856 research outputs found
Quantum states made to measure
Recent progress in manipulating quantum states of light and matter brings
quantum-enhanced measurements closer to prospective applications. The current
challenge is to make quantum metrologic strategies robust against
imperfections.Comment: 4 pages, 3 figures, Commentary for Nature Photonic
Image Analysis Enhanced Event Detection from Geo-tagged Tweet Streams
Events detected from social media streams often include early signs of
accidents, crimes or disasters. Therefore, they can be used by related parties
for timely and efficient response. Although significant progress has been made
on event detection from tweet streams, most existing methods have not
considered the posted images in tweets, which provide richer information than
the text, and potentially can be a reliable indicator of whether an event
occurs or not. In this paper, we design an event detection algorithm that
combines textual, statistical and image information, following an unsupervised
machine learning approach. Specifically, the algorithm starts with semantic and
statistical analyses to obtain a list of tweet clusters, each of which
corresponds to an event candidate, and then performs image analysis to separate
events from non-events---a convolutional autoencoder is trained for each
cluster as an anomaly detector, where a part of the images are used as the
training data and the remaining images are used as the test instances. Our
experiments on multiple datasets verify that when an event occurs, the mean
reconstruction errors of the training and test images are much closer, compared
with the case where the candidate is a non-event cluster. Based on this
finding, the algorithm rejects a candidate if the difference is larger than a
threshold. Experimental results over millions of tweets demonstrate that this
image analysis enhanced approach can significantly increase the precision with
minimum impact on the recall.Comment: 12 pages, 4 figure
Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?
Background: Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties. Nevertheless, it was proven that, due to modest dispersion of nanoparticles, such high expectations often remain unmet. In this article, by introducing the notion of nanofin, a possible solution is envisioned, where nanostructures with high aspect-ratio are sparsely attached to a solid surface (to avoid a significant disturbance on the fluid dynamic structures), and act as efficient thermal bridges within the boundary layer. As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes. Results: Toward the end of implementing the above idea, we focus on single carbon nanotubes to enhance heat transfer between a surface and a fluid in contact with it. First, we investigate the thermal conductivity of the latter nanostructures by means of classical non-equilibrium molecular dynamics simulations. Next, thermal conductance at the interface between a single wall carbon nanotube (nanofin) and water molecules is assessed by means of both steady-state and transient numerical experiments. Conclusions: Numerical evidences suggest a pretty favorable thermal boundary conductance (order of 107 WΒ·m-2Β·K-1) which makes carbon nanotubes potential candidates for constructing nanofinned surface
Pull-out and push-in tests of bonded steel strands
MartΓ Vargas, JR. (2013). Pull-out and push-in tests of bonded steel strands. Magazine of Concrete Research. 65(18):1128-1131. doi:10.1680/macr.13.00061S112811316518BalΓ‘zs LG .Bond Model with Non-Linear Bond-Slip Law, 1987, Politecnico di Milano, Italy, 395β430, Studi e Ricerche, Post-Graduate Course for Reinforced Concrete Structures, V.8/86.Balazs, G. L. (1992). Transfer Control of Prestressing Strands. PCI Journal, 37(6), 60-71. doi:10.15554/pcij.11011992.60.71Balazs, G. L. (1993). Transfer Length of Prestressing Strand as a Function of Draw-In and Initial Prestress. PCI Journal, 38(2), 86-93. doi:10.15554/pcij.03011993.86.93BalΓ‘zs, G. L. (2007). Connecting Reinforcement to Concrete by Bond. Beton- und Stahlbetonbau, 102(S1), 46-50. doi:10.1002/best.200710109Carmo RNF .Ancoragem de Armaduras PrΓ©-EsforΓ§adas por PrΓ©-TensΓ£o. MSc thesis, 1999, Faculdade de CiΓͺncias e Tecnologia, Universidade de Coimbra, Portugal, (in Portuguese).Faria, D. M. V., LΓΊcio, V. J. G., & Pinho Ramos, A. (2011). Pull-out and push-in tests of bonded steel strands. Magazine of Concrete Research, 63(9), 689-705. doi:10.1680/macr.2011.63.9.689Faria, D. M. V., LΓΊcio, V. J. G., & Ramos, A. P. (2011). Strengthening of flat slabs with post-tensioning using anchorages by bonding. Engineering Structures, 33(6), 2025-2043. doi:10.1016/j.engstruct.2011.02.039Faria, D. M. V., LΓΊcio, V. J. G., & Pinho Ramos, A. (2012). Post-punching behaviour of flat slabs strengthened with a new technique using post-tensioning. Engineering Structures, 40, 383-397. doi:10.1016/j.engstruct.2012.03.014Laldji S .Bond Characteristics of Prestressing Strand in Grout. MPhil thesis, 1987, University of Leicester, UK.Laldji, S., & Young, A. G. (1988). Bond between steel strand and cement grout in ground anchorages. Magazine of Concrete Research, 40(143), 90-98. doi:10.1680/macr.1988.40.143.90Lopes, S. M. R., & do Carmo, R. N. F. (2002). Bond of prestressed strands to concrete: transfer rate and relationship between transmission length and tendon draw-in. Structural Concrete, 3(3), 117-126. doi:10.1680/stco.2002.3.3.117MartΓ-Vargas, J. R., Serna-Ros, P., FernΓ‘ndez-Prada, M. A., Miguel-Sosa, P. F., & ArbelΓ‘ez, C. A. (2006). Test method for determination of the transmission and anchorage lengths in prestressed reinforcement. Magazine of Concrete Research, 58(1), 21-29. doi:10.1680/macr.2006.58.1.21Marti-Vargas, J. R., Arbelaez, C. A., Serna-Ros, P., Navarro-Gregori, J., & Pallares-Rubio, L. (2007). Analytical model for transfer length prediction of 13 mm prestressing strand. Structural Engineering and Mechanics, 26(2), 211-229. doi:10.12989/sem.2007.26.2.211Palmer, K. D., & Schultz, A. E. (2011). Experimental investigation of the web-shear strength of deep hollow-core units. PCI Journal, 56(4), 83-104. doi:10.15554/pcij.09012011.83.10
Angiotensin-(1β7) and the G Protein-Coupled Receptor Mas Are Key Players in Renal Inflammation
Angiotensin (Ang) II mediates pathophysiologial changes in the kidney. Ang-(1β7) by interacting with the G protein-coupled receptor Mas may also have important biological activities
Winter Bird Assemblages in Rural and Urban Environments: A National Survey
Urban development has a marked effect on the ecological and behavioural traits of many living
organisms, including birds. In this paper, we analysed differences in the numbers of wintering
birds between rural and urban areas in Poland. We also analysed species richness
and abundance in relation to longitude, latitude, human population size, and landscape
structure. All these parameters were analysed using modern statistical techniques incorporating
species detectability. We counted birds in 156 squares (0.25 km2 each) in December
2012 and again in January 2013 in locations in and around 26 urban areas across Poland
(in each urban area we surveyed 3 squares and 3 squares in nearby rural areas). The influence
of twelve potential environmental variables on species abundance and richness was
assessed with Generalized Linear Mixed Models, Principal Components and Detrended
Correspondence Analyses. Totals of 72 bird species and 89,710 individual birds were recorded
in this study. On average (Β±SE) 13.3 Β± 0.3 species and 288 Β± 14 individuals were recorded
in each square in each survey. A formal comparison of rural and urban areas
revealed that 27 species had a significant preference; 17 to rural areas and 10 to urban areas. Moreover, overall abundance in urban areas was more than double that of rural
areas. There was almost a complete separation of rural and urban bird communities. Significantly
more birds and more bird species were recorded in January compared to December.
We conclude that differences between rural and urban areas in terms of winter conditions
and the availability of resources are reflected in different bird communities in the two
environments
Updating known distribution models for forecasting climate change impact on endangered species
To plan endangered species conservation and to design adequate management programmes, it is necessary to predict their
distributional response to climate change, especially under the current situation of rapid change. However, these
predictions are customarily done by relating de novo the distribution of the species with climatic conditions with no regard
of previously available knowledge about the factors affecting the species distribution. We propose to take advantage of
known species distribution models, but proceeding to update them with the variables yielded by climatic models before
projecting them to the future. To exemplify our proposal, the availability of suitable habitat across Spain for the endangered
Bonelliβs Eagle (Aquila fasciata) was modelled by updating a pre-existing model based on current climate and topography to
a combination of different general circulation models and Special Report on Emissions Scenarios. Our results suggested that
the main threat for this endangered species would not be climate change, since all forecasting models show that its
distribution will be maintained and increased in mainland Spain for all the XXI century. We remark on the importance of
linking conservation biology with distribution modelling by updating existing models, frequently available for endangered
species, considering all the known factors conditioning the speciesβ distribution, instead of building new models that are
based on climate change variables only.Ministerio de Ciencia e InnovaciΓ³n and FEDER (project CGL2009-11316/BOS
Regulatory T Cell Induction during Plasmodium chabaudi Infection Modifies the Clinical Course of Experimental Autoimmune Encephalomyelitis
BACKGROUND: Experimental autoimmune encephalomyelitis (EAE) is used as an animal model for human multiple sclerosis (MS), which is an inflammatory demyelinating autoimmune disease of the central nervous system characterized by activation of Th1 and/or Th17 cells. Human autoimmune diseases can be either exacerbated or suppressed by infectious agents. Recent studies have shown that regulatory T cells play a crucial role in the escape mechanism of Plasmodium spp. both in humans and in experimental models. These cells suppress the Th1 response against the parasite and prevent its elimination. Regulatory T cells have been largely associated with protection or amelioration in several autoimmune diseases, mainly by their capacity to suppress proinflammatory response. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we verified that CD4(+)CD25(+) regulatory T cells (T regs) generated during malaria infection (6 days after EAE induction) interfere with the evolution of EAE. We observed a positive correlation between the reduction of EAE clinical symptoms and an increase of parasitemia levels. Suppression of the disease was also accompanied by a decrease in the expression of IL-17 and IFN-Ξ³ and increases in the expression of IL-10 and TGF-Ξ²1 relative to EAE control mice. The adoptive transfer of CD4(+)CD25(+) cells from P. chabaudi-infected mice reduced the clinical evolution of EAE, confirming the role of these T regs. CONCLUSIONS/SIGNIFICANCE: These data corroborate previous findings showing that infections interfere with the prevalence and evolution of autoimmune diseases by inducing regulatory T cells, which regulate EAE in an apparently non-specific manner
Small but crucial : the novel small heat shock protein Hsp21 mediates stress adaptation and virulence in Candida albicans
Peer reviewedPublisher PD
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