Debonding analysis via digital volume correlation during in-situ pull-out tests on fractal fibers

The quantification of debonding was performed for additively manufactured “fractal” fibers embedded within two brittle matrices. Three pull-out tests were carried out inside of an X-ray tomograph allowing for Digital Volume Correlation analyses. Relative motions at the interfaces were measured thanks to adapted meshes with split nodes. Profiles of normal, tangential and vertical displacement jumps as well as vertical strains in the fibers were used to study interfacial debonding. An articulated load transfer mechanism between the fiber and the matrix was observed in the examined tests, as demonstrated by zigzagged distributions of vertical displacement jumps and vertical strain profiles in the fibers at the initial stages of pull-out. Vertical strain concentrations were observed in correspondence to lateral protrusions (or ribs) of the reinforcing fibers. These results suggest that fiber–matrix interlocking may be affected by geometry-driven tensile stiffening effects between the ribs. For larger values of pull-out displacements, more diffuse damage of the fiber–matrix interface was observed between the ribs, especially in plaster matrices

Universal homodyne tomography with a single local oscillator

We propose a general method for measuring an arbitrary observable of a multimode electromagnetic field using homodyne detection with a single local oscillator. In this method the local oscillator scans over all possible linear combinations of the modes. The case of two modes is analyzed in detail and the feasibility of the measurement is studied on the basis of Monte-Carlo simulations. We also provide an application of this method in tomographic testing of the GHZ state.Comment: 12 pages, 5 figures (8 eps files

SEQUIN: a grammar inference framework for analyzing malicious system behavior

Open access articleTargeted attacks on IT systems are a rising threat to the confidentiality of sensitive data and the availability of critical systems. The emergence of Advanced Persistent Threats (APTs) made it paramount to fully understand the particulars of such attacks in order to improve or devise effective defense mechanisms. Grammar inference paired with visual analytics (VA) techniques offers a powerful foundation for the automated extraction of behavioral patterns from sequential event traces. To facilitate the interpretation and analysis of APTs, we present SEQUIN, a grammar inference system based on the Sequitur compression algorithm that constructs a context-free grammar (CFG) from string-based input data. In addition to recursive rule extraction, we expanded the procedure through automated assessment routines capable of dealing with multiple input sources and types. This automated assessment enables the accurate identification of interesting frequent or anomalous patterns in sequential corpora of arbitrary quantity and origin. On the formal side, we extended the CFG with attributes that help describe the extracted (malicious) actions. Discovery-focused pattern visualization of the output is provided by our dedicated KAMAS VA prototype

Sexual selection predicts species richness across the animal kingdom

Funding: Swiss National Science Foundation to T. J. (PA00P3-145375/1) and to L.M.-O. (P2BSP3_158842 and P300PA_171516).Our improving knowledge of the animal tree of life consistently demonstrates that some taxa diversify more rapidly than others, but what contributes to this variation remains poorly understood. An influential hypothesis proposes that selection arising from competition for mating partners plays a key role in promoting speciation. However, empirical evidence showing a link between proxies of this sexual selection and species richness is equivocal. Here, we collected standardized metrics of sexual selection for a broad range of animal taxa, and found that taxonomic families characterized by stronger sexual selection on males show relatively higher species richness. Thus, our data support the hypothesis that sexual selection elevates species richness. This could occur either by promoting speciation and/or by protecting species against extinction.PostprintPeer reviewe

Talbot Oscillations and Periodic Focusing in a One-Dimensional Condensate

An exact theory for the density of a one-dimensional Bose-Einstein condensate with hard core particle interactions is developed in second quantization and applied to the scattering of the condensate by a spatially periodic impulse potential. The boson problem is mapped onto a system of free fermions obeying the Pauli exclusion principle to facilitate the calculation. The density exhibits a spatial focusing of the probability density as well as a periodic self-imaging in time, or Talbot effect. Furthermore, the transition from single particle to many body effects can be measured by observing the decay of the modulated condensate density pattern in time. The connection of these results to classical and atom optical phase gratings is made explicit

Least-squares inversion for density-matrix reconstruction

We propose a method for reconstruction of the density matrix from measurable time-dependent (probability) distributions of physical quantities. The applicability of the method based on least-squares inversion is - compared with other methods - very universal. It can be used to reconstruct quantum states of various systems, such as harmonic and and anharmonic oscillators including molecular vibrations in vibronic transitions and damped motion. It also enables one to take into account various specific features of experiments, such as limited sets of data and data smearing owing to limited resolution. To illustrate the method, we consider a Morse oscillator and give a comparison with other state-reconstruction methods suggested recently.Comment: 16 pages, REVTeX, 6 PS figures include

Self-homodyne tomography of a twin-beam state

A self-homodyne detection scheme is proposed to perform two-mode tomography on a twin-beam state at the output of a nondegenerate optical parametric amplifier. This scheme has been devised to improve the matching between the local oscillator and the signal modes, which is the main limitation to the overall quantum efficiency in conventional homodyning. The feasibility of the measurement is analyzed on the basis of Monte-Carlo simulations, studying the effect of non-unit quantum efficiency on detection of the correlation and the total photon-number oscillations of the twin-beam state.Comment: 13 pages (two-column ReVTeX) including 21 postscript figures; to appear on Phys. Rev.

Evaluation of nutrition care to adult patients on HAART attending primary healthcare facilities in Mpumalanga

CITATION: Schiever, J. F. et al. 2019. Evaluation of nutrition care to adult patients on HAART attending primary healthcare facilities in Mpumalanga, South African Journal of Clinical Nutrition, 32(1):13-20. doi:10.1080/16070658.2017.1412183The original publication is available at https://www.tandfonline.com/toc/ojcn20/currentObjectives: This study aimed to evaluate nutrition care and nursing professional knowledge received by adults on highly active antiretroviral therapy attending primary health care (PHC) facilities Design: Cross-sectional, descriptive study. Subjects and setting: The study was conducted on 263 adults and 75 nursing professionals, recruited from 19 facilities in the Mbombela sub-district, Mpumalanga. Outcome measures: Interviewer-administered questionnaires were completed for each patient. Nursing professionals completed a self-administered questionnaire. Assessment tools were completed for each facility. Results: Some 41% of patients were either overweight or obese, and most females (n = 87; 51.8%) had a BMI ≥ 25 kg/m2. Based on waist circumference, 52.7% (n = 88) of females and 8.4% (n = 8) of males showed increased risk of cardiovascular disease. Although nurses were aware of a nutrition supplementation programme, knowledge of national nutrition guidelines was inadequate. Clinical judgement, rather than eligibility criteria, was used to identify suitable patients, with 13.3% (n = 35) receiving supplementation whereas only 4.9% (n = 13) qualified. Facilities generally had sufficient equipment and fair storage conditions, but stock shortages of nutrition supplements were problematic. Conclusions: Whilst certain positive findings emerged, nutrition care could be improved, largely through adequate training and support to professional nurses. Training should focus on correct execution of assessment measurements and appropriate nutritional counselling, emphasising balanced eating, food security and prevention of over-nutrition. Nurses should be familiarised with national nutrition guidelines and have access to a constant nutrition supplementation supply. Improved monitoring and evaluation of nutrition care to adults on treatment at PHC facilities is needed.https://www.tandfonline.com/doi/full/10.1080/16070658.2017.1412183Publisher’s versio

High resolution amplitude and phase gratings in atom optics

An atom-field geometry is chosen in which an atomic beam traverses a field interaction zone consisting of three fields, one having frequency $\Omega =c/\lambda$ propagating in the $\hat{z}$ direction and the other two having frequencies $\Omega +\delta_{1}$ and $\Omega +\delta_{2}$ propagating in the -$\hat{z}$ direction. For $n_{1}\delta_{1}+n_{2}\delta_{2}=0$ and $|\delta_{1}| T,|\delta_{2}| T\gg 1$, where $n_{1}$ and $n_{2}$ are positive integers and $T$ is the pulse duration in the atomic rest frame, the atom-field interaction results in the creation of atom amplitude and phase gratings having period $\lambda /[2(n_{1}+n_{2})]$. In this manner, one can use optical fields having wavelength $\lambda$ to produce atom gratings having periodicity much less than $\lambda$.Comment: 11 pages, 14 figure

Phase dynamics in a binary-collisions atom laser scheme

Various aspects of the phase dynamics of an atom laser scheme based on binary collisions are investigated. Analytical estimates of the influence of elastic atom-atom collisions on the laser linewidth are given, and linewidths achievable in a recently proposed atom laser scheme [Phys. Rev. A 56, 2989 (1997)] are evaluated explicitly. The extent to which a relative phase can be established between two interfering atom lasers, as well as the properties of that phase, are also investigated.Comment: Revtex, 10 pages, 6 figure