Estimation of the control parameter from symbolic sequences: Unimodal maps with variable critical point

The work described in this paper can be interpreted as an application of the order patterns of symbolic dynamics when dealing with unimodal maps. Specifically, it is shown how Gray codes can be used to estimate the probability distribution functions (PDFs) of the order patterns of parametric unimodal maps. Furthermore, these PDFs depend on the value of the parameter, what eventually provides a handle to estimate the parameter value from symbolic sequences (in form of Gray codes), even when the critical point depends on the parameter.Comment: 10 pages, 14 figure

On orthogonal generalized equitable rectangles

In this note, we give a complete solution of the existence of orthogonal generalized equitable rectangles, which was raised as an open problem in [4]. Key words: orthogonal latin squares, orthogonal equitable rectangles,

Orthogonal Arrays of Strength Three from Regular 3-Wise Balanced Designs

The construction given in Kreher, J Combin Des 4 (1996) 67 is extended to obtain new infinite families of orthogonal arrays of strength 3. Regular 3-wise balanced designs play a central role in this construction

Do cause and effect need to be temporally continuous? Learning to compensate for delayed vestibular feedback

Delaying the presentation of information to one modality relative to another (an intersensory temporal offset) impairs performance on a wide range of tasks. We have recently shown, however, that a few minutes exposure to delayed visual feedback induces sensorimotor temporal adaptation, returning performance to normal. Here, we examine whether adaptation to delayed vestibular feedback is possible. Subjects were placed on a motion platform, and were asked to perform a stabilization task. The task was similar to balancing a rod on the tip of your finger. Specifically, the platform acted as if it were on the end of an inverted pendulum, with subjects applying an acceleration to the platform via a joystick. The more difficulty one has in stabilizing the platform the more it will oscillate, increasing the variability in the platform's position. The experiment was divided into 3 sections. During the Baseline section (5 minutes), subjects performed the task with immediate vestibular feedback. They then were presented with a Training section, consisting of 4 sessions (5 minutes each) during which vestibular feedback was delayed by 500 ms. Finally, subjects were presented with a Post-test (two minutes) with no feedback delay. Subjects performed rather well in the Baseline section (average standard deviation of platform tilt was 1.37 degrees). The introduction of the delay greatly impaired performance (8.81 degrees standard deviation in the 1st Training session), but performance rapidly showed significant improvement (5.59 degrees standard deviation during the last training section, p<0.04). Subjects clearly learned to compensate, at least partially, for the delayed vestibular feedback. Performance during the Post-test was worse than during Baseline (2.48 degrees standard deviation in tilt). This decrease suggests that the improvement seen during training might be the result of intersensory temporal adaptation

Ozone-depleting substances (ODSs) and related chemicals

The amended and adjusted Montreal Protocol continues to be successful at reducing emissions and atmospheric abundances of most controlled ozone-depleting substances (ODSs).Global Ozone Research and Monitoring Projec

Interferon-stimulated gene (ISG)-expression screening reveals the specific antibunyaviral activity of ISG20

Bunyaviruses pose a significant threat to human health, prosperity and food security. In response to viral infections, interferons (IFNs) upregulate the expression of hundreds of interferon stimulated genes (ISGs) whose cumulative action can potently inhibit the replication of bunyaviruses. We used a flow cytometry-based method to screen the ability of ∼500 unique ISGs from humans and rhesus macaques to inhibit the replication of Bunyamwera orthobunyavirus (BUNV), the prototype of both the Peribunyaviridae family and Bunyavirales order. Candidates possessing antibunyaviral activity were further examined using a panel of divergent bunyaviruses. Interestingly, one candidate, ISG20, exhibited potent antibunyaviral activity against most viruses examined from the Peribunyaviridae, Hantaviridae and Nairoviridae families, whereas phleboviruses (Phenuiviridae) largely escaped inhibition. Similar to other viruses known to be targeted by ISG20, the antibunyaviral activity of ISG20 is dependent upon its functional ribonuclease activity. Through use of an infectious VLP assay (based on the BUNV minigenome system), we confirmed that gene expression from all 3 viral segments is strongly inhibited by ISG20. Using in vitro evolution, we generated a substantially ISG20-resistant BUNV and mapped the determinants of ISG20 sensitivity/resistance. Taken together, we report that ISG20 is a broad and potent antibunyaviral factor yet some bunyaviruses are remarkably ISG20 resistant. Thus, ISG20 sensitivity/resistance could influence the pathogenesis of bunyaviruses, many of which are emerging viruses of clinical or veterinary significance

A new interpretation of total column BrO during Arctic spring

Emission of bromine from sea-salt aerosol, frost flowers, ice leads, and snow results in the nearly complete removal of surface ozone during Arctic spring. Regions of enhanced total column BrO observed by satellites have traditionally been associated with these emissions. However, airborne measurements of BrO and O3 within the convective boundary layer (CBL) during the ARCTAS and ARCPAC field campaigns at times bear little relation to enhanced column BrO. We show that the locations of numerous satellite BrO "hotspots" during Arctic spring are consistent with observations of total column ozone and tropopause height, suggesting a stratospheric origin to these regions of elevated BrO. Tropospheric enhancements of BrO large enough to affect the column abundance are also observed, with important contributions originating from above the CBL. Closure of the budget for total column BrO, albeit with significant uncertainty, is achieved by summing observed tropospheric partial columns with calculated stratospheric partial columns provided that natural, short-lived biogenic bromocarbons supply between 5 and 10 ppt of bromine to the Arctic lowermost stratosphere. Proper understanding of bromine and its effects on atmospheric composition requires accurate treatment of geographic variations in column BrO originating from both the stratosphere and troposphere. Copyright 2010 by the American Geophysical Union

A new interpretation of total column BrO during Arctic spring

Emission of bromine from sea-salt aerosol, frost flowers, ice leads, and snow results in the nearly complete removal of surface ozone during Arctic spring. Regions of enhanced total column BrO observed by satellites have traditionally been associated with these emissions. However, airborne measurements of BrO and O3 within the convective boundary layer (CBL) during the ARCTAS and ARCPAC field campaigns at times bear little relation to enhanced column BrO. We show that the locations of numerous satellite BrO “hotspots” during Arctic spring are consistent with observations of total column ozone and tropopause height, suggesting a stratospheric origin to these regions of elevated BrO. Tropospheric enhancements of BrO large enough to affect the column abundance are also observed, with important contributions originating from above the CBL. Closure of the budget for total column BrO, albeit with significant uncertainty, is achieved by summing observed tropospheric partial columns with calculated stratospheric partial columns provided that natural, short-lived biogenic bromocarbons supply between 5 and 10 ppt of bromine to the Arctic lowermost stratosphere. Proper understanding of bromine and its effects on atmospheric composition requires accurate treatment of geographic variations in column BrO originating from both the stratosphere and troposphere

Connecting and merging fibres: Pathway extraction by combining probability maps

Probability mapping of connectivity is a powerful tool to determine the fibre structure of white matter in the brain. Probability maps are related to the degree of connectivity to a chosen seed area. In many applications, however, it is necessary to isolate a fibre bundle that connects two areas. A frequently suggested solution is to select curves, which pass only through two or more areas. This is very inefficient, especially for long-distance pathways and small areas. In this paper, a novel probability-based method is presented that is capable of extracting neuronal pathways defined by two seed points. A Monte Carlo simulation based tracking method, similar to the Probabilistic Index of Connectivity (PICo) approach, was extended to preserve the directional information of the main fibre bundles passing a voxel. By combining two of these extended visiting maps arising from different seed points, two independent parameters are determined for each voxel: the first quantifies the uncertainty that a voxel is connected to both seed points; the second represents the directional information and estimates the proportion of fibres running in the direction of the other seed point (connecting fibre) or face a third area (merging fibre). Both parameters are used to calculate the probability that a voxel is part of the bundle connecting both seed points. The performance and limitations of this DTI-based method are demonstrated using simulations as well as in vivo measurements. © 2008 Elsevier Inc. All rights reserved

Effective problem solving using SAT solvers

In this article we demonstrate how to solve a variety of problems and puzzles using the built-in SAT solver of the computer algebra system Maple. Once the problems have been encoded into Boolean logic, solutions can be found (or shown to not exist) automatically, without the need to implement any search algorithm. In particular, we describe how to solve the $n$-queens problem, how to generate and solve Sudoku puzzles, how to solve logic puzzles like the Einstein riddle, how to solve the 15-puzzle, how to solve the maximum clique problem, and finding Graeco-Latin squares.Comment: To appear in Proceedings of the Maple Conference 201