Synchronized Swimming and Formation Control for Fish-inspired Underwater Vehicles

Multi-vehicle underwater control has different applications in oceanographic sampling and water pollution monitoring. Previous work in this field generated control laws that stabilizes parallel and circular formations of self-propelled particles in addition to consensus control laws in Euclidean space and nonlinear spaces. This thesis presents second order distributed control systems that generate velocity and phase consensus, parallel motion and circular motion for a number of nonlinear agents on the tangent bundle of the $N$-torus. The nonlinear agents considered in this work are underwater fish inspired vehicles modeled by Chaplygin sleigh dynamics. This work uses the Laplacian matrix of a connected interaction graph to achieve phase and velocity consensus on a periodic orbit and to generate average circular motion of all the agents on the same circle. Second, a phase potential is used to generate average parallel motion. Results are illustrated using numerical simulations

Kinematic Evaluation of 4 Pediatric Collars and Distribution of Cervical Movement Between Primary and Coupled Angles

Background: Primary and coupled angle restrictions, when neck collars are used, have been investigated mainly in adults and not yet in children. Purpose: To evaluate the efficiency of 4 pediatric collars in reducing cervical range of motion (ROM) in primary and coupled planes. Methods: Thirty asymptomatic children (16 boys and 14 girls) aged 6 to 12 years participated in the study. A motion analysis system was used to evaluate the ROM of the cervical spine during flexion/extension, left and right lateral bending, and left and right axial rotation. Primary and coupled ROM were evaluated in unbraced and braced conditions. Four cervical collars were tested: Philadelphia, Miami Jr, Necloc, and the conventional Hard Collar. Thirteen subjects were tested 2 times to evaluate the repeatability of the parameters. The ROM in each plane was normalized to the sum of the ROM in the 3 planes, for each movement, to estimate the percentage of the movement in each plane (normalized ROM), in braced and unbraced conditions. The analysis of variance and post hoc Benferroni tests were applied on raw and normalized ROM. Results: ROM collected in collars showed a significant difference compared with the unbraced condition. ROM obtained in Necloc and Miami Jr showed a significant difference compared with Philadelphia and conventional Hard Collar. The primary plane is activated at 80% during flexion-extension and left-right axial rotation; however, 55% of the total movement was completed in the frontal plane during left-right lateral bending in unbraced condition. Statistical differences in the normalized ROM were found between the braced and unbraced conditions and among collars. Conclusions: Necloc and Miami Jr presented the highest limitation of movement in the primary and secondary planes. The distribution strategy of a movement, between primary and coupled angles, is different between the braced and unbraced conditions

Exogenous Flupirtine as Potential Treatment for CLN3 Disease

CLN3 disease is a fatal neurodegenerative disorder affecting children. Hallmarks include brain atrophy, accelerated neuronal apoptosis, and ceramide elevation. Treatment regimens are supportive, highlighting the importance of novel, disease-modifying drugs. Flupirtine and its new allyl carbamate derivative (compound 6) confer neuroprotective effects in CLN3-deficient cells. This study lays the groundwork for investigating beneficial effects in Cln3Δex7/8 mice. WT/Cln3Δex7/8 mice received flupirtine/compound 6/vehicle for 14 weeks. Short-term effect of flupirtine or compound 6 was tested using a battery of behavioral testing. For flupirtine, gene expression profiles, astrogliosis, and neuronal cell counts were determined. Flupirtine improved neurobehavioral parameters in open field, pole climbing, and Morris water maze tests in Cln3Δex7/8 mice. Several anti-apoptotic markers and ceramide synthesis/degradation enzymes expression was dysregulated in Cln3Δex7/8 mice. Flupirtine reduced astrogliosis in hippocampus and motor cortex of male and female Cln3Δex7/8 mice. Flupirtine increased neuronal cell counts in male mice. The newly synthesized compound 6 showed promising results in open field and pole climbing. In conclusion, flupirtine improved behavioral, neuropathological and biochemical parameters in Cln3Δex7/8 mice, paving the way for potential therapies for CLN3 disease

Inverse Problems in a Bayesian Setting

In a Bayesian setting, inverse problems and uncertainty quantification (UQ) --- the propagation of uncertainty through a computational (forward) model --- are strongly connected. In the form of conditional expectation the Bayesian update becomes computationally attractive. We give a detailed account of this approach via conditional approximation, various approximations, and the construction of filters. Together with a functional or spectral approach for the forward UQ there is no need for time-consuming and slowly convergent Monte Carlo sampling. The developed sampling-free non-linear Bayesian update in form of a filter is derived from the variational problem associated with conditional expectation. This formulation in general calls for further discretisation to make the computation possible, and we choose a polynomial approximation. After giving details on the actual computation in the framework of functional or spectral approximations, we demonstrate the workings of the algorithm on a number of examples of increasing complexity. At last, we compare the linear and nonlinear Bayesian update in form of a filter on some examples.Comment: arXiv admin note: substantial text overlap with arXiv:1312.504

Sparse Pseudospectral Approximation Method

Multivariate global polynomial approximations - such as polynomial chaos or stochastic collocation methods - are now in widespread use for sensitivity analysis and uncertainty quantification. The pseudospectral variety of these methods uses a numerical integration rule to approximate the Fourier-type coefficients of a truncated expansion in orthogonal polynomials. For problems in more than two or three dimensions, a sparse grid numerical integration rule offers accuracy with a smaller node set compared to tensor product approximation. However, when using a sparse rule to approximately integrate these coefficients, one often finds unacceptable errors in the coefficients associated with higher degree polynomials. By reexamining Smolyak's algorithm and exploiting the connections between interpolation and projection in tensor product spaces, we construct a sparse pseudospectral approximation method that accurately reproduces the coefficients of basis functions that naturally correspond to the sparse grid integration rule. The compelling numerical results show that this is the proper way to use sparse grid integration rules for pseudospectral approximation

How Strong a Kick Should be to Topple Northeastern's Tumbling Robot?

Rough terrain locomotion has remained one of the most challenging mobility questions. In 2022, NASA's Innovative Advanced Concepts (NIAC) Program invited US academic institutions to participate NASA's Breakthrough, Innovative \& Game-changing (BIG) Idea competition by proposing novel mobility systems that can negotiate extremely rough terrain, lunar bumpy craters. In this competition, Northeastern University won NASA's top Artemis Award award by proposing an articulated robot tumbler called COBRA (Crater Observing Bio-inspired Rolling Articulator). This report briefly explains the underlying principles that made COBRA successful in competing with other concepts ranging from cable-driven to multi-legged designs from six other participating US institutions

Evidence that the C-terminal PB2-binding region of the influenza A virus PB1 protein is a discrete alpha-helical domain

AbstractThe influenza A virus RNA-dependent RNA polymerase is a heterotrimer composed of PB1, PB2 and PA subunits and essential for viral replication. However, little detailed structural information is available for this important enzyme. We show by circular dichroism spectroscopy that polypeptides from the C-terminus of PB1 that are capable of binding efficiently to PB2 fold into stable α-helical structures. Structure prediction analysis of this region of PB1 indicates that it likely consists of a three-helical bundle. Deletion of any of the helices abrogated transcriptional function. Thus, PB1 contains a C-terminal α-helical PB2-binding domain that is essential for nucleotide polymerization activity

Real-world Data of Nivolumab for Patients With Advanced Renal Cell Carcinoma in the Netherlands:An Analysis of Toxicity, Efficacy, and Predictive Markers

Background: Nivolumab, a programmed death 1 inhibitor, has been approved as second-line treatment for advanced renal cell carcinoma (RCC) in Europe since 2016. We investigated the toxicity and efficacy of nivolumab as well as potential predictive biomarkers in the Dutch population. Patients and Methods: This was a retrospective, multicenter study of the Dutch national registry of nivolumab for the treatment of advanced RCC. The main outcome parameters included toxicity, objective response rate (ORR), overall survival (OS), progression-free survival (PFS), time to progression (TTP), and time to treatment failure (TTF). In addition, potential predictive and prognostic biomarkers for outcomes were evaluated. Results: Data on 264 patients were available, of whom 42% were International Metastatic RCC Database Consortium (IMDC) poor risk at start of nivolumab, 16% had ≥ 3 lines of previous therapy, 7% had non–clear-cell RCC, 11% had brain metastases, and 20% were previously treated with everolimus. Grade 3/4 immune-related adverse events occurred in 15% of patients. The median OS was 18.7 months (95% confidence interval, 13.7-23.7 months). Progression occurred in 170 (64.4%) of 264 patients, with a 6-and 12-months TTP of 49.8% and 31.1%, respectively. The ORR was 18.6% (49 of 264; 95% confidence interval, 14%-23%). Elevated baseline lymphocytes were associated with improved PFS (P =.038) and elevated baseline lactate dehydrogenase with poor OS, PFS, and TTF (P =.000). On-treatment increase in eosinophils by week 8 predicted improved OS (P =.003), PFS (P =.000), and TTF (P =.014), whereas a decrease of neutrophils was associated with significantly better TTF (P =.023). Conclusions: The toxicity and efficacy of nivolumab for metastatic RCC after previous lines of therapy are comparable with the results in the pivotal phase III trial and other real-world data. On-treatment increase in eosinophil count is a potential biomarker for efficacy and warrants further investigation