Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Shakeup excitation during optical tunnel ionization Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1103/PhysRevLett.94.033003Physical Review Letters, 94, 3, 2005-01- Shakeup of a two-electron system is investigated in the strong infrared laser field limit, both theoretically and experimentally. During tunnel ionization the electron shakes up a second electron to an excited bound state. Theoretically, a complete analytical theory of shakeup in intense laser fields is developed. We predict that shakeup produces one excited u D 2 state in 10 5 ionization events. Shakeup is measured experimentally by using the molecular clock provided by the internuclear motion. The number of measured events is found to be in excellent agreement with theory.

Steganography is used to embed secret messages in cover media. This is especially important in areas, where the use of cryptography is prohibited. In this paper, we introduce a novel hybrid steganographic algorithm for digital audio data. We enhance a direct sequence spread spectrum (DSSS) system with aspects of frequency hopping to vary the carrier frequency of the binary phase shift keying (BPSK) signal, representing the secret message. Further, we adopt the number of chips per secret bit. These modifications give a more secure steganographic system, making guesses about the bit-rate or message length less feasible. Further, an adaptive amplitude control is used to guarantee inaudibility, even in silent passages. After an overview of the DSSS technique, we highlight our contributions to form a more secure steganographic system. The results from our working prototype are pointed out and further usage scenarios in relation to future research are given.

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A simplified design for an on demand routing protocol using pheromone (attractiveness) gradients for data forwarding decisions is proposed. The developed Pheromonebased Routing Strategy (PRS) provides an easy concept for a data-centric routing protocol in wireless sensor networks. The protocol has a flat hierarchy, works on-demand, is sourceinitiated and has its origin in the idea of ant-based routing. During development of PRS, the important variable pheromone was turned into a special factor for link costs and is the sole determinant for data load propagation where the pheromone level of the sensor node defines its attractiveness for forwarding data. The link costs called pheromone are calculated from the sensor nodes' energy status, as well as the received signal strength and the current buffer (sensor on board memory) fill level. PRS only supports node-to-sink data traffic and therefore is a lightweight approach to generalized multihop routing algorithms in WSNs. The PRS routing protocol is implemented on a MSP430F149 low power microcontroller using a CC2420 wireless interface which are acting together as a sensor node. For performance evaluation of PRS a multi-agent based simulation environment called NetLogo is used.