From an expert's standpoint, an Android phone is a large data repository that can be stored either locally or remotely. Besides, its platform allows analysts to acquire device data and evidence, collecting information about its owner and facts under investigation. This way, by means of exploring and cross referencing that rich data source, one can get information related to unlawful acts and its perpetrator. There are widespread and well documented approaches to forensic examining mobile devices and computers. Nevertheless, they are neither specific nor detailed enough to be conducted on Android cell phones. These approaches are not totally adequate to examine modern smartphones, since these devices have internal memories whose removal or mirroring procedures are considered invasive and complex, due to difficulties in having direct hardware access. The exam and analysis are not supported by forensic tools when having to deal with specific file systems, such as YAFFS2 (Yet Another Flash File System). Furthermore, specific features of each smartphone platform have to be considered prior to acquiring and analyzing its data. In order to deal with those challenges, this paper proposes a method to perform data acquisition and analysis of Android smartphones, regardless of version and manufacturer. The proposed approach takes into account existing techniques of computer and cell phone forensic examination, adapting them to specific Android characteristics, its data storage structure, popular applications and the conditions under which the device was sent to the forensic examiner. The method was defined in a broad manner, not naming specific tools or techniques. Then, it was deployed into the examination of six Android smartphones, which addressed different scenarios that an analyst might face, and was validated to perform an entire evidence acquisition and analysis.

a b s t r a c t 26The trust is always present implicitly in the protocols based on cooperation, in particular, between the 27 entities involved in routing operations in Ad hoc networks. Indeed, as the wireless range of such nodes 28 is limited, the nodes mutually cooperate with their neighbors in order to extend the remote nodes and 29 the entire network. In our work, we are interested by trust as security solution for OLSR protocol. This 30 approach fits particularly with characteristics of ad hoc networks. Moreover, the explicit trust manage-31 ment allows entities to reason with and about trust, and to take decisions regarding other entities. 32In this paper, we detail the techniques and the contributions in trust-based security in OLSR. We pres-33 ent trust-based analysis of the OLSR protocol using trust specification language, and we show how trust-

Graphene nanoribbons (GNRs) are two-dimensional structures with a rich variety of electronic properties that derive from their semiconducting band gaps. In these materials, charge transport can occur via a hopping process mediated by carriers formed by self-interacting states between the excess charge and local lattice deformations. Here, we use a two-dimensional tight-binding approach to reveal the formation of bipolarons in GNRs. Our results show that the formed bipolarons are dynamically stable even for high electric field strengths when it comes to GNRs. Remarkably, the bipolaron dynamics can occur in acoustic and optical regimes concerning its saturation velocity. The phase transition between these two regimes takes place for a critical field strength in which the bipolaron moves roughly with the speed of sound in the material.

In this paper, assuming an interference-limited eavesdropper scenario, the secrecy outage performance of multiple-input multiple-output wiretap channels with transmit antenna selection is investigated. Considering that the transmitter (Tx) and the receiver (Rx) are equipped with NA and NB antennas, respectively, while the passive eavesdropper is set with NE antennas, closed-form expressions for the secrecy outage probability and non-zero secrecy rate are derived. In our analysis, both maximal-ratio combining (MRC) and selection combining (SC) are employed at the Rx, while the eavesdropper uses a MRC scheme. The derived outage expressions hold for arbitrary power distributed jamming signals and some of their special cases (i.e., distinct power distributed and equal power distributed jamming signals) are presented. An asymptotic analysis is carried out to show the impact of the number of jamming signals and number of antennas on the secrecy outage performance. Interestingly, our results show that the diversity order equals to min(M, NANB), with M denoting the number of jamming signals. This allows us to conclude that the number of jamming signals at the eavesdropper limits the secrecy performance via diversity such that a high number of antennas does not imply necessarily in a performance improvement, unless for a large number of jamming signals.

We systematically investigate, at density functional theory level, the electronic properties of a set of ten carotenoid molecules with different conjugation length. Ground state geometries were fully optimized using both B3LYP and its long-range corrected version, i.e., the CAM-B3LYP functional. The time-dependent DFT approach (TD-DFT) was also performed for the calculation of the excited states of the optimized geometries and the results were compared to the experimental ones, when available. Our findings indicate a dependence of the transition vertical energies, oscillator strengths, and transition dipole moments on the extension of conjugation, as expected. We also investigate the impact of the intra-molecular vibrations on the absorption spectrum by means of the Franck-Condon (FC) and nuclear ensemble (NE) approach to spectra simulation. Our simulations suggest that the Franck-Condon approximation may not be suitable to appropriately characterize the vibronic progression of these molecules, whereas the NE approach provides a contribution that vary from negligible to meaningful depending on which molecule and energy region is under analysis.