18,116 research outputs found
Preempting Unintended Consequences
Sommer offers some insights on preemption. The case for preemption is that there is an inherent logic and consistency in having litigation involving nationally traded securities resolved in a single forum
Why Joanna Baptista Sold Herself into Slavery: Indian Women in Portuguese Amazonia, 1755-1798
In 1780, in Belem, Brazil, Joanna Baptista sold herself into slavery. This article probes Joanna’s motives and situates her actions not only in the milieu of slaveholding Brazil, but also in the more specific context of Portuguese Amazonia during the Directorate (1758–1798). Indians, especially former slaves and their descendants, faced forced resettlement and increased labor demands. Joanna’s case and contemporary petitions demonstrate how women of Indian and mixed descent, especially single women, widows and orphans, used legal means to defend their autonomy
Frontal Eye Field Neurons Assess Visual Stability Across Saccades
The image on the retina may move because the eyes move, or because something in the visual scene moves. The brain is not fooled by this ambiguity. Even as we make saccades, we are able to detect whether visual objects remain stable or move. Here we test whether this ability to assess visual stability across saccades is present at the single-neuron level in the frontal eye field (FEF), an area that receives both visual input and information about imminent saccades. Our hypothesis was that neurons in the FEF report whether a visual stimulus remains stable or moves as a saccade is made. Monkeys made saccades in the presence of a visual stimulus outside of the receptive field. In some trials, the stimulus remained stable, but in other trials, it moved during the saccade. In every trial, the stimulus occupied the center of the receptive field after the saccade, thus evoking a reafferent visual response. We found that many FEF neurons signaled, in the strength and timing of their reafferent response, whether the stimulus had remained stable or moved. Reafferent responses were tuned for the amount of stimulus translation, and, in accordance with human psychophysics, tuning was better (more prevalent, stronger, and quicker) for stimuli that moved perpendicular, rather than parallel, to the saccade. Tuning was sometimes present as well for nonspatial transaccadic changes (in color, size, or both). Our results indicate that FEF neurons evaluate visual stability during saccades and may be general purpose detectors of transaccadic visual change
A stochastic large deformation model for computational anatomy
In the study of shapes of human organs using computational anatomy, variations are found to arise from inter-subject anatomical differences, disease-specific effects, and measurement noise. This paper introduces a stochastic model for incorporating random variations into the Large Deformation Diffeomorphic Metric Mapping (LDDMM) framework. By accounting for randomness in a particular setup which is crafted to fit the geometrical properties of LDDMM, we formulate the template estimation problem for landmarks with noise and give two methods for efficiently estimating the parameters of the noise fields from a prescribed data set. One method directly approximates the time evolution of the variance of each landmark by a finite set of differential equations, and the other is based on an Expectation-Maximisation algorithm. In the second method, the evaluation of the data likelihood is achieved without registering the landmarks, by applying bridge sampling using a stochastically perturbed version of the large deformation gradient flow algorithm. The method and the estimation algorithms are experimentally validated on synthetic examples and shape data of human corpora callosa
A critical examination of discrete lattice and dispersed barrier hardening
Critical assessment of discrete lattice and dispersed barrier hardening theories of thermally activated deformation of metal
Images for Iconoclasts: Images of Confucius in the Cultural Revolution
Confucius died and was buried in 479 B.C.E., and he was never seen again. Or so one would think. “You may forget me as I once was,” Confucius reminds us in the Zhuangzi, but there is something unforgettable about me that will still live on. Confucius’s physical frame was concealed from sight below ground, but his body and face were not forgotten either by his followers or his detractors, each of whom remembered him (or remembered him) in different ways. People created semblances of Confucius that reflected their own visions of the past, and constructions of his body took on many lives of their own over the succeeding centuries. [excerpt
An investigation of some effects of mach number and air temperature on the hypersonic flow over a blunt body
Mach number and air temperature effect on hypersonic flow over blunt bodie
- …