971 research outputs found
Fast Gr\"obner Basis Computation for Boolean Polynomials
We introduce the Macaulay2 package BooleanGB, which computes a Gr\"obner
basis for Boolean polynomials using a binary representation rather than
symbolic. We compare the runtime of several Boolean models from systems in
biology and give an application to Sudoku
Inferring Biologically Relevant Models: Nested Canalyzing Functions
Inferring dynamic biochemical networks is one of the main challenges in
systems biology. Given experimental data, the objective is to identify the
rules of interaction among the different entities of the network. However, the
number of possible models fitting the available data is huge and identifying a
biologically relevant model is of great interest. Nested canalyzing functions,
where variables in a given order dominate the function, have recently been
proposed as a framework for modeling gene regulatory networks. Previously we
described this class of functions as an algebraic toric variety. In this paper,
we present an algorithm that identifies all nested canalyzing models that fit
the given data. We demonstrate our methods using a well-known Boolean model of
the cell cycle in budding yeast
Statistical support for the ATL program
Statistical experimental designs are presented for various numbers of organisms and agar solutions pertinent to the experiment, ""colony growth in zero gravity''. Missions lasting 7 and 30 days are considered. For the designs listed, the statistical analysis of the observations obtained on the space shuttle are outlined
The Evangelical Movement in Austria from 1945 to the Present: A Critical Appraisal
This essay examines the development of the Evangelical Movement in Austria from 1945 to the present. The history of the Evangelical Movement can be divided into four phases: The beginnings (1945-1961), which can be characterized above all by missionary work among ethnic German refugees of the World War II, a second phase from 1961-1981, which can be described as an internationalization of the Evangelical Movement especially through the work of North American missionaries. During this time new ways of evangelism were sought and also church planting projects were started. A third phase is characterized by a growing confessionalization and institutionalization of the Evangelical Movement. While free church congregation were increasingly taking on denominational contours, the evangelical movement as a whole began to increasingly establish its own institutions. The last phase since 1998 is characterized by the Evangelical Movement breaking out of isolation towards social and political acceptance
Compact and efficient sub-10 ps pump sources at 2 µm for the generation of coherent mid-infrared radiation
Ultrashort pulse laser systems in the 2 µm wavelength region featuring high pulse energies are powerful tools for driving a multitude of different applications in industry, medicine, and fundamental science. The implementation of such laser sources remains challenging and usually relies on the chirped-pulse amplification (CPA) in regenerative amplifiers. Here, a much more simplified concept based on a CPA-free multipass amplification scheme operating at room temperature has been investigated. I show that optical pulses with moderate sub-10 ps duration can be amplified up to the millijoule energy level without the onset of nonlinear effects in holmium-doped crystals. The laser system consists of an ultrafast all-fiber mode-locked oscillator and power amplifier based on holmium-doped silica fiber. It has been spectrally tailored to efficiently seed subsequent amplifiers based on holmium-doped YLiF4 crystals. A multipass amplification concept was used to amplify the nJ-level seed pulses from the fiber front-end up to 100 µJ of pulse energy at a pulse repetition frequency of 50 kHz. The maximum pulse energy was limited only by the laser-induced damage threshold of the amplifier crystals. Further pulse energy scaling has been achieved in a final single-pass booster amplifier generating 1.2 mJ at 1 kHz. The overall gain in the Ho:YLF crystals amounts to > 51 dB. Taking into account a measured pulse duration of 8.3 ps, this yields a pulse peak power of 136 MW. These results have been supported by numerical simulations based on a modified Frantz-Nodvik formalism, which is capable of modeling chromatic effects as well as a detailed description of the energy built-up in such amplifiers. Up to 50 µJ at 100 kHz from the multipass amplifier have been used to pump an optical parametric generator/amplifier tandem configuration based on the highly nonlinear non-oxide crystal ZnGeP2. The phase-matching condition has been set to achieve a signal and idler center wavelength of 3 µm and 6.5 µm, respectively. The maximum signal and idler pulse energy was 7.7 µJ and 2.5 µJ. Considering a measured pulse duration of 4 ps for both wavelengths, a peak intensity of about 2 MW (signal) and 0.5 MW (idler) was reached. The mid-IR coherent source is wavelength tunable covering the spectral range from 2.5 to 8 µm under appropriate phase-matching conditions and has shown long-term stability of less than 1.25%rms low-frequency power noise
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