Chromatographic test facility. Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

Test facility to verify design concepts and mathematical models of chromatograph for atmospheric composition analysis of Mar

Reduction of chromatographic data and evaluation of a GC model

Gas chromatograph, mass spectrometer system for chemical and biochemical determinations on Mars, and data reduction progra

Universal conductance fluctuations in epitaxial GaMnAs ferromagnets: structural and spin disorder

Mesoscopic transport measurements reveal a large effective phase coherence length in epitaxial GaMnAs ferromagnets, contrary to usual 3d-metal ferromagnets. Universal conductance fluctuations of single nanowires are compared for epilayers with a tailored anisotropy. At large magnetic fields, quantum interferences are due to structural disorder only, and an unusual behavior related to hole-induced ferromagnetism is evidenced, for both quantum interferences and decoherence. At small fields, phase coherence is shown to persist down to zero field, even in presence of magnons, and an additional spin disorder contribution to quantum interferences is observed under domain walls nucleation.Comment: 15 pages, 4 figure

Anharmonicity and asymmetry of Landau levels for a two-dimensional electron gas

We calculate the density of states of a two dimensional electron gas located at the interface of a GaAlAs/GaAs heterojunction. The disorder potential which is generally created by a single doping layer behind a spacer, is here enhanced by the presence of a second delta doped layer of scatterers which can be repulsive or attractive impurities. We have calculated the density of states by means of the Klauder's approximation, in the presence of a magnetic field of arbitrary strength. At low field either band tails or impurity bands are observed for attractive potentials, depending on the impurity concentration. At higher field, impurity bands are observed for both repulsive and attractive potentials. We discuss the effect of such an asymmetrical density of states on the transport properties in the quantum Hall effect regime.Comment: 22 pages, 12 figures. submitted to Phys. Rev.

NIKEL: Electronics and data acquisition for kilopixels kinetic inductance camera

A prototype of digital frequency multiplexing electronics allowing the real time monitoring of microwave kinetic inductance detector (MKIDs) arrays for mm-wave astronomy has been developed. Thanks to the frequency multiplexing, it can monitor simultaneously 400 pixels over a 500 MHz bandwidth and requires only two coaxial cables for instrumenting such a large array. The chosen solution and the performances achieved are presented in this paper.Comment: 21 pages, 14 figure

THE CLINICAL SIGNIFICANCE OF TWO DIFFERENT ELECTROMYOGRAPHY NORMALISATION TECHNIQUES IN PATIENTS WITH ANTERIOR CRUCIATE LIGAMENT INSTABILITY DURING TREADMILL WALKING

The purpose of this study is to investigate the clinical outcome of two normalisation techniques in detecting neuromuscular alterations of the quadriceps muscles between injured and non-injured patients diagnosed with ACL knee instability in their right knee during repeated gait cycles on a treadmill. The ensemble average muscle activity of the vastus lateralis and vastus medialis were normalised to either MVC or maximal activation during the gait cycle in eight male and female subjects. Results indicate that the EMG normalised to MVC was more sensitive in detecting differences in activation between the vastus lateralis and vastus medialis than the normalisation to maximal activity during repeated strides. This study indicates the importance of choosing the appropriate normalisation technique when seeking a clinical outcome measure

Frustration and sound attenuation in structural glasses

Three classes of harmonic disorder systems (Lennard-Jones like glasses, percolators above threshold, and spring disordered lattices) have been numerically investigated in order to clarify the effect of different types of disorder on the mechanism of high frequency sound attenuation. We introduce the concept of frustration in structural glasses as a measure of the internal stress, and find a strong correlation between the degree of frustration and the exponent alpha that characterizes the momentum dependence of the sound attenuation $Gamma(Q)$$\simeq$$Q^\alpha$. In particular, alpha decreases from about d+1 in low-frustration systems (where d is the spectral dimension), to about 2 for high frustration systems like the realistic glasses examined.Comment: Revtex, 4 pages including 4 figure

Comparaison des diversités génétiques de Dacryodes edulis (G.Don) H.J. Lam et de Dacryodes buettneri (Engel.) H.J. Lam (Burséracées), deux espèces forestières utiles en Afrique centrale

Dacryodes buettneri et Dacryodes edulis sont des espèces à usages multiples en Afrique centrale. Elles servent principalement de bois d’oeuvre et de fruitier. Des échantillons de leurs folioles ont été récoltés sur 694 arbres répartis dans 29 populations au Cameroun et au Gabon, afin d’extraire l’ADNn et amplifier cinq marqueurs microsatellites. Les paramètres génétiques des populations ont été calculés pour évaluer et comparer leur diversité génétique. Les moyennes des nombres d’allèles sont respectivement 4,43 ± 1,37 et 5,36 ± 1,13. Il n’existe pas de différence significative dans la répartition des nombres d’allèles par locus entre les espèces. Les paramètres de la diversité intra-population de D. buettneri (P = 0,76 ± 0,15; Hatt = 0,35 ± 0,06 et Hobs = 0,26 ± 0,04) sont significativement inférieurs à ceux de D. edulis (P = 0,9 ± 0,12; Hatt = 0,47 ± 0,05 et Hobs = 0,41 ± 0,07), alors que le coefficient de consanguinité de D. buettneri (F = 0,25 ± 0,08) est deux fois supérieur à celui de la deuxième espèce (F = 0,12 ± 0,03). Un important flux de gènes inter-espèce a été trouvé, Nm = 0,44. Les analyses ont ressorti trois groupes de populations, séparés par la distance géographique et l’isolement taxonomique. D. edulis se croise parfaitement si les individus sont géographiquement proches, même avec les individus spontanés forestiers. Aucune séparation variétale au sein de D. edulis n’a été détectée. Cette étude est une contribution à la valorisation de la diversité génétique des espèces forestières africaines pour une conservation durable.Mots clés : Espèces à usages multiples, marqueurs microsatellites, génétique de populations, conservation durable

WHAT CAN WE LEARN FROM IN VIVO BIOMECHANICAL INVESTIGATIONS OF LOWER EXTREMITY?

In vivo biomechanical investigations of human movement are needed to better understand function and injury mechanism of the musculoskeletal system and to validate models or methods that otherwise could not be validated. In this report, we showcase two biomechanical approaches that use in vivo experiments to directly measure skin movement artefacts and the role of hamstring neuromuscular control in protecting the anterior cruciate ligament (ACL). The study on skin movement artefacts revealed that surface markers provided kinematics which can present repeatable patterns within a participant for various movements. However these repeatable patterns must not be misinterpreted as accurately representing skeletal kinematics, at least beyond the sagittal plane of movement. In the second investigation the neuromuscular control of the hamstring and gastrocnemius muscles showed a protective mechanism to prevent excessive ACL elongation, whereas the quadriceps muscles resisted against the collapsing of the knee joint after foot impact with the ground. This paper highlights the value of in vivo experimentation in contributing to our understanding of biomechanical functions or processes

Development of Lumped Element Kinetic Inductance Detectors for NIKA

Lumped-element kinetic inductance detectors(LEKIDs) have recently shown considerable promise as direct absorption mm-wavelength detectors for astronomical applications. One major research thrust within the N\'eel Iram Kids Array (NIKA) collaboration has been to investigate the suitability of these detectors for deployment at the 30-meter IRAM telescope located on Pico Veleta in Spain. Compared to microwave kinetic inductance detectors (MKID), using quarter wavelength resonators, the resonant circuit of a LEKID consists of a discrete inductance and capacitance coupled to a feedline. A high and constant current density distribution in the inductive part of these resonators makes them very sensitive. Due to only one metal layer on a silicon substrate, the fabrication is relatively easy. In order to optimize the LEKIDs for this application, we have recently probed a wide variety of individual resonator and array parameters through simulation and physical testing. This included determining the optimal feed-line coupling, pixel geometry, resonator distribution within an array (in order to minimize pixel cross-talk), and resonator frequency spacing. Based on these results, a 144-pixel Aluminum array was fabricated and tested in a dilution fridge with optical access, yielding an average optical NEP of ~2E-16 W/Hz^1/2 (best pixels showed NEP = 6E-17 W/Hz^1/2 under 4-8 pW loading per pixel). In October 2010 the second prototype of LEKIDs has been tested at the IRAM 30 m telescope. A new LEKID geometry for 2 polarizations will be presented. Also first optical measurements of a titanium nitride array will be discussed.Comment: 5 pages, 12 figures; ISSTT 2011 Worksho