An Effect of Relative Motion on Trajectory Discrimination

Psychophysical studies point to the existence of specialized mechanisms sensitive to the relative motion between an object and its background. Such mechanisms would seem ideal for the motion-based segmentation of objects; however, their properties and role in processing the visual scene remain unclear. Here we examine the contribution of relative motion mechanisms to the processing of object trajectory. In a series of four psychophysical experiments we examine systematically the effects of relative direction and speed differences on the perceived trajectory of an object against a moving background. We show that background motion systematically influences the discrimination of object direction. Subjects’ ability to discriminate direction was consistently better for objects moving opposite a translating background than for objects moving in the same direction as the background. This effect was limited to the case of a translating background and did not affect perceived trajectory for more complex background motions associated with self-motion. We interpret these differences as providing support for the role of relative motion mechanisms in the segmentation and representation of object motions that do not occlude the path of an observer’s self-motion

Small Dollar Loans, Big Problems: How States Protect Consumers From Abuses and How the Federal Government Can Help

Across America, drivers pass twice as many payday loan storefronts as Starbucks coffee shops.2 In twenty-nine states, there are more payday lender stores than McDonald’s restaurants.3 Numerous research studies warn of the dangers associated with payday loans, including significantly higher rates of bankruptcies, evictions, utility shut-offs, and involuntary bank account closures.4 Many states have recognized the dangers posed by payday and other types of small-dollar loans with predatory features, prompting them to adopt laws to combat the abusive nature of these loans. These laws, however, offer consumers varying degrees of protection. Historically, states have used their police powers to protect consumers from predatory lending. This Article discusses the extent to which each state’s current laws protect consumers from lending abuses associated with four common small-dollar loans: payday loans, auto-title loans, six-month installment loans, and one-year installment loans.5 Specifically, this Article highlights the findings from the 2010 Small Dollar Loan Products Scorecard (Scorecard), which updated the original 2008 Scorecard. 6 Both the 2008 and 2010 Scorecard grade state laws based on the maximum annual percentage rate (APR) they allow for the four typical small-dollar loan products listed above. Since the 2008 Scorecard, there has been significant state legislative activity across the country related to small-dollar loans. Only a handful of states, however, have enacted new measures that adequately protect consumers. This Article provides policy recommendations to guide ongoing reform efforts. The Article highlights three key points. First, states should continue their longstanding good fight on behalf of American families against abusive, small dollar lending, but they need help. Congress and the Consumer Financial Protection Bureau (CFPB), which President Obama established when he signed the Dodd-Frank Wall Street Reform and Consumer Protection Act into law on July 21, 2010, should join the battle.7 Second, the states and Congress should focus their reform efforts on enacting an across-the-board usury cap of 36% APR on all small-dollar loans. Third, the states, CFPB, and Congress should impose several restrictions on high-cost (over 36% APR), small-dollar lending to help curb its abusive nature. In this Article, Part II describes the methodology used by the 2010 Scorecard. Part III reports the major changes that have occurred in the two years since the Scorecard’s original 2008 publication. Finally, Part IV proposes several policy recommendations, at the state and federal level, with the focus in the latter category on opportunities for action by the newly created CFPB

Majorana neutrino decay in an Effective Approach

The search strategy or the finding of new effects for heavy neutrinos often relies on their different decay channels to detectable particles. In particular in this work we study the decay of a Majorana neutrino with interactions obtained from an effective general theory modeling new physics at the scale $\Lambda$. The results obtained are general because they are based in an effective theory and not in specific models. We are interested in relatively light heavy Majorana neutrinos, with masses lower than the $W$ mass ($m_N<m_W$). This mass range simplifies the study by reducing the possible decay modes. Moreover, we found that for $\Lambda\sim 1$ T$e$V, the neutrino plus photon channel could give explanation to different observations: we analyze the potentiality of the studied interactions to explain some neutrino-related problems like the MiniBooNE and SHALON anomalies. We show in different figures the dominant branching ratios and the decay length of the Majorana neutrino in this approach. This kind of heavy neutral leptons could be searched for in the LHC with the use of displaced vertices techniques. \Comment: 15 page, 5 figure

Single-Scattering Optical Tomography

We consider the problem of optical tomographic imaging in the mesoscopic regime where the photon mean free path is of order of the system size. Within the accuracy of the single-scattering approximation to the radiative transport equation, we show that it is possible to recover the extinction coefficient of an inhomogeneous medium from angularly-resolved measurements. Applications to biomedical imaging are described and illustrated with numerical simulations.Comment: Finalized and submitted to PR

A Quantitative and Standardized Robotic Method for the Evaluation of Arm Proprioception After Stroke

Stroke often results in both motor and sensory deficits, which may interact in the manifested functional impairment. Proprioception is known to play important roles in the planning and control of limb posture and movement; however, the impact of proprioceptive deficits on motor function has been difficult to elucidate due in part to the qualitative nature of available clinical tests. We present a quantitative and standardized method for evaluating proprioception in tasks directly relevant to those used to assess motor function. Using a robotic manipulandum that exerted controlled displacements of the hand, stroke participants were evaluated, and compared with a control group, in their ability to detect such displacements in a 2-alternative, forced-choice paradigm. A psychometric function parameterized the decision process underlying the detection of the hand displacements. The shape of this function was determined by a signal detection threshold and by the variability of the response about this threshold. Our automatic procedure differentiates between participants with and without proprioceptive deficits and quantifies functional proprioceptive sensation on a magnitude scale that is meaningful for ongoing studies of degraded motor function in comparable horizontal movements

The emotional valence of subliminal priming effects perception of facial expressions

We investigated, in young healthy subjects, how the affective content of subliminally presented priming images and their specific visual attributes impacted conscious perception of facial expressions. The priming images were broadly categorised as aggressive, pleasant, or neutral and further subcategorised by the presence of a face and by the centricity (egocentric or allocentric vantage-point) of the image content. Subjects responded to the emotion portrayed in a pixelated target-face by indicating via key-press if the expression was angry or neutral. Priming images containing a face compared to those not containing a face significantly impaired performance on neutral or angry targetface evaluation. Recognition of angry target-face expressions was selectively impaired by pleasant prime images which contained a face. For egocentric primes, recognition of neutral target-face expressions was significantly better than of angry expressions. Our results suggest that, first, the affective primacy hypothesis which predicts that affective information can be accessed automatically, preceding conscious cognition, holds true in subliminal priming only when the priming image contains a face. Second, egocentric primes interfere with the perception of angry target-face expressions suggesting that this vantage-point, directly relevant to the viewer, perhaps engages processes involved in action preparation which may weaken the priority of affect processing.Accepted manuscrip