be substantially less immunoreactive. Underscoring the enzyme's potential for practical utility, >90% of adherent, mucoid, Pseudomonas aeruginosa biofilms were removed from abiotic surfaces following a one hour treatment with the PEGylated variant, whereas the wild type enzyme removed only 75% of biofilms in parallel studies. In aggregate, these results demonstrate that site-specific mono-PEGylation of genetically engineered A1-III alginate lyase yielded an enzyme with enhanced performance relative to therapeutically relevant metrics.Cystic Fibrosis Foundation (Research Development Program)National Center for Research Resources (U.S.) (P20RR018787-06

    The contribution of female community health volunteers (FCHVs) to maternity care in Nepal: a qualitative study.

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    BACKGROUND: In resource-poor settings, the provision of basic maternity care within health centres is often a challenge. Despite the difficulties, Nepal reduced its maternal mortality ratio by 80% from 850 to an estimated 170 per 100,000 live births between 1991 and 2011 to achieve Millennium Development Goal Five. One group that has been credited for this is community health workers, known as Female Community Health Volunteers (FCHVs), who form an integral part of the government healthcare system. This qualitative study explores the role of FCHVs in maternal healthcare provision in two regions: the Hill and Terai. METHODS: Between May 2014 and September 2014, 20 FCHVs, 11 health workers and 26 service users were purposefully selected and interviewed using semi-structured topic guides. In addition, four focus group discussions were held with 19 FCHVs. Data were analysed using thematic analysis. RESULTS: All study participants acknowledged the contribution of FCHVs in maternity care. All FCHVs reported that they shared key health messages through regularly held mothers' group meetings and referred women for health checks. The main difference between the two study regions was the support available to FCHVs from the local health centres. With regular training and access to medical supplies, FCHVs in the hill villages reported activities such as assisting with childbirth, distributing medicines and administering pregnancy tests. They also reported use of innovative approaches to educate mothers. Such activities were not reported in Terai. In both regions, a lack of monetary incentives was reported as a major challenge for already overburdened volunteers followed by a lack of education for FCHVs. CONCLUSIONS: Our findings suggest that the role of FCHVs varies according to the context in which they work. FCHVs, supported by government health centres with emphasis on the use of local approaches, have the potential to deliver basic maternity care and promote health-seeking behaviour so that serious delays in receiving healthcare can be minimised. However, FCHVs need to be reimbursed and provided with educational training to ensure that they can work effectively. The study underlines the relevance of community health workers in resource-poor settings

    New Light Source (NLS) project: conceptual design report

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    Risk governance in organizations

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    Dieses Buch dokumentiert 10 Jahre Risk-Governance-Forschung an der Universität Siegen. In 50 Beiträgen reflektieren Forscher und Praktiker Risk Governance vor dem Hintergrund ihrer eigenen Forschungen und/oder Erfahrungen und geben jeweils einen Entwicklungsimpuls für die Zukunft der Risk Governance. Das Buch zeigt die große Bandbreite und Tiefe des Forschungsgebietes auf und diskutiert Grundannahmen, Implementierungsfragen, die Rolle der Risk Governance als Transformationsmotor, ihre Wirkung in den verschiedenen betrieblichen Funktionen, Entwicklungsperspektiven und den Beitrag der Risk Governance zu einer nachhaltigen Ausrichtung von Unternehmen.This book documents 10 years of risk governance research at the University of Siegen. In 50 contributions, researchers and practitioners reflect on risk governance against the background of their own research and/or experience and provide a development impetus for the future of risk governance. The book shows the wide range and depth of the research field and discusses basic assumptions, implementation issues, the role of risk governance as transformation engine, its impact in the various operational functions, development perspectives, and the contribution of risk governance to a sustainable orientation of companies

    Reflecting strategic and conforming gendered experiences of community health workers using photovoice in rural Wakiso district, Uganda

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    BACKGROUND: Community health workers (CHWs) are an important human resource in Uganda as they are the first contact of the population with the health system. Understanding gendered roles of CHWs is important in establishing how they influence their performance and relationships in communities. This paper explores the differential roles of male and female CHWs in rural Wakiso district, Uganda, using photovoice, an innovative community-based participatory research approach. METHODS: We trained ten CHWs (five males and five females) on key concepts about gender and photovoice. The CHWs took photographs for 5 months on their gender-related roles which were discussed in monthly meetings. The discussions from the meetings were recorded, transcribed, and translated to English, and emerging data were analysed using content analysis in Atlas ti version 6.0.15. RESULTS: Although responsibilities were the same for both male and female CHWs, they reported that in practice, CHWs were predominantly involved in different types of work depending on their gender. Social norms led to men being more comfortable seeking care from male CHWs and females turning to female CHWs. Due to their privileged ownership and access to motorcycles, male CHWs were noted to be able to assist patients faster with referrals to facilities during health emergencies, cover larger geographic distances during community mobilization activities, and take up supervisory responsibilities. Due to the gendered division of labour in communities, male CHWs were also observed to be more involved in manual work such as cleaning wells. The gendered division of labour also reinforced female caregiving roles related to child care, and also made female CHWs more available to address local problems. CONCLUSIONS: CHWs reflected both strategic and conformist gendered implications of their community work. The differing roles and perspectives about the nature of male and female CHWs while performing their roles should be considered while designing and implementing CHW programmes, without further retrenching gender inequalities or norms
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