Resonance and marginal instability of switching systems

We analyse the so-called Marginal Instability of linear switching systems, both in continuous and discrete time. This is a phenomenon of unboundedness of trajectories when the Lyapunov exponent is zero. We disprove two recent conjectures of Chitour, Mason, and Sigalotti (2012) stating that for generic systems, the resonance is sufficient for marginal instability and for polynomial growth of the trajectories. We provide a characterization of marginal instability under some mild assumptions on the sys- tem. These assumptions can be verified algorithmically and are believed to be generic. Finally, we analyze possible types of fastest asymptotic growth of trajectories. An example of a pair of matrices with sublinear growth is given

Comparative Analysis of Patch Lesions in the Chick Inner Ear Following Acoustic Trauma: Optical Versus Scanning Electron Microscopy

Neonatal chicks were exposed to an octave band noise with a center frequency of 1.5 kHz at 116 dB SPL for 4 hours. Seven days following overstimulation, the birds were sacrificed. Their basilar papillae were re-moved, fixed in 4% paraformaldehyde, and processed in two steps. First, the ears were immunostained with a supernatant of mouse anti-tectorial membrane antibodies, followed by a diaminobenzidine process. Examinations of the papillae under an optical stereo microscope revealed a patch site with a partially regenerated tectorial membrane (referred to as the honeycomb). After the optical studies, the same ears were post-fixed in 1% osmium tetroxide, dehydrated in ethanol, and processed for scanning electron microscopy (SEM). SEM examinations demonstrated a honeycomb-covered patch lesion in the papilla. Patch lesion perimeters were traced from both the optical and SEM images, and patch areas were calculated. Also, papilla height was measured at the midpoint of the inner ear in both groups. These calculations showed that the patch area and papilla height had shrunk by approximately 37% and 33% , respectively, following the SEM methodology. The decrease in these dimensions may be attributed to several steps required for the SEM specimen preparation, such as critical point drying

Stellar Evolution Constraints on the Triple-Alpha Reaction Rate

We investigate the quantitative constraint on the triple-alpha reaction rate based on stellar evolution theory, motivated by the recent significant revision of the rate proposed by nuclear physics calculations. Targeted stellar models were computed in order to investigate the impact of that rate in the mass range of 0.8 < M / Msun < 25 and in the metallicity range between Z = 0 and Z = 0.02. The revised rate has a significant impact on the evolution of low- and intermediate-mass stars, while its influence on the evolution of massive stars (M >~ 10 Msun) is minimal. We find that employing the revised rate suppresses helium shell flashes on AGB phase for stars in the initial mass range 0.8 < M / Msun < 6, which is contradictory to what is observed. The absence of helium shell flashes is due to the weak temperature dependence of the revised triple-alpha reaction cross section at the temperature involved. In our models, it is suggested that the temperature dependence of the cross section should have at least nu > 10 at T = 1 - 1.2 x 10^8 K where the cross section is proportional to T^{nu}. We also derive the helium ignition curve to estimate the maximum cross section to retain the low-mass first red giants. The semi-analytically derived ignition curves suggest that the reaction rate should be less than ~ 10^{-29} cm^6 s^{-1} mole^{-2} at ~ 10^{7.8} K, which corresponds to about three orders of magnitude larger than that of the NACRE compilation. In an effort to compromise with the revised rates, we calculate and analyze models with enhanced CNO cycle reaction rates to increase the maximum luminosity of the first giant branch. However, it is impossible to reach the typical RGB tip luminosity even if all the reaction rates related to CNO cycles are enhanced by more than ten orders of magnitude.Comment: 14 pages, 8 figures, accepted by the Ap

Mixed Mucinous Carcinoma of the Male Breast

Male breast malignancy is extremely rare, representing less than 1% of all breast carcinomas. Infiltrating duct carcinoma is the commonest subtype. Pure mucinous carcinoma and mixed mucinous carcinoma wherein there are components of both mucinous carcinoma and infiltrating duct carcinoma are rare tumours constituting 1.5-5% in women and are even rarer in men. We present here a case of mixed mucinous carcinoma of the breast with metastasis to axillary lymph nodes in a male patient

The Effects of Goal Orientation and Learning Strategies on Managerial Job Performance

The purpose of this study was to test a theoretical model of the role of informal managerial learning processes in predicting job performance. Using Goal Orientation (GO) as a framework, this study tested the relationships between dispositional GO, learning strategies, and organizational and managerial support in relation to job performance. Participants were 143 employees across several global regions in an insurance firm. Overall, path analyses indicated that dispositional mastery GO was positively associated with learning strategies and job performance. Contrary to hypotheses, the learning strategies did not positively predict job performance. Differential effects were found for the influence of organizational and managerial support on learning strategies as organizational was found to positively predict active feedback seeking and negatively predict effort regulation, while managerial support negatively predicted active feedback seeking. Research and organizational implications are discussed

Une ingénierie éducative innovante pour travailler des compétences en EDD dans le cadre d'un Observatoire Hommes Milieux

International audienceNous présentons un dispositif qui engage des relations entre chercheurs, enseignants et élèves dans un territoire partagé. Un Observatoire Hommes Milieux permet d'appréhender la complexité, l'incertitude, les savoirs en construction et la projection vers le(s) futur(s) possible(s), compétences centrales en éducation au développement durable. Des jeux de rôle ont été proposés à travers la co-construction de séquences pédagogiques par des chercheurs et des enseignants, et des dispositifs pédagogiques variés tels que des sorties, des débats et des rencontres avec des chercheurs et des acteurs du territoire. Les élèves se sont confrontés à une certaine complexité en manipulant des temporalités : observation de co-évolutions hommes-milieux dans le passé et projection dans le futur par exemple. En retour, les acquis de ce travail visaient à développer chez les élèves des capacités à réinvestir hors de l' école ce qu'ils ont vu en classe. C' est un enjeu fort de la contribution des activités scolaires à l' éducation citoyenne

Pressure Dependence of the Irreversibility Line in Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta}:Role of Anisotropy in Flux-Line Formation

One of the important problems of high-temperature superconductivity is to understand and ultimately to control fluxoid motion. We present the results of a new technique for measuring the pressure dependence of the transition to superconductivity in a diamond anvil cell. By measuring the third harmonic of the {\it ac} susceptibility, we determine the onset of irreversible flux motion. This enables us to study the effects of pressure on flux motion. The application of pressure changes interplanar spacing, and hence the interplanar coupling, without significantly disturbing the intraplanar superconductivity. Thus we are able to separate the effects of coupling from other properties that might affect the flux motion. Our results directly show the relationship between lattice spacing, effective- mass anisotropy, and the irreversibility line in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$. Our results also demonstrate that an application of 2.5 GPa pressure causes a dramatic increase in interplanar coupling.Comment: 4 pages, 4 figure