254 research outputs found
Haptic Communications
No full textSteinbach E, Hirche S, Ernst MO, et al. Haptic Communications. PROCEEDINGS OF THE IEEE, FRONTIERS OF AUDIOVISUAL COMMUNICATIONS. In Press;100(4):937-956.Audiovisual communications is at the core of multimedia
systems that allow users to interact across distances. It is
common understanding that both audio and video are required
for high quality interaction. While audiovisual information provides
a user with a satisfactory impression of being present in
a remote environment, physical interaction and manipulation
is not supported. True immersion into a distant environment
and efficient distributed collaboration require the ability to
physically interact with remote objects and to literally get in
touch with other people. Touching and manipulating objects
remotely becomes possible if we augment traditional audiovisual
communications by the haptic modality. Haptic communications
is a relatively young field of research that has the potential
to substantially improve Human-Human and Human-Machine-
Interaction. In this paper we discuss the state-of-the-art in haptic
communications both from a psychophysical and technical point
of view. From a human perception point of view, we mainly focus
on the multimodal integration of audio, video and haptics and
the improved performance that can be achieved when combining
them.We also discuss how the human adapts to discrepancies and
synchronization errors between different modalities, a research
area which is typically referred to as perceptual learning. From
a technical perspective, we address perceptual coding of haptic
information and the transmission of haptic data streams over
resource-constrained and potentially lossy networks in the presence
of unpredictable and time-varying communication delays.
In this context, we also discuss the need for objective quality
metrics for haptic communication. Throughout the paper we
stress the fact that haptic communications is not meant as
a replacement of traditional audiovisual communications but
rather as an additional dimension for telepresence that will allow
us to advance in our quest for truly immersive communication
An empirical assessment of the universality of ANNs to predict oscillatory time series
No full textArtificial neural networks (ANNs) are universal function approximators, therefore suitable to be trained as predictors of oscillatory time series. Though several ANN architectures have been tested to predict both synthetic and real-world time series, the universality of their predictive power remained unexplored. Here we empirically test this universality across five well-known chaotic oscillators, limiting the analysis to the simplest architecture, namely multi-layer feed-forward ANN trained to predict one sampling step ahead. To compare different predictors, data are sampled according to their frequency content and the ANN structure scales with the characteristic dimensions of the oscillator. Moreover, the quality of recursive multi-step-ahead predictions are compared in terms of the system’s (largest) Lyapunov exponent (LLE), i.e., the predictive power is measured in terms of the number of Lyapunov times (LT, the LLE inverse) predicted within a prescribed (relative) error. The results confirm the rather uniform predictive power of the proposed ANN architecture
Robot team teleoperation for cooperative manipulation using wearable haptics
No full textRobot teams require planning and adaptive capabilities in order to perform cooperative manipulation tasks in dynamic or unstructured environments. Since these capabilities are inherent to humans, it is suitable to consider human-robot team teleoperation for cooperative manipulation where a single human collaborates with the robot team. In this paper, we present a subtask-based control approach which enables a simultaneous execution of two subtasks by the robot team, interacting with the object: trajectory tracking and formation preservation. Control inputs for both subtasks are provided by the human operator. The commands are projected onto the spaces of subtasks using a command mapping strategy. Analogously, measured interacting forces are projected onto the space of feedback signals, provided to the human via wearable fingertip haptic devices through a feedback mapping strategy. Experimental results validate the proposed approach
Does egg production represent adult female copepod growth? A call to account for body weight changes
No full textAn almost universal assumption in determining growth in copepods is that, over short periods, an individual adult female's net growth is equal to the amount of material expelled as eggs. This assumption relies upon adult body mass being in steady-state between the start and end of the same period. We explore different situations where this assumption is violated. Initially, concepts of how adult body weight and egg output are coupled over time are addressed. Using a refined concept of growth, we show that using typical 24 h incubation methods to measure egg output in sac spawners or broadcasters that produce clutches of eggs with a periodicity of >1 d may give correct mean population growth rates, but erroneous individual rates (including maximum and minimum individual growth, and measurements of individual variability such as coefficient of variation). Measurements derived from laboratory and field studies are then used to explore errors associated with the steady-state assumption. Decoupling of egg production from assimilation, and non-steady-state body weight in large lipid-storing higher-latitude species are relatively well documented, yet growth estimates allowing for such changes have almost never been made. Errors are not limited only to such species, however, and changing adult body weights can occur in small temperate and tropical species too. Body weight can increase or decrease whether or not eggs are exuded over the same period. The errors that can arise if we assume that the output of eggs by females equals their net growth rate are large and variable; in our compilation they range from -208% (i.e. egg output being 9.7% of body carbon weight per day, but adult carbon weight simultaneously declining by 13.7% d-1) to +71% (i.e. egg output being 1.5% of body carbon weight per day, and adult carbon weight simultaneously increasing by 4.3% d-1). Using measurement of the natural variability in adult body weights, we determined that in order to be able to discriminate significant changes in body weight of 1 and 10% respectively, >1000 and <100 replicates are necessary, if applying typical sacrificial weighing methods. If we are to make accurate estimates of growth in adult copepods, then changes in body weight are of fundamental importance. We make initial recommendations for tackling these problems and reducing errors in the future.</p
Response to methimazole in Graves' disease. The European Multicenter Study Group.
No full textOBJECTIVE:
A variety of regimens continue to be used in the treatment of Graves' disease with antithyroid drugs. We have investigated the factors which determine the initial response to methimazole (time until euthyroidism is achieved) in Graves' disease.
PATIENTS:
Five hundred and nine patients with Graves' disease in different European countries with normal and subnormal iodine supply. Patients were randomized to treatment with either 10 or 40 mg of methimazole per day for one year, with levothyroxine supplementation as required to maintain euthyroidism. Investigations were carried out before treatment and at 3 and 6 weeks and 3, 6, 9 and 12 months.
MEASUREMENTS:
Response was assessed by serial measurements of serum thyroid hormones. TSH receptor antibodies, thyroid autoantibodies and urinary iodide excretion were measured centrally. Twenty-minute thyroid uptake was measured by standard techniques. Data were collected and analysed centrally. Standard techniques as well as a stepwise logistic regression model were used to examine the relations between methimazole dose, age, goitre size, presence of endocrine eye signs, thyroid hormone levels, urinary iodide excretion, thyroid uptake, index of disease severity (Crooks), presence of TSH receptor antibodies and duration of the hyperthyroid phase.
RESULTS:
Within 3 weeks, 40.2% of patients responded to 10 mg of methimazole and 77.5% responded within 6 weeks. The corresponding figures for 40 mg of methimazole were 64.6 and 92.6%. Significant associations were found between duration of hyperthyroidism and the following variables: goitre size, urinary iodide excretion, methimazole dose, presence of TSH receptor antibodies (TBIAb), index of disease severity (Crooks) and pretreatment thyroid hormone levels. Response to methimazole was delayed in patients with large goitres, iodine excretion of > or = 100 micrograms/g creatinine, high pretreatment thyroid hormone levels, elevated levels of TBIAb and treatment with only 10 mg of methimazole. In the 10-mg group, 46% of patients were euthyroid within 3 weeks when urinary iodide was < 50 microgram/g of creatinine, and only 27% when iodide was above 100 micrograms/g. By stepwise logistic regression, the main factors for the response to methimazole were daily dose, pretreatment T3 levels, and goitre size.
CONCLUSION:
Methimazole dose, pretreatment serum T3 levels, and goitre size are the main determinants of the therapeutic response to methimazole in Graves' disease, at least in areas comprising low, subnormal and normal iodine supply
Distributed submodular minimization via block-wise updates and communications
No full textIn this paper we deal with a network of computing agents with local processing and neighboring communication capabilities that aim at solving (without any central unit) a submodular optimization problem. The cost function is the sum of many local submodular functions and each agent in the network has access to one function in the sum only. In this distributed set-up, in order to preserve their own privacy, agents communicate with neighbors but do not share their local cost functions. We propose a distributed algorithm in which agents resort to the Lovàsz extension of their local submodular functions and perform local updates and communications in terms of single blocks of the entire optimization variable. Updates are performed by means of a greedy algorithm which is run only until the selected block is computed, thus resulting in a reduced computational burden. The proposed algorithm is shown to converge in expected value to the optimal cost of the problem, and an approximate solution to the submodular problem is retrieved by a thresholding operation. As an application, we consider a distributed image segmentation problem in which each agent has access only to a portion of the entire image. While agents cannot segment the entire image on their own, they correctly complete the task by cooperating through the proposed distributed algorithm
Quantum Rényi and -divergences from integral representations
No full textSmooth Csiszár -divergences can be expressed as integrals over so-called hockey stick divergences. This motivates a natural quantum generalization in terms of quantum Hockey stick divergences, which we explore here. Using this recipe, the Kullback-Leibler divergence generalises to the Umegaki relative entropy, in the integral form recently found by Frenkel. We find that the Rényi divergences defined via our new quantum -divergences are not additive in general, but that their regularisations surprisingly yield the Petz Rényi divergence for , unifying these two important families of quantum Rényi divergences. Moreover, we find that the contraction coefficients for the new quantum divergences collapse for all that are operator convex, mimicking the classical behaviour and resolving some long-standing conjectures by Lesniewski and Ruskai. We derive various inequalities, including new reverse Pinsker inequalities with applications in differential privacy and explore various other applications of the new divergences.44 pages. v2: improved results on reverse Pinsker inequalities + minor clarifications. v3: some generalizations and clarifications; published versio
A distributed, rolling-horizon demand side management algorithm under wind power uncertainty
No full textIn this paper, we consider a smart grid where users behave selfishly, aiming at minimizing cost in the presence of uncertain wind power availability. We adopt a demand side management (DSM) model, where active users (so-called prosumers) have both private generation and local storage availability. These prosumers participate to the DSM strategy by updating their energy schedule, seeking to minimize their local cost, given their local preferences and the global grid constraints. The energy price is defined as a function of the aggregate load and the wind power availability. We model the resulting problem as a non-cooperative Nash game and propose a semi-decentralized algorithm to compute an equilibrium. To cope with the uncertainty in the wind power, we adopt a rolling-horizon approach, and in addition we use a stochastic optimization technique. We generate several wind power production scenarios from a defined probability density function (PDF), determining an approximate stochastic cost function. Simulations results on a real dataset show that the proposed approach generates lower individual costs compared to a standard expected value approach.Team Bart De SchutterTeam Sergio Grammatic
DISROPT: a Python Framework for Distributed Optimization
No full textIn this paper we introduce disropt, a Python package for distributed optimization over networks. We focus on cooperative set-ups in which an optimization problem must be solved by peer-to-peer processors (without central coordinators) that have access only to partial knowledge of the entire problem. To reflect this, agents in disropt are modeled as entities that are initialized with their local knowledge of the problem. Agents then run local routines and communicate with each other to solve the global optimization problem. A simple syntax has been designed to allow for an easy modeling of the problems. The package comes with many distributed optimization algorithms that are already embedded. Moreover, the package provides full-fledged functionalities for communication and local computation, which can be used to design and implement new algorithms. disropt is available at github.com/disropt/disropt under the GPL license, with a complete documentation and many examples
Mucolipidosis II: correlation between radiological features and histopathology of the bones.
No full textTwelve cases of Mucolipidosis II (I-cell disease) with a wide range of severity of skeletal involvement were studied. Pathological findings in two cases provided helpful information in understanding the radiographic features of dysostosis multiplex. Inhibition of the growth plate cartilage calcification and rickets-like lesions were observed in the metaphyses. Enhanced subperiosteal remodelling and paratrabecular fibrosis were also evident in the diaphyses. High levels of parathormone were found in one case. This finding supports the hypothesis that bone lesions may be secondary, at least in part, to damage in such viscera as the kidney and/or the liver and that they are mediated by vitamin D and parathormone
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