Compression after multiple low velocity impacts of NCF, 2D and 3D woven composites

This paper investigates the effect of the fabric architecture and the z-binding yarns on the compression after multiple impacts behavior of composites. Four fiber architectures are investigated: non-crimp fabric (NCF), 2D plain weave (2D-PW), 3D orthogonal plain (ORT-PW) and twill (ORT-TW) weave. The specimens were subjected to single and multiple low-velocity impacts at different locations with the same energy level (15 J). Non-destructive techniques including ultrasonic C-scanning, X-ray CT and Digital Image Correlation (DIC) are employed to quantitatively analyze and capture the Barely Visible Impact Damage (BVID) induced in the specimens. Although the absorbed energy was approximately the same, damage was the least in 3D woven architectures. In the case of compression after impact, 3D woven composites demonstrated a progressive damage behavior with the highest residual strength (~92%) while 2D plain weave and NCF specimens showed suddenly catastrophic damage and the residual strength of ~65% and ~55% respectively

A Spectral Bernstein Theorem

We study the spectrum of the Laplace operator of a complete minimal properly immersed hypersurface $M$ in $\R^{n+1}$. (1) Under a volume growth condition on extrinsic balls and a condition on the unit normal at infinity, we prove that $M$ has only essential spectrum consisting of the half line $[0, +\infty)$. This is the case when $\lim_{\tilde{r}\to +\infty}\tilde{r}\kappa_i=0$, where $\tilde{r}$ is the extrinsic distance to a point of $M$ and $\kappa_i$ are the principal curvatures. (2) If the $\kappa_i$ satisfy the decay conditions $|\kappa_i|\leq 1/\tilde{r}$, and strict inequality is achieved at some point $y\in M$, then there are no eigenvalues. We apply these results to minimal graphic and multigraphic hypersurfaces.Comment: 16 pages. v2. Final version: minor revisions, we add Proposition 3.2. Accepted for publication in the Annali di Matematica Pura ed Applicata, on the 05/03/201

Electron Electric Dipole Moment from Lepton Flavor Violation

The general Minimal Supersymmetric Standard Model introduces new sources for Lepton Flavor Violation (LFV) as well as CP-violation. In this paper, we show that when both sources are present, the electric dipole moment of the electron, $d_e$, receives a contribution from the phase of the trilinear $A$-term of staus, $\phi_{A_\tau}$. For $\phi_{A_\tau}=\pi/2$, the value of $d_e$, depending on the ratios of the LFV mass elements, can range between zero and three orders of magnitude above the present bound. We show that the present bound on $d_e$ rules out a large portion of the CP-violating and the LFV parameter space which is consistent with the bounds on the LFV rare decays. We show that studying the correlation between $d_e$ and the P-odd asymmetry in $\tau \to e\gamma$ helps us to derive a more conclusive bound on $\phi_{A_\tau}$ We also discuss the possibility of cancelation among the contributions of different CP-violating phases to $d_e$.Comment: 35 pages, 9 figure

Modelling the COVID-19 pandemic in context : An international participatory approach

Funding RA is funded by the Bill and Melinda Gates Foundation (OPP1193472). LW is funded by the Li Ka Shing Foundation. CF is funded by grant #2017/26770-8, São Paulo Research Foundation (FAPESP). The CoMo Consortium has support from the Oxford University COVID-19 Research Response Fund (ref: 0009280). Scientific writing assistance and editorial support was provided by Adam Bodley, according to Good Publication Practice guidelines.Peer reviewedPublisher PD

Taxonomy based on science is necessary for global conservation

Peer reviewe