Young-type interferences using single-electron sources and an atomic-size two-center interferometer: Dependence with interferometer parameters

We present the realization of a Young-type double-slit experiment, in which single electrons, scattering on two protons, produce interference pattern. The electrons are produced by a Auger effect, following double capture process in low He²⁺ + H₂ collisions. Well-defined oscillations are visible in the angular distribution of the electrons emitted towards the receding protons. The presence of these oscillations is a clear demonstration that an electron interferes with itself. We also discuss the dependence of the interference pattern with interference parameters, such as the electron wavelength as well as the distance between the protons when the electron is ejected.     

Synthesis,Biological Evaluation of 1,1‐Diarylethylenes as a Novel Class of Antimitotic Agents

The cytotoxic activities of 23 new isocombretastatin A derivatives with modifications on the B‐ring were investigated. Several compounds exhibited excellent antiproliferative activity at nanomolar concentrations against a panel of human cancer cell lines. Compounds isoFCA‐4 ( 2 e ), isoCA‐4 ( 2 k ) and isoNH₂CA‐4 ( 2 s ) were the most cytotoxic, and strongly inhibited tubulin polymerization with IC₅₀ values of 4, 2 and 1.5 μM , respectively. These derivatives were found to be 10‐fold more active than phenstatin and colchicine with respect to growth inhibition but displayed similar activities as tubulin polymerization inhibitors. In addition, cell cycle arrest in the G₂/M phase and subsequent apoptosis was observed in three cancer cell lines when treated with these compounds. The disruptive effect of 2 e , 2 k and 2 s on the vessel‐like structures formed by human umbilical vein endothelial cells (HUVEC) suggest that these compounds may act as vascular disrupting agents. Both compounds 2 k and 2 s have the potential for further prodrug modification and development as vascular disrupting agents for treatment of solid tumors.     

Yardstick competition: which neighbours matter?

This paper aims at testing the existence of yardstick competition by estimating a fully specified vote-function on a panel data set of 104 French local governments from 1989 to 2001. When comparing the performance of their incumbent to the one of their “neighbours”, voters might consider their close geographical neighbours but also the nearby cities that are similar according to some socio-economic characteristics such as population size. The estimation results show that voters sanction their incumbent if their own local housing tax is high. Moreover, we find that voters reward their incumbent when neighbouring cities that are similar in terms of demographic characteristics have high local taxes.     

Gas migration properties through a bentonite/argillite interface

Among diversified industrial uses, see for instance Koch [Koch, Appl. Clay Sci., (21) 2002], and following positive in situ experiments, compacted bentonite blocks are potential candidates for sealing nuclear waste repositories, thanks to their swelling ability in a wet environment.As requested by Andra (French Agency for Nuclear Waste Management) and complementarily to in situ experiments, an original experimental laboratory set-up was designed in order to reproduce the introduction and swelling of bentonite plugs inside an argillite host rock. Once the argillite/bentonite interface is established, an increase in storage tunnel gas pressure is simulated and the interface gas migration pressure (or gas critical pressure) is evaluated. More precisely, a first experimental set-up provides bentonite swelling pressure and kinetics (i.e. mainly hydraulic cut-off, time to reach asymptotic swelling pressure and value of asymptotic swelling pressure) at given initial compaction and saturation rate. This phase is preparatory to reproducing the introduction and subsequent swelling of a bentonite plug inside the argillite host rock, which uses a similar test rig. Experimental results of water permeability and gas critical pressure are provided for MX80 compacted bentonite associated to Bure Callovo-Oxfordian argillite.     

High-resolution full-field optical coherence tomography with a Linnik microscope

We describe an original microscope for high-resolution optical coherence tomography applications. Our system is based on a Linnik interference microscope with high-numerical-aperture objectives. Lock-in detection of the interference signal is achieved in parallel on a CCD by use of a photoelastic birefringence modulator and full-field stroboscopic illumination with an infrared LED. Transverse cross-section (en-face, or XY) images can be obtained in real time with better than 1-microm axial (Z) resolution and 0.5-microm transverse (XY) resolution. A sensitivity of approximately 80 dB is reached at a 1-image/s acquisition rate, which allows tomography in scattering media such as biological tissues.     

Reduction of the correlation sensitivity to the changes of the input illumination by a post processing based on the correlation statistics

Linear-correlation amplitude changes when the intensity level of the input image is modified. As recognition is often based on the correlation-peak level, a change of the input illumination may result in a false recognition. We propose an illumination-change compensation by a post processing of the correlation distribution that is based on statistical measures of the correlation histograms. The theoretical background and simulation results are provided in the frame of an actual application in biology.     

Moving address translation closer to memory in distributed shared-memory multiprocessors

To support a global virtual memory space, an architecture must translate virtual addresses dynamically. In current processors, the translation is done in a TLB (translation lookaside buffer), before or in parallel with the first-level cache access. As processor technology improves at a rapid pace and the working sets of new applications grow insatiably, the latency and bandwidth demands on the TLB are difficult to meet, especially in multiprocessor systems, which run larger applications and are plagued by the TLB consistency problem. We describe and compare five options for virtual address translation in the context of distributed shared memory (DSM) multiprocessors, including CC-NUMAs (cache-coherent non-uniform memory access architectures) and COMAs (cache only memory access architectures). In CC-NUMAs, moving the TLB to shared memory is a bad idea because page placement, migration, and replication are all constrained by the virtual page address, which greatly affects processor node access locality. In the context of COMAs, the allocation of pages to processor nodes is not as critical because memory blocks can dynamically migrate and replicate freely among nodes. As the address translation is done deeper in the memory hierarchy, the frequency of translations drops because of the filtering effect. We also observe that the TLB is very effective when it is merged with the shared-memory, because of the sharing and prefetching effects and because there is no need to maintain TLB consistency. Even if the effectiveness of the TLB merged with the shared memory is very high, we also show that the TLB can be removed in a system with address translation done in memory because the frequency of translations is very low.     

Computational methods for determining the latest starting times and floats of tasks in interval-valued activity networks

In project management, three quantities are often used by project managers: the earliest starting date, the latest starting date and the float of tasks. These quantities are computed by the Program Evaluation and Review Techniques/Critical Path Method (PERT/CPM) algorithm. When task durations are ill known, as is often the case at the beginning of a project, they can be modeled by means of intervals, representing the possible values of these task durations. With such a representation, the earliest starting dates, the latest starting dates and the floats are also intervals. The purpose of this paper is to give efficient algorithms for their computation. After recalling the classical PERT/CPM problem, we present several properties of the concerned quantities in the interval-valued case, showing that the standard criticality analysis collapses. We propose an efficient algorithm based on path enumeration to compute optimal intervals for latest starting times and floats in the general case, and a simpler polynomial algorithm in the case of series-parallel activity networks.     

Structure and tribological property of B2-based approximants

The present paper is concerned with a special group of approximants with B2 superstructures. In the first part, recent work on structural features of the B2 superstructure approximants is summarized. Experimental results obtained in Al-Cu-Mn and Al-Cu systems are presented, where a series of B2-based approximants are observed. These phases all have similar valence electron concentrations, in full support of thee/a-constant definition of approximants. Special emphasis is laid on the chemical twinning modes of the B2 basic structure in relation to the Al-Cu approximants. It is revealed that the B2 twinning mode responsible for the formation of local pentagonal atomic arrangements is of 180°/[111] type. This is also the origin of 5-fold twinning of the B2 phase on quasicrystal surfaces. Crystallographic features of phases B2, τ2, τ3,γ, and other newly discovered phases are also discussed. In all these phases, local pentagonal configurations are revealed. In the second part, dry tribological properties of some AlCuFe samples containing the B2-type phases are presented. The results indicated that the B2 phase having their valence ratio near that of the quasicrystal possesses low friction coefficient under various loads, comparable with the annealed quasicrystalline ingot. Such a result indicates that the B2-type phase withe/a near that of quasicrystal is indeed an approximant, which is in full support of the valence electron criterion for approximants.