Concurrent Adaptation Research Articles

The Additional Effect of Training Above the Maximal Metabolic Steady State on VO2peak, Wpeak and Time-Trial Performance in Endurance-Trained Athletes: A Systematic Review, Meta-analysis, and Reality Check.

To improve sport performance, athletes use training regimens that include exercise below and above the maximal metabolic steady state (MMSS). The objective of this review was to determine the additional effect of training above MMSS on VO2peak, Wpeak and time-trial (TT) performance in endurance-trained athletes. Studies were included in the review if they (i) were published in academic journals, (ii) were in English, (iii) were prospective, (iv) included trained participants, (v) had an intervention group that contained training above and below MMSS, (vi) had a comparator group that only performed training below MMSS, and (vii) reported results for VO2peak, Wpeak, or TT performance. Medline and SPORTDiscus were searched from inception until February 23, 2023. Fourteen studies that ranged from 2 to 12weeks were included in the review. There were 171 recreational and 128 competitive endurance athletes. The mean age and VO2peak of participants ranged from 15 to 43years and 38 to 68mL·kg-1·min-1, respectively. The inclusion of training above MMSS led to a 2.5mL·kg-1·min-1 (95% CI 1.4-3.6; p < 0.01; I2 = 0%) greater improvement in VO2peak. A minimum of 81 participants per group would be required to obtain sufficient power to determine a significant effect (SMD 0.44) for VO2peak. No intensity-specific effect was observed for Wpeak or TT performance, in part due to a smaller sample size. A single training meso-cycle that includes training above MMSS can improve VO2peak in endurance-trained athletes more than training only below MMSS. However, we do not have sufficient evidence to conclude that concurrent adaptation occurs for Wpeak or TT performance.

Stakeholder perceptions on climate change impacts and adaptation actions in Greece

The scientific evidence clearly demonstrates that human activity plays a significant role in the changes to the world's climate, and it is crucial to take adaptive actions to mitigate the impacts of these changes. Effective climate adaptation requires raising awareness among a variety of key stakeholders, such as executives and staff in the public and private sectors, while assessing the incentives and actions they undertake and allowing them to act at various levels of engagement, ranging from global to local. The aim of this study was to investigate the levels of awareness, perceived values, recommendations and expectations regarding climate change among key actors in Greece, focusing on the consequences of climate change in the country and the concurrent adaptation actions taken by stakeholders. A web-based survey was designed and conducted, and responses were systematically collected, categorized and analyzed. The key stakeholders believed that planning and implementing adaptation measures are crucial in addressing and minimizing the impacts of climate change. However, it was also noted that these plans and measures alone are insufficient to counteract the long-term, devastating consequences of climate change in Greece, and more comprehensive and targeted measures must be adopted. It was also concluded that the main obstacle to addressing and adapting to climate change in terms of public policy planning in Greece is the lack of human and financial resources, particularly among public institutions.

Recordings of Twentieth Century Serbian Church Chant

This paper discusses representative examples of audio recordings of traditional Serbian church chant, an important testimony to Orthodox Serbian cultural and spiritual heritage, as well as the characteristics of this oral musical tradition in the twentieth century. My focus lies not only on the most important published audio recordings, but also on the collection of the unpublished audio recordings from the field work on the wide territory of Serbian cultural space, that is: in Serbia, Dalmatia, Bosnia and Herzegovina and Hungary during the last three decades of the twentieth century. All of the examples mentioned in the text represent traditional Serbian church chant in its original, unison version, sometimes also as two-part singing. Taking into account the ethnological and anthropological perception of the multi-generational transmission and concurrent adaptation to the cultural, historical and societal changes, as well as the link between the heritage and the cultural uniqueness of its creators and carriers, these recordings were approached as the authentic trace of a live tradition, and a key to the assessment, study and preservation of the Serbian church chant, as an element of the intangible cultural heritage.

Assessment of existing structures under climate change

Assessment of the influence of human activities on recent, current, and future global and regional climate conditions and extremes has advanced sufficiently to provide a reasonable measure of its impact across the globe. The lack of concurrent adaptation of the design base for load bearing structures results mainly from the absence of a clear signal that climate change will have a significant effect on the climate actions that are accounted for in the structural design basis. The recent IPCC assessment of the physical science basis of climate change reports significant advances in observing and projecting changes in weather and climate extremes due to human influences. This provides an opportunity to reassess projections of future climate action conditions. Whilst the IPCC assessment confirms previous indications that, for example extreme wind will respond moderately globally, improvements in understanding and projecting changes show that trends will be overshadowed by uncertainties. The implication is that the design base will need to account for increasing uncertainties as climate actions are projected into the future, over the service life of existing structures, as well as those designed to current standards. The design base consequently in advance need to reflect continuous changes of existing structures.

Fractal mathematical over extended finite fields Fp[x]/(f(x))

In this paper, we have defined an algorithm for the construction of iterative operations, based on dimensional projections and correspondence between the properties of extended fields, with respect to modular reduction. For a field with product operations R(x) ⊗ D(x), over finite fields, GF[(pm)n−k]. With Gp[x]/(g(f(x)), whence the coefficient of the g(x) is replaced after a modular reduction operation, with characteristic p. Thus, the reduced coefficients of the generating polynomial of G contain embedded the modular reduction and thus simplify operations that contain basic finite fields. The algorithm describes the process of construction of the GF multiplier, it can start at any stage of LFSR; it is shift the sequence of operation, from this point on, thanks to the concurrent adaptation, to optimize the energy consumption of the GF iterative multiplier circuit, we can claim that this method is more efficient. From this, it was realized the mathematical formalization of the characteristics of the iterative operations on the extended finite fields has been developed, we are applying a algorithm several times over the coefficients in the smaller field and then in the extended field, concurrent form.

Rapid differentiation of plasticity in life history and morphology during invasive range expansion and concurrent local adaptation in the horned beetle Onthophagus taurus.

Understanding the interplay between genetic differentiation, ancestral plasticity, and the evolution of plasticity during adaptation to environmental variation is critical to predict populations' responses to environmental change. However, the role of plasticity in rapid adaptation in nature remains poorly understood. We here use the invasion of the horned beetle Onthophagus taurus in the United States during the last half century to study the contribution of ancestral plasticity and post-invasion evolution of plastic responses in rapid population differentiation. We document latitudinal variation in life history and morphology, including genetic compensation in development time and body size, likely adaptive responses to seasonal constraints in the North. However, clinal variation in development time and size was strongly dependent on rearing temperature, suggesting that population differentiation in plasticity played a critical role in successful adaptation on ecological timescales. Clinal variation in wing shape was independent of ancestral plasticity, but correlated with derived plasticity, consistent with evolutionary interdependence. In contrast, clinal variation in tibia shape aligned poorly with thermal plasticity. Overall, this study suggests that post-invasion evolution of plasticity contributed to range expansions and concurrent adaptation to novel climatic conditions.

A 0.1-pJ/b/dB 1.62-to-10.8-Gb/s Video Interface Receiver With Jointly Adaptive CTLE and DFE Using Biased Data-Level Reference

In this article, a 1.62-to-10.8-Gb/s video interface receiver with jointly adaptive equalization is presented. Sign–sign least-mean-squares (SSLMS) algorithm is applied to adaptation for not only a decision feedback equalizer (DFE) but also a continuous-time linear equalizer (CTLE) to unify the adaptation methods. This approach facilitates concurrent adaptation that results in short adaptation time and also reduces the extra hardware and power consumption. An average value of fourth- and fifth-post-cursors is used as an indicator for CTLE adaptation, and the validity is substantiated by numerical analysis and simulation. Furthermore, the concept of a biased data-level reference (dLev) is proposed and analyzed to alleviate insufficient adaptation of the SSLMS algorithm in the presence of pre-cursor inter-symbol interference (ISI). The proposed dLev is acquired by simply adjusting up and down ratios of the dLev update equation. The prototype test chip is implemented in 65-nm CMOS technology and occupies an active area of 0.174 mm2. The proposed adaptive equalizers compensate for the channel loss of up to 34 dB at 10.8 Gb/s. Total power consumption of the receiver is 37.2 mW at 10.8 Gb/s, and the figure of merit (energy efficiency per channel loss at Nyquist frequency) of 0.1 pJ/b/dB is achieved.

Role of muscle coactivation in adaptation of standing posture during arm reaching.

The ability to maintain stable, upright standing in the face of perturbations is a critical component of daily life. A common strategy for resisting perturbations and maintaining stability is muscle coactivation. Although arm muscle coactivation is often used during adaptation of seated reaching movements, little is known about postural muscle activation during concurrent adaptation of arm and standing posture to novel perturbations. In this study we investigate whether coactivation strategies are employed during adaptation of standing postural control, and how these strategies are prioritized for adaptation of standing posture and arm reaching, in two different postural stability conditions. Healthy adults practiced planar reaching movements while grasping the handle of a robotic arm and standing on a force plate; the robotic arm generated a velocity-dependent force field that created novel perturbations in the forward (more stable) or backward (less stable) direction. Surprisingly, the degree of arm and postural adaptation was not influenced by stability, with similar adaptation observed between conditions in the control of both arm movement and standing posture. We found that an early coactivation strategy can be used in postural adaptation, similar to what is observed in adaptation of arm reaching movements. However, the emergence of a coactivation strategy was dependent on perturbation direction. Despite similar adaptation in both directions, postural coactivation was largely specific to forward perturbations. Backward perturbations led to less coactivation and less modulation of postural muscle activity. These findings provide insight into how postural stability can affect prioritization of postural control objectives and movement adaptation strategies.NEW & NOTEWORTHY Muscle coactivation is a key strategy for modulating movement stability; this is centrally important in the control of standing posture. Our study investigates the little-known role of coactivation in adaptation of whole body standing postural control. We demonstrate that an early coactivation strategy can be used in postural adaptation, but muscle activation strategies may differ depending on postural stability conditions.

Metapsychological consequences of the conscious brainstem: A critique of the conscious id

ABSTRACTIn this article, the thesis that the id is conscious [Solms, (2013a) The conscious id. Neuropsychoanalysis, 15(1), 5–19] is scrutinized by carving out a crucial implicit assumption on which the argument relies. The validity of this assumption is then assessed in two ways: first by an analysis of Freud’s description of the relation between the mental apparatus and the brain, second by analyzing the neuropsychoanalytical implications of the Mealy machine [Mealy, 1955. A method for synthesizing sequential circuits. Bell Labs Technical Journal, 34(5), 1045–1079] – a mathematical model that is used to describe the relation between the software and hardware of computers. The result of my assessment is that Solms’s implicit assumption faces serious objections and therefore the conclusion that the id is conscious cannot be upheld. In the remaining article I develop, based on the neuroscientific findings on which Solms developed his thesis [Solms & Panksepp, 2012. The “id” knows more than the “ego” admits: Neuropsychoanalytic and primal consciousness perspectives on the interface between affective and cognitive neuroscience. Brain Sciences, 2(2), 147–175], a concurrent adaptation of the structural model. This is achieved by an analysis of Freud's development of his metapsychological theory from 1899 to 1923, with a strong focus on the conceptualization of consciousness that underwent, as I shall work out, a major change. The result is a new metapsychological model that, so I claim, gets rid of a crucial weak spot of the structural model [Freud, 1923. The ego and the id. Standard Edition, 19, 12–59] and allows the integration of different neuropsychological theories.

Flexible and Efficient Decision-Making for Proactive Latency-Aware Self-Adaptation

Proactive latency-aware adaptation is an approach for self-adaptive systems that considers both the current and anticipated adaptation needs when making adaptation decisions, taking into account the latency of the available adaptation tactics. Since this is a problem of selecting adaptation actions in the context of the probabilistic behavior of the environment, Markov decision processes (MDPs) are a suitable approach. However, given all the possible interactions between the different and possibly concurrent adaptation tactics, the system, and the environment, constructing the MDP is a complex task. Probabilistic model checking has been used to deal with this problem, but it requires constructing the MDP every time an adaptation decision is made to incorporate the latest predictions of the environment behavior. In this article, we describe PLA-SDP, an approach that eliminates that runtime overhead by constructing most of the MDP offline. At runtime, the adaptation decision is made by solving the MDP through stochastic dynamic programming, weaving in the environment model as the solution is computed. We also present extensions that support different notions of utility, such as maximizing reward gain subject to the satisfaction of a probabilistic constraint, making PLA-SDP applicable to systems with different kinds of adaptation goals.

Context-dependent concurrent adaptation to static and moving targets.

Is the neural control of movements towards moving targets independent to that of static targets? In the following experiments, we used a visuomotor rotation adaptation paradigm to examine the extent to which adapting arm movements to static targets generalize to that of moving targets (i.e. pursuit or tracking). In the first and second experiments, we showed that adaptation to perturbed tracking movements generalizes to reaching movements; reach aftereffects following perturbed tracking were about half the size (≈9°) of those produced following reach training (≈ 19°). Given these findings, in the final experiment we associated opposing perturbations (-30° and +30°) with either reaching or tracking movements and presented them within the same experimental block to determine whether these contexts allow for dual adaptation. We found that the group that experienced opposing perturbations was able to reduce both reaching and tracking errors, as well as produce reach aftereffects following dual training of ≈7°, which were substantially smaller than those produced when reach training was not concurrent with tracking training. This reduction in reach aftereffects is consistent with the extent of the interference from tracking training as measured by the reach aftereffects produced when only that condition was performed. These results suggest partial, but not complete, overlap in the learning processes involved in the acquisition of tracking and reaching movements.

T021 Synaptic plasticity mechanism explains the specificity of direct current stimulation

Abstract Long term effects of transcranial electric stimulation with direct currents (tDCS) have been often attributed to synaptic plasticity. A number of human and animal studies provide support for this hypothesis. However, the exact mechanisms by which direct current stimulation affects synaptic plasticity remain unclear. Here we will present data on long term potentiation (LTP) and long term depression (LTD) of synaptic efficacy – the presumed cellular mechanism of learning. The experiments leverage classic plasticity induction protocols in hippocampal rodent brain slices (high frequency pulses, low frequency pulses, and theta burst stimulation). The main finding is that direct current stimulation in isolation does not affect synaptic efficacy. Only when stimulation is paired with one of these induction protocols do we observe effects on synaptic efficacy. The effects vanish in the presence of NMDA receptor blockers. The polarity of the effect depends on the induction mechanism and the site of plasticity, suggesting that the local polarization of the cellular membrane is the mediating factor. Based on these data we propose that tDCS in human experiments is task specific, not because of the exact placement of electrodes, but because stimulation only affects those synapses that are already undergoing plasticity. We predict that the most specific and effective tDCS interventions will be those that pair stimulation with a concurrent adaptation or learning protocol.

Correction to “Concurrent Adaptation of Human and Machine Improves Simultaneous and Proportional Myoelectric Control” [Jul 15 618-627

In the above-named work [ibid., vol. 23, no. 4, pp. 618–627, Jul. 2015], the affiliation for Klaus-Robert Mueller should have appeared as follows: K-R. Mueller is with the Machine Learning Laboratory, Berlin Institute of Technology, D-10587 Berlin, Germany, and also with the Bernstein Center for Computational Neuroscience (BCCN), D-10587 Berlin, Germany, and also with the Department of Brain and Cognitive Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713, Korea; (e-mail: klaus-robert.mueller@tu-berlin.de).

Hue Selectivity in Human Visual Cortex Revealed by Functional Magnetic Resonance Imaging.

The variability of color-selective neurons in human visual cortex is considered more diverse than cone-opponent mechanisms. We addressed this issue by deriving histograms of hue-selective voxels measured using fMRI with a novel stimulation paradigm, where the stimulus hue changed continuously. Despite the large between-subject difference in hue-selective histograms, individual voxels exhibited selectivity for intermediate hues, such as purple, cyan, and orange, in addition to those along cone-opponent axes. In order to rule the possibility out that the selectivity for intermediate hues emerged through spatial summation of activities of neurons selectively responding to cone-opponent signals, we further tested hue-selective adaptations in intermediate directions of cone-opponent axes, by measuring responses to 4 diagonal hues during concurrent adaptation to 1 of the 4 hues. The selective and unidirectional reduction in response to the adapted hue lends supports to our argument that cortical neurons respond selectively to intermediate hues.

Concurrent adaptation to opposing visuomotor rotations by varying hand and body postures.

When reaching towards objects, the human central nervous system (CNS) can actively compensate for two different perturbations simultaneously (dual adaptation), though this does not simply occur upon presentation. Dual adaptation is made more difficult when the desired trajectories and targets are identical and hence do not cue the impending perturbation. In cases like these, the CNS requires contextual cues in order to predict the dynamics of the environment. Not all cues are effective at facilitating dual adaptation. In two experiments, we investigated the efficacy of two contextual cues that are intrinsic to the CNS, namely hand as well as body posture in concurrently adapting to two opposing visuomotor rotations. For the hand posture experiment, we also look at the role of extended training. Participants reached manually to visual targets with their unseen hand represented by a cursor that was rotated either 30° clockwise or counterclockwise, determined randomly on each reach. Each rotation was associated with a distinct hand posture (a precision or power grip, respectively) in one experiment and a distinct body rotation (10° leftward or rightward turn of the seat, respectively, while fixating straight) in the second experiment. Critically, the targets (and thus, the required cursor trajectories) were identical in both rotations. We found that how people held the tool or oriented their body while reaching is sufficient for concurrently adapting separate visuomotor mappings such that over time, reach errors significantly decrease. Extended practice did not lead to further benefits though. These findings suggest that when the required cursor movements are identical for different visuomotor mappings, dual adaptation is still possible given sufficient intrinsic contextual cues.

Concurrent Adaptation of Human and Machine Improves Simultaneous and Proportional Myoelectric Control.

Myoelectric control of a prosthetic hand with more than one degree of freedom (DoF) is challenging, and clinically available techniques require a sequential actuation of the DoFs. Simultaneous and proportional control of multiple DoFs is possible with regression-based approaches allowing for fluent and natural movements. Conventionally, the regressor is calibrated in an open-loop with training based on recorded data and the performance is evaluated subsequently. For individuals with amputation or congenital limb-deficiency who need to (re)learn how to generate suitable muscle contractions, this open-loop process may not be effective. We present a closed-loop real-time learning scheme in which both the user and the machine learn simultaneously to follow a common target. Experiments with ten able-bodied individuals show that this co-adaptive closed-loop learning strategy leads to significant performance improvements compared to a conventional open-loop training paradigm. Importantly, co-adaptive learning allowed two individuals with congenital deficiencies to perform simultaneous 2-D proportional control at levels comparable to the able-bodied individuals, despite having to a learn completely new and unfamiliar mapping from muscle activity to movement trajectories. To our knowledge, this is the first study which investigates man-machine co-adaptation for regression-based myoelectric control. The proposed training strategy has the potential to improve myographic prosthetic control in clinically relevant settings.

Characterizing the effects of multidirectional motion adaptation.

Recent sensory experience can alter our perception and change the response characteristics of sensory neurons. These effects of sensory adaptation are a ubiquitous property of perceptual systems and are believed to be of fundamental importance to sensory coding. Yet we know little about how adaptation to stimulus ensembles affects our perception of the environment as most psychophysical experiments employ adaptation protocols that focus on prolonged exposure to a single visual attribute. Here, we investigate how concurrent adaptation to multiple directions of motion affects perception of subsequently presented motion using the direction aftereffect. In different conditions, observers adapted to a stimulus ensemble comprised of dot directions sampled from different distributions or to bidirectional motion. Increasing the variance of normally distributed directions reduced the magnitude of the peak direction aftereffect and broadened its tuning profile. Sampling of asymmetric Gaussian and uniform distributions resulted in shifts of direction aftereffect tuning profiles consistent with changes in the perceived global direction of the adapting stimulus. Adding dots in a direction opposite or orthogonal to a unidirectional adapting stimulus led to a pronounced reduction in the direction aftereffect. A simple population-coding model, in which adaptation selectively alters the responsivity of direction-selective neurons, can accommodate the effects of multidirectional adaptation on the perceived direction of motion.

Performance monitoring in realistic environments: can translating neuroscientific insights augment real-world behavioral adaptation?

To exert successful goal-directed behaviors, humans must continually monitor their actions for deviations from their intended outcomes. If a mismatch between the intended and actual outcome of an action is detected, performance monitoring enables the concurrent adaptation of ongoing behavior. One

Concurrent Directional Adaptation of Reactive Saccades and Hand Movements to Target Displacements of Different Size

ABSTRACTWhen eye and hand movements are concurrently aimed at double-step targets that call for equal and opposite changes of response direction (–10° for the eyes, +10° for the hand), adaptive recalibration of both motor systems is strongly attenuated; instead, hand but not eye movements are changed by corrective strategies (V. Grigorova et al., 2013a). The authors introduce a complementary paradigm, where double-step targets call for a –10° change of eye and a −30° change for hand movements. If compared to control subjects adapting only the eyes or only the hand, adaptive improvements were comparable for the eyes but were twice as large for the hand; in contrast, eye and hand aftereffects were comparable to those in control subjects. The authors concluded that concurrent exposure of eyes and hand to steps of the same direction but different size facilitated hand strategies, but didn't affect recalibration. This finding together with previous one (V. Grigorova et al., 2013a), suggests that concurrent adaptation of eyes and hand reveals different mechanisms of recalibration for step sign and step size, which are shared by reactive saccades and hand movements. However, hand mostly benefits from strategies provoked by the difference in target step sign and size.

Comparative physiology and hyperuricemia as a causal factor for hypertension

Recently, Johnson et al. eloquently discussed the survival advantage of loss of uricase leading to relative hyperuricemia, about 5 mg/dl, in hominoids ((1)) in comparison to other mammals such as rats and dogs, with uric acid levels at 1 mg/dl or less ((2, 3)). Multiple studies, notably by Dr. Johnson's group have demonstrated that associations between serum uric acid levels and blood pressure are linear and robust, both in rats and humans. Moreover, supporting causality, inhibiting uricase with oxonic acid increases uric acid levels prior to an increase of blood pressure in rats ((2)). However, the highest serum levels of uric acid achieved in rats after oxonic acid ((2)) are still much lower than those observed in normotensive humans. Most primates are not hypertensive, and freely moving laboratory rats, dogs, and healthy humans at recommended salt intake show similar mean arterial pressure. Thus, loss of uricase in hominoid evolution must have been accompanied by a concurrent adaptation that allowed hominoids to maintain much higher uric acid levels at normal blood pressure. This evolutionary adaptation to loss of uricase is unknown but is probably intracellular because to induce cell activation rat vascular smooth muscle cells need relatively low concentrations of uric acid (2.5 mg/dl) ((4)), whereas human vascular endothelial and smooth muscle cells require at least twice as much (6 mg/dl) ((5)). In the light of these observations the obvious question is the nature of the unidentified intracellular adaptation that allowed hominoids evolutionary survival at normal blood pressure despite the loss of uricase.