Energetics of a sudden stratospheric warming simulated with a three-dimensional, spectral, quasi-geostrophic model

The energetics of a three dimensional, quasi-geostrophic simulation of a sudden stratospheric warming which developed spontaneously during an annual cycle simulation are described. Daily values of the stratospheric temperatures, zonal winds, heating rates, energies, and energy conversions are discussed and compared with those for observed warmings. It is shown that, like observed warmings, the simulated warming was preceded by an increased vertical flux of eddy kinetic energy from the troposphere and the polar heating resulted because of the strong convergence of the horizontal, eddy heat flux which was only partially balanced by adiabatic and diabatic cooling. There is a significant similarity between the energetics of the simulated and observed warmings. In addition, the warming was spontaneous and the model did not develop a major warming in each winter of the simulation. These facts suggest that this model may be useful for studying not only the warming process but also the conditions that favor its development

National Forest Minerals Management [outline]

3 pages

Feeling free: External influences on endogenous behaviour

When we are presented with two equally appealing options, how does the brain break the symmetry between them and make a choice? Recent research has proposed that when no clear information can guide decisions, we use irrelevant noise to tip the scale in favour of one alternative and decide how to act. In the present study, we investigated this issue exploring how human decisions were influenced by noise in a visual signal that cued instructed or free choice. Participants were presented with random-dot kinematograms, moving unidirectionally either upwards or downwards (in instructed trials) or both upwards and downwards simultaneously (free-choice trials). By varying the coherence of dot motion, we were able to test how moment-to-moment fluctuations in motion energy could influence action selection processes. We also measured participants' awareness of such influence. Our results revealed three novel findings: Participants' choices tended to follow fluctuations in dot motion, showing that sensory noise biased "free" selection between actions, irrespective of the clarity of the free cue. However, participants appeared to remain unaware of that influence, because subjective ratings of freedom did not correlate with the degree of sensory biasing. In one exception to this general rule, we found that, when participants resisted the bias and made a choice opposite to the one suggested by the stimulus, they reported strong subjective sense of having chosen independently of the stimulation. This result suggests that inhibitory control is tightly linked to the sense of freedom of choice

Acting without being in control: Exploring volition in Parkinson's disease with impulsive compulsive behaviours.

BACKGROUND: Several aspects of volitional control of action may be relevant in the pathophysiology of impulsive-compulsive behaviours (ICB) in Parkinson's disease (PD). We aimed to explore multiple aspects of action control, assessing reward-related behaviour, inhibition (externally and internally triggered) and sense of agency in PD patients, with and without ICB compared to healthy subjects. METHODS: Nineteen PD patients with ICB (PD-ICB), 19 PD without ICB (PD-no-ICB) and 19 healthy controls (HC) underwent a battery of tests including: Intentional Binding task which measures sense of agency; Stop Signal Reaction Time (SSRT) measuring capacity for reactive inhibition; the Marble task, assessing intentional inhibition; Balloon Analog Risk Task for reward sensitivity. RESULTS: One-way ANOVA showed significant main effect of group for action binding (p = 0.004, F = 6.27). Post hoc analysis revealed that PD-ICB had significantly stronger action binding than HC (p = 0.004), and PD-no-ICB (p = 0.04). There was no difference between PD-no-ICB and HC. SSRT did not differ between PD groups, whereas a significant difference between PD-no-ICB and HC was detected (p = 0.01). No other differences were found among groups in the other tasks. CONCLUSIONS: PD patients with ICB have abnormal performance on a psychophysical task assessing sense of agency, which might be related to a deficit in action representation at cognitive/experiential level. Yet, they have no deficit on tasks evaluating externally and internally triggered inhibitory control, or in reward-based decision-making. We conclude that impaired sense of agency may be a factor contributing to ICB in PD patients

The Chandra Dust Scattering Halo of Galactic Center transient Swift J174540.7-290015

We report the detection of a dust scattering halo around a recently discovered X-ray transient, Swift J174540.7-290015, which in early February of 2016 underwent one of the brightest outbursts (F_X ~ 5e-10 erg/cm^2/s) observed from a compact object in the Galactic Center field. We analyze four Chandra images that were taken as follow-up observations to Swift discoveries of new Galactic Center transients. After adjusting our spectral extraction for the effects of detector pileup, we construct a point spread function for each observation and compare it to the GC field before the outburst. We find residual surface brightness around Swift J174540.7-290015, which has a shape and temporal evolution consistent with the behavior expected from X-rays scattered by foreground dust. We examine the spectral properties of the source, which shows evidence that the object transitioned from a soft to hard spectral state as it faded below L_X ~ 1e36 erg/s. This behavior is consistent with the hypothesis that the object is a low mass X-ray binary in the Galactic Center.Comment: Accepted for publication in Ap

Autonomous behaviour and the limits of human volition.

Humans and some other animals can autonomously generate action choices that contribute to solving complex problems. However, experimental investigations of the cognitive bases of human autonomy are challenging, because experimental paradigms typically constrain behaviour using controlled contexts, and elicit behaviour by external triggers. In contrast, autonomy and freedom imply unconstrained behaviour initiated by endogenous triggers. Here we propose a new theoretical construct of adaptive autonomy, meaning the capacity to make behavioural choices that are free from constraints of both immediate external triggers and of routine response patterns, but nevertheless show appropriate coordination with the environment. Participants (N = 152) played a competitive game in which they had to choose the right time to act, in the face of an opponent who punished (in separate blocks) either choice biases (such as always responding early), sequential patterns of action timing across trials (such as early, late, early, late…), or predictable action-outcome dependence (such as win-stay, lose-shift). Adaptive autonomy was quantified as the ability to maintain performance when each of these influences on action selection was punished. We found that participants could become free from habitual choices regarding when to act and could also become free from sequential action patterns. However, they were not able to free themselves from influences of action-outcome dependence, even when these resulted in poor performance. These results point to a new concept of autonomous behaviour as flexible adaptation of voluntary action choices in a way that avoids stereotypy. In a sequential analysis, we also demonstrated that participants increased their reliance on belief learning in which they attempt to understand the competitor's beliefs and intentions, when transition bias and reinforcement bias were punished. Taken together, our study points to a cognitive mechanism of adaptive autonomy in which competitive interactions with other agents could promote both social cognition and volition in the form of non-stereotyped action choices

Bioassessment of Four Karst Springs at Hobbs State Park – Conservation Area with a Focus on Diving Beetle (Dytiscidae: Hydroporinae) Species of Concern

Four springs were surveyed at Hobbs State Park-Conservation Area to provide an initial bioassessment and to determine occurrences of two endemic predaceous diving beetles of concern, Heterosternuta sulphuria and Sanfilippodytes sp. Habitat in the four spring runs were dominated by bedrock and gravel substrate with heavy accumulations of leaf litter. Thirty-three taxa representing 11 orders were collected from the four springs. Non-insect taxa included Oligochaeta, Physidae, and Isopoda, and predominant insect orders included Ephemeroptera, Coleoptera, Diptera, and Trichoptera. The total number of taxa across springs ranged from seven to 19, with total abundances ranging from 39 to 86 individuals. No individual taxon occurred across all four springs. Percent tolerant organisms and the Hilsenhoff Biotic Index showed that spring communities were dominated by taxa tolerant to organic pollution, likely because of low flows and heavy accumulations of leaves. Predators were the dominant functional group followed by shredders. The endemic, predaceous diving beetle Heterosternuta sulphuria was collected from two springs and Sanfilippodytes sp. was collected from three springs. One spring contained the largest number of Sanfilippodytes sp. individuals recorded among all other aquatic habitats surveyed to date. Findings highlight the importance of spring systems at Hobbs State Park Conservation Area for endemic-species conservation, while information on the invertebrate community provides a baseline for future monitoring and comparison

Sensorimotor signals underlying space perception: An investigation based on self-touch

Perception of space has puzzled scientists since antiquity, and is among the foundational questions of scientific psychology. Classical “local sign” theories assert that perception of spatial extent ultimately derives from efferent signals specifying the intensity of motor commands. Everyday cases of self-touch, such as stroking the left forearm with the right index fingertip, provide an important platform for studying spatial perception, because of the tight correlation between motor and tactile extents. Nevertheless, if the motor and sensory information in self-touch were artificially decoupled, these classical theories would clearly predict that motor signals – especially if self-generated rather than passive – should influence spatial perceptual judgements, but not vice versa. We tested this hypothesis by quantifying the contribution of tactile, kinaesthetic, and motor information to judgements of spatial extent. In a self-touch paradigm involving two coupled robots in master-slave configuration, voluntary movements of the right-hand produced simultaneous tactile stroking on the left forearm. Crucially, the coupling between robots was manipulated so that tactile stimulation could be shorter, equal, or longer in extent than the movement that caused it. Participants judged either the extent of the movement, or the extent of the tactile stroke. By controlling sensorimotor gains in this way, we quantified how motor signals influence tactile spatial perception, and vice versa. Perception of tactile extent was strongly biased by the amplitude of the movement performed. Importantly, touch also affected the perceived extent of movement. Finally, the effect of movement on touch was significantly stronger when movements were actively-generated compared to when the participant's right hand was passively moved by the experimenter. Overall, these results suggest that motor signals indeed dominate the construction of spatial percepts, at least when the normal tight correlation between motor and sensory signals is broken. Importantly, however, this dominance is not total, as classical theory might suggest

Mistaking opposition for autonomy: psychophysical studies on detecting choice bias

Do people know when they act freely and autonomously versus when their actions are influenced? While the human aspiration to freedom is widespread, little research has investigated how people perceive whether their choices are biased. Here, we explored how actions congruent or incongruent with suggestions are perceived as influenced or free. Across three experiments, participants saw directional stimuli cueing left or right manual responses. They were instructed to follow the cue's suggestion, oppose it or ignore it entirely to make a 'free' choice. We found that we could bias participants' 'free responses' towards adherence or opposition, by making one instruction more frequent than the other. Strikingly, participants consistently reported feeling less influenced by cues to which they responded incongruently, even when response habits effectively biased them towards such opposition behaviour. This effect was so compelling that cues that were frequently presented with the Oppose instruction became systematically judged as having less influence on behaviour, artificially increasing the sense of freedom of choice. Taken together, these findings demonstrate that acting contrarian distorts the perception of autonomy. Crucially, we demonstrate the existence of a novel illusion of freedom evoked by trained opposition. Our results have important implications for understanding mechanisms of persuasion