Monthly Archives: January 2017

Consistency Of Task Outcome And The Degrees Of Freedom Problem-The Brain Is Potentially Not A Micro-Manager When Providing Solutions To Complex Problems

Part of the reason I enjoy cycling as my chosen sport now I am older is not just because it is beneficial from a health perspective, but because the apparent regularity of the rhythmical circular movement required for pedalling creates a sense of peace in me and paradoxically allows my mind to wander a bit away from its routine and usually work-focussed and life task orientated thoughts. I enjoy watching competitive darts, from the perspective of marvelling at how the folk participating in the competitions seem to so often hit the small area of the board they are aiming for with such precision, after fairly rapidly throwing their darts when it is their turn to do so. This week an old colleague and friend from University of Cape Town days, Dr Angus Hunter, published some interesting work on how the brain controls muscle activity during different experimental conditions, a field of which he is a world expert in, and it was great to read about his new research and innovative ideas as always. Some of the most fun times of my research career were spent in the laboratory working with Angus measuring muscle activity during movement related tasks, where one of our most challenging issues to deal with was the variability of the signal our testing devices recorded when measuring either the power output from, or electrical activity in, muscle fibres each time they contracted when a trial participant was asked to do the same task. A large part of the issue we had to solve then was whether this was signal ‘noise’ and an artefact of our testing procedures, or if it was part of the actual recruitment strategy the brain used to control the power output from the muscles. All of these got me thinking about motor control mechanisms, and how movement and activity is regulated in a way that gets tasks done in a seemingly smooth and co-ordinated way, often without us having to think about what we are doing, while when one measures individual muscle function it is actually very ‘noisy’ and variable, even during tasks which are performed with a high degree of accuracy, and how the brain either creates or ‘manages’ this variability and ‘noise’ to generate smooth and accurate rhythmical or target-focussed activity, as that which occurs when cycling and throwing darts respectively.

Some of the most interesting scientific work that I have ever read about was done by Nikolai Bernstein, a Russian neurophysiologist, who when working in the 1920’s at the somewhat euphemistically named Moscow Central Institute of Labour, examined motor control mechanisms during movement. As part of the communist government of the times centrally driven plans to improve worker productivity and output, Bernstein did research on manual labour tasks such as hammering and cutting, in order to try and understand how to optimise it. Using novel ‘cyclogram’ photography techniques, where multiple pictures were taken of a worker using a hammer or chisel to which a light source had been attached, he was able to produce the astonishing observation that each time the worker hit a nail or cut through metal, their arm movements were not identical each time they performed the action, and rather that there was a great degree of variability each time the similar action was performed, even though usually this variability in action produced an outcome which had a high degree of accuracy. He realized that each complete movement, such as moving the arm towards the target, is made up of a number of smaller movements of muscles around the shoulder, elbow and wrist joints, which together synergistically create the overall movement. Given how many muscles there are in the arm, working around three joints (and potentially more when one thinks of the finger joints and muscles controlling them), he suggested that were a very large number of potential combinations of muscle actions and joint positions that could be used for the same required action, and a different combination of these appeared to be ‘chosen’ by the brain each time it performed a repetitive task. From a motor control perspective, Bernstein deduced that this could potentially cause a problem for the brain, and whatever decision-making process decided on which movement pattern it would use to complete a task, given that it created a requirement for choosing a particular set of muscle synergies from a huge number of different options available, or in contrast not choosing all the other muscle synergistic options, each time the individual was required to perform a single task or continue performing a repetitive task. This would require a great amount of calculation and decision-making capacity on a repetitive basis by the brain / control processes, and he called this the motor redundancy, or degrees of freedom, problem.

Like a lot of work performed in the Stalin era in Russia, his fascinating work and observations did not become known to Western scientists until the 1960’s, when he published a text-book of his career in science, which was subsequently translated and taken forward by excellent contemporary movement control scientists like Mark Latash of the University of Pennsylvania State in the USA. Further studies have supported Bernstein’s earlier work, and it is astonishing how much variability there is in each movement trajectory of a complex action that is goal orientated. Mark has suggested that this is not a redundancy problem, but rather one of abundancy, with the multiple choices available being of benefit to the body of any individual performing repetitive tasks, potentially from a fatigue resistance and injury prevention perspective, which may occur if the same muscle fibres in the same muscle are used in the same way in a repetitive manner. Interestingly, when a person suffers a stroke or a traumatic limb injury, the quantity of movement variability appears to paradoxically reduce rather than increase after the stroke or injury, and this reduced variability of motor function is associated with a decrement in task performance accuracy and completion. Therefore, the high variability of movement patterns in healthy folk appears to paradoxically make task performance more accurate and not just more efficient.

How control processes choose a specific ‘pattern’ of muscle activity for a specific task is still not well known. A number of theories have been proposed (generally as a rule in science, the more theories there are about something, the more the likelihood there is that there is no clarity about it) with some quaint names, such as the equilibrium point hypothesis, which suggests that choice at the motor neuron level is controlled as part of the force-length relationship of the muscle; the uncontrolled manifold hypothesis, which suggests that the central nervous system focuses on the variables needed to control a task and ignores the rest (the uncontrolled manifold being those variables that do not affect task required activity); and the force control hypothesis, which suggests that the central nervous systems compares the required movement for the task against internal models, and then uses calculations and feedforward and feedback control mechanisms to direct activity against that set by the internal model; amongst others. All these are interesting and intellectually rigorous theories, but don’t tell us very much about exactly how the brain chooses a particular group of muscles to perform a task, and then subsequently a different group of muscles, which use a different flight trajectory, to perform the task again when it is repeated. It has been suggested that there are ‘synergistic sets’ of muscles which are chosen in their entirety for a single movement, and that the primitive reflexes or central pattern generators in the spinal cord may be involved. But the bottom line is that we just do not currently know exactly what control mechanism chooses a specific set of muscles to perform one movement of a repetitive task, why different muscles are chosen each time the same task is performed sequentially, or how this variable use of muscles for the same task is managed and controlled.

We have previously suggested that a number of other activities in the body beyond that of muscle control have similar redundancy (or abundancy) in how they are regulated, or at least in respect of which mechanisms are used to control them. For example, blood glucose concentrations can be controlled not only by changes in insulin concentrations, but also by that of glucagon, and can also be altered by changes in catecholamine (adrenaline or noradrenaline) or cortisol levels, and indeed by behavioural factors such as resisting the urge to eat. Each time blood glucose concentrations are measured, the concentrations of all these other regulatory hormones and chemicals will be different ratio-wise to each other, yet their particular synergistic levels at any one point in time maintains the level of blood glucose concentrations at homeostatically safe setpoint levels. The blood glucose level is maintained whatever the variability in the regulatory factor concentration ratios, and even though this variability in choice of control mechanisms similarly creates a potential for high computational load when managing blood glucose concentrations from a control perspective. Similarly, perception of mood state or emotions are thought to have redundancy in what factors ‘creates’ them. For example we can fairly accurately rate when we feel slightly, moderately or very fatigued, but underpinning the ‘feeling’ of fatigue at the physiological level can be changes in blood glucose, heart rate, ventilation rate, and a host of other metabolites and substrates in the body, each of which can be altered in a variable ratio way to make up the sensation of fatigue we rate as slightly, moderately or very high levels of fatigue. Furthermore, fatigue is a complex sensation made up of individual sensations such as breathlessness, pounding chest, sweating, pain, and occasionally confusion, dizziness, headache and pins and needles, amongst others, a combination of which can also be differently valenced to provide a similar general fatigue rating by whoever is perceiving the sensation of fatigue. To make it even more complex, the sensation of fatigue is related to inner voices which either rate the sensation of fatigue (the ‘I’ voice) or make a judgement on it related to social circumstances or family and environmental background (the ‘Me’ voice), and it is through the final combination of these that an individual finally rates their level of fatigue, which adds another level of redundancy, or abundancy, to the factors underpinning how the ‘gestalt’ sensation of fatigue is both created and perceived. There are therefore three potential ‘levels’ of redundancy / abundancy in the signals and factors which either individually or collectively make up the ‘gestalt’ sensation of fatigue, and a corresponding increased level of computational requirements potentially associated with its final genesis, and how this perceptual redundancy / abundancy is managed by the control mechanisms which generate them is still not well known.

In summary, therefore, the presence of variability during activities of daily living across a number of different body systems is not only ‘noise’ / artefacts of testing conditions which are challenges for us researchers to have to deal with, it also appears to be part of some very complex control mechanisms which must have some teleological benefit both for optimizing movement and activity, and ensuring the capacity to sustain it without fatigue or injury to the components of the mechanism which produces it. Each time I cycle on my bike and my legs move up and down to push the wheels forward, different muscles are being used in a different way during each rotation of the wheel. Each time a darts player throws a dart, different muscle synergies are used to paradoxically create the accuracy of their throw. There is real ‘noise’ that a researcher has to remove from their recorded traces after a testing session in a laboratory, such as that caused by the study participant sweating during the trial, which can affect electrophysiological signals, and there is always a degree of measurement error, and therefore some degree of ‘noise’ is present in the variability of the recorded output for any laboratory technique that measures human function. But, equally, Bernstein’s brilliant work and observations all those years ago helped us understand that variability is inherent in living systems, and after understanding this, each time I observe data, particularly that generated during electrophysiological work such as I have used for a number of experiments in my own research career, including electromyography (EMG), electroencephalography (EEG) or transcranial magnetic stimulation (TMS), which has low standard deviations in the results sections of published research articles, I do wonder at the validity of the data and whether it has been ‘paintbrushed’ by the researchers who describe it, as my old Russian neurophysiology research colleague Mikhail Lomarev used to describe it, when he or we thought data was ‘suspect’. The inherent variability in brain and motor control systems makes finding statistical significance in results generated using routine neurophysiological techniques more difficult. It also seems to create a huge increase in the requisite control-related calculations and planning for even a simple movement, though as Mark Latash suggested, the brain is likely to not be a micro-manager, but rather some effective parsing mechanism which can both generate and utilize a large number of synergistic movement patterns in a variable manner for any task, while not utilizing much decision making power using some sort of heuristic-based decision-making mechanism. Most importantly though, it fills one with a sense of awe at the ‘magic’ of our own body, and for the level of complexity involved in both its creation and operative management, when even a simple movement like striking an object with a hammer, or cutting a piece of metal, can be underpinned by such complex control mechanisms that our brains cannot currently comprehend or make sense of.

In a laboratory in the middle of Russia nearly a century ago, Nikolai Bernstein made some astonishing observations by doing exceptional research on basic motor control, while trying to increase the productivity of soviet-era industrial work. A century later we are still scratching our heads trying to understand what his findings mean from a motor control perspective. As I type these final sentences, I reflect on this, and wonder which synergistic composition of muscle activity in my fingers are responsible for creating the actions which lead to these words being generated, and realize that each time I do so, because of the concepts of variability, redundancy and abundancy, I will probably never use an identical muscle sequence when typing other ideas into words at another future point in time. But then again, I guess the words I will be writing in the future will also be different, and daily life, like motor control programs, will always vary, always change, even though the nail on the wall on which the picture hangs becomes a permanent ‘item’, as will this article become permanent when I hit the ‘send’ button to publish it. What is never to be seen again though are the traces in the ‘ether’ of the hammer blow which embedded the nail in the wall, and the exact movement of the individual muscles in the labourers arms and hands, and in my fingers as I typed which created these words. Like magic their variability was created, and like magic their pattern has dispersed, never to recur again in the same way or place, unless some brilliant modern day Bernstein can solve their magic and mystery, reproduce them in their original form using some as yet to be invented laboratory device, and publish them in a monograph. Let’s hope that if they do so, their great work does not languish unseen for forty years before being discovered by the rest of the world’s scientists, as was Bernstein’s wonderful observations of all those years ago!

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The Core Requirement And Skill Of Decision-Making In Life – Removal Of Uncertainty Is Usually Positive And Cathartic But Is Also An Ephemeral Thing

This week, for the first time since moving to New Zealand and starting a new job here, I cycled in to work, and in the early afternoon faced a tough decision regarding whether I had the level of fitness capacity to cycle back home at the end of the day. Three-quarters of the way through the ride home, I felt very tired and stopped by the side of the road, and considered phoning home and asking them to pick me up. This morning I opened the fridge and had to decide whether to have the routine fruit and yogurt breakfast or the leftover piece of sausage roll. We have been six months in our new life and job here, and we have come to that period of time of deciding whether we have made a good decision and to continue, or whether we have made a disastrous error and need to make a rapid change. As I write this my wife asks me if I planned to go to the shop later, and if so whether I could get some milk for the family, and I had to stop writing and decide on whether I was indeed going to do so as part of the weekend post-writing chores, or not. All of these activities and issues required me to make decisions, and while some of them appeared to be of little consequence, some of them were potentially life and career changing, and, even if it seems a bit dramatic, potentially life-ending (whether to continue cycling when exhausted as a fifty-something). Decisions like these have to be made by everyone on a minute by minute basis as part of their routine daily life. The importance of decision-making in our daily lives, and how we make decisions, is still controversial and not well understood, which is surprising, given how much our optimal living condition and indeed survival depends on making correct decisions, and how often we have to make decisions, some of which are simple, some of which appear simple but are complex, and some of which are overtly complex.

Decision-making is defined as the cognitive process (which is the act or process of knowing or perceiving) resulting in the selection of a particular belief or course of action from several alternative possibilities, or as a problem-solving activity terminated by the genesis or arrival of a solution deemed to be satisfactory. At the heart of any decision-making is the requirement to choose between an array of different options, all of which usually have both positive and negative potential attributes and consequences, where one uses prior experience or a system of logical ‘steps’ to make the decision based on forecasting and scenario-setting for each possible alternative choice and consequence of choosing them. One of the best theoretical research articles on decision-making I have read / been involved with is one written by Dr Andy Renfree, an old colleague from the University of Worcester, and one of the Sport Science academic world’s most creative thinkers. As a systems level, he suggested that decisions are made based on either rational or heuristic principles, the former working best in ‘small world’ environments (in which the individual making the decision has absolute knowledge of all decision-related alternatives, consequences and probabilities), and the latter best in ‘large world’ environments (in which some relevant information is unknown or estimated). As described by Andy, rational decision-making is based on the principle that decisions can only be made if certain criteria are met, namely that the individuals making the decision must be faced with a set of behavioral alternatives and, importantly, information must be available for all possible alternatives of decisions that can be made, as well as of the statistical probability of all of the outcomes of the choices that can be made. This is obviously a large amount of requisite information, and a substantial period of time would be required to make a decision based on such ‘rational’ requirements. While using this method would likely be the most beneficial from a correct outcome perspective, it would also potentially place a high demand on the cognitive processes of the individual making the decision. Bayesian decision-making is a branch of rational decision-making theory, and suggests that decision-making is the result of unconscious probabilistic inferences. In Bayesian theory, a statistical approach to decision-making is made based on prior experience, with decision making valenced (and therefore speeded up) by applying a ‘bias’ towards information that is used to make the decision which is believed to be more ‘reliable’ than other information, and ‘probability’ of outcomes being better or worse based on prior experience. Therefore, in the Bayesian model, prior experience ‘speeds up’ decision making, though all information is still processed in this model.

In contrast, heuristic decision-making is a strategic method of making decisions, which ignores information that is available but is perceived to be less relevant to the specific decision being made, and which suggests that decisions are made based on key information and variables that are assessed and acted upon rapidly, in a manner that, as Andy suggests, incorporates ‘rule of thumb’ or ‘gut feel’ thinking, which places less demands on the cognitive thinking processes of the individual. As described above, rational decision-making may be more relevant in ‘small world’ environments, in which there are usually not a lot of variables or complexity which are required to be assessed prior to making a decision, and heuristic thinking in ‘large world’ environments, which are complex environments where all information, whether relevant or not, cannot be known, due to the presence not only of ‘known unknowns’ but also ‘unknown unknowns’, and where an individual would be potentially immobilized into a state of ‘cognitive paralysis’ if attempting to assess every option available. The problem or course is that even decisions that appear simple often have multiple layers of complexity that are not overt and of which the individual thinking about them is not aware, and it can be suggested that the concept of both rational and ‘small world’ environments are potentially abstract principles rather than reality, that all life occurs as part of ‘large world’ environments, and that heuristic processes are what are used by individuals as the main decision-making principles during all activities of daily living.

Of course, most folk would perceive that these rational and heuristic models are very computational and mathematical based, and that perhaps ‘feelings’ and ‘desires’ are also a component of decision-making, or at least these are how decision-making is perceived to ‘feel’ to them. As part of the Somatic Marker hypothesis, Antonio Damasio suggested that ‘body-loop’ associated emotional processes ‘guide’ (and have the potential to bias) decision-making behavior. In his theory, somatic markers are a specific ‘group of feelings’ in the body and are associated with specific emotions one perceives when confronted with, and are related to, the facts or choices one is faced with and need to make a decision about. There is suggested to be a different somatic marker for anxiety, enjoyment, or disgust, among other emotions, based on an aggregation of body-related symptoms for each, such as heart rate changes and the associated feeling of a pounding chest, the sensation of breathing changes, changes in body temperature, increased sweat rate, or the symptom of nausea, some or all of which together are part of a certain somatic marker group which creates the ‘feeling’ of a particular emotion. Each of these physiologically based body-loop ‘states’ are capable of being components of different somatic marker ‘groups’, which create the distinct ‘feelings’ which are associated with different emotions, and which would valence decisions differently depending on which somatic marker state / emotion is created by thinking of a specific option or choice. This hypothesis is based on earlier work by William James and colleagues more than a hundred years ago, which became the James-Lange theory of emotion, which suggests there is a ‘body-loop’ required for the ‘feeling’ of emotions in response to some external challenge, which is in turn required for decision-making processes related to the external challenge. The example used to explain this theory was that when one sees a snake, it creates a ‘body loop’ of raised heart rate, increased sweating, increased breath rate and the symptom of nausea, all of which in turn create the ‘feeling’ of fear once these ‘body-loop’ symptoms are perceived by the brain, and it was hypothesized that it is these body-generated feelings, rather than the sight of the snake itself, which induces both the feeling of fear and the decision to either rapidly run away or freeze and hope the snake moves away. While this model is contentious as it would make reactions occur slower than if a direct cognitive decision-making loop occurred, it does explain the concept of a ‘gut feel’ when decision-making. Related to this ‘body-loop’ theory, are other behavioral theories about decision-making, and it has been suggested that decisions are based on what the needs, preferences and values of an individual are, such as hunger, lust, thirst, fear, or moral viewpoint, but of course all of these could equally be described as components of either a rational or heuristic model, and psychological / emotional and cognitive / mathematical models of decision-making are surely not mutually exclusive conditions or theories.

These theories described above attempt to explain how and why we make decisions, but not what causes decisions to be right or wrong. Indeed, perhaps the most relevant issue to most folk is why they so often get decisions wrong. A simple reason may be that of ‘decision fatigue’, whereby the quality of decision-making deteriorates after a prolonged period of decision-making. In other words, one may simply ‘run out’ of the mental energy which is required to make sound decisions, perhaps due to ongoing changes in ‘somatic markers’ / body symptoms each time a decision is required to be made, which creates an energy cost that eventually ‘uses up’ mental energy (whatever mental energy is) over the period of time sequential decisions are required to be made. Astonishingly, judges working in court have been shown to make less favorable decisions as a court session progresses, and the number of favorable decisions improves after the judges have had a break. Apart from these data suggesting that one should ask for a court appearance early on in the morning or after a break, it also suggests that either physical or mental energy in these judges is finite, and ‘runs out’ with prolonged effort and the use of energy focusing on decision-making related to each case over the time period of a court session. There are other more subtle potential causes of poor-decision making. For example, confirmation bias occurs when folk selectively search for evidence that supports a certain decision that they ‘want’ to make, based on an inherent cognitive bias set in their mind by past events or upbringing, even if their ‘gut’ is telling them that it is the wrong decision. Cognitive inertia occurs when folk are unwilling to change their existing environment or thought patterns even when new evidence or circumstances suggest they should. People tend to remember more recent information and use it preferentially, or forget older information, even if the older information is potentially more valid. Repetition bias is caused by folk making decisions based on what they have been told, if it has been told to them by the greatest number of different people, and ‘groupthink’ is when peer pressure to conform to an opinion or group action causes the individual to make decisions they would not do if they were alone and not in the group. An ‘illusion of control’ in decision-making occurs where people have a tendency to under-estimate uncertainty because of a belief that they have more control over events that they actually have. While folk with anxiety tend to make either very conservative or paradoxically very rash decisions, sociopaths, who are thought to have little or no emotional ‘body-loop’, are very poor at making moral based decisions or judgments. Therefore, there are a whole lot of different factors which can impact negatively on decision-making, either due to one’s upbringing or prior history impacting on the historical memory which is used to valence decisions, or due to one’s current emotional or psychological state having a negative impact on decision-making capacity, and even simple fatigue can be the root cause of poor decision-making.

At the heart of decision-making (excusing the pun, from the perspective of the somatic marker hypothesis), is a desire of most folk to remove uncertainty from their lives, or change their life or situation to a better state or place as a result of their decision, or to remove a stressor from their life that will continue unless they make a decision on how to resolve it, remove it, or remove themselves from whatever causes the stressor. However, during my days as a researcher at the University of Cape Town, we suggested that conditions of uncertainty and certainty associated with information processing and decision-making are cyclical (we called it the ‘quantal packet’ information processing theory, for those interested). A chosen decision will change a position or state of uncertainty to one of certainty as one enacts changes based on the decision (or if one chooses to ‘wait and see’ and not alter anything) from the context that one is certain a change will occur based on what one has decided to do, even if one cannot be sure if this difference will be positive or negative while the changes are being enacted. However, with the passing of time, the effects of the decision made will attenuate, and uncertainty will eventually re-occur which require a further decision to be made, often with similar choices to which occurred when the initial decision was made. Underpinning this attenuation of the period of ‘certainty’ is the concept that although one will have factored in ‘known unknowns’ into any decision one makes using either rational or heuristic principles, ‘unknown unknowns’ will surely always occur that will cause even the best strategic decisions to require tactical adjustments, and those that are proven to be an error will need to be reviewed and changed. One can also ‘over-think’ decision-making as much as one can ‘under-think’ it, as well as being kept ‘hostage’ to cognitive biases from one’s past which continuously ‘trip one up’ when making decisions, despite one’s best intentions. Having said all of this, it often astonishes me not that folk get decisions wrong, but rather that they get so many decisions right. For example, when driving along a highway, one is reliant on the correct decisions of every driver that passes for one’s survival, from how much they choose to turn their steering wheel, to how much they use their brake for a corner, to an awareness in each of them that they are not too tired to be driving in the first place. It’s amazing when one thinks of how many decisions we make, either consciously or unconsciously, which so often turn out right, but equally it is the responsibility of each of us to work on the errors created by our past, or by our emotional state, or by ‘groupthink’, which we need to be vigilant about and remove as best possible from the psyche.

Making a decision is usually cathartic due to the removal of uncertainty and the associated anxiety which uncertainty often causes, even if the certainty and feeling of goodwill generated by making a decision is usually ephemeral and lasts only for a short period of time before other matters occupy one’s attention which require further decision-making. Pondering on my decision-making of the last week retrospectively, I think I made the right decision when choosing to cycle home after work, and to do so all the way home, even if I was exhausted when I got there, given that I did not collapse or have a heart attack when doing so, and there will surely be long term health benefits from two long cycles (though of course long is relative at my age!) in one day. I did choose the healthy food alternative for breakfast this morning, even though often I don’t, particularly during meals when I am tired after a long day’s work. I will get the milk my wife asked me to get this afternoon, in order to both get some fresh air after a creative morning of thinking and writing, and to maintain the harmony in our house and life, even though it is raining hard and I would prefer to be writing more or reading a good book this afternoon. The ‘jury is still out’ about whether this move to New Zealand and a new work role has been a good career and country move, and my current decision on this is to let more time pass before making an action-generating reasoned decision on it, though of course we have already moved several times to new places round the world in the last two decades, and the family is looking forward to some lifestyle stability in the next few years, and these factors need to be part of any reflection on a current-environment rating decision. Each of these decisions seemed ostensibly relatively simple to make when I made them, yet each surely had an associated entire host of different reasons, experiences, memories and requirements which were worked through in and by my mind before making them, as will be so for all folk making decisions on all aspects of their life during a routine day. What will I have for lunch now I am finished writing this and am now tired and in need of a break and sustenance? Perhaps I will leave off that decision and relax for a period of time before making lunch-related choices, so as not to make a fatigue-induced bad decision, and reach for that sausage roll, which still is in the fridge. And I need to get going and enact that decision I made to get the milk, and head off to the shops in order to do so as soon as possible, before lethargy set in and I change my mind, otherwise I will surely be in the ‘dog box’ at home later this afternoon, and my sense of cathartic peace resulting from having made these decisions will be even more ephemeral than usual!


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