795 research outputs found
Superconductivity in Sr2RuO4-Sr3Ru2O7 eutectic crystals
Superconducting behavior has been observed in the Sr2RuO4-Sr3Ru2O7 eutectic
system as grown by the flux-feeding floating zone technique. A supercurrent
flows across a single interface between Sr2RuO4 and Sr3Ru2O7 areas at distances
that are far beyond those expected in a conventional proximity scenario. The
current-voltage characteristics within the Sr3Ru2O7 macrodomain, as extracted
from the eutectic, exhibit signatures of superconductivity in the bilayered
ruthenate. Detailed microstructural, morphological and compositional analyses
address issues on the concentration and the size of Sr2RuO4 inclusions within
the Sr3Ru2O7 matrix. We speculate on the possibility of inhomogeneous
superconductivity in the eutectic Sr3Ru2O7 and exotic pairing induced by the
Sr2RuO4 inclusions.Comment: Pages 4, figures 3, submitted to Phys. Rev. Let
Mission and Design Sensitivities for Human Mars Landers Using Hypersonic Inflatable Aerodynamic Decelerators
Landing humans on Mars is one of NASA's long term goals. NASA's Evolvable Mars Campaign (EMC) is focused on evaluating architectural trade options to define the capabilities and elements needed to sustain human presence on the surface of Mars. The EMC study teams have considered a variety of in-space propulsion options and surface mission options. Understanding how these choices affect the performance of the lander will allow a balanced optimization of this complex system of systems problem. This paper presents the effects of mission and vehicle design options on lander mass and performance. Beginning with Earth launch, options include fairing size assumptions, co-manifesting elements with the lander, and Earth-Moon vicinity operations. Capturing into Mars orbit using either aerocapture or propulsive capture is assessed. For entry, descent, and landing both storable as well as oxygen and methane propellant combinations are considered, engine thrust level is assessed, and sensitivity to landed payload mass is presented. This paper focuses on lander designs using the Hypersonic Inflatable Aerodynamic Decelerators, one of several entry system technologies currently considered for human missions
I-Move towards monitoring seasonal and pandemic influenza vaccine effectiveness: lessons learnt from a pilot multi-centric case-control study in europe, 2008-9
Within I-MOVE (European programme to monitor seasonal and pandemic influenza vaccine effectiveness (IVE)) five countries conducted IVE pilot case-control studies in 2008-9. One hundred and sixty sentinel general practitioners (GP) swabbed all elderly consulting for influenza-like illness (ILI). Influenza confirmed cases were compared to influenza negative controls. We conducted a pooled analysis to obtain a summary IVE in the age group of >or=65 years. We measured IVE in each study and assessed heterogeneity between studies qualitatively and using the I2 index. We used a one-stage pooled model with study as a fixed effect. We adjusted estimates for age-group, sex, chronic diseases, smoking, functional status, previous influenza vaccinations and previous hospitalisations. The pooled analysis included 138 cases and 189 test-negative controls. There was no statistical heterogeneity (I2=0) between studies but ILI case definition, previous hospitalisations and functional status were slightly different. The adjusted IVE was 59.1% (95% CI: 15.3-80.3%). IVE was 65.4% (95% CI: 15.6-85.8%) in the 65-74, 59.6% (95% CI: -72.6 -90.6%) in the age group of >or=75 and 56.4% (95% CI: -0.2-81.3%) for A(H3). Pooled analysis is feasible among European studies. The variables definitions need further standardisation. Larger sample sizes are needed to achieve greater precision for subgroup analysis. For 2009-10, I-MOVE will extend the study to obtain early IVE estimates in groups targeted for pandemic H1N1 influenza vaccination.European Centre for Disease Prevention and Control (ECDC
Wider implications of video-assisted thoracic surgery versus open approach for lung metastasectomy
Lung metastasectomy is considered a safe and potentially curative procedure
despite there is not a strong evidence that metastasectomy prolongs long-term survival in
patients with lung metastases. Moreover, the debate is open regarding the best approach for
lung metastasectomy, video-assisted thoracic surgery versus open approach. A systematic
review of literature to clarify what is the best approach to prolong survival in patients with
lung metastases was performed. Our study confirms that overall survival is equivalent for
video-assisted thoracic surgery and thoracotomy, therefore the ‘gold standard’ surgical
treatment for lung metastases remains a point of debate. The choice of the surgical approach
still depends more on the single center or surgeon practice than on strong scientific evidence.
A prospective randomized trial could clarify the question
Effect of microstructure on heat transfer through compacted cement-stabilised soils
Recent work has identified that the compaction of cement-stabilised soils at water contents above and below their optimum value significantly affects material strength due to the creation of contrasting microstructures. Besides strength, however, it is also likely that these materials will have different thermal properties, due to the different arrangement of particles and aggregates. These differences cannot be predicted by current methods due to their reliance on material phase volume fractions, rather than distributions. This is of particular importance to the Rammed Earth (RE) construction industry, a popular form of environmentally-friendly construction in Australia. RE is currently penalised under Australian building regulations due to its apparently-poor thermal properties. The ability to engineer, or at least better predict, the thermal properties of these materials will therefore be of significant benefit.This paper presents results for the development and validation of the experimental equipment and procedures necessary to determine the thermal properties of Cement-Stabilised RE (CSRE) materials. The development of sensors able to be incorporated into CSRE materials is discussed and two installation methods - embedding and drilling-and-grouting - are investigated using specimens of constant microstructure as confirmed via Scanning Electron Microscope (SEM) analysis. Results show that preparation techniques were able to produce consistent microstructures and that little difference is found between calculated thermal properties (thermal resistance and specific heat capacity) for either installation technique. However, calculated thermal properties differ significantly from those found by previous authors. Further testing will therefore be conducted to investigate this shortfall, prior to the extension of this work to additional materials and microstructures.</p
Outlining multi-purpose forest inventories to assess the ecosystem approach in forestry
A summary and discussion of selected published results on the current and potential role of forest inventories (with particular
reference to the national ones) are presented in the light of the challenges posed by society and policy decisions in the
environmental sector. The analysis concentrates mainly on the ecological and socio-economic aspects of the question and on
forest inventories’ potential contribution to achieving sustainable forest management.L'articolo è diponibile sul sito dell'editore wwww.tandf.co.uk/journals
Low and decreasing vaccine effectiveness against influenza A(H3) in 2011/12 among vaccination target groups in Europe: results from the I-MOVE multicentre case-control study
Within the Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) project we conducted a multicentre case–control study in eight European Union (EU) Member States to estimate the 2011/12 influenza vaccine effectiveness against medically attended influenza-like illness (ILI) laboratory-confirmed as influenza A(H3) among the vaccination target groups. Practitioners systematically selected ILI / acute respiratory infection patients to swab within seven days of symptom onset. We restricted the study population to those meeting the EU ILI case definition and compared influenza A(H3) positive to influenza laboratory-negative patients. We used logistic regression with study site as fixed effect and calculated adjusted influenza vaccine effectiveness (IVE), controlling for potential confounders (age group, sex, month of symptom onset, chronic diseases and related hospitalisations, number of practitioner visits in the previous year). Adjusted IVE was 25% (95% confidence intervals (CI): -6 to 47) among all ages (n=1,014), 63% (95% CI: 26 to 82) in adults aged between 15 and 59 years and 15% (95% CI: -33 to 46) among those aged 60 years and above. Adjusted IVE was 38% (95%CI: -8 to 65) in the early influenza season (up to week 6 of 2012) and -1% (95% CI: -60 to 37) in the late phase. The results suggested a low adjusted IVE in 2011/12. The lower IVE in the late season could be due to virus changes through the season or waning immunity. Virological surveillance should be enhanced to quantify change over time and understand its relation with duration of immunological protection. Seasonal influenza vaccines should be improved to achieve acceptable levels of protection.ECD
HBV quasispecies composition in Lamivudine-failed chronic hepatitis B patients and its influence on virological response to Tenofovir-based rescue therapy
The present study sought to evaluate the structure of HBV quasispecies in Lamivudine (LMV)-failed chronic hepatitis B (CHB) patients and its impact in defining the subsequent virological responses to Tenofovir (TDF)-based rescue-therapy. By analyzing HBV clones encompassing reverse transcriptase (RT) and surface (S) region from LMV-failed and treatment-naïve CHB patients, we identified 5 classical and 12 novel substitutions in HBV/RT and 9 substitutions in immune-epitopes of HBV/S that were significantly associated with LMV failure. In silico analysis showed spatial proximity of some of the newly-identified, mutated RT residues to the RT catalytic centre while most S-substitutions caused alteration in epitope hydrophobicity. TDF administration resulted in virological response in 60% of LMV-failed patients at 24-week but non-response in 40% of patients even after 48-weeks. Significantly high frequencies of 6 S-substitutions and one novel RT-substitution, rtH124N with 6.5-fold-reduced susceptibility to TDF in vitro, were noted at baseline in TDF non-responders than responders. Follow-up studies depicted greater evolutionary drift of HBV quasispecies and significant decline in frequencies of 3 RT and 6 S-substitutions in responder-subgroup after 24-week TDF-therapy while most variants persisted in non-responders. Thus, we identified the HBV-RT/S variants that could potentially predict unfavorable response to LMV/TDF-therapy and impede immune-mediated viral clearance
A review of the contribution of thermal mass to thermal comfort in rammed earth structures
Rammed earth is a construction material which has been used to build thermally-comfortable structures in many regions around the world for thousands of years. Despite this heritage, rammed earth is currently considered to be unsuitable for construction by many green-building guidelines due to its low thermal resistance, a property deemed to be necessary if a structure is to reduce its heating and cooling demand. This paper introduces thermal comfort and relates it to thermal resistance and thermal mass. A review of previous work which has investigated thermal comfort in rammed earth structures is then presented. Techniques used to adapt the designs of traditional rammed earth structures to suit their prevalent climate are then briefly discussed and compared to modern construction practices in similar regions to suggest methods by which the thermal comfort and sustainability of modern structures can be improved
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