Backward Cycle Research Articles

A backward cycling programme for people with Parkinson's disease: a feasibility and preliminary results study.

To assess the feasibility of backward cycling for people with Parkinson's disease. Secondary objectives were to assess changes in gait and balance following a 6-week program. A single-group prospective pre-test, post-test study with 1-month follow-up. Twenty-six people with Parkinson's disease (mean age: 69 (7.74) years, gender: 83% males, time since diagnosis: 6 (4.44) years). Participants pedaled backward on a stationary bicycle for 30 minutes at moderate intensity twice a week for 6 weeks. Feasibility was assessed by acceptability, suitability, and burden. Data collected at pre- and post-intervention with 1-month follow-up included backward stepping response variables, forward/backward gait variables, Mini-Balance Evaluation Systems Test (MBT), and 6 Minute Walk Test. There was a high retention rate (95.8%) and adherence rate (100%) with one adverse event and minimal burden. Significant improvements were seen in step count and excursion distance during backward stepping responses, forward and backward gait velocity, forward step length, and the Mini-BESTest. Backward cycling was a feasible intervention for people with Parkinson's disease, demonstrating low burden with high retention and adherence rates, and it is a safe exercise with the potential for benefits in gait and balance variables.

Impact of Stationary Cycling on Clinical Outcomes in Patients with Tibiofemoral Osteoarthrosis: A Pilot Study

Introduction: Knee osteoarthrosis (tibiofemoral) is one of the most common forms of arthritis and a significant contributor to disability in the elderly. It has a notable impact on the muscle strength and lower limb biomechanics. The pain and stiffness associated with osteoarthrosis knee can significantly hinder daily activities and work potential in affected individuals. Aerobic exercises have demonstrated positive outcomes for these patients. Aim: To evaluate the effectiveness of forward and backward cycling with knee osteoarthrosis ranging from grade 1-3. Materials and Methods: A prospective, randomised clinical trial and single-blind pilot study was conducted in the Department of Physiotherapy, Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, India. The compared two groups: one adding static cycling to regular treatment, the other receiving only regular treatment. Both groups got treatment three times a week for four weeks. Quality of Life (QoL) and pain were assessed using the Comprehensive Knee Osteoarthritis Index (CKOAI) scale, while isokinetic strength was measured with an isokinetic dynamometer. Evaluation at both baseline and endpoint was conducted by the same assessor. Results: Significant improvements were shown at the 4-week follow up for QOL, pain and isokinetic strength (p<0.02) with stationary cycling. The CKOAI, an indicator of pain intensity and QOL showed significant improvement (p=0.02). Conclusion: The research affirms the findings from the earlier Randomised Controlled Trials (RCTs) and indicated that engaging in stationary cycling leads to significant enhancement in individuals with osteoarthrosis knee. Participants expressed their appreciation for the program and proved to be safe, effective and feasible in primary care.

Mathematical modelling of terrorists re-cycle induced with backward bifurcation

In this work, we formulate a deterministic mathematical model that aims at controlling and preventing terrorism in a population. The model incorporates the prevention of the spread of terrorists in the population by imprisoning individuals caught in the act and allows for natural repentance from terrorism. The main aim of the study is to assess the effect of re-cycling terrorists on the bifurcation phenomena of the model. The model exhibits a backward bifurcation phenomenon. These may have serious implications for the design of intervention programs aiming at eradicating the menace of terrorism. When the values of the scaling factor of the re-cycling rate change from 0 to 1, the bifurcation changes from backward to forward. One or more stable endemic equilibria coexist alongside the stable terrorists-free equilibrium (TFE). It is further demonstrated that the recycling of terrorists who have repented from the terrorism act is what triggers the backward bifurcation cycle. This conclusion is important because it shows that eliminating terrorists from the population is no longer dependent on the old precondition of the basic reproduction number being less than one. The parameter of recycling is deleted, and the model is examined, to determine the reason why this model exhibits a backward bifurcation phenomenon. By taking into account the importance of the original model, this was made achievable. When the terrorists aren’t recycled, the second model will demonstrate a forward bifurcation, according to an analysis of the second model’s coefficient of bifurcation, which is negative.

Dynamical systems theory analyses reveal cell cycle-coupled paths of epithelial-to-mesenchymal transition.

Epithelial to mesenchymal transition, EMT, is involved in numerous biological processes such as wound healing, tissue fibrosis, and cancer metastasis. Existing literatures have been debated on whether the transition proceeds through a single or multiple paths, and how cell cycle couples to EMT. To address the above questions, we first generated scRNA-seq dataset, where mammary epithelial MCF10A cells were treated with different doses of TGFβ, an EMT inducer. Then we analyzed the data with dynamo, a machine-learning based analytical framework we developed to reconstruct single cell dynamical equations (Qiu et al. Cell, 2022, 185: 690-711). From the obtained vector fields, we applied the transition path analyses, which are originally developed in studying chemical reactions, on simulated single cell trajectories. The analyses reveal two unique types of transition paths, corresponding to either an arrest in the G1/S or G2/M phase, when cells undergo EMT. The existence of two paths agrees with our previous live cell imaging studies (Wang et al., Sci. Adv. 2020, 6:eaba9309; eLife 2022, 11:e74866), but not pseudotime analyses reported in the literature. Our analyses also reveal a surprising backward cell cycle propagation of cells arrested in G2/M to a G1/S attractor through mitotic skipping. We obtained similar results with a number of other EMT scRNA-seq data sets, then confirmed with live cell imaging using a A549-Vim/RFP-PCNA-EGFP cell line. Our results provide mechanistic understanding of how a cell makes the decision between EMT and cell cycle progression, and demonstrate the importance of analyzing single cell data in the formalism of dynamical systems (Xing, Phys. Biol. 2022, 19: 061001).

Cycle-Consistency-Based Uncertainty Quantification of Neural Networks in Inverse Imaging Problems

Uncertainty estimation is critical for numerous deep neural network (DNN) applications and has drawn increasing attention from researchers. In this study, we demonstrated an uncertainty quantification approach for DNNs used in inverse problems based on cycle consistency. We built forward–backward cycles using the available physical forward model and a trained DNN solving the inverse problem at hand and accordingly derived uncertainty estimators through regression analysis on the consistency of these forward–backward cycles. We theoretically analyzed the cycle consistency metrics and derived their relationship with the uncertainty, bias, and robustness of neural network inference. To demonstrate the effectiveness of these cycle-consistency-based uncertainty estimators, we classified corrupted and out-of-distribution input image data using widely used image deblurring and super-resolution neural networks as test beds. Our blind tests demonstrated that our method surpassed other models in detecting previously unseen data corruption and distribution shifts. This study provides a simple-to-implement and rapid uncertainty quantification method that can be universally applied to various neural networks used to solve inverse problems.

Distributed control of motor circuits for backward walking in Drosophila

How do descending inputs from the brain control leg motor circuits to change how an animal walks? Conceptually, descending neurons are thought to function either as command-type neurons, in which a single type of descending neuron exerts a high-level control to elicit a coordinated change in motor output, or through a population coding mechanism, whereby a group of neurons, each with local effects, act in combination to elicit a global motor response. The Drosophila Moonwalker Descending Neurons (MDNs), which alter leg motor circuit dynamics so that the fly walks backwards, exemplify the command-type mechanism. Here, we identify several dozen MDN target neurons within the leg motor circuits, and show that two of them mediate distinct and highly-specific changes in leg muscle activity during backward walking: LBL40 neurons provide the hindleg power stroke during stance phase; LUL130 neurons lift the legs at the end of stance to initiate swing. Through these two effector neurons, MDN directly controls both the stance and swing phases of the backward stepping cycle. These findings suggest that command-type descending neurons can also operate through the distributed control of local motor circuits.

TO COMPARE THE EFFECT OF FORWARD CYCLING VERSUS BACKWARD CYCLING ON PAIN FUNCTION AND RANGE OF MOTION IN SUBJECTS WITH KNEE OSTEOARTHRITIS – AN EXPERIMENTAL STUDY.

Background: Osteoarthritis is a chronic degenerative disease. The major symptom of Knee Osteoarthritis Are Pain Decreased Range of Motion and Functional impairment. The purpose of the study is to evaluate the effect of backward cycling and forward cycling in subject with Knee Osteoarthritis. The traditional protocol for treating knee osteoarthritis shows inability to treat the pain, function and range of motion at primary level of treatment. This can eradicate the drawback of generalized protocol. Method: The subject assessed thoroughly would be divided in three group. Group A would be given Conventional Treatment and Forward Cycling. Group B would be given Conventional Treatment and Backward Cycling. Group C would be given only Conventional Treatment. Treatment Duration for all three groups would be for 4 weeks. Then improvement would be evaluated in pain, Function and ROM by taking Post data. Then Pre-and Post data would be compared for final Conclusion. Conclusion: According to the present study the alternative hypothesis is accepted and null hypothesis is rejected. Which suggest that backward cycling proves to manage the symptoms efficiently than forward cycling and single handed conventional protocols.

Profiling analysts and actors in interaction: how behavioural aspects can positively affect the decision aid process

The behaviour of the actors in a decision aid process is determined by different factors, all of which have an impact on the effectiveness of the process and its results. A framework, originally created to document decision aid processes and to study the reasons for backward and forward cycles in the process, has been used to comparatively analyse several multi-criteria decision aid interventions. The study has led to the identification of three basic process typologies, in relation with some organisational and processual complexities and factors which, as behavioural aspects, have the main influence on the interaction between the analysts and actors of a decision aid process. The work is a proposal for the behavioral OR research agenda.

Cycle Completion Times Probe Interactions with Environment.

Recent measurements of the durations of nonequilibrium processes provide valuable information on microscopic mechanisms and energetics. Theory for corresponding experiments to date is well-developed for single-particle systems only. Little is known for interacting systems in nonequilibrium environments. Here we introduce and study a basic model for cycle processes interacting with an environment that can exhibit a net particle flow. We find a surprising richness of cycle time variations with environmental conditions. This manifests itself in unequal cycle times τ+ and τ- in forward and backward cycle directions with both asymmetries τ- < τ+ and τ- > τ+, speeding up of backward cycles by interactions, and dynamical phase transitions, where cycle times become multimodal functions of the bias. The model allows us to relate these effects to specific microscopic mechanisms, which can be helpful for interpreting experiments.

Functional-Consistent CycleGAN for CT to Iodine Perfusion Map Translation.

Image-to-image translation from a source to a target domain by means of generative adversarial neural network (GAN) has gained a lot of attention in the medical imaging field due to their capability to learn the mapping characteristics between different modalities. CycleGAN has been proposed for image-to-image translation with unpaired images by means of a cycle-consistency loss function, which is optimized to reduce the difference between the image reconstructed from the synthetically-generated domain and the original input. However, CycleGAN inherently implies that the mapping between both domains is invertible, i.e., given a mapping G (forward cycle) from domain A to B, there is a mapping F (backward cycle) that is the inverse of G. This is assumption is not always true. For example, when we want to learn functional activity from structural modalities. Although it is well-recognized the relation between structure and function in different physiological processes, the problem is not invertible as the original modality cannot be recovered from a given functional response. In this paper, we propose a functional-consistent CycleGAN that leverages the usage of a proxy structural image in a third domain, shared between source and target, to help the network learn fundamental characteristics while being cycle consistent. To demonstrate the strength of the proposed strategy, we present the application of our method to estimate iodine perfusion maps from contrast CT scans, and we compare the performance of this technique to a traditional CycleGAN framework.

A novel linear inertial piezoelectric actuator based on asymmetric clamping materials

Asymmetric inertial piezoelectric actuators are driven by the inertial impact difference between the forward and backward cycle. Typical ways to create inertial impact difference involve the application of asymmetric driving signals and clamping blocks with different dimensions. A new asymmetric inertial piezoelectric actuator using clamping blocks with asymmetric materials is proposed in this study. The block materials have different elastic modulus, which generate different inertial impact forces to drive the actuator. The relationship between the vibrator displacement and the elastic modulus difference of the clamping blocks are investigated by comparison of the FEM and theoretical results. A series of experiments are conducted to prove the feasibility of the proposed actuator. The actuator with steel-copper clamping materials achieves more stable working performance compared with other clamping materials, the minimum step displacement, repeatability parameter reaches 2.0 μm, 0.566 μm and 15.7 μm, 4.805 μm in non-resonant and resonant states under the signal of Vp-p = 15 V, respectively. The results show the proposed actuator works smoothly in both in non-resonant and resonant states, which provides a new reference for the application of inertial piezoelectric actuators.

Corticospinal excitability to the biceps and triceps brachii during forward and backward arm cycling is direction- and phase-dependent.

The purpose of this study was to evaluate corticospinal excitability to the biceps and triceps brachii during forward (FWD) and backward (BWD) arm cycling. Corticospinal and spinal excitability were assessed using transcranial magnetic stimulation and transmastoid electrical stimulation to elicit motor evoked potentials (MEPs) and cervicomedullary evoked potentials (CMEPs), respectively. MEPs and CMEPs were recorded from the biceps and triceps brachii during FWD and BWD arm cycling at 2 positions, 6 and 12 o'clock. The 6 o'clock position corresponded to mid-elbow flexion and extension during FWD and BWD cycling, respectively, while 12 o'clock corresponded to mid-elbow extension and flexion during FWD and BWD cycling, respectively. During the flexion phase, MEP and CMEP amplitudes of the biceps brachii were higher during FWD cycling. However, during the extension phase, MEP and CMEP amplitudes were higher during BWD cycling. For the triceps brachii, MEP amplitudes were higher during FWD cycling regardless of phase. However, CMEP amplitudes were phase-dependent. During the flexion phase, CMEPs of the triceps brachii were higher during FWD cycling compared with BWD, but during the extension phase CMEPs were higher during BWD cycling compared with FWD. The data suggest that corticospinal and spinal excitability to the biceps brachii is phase- and direction-dependent. In the triceps brachii, spinal, but not corticospinal, excitability is phase-dependent when comparing FWD and BWD cycling. Novelty This is the first study to assess corticospinal excitability during FWD and BWD locomotor output. Corticospinal excitability during arm cycling depends on the direction, phase, and muscle being assessed.

Corticospinal and Spinal Excitability to the Biceps and Triceps Brachii is Modulated Differently between Forward and Backward Arm Cycling

The purpose of this study was to evaluate supraspinal and spinal excitability to the biceps and triceps brachii when comparing forward (FWD) and backward (BWD) arm cycling. Supraspinal and spinal excitability were assessed non‐invasively using transcranial magnetic stimulation (TMS) to elicit motor evoked potentials (MEPs) and transmastoid electrical stimulation (TMES) to elicit cervicomedullary evoked potentials (CMEPs), respectively. MEPs and CMEPs were recorded from the biceps and triceps brachii during FWD and BWD arm cycling at two positions, the 6 and 12 o'clock position. The 6 o'clock position corresponded to mid elbow flexion and extension during FWD and BWD cycling, respectively, while the 12 o'clock position corresponded to mid elbow extension and flexion during FWD and BWD cycling, respectively. Participants completed four arm cycling trials, two FWD and two BWD, at 60 rpm and 25 W. During the flexion phase MEP (p = .001) and CMEP (p = .001) amplitudes of the biceps brachii were higher during FWD cycling. However, during the extension phase MEP (p = .006) and CMEP (p = .003) amplitudes were higher during BWD cycling. For the triceps brachii MEP amplitudes were higher during FWD cycling compared to BWD (p = .027) regardless of the functional phase (flexion vs. extension) of the movement cycle. However, spinal excitability to the triceps brachii was dependent on the functional phase of the movement cycle. During the flexion phase CMEPs of the triceps brachii were higher during FWD cycling compared to BWD (p = .032), but during the extension phase CMEPs were higher during BWD cycling compared to FWD (p = .001). This data suggests that the modulation of CSE and spinal excitability to the biceps brachii is dependent on the functional phase of the movement cycle and on the cycling direction. Also, spinal excitability but not CSE to the triceps brachii is dependent on the functional phase of the movement cycle when comparing FWD and BWD cycling.Support or Funding InformationNSERC Discovery Grant awarded to K.E. PowerThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Four-Component Catalytic Machinery: Reversible Three-State Control of Organocatalysis by Walking Back and Forth on a Track.

A three-component supramolecular walker system is presented where a two-footed ligand (biped) walks back and forth on a tetrahedral 3D track upon the addition and removal of copper(I) ions, respectively. The addition of N-methylpyrrolidine as a catalyst to the walker system generates a four-component catalytic machinery, which acts as a three-state switchable catalytic ensemble in the presence of substrates for a conjugate addition. The copper(I)-ion-initiated walking process of the biped ligand on the track regulates the catalytic activity in three steps: ON versus intON (intermediate ON) versus OFF. To establish the operation of the four-component catalytic machinery in a mixture of all constituents, forward and backward cycles were performed in situ illustrating that both the walking process and catalytic action are fully reversible and reproducible.

Cycle symmetry, limit theorems, and fluctuation theorems for diffusion processes on the circle

Cyclic structure and dynamics are of great interest in both the fields of stochastic processes and nonequilibrium statistical physics. In this paper, we find a new symmetry of the Brownian motion named as the quasi-time-reversal invariance. It turns out that such an invariance of the Brownian motion is the key to prove the cycle symmetry for diffusion processes on the circle, which says that the distributions of the forming times of the forward and backward cycles, given that the corresponding cycle is formed earlier than the other, are exactly the same. With the aid of the cycle symmetry, we prove the strong law of large numbers, functional central limit theorem, and large deviation principle for the sample circulations and net circulations of diffusion processes on the circle. The cycle symmetry is further applied to obtain various types of fluctuation theorems for the sample circulations, net circulation, and entropy production rate.

A stochastic automaton model for simulating kinesin processivity.

Cellular interactions of kinesin-1, an adenosine triphosphate (ATP)-driven motor protein capable of undergoing multiple steps on a microtubule (MT), affect its mechanical processivity, the number of steps taken per encounter with MT. Even though the processivity of kinesin has been widely studied, a detailed study of the factors that affect the stepping of the motor along MT is still lacking. We model the cellular interactions of kinesin as a probabilistic timed automaton and use the model to simulate the mechanical processivity of the motor. Theoretical analysis suggests: (i) backward stepping tends to be powered by ATP hydrolysis, rather than ATP synthesis, (ii) backward stepping powered by ATP synthesis is more likely to happen with limiting ATP concentration ([ATP]) at high loads and (iii) with increasing load the frequency of backward stepping powered by ATP hydrolysis at high [ATP] is greater than that powered by ATP synthesis at limiting [ATP]. Together, the higher frequency of backward stepping powered by ATP hydrolysis than by ATP synthesis is found to be a reason for the more dramatic falling of kinesin processivity with rising load at high [ATP] compared with that at low [ATP]. Simulation results further show that the processivity of kinesin can be determined by the number of ATP hydrolysis and synthesis kinetic cycles taken by the motor before becoming inactive. It is also found that the duration of a backward stepping cycle at high loads is more likely to be less than that of a forward stepping cycle. h.r.khataee@griffithuni.edu.au or a.liew@griffith.edu.au.

An Efficient Parallel Algorithm for Large Scale Hydrothermal System Operation Planning

This paper presents an efficient parallel algorithm applied to the problem of large scale hydrothermal system operation planning. This problem is solved by stochastic dual dynamic programming. A plan of operation is determined for each stage of the planning period with the objective of minimizing the expected cost of operation over the planning horizon. For each state, the hydrothermal operation problem is modeled as a linear programming problem and the dual variables associated with the solution are used to construct the Benders cuts. The plan of operation is represented by the future cost function, which is approximated by a piecewise linear function, constructed iteratively by the Benders cuts. An optimized parallelization strategy is applied to both the forward and backward cycles of the dynamic programming convergence process with very high parallel efficiency. For a planning horizon of 5 years and 200 inflow scenarios for each reservoir, the sequential solution for the Brazilian system requires almost 15 hours of processing time. The parallel algorithm obtains exactly the same solution in less than 23 min on 64 cores and in less than 17 min on 128 cores.

Context-Dependent Modulation of Cutaneous Reflex Amplitudes during Forward and Backward Leg Cycling

We used amplitude modulation of cutaneous reflexes during leg cycling as a paradigm to investigate neural control mechanisms regulating forward (FWD) and backward (BWD) rhythmic limb movement. Our prediction was a simple reversal of reflex modulation during BWD leg cycling and context-dependent reflex modulation. Cutaneous reflexes were evoked by electrical stimulation delivered to the superficial peroneal (SP) and distal tibial (TIB) nerves at the ankle. EMG recordings were collected from muscles acting at the hip, knee, and ankle. Kinematic data were also collected at these joints. Cutaneous reflexes were analyzed according to the phase of movement in which they were evoked. When functional phases (i.e., flexion or extension) of cycling were matched between FWD and BWD, background EMG and reflex modulation patterns were generally similar. The reflex patterns when compared at similar functional phases presented as a simple reversal suggesting FWD and BWD cycling are regulated by similar neural mechanisms. The general reflex regulation of limb trajectory was maintained between cycling directions in accordance with the task requirements of the movement direction.

Sisyphus cooling and amplification by a superconducting qubit

A superconducting qubit—a mesoscopic structure that behaves like a quantum two-level system—has been used to change the temperature of a resonant circuit, in close analogy to the so-called Sisyphus cooling and amplification protocols used in laser cooling of atoms. Laser cooling of atoms paved the way for remarkable achievements in quantum optics, including Bose–Einstein condensation and trapping in optical lattices. Recently, superconducting qubits—micrometre-size superconducting circuits—were shown to act as artificial atoms, exhibiting quantum effects such as Rabi oscillations and Ramsey fringes1,2,3. Coupling superconducting circuits to resonators brought them into the realm of quantum electrodynamics4,5,6,7 and opened up perspectives for using them as micro-coolers or to create a population inversion inducing lasing behaviour8,9,10,11,12. Here, we demonstrate so-called Sisyphus cooling13 and amplification of an LC resonator, which consists of an inductor L and a capacitor C, by a superconducting qubit, furthering the analogies between optical and circuit quantum electrodynamics. In quantum optics, the motion of the atom is cooled or amplified by a laser driving its electronic degrees of freedom. In our system, the roles of the two degrees of freedom are played by the levels of the resonator and the qubit. Red-detuned high-frequency driving of the qubit produces cooling, because the low-frequency LC circuit carries out work in the forward and backward oscillation cycle, always increasing the energy of the qubit. For blue-detuning, the same mechanism leads to Sisyphus amplification and a precursor of lasing. Parallel to the experimental demonstration, we analyse these processes theoretically, quantitatively confirming our interpretation.

High temperature sequestration of CO2 using lithium zirconates

Abstract Equilibrium and kinetics of CO2 reaction with lithium zirconates synthesised by two different methods are reported. Considerably faster rates of high temperature reaction were obtained for the new material synthesised by a soft-chemistry route without the use of alkaline metal dopants, in comparison with the available literature data, with the highest rate 0.83 wt% min−1. Lithium zirconate was found to be stable in consecutive forward–backward reaction cycles. Reaction rate dependency on the partial CO2 pressure was examined. The apparent slow reaction rates at p C O 2 0.4 bar are due to mass transfer limitations. Detailed analysis of the reverse reaction of decomposition of lithium carbonate–zirconia mixed matrix revealed complex three-step behaviour, which was associated with the transition from reaction to mass transfer control. The latter was successfully eliminated in the material prepared from a high surface area zirconia precursor. Low temperature interaction between lithium zirconate and CO2 revealed during experiments performed at 25–550 °C is also discussed.