341 research outputs found

    Stand-alone vacuum cell for compact ultracold quantum technologies

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    Compact vacuum systems are key enabling components for cold atom technologies, facilitating extremely accurate sensing applications. There has been important progress toward a truly portable compact vacuum system; however, size, weight, and power consumption can be prohibitively large, optical access may be limited, and active pumping is often required. Here, we present a centiliter-scale ceramic vacuum chamber with He-impermeable viewports and an integrated diffractive optic, enabling robust laser cooling with light from a single polarization-maintaining fiber. A cold atom demonstrator based on the vacuum cell delivers 10 7 laser-cooled 87Rb atoms per second, using minimal electrical power. With continuous Rb gas emission, active pumping yields a 17 day time constant. A vacuum cell, with no Rb dispensing and only passive pumping, has currently kept a similar pressure for more than 500 days. The passive-pumping vacuum lifetime is several years, which is estimated from short-term He throughput with many foreseeable improvements. This technology enables wide-ranging mobilization of ultracold quantum metrology

    Quantum Aspects of Supersymmetric Maxwell Chern-Simons Solitons

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    We study the various quantum aspects of the N=2N=2 supersymmetric Maxwell Chern-Simons vortex systems. The fermion zero modes around the vortices will give rise the degenerate states of vortices. We analyze the angular momentum of these zero modes and apply the result to get the supermultiplet structures of the vortex. The leading quantum correction to the mass of the vortex coming from the mode fluctuations is also calculated using various methods depending on the value of the coefficient of the Chern-Simons term κ\kappa to be zero, infinite and finite, separately. The mass correction is shown to vanish for all cases. Fermion numbers of vortices are also discussed.Comment: 40 pages, ReVTeX, HYUPT-94/04 SNUTP 94-6

    Trial of early, goal-directed resuscitation for septic shock.

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    BACKGROUND: Early, goal-directed therapy (EGDT) is recommended in international guidelines for the resuscitation of patients presenting with early septic shock. However, adoption has been limited, and uncertainty about its effectiveness remains. METHODS: We conducted a pragmatic randomized trial with an integrated cost-effectiveness analysis in 56 hospitals in England. Patients were randomly assigned to receive either EGDT (a 6-hour resuscitation protocol) or usual care. The primary clinical outcome was all-cause mortality at 90 days. RESULTS: We enrolled 1260 patients, with 630 assigned to EGDT and 630 to usual care. By 90 days, 184 of 623 patients (29.5%) in the EGDT group and 181 of 620 patients (29.2%) in the usual-care group had died (relative risk in the EGDT group, 1.01; 95% confidence interval [CI], 0.85 to 1.20; P=0.90), for an absolute risk reduction in the EGDT group of -0.3 percentage points (95% CI, -5.4 to 4.7). Increased treatment intensity in the EGDT group was indicated by increased use of intravenous fluids, vasoactive drugs, and red-cell transfusions and reflected by significantly worse organ-failure scores, more days receiving advanced cardiovascular support, and longer stays in the intensive care unit. There were no significant differences in any other secondary outcomes, including health-related quality of life, or in rates of serious adverse events. On average, EGDT increased costs, and the probability that it was cost-effective was below 20%. CONCLUSIONS: In patients with septic shock who were identified early and received intravenous antibiotics and adequate fluid resuscitation, hemodynamic management according to a strict EGDT protocol did not lead to an improvement in outcome. (Funded by the United Kingdom National Institute for Health Research Health Technology Assessment Programme; ProMISe Current Controlled Trials number, ISRCTN36307479.)

    Protocolised Management In Sepsis (ProMISe): a multicentre randomised controlled trial of the clinical effectiveness and cost-effectiveness of early, goal-directed, protocolised resuscitation for emerging septic shock.

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    BACKGROUND: Early goal-directed therapy (EGDT) is recommended in international guidance for the resuscitation of patients presenting with early septic shock. However, adoption has been limited and uncertainty remains over its clinical effectiveness and cost-effectiveness. OBJECTIVES: The primary objective was to estimate the effect of EGDT compared with usual resuscitation on mortality at 90 days following randomisation and on incremental cost-effectiveness at 1 year. The secondary objectives were to compare EGDT with usual resuscitation for requirement for, and duration of, critical care unit organ support; length of stay in the emergency department (ED), critical care unit and acute hospital; health-related quality of life, resource use and costs at 90 days and at 1 year; all-cause mortality at 28 days, at acute hospital discharge and at 1 year; and estimated lifetime incremental cost-effectiveness. DESIGN: A pragmatic, open, multicentre, parallel-group randomised controlled trial with an integrated economic evaluation. SETTING: Fifty-six NHS hospitals in England. PARTICIPANTS: A total of 1260 patients who presented at EDs with septic shock. INTERVENTIONS: EGDT (n = 630) or usual resuscitation (n = 630). Patients were randomly allocated 1 : 1. MAIN OUTCOME MEASURES: All-cause mortality at 90 days after randomisation and incremental net benefit (at £20,000 per quality-adjusted life-year) at 1 year. RESULTS: Following withdrawals, data on 1243 (EGDT, n = 623; usual resuscitation, n = 620) patients were included in the analysis. By 90 days, 184 (29.5%) in the EGDT and 181 (29.2%) patients in the usual-resuscitation group had died [p = 0.90; absolute risk reduction -0.3%, 95% confidence interval (CI) -5.4 to 4.7; relative risk 1.01, 95% CI 0.85 to 1.20]. Treatment intensity was greater for the EGDT group, indicated by the increased use of intravenous fluids, vasoactive drugs and red blood cell transfusions. Increased treatment intensity was reflected by significantly higher Sequential Organ Failure Assessment scores and more advanced cardiovascular support days in critical care for the EGDT group. At 1 year, the incremental net benefit for EGDT versus usual resuscitation was negative at -£725 (95% CI -£3000 to £1550). The probability that EGDT was more cost-effective than usual resuscitation was below 30%. There were no significant differences in any other secondary outcomes, including health-related quality of life, or adverse events. LIMITATIONS: Recruitment was lower at weekends and out of hours. The intervention could not be blinded. CONCLUSIONS: There was no significant difference in all-cause mortality at 90 days for EGDT compared with usual resuscitation among adults identified with early septic shock presenting to EDs in England. On average, costs were higher in the EGDT group than in the usual-resuscitation group while quality-adjusted life-years were similar in both groups; the probability that it is cost-effective is < 30%. FUTURE WORK: The ProMISe (Protocolised Management In Sepsis) trial completes the planned trio of evaluations of EGDT across the USA, Australasia and England; all have indicated that EGDT is not superior to usual resuscitation. Recognising that each of the three individual, large trials has limited power for evaluating potentially important subgroups, the harmonised approach adopted provides the opportunity to conduct an individual patient data meta-analysis, enhancing both knowledge and generalisability. TRIAL REGISTRATION: Current Controlled Trials ISRCTN36307479. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 97. See the NIHR Journals Library website for further project information

    Clinical practice: Breastfeeding and the prevention of allergy

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    The increase in allergic disease prevalence has led to heightened interest in the factors determining allergy risk, fuelled by the hope that by influencing these factors one could reduce the prevalence of allergic conditions. The most important modifiable risk factors for allergy are maternal smoking behaviour and the type of feeding. A smoke-free environment for the child (to be), exclusive breastfeeding for 4–6 months and the postponement of supplementary feeding (solids) until 4 months of age are the main measures considered effective. There is no place for restricted diets during pregnancy or lactation. Although meta-analyses suggest that hypoallergenic formula after weaning from breastfeeding grants protection against the development of allergic disease, the evidence is limited and weak. Moreover, all current feeding measures aiming at allergy prevention fail to show effects on allergic manifestations later in life, such as asthma. In conclusion, the allergy preventive effect of dietary interventions in infancy is limited. Counselling of future parents on allergy prevention should pay attention to these limitations

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

    Polymerase II Promoter Strength Determines Efficacy of microRNA Adapted shRNAs

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    Since the discovery of RNAi and microRNAs more than 10 years ago, much research has focused on the development of systems that usurp microRNA pathways to downregulate gene expression in mammalian cells. One of these systems makes use of endogenous microRNA pri-cursors that are expressed from polymerase II promoters where the mature microRNA sequence is replaced by gene specific duplexes that guide RNAi (shRNA-miRs). Although shRNA-miRs are effective in directing target mRNA knockdown and hence reducing protein expression in many cell types, variability of RNAi efficacy in cell lines has been an issue. Here we show that the choice of the polymerase II promoter used to drive shRNA expression is of critical importance to allow effective mRNA target knockdown. We tested the abundance of shRNA-miRs expressed from five different polymerase II promoters in 6 human cell lines and measured their ability to drive target knockdown. We observed a clear positive correlation between promoter strength, siRNA expression levels, and protein target knockdown. Differences in RNAi from the shRNA-miRs expressed from the various promoters were particularly pronounced in immune cells. Our findings have direct implications for the design of shRNA-directed RNAi experiments and the preferred RNAi system to use for each cell type

    Two transiting hot Jupiters from the WASP survey : WASP-150b and WASP-176b

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    Funding: The research leading to these results has received funding from the European Research Council under the FP/2007-2013 ERC grant Agreement No. 336480 and from the ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. A.C.C. acknowledges support from the UK Science and Technology Facilities Council (STFC)consolidated grant No. ST/R000824/1.We report the discovery of two transiting exoplanets from the WASP survey, WASP-150b and WASP-176b. WASP-150b is an eccentric (e = 0.38) hot Jupiter on a 5.6 day orbit around a V = 12.03, F8 main-sequence host. The host star has a mass and radius of 1.4 M⊙ and 1.7 R⊙ respectively. WASP-150b has a mass and radius of 8.5 MJ and 1.1 RJ, leading to a large planetary bulk density of 6.4 ρJ. WASP-150b is found to be ~3 Gyr old, well below its circularization timescale, supporting the eccentric nature of the planet. WASP-176b is a hot Jupiter planet on a 3.9 day orbit around a V = 12.01, F9 sub-giant host. The host star has a mass and radius of 1.3 M⊙ and 1.9 R⊙. WASP-176b has a mass and radius of 0.86 MJ and 1.5 RJ, respectively, leading to a planetary bulk density of 0.23 ρJ.Publisher PDFPeer reviewe

    The Osteology of the Basal Archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia

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    Proterosuchidae are the most taxonomically diverse archosauromorph reptiles sampled in the immediate aftermath of the Permo-Triassic mass extinction and represent the earliest radiation of Archosauriformes (archosaurs and closely related species). Proterosuchids are potentially represented by approximately 15 nominal species collected from South Africa, China, Russia, Australia and India, but the taxonomic content of the group is currently in a state of flux because of the poor anatomic and systematic information available for several of its putative members. Here, the putative proterosuchid Tasmaniosaurus triassicus from the Lower Triassic of Hobart, Tasmania (Australia),is redescribed. The holotype and currently only known specimen includes cranial and postcranial remains and the revision of this material sheds new light on the anatomy of the animal, including new data on the cranial endocast. Several bones are re-identified or reinterpreted, contrasting with the descriptions of previous authors. The new information provided here shows that Tasmaniosaurus closely resembles the South African proterosuchid Proterosuchus, but it differed in the presence of, for example, a slightly downturned premaxilla, a shorter anterior process of maxilla, and a diamond-shaped anterior end of interclavicle. Previous claims for the presence of gut contents in the holotype of Tasmaniosaurus are considered ambiguous. The description of the cranial endocast of Tasmaniosaurus provides for the first time information about the anatomy of this region in proterosuchids. The cranial endocast preserves possibly part of the vomero-nasal (= Jacobson's) system laterally to the olfactory bulbs. Previous claims of the absence of the vomero-nasal organs in archosaurs, which is suggested by the extant phylogenetic bracket, are questioned because its absence in both clades of extant archosaurs seems to be directly related with the independent acquisition of a non-ground living mode of life
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