84,857 research outputs found
Soft behavior of string amplitudes with external massive states
We briefly discuss the soft behavior of scattering amplitudes both in string
and quantum field theory. In particular we show a general argument about the
validity of soft theorems for open superstring amplitudes and list some of our
recent results.Comment: 2 pages, poster presented at IFAE 201
Environmental boundary tracking and estimation using multiple autonomous vehicles
In this paper, we develop a framework for environmental
boundary tracking and estimation by considering the
boundary as a hidden Markov model (HMM) with separated
observations collected from multiple sensing vehicles. For each
vehicle, a tracking algorithm is developed based on Page’s
cumulative sum algorithm (CUSUM), a method for change-point
detection, so that individual vehicles can autonomously
track the boundary in a density field with measurement noise.
Based on the data collected from sensing vehicles and prior
knowledge of the dynamic model of boundary evolvement, we
estimate the boundary by solving an optimization problem, in
which prediction and current observation are considered in the
cost function. Examples and simulation results are presented
to verify the efficiency of this approach
Evaluating Methods of Correcting for Multiple Comparisons Implemented in SPM12 in Social Neuroscience fMRI Studies: An Example from Moral Psychology
In fMRI research, the goal of correcting for multiple comparisons is to identify areas of activity that reflect true effects, and thus would be expected to replicate in future studies. Finding an appropriate balance between trying to minimize false positives (Type I error) while not being too stringent and omitting true effects (Type II error) can be challenging. Furthermore, the advantages and disadvantages of these types of errors may differ for different areas of study. In many areas of social neuroscience that involve complex processes and considerable individual differences, such as the study of moral judgment, effects are typically smaller and statistical power weaker, leading to the suggestion that less stringent corrections that allow for more sensitivity may be beneficial, but also result in more false positives. Using moral judgment fMRI data, we evaluated four commonly used methods for multiple comparison correction implemented in SPM12 by examining which method produced the most precise overlap with results from a meta-analysis of relevant studies and with results from nonparametric permutation analyses. We found that voxel-wise thresholding with family-wise error correction based on Random Field Theory provides a more precise overlap (i.e., without omitting too few regions or encompassing too many additional regions) than either clusterwise thresholding, Bonferroni correction, or false discovery rate correction methods
Wood Ducks as Accidental Hosts of the Squirrel Flea, \u3ci\u3eOrchopeas Howardi\u3c/i\u3e (Siphonaptera: Ceratophyllidae)
(excerpt)
On 21 May 1985, two recently hatched wood ducklings, Aix sponsa (L.), brought to the McHenry County Wildlife Rehabilitation Center, Woodstock, Illinois, were inspected for ectoparasites
Simple Technique for source reflection coefficient measurement while characterizing active devices
This paper describes a simple, yet rigorous technique for fast and accurate determination of the source reflection coefficient during the characterization of microwave active devices. The solution consists in measuring the waves at the DUT reference plane under two different bias conditions. Since the DUT small signal impedance value depends on the bias voltage, the waves at the DUT input port changes as well. We proved that their measurements give enough information to compute the source reflection coefficient with accuracy suitable for most applications. The correction for systematic errors is based in the traditional error-box model and it does not require any exotic calibration procedures. Experimental results are presented and compared to data obtained with more traditional technique
Predicing Ecological Effects of Watershed-Wide Rain Garden Implementation Using a Low-Cost Methodology
Stormwater control measures (SCMs) have been employed to mitigate peak flows and pollutants ssociated with watershed urbanization. Downstream ecological effects caused by the implementation of SCMs are largely unknown, especially at the watershed scale. Knowledge of these effects could help with setting goals for and targeting locations of local restoration efforts. Unfortunately, studies such as these typically require a high level of time and effort for the investigating party, of which resources are often limited. This study proposes a low-cost investigation method for the prediction of ecological effects on the watershed scale with the implementation of rain garden systems by using publicly available data and software. For demonstration purposes, a typical urban watershed was modeled using Storm Water Management Model (SWMM) 5.0. Forty-five models were developed in which the percent impervious area was varied 3 to 80%, and the fraction of rain gardens implemented with respect to the number of structures was varied from to 100%. The river chub fish (Nocomis micropogon) and its congeners (Nocomis spp.) were chosen as ecological indicators, as they are considered to be keystone species through interspecific nesting association. Depth and velocity criteria for successful nest building locations of the river chub were determined; these criteria can then be applied to many other watersheds. In this study, both base flow conditions and a typical summer storm event (1.3 cm, 6 h duration) were evaluated. During the simulated storm, nest-building locations were not affected in the 3 and 5% impervious cover models. Nest destruction was found to occur in approximately 54% of the original nest building sites for the 9% and 10% impervious areas. Nearly all of the nest-building locations were uninhabitable for impervious areas 20% and greater. Rain garden implementation significantly improved river chub habitat in the simulation, with greatest marginal benefit at lower levels of implementation
The Human Right to Science and Foundational Technologies
Feeney et al. (2018) make a valid argument for restrictions on the exclusivity of foundational technologies such as CRISPR. The issue of balancing intellectual property right with access to scientific and technological advancements is certainly not new. In our commentary, we argue that the human right to science offers a more concrete basis for governments to balance their competing commitments in promoting scientific development on the one hand, and ensuring benefit-sharing on the other, in ways that advance social justice under non-ideal conditions
Efficient multitasking of Choleski matrix factorization on CRAY supercomputers
A Choleski method is described and used to solve linear systems of equations that arise in large scale structural analysis. The method uses a novel variable-band storage scheme and is structured to exploit fast local memory caches while minimizing data access delays between main memory and vector registers. Several parallel implementations of this method are described for the CRAY-2 and CRAY Y-MP computers demonstrating the use of microtasking and autotasking directives. A portable parallel language, FORCE, is used for comparison with the microtasked and autotasked implementations. Results are presented comparing the matrix factorization times for three representative structural analysis problems from runs made in both dedicated and multi-user modes on both computers. CPU and wall clock timings are given for the parallel implementations and are compared to single processor timings of the same algorithm
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