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| 2. |
- Iacobelli, M., et al.
(författare)
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Studying Galactic interstellar turbulence through fluctuations in synchrotron emission: First LOFAR Galactic foreground detection
- 2013
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 558, s. 721-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. The characteristic outer scale of turbulence (i.e. the scale at which the dominant source of turbulence injects energy to the interstellar medium) and the ratio of the random to ordered components of the magnetic field are key parameters to characterise magnetic turbulence in the interstellar gas, which affects the propagation of cosmic rays within the Galaxy. We provide new constraints to those two parameters. Methods. We use the LOw Frequency ARray (LOFAR) to image the diffuse continuum emission in the Fan region at (l,b) ∼ (137.0, +7.0) at 80′′ × 70′′ resolution in the range [146, 174] MHz. We detect multi-scale fluctuations in the Galactic synchrotron emission and compute their power spectrum. Applying theoretical estimates and derivations from the literature for the first time, we derive the outer scale of turbulence and the ratio of random to ordered magnetic field from the characteristics of these fluctuations. Results. We obtain the deepest image of the Fan region to date and find diffuse continuum emission within the primary beam. The power spectrum displays a power law behaviour for scales between 100 and 8 arcmin with a slope α =-1.84 ± 0.19. We find an upper limit of ∼20 pc for the outer scale of the magnetic interstellar turbulence toward the Fan region, which is in agreement with previous estimates in literature. We also find a variation of the ratio of random to ordered field as a function of Galactic coordinates, supporting different turbulent regimes. Conclusions. We present the first LOFAR detection and imaging of the Galactic diffuse synchrotron emission around 160 MHz from the highly polarized Fan region. The power spectrum of the foreground synchrotron fluctuations is approximately a power law with a slope α ≈-1.84 up to angular multipoles of ≤1300, corresponding to an angular scale of ∼8 arcmin. We use power spectra fluctuations from LOFAR as well as earlier GMRT and WSRT observations to constrain the outer scale of turbulence (Lout) of the Galactic synchrotron foreground, finding a range of plausible values of 10-20 pc. Then, we use this information to deduce lower limits of the ratio of ordered to random magnetic field strength. These are found to be 0.3, 0.3, and 0.5 for the LOFAR, WSRT and GMRT fields considered respectively. Both these constraints are in agreement with previous estimates. © 2013 ESO.
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- Rana, A., et al.
(författare)
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An edge services framework (esf) for egee, lcg, AND osg
- 2006
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Konferensbidrag (refereegranskat)abstract
- We report on first experiences with building and operating an Edge Services Framework (ESF) based on Xen virtual machines instantiated via the Workspace Service available in Globus Toolkit, and developed as a joint project between EGEE, LCG, and OSG. Many computing facilities are architected with their compute and storage clusters behind firewalls. Edge Services are instantiated on a small set of gateways to provide access to these clusters via standard grid interfaces. Experience on EGEE, LCG, and OSG has shown that at least two issues are of critical importance when designing an infrastructure in support of Edge Services. The first concerns Edge Service configuration. It is impractical to assume that each virtual organization (VO) using a facility will employ the same Edge Service configuration, or that different configurations will coexist easily. Even within a VO, it should be possible to run different versions of the same Edge Service simultaneously. The second issue concerns resource usage: since Edge Services may become a bottleneck to a site, it is essential that an ESF be able to effectively arbitrate resource usage (e.g., memory, CPU, and networking) among different VOs. By providing virtualization on the level of instruction set architecture, virtual machines allow configuration of independent software stacks for each VM executing on a resource. Modern implementations of this abstraction are extremely efficient and have outstanding fine-grained enforcement capabilities. To securely deploy virtual machines, we use the Workspace Service from the Globus Toolkit, which allows a VO administrator to dynamically launch appropriately-configured system images. In addition, we are developing a library of such images, reflecting the needs of presently participating communities ATLAS, CMS, and CDF. We will report on first experiences building and operating this Edge Services Framework.
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- Gourgon, C., et al.
(författare)
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Benchmarking of 50 nm features in thermal nanoimprint
- 2007
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 25:6, s. 2373-2378
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this benchmarking is to establish a comparison of several tools and processes used in thermal NIL with Si stamps at the nanoscale among the authors' laboratories. The Si stamps have large arrays of 50 nm dense lines and were imprinted in all these laboratories in a similar to 100 nm thick mr-18010E film. Other materials, such as mr-17010E, were also tested. Good patterns were obtained and some limitations were identified. Reducing the pressure to 15 bars enables the printing of 50 nm structures without pulling them off. At higher pressures, some bending effects resulting in pattern deformation were observed. It was proven that a pressure of 1.5 bars is sufficient to imprint perfect 50 nm lines. The influence of the antiadhesive layer and mold design has been characterized by the demonstration of pulled off lines in some cases. Moreover, it has been shown that the scatterometry method is particularly useful for the characterization of 50 nm lines and that the residual layer thickness corresponds to the theoretical estimate as long as the lines are well defined. One process was demonstrated which combines high reproducibility with high throughput, achieving a cycle time of 2 min. (c) 2007 American Vacuum Society.
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| 5. |
- Wang, Xin, et al.
(författare)
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Global burden of respiratory infections associated with seasonal influenza in children under 5 years in 2018 : a systematic review and modelling study
- 2020
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Ingår i: The Lancet Global Health. - : Elsevier. - 2214-109X. ; 8:4, s. E497-E510
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Forskningsöversikt (refereegranskat)abstract
- Background: Seasonal influenza virus is a common cause of acute lower respiratory infection (ALRI) in ung children. In 2008, we estimated that 20 million influenza-virus-associated ALRI and 1 million fluenza-virus-associated severe ALRI occurred in children under 5 years globally. Despite this bstantial burden, only a few low-income and middle-income countries have adopted routine influenza ccination policies for children and, where present, these have achieved only low or unknown levels of ccine uptake. Moreover, the influenza burden might have changed due to the emergence and rculation of influenza A/H1N1pdm09. We aimed to incorporate new data to update estimates of the obal number of cases, hospital admissions, and mortality from influenza-virus-associated respiratory fections in children under 5 years in 2018.Methods: We estimated the regional and global burden of influenza-associated respiratory infections in ildren under 5 years from a systematic review of 100 studies published between Jan 1, 1995, and Dec , 2018, and a further 57 high-quality unpublished studies. We adapted the Newcastle-Ottawa Scale to sess the risk of bias. We estimated incidence and hospitalisation rates of influenza-virus-associated spiratory infections by severity, case ascertainment, region, and age. We estimated in-hospital deaths om influenza virus ALRI by combining hospital admissions and in-hospital case-fatality ratios of fluenza virus ALRI. We estimated the upper bound of influenza virus-associated ALRI deaths based on e number of in-hospital deaths, US paediatric influenza-associated death data, and population-based ildhood all-cause pneumonia mortality data in six sites in low-income and lower-middle-income untries.Findings: In 2018, among children under 5 years globally, there were an estimated 109.5 million fluenza virus episodes (uncertainty range [UR] 63.1-190.6), 10.1 million influenza-virus-associated ALRI ses (6.8-15.1); 870 000 influenza-virus-associated ALRI hospital admissions (543 000-1 415 000), 15 300 -hospital deaths (5800-43 800), and up to 34 800 (13 200-97 200) overall influenza-virus-associated ALRI deaths. Influenza virus accounted for 7% of ALRI cases, 5% of ALRI hospital admissions, and 4% of ALRI deaths in children under 5 years. About 23% of the hospital admissions and 36% of the in-hospital deaths were in infants under 6 months. About 82% of the in-hospital deaths occurred in low-income and lower-middle-income countries.Interpretation: A large proportion of the influenza-associated burden occurs among young infants and in low-income and lower middle-income countries. Our findings provide new and important evidence for maternal and paediatric influenza immunisation, and should inform future immunisation policy particularly in low-income and middle-income countries.
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