Generation of internal stress and its effects

Internal stresses may be generated continually in many polycrystalline materials. Their existence is manifested by changes in crystal defect concentration and arrangement, by surface observations, by macroscopic shape changes and particularly by alteration of mechanical properties when external stresses are simultaneously imposed

Propfan Test Assessment (PTA): Flight test report

The Propfan Test Assessment (PTA) aircraft was flown to obtain glade stress and noise data for a 2.74m (9 ft.) diameter single rotation propfan. Tests were performed at Mach numbers to 0.85 and altitudes to 12,192m (40,000 ft.). The propfan was well-behaved structurally over the entire flight envelope, demonstrating that the blade design technology was completely adequate. Noise data were characterized by strong signals at blade passage frequency and up to 10 harmonics. Cabin noise was not so high as to preclude attainment of comfortable levels with suitable wall treatment. Community noise was not excessive

pyCM: An open-source computational framework for residual stress analysis employing the Contour Method

The contour method for assessing residual stress is a widely accessible method in terms of the equipment required and experimental protocol. However, its application is hampered by the absence of a common computational framework to reconstruct the residual stress field and visualise the final result. In order to help regularise the analysis an open-source reconstruction package is presented: the Python Contour Method (pyCM). This package comprises a graphical user interface framework for the purposes for analysing and resolving stresses from experimental contour method data. The code requires no proprietary software and is expandable and fully transparent, enabling users to evaluate it and extend it to develop best practice. The framework is presented and compared against results stemming from a widely published edge-welded beam dataset produced as part of the EC 5th Framework ENPOWER project to highlight applicability

The Female Athlete Triad in Adolescent Athletes

The number of teenage girls participating in sports has dramatically increased in the last few decades (Brown et al., 2017). With increased sports participation, the positive effects of physical activity have become obvious (Thein-Nissenbaum & Hammer, 2017). However, a set of health-related problems specific to female athletes, known as the female athlete triad (triad), has emerged. This fact sheet will cover what the triad is, why the triad occurs, and triad prevention and treatment

Late time solutions for inhomogeneous Lambda-CDM cosmology, their characterization and observation

Assuming homogeneous isotropic Lambda-CDM cosmology allows Lambda, spatial curvature and dark matter density to be inferred from large scale structure observations such as supernovae. The purpose of this paper is to extend this to allow observations to measure or constrain inhomogeneity and anisotropy. We obtain the general inhomogeneous anisotropic Lambda-CDM solution which is locally asymptotic to an expanding de Sitter solution as a late time expansion using Starobinsky's method (analogous to the `holographic renormalization' technique in AdS/CFT) together with a resummation of the series. The dark matter is modeled as perfect dust fluid. The terms in the expansion systematically describe inhomogeneous and anisotropic deformations of an expanding FLRW solution, and are given as a spatial derivative expansion in terms of data characterizing the solution - a 3-metric and a perturbation of that 3-metric. Leading terms describe inhomogeneity and anisotropy on the scale set by the cosmological constant, approximately the horizon scale today. Higher terms in the expansion describe shorter scale variations. We compute the luminosity distance-redshift relation and argue that comparison with current and future observation would allow a partial reconstruction of the characterizing data. We also comment on smoothing these solutions noting that geometric flows (such as Ricci flow) applied to the characterizing data provide a canonical averaging method.Comment: 15 pages, 2 figures; v2: minor corrections and improvements, references adde

Anisotropic magnetoconductance and Coulomb blockade in defect engineered Cr2Ge2Te6 van der Waals heterostructures

This is the final version. Available from the American Physical Society via the DOI in this record.We demonstrate anisotropic tunnel magnetoconductance by controllably engineering charging islands inthe layered semiconducting ferromagnet Cr2Ge2Te6. This is achieved by assembling vertical van der Waalsheterostructures comprised of graphene electrodes separated by crystals of Cr2Ge2Te6. Carefully applyingvertical electric fields in the region of (E∼25–50 mV/nm) across the Cr2Ge2Te6causes its dielectric breakdownat cryogenic temperatures. This breakdown process has the effect of introducing subgap defect states withinthe otherwise semiconducting ferromagnetic material. Low-temperature electron transport through chargingislands reveals Coulomb blockade behavior with a strongly gate-tuneable anisotropic magnetoconductance,which persists up toT∼60 K. We report average tunnel magnetoresistance values of 100%. This work opensnew avenues and material systems for the development of nanometer-scale electrically controlled spintronicdevices.Royal Academy of Engineering (RAE)Royal SocietyEngineering and Physical Sciences Research Council (EPSRC

Rate-controlling processes during environment-sensitive crack propagation in aluminum

Recent experimental findings are challenging today’s conventional view on the rate-controlling processes during environment-sensitive crack growth in aluminum alloys when exposed to moist air and aqueous environments. X-ray computed tomography has revealed the detailed crack morphology of several stress corrosion cracks in 7000 series alloys and this has shown that the complexity of the mesoscale is incredibly important to understand the links between the gross morphology of the crack and the crack front/tip. We will show the large local variation that exists in the crack morphology. At the same time we will show how average measurements of crack velocity and crack opening displacement remain surprisingly uniform across the width of the crack. Discussion will follow in an effort to quantify the effect of Keffective compared to Kapplied and to provide a rationalization of these findings with respect to previously published theories

β-synuclein potentiates synaptic vesicle dopamine uptake and rescues dopaminergic neurons from MPTP-induced death in the absence of other synucleins.

Synucleins, a family of three proteins highly expressed in neurons, are predominantly known for the direct involvement of α-synuclein in the aetiology and pathogenesis of Parkinson's and certain other neurodegenerative diseases, but their precise physiological functions are still not fully understood. Previous studies have demonstrated the importance of α-synuclein as a modulator of various mechanisms implicated in chemical neurotransmission, but information concerning the involvement of other synuclein family members, β-synuclein and γ-synuclein, in molecular processes within presynaptic terminals is limited. Here we demonstrated that the vesicular monoamine transporter 2 (VMAT2)-dependent dopamine uptake by synaptic vesicles isolated from the striatum of mice lacking β-synuclein is significantly reduced. Reciprocally, reintroduction, either in vivo or in vitro, of β-synuclein but not α- or γ-synuclein improves uptake by triple α/β/γ-synuclein deficient striatal vesicles. We also showed that the resistance of dopaminergic neurons of the substantia nigra pars compacta (SNpc) to subchronic administration of the Parkinson's disease-inducing prodrug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) depends on the presence of β-synuclein but only when one or both other synucleins are absent. Furthermore, proteomic analysis of synuclein-deficient synaptic vesicles vs those containing only β-synuclein revealed differences in their protein compositions. We suggest that the observed potentiation of dopamine uptake by β-synuclein might be caused by different protein architecture of the synaptic vesicles. It is also feasible that such structural changes improve synaptic vesicle sequestration of 1-methyl-4-phenylpyridinium (MPP+), a toxic metabolite of MPTP, which would explain why dopaminergic neurons expressing β-synuclein and lacking α-synuclein and/or γ-synuclein are resistant to this neurotoxin

Competition of stress corrosion crack branches observed in-situ using time-lapse 3D x-ray synchrotron computed tomography

The progress of a stress corrosion crack in a sensitized AA7075 alloy was studied by in-situ x-ray synchrotron computed tomography. A load was applied to a pre-cracked specimen inside an environmental cell containing moist air and the propagation of the stress corrosion crack was observed. Measurements from the 3D image of the crack have already been shown to provide better quantification compared to observations of the crack from the outer surface. In this paper we study in detail the progress of the stress corrosion crack as it propagates through the material. We reveal how the formation of metal ligaments occurs and the competition of the ‘main’ crack and its branches. We have visualized these features to show the complexity of the local variation in crack morphology in a way that brings new insight into the interaction of the stress corrosion crack with the microstructure of the material