892 research outputs found
An analysis of the elastic properties of a porous aluminium oxide film by means of indentation techniques
The elastic modulus of thin films can be directly determined by instrumented indentation when the indenter penetration does not exceed a fraction of the film thickness, depending on the mechanical properties of both film and substrate. When it is not possible, application of models for separating the contribution of the substrate is necessary. In this work, the robustness of several models is analyzed in the case of the elastic modulus determination of a porous aluminium oxide film produced by anodization of an aluminium alloy. Instrumented indentation tests employing a Berkovich indenter were performe data nanometric scale, which allowed a direct determination of the film elastic modulus, whose value was found to be approximately 11 GPa. However, at a micrometric scale the elastic modulus tends toward the value corresponding to the substrate, of approximately 73 GPa. The objective of the present work is to apply different models for testing their consistency over the complete set of indentation data obtained from both classical tests in microindentation and the continuous stiffness measurement mode in nanoindentation. This approach shows the continuity between the two scales of measurement thus allowing a better representation of the elastic modulus variation between two limits corresponding to the substrate and film elastic moduli. Gao's function proved to be the best to represen the elastic modulus variation
Discovery and partial genomic characterisation of a novel nidovirus associated with respiratory disease in wild shingleback lizards (Tiliqua rugosa)
A respiratory disease syndrome has been observed in large numbers of wild shingleback lizards (Tiliqua rugosa) admitted to wildlife care facilities in the Perth metropolitan region of Western Australia. Mortality rates are reportedly high without supportive treatment and care. Here we used next generation sequencing techniques to screen affected and unaffected individuals admitted to Kanyana Wildlife Rehabilitation Centre in Perth between April and December 2015, with the resultant discovery of a novel nidovirus significantly associated with cases of respiratory disease according to a case definition based on clinical signs. Interestingly this virus was also found in 12% of apparently healthy individuals, which may reflect testing during the incubation period or a carrier status, or it may be that this agent is not causative in the disease process. This is the first report of a nidovirus in lizards globally. In addition to detection of this virus, characterisation of a 23,832 nt segment of the viral genome revealed the presence of characteristic nidoviral genomic elements providing phylogenetic support for the inclusion of this virus in a novel genus alongside Ball Python nidovirus, within the Torovirinae sub-family of the Coronaviridae. This study highlights the importance of next generation sequencing technologies to detect and describe emerging infectious diseases in wildlife species, as well as the importance of rehabilitation centres to enhance early detection mechanisms through passive and targeted health surveillance. Further development of diagnostic tools from these findings will aid in detection and control of this agent across Australia, and potentially in wild lizard populations globally
Chlamydia trachomatis prevents apoptosis via activation of PDPK1-MYC and enhanced mitochondrial binding of hexokinase II
The intracellular human bacterial pathogen Chlamydia trachomatis pursues effective strategies to protect infected cells against death-inducing stimuli. Here, we show that Chlamydia trachomatis infection evokes 3-phosphoinositide-dependent protein kinase-1 (PDPK1) signaling to ensure the completion of its developmental cycle, further leading to the phosphorylation and stabilization of MYC. Using biochemical approaches and imaging we demonstrate that Chlamydia-induced PDPK1-MYC signaling induces host hexokinase II (HKII), which becomes enriched and translocated to the mitochondria. Strikingly, preventing the HKII interaction with mitochondria using exogenous peptides triggers apoptosis of infected cells as does inhibiting either PDPK1 or MYC, which also disrupts intracellular development of Chlamydia trachomatis. These findings identify a previously unknown pathway activated by Chlamydia infection, which exhibits pro-carcinogenic features. Targeting the PDPK1-MYC-HKII-axis may provide a strategy to overcome therapeutic resistance of infection
Unlocking the mystery of the mid‑Cretaceous Mysteriomorphidae (Coleoptera: Elateroidea) and modalities in transiting from gymnosperms to angiosperms
The monospecific family Mysteriomorphidae was recently described based on two fossil specimens from the Late Cretaceous Kachin amber of northern Myanmar. The family was placed in Elateriformia incertae sedis without a clear list of characters that define it either in Elateroidea or in Byrrhoidea. We report here four additional adult specimens of the same lineage, one of which was described using a successful reconstruction from a CT-scan analysis to better observe some characters. The new specimens enabled us to considerably improve the diagnosis of Mysteriomorphidae. The family is definitively placed in Elateroidea, and we hypothesize its close relationship with Elateridae. Similarly, there are other fossil families of beetles that are exclusively described from Cretaceous ambers. These lineages may have been evolutionarily replaced by the ecological revolution launched by angiosperms that introduced new co-associations with taxa. These data indicate a macroevolutionary pattern of replacement that could be extended to other insect groups
Spin three gauge theory revisited
We study the problem of consistent interactions for spin-3 gauge fields in
flat spacetime of arbitrary dimension n>3. Under the sole assumptions of
Poincar\'e and parity invariance, local and perturbative deformation of the
free theory, we determine all nontrivial consistent deformations of the abelian
gauge algebra and classify the corresponding deformations of the quadratic
action, at first order in the deformation parameter. We prove that all such
vertices are cubic, contain a total of either three or five derivatives and are
uniquely characterized by a rank-three constant tensor (an internal algebra
structure constant). The covariant cubic vertex containing three derivatives is
the vertex discovered by Berends, Burgers and van Dam, which however leads to
inconsistencies at second order in the deformation parameter. In dimensions n>4
and for a completely antisymmetric structure constant tensor, another covariant
cubic vertex exists, which contains five derivatives and passes the consistency
test where the previous vertex failed.Comment: LaTeX, 37 pages. References and comments added. Published versio
Dynamics of Higher Spin Fields and Tensorial Space
The structure and the dynamics of massless higher spin fields in various
dimensions are reviewed with an emphasis on conformally invariant higher spin
fields. We show that in D=3,4,6 and 10 dimensional space-time the conformal
higher spin fields constitute the quantum spectrum of a twistor-like particle
propagating in tensorial spaces of corresponding dimensions. We give a detailed
analysis of the field equations of the model and establish their relation with
known formulations of free higher spin field theory.Comment: JHEP3 style, 40 pages; v2 typos corrected, comments and references
added; v3 published versio
Intensity-fading and other MS approaches to analyze proteases and protease in inhibitors and their interactions in biological samples
Comunicaciones a congreso
Geology and paleontology of Tresjuncos (Cuenca, Spain), a new diatomaceous deposit with Konservat-Lagerstätte characteristics from the European late Miocene.
Purpose A new Iberian Konservat-Lagersta¨tte discovered in Tresjuncos (Cuenca, Spain) is described and interpreted based on geological and paleontological information. Methods The samples were studied using conventional mineralogical (powder X-ray diffraction), petrographic (optical and scanning electron microscopy) and geochemical (X-ray energy-dispersive spectrometry) techniques. Results Based upon geological context, stratigraphy, lithology, sedimentology and origin of the rocks, we describe and interpret the new fossil site as originated in a lacustrine environment. The micromammals found in the Tresjuncos 1 outcrop suggest that the main site is Turolian in age (uppermost Miocene), continental chronological unit MN13. The fossils are preserved in laminates comprising rhythmic, millimeterscale alternations of diatomites and calcareous diatomites. An analysis of the lake paleobiota includes amphibians, crustaceans, insects, plants, and diatoms. The diatoms are dominated by Cyclotella iris. The whole assemblage is indicative of a planktic community developed in somewhat alkaline waters. An extremely well preserved premetamorphic Pelobates (Pelobatidae) tadpole was discovered; it is remarkable because of its gigantic size. Its digestive tract predominantly contains the rare diatom Navicula halionata var directa, likely associated with the shore vegetation in which it presumably lived and fed. The arthropods form a typical lacustrine aquatic assemblage, lacking fish. This assemblage is made up of small filtering crustaceans and of both predator and nonpredator insects of diverse sizes. Conclusions The available evidence on Tresjuncos shows the extraordinary potential for paleontological information that can be expected from this new Konservat-Lagersta¨tte, which constitutes a significant finding that improves our understanding of continental late Miocene Mediterranean environments
Gravitational Wave Bursts from Cosmic Superstring Reconnections
We compute the gravitational waveform produced by cosmic superstring
reconnections. This is done by first constructing the superstring reconnection
trajectory, which closely resembles that of classical, instantaneous
reconnection but with the singularities smoothed out due to the string path
integral. We then evaluate the graviton vertex operator in this background to
obtain the burst amplitude. The result is compared to the detection threshold
for current and future gravitational wave detectors, finding that neither
bursts nor the stochastic background would be detectable by Advanced LIGO. This
disappointing but anticipated conclusion holds even for the most optimistic
values of the reconnection probability and loop sizes.Comment: 26 pages, 6 figures; v2: references added and typos correcte
Raman Spectroscopy Studies on the Barocaloric Hybrid Perovskite [(CH₃)₄N][Cd(N₃)₃]
[Abstract] Temperature-dependent Raman scattering and differential scanning calorimetry were applied to the study of the hybrid organic-inorganic azide-perovskite [(CH₃)₄N][Cd(N₃)₃], a compound with multiple structural phase transitions as a function of temperature. A significant entropy variation was observed associated to such phase transitions, |∆S| ~ 62.09 J·kg⁻¹ K⁻¹, together with both a positive high barocaloric (BC) coefficient |δTt/δP| ~ 12.39 K kbar⁻¹ and an inverse barocaloric (BC) coefficient |δTt/δP| ~ −6.52 kbar⁻¹, features that render this compound interesting for barocaloric applications. As for the obtained Raman spectra, they revealed that molecular vibrations associated to the NC₄, N₃⁻ and CH₃ molecular groups exhibit clear anomalies during the phase transitions, which include splits and discontinuity in the phonon wavenumber and lifetime. Furthermore, variation of the TMA⁺ and N₃⁻ modes with temperature revealed that while some modes follow the conventional red shift upon heating, others exhibit an unconventional blue shift, a result which was related to the weakening of the intermolecular interactions between the TMA (tetramethylammonium) cations and the azide ligands and the concomitant strengthening of the intramolecular bondings. Therefore, these studies show that Raman spectroscopy is a powerful tool to gain information about phase transitions, structures and intermolecular interactions between the A-cation and the framework, even in complex hybrid organic-inorganic perovskites with highly disordered phases.Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil); 431943/2016-8Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (Brasil); COOPI-07771/17Ministerio de Economía y Competitividad; MAT2017-86453-RXunta de Galicia; ED431G/0
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