Delivery actuator for a transcervical sterilization device

The use of delivery systems in the human body for positioning and deploying implants, such as closure devices, dilation balloons, stents, coils and sterilization devices, are gaining more importance to preclude surgical incisions and general anesthesia. The majorities of the non-surgical medical devices are delivered in a low profile into human body form and subsequently require specialized operations for their deployment and release. An analogous procedure for permanent female sterilization is the transcervical approach that does not require either general anesthesia or surgical incision and uses a normal body passage. The objective of this paper is to detail the design, development and verification of an ergonomic actuator for a medical application. In particular, this actuator is designed for the deployment and release of an implant to achieve instant permanent female sterilization via the transcervical approach. This implant is deployed under hysteroscopic visualization and requires a sequence of rotary and linear operations for its deployment and release. More specifically, this manually operated actuator is a hand held device designed to transmit the required forces in a particular sequence to effect both implant deployment and release at a target location. In order to design the actuator and to investigate its mechanical behavior, a three-dimensional (3D) Computer Aided Design (CAD) model was developed and Finite Element Method (FEM) was used for simulations and optimization. Actuator validation was performed following a number of successful bench-top in-air deployments and in-vitro deployments in animal tissue and explanted human uteri. During these deployments it was observed that the actuator applied the required forces to the implant resulting in successful deployment. Initial results suggest that this actuator can be used single handedly during the deployment phase. The ongoing enhancement of this actuator is moving towards “first-in- man” clinical trials

The GEO 600 laser system

Interferometric gravitational wave detectors require high optical power, single frequency lasers with very good beam quality and high amplitude and frequency stability as well as high long-term reliability as input light source. For GEO 600 a laser system with these properties is realized by a stable planar, longitudinally pumped 12 W Nd:YAG rod laser which is injection-locked to a monolithic 800 mW Nd:YAG non-planar ring oscillator. Frequency control signals from the mode cleaners are fed to the actuators of the non-planar ring oscillator which determines the frequency stability of the system. The system power stabilization acts on the slave laser pump diodes which have the largest influence on the output power. In order to gain more output power, a combined Nd:YAGNd:YVO4 system is scaled to more than 22 W

Pulsed energy-time entangled twin-photon source for quantum communication

A pulsed source of energy-time entangled photon pairs pumped by a standard laser diode is proposed and demonstrated. The basic states can be distinguished by their time of arrival. This greatly simplifies the realization of 2-photon quantum cryptography, Bell state analyzers, quantum teleportation, dense coding, entanglement swapping, GHZ-states sources, etc. Moreover the entanglement is well protected during photon propagation in telecom optical fibers, opening the door to few-photon applications of quantum communication over long distances.Comment: 8 pages, 4 figure

An analysis of the fluctuations of the geomagnetic dipole

The time evolution of the strength of the Earth's virtual axial dipole moment (VADM) is analyzed by relating it to the Fokker-Planck equation, which describes a random walk with VADM-dependent drift and diffusion coefficients. We demonstrate first that our method is able to retrieve the correct shape of the drift and diffusion coefficients from a time series generated by a test model. Analysis of the Sint-2000 data shows that the geomagnetic dipole mode has a linear growth time of 13 to 33 kyr, and that the nonlinear quenching of the growth rate follows a quadratic function of the type [1-(x/x0)^2]. On theoretical grounds, the diffusive motion of the VADM is expected to be driven by multiplicative noise, and the corresponding diffusion coefficient to scale quadratically with dipole strength. However, analysis of the Sint-2000 VADM data reveals a diffusion which depends only very weakly on the dipole strength. This may indicate that the magnetic field quenches the amplitude of the turbulent velocity in the Earth's outer core.Comment: 11 pages, 6 figure

Analysis of local Al-doped back surface fields for high efficiency screen-printed solar cells

AbstractIn this paper, we investigate the surface recombination of local screen-printed aluminum contacts applied to rear passivated solar cells. We measure the surface recombination velocity by microwave-detected photoconductance decay measurements on test wafers with various contact geometries and compare two different aluminum pastes. The aluminum paste which is optimized for local contacts shows a deep and uniform local back surface field that results in Smet=600cm/s on 1.5Ωcm p-type silicon. In contrast, a standard Al paste for full-area metallization shows a non-uniform back surface field and a Smet of 2000cm/s on the same material. We achieve an area-averaged rear surface recombination velocity Srear=(65±20) cm/s for line contacts with a pitch of 2mm. The application of the optimized paste to screen-printed solar cells with dielectric surface passivation results in efficiencies of up to 19.2% with a Voc=655mV and a Jsc=38.4mA/cm2 on 125×125 mm2 p-type Cz silicon wafers. The internal quantum efficiency analysis reveals Srear=(70±30) cm/s which is in agreement with our lifetime results. Applying fine line screen-printing, efficiencies up to 19.4% are demonstrated

Microgeographic adaptation and the effect of pollen flow on the adaptive potential of a temperate tree species

Recent interest for microgeographic adaptation, i.e. adaptation at spatial scales compatible with substantial amount of gene dispersal, offers to reconsider the scale at which evolution occurs (Richardson et al. 2014). Whether gene flow is constraining or facilitating local adaptation at this fine spatial scale remains an unresolved question. Too important gene flow would overwhelm the effects of natural selection and decrease local adaptation along environmental gradients. Conversely, gene flow, and particularly long-distance dispersal events, could play a major role in resupplying the genetic variation of populations and favouring the spread of beneficial alleles (Kremer et al. 2012). Hence, the high dispersal capacities of trees are often assumed to be the main process maintaining the large levels of genetic variation measured in their natural populations. However, evidences for microgeographic adaptation and the quantitative assessment of the impact of gene flow on adaptive genetic variation are still limited in most temperate trees. Here, we sampled 60 open-pollinated families of European beech (Fagus sylvatica L.) from three natural plots, spreading along a short elevation gradient (∼1.5 km) at the warm margin of this species distribution. We analysed the phenotypic and genotypic data of ∼2,300 seedlings grown in a common garden. We focused on 11 potentially adaptive traits with significant heritabilities (Gauzere et al. 2016) and tested for signature of local selection on quantitative trait differentiation. We then identified the offspring likely originating from local or distant pollen immigration events and quantified the role of gene flow in increasing locally the additive variance of traits under selection. We found a significant signal of adaptive differentiation among plots separated by less than one kilometre, with local selection acting on growth and phenological traits. We found that trees in the plots at high elevation, experiencing the lowest temperature conditions, flushed earlier and had a higher height and diameter growth in our common garden than trees from the plot at low elevation. Beech populations originating from higher longitude or elevation have also been shown to be genetically earlier in provenance tests, suggesting that these populations evolved phenological traits promoting a longer vegetation period. At this southern margin of the species, the reduced allocation to stem growth at the low elevation plot is likely an adaptive response to drought, which has previously been described by comparing marginal vs central beech populations. Consistently with theoretical expectations, our results suggest a beneficial effect of pollen dispersal by increasing the genetic diversity for these locally differentiated traits. These effects were quantitatively high, with more than twice higher genetic variance for immigrant than local offspring, although with large standard errors around estimates. Our results highlight that local selection is an important evolutionary force in natural tree populations, and provide a strong evidence that adaptive genetic differentiation can occur despite high gene flow. For the two genetically differentiated traits, our analyses suggested a beneficial effect of pollen dispersal by increasing genetic diversity after one episode of reproduction. The findings suggest that conservation and management interventions to facilitate movement of gametes along short ecological gradients would boost genetic diversity of individual tree populations, and thereby enhance their adaptive potential