1,419 research outputs found

    Angular momentum exchange between coherent light and matter fields

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    Full, three dimensional, time-dependent simulations are presented demonstrating the quantized transfer of angular momentum to a Bose-Einstein condensate from a laser carrying orbital angular momentum in a Laguerre-Gaussian mode. The process is described in terms of coherent Bragg scattering of atoms from a chiral optical lattice. The transfer efficiency and the angular momentum content of the output coupled vortex state are analyzed and compared with a recent experiment.Comment: 4 pages, 4 figure

    Evaluation and learning in public housing urban renewal

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    This report analyses how evaluation and learning from public housing renewal is informing policy development and delivery to maximise financial returns and socio-economic outcomes. The research was conducted pre-COVID-19. • Public housing renewal provides an opportunity for policy makers to give direction to urban reconfiguration processes. Since the 2000s public housing renewal has increasingly become part of a policy discourse that places emphasis on 'unlocking' under-utilised sites (i.e. public housing estates) for jobs, investment and urban renewal. In this intersection with urban renewal processes, mixed-tenure public housing renewal, in practice, becomes public housing urban renewal. • This research highlights a consistency of views across stakeholders (often on pragmatic grounds) regarding 'how public housing renewal works'. It is thus possible to conceptualise learning and evaluation in public housing renewal policy-making within an advocacy coalition framework (ACF). • An ACF framework focuses on the alignment of the beliefs, actions and interest of a range of stakeholders with respect to how policies work, or can work. Our use of the ACF is grounded in a consistency of views about 'how public housing renewal works', given the prevailing institutional and financial constraints, and the implication of this for the role of evaluation and learning, rather than any suggestion of a formal or informal actual coalition, or collusion, in agenda setting or public policy objectives. • Interviewees perceived evaluation to be one of several integral parts to the policy formation process. However, evaluations have frequently been summative, rather than formative in nature. In addition, stakeholders also relied on personal and institutional experience to inform policy development and decision-making. These learning dynamics have, over time, reinforced key aspects of the policy core belief within the advocacy coalition. • The policy core belief guiding public housing urban renewal is characterised by a shared belief in the instrumental role of land values and land value change as a means of reconciling multiple asset- and people-based outcomes, while controlling the cost of public policy to public budgets. Mixed tenure, housing density and the strategic leveraging of land are policies that also extract land value for public housing reinvestment and other public policy goals. • The central role of land and land value has raised concerns amongst tenants, groups external to the advocacy coalition, but also some of the interviewees that public housing renewal is increasingly driven by asset-based viability considerations and reduced government exposure to risk. While risk related to physical reconfiguration (public housing stock renewal) in this respect is reduced, other objectives (such as wider social and economic benefits for tenants) increasingly become shaped by - rather than shaping urban reconfiguration processes. • Core members of the public housing renewal advocacy coalition are state governments and private developers. Additional members are (in some cases) community housing providers (CHPs) and local governments. Policy formation within advocacy coalitions is shaped by multiple factors. This includes evaluations, but also reacting to external events and internal stakeholder dynamics. • In the contextual analysis in this research, change in relative income is used as an indicator of social and economic reconfiguration. Apart from Adelaide, census collection districts (CCD) subject to public housing renewal experienced little improvement in relative income status (1996-2016). • Citywide drivers (such as economic restructuring, urban sprawl containment, population growth) and neighbourhood drivers (such as economic obsolescence, relative incomes) are specific drivers of social and economic reconfiguration. These are evident in all three capital cities, leading to the potential to 'unlock' value through mixed tenure and public housing renewal. • Policy options exist that can unlock more inclusive conceptualisations of value, and shift the reliance on land value in the program logic of public housing renewal. The design of public housing renewal tenders, and strategies for implementation, offer considerable opportunity for policy experimentation; identification and evaluation of assumed causal relationships and benefits. A social infrastructure perspective provides a framework for 'unlocking' additional and renewal project-specific values. A number of tools already exist to estimate the (equivalent) monetary value of wider social and economic benefits

    Long-term methimazole therapy in Graves' hyperthyroidism and adverse reactions: a Danish multicenter study

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    PURPOSE: In this prospective multicenter study with patients newly diagnosed with Graves’ hyperthyroidism (GH), we studied the timing and characteristics of adverse drug reactions in patients treated with anti-thyroid drugs (ATD) for up to 48 months. METHODS: Patients with GH were treated with ATD until remission and hereafter with a low-dose regime to keep the patients in remission. The patients were followed with blood samples and recording of adverse events approximately every second month for the first 2 years and every third month for the following 2 years. RESULTS: We included 208 patients and the patients were treated for a median of 22 (range: 0.5–49) months. Ten percent of the patients experienced adverse drug reactions and 75% of the cases occurred during the first 6 months. After 24 months, the methimazole dose was lowered to 5 mg/day, and after this time point, no further adverse drug reactions were recorded. Skin reactions were the most prominent reaction, comprising 68% of the registered reactions, and no hepatic and bonemarrow affection was recorded. CONCLUSION: With this study, we report the frequency, timing of occurrence, and characteristics of adverse drug reactions when treating GH with the ATD drug methimazole for up to 48 months. Long-term low-dose methimazole treatment can be a cost-effective and straightforward treatment option if adverse drug reactions such as severe hepatic and bone marrow affection are kept in mind

    Theory of the optical absorption of light carrying orbital angular momentum by semiconductors

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    We develop a free-carrier theory of the optical absorption of light carrying orbital angular momentum (twisted light) by bulk semiconductors. We obtain the optical transition matrix elements for Bessel-mode twisted light and use them to calculate the wave function of photo-excited electrons to first-order in the vector potential of the laser. The associated net electric currents of first and second-order on the field are obtained. It is shown that the magnetic field produced at the center of the beam for the ℓ=1\ell=1 mode is of the order of a millitesla, and could therefore be detected experimentally using, for example, the technique of time-resolved Faraday rotation.Comment: Submitted to Phys. Rev. Lett. (23 Jan 2008

    Static Properties of Trapped Bose-Fermi Mixed Condensate of Alkali Atoms

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    Static properties of a bose-fermi mixture of trapped potassium atoms are studied in terms of coupled Gross-Pitaevskii and Thomas-Fermi equations for both repulsive and attractive bose-fermi interatomic potentials. Qualitative estimates are given for solutions of the coupled equations, and the parameter regions are obtained analytically for the boson-density profile change and for the boson/fermion phase separation. Especially, the parameter ratio RintR_{int} is found that discriminates the region of the large boson-profile change. These estimates are applied for numerical results for the potassium atoms and checked their consistency. It is suggested that a small fraction of fermions could be trapped without an external potential for the system with an attractive boson-fermion interaction.Comment: 8 pages,5 figure

    Rapidity and centrality dependence of particle production for identified hadrons in Cu+Cu collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

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    The BRAHMS collaboration has measured transverse momentum spectra of pions, kaons, protons and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at sNN=200\sqrt{s_{NN}} = 200 GeV. As the collisions become more central the collective radial flow increases while the temperature of kinetic freeze-out decreases. The temperature is lower and the radial flow weaker at forward rapidity. Pion and kaon yields with transverse momenta between 1.5 and 2.5 GeV/c are suppressed for central collisions relative to scaled p+pp+p collisions. This suppression, which increases as the collisions become more central is consistent with jet quenching models and is also present with comparable magnitude at forward rapidity. At such rapidities initial state effects may also be present and persistence of the meson suppression to high rapidity may reflect a combination of jet quenching and nuclear shadowing. The ratio of protons to mesons increases as the collisions become more central and is largest at forward rapidities.Comment: 19 pages, 11 figures and 6 table

    Cover crop composition mediates the constraints and benefits of roller crimping and incorporation in organic white cabbage production

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    Roller-crimping of cover crops grown during winter may facilitate reduced tillage efforts in organic vegetable production. A one-year field experiment was conducted twice (autumn 2015-2017) in sandy loam soil in Denmark testing two cover crop termination systems, roller-crimping (RC) without tillage before crop planting, and full incorporation by tillage (FI) of mowed cover crops in organic white cabbage (Brassica oleracea L. convar. capitata var. capitata f. alba) production. Three legume species were investigated: winter faba bean (Vicia faba L.), winter pea (Pisum sativum L.), hairy vetch (Vicia villosa Roth), in pure stands or in a mixture with winter rye (Secale cereale L.). Roller-crimping reduced total white cabbage biomass by 31% (2016) and 19% (2017). Marketable white cabbage yield was 100% (2016) or 24% (2017) lower under RC than FI, likely caused by delayed N release from cover crops and reduced soil dehydrogenase activity. White cabbage root growth was reduced by RC following pea/rye, where N availability was low. Despite reduced root growth and yield, RC still had the advantage of reducing weed growth by 63% compared with FI three weeks after cover crop termination in 2017 and of decreasing N leaching risk, indicated by reduced soil mineral N content in 0.5-1.5 m depth in autumn. Marketable yield was 35% higher following legumes compared with legume/rye mixtures in both termination systems in 2017, due to 105 kg N ha−1 higher mineral soil N content in 0-2.5 m depth in the spring and faster N mineralisation from plant material with a lower C/N ratio. This yield increase corresponded with increased root growth following RC legumes. In contrast, legume/rye mixtures had the advantage of decreasing weed growth by 50-68% and N leaching risk by 22 kg ha−1 in 0.5−2 m depth. Although RC demonstrated ecological benefits such as weed suppression and indicated reduced N leaching risk, the trade-off with yield losses could create a barrier to adoption. This trade-off could be mitigated by using pure legume cover crops and by improving management of supplemental N fertility

    Rapidity dependence of deuteron production in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

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    We have measured the distributions of protons and deuterons produced in high energy heavy ion Au+Au collisions at RHIC over a very wide range of transverse and longitudinal momentum. Near mid-rapidity we have also measured the distribution of anti-protons and anti-deuterons. We present our results in the context of coalescence models. In particular we extract the "volume of homogeneity" and the average phase-space density for protons and anti-protons. Near central rapidity the coalescence parameter B2(pT)B_2(p_T) and the space averaged phase-space density (pT) (p_T) are very similar for both protons and anti-protons. For protons we see little variation of either B2(pT)B_2(p_T) or the space averaged phase-space density as the rapidity increases from 0 to 3. However both these quantities depend strongly on pTp_T at all rapidities. These results are in contrast to lower energy data where the proton and anti-proton phase-space densities are different at yy=0 and both B2B_2 and ff depend strongly on rapidity.Comment: Document updated after proofs received from PR
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