Improved depth recovery in consumer depth cameras via disparity space fusion within cross-spectral stereo.

We address the issue of improving depth coverage in consumer depth cameras based on the combined use of cross-spectral stereo and near infra-red structured light sensing. Specifically we show that fusion of disparity over these modalities, within the disparity space image, prior to disparity optimization facilitates the recovery of scene depth information in regions where structured light sensing fails. We show that this joint approach, leveraging disparity information from both structured light and cross-spectral sensing, facilitates the joint recovery of global scene depth comprising both texture-less object depth, where conventional stereo otherwise fails, and highly reflective object depth, where structured light (and similar) active sensing commonly fails. The proposed solution is illustrated using dense gradient feature matching and shown to outperform prior approaches that use late-stage fused cross-spectral stereo depth as a facet of improved sensing for consumer depth cameras

Les historiens grecs entre la cité et l'exil

International audienceIn his treatise How to write history Lucian states that «in his books» the historian should be «a foreigner and a man without a country, independent, subject to no sovereign». This statement is not a sophistic paradox. It comes from a long traditionregarding Greek historians, which considers a biographical accident – the situation of exile – as a necessary condition for historical inquiry. This paper aims at reconstructing this tradition, from Herodotus to Arrian, and at showing it to be one of the most important paradigms of historical knowledge

Worldwide Needs for Safe Drinking Water Are Underestimated: Billions of People Are Impacted

An official statistic from the United Nations at the end of 2008 was that 884 million people lacked access to "improved" water sources. But many unaware of the precise meaning behind "improved", and indeed even the UN General Assembly itself, have convinced the public that 884 million is the number of people who lack access to safe water. The author argues that this is a serious underestimation. Not only does "improved" not ensure potability, it also fails to incorporate all aspects of the right to water. Furthermore, the question of access can not easily be answered with a yes or no; different modes of access may be more or less satisfactory. Shedding light on the order of magnitude truly involved in the water problem, this report provides rough estimates of the number of people whose right to safe drinking water is inadequately met

Ionospheric Behavior During Descendant Phase of Solar Cycle 20

This study describes the behavior of the peak value of the ionospheric concentration (foF2) during the descending phase of Solar Cycle 20. In order to understand the ionospheric dependency with the solar activity during the descending phase of solar cycle 20 (1970 to 1975), peak ionospheric values for multiple ionospheric stations have been downloaded from the National Oceanic and atmospheric Administration (NOAA)’s National Geophysics Data Center (NGDC) database and analyzed using a new approach: The study of daily maximum and minimum values. Many interesting characteristics of the ionospheric behavior were detected, while the trend of the maxima closely follows the trend of the solar activity (as captured by different indexes), the trend of the minima is 2 – 4 times less pronounced. The variability of both values seems to be consistently linked with the solar activity trend, but the clear picture does not emerge from this analysis. In order to clarify these trends, we plan to continue the exploration of the multiple dependencies of the ionospheric behavior with the solar activity

Topological Background Fields as Quantum Degrees of Freedom of Compactified Strings

It is shown that background fields of a topological character usually introduced as such in compactified string theories correspond to quantum degrees of freedom which parametrise the freedom in choosing a representation of the zero mode quantum algebra in the presence of non-trivial topology. One consequence would appear to be that the values of such quantum degrees of freedom, in other words of the associated topological background fields, cannot be determined by the nonperturbative string dynamics.Comment: 1+10 pages, no figure

Unconventional antiferromagnetic correlations of the doped Haldane gap system Y2_2BaNi1−x_{1-x}Znx_xO5_5

We make a new proposal to describe the very low temperature susceptibility of the doped Haldane gap compound Y$_2$BaNi$_{1-x}$Zn$_x$O$_5$. We propose a new mean field model relevant for this compound. The ground state of this mean field model is unconventional because antiferromagnetism coexists with random dimers. We present new susceptibility experiments at very low temperature. We obtain a Curie-Weiss susceptibility $\chi(T) \sim C / (\Theta+T)$ as expected for antiferromagnetic correlations but we do not obtain a direct signature of antiferromagnetic long range order. We explain how to obtain the ``impurity'' susceptibility $\chi_{imp}(T)$ by subtracting the Haldane gap contribution to the total susceptibility. In the temperature range [1 K, 300 K] the experimental data are well fitted by $T \chi_{imp}(T) = C_{imp} (1 + T_{imp}/T )^{-\gamma}$. In the temperature range [100 mK, 1 K] the experimental data are well fitted by $T \chi_{imp}(T) = A \ln{(T/T_c)}$, where $T_c$ increases with $x$. This fit suggests the existence of a finite N\'eel temperature which is however too small to be probed directly in our experiments. We also obtain a maximum in the temperature dependence of the ac-susceptibility $\chi'(T)$ which suggests the existence of antiferromagnetic correlations at very low temperature.Comment: 19 pages, 17 figures, revised version (minor modifications