152 research outputs found

    Ultimate decoherence border for matter-wave interferometry

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    Stochastic backgrounds of gravitational waves are intrinsic fluctuations of spacetime which lead to an unavoidable decoherence mechanism. This mechanism manifests itself as a degradation of the contrast of quantum interferences. It defines an ultimate decoherence border for matter-wave interferometry using larger and larger molecules. We give a quantitative characterization of this border in terms of figures involving the gravitational environment as well as the sensitivity of the interferometer to gravitational waves. The known level of gravitational noise determines the maximal size of the molecular probe for which interferences may remain observable. We discuss the relevance of this result in the context of ongoing progresses towards more and more sensitive matter-wave interferometry.Comment: 4 page

    Second-order corrections to the non-commutative Klein-Gordon equation with a Coulomb potential

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    We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the second-order corrections in the non-commutativity parameter. Phenomenologically we show that non-commutativity is the source of lamb shift corrections.Comment: 12 pages, no figure

    Bounds on gravitational wave backgrounds from large distance clock comparisons

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    Our spacetime is filled with gravitational wave backgrounds that constitute a fluctuating environment created by astrophysical and cosmological sources. Bounds on these backgrounds are obtained from cosmological and astrophysical data but also by analysis of ranging and Doppler signals from distant spacecraft. We propose here a new way to set bounds on those backgrounds by performing clock comparisons between a ground clock and a remote spacecraft equipped with an ultra-stable clock, rather than only ranging to an onboard transponder. This technique can then be optimized as a function of the signal to be measured and the dominant noise sources, leading to significant improvements on present bounds in a promising frequency range where different theoretical models are competing. We illustrate our approach using the SAGAS project which aims to fly an ultra stable optical clock in the outer solar system.Comment: 10 pages, 8 figures, minor amendment

    Ingestions Alimentaires Et Performances De Production Et De Reproduction Des Lapines (Oryctolagus Cuniculus) Gestantes Nourries Avec Des Aliments Contenant Des Feuilles De Neem (Azadirachta Indica)

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    This study was conducted as part of a series of experiments on the use of dried leaves for the production of complete rabbit feed. For this purpose, 120 female rabbits, distributed in 4 batches (N0, N5, N10 and N15) with the same number (30) and homogeneous average weights (2595 g to 2708.7 g) were followed before and during pregnancy. Each of the 4 lot were composed, in the same proportion, of nulliparous and multiparous females. Those animals were subjected to four Azadirachta indica leaves based foods in different proportions: N0: 0%; N5: 5%; N10: 10% and N15: 15%. Our data shows that the gestation rates were as follows for the four lots: N0 (90%), N5 (80%) and N10 (90%) and N15 (76.67%). Except a single female from lot N10, all females were pregnant and gave birth. No significant difference (P> 0.05) was found between the mean of total daily consumptions among the pregnant rabbits of the four batches that ranged from 169.40 to 198.31 g / d. The average litters of the batches N0 (5.33 rabbits / mother), N5 (6.5 rabbits / mother) and N10 (5.61 rabbits / mother) were similar (P> 0.05) but higher (P 0.05). On the other hand, no difference (P> 0.05) was observed between the average weights of the rabbits of the control batch N0 (59.06 g) and those of N5 and N15

    Strong fisheries management and governance positively impact ecosystem status

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    Fisheries have had major negative impacts on marine ecosystems, and effective fisheries management and governance are needed to achieve sustainable fisheries, biodiversity conservation goals and thus good ecosystem status. To date, the IndiSeas programme (Indicators for the Seas) has focussed on assessing the ecological impacts of fishing at the ecosystem scale using ecological indicators. Here, we explore fisheries Management Effectiveness' and Governance Quality' and relate this to ecosystem health and status. We developed a dedicated expert survey, focused at the ecosystem level, with a series of questions addressing aspects of management and governance, from an ecosystem-based perspective, using objective and evidence-based criteria. The survey was completed by ecosystem experts (managers and scientists) and results analysed using ranking and multivariate methods. Results were further examined for selected ecosystems, using expert knowledge, to explore the overall findings in greater depth. Higher scores for Management Effectiveness' and Governance Quality' were significantly and positively related to ecosystems with better ecological status. Key factors that point to success in delivering fisheries and conservation objectives were as follows: the use of reference points for management, frequent review of stock assessments, whether Illegal, Unreported and Unregulated (IUU) catches were being accounted for and addressed, and the inclusion of stakeholders. Additionally, we found that the implementation of a long-term management plan, including economic and social dimensions of fisheries in exploited ecosystems, was a key factor in successful, sustainable fisheries management. Our results support the thesis that good ecosystem-based management and governance, sustainable fisheries and healthy ecosystems go together.IOC-UNESCO; EuroMarine; European FP7 MEECE research project; European Network of Excellence Eur-Oceans; FRB EMIBIOS project [212085]info:eu-repo/semantics/publishedVersio

    Experiences of outbreak laboratory management in the Ebola Disease outbreak in West-Africa 2014-2015

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    During the Ebola Disease outbreak in 2014-2015 West-Africa about 24 organizations operated laboratories at 40 sites in Guinea, Sierra Leone and Liberia. Representatives of ten organisations which had deployed laboratories to 16 sites across the three countries in West-Africa convened for a two day symposium in Dakar (4-5.02.16) to exchange their experiences. This article summarizes the discussion and points made during the discussion of the laboratory deployment experiences during the epidemic touching organisational and procedural issues.Additional co-authors: P Jansen van Vuren, K Stroecker, J Paweska, C Picard, H Sheeley, P Smit, AA Sal

    Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

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    Background After seven annual rounds of mass drug administration (MDA) in six Malian villages highly endemic for Wuchereria bancrofti (overall prevalence rate of 42.7%), treatment was discontinued in 2008. Surveillance was performed over the ensuing 5 years to detect recrudescence. Methods Circulating filarial antigen (CFA) was measured using immunochromatographic card tests (ICT) and Og4C3 ELISA in 6–7 year-olds. Antibody to the W. bancrofti infective larval stage (L3) antigen, Wb123, was tested in the same population in 2012. Microfilaraemia was assessed in ICT-positive subjects. Anopheles gambiae complex specimens were collected monthly using human landing catch (HLC) and pyrethrum spray catch (PSC). Anopheles gambiae complex infection with W. bancrofti was determined by dissection and reverse transcriptase polymerase chain reaction (RT-PCR) of mosquito pools. Results Annual CFA prevalence rates using ICT in children increased over time from 0% (0/289) in 2009 to 2.7% (8/301) in 2011, 3.9% (11/285) in 2012 and 4.5% (14/309) in 2013 (trend χ 2  = 11.85, df =3, P = 0.0006). Wb123 antibody positivity rates in 2013 were similar to the CFA prevalence by ELISA (5/285). Although two W. bancrofti-infected Anopheles were observed by dissection among 12,951 mosquitoes collected by HLC, none had L3 larvae when tested by L3-specific RT-PCR. No positive pools were detected among the mosquitoes collected by pyrethrum spray catch. Whereas ICT in 6–7 year-olds was the major surveillance tool, ICT positivity was also assessed in older children and adults (8–65 years old). CFA prevalence decreased in this group from 4.9% (39/800) to 3.5% (28/795) and 2.8% (50/1,812) in 2009, 2011 and 2012, respectively (trend χ 2  = 7.361, df =2, P = 0.0067). Some ICT-positive individuals were microfilaraemic in 2009 [2.6% (1/39)] and 2011 [8.3% (3/36)], but none were positive in 2012 or 2013. Conclusion Although ICT rates in children increased over the 5-year surveillance period, the decrease in ICT prevalence in the older group suggests a reduction in transmission intensity. This was consistent with the failure to detect infective mosquitoes or microfilaraemia. The threshold of ICT positivity in children may need to be re-assessed and other adjunct surveillance tools considered

    Experimental quantum-enhanced estimation of a lossy phase shift

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    When standard light sources are employed, the precision of the phase determination is limited by the shot noise. Quantum entanglement provides means to exceed this limit with the celebrated example of N00N states that saturate the ultimate Heisenberg limit on precision, but at the same time are extremely fragile to losses. In contrast, we provide experimental evidence that appropriately engineered quantum states outperform both standard and N00N states in the precision of phase estimation when losses are present.Comment: 5 page

    Quantitative analysis of particles, genomes and infectious particles in supernatants of haemorrhagic fever virus cell cultures

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    Information on the replication of viral haemorrhagic fever viruses is not readily available and has never been analysed in a comparative approach. Here, we compared the cell culture growth characteristics of haemorrhagic fever viruses (HFV), of the Arenaviridae, Filoviridae, Bunyaviridae, and Flavivridae virus families by performing quantitative analysis of cell culture supernatants by (i) electron microscopy for the quantification of virus particles, (ii) quantitative real time PCR for the quantification of genomes, and (iii) determination of focus forming units by coating fluorescent antibodies to infected cell monolayers for the quantification of virus infectivity
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