Exploring the temporally resolved electron density evolution in EUV induced plasmas

We measured for the first time the electron density in an Extreme Ultra-Violet induced plasma. This is achieved in a low-pressure argon plasma by using a method called microwave cavity resonance spectroscopy. The measured electron density just after the EUV pulse is $2.6\cdot10^{16}$ m$^{-3}$. This is in good agreement with a theoretical prediction from photo ionization, which yields a density of $4.5\cdot10^{16}$ m$^{-3}$. After the EUV pulse the density slightly increase due to electron impact ionization. The plasma (i.e. electron density) decays in tens of microseconds.Comment: 3 pages, 4 figure

Side-channel based intrusion detection for industrial control systems

Industrial Control Systems are under increased scrutiny. Their security is historically sub-par, and although measures are being taken by the manufacturers to remedy this, the large installed base of legacy systems cannot easily be updated with state-of-the-art security measures. We propose a system that uses electromagnetic side-channel measurements to detect behavioural changes of the software running on industrial control systems. To demonstrate the feasibility of this method, we show it is possible to profile and distinguish between even small changes in programs on Siemens S7-317 PLCs, using methods from cryptographic side-channel analysis.Comment: 12 pages, 7 figures. For associated code, see https://polvanaubel.com/research/em-ics/code

Spectropolarimetric observations of Herbig Ae/Be Stars I: HiVIS spectropolarimetric calibration and reduction techniques

Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS telescope in Hawaii, we are collecting a large number of high precision spectropolarimetrc observations of stars. In order to precisely measure very small polarization changes, we have performed a number of polarization calibration techniques on the AEOS telescope and HiVIS spectrograph. We have extended our dedicated IDL reduction package and have performed some hardware upgrades to the instrument. We have also used the ESPaDOnS spectropolarimeter on CFHT to verify the HiVIS results with back-to-back observations of MWC 361 and HD163296. Comparision of this and other HiVIS data with stellar observations from the ISIS and WW spectropolarimeters in the literature further shows the usefulness of this instrument.Comment: 35 pages, 44 figures, Accepted by PAS

Invariant vector fields and the prolongation method for supersymmetric quantum systems

The kinematical and dynamical symmetries of equations describing the time evolution of quantum systems like the supersymmetric harmonic oscillator in one space dimension and the interaction of a non-relativistic spin one-half particle in a constant magnetic field are reviewed from the point of view of the vector field prolongation method. Generators of supersymmetries are then introduced so that we get Lie superalgebras of symmetries and supersymmetries. This approach does not require the introduction of Grassmann valued differential equations but a specific matrix realization and the concept of dynamical symmetry. The Jaynes-Cummings model and supersymmetric generalizations are then studied. We show how it is closely related to the preceding models. Lie algebras of symmetries and supersymmetries are also obtained.Comment: 37 pages, 7 table

Energy-Filtering Transmission Electron Microscopy of Biological Specimens

By energy-filtering transmission electron microscopy (EFTEM) electrons can be separated by their energy losses. An electron-energy filter, added to the microscope column allows the measurement of the energy distribution of transmitted electrons that have lost energy (\u3c 2,000 eV, with an energy resolution of ~ 1 eV). These filtered electrons, recorded either as a spectrum or as an image, are composed of two parts superimposed on top of each other: (a) the unspecific energy-loss population (= the continuum) and (b) the specific element-related energy-loss population (= the edges). At the edges, electron data in spectra and images are mathematically processed, to obtain the desired element-related net-intensity values or images. These data are related to the total transmitted electron intensity, from the zero-and low-loss spectral region giving the relative spectral-or image intensity ratios (SR*x, IR*x), which can be related to the element concentration. The acquisition of the zero-loss and low-loss data is hampered by the restricted dynamic range of the TV camera. By improvements through the introduction of calibrated attenuation filters in the optical path to the TV-camera, more reliable values for SR*x and IR*x can be acquired. By addition of Bio-standards adjacent to the tissue, a known and unknown concentration of the element present in the same ultrathin section and the bias in the concentration estimation, can be obtained. Some practical examples are given for the estimation of the iron concentration in siderosomes, boron in melanosomes and calcium in calcium oxalate monohydrate crystals

Étude de l’oestrus et de la fertilité après un traitement de maîtrise des cycles chez les femelles zébus

La recherche a visé à établir les taux de réponse et conception des animaux synchronisés au Crestar® associé à la PMSG. 39 femelles zébus (Bos indicus) Goudali et Azawak constitué de vaches et de génisses ont été utilisées dans l’étude. L’insémination artificielle a été faite de façon systématique 48 heures après l’arrêt du traitement. Le diagnostic de gestation a été déterminé 60 jours après insémination par palpation rectale. Le taux global de l’oestrus induit a été de 94,87%. La parité et la race de femelles n’ont eu aucun effet significatif sur la réponse de l’oestrus. Le délai d’apparition de l’oestrus a été de 30,11 ± 6,24 heures et 32,76 ± 4,75 heures après la fin du traitement respectivement pour les femelles zébus Goudali et Azawak. La durée moyenne de l’oestrus a été de 12,20 ± 1,30 heures (n = 5). Le taux global de fertilité a été de 41,03%. La parité et la race de femelles n’ont eu aucun effet significatif sur la fertilité.Mots clés: Insémination artificielle, Crestar, taux de gestation, synchronisation, Nige

Hypergravity influence on gliding arc in noble gases

The effects of increased artificial gravity (in the range 1g-18g) on gliding arcs in four noble gases (He, Ne, Ar, Kr) were the subject of this experimental study