620 research outputs found
Damage in the Cadalso de los Vidrios Granite under water freeze/thaw conditions
The repeated action of simulated freeze-thaw cycles on Cadalso de los Vidrios Granite, promotes
differential micro-cracking and loss of cr ystals at the surface and therefore decay. It is possible to
establish a relationship between the evolution of the ultrasound waves velocity (Vp) with the number
of freeze-thaw cycles and the generation of microcracks. Intergranular cracks are formed during the
first cycles and these propagate towards the inner part of each individual crystals as the freeze-thaw
cycles advance. Therefore, after 280 freeze-thaw cycles different patterns of microcracking can be
observed depending on the mineralogy. Quartz is the mineral displaying more intense cracking while
biotite shows less cracking, in part due to its more ductile behaviour. Micro-cracks appear preferentially
at the surface of the samples with a maximum length and depth of 1 cm. Thus, these samples showed
limited decay highlighting the good performance of Cadalso de los Vidrios granite against freezethaw.Peer reviewe
Rare-earth-activated glasses for solar energy conversion
The solar cells efficiency may be improved by better exploitation of the solar spectrum, making use of the down-conversion mechanism, where one high energy photon is cut into two low energy photons. The choice of the matrix is a crucial point to obtain an efficient down-conversion process with rare-earth ions. When energy transfer between rare earth ions is used to activate this process, high emission and absorption cross sections as well as low cut-off phonon energy are mandatory. In this paper we present some results concerning 70SiO2-30HfO2 glass ceramic planar waveguides co-activated by Tb3+/Yb3+ ions, fabricated by sol gel route using a top-down approach, and a bulk fluoride glass of molar composition 70ZrF4 23.5LaF3 0.5AlF3 6GaF3 co-activated by Pr3+/Yb3+ ion. Attention is focused on the assessment of the energy transfer efficiency between the two couples of rare earth ions in the different hosts
Simulating crowd evacuation with socio-cultural, cognitive, and emotional elements
In this research, the effects of culture, cognitions, and emotions on crisis management and prevention are analysed. An agent-based crowd evacuation simulation model was created, named IMPACT, to study the evacuation process from a transport hub. To extend previous research, various socio-cultural, cognitive, and emotional factors were modelled, including: language, gender, familiarity with the environment, emotional contagion, prosocial behaviour, falls, group decision making, and compliance. The IMPACT model was validated against data from an evacuation drill using the existing EXODUS evacuation model. Results show that on all measures, the IMPACT model is within or close to the prescribed boundaries, thereby establishing its validity. Structured simulations with the validated model revealed important findings, including: the effect of doors as bottlenecks, social contagion speeding up evacuation time, falling behaviour not affecting evacuation time significantly, and travelling in groups being more beneficial for evacuation time than travelling alone. This research has important practical applications for crowd management professionals, including transport hub operators, first responders, and risk assessors
Anisotropy effects on the plasmonic response of nanoparticle dimers
We present an ab initio study of the anisotropy and atomic relaxation effects on the optical properties of nanoparticle dimers. Special emphasis is placed on the hybridization process of localized surface plasmons, plasmon-mediated photoinduced currents, and electric-field enhancement in the dimer junction. We show that there is a critical range of separations between the clusters (0.1–0.5 nm) in which the detailed atomic structure in the junction and the relative orientation of the nanoparticles have to be considered to obtain quantitative predictions for realistic nanoplasmonic devices. It is worth noting that this regime is characterized by the emergence of electron tunneling as a response to the driven electromagnetic field. The orientation of the particles not only modifies the attainable electric field enhancement but can lead to qualitative changes in the optical absorption spectrum of the system.We thankfully acknowledge financial support by the European Research Council (ERC-2010-AdG Proposal No. 267374 and ERC-2011-AdG Proposal No. 290891), the Spanish Government (Grants MAT2011-28581-C02-01, FIS2013-46159-C3-1-P, and MAT2014-53432-C5-5-R), and the Basque Country Government (Grupos Consolidados IT-578-13).Peer Reviewe
Modulation of 11β-hydroxysteroid dehydrogenase as a strategy to reduce vascular inflammation
Atherosclerosis is a chronic inflammatory disease in which initial vascular damage leads to extensive macrophage and lymphocyte infiltration. Although acutely glucocorticoids suppress inflammation, chronic glucocorticoid excess worsens atherosclerosis, possibly by exacerbating systemic cardiovascular risk factors. However, glucocorticoid action within the lesion may reduce neointimal proliferation and inflammation. Glucocorticoid levels within cells do not necessarily reflect circulating levels due to pre-receptor metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSDs). 11β-HSD2 converts active glucocorticoids into inert 11-keto forms. 11β-HSD1 catalyses the reverse reaction, regenerating active glucocorticoids. 11β-HSD2-deficiency/ inhibition causes hypertension, whereas deficiency/ inhibition of 11β-HSD1 generates a cardioprotective lipid profile and improves glycemic control. Importantly, 11β-HSD1-deficiency/ inhibition is atheroprotective, whereas 11β-HSD2-deficiency accelerates atherosclerosis. These effects are largely independent of systemic risk factors, reflecting modulation of glucocorticoid action and inflammation within the vasculature. Here, we consider whether evidence linking the 11β-HSDs to vascular inflammation suggests these isozymes are potential therapeutic targets in vascular injury and atherosclerosis
SiO Outflows in the Most Luminous and Massive Protostellar Sources of the Southern Sky
(Abridged) High-mass star formation is far less understood than low-mass star
formation. It entails molecular outflows, which disturb the protostellar clump.
Studying these outflows and the shocked gas they cause is key for a better
understanding of this process. This study aims to characterise the behaviour of
molecular outflows in the most massive protostellar sources in the Southern
Galaxy by looking for evolutionary trends and associating shocked gas with
outflow activity. We present APEX SEPIA180 observations (beamwidth 36")
of SiO outflow candidates of a sample of 32 luminous and dense clumps,
candidates to harbouring Hot Molecular Cores. We study the SiO(4-3) line
emission, an unambiguous tracer of shocked gas and recent outflow activity, the
HCO(2-1) and HCO(2-1) lines. 78% of our sample present SiO
emission. Nine of these also have wings in the HCO line, indicating outflow
activity. The SiO emission of these 9 sources is more intense and wider than
the rest, suggesting that the outflows in this group are faster and more
energetic. Three positive correlations between the outflow properties were
found, which suggest that more energetic outflows bear to mobilise more
material. No correlation was found between the evolutionary stage indicator
and SiO outflow properties, supporting that outflows happen throughout
the whole high-mass star formation process. We conclude that sources with both
SiO emission and HCO wings and sources with only SiO emission are in
virtually the same advanced stage of evolution in the high-mass star formation
process. The former present more massive and more powerful SiO outflows than
the latter. Thus, looking for more outflow signatures such as HCO wings
could help identify more massive and active massive star-forming regions in
samples of similarly evolved sources, as well as sources with older outflow
activity.Comment: 24 pages, 37 figures, 11 table
High quality factor 1-D Er 3+ -activated dielectric microcavity fabricated by RF-sputtering
Rare earth-activated 1-D photonic crystals were fabricated by RF-sputtering technique. The cavity is constituted by an Er3+-doped SiO2 active layer inserted between two Bragg reflectors consisting of ten pairs of SiO2/TiO2 layers. Scanning electron microscopy is employed to put in evidence the quality of the sample, the homogeneities of the layers thickness and the good adhesion among them. Near infrared transmittance and variable angle reflectance spectra confirm the presence of a stop band from 1500 nm to 2000 nm with a cavity resonance centered at 1749 nm at 0° and a quality factor of 890. The influence of the cavity on the 4I13/2 -> 4I15/2 emission band of Er3+ ion is also demonstrated
P-T conditions of crystallization of Mafic Microgranular enclaves from the Illapel Plutonic Complex [IPC]
Mechanisms of Hearing Loss after Blast Injury to the Ear
Given the frequent use of improvised explosive devices (IEDs) around the world, the study of traumatic blast injuries is of
increasing interest. The ear is the most common organ affected by blast injury because it is the bodyメs most sensitive
pressure transducer. We fabricated a blast chamber to re-create blast profiles similar to that of IEDs and used it to develop a
reproducible mouse model to study blast-induced hearing loss. The tympanic membrane was perforated in all mice after
blast exposure and found to heal spontaneously. Micro-computed tomography demonstrated no evidence for middle ear or
otic capsule injuries; however, the healed tympanic membrane was thickened. Auditory brainstem response and distortion
product otoacoustic emission threshold shifts were found to be correlated with blast intensity. As well, these threshold
shifts were larger than those found in control mice that underwent surgical perforation of their tympanic membranes,
indicating cochlear trauma. Histological studies one week and three months after the blast demonstrated no disruption or
damage to the intra-cochlear membranes. However, there was loss of outer hair cells (OHCs) within the basal turn of the
cochlea and decreased spiral ganglion neurons (SGNs) and afferent nerve synapses. Using our mouse model that
recapitulates human IED exposure, our results identify that the mechanisms underlying blast-induced hearing loss does not
include gross membranous rupture as is commonly believed. Instead, there is both OHC and SGN loss that produce auditory
dysfunction
A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)
Meeting abstrac
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