2,437 research outputs found

    How to treat benchmark revisions? The case of German production and orders statistics

    Get PDF
    Elements of an econometric examination of benchmark revisions in real-time data are suggested. Structural break tests may be applied to detect heterogeneities within vintages. Systems cointegration tests are helpful to reveal inconsistencies across vintages. Differencing and rebasing, often used to adjust for benchmark revisions, are generally not sufficient to ensure consistent real-time macroeconomic data. Vintage transformation functions estimated by cointegrating regressions are more flexible. Inappropriate conversion may cause observed revision statistics to be affected by nuisance parameters. In German industrial production and orders statistics, remaining revisions are generally biased and serially correlated. --real-time data,benchmark revisions,industrial production,orders

    Thinking Ahead: Protecting the Environment in the 21st Century

    Get PDF
    The United States has made notable progress in cleaning up the environment over the last 30 years. Our nation\u27s air, land and water are, in almost all cases, significantly cleaner than they were only a few decades ago.\u27 Before declaring victory though, we must acknowledge that some environmental problems are getting worse, and the nature of our environmental problems has changed. Many environmental problems are now global problems, as opposed to problems that could be dealt with at the national or state level. Problems have become diffuse, with no clearly identifiable source and with a lengthy delay between cause and effect, whereas before problems were immediately obvious with distinct sources. Finally, environmental problems have become very complex, changing from the relatively simple problems such as thinning eggshells due to pesticide abuse . Government agencies continue to address this new generation of problems with tools designed for a generation of problems now largely behind us. The time has come to develop complementary tools designed for these new problems. As environmental regulatory agencies investigate new approaches to environmental protection, the way questions are phrased has a profound impact on the answers generated. If the question concerns how an environmental agency can do a better job working with businesses to ensure that they act in an environmentally responsible manner, then the nswer must involve some type of cooperative effort between the environmental agency and the relevant businesses. If, however, the question concerns how an environmental agency can best use its resources to protect the environment, then the answer may require the agency to work with many different groups. It is my belief that environmental regulatory agencies should be asking the second question. Further, one possible answer to the question of how to develop effective, supplemental approaches to protecting and enhancing the environment lies in educating and influencing the public, specifically with respect to consumer purchasing decisions

    Thinking Ahead: Protecting the Environment in the 21st Century

    Get PDF
    The United States has made notable progress in cleaning up the environment over the last 30 years. Our nation\u27s air, land and water are, in almost all cases, significantly cleaner than they were only a few decades ago.\u27 Before declaring victory though, we must acknowledge that some environmental problems are getting worse, and the nature of our environmental problems has changed. Many environmental problems are now global problems, as opposed to problems that could be dealt with at the national or state level. Problems have become diffuse, with no clearly identifiable source and with a lengthy delay between cause and effect, whereas before problems were immediately obvious with distinct sources. Finally, environmental problems have become very complex, changing from the relatively simple problems such as thinning eggshells due to pesticide abuse . Government agencies continue to address this new generation of problems with tools designed for a generation of problems now largely behind us. The time has come to develop complementary tools designed for these new problems. As environmental regulatory agencies investigate new approaches to environmental protection, the way questions are phrased has a profound impact on the answers generated. If the question concerns how an environmental agency can do a better job working with businesses to ensure that they act in an environmentally responsible manner, then the nswer must involve some type of cooperative effort between the environmental agency and the relevant businesses. If, however, the question concerns how an environmental agency can best use its resources to protect the environment, then the answer may require the agency to work with many different groups. It is my belief that environmental regulatory agencies should be asking the second question. Further, one possible answer to the question of how to develop effective, supplemental approaches to protecting and enhancing the environment lies in educating and influencing the public, specifically with respect to consumer purchasing decisions

    Complexity and Unwinding for Intransitive Noninterference

    Full text link
    The paper considers several definitions of information flow security for intransitive policies from the point of view of the complexity of verifying whether a finite-state system is secure. The results are as follows. Checking (i) P-security (Goguen and Meseguer), (ii) IP-security (Haigh and Young), and (iii) TA-security (van der Meyden) are all in PTIME, while checking TO-security (van der Meyden) is undecidable, as is checking ITO-security (van der Meyden). The most important ingredients in the proofs of the PTIME upper bounds are new characterizations of the respective security notions, which also lead to new unwinding proof techniques that are shown to be sound and complete for these notions of security, and enable the algorithms to return simple counter-examples demonstrating insecurity. Our results for IP-security improve a previous doubly exponential bound of Hadj-Alouane et al

    Telangiopsis Gen. Nov., an Upper Mississippian Pollen Organ from Arkansas

    Get PDF
    This is the publisher's version, also available electronically from www.jstor.org.Telangiopsis arkansanum is described from compressed synangiate pollen organs borne terminally on a monopodially branched system of slender axes. The specimens occur in a fine-grained shale unit of the Wedington sandstone (Chester series). Individual synangia contain five or six sporangia, measure approximately 1.0 mm long and 0.8 mm wide, and contain radial trilete spores ranging from 47 to 54 n in diameter. A discussion of the genus Telangium, to which similar remains would have previously been assigned, is presented. The generic name Telangium is retained for the petrified species T. scotti and T. pygmaeum, while the generic name Telangiopsis is proposed to include nonpetrifaction specimens previously assigned to the genus

    Saccade amplitude disconjugacy induced by aniseikonia: role of monocular depth cues

    Get PDF
    AbstractThe conjugacy of saccades is rapidly modified if the images are made unequal for the two eyes. Disconjugacy persists even in the absence of disparity which indicates learning. Binocular visual disparity is a major cue to depth and is believed to drive the disconjugacy of saccades to aniseikonic images. The goal of the present study was to test whether monocular depth cues can also influence the disconjugacy of saccades. Three experiments were performed in which subjects were exposed for 15–20 min to a 10% image size inequality. Three different images were used: a grid that contained a single monocular depth cue strongly indicating a frontoparallel plane; a random-dot pattern that contained a less prominent monocular depth cue (absence of texture gradient) which also indicates the frontoparallel plane; and a complex image with several overlapping geometric forms that contained a variety of monocular depth cues. Saccades became disconjugate in all three experiments. The disconjugacy was larger and more persistent for the experiment using the random-dot pattern that had the least prominent monocular depth cues. The complex image which had a large variety of monocular depth cues produced the most variable and less persistent disconjugacy. We conclude that the monocular depth cues modulate the disconjugacy of saccades stimulated by the disparity of aniseikonic images

    Modeling Inter-trial Variability of Saccade Trajectories: Effects of Lesions of the Oculomotor Part of the Fastigial Nucleus

    Get PDF
    This study investigates the inter-trial variability of saccade trajectories observed in five rhesus macaques (Macaca mulatta). For each time point during a saccade, the inter-trial variance of eye position and its covariance with eye end position were evaluated. Data were modeled by a superposition of three noise components due to 1) planning noise, 2) signal-dependent motor noise, and 3) signal-dependent premotor noise entering within an internal feedback loop. Both planning noise and signal-dependent motor noise (together called accumulating noise) predict a simple S-shaped variance increase during saccades, which was not sufficient to explain the data. Adding noise within an internal feedback loop enabled the model to mimic variance/covariance structure in each monkey, and to estimate the noise amplitudes and the feedback gain. Feedback noise had little effect on end point noise, which was dominated by accumulating noise. This analysis was further extended to saccades executed during inactivation of the caudal fastigial nucleus (cFN) on one side of the cerebellum. Saccades ipsiversive to an inactivated cFN showed more end point variance than did normal saccades. During cFN inactivation, eye position during saccades was statistically more strongly coupled to eye position at saccade end. The proposed model could fit the variance/covariance structure of ipsiversive and contraversive saccades. Inactivation effects on saccade noise are explained by a decrease of the feedback gain and an increase of planning and/or signal-dependent motor noise. The decrease of the fitted feedback gain is consistent with previous studies suggesting a role for the cerebellum in an internal feedback mechanism. Increased end point variance did not result from impaired feedback but from the increase of accumulating noise. The effects of cFN inactivation on saccade noise indicate that the effects of cFN inactivation cannot be explained entirely with the cFN's direct connections to the saccade-related premotor centers in the brainstem

    Magnetic suppression of perceptual accuracy is not reduced in episodic migraine without aura

    Get PDF
    Background: Altered cortical excitability is thought to be part of migraine pathophysiology. Reduced magnetic suppression of perceptual accuracy (MSPA) has been found in episodic migraine with aura and in chronic migraine, and has been interpreted as reduced inhibition of the occipital cortex in these migraine subtypes. Results are less clear for episodic migraine without aura. In the present study we compared MSPA between 24 healthy controls and 22 interictally measured episodic migraine patients without aura. In addition, we investigated test-retest reliability in 33 subjects (24 controls, 9 migraine). Findings: Visual accuracy was assessed by letter recognition and modulated by transcranial magnetic stimulation delivered to the occipital cortex at different intervals to the letter presentation (40, 100 and 190 ms). The results confirm suppression of visual accuracy at the 100 ms interval (p < 0.001), but there were no significant group differences (percentage of correctly recognized letters, control: 36.1 +/- 36.2; migraine: 44.0 +/- 32.3, p = 0.44). Controls and migraine patients were pooled for assessment of test-retest reliability (n = 33). Levels of suppression at 100 ms were similar at test (percentage of correctly recognized letters: 42.3 +/- 32.6) and retest (41.9 +/- 33.8, p = 0.90) and test-retest correlations were good (r = 0.82, p < 0.001). Conclusions: The results demonstrate that occipital cortex inhibition as assessed with MSPA is not reduced in episodic migraine without aura. This suggests a larger role of occipital cortex excitability in episodic migraine with aura and in chronic migraine compared to episodic migraine without aura. Test-retest reliability of MSPA was good

    Transforming 2D Radar Remote Sensor Information from a UAV into a 3D World-View

    Get PDF
    [EN] Since unmanned aerial vehicles (UAVs) have been established in geoscience as a key and accessible tool, a wide range of applications are currently being developed. However, not only the design of UAVs themselves is vital to carry out an accurate investigation, but also the sensors and the data processing are key parts to be considered. Several publications including accurate sensors are taking part in pioneer research programs, but less is explained about how they were designed. Besides the commonly used sensors such as a camera, one of the most popular ones is radar. The advantages of a radar sensor to perform research in geosciences are the robustness, the ability to consider large distances and velocity measurements. Unfortunately, these sensors are often expensive and there is a lack of methodological papers that explain how to reduce these costs. To fill this gap, this article aims to show how: (i) we used a radar sensor from the automotive field; and (ii) it is possible to reconstruct a three-dimensional scenario with a UAV and a radar sensor. Our methodological approach proposes a total of eleven stages to process the radar data. To verify and validate the process, a real-world scenario reconstruction is presented with a system resolution reaching from two to three times the radar resolution. We conclude that this research will help the scientific community to include the use of radars in their research projects and programs, reducing costs and increasing accuracy.This research work was supported by the "European Regional Development Fund" (EFRE) in the context of the aim of "Investment in Growth and Employment" (IWB) in Rhineland-Palatinate, Germany.Weber, C.; Eggert, M.; Rodrigo-Comino, J.; Udelhoven, T. (2022). Transforming 2D Radar Remote Sensor Information from a UAV into a 3D World-View. Remote Sensing. 14(7). https://doi.org/10.3390/rs1407163314

    06441 Abstracts Collection -- Naming and Addressing for Next Generation Internetworks

    Get PDF
    From 29.10.06 to 01.11.06, the Dagstuhl Seminar 06441``Naming and Addressing for Next-Generation Internetworks\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available
    • …
    corecore