State Space Modeling and Estimation of Flexible Structure Using the Theory of Functional Connections

In this work, we present a novel method to model the dynamics of a continuous structure based on measurements taken at discrete points. The method is conceived to provide new instruments to address the problem of flexible dynamics modeling in a spacecraft, where an effective mathematical representation of the non-rigid behavior of the is of critical importance in the design of an effective and reliable attitude estimation and control system. Both the measurements and the model that describes the structure can be affected by uncertainty. The purpose of the developed method is to estimate the position and the velocity of any point of the physical domain relying on a limited number of measurements while filtering out the noise. To this aim, the well-assessed Kalman filter is used in synergy with the recently developed Theory of Functional Connections (TFC). This is a mathematical framework to perform functional interpolation with applications in many fields being currently discovered and investigated. Initially, an algorithm for the solution of the corresponding static problem was developed based on the TFC; the results of the tests were promising and the approach presented in this work constitutes an effort to extend the idea to the dynamic case. In the proposed method, the continuous structure is approximated by the TFC constrained expression, while the system state variables are defined as the coefficients used to represent the free function in a basis of orthogonal polynomials. This leads to a system that, despite being continuous and thus formed of an infinite number of material points, is modeled using a finite number of state variables allowing for the use of Kalman filter to deal with the uncertainties intrinsic in both the modeling and measurements. This is accomplished by exploiting the original structure model Differential Equation(s) to obtain a process model for the filter and using the constrained expression itself as the measurement model. Then the Kalman filter algorithm is applied and the a posteriori estimates of the state variables (that is the free function coefficients) can be used to build the TFC expression that approximates the instantaneous shape of the structure, thus enabling the evaluation of the displacement at any point of the domain. The power of the proposed method is twofold. First, an estimate of the displacements of all the points is obtained based on a limited number of noisy measurements. Second, the relation between discrete measurements and continuous displacement field always accounts for the real physics of the problem. In this paper, the theoretical developments of the proposed approach are shown along with the results of numerical simulations showing the effectiveness of the method in estimating the actual dynamics of a Euler-Bernoulli beam. The technique yielded good results both for the free response and in the case of a forcing input to the system

Growth and instability of a laminar plume in a strongly stratified environment

Experimental studies of laminar plumes descending under gravity into stably stratified environments have shown the existence of a critical injection velocity beyond which the plume exhibits a bifurcation to a coiling instability in three dimensions or a sinuous instability in a Hele-Shaw flow. In addition, flow visualization has shown that, prior to the onset of the instability, a stable base flow is established in which the plume penetrates to a depth significantly smaller than the neutral buoyancy depth. Moreover, the fresh water that is viscously entrained by the plume recirculates within a ‘conduit’ whose boundary with the background stratification appears sharp. Beyond the bifurcation, the buckling plume takes the form of a travelling wave of varying amplitude, confined within the conduit, which disappears at the penetration depth. To determine the mechanisms underlying these complex phenomena, which take place at a strikingly low Reynolds number but a high Schmidt number, we study here a two-dimensional arrangement, as it is perhaps the simplest system which possesses all the key experimental features. Through a combination of numerical and analytical approaches, a scaling law is found for the plume’s penetration depth within the base flow (i.e. the flow where the instability is either absent or artificially suppressed), and the horizontal cross-stream velocity and concentration profile outside the plume are determined from an asymptotic analysis of a simplified model. Direct numerical simulations show that, with increasing flow rate, a sinuous global mode is destabilized giving rise to the self-sustained oscillations as in the experiment. The sinuous instability is shown to be a consequence of the baroclinic generation of vorticity, due to the strong horizontal gradients at the edge of the conduit, a mechanism that is relevant even at very low Reynolds numbers. Despite the strength of this instability, the penetration depth is not significantly affected by it, instead being determined by the properties of the plume in the vicinity of the source. This scenario is confirmed by a local stability analysis. A finite region of local absolute instability is found near the source for sinuous modes prior to the onset of the global instability. Sufficiently far from the source the flow is locally stable. Near the onset of the global instability, varicose modes are also found to be locally, but only convectively, unstable

The WEB-based Asthma Control: An intriguing connection or a dangerous hazard?

Globally, an estimated 300 million people have asthma, presenting a considerable and increasing burden of disease for healthcare systems, families, and patients themselves. Despite two decades of guidelines, asthma seems to remain not optimally controlled in a substantial proportion of people. The achievement of asthma control is the result of the interaction among different variables concerning the disease pattern and patients' and physicians' knowledge and behavior. It is well known that adherence to treatment increases in parallel to patient education. There is now a growing interest in the use of digital information technologies to promote asthma control and improve outcomes. Mobile health, or mHealth, refers to mobile devices, medical sensors, and communication technologies that can enhance chronic disease care and monitoring. Aim of this review was to evaluate the web resources nowadays available and to analyze the published studies about the web-based instruments used to improve asthma knowledge, control asthma outcomes. In general, studies revealed that the technology is well accepted. Interactive asthma technology may be, in addition, of help in reaching populations difficult to reach, such as inner city populations. The number of tools and apps available continues to increase, and agencies such as the FDA, become involved in their regulation, thus the mHealth landscape will continue to evolve. Although asthma tools and apps have great potential to improve care for asthma, the proof of data reproducibility, the demonstration of effectiveness, and the privacy issues still represent the major technical problems

Nitric Oxide And Hydrogen Peroxide Involvement During Programmed Cell Death Of Sechium Edule Sw. Nucellus

The nucellus is a maternal tissue that feeds the developing embryo and the secondary endosperm. During seed development the cells of the nucellus suffer a degenerative process early after fertilization as the cellular endosperm expands and accumulates reserves. Nucellar cell degeneration has been characterized as a form of developmentally programmed cell death (PCD). In this work we show that nucellus PCD is accompanied by a considerable production of both nitric oxide and hydrogen peroxide (NO and H(2)O(2)). Interestingly, each of the two molecules is able to induce the production of the other and to cause cell death when applied to a living nucellus. We show that the induced cell death has features of a PCD, accompanied by profound changes in the morphology of the nuclei and by a massive degradation of nuclear DNA. Moreover, we report that NO and H(2)O(2) cause an induction of caspase-like proteases previously characterized in physiological nucellar PCD. Document Type: Articl

Morbidity of central neck dissection for papillary thyroid cancer

Thyroid cancer has a very well-known propensity for nodal involvement, either in the central and lateral neck compartments. Neck dissection addressing the central compartment may be performed with an elective or therapeutic intent, the former concomitantly to a thyroidectomy whereas the latter may be accomplished also as a revision procedure for recurrent disease. In this paper complications of central compartment neck dissection will be described, analyzing separately primary and revision procedures

The perception of allergen-specific immunotherapy among pediatricians in the primary care setting

Background: Allergic respiratory diseases are constantly increasing in prevalence. Allergen Immunotherapy (AIT) represent a valuable therapeutic tool as symptomatic and preventative approach, expecially in children. In Italy, primary care pediatricians (PCP) represent the first-line contact and interface for prescription, use and management of AIT. We attempted to evaluate the perception of AIT practice among PCP. Methods: A questionnaire was built-up, based on literature, guidelines and with the contribution of pediatricians. The questionnaire, including 12 items, was e-mailed to 180 PCP, randomly chosen from mailing lists. The questionnaire explored the personal perception of AIT, the comparison between subcutaneous and sublingual AIT and the overall awareness about the treatment. Results: 130 questionnaires were eligible for analysis. There was a satisfactory knowledge of the characteristics of AIT, its aims and limits, although the positioning of the treatment in guidelines was insufficiently known. Overall, the prescription of AIT made by other specialists was accepted and agreed (78 %). The majority of pediatricians felt that a more intense divulgation and information about AIT would be needed (90 %). Conclusion: AIT is in general well known and accepted among PCP, although a more intense divulgation effort is required

The patient with rhinitis in the pharmacy. A cross-sectional study in real life

In the practical management of allergic rhinitis (AR), pharmacists are usually the first-line contact, also because some medications are available as over the counter. Therefore, pharmacists may represent an important resource, in mediating the interaction between patients and physicians. We evaluated the clinical/demographic characteristics of patients with respiratory allergies who consulted their pharmacists as first-line contact. A patient-oriented questionnaire was developed by a scientific committee including pharmacists, GPs, allergists, pulmonologists and ENT specialists

Red cell distribution width and chronic heart failure: prognostic role beyond echocardiographic parameters.

Aim. Red cell distribution width (RDW) is a measure of anisocytosis. Higher values are robustly associated to adverse outcome in several conditions, including chronic heart failure (HF). The present study aimed to compared its prognostic role with that of echocardiographic parameters in this kind of patients. Methods. 232 stable and optimally treated chronic HF patients were enrolled. We excluded subjects suffering from valvular diseases or atrial fibrillation. They underwent blood sampling and echocardiographic examination. The primary endpoint of the study was cardiovascular death and/or HF hospitalization in the first year after enrolment. Results. 49 patients reached the primary endpoint. RDW best cut-off at ROC curve was 14.45%. Univariate analysis associated mitral regurgitation grade, left ventricular ejection fraction (LVEF), posterior wall thickness (PWT), LV mass index, and RDW&gt;14.45% to the primary endpoint. Multivariate regression analysis showed that LVEF, PWT, and RDW&gt;14.45% predict the primary endpoint. Area under ROC curve was 0.808 for LVEF, 0.762 for NYHA class, and 0.761 for RDW. Conclusion. In chronic HF patients RDW is a better predictor of adverse outcome than several echocardiographic parameters associated to outcome itself (LV mass index, mitral regurgitation grade), predicts prognosis even adjusting for those parameters, age and NYHA class, and is associated to several echocardiographic measurements. In conclusion, RDW can expand our tool bag in order to better follow-up these patients.</p