Crumpling of a stiff tethered membrane

first-principles numerical simulation model for crumpling of a stiff tethered membrane is introduced. In our model membranes, wrinkles, ridge formation, ridge collapse, as well as the initiation of stiffness divergence, are observed. The ratio of the amplitude and wave length of the wrinkles, and the scaling exponent of the stiffness divergence, are consistent with both theory and experiment. We observe that close to the stiffness divergence there appears a crossover beyond which the elastic behavior of a tethered membrane becomes similar to that of dry granular media. This suggests that ridge formation in membranes and force-chain network formation in granular packings are different manifestations of a single phenomenon.Comment: For full resolution figures, please send us an emai

Spin wave dispersion softening in the ferromagnetic Kondo lattice model for manganites

Spin dynamics is calculated in the ferromagnetic (FM) state of the generalized Kondo lattice model taking into account strong on-site correlations between e_g electrons and antiferromagnetic (AFM) exchange among t_{2g} spins. Our study suggests that competing FM double-exchange and AFM super-exchange interaction lead to a rather nontrivial spin-wave spectrum. While spin excitations have a conventional Dq^2 spectrum in the long-wavelength limit, there is a strong deviation from the spin-wave spectrum of the isotropic Heisenberg model close to the zone boundary. The relevance of our results to the experimental data are discussed.Comment: 6 RevTex pages, 3 embedded PostScript figure

Some Practical Applications of Dark Matter Research

Two practical spin-offs from the development of cryogenic dark matter detectors are presented. One in materials research, the other in biology.Comment: 8 pages,4 figure

Childhood negative dental experiences and tooth loss in later life:A 25-year longitudinal study in Sweden

OBJECTIVE: To explore the association between childhood NDEs and changes in tooth loss over 25 years among Swedish older adults, and the role of dental visits in explaining such an association.METHODS: We used data from 6154 adults, members of a cohort study that started in 1992 when participants were 50 years old. All data were self-reported through postal questionnaires (6 in total, one every 5 years). Information on childhood NDEs was collected at baseline only. Tooth loss was the repeated outcome measure. Mixed effects logistic regression models were used to test the association between childhood NDEs and tooth loss adjusting for confounders.RESULTS: Childhood NDEs was positively associated with greater odds of experiencing tooth loss and its rate of change over the 25-year period. Although having a dental visit within the past year was positively associated with childhood NDEs and inversely associated with incidence of tooth loss, it explained very little of the association between childhood NDEs and tooth loss in later life.CONCLUSION: The findings underscore the long-lasting damaging effects of early life NDEs on adult oral health.CLINICAL SIGNIFICANCE: A positive patient-dentist relationship starts early in life. Early visits to the dentist are essential to build an enduring relationship of trust between people and healthcare providers.</p

Resilient Parameter-Invariant Control With Application to Vehicle Cruise Control

This work addresses the general problem of resilient control of unknown stochastic linear time-invariant (LTI) systems in the presence of sensor attacks. Motivated by a vehicle cruise control application, this work considers a first order system with multiple measurements, of which a bounded subset may be corrupted. A frequency-domain-designed resilient parameter-invariant controller is introduced that simultaneously minimizes the effect of corrupted sensors, while maintaining a desired closed-loop performance, invariant to unknown model parameters. Simulated results illustrate that the resilient parameter-invariant controller is capable of stabilizing unknown state disturbances and can perform state trajectory tracking

Active Learning in Persistent Surveillance UAV Missions

The performance of many complex UAV decision-making problems can be extremely sensitive to small errors in the model parameters. One way of mitigating this sensitivity is by designing algorithms that more effectively learn the model throughout the course of a mission. This paper addresses this important problem by considering model uncertainty in a multi-agent Markov Decision Process (MDP) and using an active learning approach to quickly learn transition model parameters. We build on previous research that allowed UAVs to passively update model parameter estimates by incorporating new state transition observations. In this work, however, the UAVs choose to actively reduce the uncertainty in their model parameters by taking exploratory and informative actions. These actions result in a faster adaptation and, by explicitly accounting for UAV fuel dynamics, also mitigates the risk of the exploration. This paper compares the nominal, passive learning approach against two methods for incorporating active learning into the MDP framework: (1) All state transitions are rewarded equally, and (2) State transition rewards are weighted according to the expected resulting reduction in the variance of the model parameter. In both cases, agent behaviors emerge that enable faster convergence of the uncertain model parameters to their true values

EQ-5D-Y-5L: developing a revised EQ-5D-Y with increased response categories.

Kreimeier S, Astrom M, Burstrom K, et al. EQ-5D-Y-5L: developing a revised EQ-5D-Y with increased response categories. Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation. 2019;28(7):1951-1961.PURPOSE: EQ-5D-Y is a generic measure of health status for children and adolescents aged 8-15 years. Originally, it has three levels of severity in each dimension (3L). This study aimed to develop a descriptive system of EQ-5D-Y with an increased number of severity levels and to test comprehensibility and feasibility. METHODS: The study was conducted in Germany, Spain, Sweden and the UK. In Phase 1, a review of existing instruments and focus group interviews were carried out to create a pool of possible labels for a modified severity classification. Participants aged 8-15 rated the severity of the identified labels in individual sorting and response scaling interviews. In Phase 2, preliminary 4L and 5L versions were constructed for further testing in cognitive interviews with healthy participants aged 8-15 years and children receiving treatment for a health condition. RESULTS: In Phase 1, a total of 233 labels was generated, ranging from 37 (UK) to 79 labels (Germany). Out of these, 7 to 16 possible labels for each dimension in the different languages were rated in 255 sorting and response scaling interviews. Labels covered an appropriate range of severity on the health continuum in all countries. In Phase 2, the 5L version was generally preferred (by 68-88% of the participants per country) over the 4L version. CONCLUSIONS: This multinational study has provided a version of the EQ-5D-Y with 5 severity levels in each dimension. This extended version (EQ-5D-Y-5L) requires testing its psychometric properties and its performance compared to that of the original EQ-5D-Y-3L

A method for the reconstruction of unknown non-monotonic growth functions in the chemostat

We propose an adaptive control law that allows one to identify unstable steady states of the open-loop system in the single-species chemostat model without the knowledge of the growth function. We then show how one can use this control law to trace out (reconstruct) the whole graph of the growth function. The process of tracing out the graph can be performed either continuously or step-wise. We present and compare both approaches. Even in the case of two species in competition, which is not directly accessible with our approach due to lack of controllability, feedback control improves identifiability of the non-dominant growth rate.Comment: expansion of ideas from proceedings paper (17 pages, 8 figures), proceedings paper is version v