Showing papers on "Measure (physics) published in 2006"

Beyond Rayleigh's criterion: A resolution measure with application to single-molecule microscopy

Abstract: Rayleigh's criterion is extensively used in optical microscopy for determining the resolution of microscopes. This criterion imposes a resolution limit that has long been held as an impediment for studying nanoscale biological phenomenon through an optical microscope. However, it is well known that Rayleigh's criterion is based on intuitive notions. For example, Rayleigh's criterion is formulated in a deterministic setting that neglects the photon statistics of the acquired data. Hence it does not take into account the number of detected photons, which, in turn, raises concern over the use of Rayleigh's criterion in photon-counting techniques such as single-molecule microscopy. Here, we re-examine the resolution problem by adopting a stochastic framework and present a resolution measure that overcomes the limitations of Rayleigh's criterion. This resolution measure predicts that the resolution of optical microscopes is not limited and that it can be improved by increasing the number of detected photons. Experimental verification of the resolution measure is carried out by imaging single-molecule pairs with different distances of separation. The resolution measure provides a quantitative tool for designing and evaluating single-molecule experiments that probe biomolecular interactions.

Displacement: a review of the empirical literature

Abstract: This paper reviews 55 published articles on crime prevention measures In which researchers specifically looked for evidence of displacement These articles are classified by the type of crime prevented and the nature of the preventive measure. Analysis of the evidence suggests that displacement Is not Inevitable, and that If displacement occurs, It will be limited In scope.

Method and apparatus for managing performance of multiple games

Abstract: In accordance with one or more embodiments, a method for managing games for use on gaming devices is presented, wherein the method comprises determining a measure of performance of a game, and determining a payment due to a provider of the game based on the measure of performance of the game. In one or more embodiments, the measure of performance may be used to determine whether to keep the game enabled on one or more gaming devices.

On the measure of digital terrain model accuracy

Abstract: In digital terrain model (DTM) production, one important concern is the accuracy and a comprehensive measure of DTM accuracy is of significance. In this paper, the existing measures are evaluated; the potential measures are also discussed and, finally, a more comprehensive measure is recommended.

A Confidence Measure for Variational Optic flow Methods

Abstract: In this paper we investigate the usefulness of confidence measures for variational optic flow computation. To this end we discuss the frequently used sparsification strategy based on the image gradient. Its drawbacks motivate us to propose a novel, energy-based confidence measure that is parameter-free and applicable to the entire class of energy minimising optic flow techniques. Experimental evaluations show that this confidence measure leads to excellent results, independently of the image sequence or the underlying variational approach.

Degradation of a quantum reference frame

Abstract: We investigate the degradation of reference frames (RFs), treated as dynamical quantum systems, and quantify their longevity as a resource for performing tasks in quantum information processing. We adopt an operational measure of an RF's longevity, namely, the number of measurements that can be made against it with a certain error tolerance. We investigate two distinct types of RF: a reference direction, realized by a spin-j system, and a phase reference, realized by an oscillator mode with bounded energy. For both cases, we show that our measure of longevity increases quadratically with the size of the reference system and is therefore non-additive. For instance, the number of measurements for which a directional RF consisting of N parallel spins can be put to use scales as N2. Our results quantify the extent to which microscopic or mesoscopic RFs may be used for repeated, high-precision measurements, without needing to be reset—a question that is important for some implementations of quantum computing. We illustrate our results using the proposed single-spin measurement scheme of magnetic resonance force microscopy.

Methods and apparatus for evaluating sensors and/or for controlling operation of an apparatus that includes a sensor

Abstract: A method for evaluating sensors includes receiving a first measurement signal from a first sensor configured to measure a parameter relating to a first apparatus, receiving a second measurement signal from a second sensor configured to measure the parameter as the parameter relates to a second apparatus, comparing the first measurement signal with the second measurement signal, and determining at least one of, whether the first measurement signal is inaccurate or the first sensor has failed based, at least in part, on the comparison between the first and second measurement signals.

Some penalisations of the Wiener measure

Abstract: A number of limit laws, which are obtained from various penalisations of the Wiener measure on C (ℝ+,ℝd), are shown to exist, and are described thoroughly, with the help of path decompositions

Can scanning tunnelling spectroscopy measure the density of states of semiconductor quantum dots

Abstract: Molecules, supramolecular structures and semiconductor nanocrystals are increasingly used as the active components in prototype opto-electrical devices with miniaturized dimensions and novel functions. Therefore, there is a strong need to measure the electronic structure of such single, individual nano-objects. Here, we explore the potential of scanning tunnelling spectroscopy to obtain quantitative information on the energy levels and Coulomb interactions of semiconductor quantum dots. We discuss the conditions under which shell-tunnelling, shell-filling and bipolar spectroscopy can be performed, and illustrate this with spectra acquired on individual CdSe and PbSe quantum dots. We conclude that quantitative information on the energy levels and Coulomb interactions can be obtained if the physics of the tip/quantum dot/substrate double-barrier tunnel junction is well understood.

A Simple, Robust Measure of Reverberation Echo Density

Abstract: A simple, robust method for measuring echo density from a reverberation impulse response is presented. Based on the property that a reverberant field takes on a Gaussian distribution once an acoustic space is fully mixed, the measure counts samples lying outside a standard deviation in a given impulse response window and normalizes by that expected for Gaussian noise. The measure is insensitive to equalization and reverberation time, and is seen to perform well on both artificial reverberation and measurements of room impulse responses. Listening tests indicate a correlation between echo density measured in this way and perceived temporal quality or texture of the reverberation.

Guest Editorial: Can We Actually Measure Health Disparities?

Abstract: F several decades, researchers around the world have studied demographic disparities in mortality. It is hard to know exactly how much money has been spent on this research. But certainly the amounts have run into the hundreds of million dollars. And, by and large, the conclusions of that research have been the same: The disparities have been increasing. But what if all that research was simply wrong, or, at best, confused to the point of offering negligible insight into the dynamics of group differences in experiencing adverse and favorable health outcomes? I explain below why this is pretty much the case and then address whether there is a better way to do it. The main problem with existing research lies in the failure to recognize the following statistical tendency, which we’ll call heuristic rule X (HRX): When two groups differ in their susceptibility to an outcome, the rarer the outcome, the greater the disparity in experiencing the outcome and the smaller the disparity in avoiding the outcome. Readily available income data illustrate HRX. The U.S. Census Bureau provides data on the number and proportion of each race falling below various percentages of the poverty line. Table 1 presents key elements of that data for blacks and whites in 2004, along with a number of fields expressing statistical relationships stemming from those elements. The information in Table 1 underlies the figures that follow and many of the points in the text. It should be recognized, however, that the essential aspects of the relationships reflected in the table and described below would be found in any set of data reflecting more or less normal distributions of factors associated with whether one experiences or avoids some outcome. Figure 1, which shows the proportions of blacks and whites falling below each of the percentages of the poverty line, provides what may be the best visual illustration of crucial aspects of the data. Consider what these data show for blacks and whites with respect to poverty. Blacks are more likely to be poor than whites, and, as is generally the case when one group is more susceptible to an outcome than another, blacks comprise a larger proportion of each segment of the combined black and white population that is increasingly susceptible to poverty. Correspondingly, the ratio of the black rate to the white rate of falling below each income level increases as the income level declines. For example, the black rate of falling below the poverty line (24.7%) is 2.3 times the white rate (10.8 %). But the black rate of the rarer event of falling below 50% of the poverty line (11.7%) is 2.7 times the GuEST EDITORIAL

System and method for measuring scene reflectance using optical sensors

Abstract: A system measures reflectance in a scene. A first optical sensor is configured to measure incident energy at a location in a scene. A second optical sensor is configured to measure reflected energy from the location in the scene. The incident energy and the reflected energy are analyzed to determine a photometric property at the location of the scene.

Global measure for assessing image fusion methods

Abstract: The objective evaluation of the performance of pixel level fusion methods is addressed. For this purpose a global measure based on information theory is proposed. The measure employs mutual and conditional mutual information to assess and represent the amount of information transferred from the source images to the final fused gray-scale image. Accordingly, the common information contained in the source images is considered only once in the performance evaluation procedure. The experimental results clarify the applicability of the proposed measure in comparing different fusion methods or in optimizing the parameters of a specific algorithm.

Moment-Height Tip-Over Measure for Stability Analysis of Mobile Robotic Systems

Abstract: Mobile machines equipped with manipulator arm(s) are being increasingly used in a variety of areas of industry. When these mobile utilities perform fast maneuvers, move over rough terrain, manipulate heavy work pieces, or interact large wrenches with their environment, they may go unstable and overturn. Therefore, safety and efficiency of such systems can be improved with a reliable stability recognition metric. For on-line applications, such tip-over stability measure should be computationally simple which makes its presentation a challenging task. In this study, various dynamic stability measures are investigated and compared with each other in terms of their reliability and computational complexity. Then, a new reliable and efficient metric named as Moment-Height Stability (MHS) measure is introduced for mobile manipulators. The proposed metric is a physically meaningful and reliable measure while it contains low computational burden. The MHS measure can be exploited successfully for wheeled mobile manipulators containing single or multiple arms. Besides, by some minor modifications the MHS measure can be also employed for the case of legged locomotion. Also, the proposed MHS measure may be extended for the case of suspended mobile manipulator on rough terrains. Several case studies are presented to reveal the effectiveness of the new MHS measure compared to the main previous measures.

Stability Evaluation of Mobile Robotic Systems using Moment-Height Measure

Abstract: Due to excessive maneuverability, mobile manipulators which consist of one or more manipulators mounted on a mobile base have attracted much of interest. Tipping-over is one of the most important problems in such systems especially when manipulating heavy objects, also during maneuvers in unknown environment or in rugged terrains. Therefore, estimation and evaluation of dynamic stability with appropriate easy-computed measure throughout the motion of such systems is a challenging task. In this study, various dynamic stability measures are investigated and compared with each other. Next, a new effective measure named as Moment-Height Stability (MHS) measure is presented for wheeled mobile manipulators. The proposed metric is physically meaningful based on principal concepts, and can be implemented with limited low computational effort. The suggested MHS measure can be effectively used for both legged robots and mobile manipulators. Finally, a few case studies are presented to compare the new MHS measure with the main existing measures. The obtained simulation results show the merits of the new proposed MHS measure, in terms of prediction the exact time of instability occurrence, without additional precautions of the other measures which may confine the maneuverability of the system and its operation.

Laser-driven shock waves for the study of extreme matter states

Abstract: During the last ten years, the ability of high power lasers to generate high energy density shocks has made them a reliable tool to study extreme states of matter. These states of matter are relevant in many important physics areas such as astrophysics, planetology and ICF physics. Here, we present some representative studies performed by using a driven laser shock: melting of iron at pressures relevant for geophysics, developments of new techniques to measure the density of highly compressed matter and a study of a radiative shock.

Method to Improve Downhole Instruments

Abstract: Measurements are made using a plurality of measure electrodes on a pad of a logging tool. The bias and gain of the measurements prior to A/D conversion are altered using measurements made by an additional electrode that is ahead of the measure electrodes.