591 research outputs found

    Cooling atoms, particles and polarisable objects using dissipative dipole forces

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    Optical cooling methods are generally applicable to a very restricted range of species. As a means of overcoming this problem, we explore the effect of the retarded interaction of any polarisable particle (an atom, a molecule or even a micromirror) with itself, similarly to cavity-mediated cooling. We use the transfer matrix method, extended to allow us to handle moving scatterers, to explore the most general configuration of a mobile particle interacting with any 1D combination of fixed optical elements. Remarkably, this model allows a solution in closed form for the force acting on the particle, without any a priori restriction on the nature of the particle.peer-reviewe

    Reviewing progress: 7 Year Trends in Characteristics of Adults and Children Enrolled at HIV Care and Treatment Clinics in the United Republic of Tanzania.

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    To evaluate the on-going scale-up of HIV programs, we assessed trends in patient characteristics at enrolment and ART initiation over 7 years of implementation. Data were from Optimal Models, a prospective open cohort study of HIV-infected (HIV+) adults (>=15 years) and children (<15 years) enrolled from January 2005 to December 2011 at 44 HIV clinics in 3 regions of mainland Tanzania (Kagera, Kigoma, Pwani) and Zanzibar. Comparative statistics for trends in characteristics of patients enrolled in 2005--2007, 2008--2009 and 2010--2011 were examined. Overall 62,801 HIV+ patients were enrolled: 58,102(92.5%) adults, (66.5% female); 4,699(7.5%) children.Among adults, pregnant women enrolment increased: 6.8%, 2005--2007; 12.1%, 2008--2009; 17.2%, 2010--2011; as did entry into care from prevention of mother-to-child HIV transmission (PMTCT) programs: 6.6%, 2005--2007; 9.5%, 2008--2009; 12.6%, 2010--2011. WHO stage IV at enrolment declined: 27.1%, 2005--2007; 20.2%, 2008--2009; 11.1% 2010--2011. Of the 42.5% and 29.5% with CD4+ data at enrolment and ART initiation respectively, median CD4+ count increased: 210cells/muL, 2005--2007; 262cells/muL, 2008--2009; 266cells/muL 2010--2011; but median CD4+ at ART initiation did not change (148cells/muL overall). Stavudine initiation declined: 84.9%, 2005--2007; 43.1%, 2008--2009; 19.7%, 2010--2011.Among children, median age (years) at enrolment decreased from 6.1(IQR:2.7-10.0) in 2005--2007 to 4.8(IQR:1.9-8.6) in 2008--2009, and 4.1(IQR:1.5-8.1) in 2010--2011 and children <24 months increased from 18.5% to 26.1% and 31.5% respectively. Entry from PMTCT was 7.0%, 2005--2007; 10.7%, 2008--2009; 15.0%, 2010--2011. WHO stage IV at enrolment declined from 22.9%, 2005--2007, to 18.3%, 2008--2009 to 13.9%, 2010--2011. Proportion initiating stavudine was 39.8% 2005--2007; 39.5%, 2008--2009; 26.1%, 2010--2011. Median age at ART initiation also declined significantly. Over time, the proportion of pregnant women and of adults and children enrolled from PMTCT programs increased. There was a decline in adults and children with advanced HIV disease at enrolment and initiation of stavudine. Pediatric age at enrolment and ART initiation declined. Results suggest HIV program maturation from an emergency response

    LIBOR: Origins, Economics, Crisis, Scandal, and Reform

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    The London Interbank Offered Rate (LIBOR) is a widely used indicator of funding conditions in the interbank market. As of 2013, LIBOR underpins more than $300 trillion of financial contracts, including swaps and futures, in addition to trillions more in variable-rate mortgage and student loans. LIBOR's volatile behavior during the financial crisis provoked questions surrounding its credibility. Ongoing regulatory investigations have uncovered misconduct by a number of financial institutions. Policymakers across the globe now face the task of reforming LIBOR in the aftermath of the scandal and crisis

    Automatic computer algorithms for beam-based setup of the LHC collimators

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    Beam-based setup of the LHC collimators is necessary to establish the beam centers and beam sizes at the collimator locations and determine the operational settings during various stages of the LHC machine cycle. Automatic software algorithms have been successful in reducing the costly beam time required for the alignment, as well as significantly reducing human error. In this paper, the beam-based alignment procedure is described, and the design of algorithms such as a BLM feedback loop, parallel collimator alignment, pattern recognition of BLM loss spikes, automatic loss threshold selection and coarse BPM-interpolation guided alignment is explained. A comparison on the alignment results from the 2010 to the 2012 LHC runs is presented to illustrate the improvements achieved with the automatic algorithms.peer-reviewe

    Flexibility premium of emissions permits

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    Investments in abatement technology are often characterised by irreversibility and significant implementation lags, whereas emissions permits can be traded at any time. As such, abatement and emissions permit trading systems are hardly perfect substitutes. We formally study the flexibility of emissions permits and propose a unified framework to rationalise the impact of both investment/divestment lags and irreversibility in relation to the price of emissions permits. Using option pricing concepts, we reformulate the technology adoption problem in terms of the technology’s characteristics (irreversibility and implementation lags) and offer a conceptual quantification of the flexibility premium of emissions permits

    Safeguarding gains in the Sexual and Reproductive Health and AIDS Response amidst COVID-19: The Role of African Civil Society

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    We outline the role of African Civil Society in safeguarding gains registered to date in the sexual and reproductive health and HIV response. We make a case why civil society organizations (CSOs) must vigilantly be engaged in the COVID-19 response in Africa. Lockdown disruptions, and rerouting of health funds to the pandemic, have impeded access to essential Sexual and Reproductive Health (SRH), and social protection services. Compounded by pre-existing inequalities faced by vulnerable populations, poor SRH outcomes amid COVID-19 calls for CSOs' intensified demand on accountability of Governments. CSOs also rapidly close community-health facility gaps and provide safety-nets to mitigate the COVID-19 gendered impact
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