3,319 research outputs found
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 m. This
is in good agreement with a theoretical prediction from photo ionization, which
yields a density of m. 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
Biodegradable, lignin-based encapsulation enables delivery of Trichoderma reesei with programmed enzymatic release against grapevine trunk diseases
Antagonistic fungi such as Trichoderma reesei are promising alternatives to conventional fungicides in agriculture. This is especially true for worldwide occurring grapevine trunk diseases, causing losses of US$1.5 billion every year, at which conventional fungicides are mostly ineffective or prohibited by law. Yet, applications of Trichoderma against grapevine trunk diseases are limited to preventive measures, suffer from poor shelf life, or uncontrolled germination. Therefore, we developed a mild and spore-compatible layer-by-layer assembly to encapsulate spores of a new mycoparasitic strain of T. reesei IBWF 034-05 in a bio-based and biodegradable lignin shell. The encapsulation inhibits undesired premature germination and enables the application as an aqueous dispersion via trunk injection. First injected into a plant, the spores remain in a resting state. Second, when lignin-degrading fungi infect the plant, enzymatic degradation of the shell occurs and germination is selectively triggered by the pathogenic fungi itself, which was proven in vitro. Germinated Trichoderma antagonizes the fungal pathogens and finally supplants them from the plant. This concept enables Trichoderma spores for curative treatment of esca, one of the most infective grapevine trunk diseases worldwide
A Statistical Analysis of the SOT-Hinode Observations of Solar Spicules and their Wave-like Behavior
We consider a first important parameter of spicules as observed above the
solar visible limb: their apparent diameter as a function of the height above
the limb which determines their aspect ratio and leads to the discussion of
their magnetic origin using the flux tube approximation. We found that indeed
spicules show a whole range of diameters, including unresolved "interacting
spicules" (I-S), depending of the definition chosen to characterize this
ubiquitous dynamical phenomenon occurring into a low coronal surrounding. 1-D
Fourier amplitude spectra (AS) made at different heights above the limb are
shown for the first time. A definite signature in the 0.18 to 0.25 Mm range
exists, corresponding to the occurrence of the newly discovered type II
spicules and, even more impressively, large Fourier amplitudes are observed in
the 0.3 to the 1.2 Mm range of diameters and spacing, in rough agreement with
what historical works were reporting. Additionally, some statistically
significant behavior, based on AS computed for different heights above the
limb, is discussed. "Time slice or x-t diagrams" revealing the dynamical
behavior of spicules are also analyzed. They show that most of spicules have
multiple structures (similarly to the doublet spicules) and they show
impressive transverse periodic fluctuations which were interpreted as upward
kink or Alfven waves. Evidence of the helical motion in spicules is now well
evidenced, the typical periods of the apparent oscillation being around 120
sec. A fine analysis of the time-slice diagram as a function of the effective
heights shows an interesting new feature near the 2 Mm height. We speculate on
the interpretation of this feature as being a result of the dynamical
specificities of the spicule helical motion as seen in these unprecedented high
resolution HCaII line emission time series.Comment: 21 pages, 8 figurs, 1 tabl
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
Towards the production of 50'000 tonnes of low-carbon steel sheet for the LHC superconducting dipole and quadrupole magnets
A total of 50'000 tonnes of low-carbon steel sheet has been ordered for the LHC main magnets. After three years of production, about 10'000 tonnes of steel sheet have been produced by Cockerill-Sambre Groupe Usinor. This paper gives a summary of the manufacturing process and improvements implemented as well as an overview of the difficulties encountered during this production. Preliminary statistics obtained for the mechanical and magnetic steel properties are presented
Plasma accumulation effects in Extreme Ultra-Violet generated plasmas
In order to meet the demand of increasing computer speed and memory capacity, industries are striving to reduce the size of computer chips. This miniaturization can be achieved by reducing the wavelength in lithography machines to Extreme Ultra-Violet (EUV, 92 eV). The low-pressure (around 1 Pa) transparent background gas (e.g. H2 and He) in the lithography machine is partially ionized by the absorption of EUV photons. The study of these low-density 1E15 m^-3 pulsed plasmas is interesting and experimentally challenging. The electron density is measured with microwave cavity resonance spectroscopy (MCRS). In MCRS measurements the resonance frequency in a cavity is determined, this frequency depends on the electron density in the cavity. In this research the plasma accumulation is studied in an EUV-generated plasma in argon. The EUV source generates EUV pulses with a repetition frequency between 500 Hz and 10 kHz. The accumulation of plasma is clearly observed at frequencies above 1 kHz
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