In this article, we present a novel ultrawideband (UWB)-inertial measurement unit (IMU)-odometer fusion localization scheme for nonholonomic ground robots in global positioning system (GPS)-denied ...environments. To overcome the severe drift problems caused by the large acceleration bias of low-cost IMUs, rather than using the conventional IMU-only propagation model, a wheel odometer and a three-axis gyroscope are integrated to propagate the system states. Furthermore, the observability conditions of the proposed system with nonholonomic constraints are theoretically derived by a nonlinear observability analysis. The results reveal the minimum number of anchors (or leader robots) required for position observability (at least three anchors for UWB-time of arrival (ToA) measurements and one anchor for both ToA and angle-of-arrival (AOA) measurements). In addition, the system inputs (linear velocity and angular velocity along different axes) need to be excited for attitude observability. Simulations and experiments have verified that the proposed approach produces accurate position estimation and outperforms previous methods. Meanwhile, the position and attitude observability conditions have been verified through rich experiments, and the degenerated cases where the states cannot be observed are enumerated and tested, making the scheme complete.
Self-locking origami structures are characterized by their piecewise linear constitutive relations between force and deformation, which, in practice, are always completely opaque and unmeasurable: ...the number of piecewise segments, the positions of non-smooth points, and the linear parameters of each segment are unknown a priori. However, acquiring this information is of fundamental importance for understanding the origami structure’s dynamic folding process and predicting its dynamic behaviors. This, therefore, arouses our interest in adopting a dynamical identification process to determine the model and to estimate the parameters. In this research, based on the piecewise linear assumption, a physically-interpretable neural-fuzzy network is built to correlate the measured input and output data. Unlike the conventional approaches, the constructed neural network possesses specific physical meaning of its components: the number of neurons relates to the number of piecewise segments, the coefficients of the local linear models relate to the parameters of the constitutive relations, and the validity functions relate to the positions of non-smooth points. By addressing several examples with different backgrounds, the network’s underlying data training methods are illustrated, including the local linear optimization for linear parameters, nested optimization for nonlinear partitions, and Local Linear Model Tree optimization for model selection. Noting that the tackled origami problem holds strong universality in terms of the unknown piecewise characteristics, the proposed approach would thus provide an effective, generic, and physically significant means for handling piecewise linear dynamical systems and meanwhile bring fresh vitality to the artificial neural network research.
Infection with the human immunodeficiency virus (HIV) and lung cancer represent two problems beginning in the 20th century that are of epidemic proportions. By the end of the 20th century, ...therapeutic programs of modest efficacy had been developed for both. Because both HIV infection and lung cancer are common, it is not surprising that a number of patients would be afflicted with both diseases simultaneously. There is a very limited literature regarding the treatment and outcome of patients with both diseases, particularly since the advent of highly active antiretroviral therapy (HAART) for HIV infection.
We retrospectively reviewed our tumor registry to ascertain cases with concurrent lung cancer and HIV diagnoses since 1996, at the advent of HAART. Twenty-nine patients were identified at the University of Maryland, and five additional cases from an affiliated institution were identified.
Thirty patients had non-small cell lung cancer, and four patients had small cell lung cancer. Of the 30 patients with non-small cell lung cancer, 27 had stage IIIb/IV disease and were analyzed for outcome on the basis of CD4 counts and HAART therapy. Patients with CD4 counts >200 or those on HAART had numerically, though not statistically, superior survival. Patients were able to receive standard chemotherapy regimens, and the overall survival was 5.2 months.
This single-institution analysis appears to indicate that there is an increasing incidence of patients with lung cancer and HIV infection. Patients with advanced NSCLC who are HIV positive with CD4 counts >200 can be treated with chemotherapy and demonstrate survival comparable to that of patients without HIV infection.
Self-locking degree-4 vertex origami structures Fang, Hongbin; Li, Suyi; Wang, K. W.
Proceedings of the Royal Society. A, Mathematical, physical, and engineering sciences,
11/2016, Letnik:
472, Številka:
2195
Journal Article
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A generic degree-4 vertex (4-vertex) origami possesses one continuous degree-of-freedom for rigid folding, and this folding process can be stopped when two of its facets bind together. Such ...facet-binding will induce self-locking so that the overall structure stays at a pre-specified configuration without additional locking elements or actuators. Self-locking offers many promising properties, such as programmable deformation ranges and piecewise stiffness jumps, that could significantly advance many adaptive structural systems. However, despite its excellent potential, the origami self-locking features have not been well studied, understood, and used. To advance the state of the art, this research conducts a comprehensive investigation on the principles of achieving and harnessing self-locking in 4-vertex origami structures. Especially, for the first time, this study expands the 4-vertex structure construction from single-component to dual-component designs and investigates their self-locking behaviours. By exploiting various tessellation designs, this research discovers that the dual-component designs offer the origami structures with extraordinary attributes that the single-component structures do not have, which include the existence of flat-folded locking planes, programmable locking points and deformability. Finally, proof-of-concept experiments investigate how self-locking can effectively induce piecewise stiffness jumps. The results of this research provide new scientific knowledge and a systematic framework for the design, analysis and utilization of self-locking origami structures for many potential engineering applications.
Both epigenetic alterations and genetic variations play essential roles in tumorigenesis. The epigenetic modification of DNA methylation is catalyzed and maintained by the DNA methyltransferases ...(DNMT3a , DNMT3b and DNMT1). DNA mutations and DNA methylation profiles of DNMT s themselves and their relationships with chicken neoplastic disease resistance and susceptibility are not yet defined. In the present study, we analyzed the complexity of the DNA methylation variations and DNA mutations in the first exon of three DNMT s genes over generations, tissues, and ages among chickens of two highly inbred White Leghorn lines, Marek's disease-resistant line 6 3 and -susceptible line 7 2 , and six recombinant congenic strains (RCSs). Among them, tissue-specific methylation patterns of DNMT3a were disclosed in spleen, liver, and hypothalamus in lines 6 3 and 7 2 . The methylation level of DNMT3b on four CpG sites was not significantly different among four tissues of the two lines. However, two line-specific DNA transition mutations, CpG→TpG (Chr20:10203733 and 10203778), were discovered in line 7 2 compared to the line 6 3 and RCSs. The methylation contents of DNMT1 in blood cell showed significant epimutations in the first CpG site among the two inbred lines and the six RCSs (P <0.05). Age-specific methylation of DNMT1 was detected in comparisons between 15 month-old and 2 month-old chickens in both lines except in spleen samples from line 7 2 . No DNA mutations were discovered on the studied regions of DNMT1 and DNMT3a among the two lines and the six RCSs. Moreover, we developed a novel method that can effectively test the significance of DNA methylation patterns consisting of continuous CpG sites. Taken together, these results highlight the potential of epigenetic alterations in DNMT1 and DNMT3a , as well as the DNA mutations in DNMT3b , as epigenetic and genetic factors to neoplastic diseases of chickens.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Vibration-driven locomotion systems have great potential for designing micro locomotion robots, and improving the locomotion performance is one of the research focuses. This paper investigates how to ...integrate bistability with the vibration-driven mechanism to form novel designs and to enhance the locomotion performance, thereby advancing the current state of the art. To this end, a two-module vibration-driven robot with a bistable pre-buckling beam is designed, which is equivalently modeled into a nonlinear lumped-mass system. Its steady-state locomotion is first approximated through the harmonic balance (HB) method, and the results show that the presence of the sticking behavior caused by the dry friction prevents the HB method from accurately predicting the robot's velocity. Hence, numerical approaches are employed in this research, which not only reveals the effects of the actuation parameters on the bistable dynamics and the steady-state locomotion performance of the robot, but also uncovers the unique advantages that the bistability brings to the robot. On one hand, the robot can present different locomotion modes corresponding to different levels of the average steady-state velocity and can switch among them without increasing the actuation energy; on the other hand, the robot can adapt to variable payloads and maintain high speeds. Based on a bistable two-module vibration-driven robot prototype, these bistability-induced characteristics and merits are verified experimentally. The findings of this paper would provide a design basis and useful guidelines for the development of bistable vibration-driven locomotion robot.
•The effects of inter-cell connections on multi-cell origami dynamics are studied.•A refined and processible dynamic model of dual-cell SMO structures is developed.•The differences are revealed in ...terms of configuration switches and response types.•Global dynamics are examined via basins of attraction and basin stability.•Dynamic experiments verify the predicted connection-induced differences.
Origami has become an important source for the development of mechanical metamaterials because folding can often lead to enhanced or unconventional mechanical properties. Metamaterials are always made of repeating cells by stacking and tessellating. The inter-cell connection thus plays a key role in determining the overall mechanics and dynamics of the metamaterial, but current studies mainly focus on the effects of inter-cell connection on statics. To overcome the shortcomings and advance the state of the art, this research employs the dual-cell stacked Miura-origami (SMO) structure as a platform to comprehensively dissect the effects of inter-cell connection forms on the dynamics. The two constituent SMO cells, by design, can be bi-stable such that the dual-cell structure possesses four stable states that are fundamentally different in configuration. Two inter-cell connection forms, a rod connection and a crease connection, are examined both theoretically and experimentally in this research. Assuming rigid-foldability of the constituent SMO structures and by equivalently quantifying the inter-cell connection constraint via additional elastic potential energy, a refined and processible dynamic model of the multi-stable dual-cell SMO structure is developed. Comprehensive numerical calculations reveal, on the one hand, the rich and complex dynamics of the dual-cell structure and, on the other hand, uncover the significant differences caused by the inter-cell connection forms. With relatively weak inter-cell constraint (e.g., the rod connection), dynamic configuration switches would occur at low excitation amplitudes, and the dynamic response types of the two cells can be fundamentally different; however, with relatively strong inter-cell constraint (e.g., the crease connection), more energy input is required to switch the configuration, and the dynamic response types of the two cells remain consistent. Such findings are qualitatively verified via dynamic experiments on the dual-cell SMO structures. We also extend our research to global dynamics by analyzing the basins of attraction and basin stability, which demonstrates from a probabilistic viewpoint that stronger inter-cell constraint would converge the dynamics to synchronous response types. The results of this research would offer a solid foundation for regulating the multi-stable dynamics of multi-cell origami structures/metamaterials and advancing their dynamic applications.
The generation of intentional delay in response to the stride frequency is seldom considered in prosthesis-human symbiosis. Unfortunately, such intentionally delayed human-robot interaction poses a ...new challenge to their gait coordination in stochastic environments. Utilizing fuzzy logic systems (FLSs), we investigate an adaptive fuzzy finite-time control of a stochastic prosthesis-human symbiosis with intentional delay to address this issue. Noting that the intentional delay is related to walking velocity, this work conducts experiments on ten healthy subjects to identify the intentional delays at different velocities using the FLS. Introducing the FLS-identified delay and contralateral healthy limb gaits, we propose a prosthetic gait planner to simultaneously determine the reference stride frequency and stride length, thus properly regulating the desired velocity. Considering the adverse effects of the required intentional delay and state constraints in the stochastic framework, we propose a new statistical Lyapunov-Krasovskii functional, together with a Tan-type barrier Lyapunov function. Correspondingly, an adaptive fuzzy controller is developed via a backstepping design, thus solving the semi-global finite-time stable in probability with intentional delay, unknown nonlinearities, and state constraints. Application studies validate the efficacy of the proposed approach. The results show that our approach can predict walking behavior while performing gait coordination.
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