bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the role of dachshund b in the development of the pancreatic islet in zebrafish
Authors: Yang Lingling , Webb Sarah E , Jin Nana , Lee Heung Man , Chan Ting Fung , Xu Gang , Chan Juliana CN , Miller Andrew L , Ma Ronald CW
Published: January 2021

Aims/Introduction

β‐Cell dysfunction is a hallmark of type 2 diabetes. In a previous pilot study, we identified an association between genetic variants within the human DACH1 gene and young‐onset type 2 diabetes. Here, we characterized the function of dachb, the only dach homologue to be expressed in the pancreas, in developing zebrafish embryos.

Materials and Methods

We injected one‐cell stage embryos with a dachb‐morpholino (MO) or with the dachb‐MO and dachb messenger ribonucleic acid, and determined the effect on the development of the pancreatic islet. We also carried out quantitative polymerase chain reaction and ribonucleic acid sequencing on the dachb‐MO group to determine the effect of dachb knockdown on gene expression.

Results

MO‐mediated dachb knockdown resulted in impaired islet cell development, with a significant decrease in both the β‐cell and islet cell numbers. This islet developmental defect was rescued when embryos were co‐injected with dachb‐MO and dachb messenger ribonucleic acid. Knockdown of dachb was associated with a significant downregulation of the β‐cell specific marker gene, insa, and the somatostatin cell marker, sst2, as well as regulators of pancreas development, ptf1a, neuroD, pax6a and nkx6.1, and the cell cycle gene, insm1a. Furthermore, ribonucleic sequencing analysis showed an upregulation of genes enriched in the forkhead box O and mitogen‐activated protein kinase signaling pathways in the dachb‐MO group, when compared with the control groups.

Conclusions

Together, our results suggest the possible role of dachb in islet development in zebrafish.
Marriage for the Sake of Parents? Adult Children's Marriage Formation and Parental Psychological Distress in China
Authors: Chen Dan , Tong Yuying
Published: January 2021

Objective

Drawing on the stress process from a life course perspective, this study examines the association between children's overage singlehood and parental psychological distress.

Background

Children's unfulfilled roles may have a consequence on parental well‐being. Parents may suffer from stress due to children's overage singlehood indicated by unmarried status beyond socially expected ages in some areas of the world. Parents may see it as their own failure to fulfill their parental role and children's failure to establish a family life.

Method

Drawing on data from the China Health and Retirement Longitudinal Study, this study firstly uses Inverse Probability of Treatment Weighting to handle the pretreatment bias, and it is then further advanced by testing the potential mechanisms underlying the relationship between children's marriage formation and parental well‐being.

Results

The results reveal that sons' overage singlehood is associated with a higher level of parental depression. Moreover, parental satisfaction with intergenerational relationships serves as a mediation factor between a son's overage singlehood and parents' depression. Although economic support for parents shows no significant effect on parental depression, it shows a similar pattern in reducing the effect of son's overage singlehood on parental depression.

Conclusion

These findings not only demonstrate the reluctance for cultural change in marriage formation timing and gender‐specific role expectations on children by parents, but also reveal the interplay effects of cultural continuity and the modernization process from an intergenerational perspective.
ODAM promotes junctional epithelium‐related gene expression via activation of WNT1 signaling pathway in an ameloblast‐like cell line ALC
Authors: Song Danyang , Yang Sui , Tan Tao , Wang Ruijie , Ma Zeyun , Wang Yixiang , Wang Lei
Published: January 2021

Objective

In this study, we investigated the potential and mechanism of odontogenic ameloblast‐associated protein (ODAM) in the promoting junctional epithelium‐related gene expression in an ameloblast‐like cell line ALC.

Background

ODAM is expressed in ameloblasts and JE and acts as a component of the inner basal lamina (IBL) and intercellular matrix of JE. ODAM KO mice showed destruction of the integrity of the JE, which detaches from teeth. ODAM was confirmed to regulate the cytoskeleton through the ODAM‐ARHGEF5‐RhoA signaling pathway of the JE. Whether ODAM contributes to the regulation of ameloblast differentiation in JE remains unclear. After the formation of enamel, the ameloblast undergoes a series of morphological changes. Whether ODAM will affect the biological behavior of ameloblasts making them have the characteristics of JE is unclear.

Methods

A murine ameloblast‐like cell line, ALC, was used to investigate the effects of ODAM on the JE‐like changes of ALC cells in an epithelium‐induced environment by generating ODAM overexpression and ODAM knockdown cells through a lentivirus transduction approach. The biomarkers of junctional epithelium CK19, SLPI, and ODAM and the potential regulatory gene WNT1 were investigated by real‐time PCR, western blot, immunocytochemistry, immunostaining, luciferase reporter, and rescue assays.

Results

ODAM, CK19, and SLPI were significantly upregulated after epithelial induction. Overexpression of ODAM in ALC cells markedly increased CK19 and SLPI expression, while knockdown of ODAM in ALC cells clearly decreased CK19 and SLPI expression. A reporter luciferase assay showed that ODAM activated the WNT signaling pathway, especially through WNT1. Exogenous overexpression of ODAM upregulated WNT1 expression, while knockdown of ODAM reversed this effect. The WNT1 inhibition assay further confirmed the above results and showed that the WNT1 pathway was positively correlated with biomarkers of junctional epithelium CK19 and SLPI expression. Rescue studies showed that knocking down WNT1 in the ODAM‐overexpressing ALC cells decreased the expression of CK19 and SLPI. Immunocytochemistry showed that ODAM colocalized with CK19, SLPI, and WNT1 in the cells.

Conclusion

In conclusion, the research work showed that ODAM promotes junctional epithelium‐related gene expression in ALC via the ODAM‐WNT1 axis, which may provide new insight into the function of ODAM and JE formation.
What makes a nurse today? A debate on the nursing professional identity and its need for change
Authors: van der Cingel Margreet , Brouwer Jasperina
Published: January 2021

In 2020, due to the Nightingale year and COVID‐19 crisis, nursing is in the public eye more than ever. Nurses often are being seen as compassionate helpers. The public image of nursing, however, also consists of stereotypes such as nursing being a ‘doing’ profession and care being a ‘female’ characteristic. Next to that, nursing is associated with images from the past, such as ‘the lady with the lamp’. Therefore, in the public eye at least, the nursing identity seems a simple and straightforward enough construct, but nothing less is true. Looking at what a professional identity consists of, historic and social developments influence a group identity as a construct. In addition, individual, professional and contemporary societal moralities, including stereotypes, play its role. Nurses themselves reinforce stereotypes in order to fit into what is expected, even when they believe professional behaviour encompasses other features. They may do so individually as well as in a group context. But nursing actually seems to be better off when viewed upon as a diverse, autonomous profession. Moral values such as compassion motivate nurses to enter the profession. Research shows that if such values are addressed in daily practice, nursing could perhaps be saved from nurses leaving the profession because of feeling unfulfilled. Another aspect concerns the huge nursing body of knowledge. If seen as the ground on which nursing behaviour is standing, it would contribute to a different image of nursing than simplified stereotypes, which do not acknowledge the complex nature of the profession. This paper challenges the idea that the nursing identity is unchangeable and the notion that ‘a nurse will always be a nurse’. By doing so, the paper contributes to a debate on the supposed ‘true’ nature of the nursing identity and opens a discussion on the need for it to change.
A Re‐Examination of Inflation Persistence Dynamics in OECD Countries: A New Approach*
Authors: Zsurkis Gabriel , Nicolau JoÃo , Rodrigues Paulo M. M.
Published: January 2021

This paper introduces a simple and easy to implement procedure to test for changes in persistence. The time‐varying parameter that characterizes persistence changes under the alternative hypothesis is approximated by a parsimonious cosine function. The new test is the minimum of a t‐statistic computed from a test regression that considers a set of reasonable values for a frequency term that is used to evaluate the time‐varying properties of persistence. The asymptotic distributions of the new tests are derived and critical values are provided. An in‐depth Monte Carlo analysis shows that the new procedure has important power gains when compared to the local Generalized Least Squares (GLS) de‐trended Dickey–Fuller type tests under various data generating processes with persistence changes. Moreover, an empirical application to OECD countries’ inflation shows that for most series analysed persistence was high in the first half of the sample and subsequently decreased. These results conform with modern macroeconomic theories that point to changes in inflation dynamics in the early 1980s and also with recent empirical evidence against the I(1)−I(0) dichotomy.
Medical clown support is associated with better quality of life of children with food allergy starting oral immunotherapy
Authors: Epstein Rigbi Naama , Schwartz Naama , Goldberg Michael R. , Levy Michael B. , Nachshon Liat , Elizur Arnon
Published: January 2021

Background

The start of oral immunotherapy (OIT) for food allergy is a critical period in the treatment process, with a potential to influence patient quality of life (QOL) and subsequently treatment outcome. The association of medical clowning with QOL at OIT initiation was examined.

Methods

Children aged 4‐12 years supported by a medical clown (MC) during the induction week of OIT for food allergy were studied. Children in the same age range starting OIT without the support of a MC served as controls. Parents of all children completed the Food Allergy Quality of Life Questionnaire—Parent Form (FAQLQ‐PF), and children aged 8‐12 years completed the Food Allergy Quality of Life Questionnaire—Child Form (FAQLQ‐CF). QOL scores of parents and children with and without a MC support were compared.

Results

Children with (n = 88) and without (n = 212) the support of a MC were comparable in demographics and clinical characteristics. The study group had a significantly lower single highest tolerated dose compared to controls (57 ± 83 vs 162 ± 274 mg protein, respectively, P < .001). Parental perception of the QOL of children was not associated with a MC support (P = .81) but rather with previous reaction severity (P < .01). In contrast, the QOL of children aged 8‐12 years (n = 119) was positively associated primarily with a MC support, total score 3.7 ± 1.1 vs 4.6 ± 1.3 (P < .001).

Conclusions

While the perception of QOL of parents of children with food allergy at OIT initiation is mainly associated with previous reaction severity, the QOL of the children themselves is primarily positively associated with MC support.
Strategic Waiting for Disruption Forecasts in Cross‐Border E‐Commerce Operations
Authors: Niu Baozhuang , Chen Kanglin , Chen Lei , Ding Chao , Yue Xiaohang
Published: January 2021

Motivated by dual sales channel operations in cross‐border e‐commerce, we analyze an e‐tailer's strategic waiting decision for channel disruption information in a global supply chain. The e‐tailer operates two sales channels: a bonded‐warehouse channel with products prestocked before channel disruption for demand fulfillment; and a direct‐shipping channel with products delivered directly from an overseas supplier. The direct‐shipping channel is exposed to disruption risk that might be caused by extreme weather events. Forecasts about the disruption are accurate, and the e‐tailer has the option of waiting for disruption forecasts and postponing order decisions in the bonded‐warehouse channel. We find that the e‐tailer is better off waiting if the direct‐shipping channel is either much more or much less important than the bonded‐warehouse channel. By waiting, the e‐tailer has the flexibility to adjust the stock in the bonded‐warehouse channel (depending on whether the direct‐shipping channel will be disrupted), enhancing channel coordination. However, anticipating the e‐tailer's improved channel coordination, the supplier might increase wholesale prices to extract more profits from the e‐tailer. If the direct‐shipping channel is highly important, waiting brings a significant benefit from channel coordination, offsetting the cost increase in the bonded‐warehouse channel. If the direct‐shipping channel is much less important, this channel provides the e‐tailer with leverage against the supplier in wholesale pricing; the e‐tailer waits strategically for sourcing cost reduction. This study emphasizes the role of strategic waiting for disruption information and signifies the importance of considering horizontal channel coordination and vertical interaction along supply chains.
Reliability of isokinetic tests of velocity‐ and contraction intensity‐dependent plantar flexor mechanical properties
Authors: Pinto Matheus D. , Wilson Cody J. , Kay Anthony D. , Blazevich Anthony J.
Published: January 2021

“Flexibility” tests are traditionally performed voluntarily relaxed by rotating a joint slowly; however, functional activities are performed rapidly with voluntary/reflexive muscle activity. Here, we describe the reliabilities and differences in maximum ankle range of motion (ROMmax) and plantar flexor mechanical properties at several velocities and levels of voluntary force from a new test protocol on a commercially available dynamometer. Fifteen participants had their ankle joint dorsiflexed at 5, 30, and 60° s−1 in two conditions: voluntarily relaxed and while producing 40% and 60% of maximal eccentric torque. Commonly reported variables describing ROMmax and resistance to stretch were subsequently calculated from torque and angle data. Absolute (coefficient of variation (CV%) and typical error) and relative (ICC2,1) reliabilities were determined across two testing days (≥72 h). ROMmax relative reliability was good in voluntarily relaxed tests at 30 and 60° s−1 and moderate at 5° s−1, despite CVs ≤ 10% for all velocities. Tests performed with voluntary muscle activity were only reliable when performed at 5° s−1, and ROMmax reliability was moderate and CV ≤ 8%. For most variables, the rank order of participants differed between the slow‐velocity, relaxed test, and those performed at faster speeds or with voluntary activation, indicating different information. A person's flexibility status during voluntarily relaxed fast or active stretches tended to differ from their status in the traditional voluntarily relaxed, slow‐velocity test. Thus, “flexibility” tests should be completed under conditions of different stretch velocity and levels of muscle force production, and clinicians and researchers should consider the slightly larger between‐day variability from slow‐velocity voluntarily relaxed tests.
Time‐restricted feeding combined with aerobic exercise training can prevent weight gain and improve metabolic disorders in mice fed a high‐fat diet
Authors: Vieira Renan Fudoli Lins , Muñoz Vitor Rosetto , Junqueira Rafael Lima , de Oliveira Fellipe , Gaspar Rafael Calais , Nakandakari Susana Castelo Branco Ramos , Costa Suleyma de Oliveira , Torsoni Marcio Alberto , da Silva Adelino S.R. , Cintra Dennys Esper , de Moura Leandro Pereira , Ropelle Eduardo Rochete , Zaghloul Iman , Mekary Rania A. , Pauli José Rodrigo
Published: January 2021

Key points

Time‐restricted feeding (TRF, in which energy intake is restricted to 8 h/day during the dark phase) alone or combined with aerobic exercise (AE) training can prevent weight gain and metabolic disorders in Swiss mice fed a high‐fat diet.

The benefits of TRF combined with AE are associated with improved hepatic metabolism and decreased hepatic lipid accumulation.

TRF combined with AE training increased fatty acid oxidation and decreased expression of lipogenic and gluconeogenic genes in the liver of young male Swiss mice.

TRF combined with AE training attenuated the detrimental effects of high‐fat diet feeding on the insulin signalling pathway in the liver.

Time‐restricted feeding (TRF) or physical exercise have been shown to be efficient in the prevention and treatment of metabolic disorders; however, the additive effects of TRF combined with aerobic exercise (AE) training on liver metabolism have not been widely explored. In this study TRF (8 h in the active phase) and TRF combined with AE (TRF+Exe) were compared in male Swiss mice fed a high‐fat diet, with evaluation of the effects on insulin sensitivity and expression of hepatic genes involved in fatty acid oxidation, lipogenesis and gluconeogenesis. As in previous reports, we show that TRF alone (eating only between zeitgeber time 16 and 0) was sufficient to reduce weight and adiposity gain, increase fatty acid oxidation and decrease lipogenesis genes in the liver. In addition, we show that mice of the TRF+Exe group showed additional adaptations such as increased oxygen consumption (), carbon dioxide production () and production of ketone bodies (β‐hydroxybutyrate). Also, TRF+Exe attenuated the negative effects of high‐fat diet feeding on the insulin signalling pathway (insulin receptor, insulin receptor substrate, Akt), and led to increased fatty acid oxidation (Ppara, Cpt1a) and decreased gluconeogenic (Fbp1, Pck1, Pgc1a) and lipogenic (Srebp1c, Cd36) gene expression in the liver. These molecular results were accompanied by increased glucose metabolism, lower serum triglycerides and reduced hepatic lipid content in the TRF+Exe group. The data presented in this study show that TRF alone has benefits but TRF+Exe has additive benefits and can mitigate the harmful effects of consuming a high‐fat diet on body adiposity, liver metabolism and glycaemic homeostasis in young male Swiss mice.
Exploring Applicability of Acoustic Heat Transfer Enhancement Across Various Perturbation Elements
Authors: Agarwal Tapish , Stratmann Maximilian , Julius Simon , Cukurel Beni
Published: January 2021

The requirements of improved heat transfer performance on turbine surfaces and internal cooling passages drive the research into exploring new methods for efficiency enhancements. The addition of ribbed structures inside the cooling ducts has proven to be most practical, which increases heat transfer from surfaces to fluid flow at the cost of some pressure loss. Many active and passive methods have been proposed for enhancing the heat transfer, where acoustic excitation has been recently shown to be an effective option. Moreover, the existing pressure fluctuations due to rotor–stator interactions can also be utilized as a source of excitation. However, the sensitivity of the phenomenon to various flow and geometric parameters has not been fully characterized. The present study investigates various aspects of convective heat transfer enhancement and turbulent flow modulation caused by acoustic forcing on separating and reattaching flow over isolated rib obstacles. A parametric study is conducted; rib obstacles of various sizes and shapes (including rectangular, squared, triangular, and semi-cylindrical) are installed in a low-speed, fully turbulent wind tunnel, and measurements are taken at different velocities and excitation frequencies. Static pressure and spatially resolved surface temperature measurements are performed to quantify the ramifications of acoustic excitation on the wetted wall. Within the favorable Strouhal number range of 0.1–0.25, an optimum value of 0.16 is observed. It is shown that triangular ribs are more prone to acoustic heat transfer enhancement than rectangular or cylindrical perturbations. A linear correlation between static pressure recovery rate and acoustic heat transfer enhancement is observed, which is invariant to change in size/shape of the rib as well as flow and excitation parameters.
Compact Transient Thermal Model of Microfluidically Cooled Three-Dimensional Stacked Chips With Pin-Fin Enhanced Microgap
Authors: Hu Yuanchen , Hossen Md Obaidul , Wan Zhimin , Bakir Muhannad S. , Joshi Yogendra
Published: January 2021

Three-dimensional (3D) stacked integrated circuit (SIC) chips are one of the most promising technologies to achieve compact, high-performance, and energy-efficient architectures. However, they face a heat dissipation bottleneck due to the increased volumetric heat generation and reduced surface area. Previous work demonstrated that pin-fin enhanced microgap cooling, which provides fluidic cooling between layers could potentially address the heat dissipation challenge. In this paper, a compact multitier pin-fin single-phase liquid cooling model has been established for both steady-state and transient conditions. The model considers heat transfer between layers via pin-fins, as well as the convective heat removal in each tier. Spatially and temporally varying heat flux distribution, or power map, in each tier can be modeled. The cooling fluid can have different pumping power and directions for each tier. The model predictions are compared with detailed simulations using computational fluid dynamics/heat transfer (CFD/HT). The compact model is found to run 120–600 times faster than the CFD/HT model, while providing acceptable accuracy. Actual leakage power estimation is performed in this codesign model, which is an important contribution for codesign of 3D-SICs. For the simulated cases, temperatures could decrease 3% when leakage power estimation is adopted. This model could be used as electrical-thermal codesign tool to optimize thermal management and reduce leakage power.
Analysis of Random Mechanical Vibrations in Symmetrical Thin Plates Using Full-Field Vibration Measurements
Authors: Le Bot Alain , Robin Olivier , Rouard Kevin , Berry Alain
Published: January 2021

A successful application of statistical energy analysis for analyzing energy exchanges between weakly coupled subsystems theoretically requires a diffuse vibrational field in all subsystems. So as to verify the conditions of establishment of the diffuse field in practice, full-field vibration measurements were conducted with a high-speed camera on a simply supported rectangular plate excited by a wide band random force. The results constitute an experimental investigation of the diffuse field region in the frequency-structural damping domain and a validation of previously obtained numerical results. The domain of the diffuse field is confined to high frequencies and low damping, with limits than can be easily defined. However, it is shown that the vibrational field is not fully spatially homogeneous due to enhancement of response induced by the effect of coherence of rays. Theoretical values of the enhancement factor obtained using an image source analysis are confirmed by measurement results.
Evaluation of the Rotor Temperature Distribution of an Automotive Turbocharger Under Hot Gas Conditions Including Indirect Experimental Validation
Authors: Zeh Christopher , Willers Ole , Hagemann Thomas , Schwarze Hubert , Seume Jörg
Published: January 2021

While turbocharging is a key technology for improving the performance and efficiency of internal combustion engines, the operating behavior of the turbocharger is highly dependent on the rotor temperature distribution as it directly modifies viscosity and clearances of the fluid film bearings. Since a direct experimental identification of the rotor temperature of an automotive turbocharger is not feasible at an acceptable expense, a combination of numerical analysis and experimental identification is applied to investigate its temperature characteristic and level. On the one hand, a numerical conjugate heat transfer (CHT) model of the automotive turbocharger investigated is developed using a commercial CFD-tool and a bidirectional, thermal coupling of the CFD-model with thermohydrodynamic lubrication simulation codes is implemented. On the other hand, experimental investigations of the numerically modeled turbocharger are conducted on a hot gas turbocharger test rig for selected operating points. Here, rotor speeds range from 64.000 to 168.000 rpm. The turbine inlet temperature is set to 600 °C and the lubricant is supplied at a pressure of 300 kPa with 90 °C to ensure practically relevant boundary conditions. Comparisons of measured and numerically predicted local temperatures of the turbocharger components indicate a good agreement between the analyses. The calorimetrically determined frictional power loss of the bearings as well as the floating ring speed are used as additional validation parameters. Evaluation of heat flow of diabatic simulations indicates a high sensitivity of local temperatures to rotor speed and load. A cooling effect of the fluid film bearings is present. Consequently, results confirm the necessity of the diabatic approach to the heat flow analysis of turbocharger rotors.
Control Design for an Emulator of Mechatronic Powertrain Dynamics: A Case Study
Authors: Jacobs Laurens , Janssens Dennis , Croes Jan , Desmet Wim , Swevers Jan
Published: January 2021

This paper discusses a detailed design procedure of a linear torque controller for an in-house developed lab-scale powertrain emulator. This set-up was developed for the validation of new developments in virtual torque sensing, and thus requires decent torque tracking performance in order to simulate real drivetrain dynamics sufficiently accurate. Standard proportional-integral (PI) controllers are not able to effectively compensate for potential flexible modes of the set-up, and an H∞ control approach is proposed. The different design steps then comprise experiment design, identification, feedback controller design using H∞ loop shaping, and inverse-based feedforward controller design. Experimental results demonstrate the obtained torque tracking performance.
Arm Motion Dynamics to Excite a Mobile Energy Harvesting Autowinder
Authors: George Abby , Moline David , Wagner John
Published: January 2021

A mobile energy harvester device based on the inertial automatic winding mechanism found in watches is explored. Through normal human motion during walking and running, the arm travels a spatial path that can potentially be used for energy harvesting. The conceptual harvester consists of a rotary pendulum coupled to a small generator through a step-up gear train. The generator’s electrical output may be stored and utilized as a power source for portable electronic devices that require a smaller amount of power for operation. In this paper, the equations of motion governing the human arm motion dynamics and harvester pendulum excitation are fully derived. Two cases of human walking and running are considered to analyze the system response. A series of representative simulation studies have been conducted for representative arm motion to determine the potential energy. The energy available for harvesting was greater in the case of the human subject running at 2.06 mJ, while when walking it offered an output of 0.42 mJ for a 5 second time period. The two numerical results serve as a basis for building a mobile energy harvester for future research into a renewable device that can be used by humans to augment battery life for portable electronic devices.
Further Results on Performance Guarantees in Adaptive Control of Uncertain Systems With Unmodeled Dynamics
Authors: Dogan K. Merve , Yucelen Tansel , Muse Jonathan A.
Published: January 2021

Adaptive control approaches are effective system-theoretical methods for guaranteeing both the stability and the performance of physical systems subject to uncertainties. However, the stability and performance of these approaches can be severely degraded by the presence of unmodeled dynamics. Motivated by this standpoint, the previous work of the authors introduced a model reference adaptive control architecture based on the direct uncertainty minimization method for systems with additive input uncertainties and unmodeled dynamics. In particular, the proposed approach not only guaranteed the closed-loop stability predicated on a sufficient stability condition but also improved the closed-loop performance. The purpose of this paper is to generalize this previous work of the authors. Specifically, a model reference adaptive control architecture is given and it is system-theoretically analyzed for systems with unmodeled dynamics, and both additive input and control effectiveness uncertainties (we refer to Theorems 1 and 2 of this paper). The sufficient stability condition of the resulting architecture relies on linear matrix inequalities and this architecture can be effective in achieving not only stability but also a desired level of closed-loop system performance. Finally, we also provide an illustrative numerical example, which demonstrates the given theoretical results. (This research was supported by the Air Force Research Laboratory Aerospace Systems Directorate under the Universal Technology Corporation Grant 162642-20-25-C1.)
Stability Analysis and Controller Design for Linear Time Periodic Systems Using Normal Forms
Authors: Subramanian Susheelkumar C. , Redkar Sangram
Published: January 2021

The investigation of stability bounds for linear time periodic systems have been performed using various methods in the past. The Normal Forms technique has been predominantly used for analysis of nonlinear equations. In this work, the authors draw comparisons between the Floquet theory and Normal Forms technique for a linear system with time periodic coefficients. Moreover, the authors utilize the Normal Forms technique to transform a linear time periodic system to a time-invariant system by using near identity transformation, similar to the Lyapunov Floquet (L-F) transformation. The authors employ an intuitive state augmentation technique, modal transformation and near identity transformations to enable the application of time independent Normal Forms directly without the use of detuning or book-keeping parameter. This method provides a closed form analytical expression for the state transition matrix with the elements as a function of time. Additionally, stability analysis is performed on the transformed system and the resulting transitions curves are compared with that of numerical simulation results. Furthermore, a linear feedback controller design is discussed based on the stability bounds and the implementation of an effective feedback controller for an unstable case is discussed. The theory is validated and verified using numerical simulations of temporal variation of a simple linear Mathieu equation.
Attack-Resilient Observer Pruning for Path-Tracking Control of Wheeled Mobile Robot
Authors: Zheng Yu , Anubi Olugbenga Moses
Published: January 2021

Path-tracking control of wheeled mobile robot (WMR) has gained a lot of research attention, primarily because of its wide applicability — for example intelligent wheelchairs, exploration-assistant remote WMR. Recent increase in remote and autonomous operations/requirements for WMR has led to more and more use of IoT devices within the control loop. Consequently, providing interfaces for malicious interactions through false data injection attacks (FDIA). Moreover, optimization-based FDIAs have been shown to cause catastrophic consequences in feedback control systems while by-passing any residual-based monitoring system. Since these attacks target system measurement process, this paper focuses on the problem of improving the resiliency of dynamical observers against FDIA. Specifically, we propose an attack-resilient pruning algorithm which attempts to exclude compromised channels from being processed by the observer. The proposed pruning algorithm improves attack-localization precision to 100% with high probability, which correspondingly improves the resiliency of the underlying UKF to FDIA. The improvements due to the developed resilient pruning-based observer is validated through a numerical simulation of a two-layer path-tracking control platform of differential-driven wheeled mobile robot (DDWMR) under FDIA.
Simultaneous Vibration Mitigation and Energy Harvesting for a Nonlinear Oscillator
Authors: Kakou Paul , Barry Oumar
Published: January 2021

Considerable attention has been recently given to electromagnetic resonant shunt tuned mass damper-inerter (EH-TMDI) for simultaneous vibration mitigation and energy harvesting. However, only linear structures have been investigated. Hence, in this paper, we aim at simultaneously achieving vibration mitigation and energy harvesting for nonlinear oscillators. To do so, we attach a nonlinear electromagnetic resonant shunt tuned mass damper-inerter (NEH-TMDI) to a single degree of freedom nonlinear oscillator (Duffing Oscillator). The nonlinear oscillator is coupled to the tuned mass damper via a linear and a nonlinear spring. Both the electromagnetic and the inerter devices are grounded on one side and connected to the nonlinear vibration absorber on the other side. This is done so to relax the trade off between energy harvesting and vibration suppression. The electromagnetic transducer is shunted to a resistor-inductor circuit. The governing equations of motion are derived using Newton’s method. Numerical simulations are carried out to examine the performance of the proposed NEH-TMDI. Comprehensive parametric analyses are conducted to identify the key design parameters that render the best performance of the NEH-TMDI. The results show that selected parameters offer regions were maximum energy dissipated and maximum energy harvested coincide. The findings are very promising and open a horizon of future opportunities to optimize the design of the NEH-TMDI for superior performance.
Predictive Motion Planning for Autonomous Vehicles With Geometric Constraints via Convex Optimization
Authors: Zhu Xiaoyuan , Chen Jian , Ma Yan , Deng Jianqiang , Wang Yuexuan
Published: January 2021

In this paper, we propose an MPC-based motion planning algorithm, including a decision-making module, an obstacle-constraints generating module, and an MPC-based planning module. The designed decision module effectively distinguishes between structured and unstructured roads and processes them separately, so that the algorithm is more robust in different environments. Besides, the movement of obstacles is considered in the decision-making and obstacle constraints generating module. By processing obstacles with lateral and longitudinal speed separately, obstacle avoidance can be done in scenarios with moving obstacles, including moving obstacles crossing the road. Instead of treating the vehicle as a mass point, we explicitly consider the geometric constraints by modeling the vehicle as three intersecting circles when generating obstacle constraints. This ensures that the vehicle is collision-free in motion planning, especially when the vehicle turns. For non-convex obstacle constraints, we propose an algorithm that generates up to two alternative linear constraints to convexify the obstacle constraints for improving computational efficiency. In MPC, we consider the vehicle kino-dynamic constraints and two generated linear constraints. Therefore, the proposed method can achieve better real-time performance and can be applied to more complicated traffic scenarios with moving obstacles. Simulation results in three different scenarios show that motion planning can achieve satisfactory performance in both structured and unstructured roads with moving obstacles.
Effect of Neural Network on Reduction of Noise for Edge Detection
Authors: Zhang Enqi , Peters Diane L. , Zhang James Z.
Published: January 2021

Processing photographic images is important in many applications, among them the development of automated driver assistance systems (ADAS) and autonomous vehicles. Many techniques are used for processing images, including neural networks, other types of machine learning, and edge detection. One common issue with processing these photos is the presence of noise, whether caused by the camera itself or by physical conditions (e.g., weather conditions or dirt on road signs). In this paper, a neural network is used for noise reduction to improve edge detection results and tested with two kinds of noise, Gaussian and salt & pepper noise, and three different edge detection algorithms, Canny, Sobel, and Zhang. Results showed that the noise reduction process was effective in improving performance of the edge detection process, with the exception of conditions where the noise was originally very minimal.
Dynamic Genetic Algorithm for Optimizing Movement of a Six-Limb Creature
Authors: Viaña Perez Javier , Scott Drew , Kumar Manish , Cohen Kelly
Published: January 2021

In this study we consider a Dynamic Genetic Algorithm used to optimize the movement of a symmetric six-legged creature. The optimal movement is that which advances the creature in a straight line forward with the greatest average speed. The mutation rate and crossover rate are adjusted based on number of iterations the algorithm has completed. This dynamic element was added to improve convergence rate as well as reducing the chance that the algorithm is stuck in a local optimum. The chromosomes are represented by a 2-dimensional array, where the rows represent sequences of movement. Each row defines the change in the angle for all the joints. Angular rates are restricted per joint, as well as ranges of motion. The fitness of a chromosome is determined by the resultant average speed, calculated as total displacement of the center of gravity over total time of movements in the chromosome. The results of this study show the possibility to breed mathematically the creature by using the Dynamic Genetic Algorithm proposed. This learning process converged, for all the simulations carried out, to the natural motion of six-legged beings like the ants.
Data-Driven Post-Filtering of Acoustics Noise in Atomic Force Microscope Imaging
Authors: Chen Jiarong , Zou Qingze
Published: January 2021

This paper presents a data-driven dynamics-based filtering approach to eliminate acoustic noise-caused distortion in images of atomic force microscope (AFM). AFM operations are sensitive to external noise as disturbances including acoustic noise as disturbances to the probe-sample interaction directly results in distortions in AFM imaging. Although conventional passive noise cancellation has been employed, limitation exists and residual noise still persists. Advanced online control techniques face difficulty in capturing the complex noise dynamic and limited system bandwidth imposed by the robustness requirement. Therefore, In this work, we propose a finite-impulse-response (FIR) based post-filtering approach to remove the noise-caused distortion in AFM images. Experimental implementation is presented and discussed to illustrate the proposed technique.
Continuum of Motion Equations and Control Laws for the Inverted Pendulum Cart and Rotary Pendulum
Authors: Lare Constance , White Warren N.
Published: January 2021

This paper questions whether the controller properties for a given rigid body mechanical system still apply as the given system is changed. As a first attempt in this investigation, the controller for the underactuated rotary pendulum is investigated as the system morphs into an underactuated inverted pendulum cart. As the limiting condition of the inverted pendulum cart is approached, the investigation allows the controller to also morph. The authors show that, as the pendulum base radius grows, the rotary pendulum equations of motion morph into the inverted pendulum cart dynamics. The paper presents necessary conditions for the successful morphing of the dynamic equations. The morphing process for the controller tests the idea whether the control law also satisfies the same continuum basis as the motion equations. The paper presents a framework for the class of controllers investigated for providing insight into when the controller morphing may be successful. This paper presents dimensionless quantities that render the equations of motion and controller for the inverted pendulum cart and rotary pendulum into dimensionless form. These dimensionless quantities allow comparison of controllers and systems that are not possible through simple inspection. This comparison ability is especially useful for quantifying the nonlinearities of a given system and controller compared to another system and controller having different parameter sizes, a comparison rarely seen in the control literature.
Power Management for a Fuel Cell/Battery/Supercapacitor Hybrid Locomotive
Authors: Zhao Qishen , Feng Tianheng , Chen Dongmei , Li Wei
Published: January 2021

Electrification of locomotive with hybridized fuel-cell, battery and supercapacitor has drawn much attention from both the academia and industry. Unlike traditional powertrain, hybrid powertrain consists of multiple power sources with a complex drivetrain structure, various efficiency performance, and different dynamics. Therefore, it is necessary to develop a power management strategy to make sure each power source operates under a quasi-optimal condition and maximize the overall powertrain efficiency. This paper presents the development of a power management framework for a novel hybrid locomotive consisting of PEM fuel cell, battery, and supercapacitor. Both the equivalent consumption management strategy (ECMS) and the stochastic dynamic programming (SDP) are applied to solve for the optimal power split strategy. The resulted power management strategy is presented in the form of policy maps, which makes it convenient for real-time in-vehicle implementations. Simulation results indicate that the SDP demonstrates advantages over the ECMS in terms of equivalent hydrogen consumption over typical locomotive driving cycles.
Developing an Applied Profile for Assessing the Perceived Effectiveness of Athletes’ Psychological Strategies: A Case Study at the Australian Institute of Sport
Authors: Doğan Umut
Published: January 2021

Existing tools measuring athletes’ psychological strategies have various practical limitations including (a) not capturing the perceived effectiveness of psychological strategies in pursuing desirable outcomes; (b) overlooking stages of competitive involvement, such as before training or the night before competition; (c) and being predominantly paper-based. In the present case study, the author explains the process of developing an alternative assessment tool called the Profile of Psychological Strategies (ProPS). This new profile aims to measure athletes’ perceptions of which strategies they use, to pursue which desirable outcomes, and how effectively. The ProPS has its theoretical roots in Fletcher and Sarkar’s approach to developing psychological resilience and was developed based on an adapted version of Radhakrishna’s Sequence for Instrument Development. This case study can be useful both for sport experts looking for a practical and flexible way to measure athletes’ psychological strategies and for those aiming to develop their own applied assessment tool.
High Thoracic Kyphosis and Backward Trunk Inclination Angles in the Single-Leg Standing Position Associate With Medial Elbow Injuries in Youth Baseball Players: A Cross-Sectional Study
Authors: Saito Akira , Okada Kyoji , Sato Hiromichi , Shibata Kazuyuki , Kamata Tetsuaki
Published: January 2021

Context: Baseball pitching is a coordinated movement involving the spine. A previous study indicated that increased thoracic kyphosis angle in a standing position was a risk factor for medial elbow injuries in youth baseball players. However, spinal alignments in single-leg standing and their relationships with medial elbow injuries, scapular alignment, or hip joint range of motion are unclear. Objective: To examine the difference in spinal alignment between standing and single-leg standing positions in youth baseball players and analyze their relationship with elbow injuries, scapular alignment, or hip joint range of motion. Design: Cross-sectional study. Setting: University laboratory. Participants: There were 51 youth baseball players with medial epicondylar fragmentation (medial elbow injury group) and 102 healthy youth baseball players (control group). Main Outcome Measures: Thoracic kyphosis, lumbar lordosis, and trunk inclination angles during standing and single-leg standing, forward scapular posture, and hip joint range of motion. Results: In the single-leg standing position, the thoracic kyphosis and backward trunk inclination angles were significantly higher in the medial elbow injury group than in the control group (P = .016 and P = .046, respectively). In the standing position, no significant difference was observed between both groups. The thoracic kyphosis angle in single-leg standing was positively correlated with the bilateral forward scapular posture in the medial elbow injury (P = .008 and P < .001 on the throwing and nonthrowing sides, respectively) and control (P = .010 and P = .032 on the throwing and nonthrowing sides, respectively) groups. Conclusions: High thoracic kyphosis and backward trunk inclination angles are characteristics during single-leg standing in youth baseball players with medial elbow injuries. Spinal alignment measurement in single-leg standing may be useful for identifying youth baseball players who are at risk for sustaining medial elbow injury.
Decreased Ecological Resistance of the Gut Microbiota in Response to Clindamycin Challenge in Mice Colonized with the Fungus Candida albicans
Authors: Markey Laura , Pugliese Antonia , Tian Theresa , Roy Farrah , Lee Kyongbum , Kumamoto Carol A.
Published: January 2021

Candida albicans
is the most common fungal member of the human gut microbiota, yet its ability to interact with and affect the bacterial gut microbiota is largely uncharacterized. Previous reports showed limited changes in microbiota composition as defined by bacterial species abundance as a consequence of
C. albicans
colonization.
Specific Norovirus Interaction with Lewis x and Lewis a on Human Intestinal Inflammatory Mucosa during Refractory Inflammatory Bowel Disease
Authors: Tarris Georges , de Rougemont Alexis , Estienney Marie , Charkaoui Maeva , Mouillot Thomas , Bonnotte Bernard , Michiels Christophe , Martin Laurent , Belliot Gaël
Published: January 2021

Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are progressive diseases affecting millions of people each year. Flare-ups during IBD result in severe mucosal alterations of the small intestine (in CD) and in the colon and rectum (in CD and UC).