Strain field analysis of cancellous bone under compression by image correlation

Experimental mechanical analysis of cancellous bone has been performed to capture the global strain field of specimens under compression. One major objective is to assess the test procedure and obtain the cancellous bone mechanical properties. Now a day, several techniques are available for the experimental measurement of the field displacement. Among them, the Cross-Correlation is one of most simple’s techniques and can be applied to several studies cases. Based on the correlation of random speckle pattern between two images, the spatial displacement fields can be accessed. A simple digital camera or video recorder can be used without special light to capture the surface intensity pattern in each instant. If several images are taken during a test loading, the displacement field can be fallowed and subsequently the strain can be obtain by the spatial differentiation. Because of random surface pattern, the image can be divided in small areas, each of them pattern independent. By cross-correlating each of one between the two images, the relative displacement is obtained

Multispecies virial expansions

We study the virial expansion of mixtures of countably many different types of particles. The main tool is the Lagrange–Good inversion formula, which has other applications such as counting coloured trees or studying probability generating functions in multi-type branching processes. We prove that the virial expansion converges absolutely in a domain of small densities. In addition, we establish that the virial coefficients can be expressed in terms of two-connected graphs

Normal-state conductivity in underdoped La_{2-x}Sr_xCuO_4 thin films: Search for nonlinear effects related to collective stripe motion

We report a detailed study of the electric-field dependence of the normal-state conductivity in La_{2-x}Sr_xCuO_4 thin films for two concentrations of doped holes, x=0.01 and 0.06, where formation of diagonal and vertical charged stripes was recently suggested. In order to elucidate whether high electric fields are capable of depinning the charged stripes and inducing their collective motion, we have measured current-voltage characteristics for various orientations of the electric field with respect to the crystallographic axes. However, even for the highest possible fields (~1000 V/cm for x=0.01 and \~300 V/cm for x=0.06) we observed no non-linear-conductivity features except for those related to the conventional Joule heating of the films. Our analysis indicates that Joule heating, rather than collective electron motion, may also be responsible for the non-linear conductivity observed in some other 2D transition-metal oxides as well. We discuss that a possible reason why moderate electric fields fail to induce a collective stripe motion in layered oxides is that fairly flexible and compressible charged stripes can adjust themselves to the crystal lattice and individual impurities, which makes their pinning much stronger than in the case of conventional rigid charge-density waves.Comment: 10 pages, 10 figures, accepted for publication in Phys. Rev.

Topology Control in Cooperative Ad Hoc Wireless Networks

AbstractCooperative communication (CC) is a technique that exploits spatial diversity allowing multiple nodes to cooperatively relay signals to the receiver so that it can combine the received signals to obtain the original message. CC can be combined with topology control to increase connectivity at the cost of a small increase in energy consumption. This work focuses on exploring CC to improve the connectivity with a sink node in ad hoc wireless networks. More precisely, this work proposes a new technique, named CoopSink, that combines CC and topology control techniques to increase connectivity to a sink node while ensuring energy-efficient routes. Simulation results show that connectivity and routing to the sink cost can be improved up to 6.8 and 2.3 times, respectively, when compared with other similar strategies

Diagnostic and therapeutic approach to cardioinhibitory reflex syncopeA complex and controversial issue

Syncope is defined as a transient loss of consciousness due to global cerebral hypoperfusion and is one of the leading causes of emergency department admission. The initial approach should focus on excluding non‐syncopal causes for loss of consciousness and risk stratification for cardiac cause, in order to ensure an appropriate etiological investigation and therapeutic approach. Vasovagal syncope (VVS), the most common type of syncope, should be assumed once other causes are excluded. Pathophysiologically, the vasovagal reflex is the result of a paradoxical autonomic response, leading to hypotension and/or bradycardia. VVS has not been shown to affect mortality, but morbidity may be considerable in those with recurrent syncopal episodes. The management of VVS includes both non‐pharmacological and pharmacological measures that act on various levels of the reflex arc that triggers the syncopal episode. However, most are of uncertain benefit given the scarcity of high‐quality supporting evidence. Pacemaker therapy may be considered in recurrent refractory cardioinhibitory reflex syncope, for which it is currently considered a robust intervention, as noted in the European guidelines. Non‐randomized and unblinded studies have shown a potential benefit of pacing in recurrent VVS, but double‐blinded randomized controlled trials have not consistently demonstrated positive results. We performed a comprehensive review of the current literature and recent advances in cardiac pacing and pacing algorithms in VVS, and discuss the diagnostic and therapeutic approach to the complex patient with recurrent VVS and reduced quality of life.publishersversionpublishe

Theranostic nanoparticles enhance the response of glioblastomas to radiation

YesDespite considerable progress with our understanding of glioblastoma multiforme (GBM) and the precise delivery of radiotherapy, the prognosis for GBM patients is still unfavorable with tumor recurrence due to radioresistance being a major concern. We recently developed a cross-linked iron oxide nanoparticle conjugated to azademethylcolchicine (CLIO-ICT) to target and eradicate a subpopulation of quiescent cells, glioblastoma initiating cells (GICs), which could be a reason for radioresistance and tumor relapse. The purpose of our study was to investigate if CLIO-ICT has an additive therapeutic effect to enhance the response of GBMs to ionizing radiation. Methods: NSG™ mice bearing human GBMs and C57BL/6J mice bearing murine GBMs received CLIO-ICT, radiation, or combination treatment. The mice underwent pre- and post-treatment magnetic resonance imaging (MRI) scans, bioluminescence imaging (BLI), and histological analysis. Tumor nanoparticle enhancement, tumor flux, microvessel density, GIC, and apoptosis markers were compared between different groups using a one-way ANOVA and two-tailed Mann-Whitney test. Additional NSG™ mice underwent survival analyses with Kaplan–Meier curves and a log rank (Mantel–Cox) test. Results: At 2 weeks post-treatment, BLI and MRI scans revealed significant reduction in tumor size for CLIO-ICT plus radiation treated tumors compared to monotherapy or vehicle-treated tumors. Combining CLIO-ICT with radiation therapy significantly decreased microvessel density, decreased GICs, increased caspase-3 expression, and prolonged the survival of GBM-bearing mice. CLIO-ICT delivery to GBM could be monitored with MRI. and was not significantly different before and after radiation. There was no significant caspase-3 expression in normal brain at therapeutic doses of CLIO-ICT administered. Conclusion: Our data shows additive anti-tumor effects of CLIO-ICT nanoparticles in combination with radiotherapy. The combination therapy proposed here could potentially be a clinically translatable strategy for treating GBMs

Avanços recentes em nutrição de larvas de peixes

Os requisitos nutricionais de larvas de peixes são ainda mal compreendidos, o que leva a altas mortalidades e problemas de qualidade no seu cultivo. Este trabalho pretende fazer uma revisão de novas metodologias de investigação, tais como estudos com marcadores, genómica populacional, programação nutricional, génomica e proteómica funcionais, e fornecer ainda alguns exemplos das utilizações presentes e perspectivas futuras em estudos de nutrição de larvas de peixes