Steinernema oregonensis n. sp. (Rhabditida : Steinernematidae) from Oregon, USA

Une nouvelle espèce du genre #Steinernema a été découverte près de Grant's Pass en Orégon. #Steinernema oregonensis n. sp. se distingue des autres espèces de #Steinernema par la longueur des juvéniles infestants, la forme des spicules, l'absence de mucron caudal chez les mâles de première génération, et sa présence chez les mâles de seconde génération. La longueur des juvéniles infestants est de 816 à 1112 micromètres, séparant #S. oregonensis n. sp. des autres espèces décrites de #Steinernema, sauf #S. affinis, #S. anomali, #S. feltiae, #S. glaseri, #S. neocurtilis, et #S. puertoricensis. La forme des spicules et l'absence de mucron caudal chez les mâles de première génération séparent #S. oregonensis de ces dernières espèces. Les rapports "d" et "e" sont, chez les juvéniles infestants, de 0,4 à 0,6 et 0,9 à 1,1 respectivement, séparant la nouvelle espèce de #S. cubana, #S. glaseri, #S. neocurtillis, et #S. puertoricensis. L'analyse de l'ADN de #S. oregonensis n. sp. montre un polymorphisme de longueur des fragments amplifiés au hasard différent de ceux de quatre autres espèces de #Steinernema. #S. oregonensis ne s'hybride pas avec les espèces proches #S. anomali, #S. feltiae, ou #S. glaseri. (Résumé d'auteur

Phylogenetic analysis of the genus Steinernema by morphological characters and randomly amplified polymorphic DNA fragments

Des caractères morphologiques et la longueur de fragments d'ADN amplifiés au hasard (RAPD) ont été utilisés pour réaliser une analyse phylogénique des nématodes entomopathogènes du genre #Steinernema. Les résultats concernant les relations phylogéniques entre espèces de #Steinernema fondées sur différentes bases de données n'ont pas été concluants. Les fragments de RAPD ont correctement séparé les espèces, mais la divergence entre espèces est si importante que cette analyse n'a apporté que peu d'information sur les relations phylogéniques entre espèces. Néanmoins, les fragments de RAPD peuvent être utilisés pour étudier la phylogénie des populations d'une même espèce car nombre de fragments de RAPD communs ont été trouvés parmi les populations d'une même espèce. La phylogénie déduite des caractères morphologiques est similaire à celle déduite de l'analyse de polymorphisme de fragments d'ADN ribosomal. Le rapport D (distance de l'avant au pore excréteur divisée par la distance de l'avant à la base du pharynx) chez les mâles et les juvéniles infestants montre un index de consistance individuelle de 1, ce qui pourrait se révéler important pour l'évaluation de la phylogénie. (Résumé d'auteur

Optical properties of tissue measured using terahertz pulsed imaging.

The first demonstrations of terahertz imaging in biomedicine were made several years ago, but few data are available on the optical properties of human tissue at terahertz frequencies. A catalogue of these properties has been established to estimate variability and determine the practicality of proposed medical applications in terms of penetration depth, image contrast and reflection at boundaries. A pulsed terahertz imaging system with a useful bandwidth 0.5-2.5 THz was used. Local ethical committee approval was obtained. Transmission measurements were made through tissue slices of thickness 0.08 to 1 mm, including tooth enamel and dentine, cortical bone, skin, adipose tissue and striated muscle. The mean and standard deviation for refractive index and linear attenuation coefficient, both broadband and as a function of frequency, were calculated. The measurements were used in simple models of the transmission, reflection and propagation of terahertz radiation in potential medical applications. Refractive indices ranged from 1.5 ± 0.5 for adipose tissue to 3.06 ± 0.09 for tooth enamel. Significant differences (P<0.05) were found between the broadband refractive indices of a number of tissues. Terahertz radiation is strongly absorbed in tissue so reflection imaging, which has lower penetration requirements than transmission, shows promise for dental or dermatological applications

Weyl formulas for annular ray-splitting billiards

We consider the distribution of eigenvalues for the wave equation in annular (electromagnetic or acoustic) ray-splitting billiards. These systems are interesting in that the derivation of the associated smoothed spectral counting function can be considered as a canonical problem. This is achieved by extending a formalism developed by Berry and Howls for ordinary (without ray-splitting) billiards. Our results are confirmed by numerical computations and permit us to infer a set of rules useful in order to obtain Weyl formulas for more general ray-splitting billiards

Fundamental solution method applied to time evolution of two energy level systems: exact and adiabatic limit results

A method of fundamental solutions has been used to investigate transitions in two energy level systems with no level crossing in a real time. Compact formulas for transition probabilities have been found in their exact form as well as in their adiabatic limit. No interference effects resulting from many level complex crossings as announced by Joye, Mileti and Pfister (Phys. Rev. {\bf A44} 4280 (1991)) have been detected in either case. It is argued that these results of this work are incorrect. However, some effects of Berry's phases are confirmed.Comment: LaTeX2e, 23 pages, 8 EPS figures. Style correcte

The Localization of ss-Wave and Quantum Effective Potential of a Quasi-Free Particle with Position-Dependent Mass

The properties of the s-wave for a quasi-free particle with position-dependent mass(PDM) have been discussed in details. Differed from the system with constant mass in which the localization of the s-wave for the free quantum particle around the origin only occurs in two dimensions, the quasi-free particle with PDM can experience attractive forces in $D$ dimensions except D=1 when its mass function satisfies some conditions. The effective mass of a particle varying with its position can induce effective interaction which may be attractive in some cases. The analytical expressions of the eigenfunctions and the corresponding probability densities for the s-waves of the two- and three-dimensional systems with a special PDM are given, and the existences of localization around the origin for these systems are shown.Comment: 12pages, 8 figure

The window period of NEUROGENIN3 during human gestation

The basic helix-loop-helix transcription factor, NEUROG3, is critical in causing endocrine commitment from a progenitor cell population in the developing pancreas. In human, NEUROG3 has been detected from 8 weeks postconception (wpc). However, the profile of its production and when it ceases to be detected is unknown. In this study we have defined the profile of NEUROG3 detection in the developing pancreas to give insight into when NEUROG3- dependent endocrine commitment is possible in the human fetus. Immunohistochemistry allowed counting of cells with positively stained nuclei from 7 wpc through to term. mRNA was also isolated from sections of human fetal pancreas and NEUROG3 transcription analyzed by quantitative reverse transcription and polymerase chain reaction. NEUROG3 was detected as expected at 8 wpc. The number of NEUROG3-positive cells increased to peak levels between 10 wpc and 14 wpc. It declined at and after 18 wpc such that it was not detected in human fetal pancreas at 35-41 wpc. Analysis of NEUROG3 transcription corroborated this profile by demonstrating very low levels of transcript at 35-41 wpc, more than 10-fold lower than levels at 12-16 wpc. These data define the appearance, peak and subsequent disappearance of the critical transcription factor, NEUROG3, in human fetal pancreas for the first time. By inference, the window for pancreatic endocrine differentiation via NEUROG3 action opens at 8 wpc and closes between 21 and 35 wpc

Spectral simplicity and asymptotic separation of variables

We describe a method for comparing the real analytic eigenbranches of two families of quadratic forms that degenerate as t tends to zero. One of the families is assumed to be amenable to `separation of variables' and the other one not. With certain additional assumptions, we show that if the families are asymptotic at first order as t tends to 0, then the generic spectral simplicity of the separable family implies that the eigenbranches of the second family are also generically one-dimensional. As an application, we prove that for the generic triangle (simplex) in Euclidean space (constant curvature space form) each eigenspace of the Laplacian is one-dimensional. We also show that for all but countably many t, the geodesic triangle in the hyperbolic plane with interior angles 0, t, and t, has simple spectrum.Comment: 53 pages, 2 figure

AUTSEG: Automatic Test Set Generator for Embedded Reactive Systems

Part 2: Tools and FrameworksInternational audienceOne of the biggest challenges in hardware and software design is to ensure that a system is error-free. Small errors in reactive embedded systems can have disastrous and costly consequences for a project. Preventing such errors by identifying the most probable cases of erratic system behavior is quite challenging. In this paper, we introduce an automatic test set generator called AUTSEG. Its input is a generic model of the target system, generated using the synchronous approach. Our tool finds the optimal preconditions for restricting the state space of the model. It only works locally on significant subspaces. Our approach exhibits a simpler and efficient quasi-flattening algorithm than existing techniques and a useful compiled form to check security properties and reduce the combinatorial explosion problem of state space. To illustrate our approach, AUTSEG was applied to the case of a transportation contactless card

Quantum Hall effect in a p-type heterojunction with a lateral surface quantum dot superlattice

The quantization of Hall conductance in a p-type heterojunction with lateral surface quantum dot superlattice is investigated. The topological properties of the four-component hole wavefunction are studied both in r- and k-spaces. New method of calculation of the Hall conductance in a 2D hole gas described by the Luttinger Hamiltonian and affected by lateral periodic potential is proposed, based on the investigation of four-component wavefunction singularities in k-space. The deviations from the quantization rules for Hofstadter "butterfly" for electrons are found, and the explanation of this effect is proposed. For the case of strong periodic potential the mixing of magnetic subbands is taken into account, and the exchange of the Chern numbers between magnetic subands is discussed.Comment: 12 pages, 5 figures; reported at the 15th Int. Conf. on High Magnetic Fields in Semicond. Phys. (Oxford, UK, 2002