Real-time computation of distance to dynamic obstacles with multiple depth sensors

We present an efficient method to evaluate distances between dynamic obstacles and a number of points of interests (e.g., placed on the links of a robot) when using multiple depth cameras. A depth-space oriented discretization of the Cartesian space is introduced that represents at best the workspace monitored by a depth camera, including occluded points. A depth grid map can be initialized off line from the arrangement of the multiple depth cameras, and its peculiar search characteristics allows fusing on line the information given by the multiple sensors in a very simple and fast way. The real-time performance of the proposed approach is shown by means of collision avoidance experiments where two Kinect sensors monitor a human-robot coexistence task

A Depth Space Approach for Evaluating Distance to Objects -- with Application to Human-Robot Collision Avoidance

We present a novel approach to estimate the distance between a generic point in the Cartesian space and objects detected with a depth sensor. This information is crucial in many robotic applications, e.g., for collision avoidance, contact point identification, and augmented reality. The key idea is to perform all distance evaluations directly in the depth space. This allows distance estimation by considering also the frustum generated by the pixel on the depth image, which takes into account both the pixel size and the occluded points. Different techniques to aggregate distance data coming from multiple object points are proposed. We compare the Depth space approach with the commonly used Cartesian space or Configuration space approaches, showing that the presented method provides better results and faster execution times. An application to human-robot collision avoidance using a KUKA LWR IV robot and a Microsoft Kinect sensor illustrates the effectiveness of the approach

Excess science accommodation capabilities and excess performance capabilities assessment for Mars Geoscience and Climatology Orbiter: Extended study

The excess science accommodation and excess performance capabilities of a candidate spacecraft bus for the Mars Geoscience and Climatology Orbiter MGCO mission are assessed. The appendices are included to support the conclusions obtained during this contract extension. The appendices address the mission analysis, the attitude determination and control, the propulsion subsystem, and the spacecraft configuration

Direct Mass Limits for Chiral Fourth-Generation Quarks in All Mixing Scenarios

Present limits on chiral fourth-generation quark masses $m_{b'}$ and $m_{t'}$ are broadly generalized and strengthened by combining both $t'$ and $b'$ decays and considering the full range of $t'$ and $b'$ flavor-mixing scenarios (with the lighter generations). Various characteristic mass-splitting choices are considered. With $m_{t'} > m_{b'}$ we find that CDF limits on the $b'$ mass vary by no more than 10-20% with any choice of flavor-mixing, while for the $t'$ mass, we typically find stronger bounds, in some cases up to $m_{t'} > 430$ GeV. For $m_{b'} > m_{t'}$ we find $m_{b'} > 380 - 430$ GeV, depending on the flavor-mixing and the size of the $m_{t'} - m_{b'}$ mass splitting

Anticorrelation between Ion Acceleration and Nonlinear Coherent Structures from Laser-Underdense Plasma Interaction

In laser-plasma experiments, we observed that ion acceleration from the Coulomb explosion of the plasma channel bored by the laser, is prevented when multiple plasma instabilities such as filamentation and hosing, and nonlinear coherent structures (vortices/post-solitons) appear in the wake of an ultrashort laser pulse. The tailoring of the longitudinal plasma density ramp allows us to control the onset of these insabilities. We deduced that the laser pulse is depleted into these structures in our conditions, when a plasma at about 10% of the critical density exhibits a gradient on the order of 250 {\mu}m (gaussian fit), thus hindering the acceleration. A promising experimental setup with a long pulse is demonstrated enabling the excitation of an isolated coherent structure for polarimetric measurements and, in further perspectives, parametric studies of ion plasma acceleration efficiency.Comment: 4 pages, 5 figure

Short Intense Laser Pulse Collapse in Near-Critical Plasma

It is observed that the interaction of an intense ultra-short laser pulse with an overdense gas jet results in the pulse collapse and the deposition of a significant part of energy in a small and well localized volume in the rising part of the gas jet, where the electrons are efficiently accelerated and heated. A collisionless plasma expansion over 150 microns at a sub-relativistic velocity (~c/3) has been optically monitored in time and space, and attributed to the quasistatic field ionization of the gas associated to the hot electron current. Numerical simulations in good agreement with the observations suggest the acceleration in the collapse region of relativistic electrons, along with the excitation of a sizeable magnetic dipole that sustains the electron current over several picoseconds. Perspectives of ion beam generation at high repetition rate directly from gas jets are discussed

Control of Redundant Robots Under Hard Joint Constraints: Saturation in the Null Space

We present an efficient method for addressing online the inversion of differential task kinematics for redundant manipulators, in the presence of hard limits on joint space motion that can never be violated. The proposed SNS (Saturation in the Null Space) algorithm proceeds by successively discarding the use of joints that would exceed their motion bounds when using the minimum norm solution. When processing multiple tasks with priority, the SNS method realizes a preemptive strategy by preserving the correct order of priority in spite of the presence of saturations. In the single- and multi-task case, the algorithm automatically integrates a least possible task scaling procedure, when an original task is found to be unfeasible. The optimality properties of the SNS algorithm are analyzed by considering an associated Quadratic Programming problem. Its solution leads to a variant of the algorithm, which guarantees optimality also when the basic SNS algorithm does not. Numerically efficient versions of these algorithms are proposed. Their performance allows real-time control of robots executing many prioritized tasks with a large number of hard bounds. Experimental results are reported

Voters care about government formation even when the landscape is fragmented and coalition signals are ambiguous or absent

Advocates of proportional representation often claim that a reformed electoral system would eliminate the need for tactical voting, along the lines we are currently seeing the UK general election. Drawing on evidence from Belgium, Tom Verthé, Stefanie Beyens, Fernanda Flacco, Louise Nikolic, argue that voters do care about government and coalition formation even when the political and electoral landscape is fragmented, and coalition signals are ambiguous or even absent

Generic versus brand-name cardiovascular drugs: a remarkable update

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Generic versus brand-name drugs used in cardiovascular diseases

This meta-analysis aimed to compare the efficacy and adverse events, either serious or mild/moderate, of all generic versus brand-name cardiovascular medicines. We searched randomized trials in MEDLINE, Scopus, EMBASE, Cochrane Controlled Clinical Trial Register, and ClinicalTrials.gov (last update December 1, 2014). Attempts were made to contact the investigators of all potentially eligible trials. Two investigators independently extracted and analyzed soft (including systolic blood pressure, LDL cholesterol, and others) and hard efficacy outcomes (including major cardiovascular adverse events and death), minor/moderate and serious adverse events. We included 74 randomized trials; 53 reported ≥1 efficacy outcome (overall sample 3051), 32 measured mild/moderate adverse events (n = 2407), and 51 evaluated serious adverse events (n = 2892). We included trials assessing ACE inhibitors (n = 12), anticoagulants (n = 5), antiplatelet agents (n = 17), beta-blockers (n = 11), calcium channel blockers (n = 7); diuretics (n = 13); statins (n = 6); and others (n = 3). For both soft and hard efficacy outcomes, 100 % of the trials showed non-significant differences between generic and brand-name drugs. The aggregate effect size was 0.01 (95 % CI -0.05; 0.08) for soft outcomes; -0.06 (-0.71; 0.59) for hard outcomes. All but two trials showed non-significant differences in mild/moderate adverse events, and aggregate effect size was 0.07 (-0.06; 0.20). Comparable results were observed for each drug class and in each stratified meta-analysis. Overall, 8 serious possibly drug-related adverse events were reported: 5/2074 subjects on generics; 3/2076 subjects on brand-name drugs (OR 1.69; 95 % CI 0.40-7.20). This meta-analysis strengthens the evidence for clinical equivalence between brand-name and generic cardiovascular drugs. Physicians could be reassured about prescribing generic cardiovascular drugs, and health care organization about endorsing their wider use