Dense molecular clumps in the envelope of the yellow hypergiant IRC+10420

The circumstellar envelope of the hypergiant star IRC+10420 has been traced as far out in SiO J=2-1 as in CO J = 1-0 and CO J = 2-1, in dramatic contrast with the centrally condensed (thermal) SiO- but extended CO-emitting envelopes of giant and supergiant stars. Here, we present an observation of the circumstellar envelope in SiO J=1-0 that, when combined with the previous observation in {\sioii}, provide more stringent constraints on the density of the SiO-emitting gas than hitherto possible. The emission in SiO peaks at a radius of $\sim$2\arcsec\ whereas that in SiO J=2-1 emission peaks at a smaller radius of $\sim$1\arcsec, giving rise to their ring-like appearances. The ratio in brightness temperature between SiO J=1-0 and SiO J=2-1 decreases from a value well above unity at the innermost measurable radius to about unity at radius of $\sim$2\arcsec, beyond which this ratio remains approximately constant. Dividing the envelope into three zones as in models for the CO J = 1-0 and CO J = 2-1 emission, we show that the density of the SiO-emitting gas is comparable with that of the CO-emitting gas in the inner zone, but at least an order of magnitude higher by comparison in both the middle and outer zones. The SiO-emitting gas therefore originates from dense clumps, likely associated with the dust clumps seen in scattered optical light, surrounded by more diffuse CO-emitting interclump gas. We suggest that SiO molecules are released from dust grains due to shock interactions between the dense SiO-emitting clumps and the diffuse CO-emitting interclump gas.Comment: Accepted for publication in Ap

On sensorimotor function and the relationship between proprioception and motor learning

Research continues to explore the mechanisms that mediate successful motor control. Behaviourally-relevant modulation of muscle commands is dependent on sensory signals. Proprioception -- the sense of body position -- is one signal likely to be crucial for motor learning. The present thesis explores the relationship between human proprioception and motor learning. First we investigated changes to sensory function during the adaptation of arm movements to novel forces. Subjects adapted movements in the presence of directional loads over the course of learning. Psychophysical estimates of perceived hand position showed that motor learning resulted in sensed hand position becoming \emph{biased} in the direction of the experienced load. This biasing of perception occurred for four different perturbation directions and remained even after washout movements. Therefore, motor learning can result in systematic changes to proprioceptive function. In a second experiment we investigated proprioceptive changes after subjects learned highly accurate movements to targets. Subjects demonstrated improved acuity of the hand\u27s position following this type of motor learning. Interestingly, improved acuity did not generalize to the entire workspace but was instead restricted to local positions within the region of the workspace where motor learning occurred. These results provide evidence that altered sensory function from motor learning may also include sensory acuity improvements. Subsequently the duration of acuity improvements was assessed. Improved acuity of hand position was observed immediately after motor learning and 24h later, but was not reliably different from baseline at 1h or 4h. Persistent sensory change may thus be similar to retention of motor learning and may involve a sleep-dependent component. In the fourth study we investigated the ability of proprioceptive training to improve motor learning. Subjects had to match the position and speed of desired trajectories. At regular intervals during motor motor learning, subjects were presented with the desired trajectory either only visually, or with both vision and and passive proprioceptive movement through the desired trajectory using a robot. Subjects who received proprioceptive guidance indeed performed better in matching both velocity and position of desired movements, suggesting a role for passive proprioceptive training in improving motor learning

A murine model of variant late infantile ceroid lipofuscinosis recapitulates behavioral and pathological phenotypes of human disease.

Neuronal ceroid lipofuscinoses (NCLs; also known collectively as Batten Disease) are a family of autosomal recessive lysosomal storage disorders. Mutations in as many as 13 genes give rise to ∼10 variants of NCL, all with overlapping clinical symptomatology including visual impairment, motor and cognitive dysfunction, seizures, and premature death. Mutations in CLN6 result in both a variant late infantile onset neuronal ceroid lipofuscinosis (vLINCL) as well as an adult-onset form of the disease called Type A Kufs. CLN6 is a non-glycosylated membrane protein of unknown function localized to the endoplasmic reticulum (ER). In this study, we perform a detailed characterization of a naturally occurring Cln6 mutant (Cln6(nclf)) mouse line to validate its utility for translational research. We demonstrate that this Cln6(nclf) mutation leads to deficits in motor coordination, vision, memory, and learning. Pathologically, we demonstrate loss of neurons within specific subregions and lamina of the cortex that correlate to behavioral phenotypes. As in other NCL models, this model displays selective loss of GABAergic interneuron sub-populations in the cortex and the hippocampus with profound, early-onset glial activation. Finally, we demonstrate a novel deficit in memory and learning, including a dramatic reduction in dendritic spine density in the cerebral cortex, which suggests a reduction in synaptic strength following disruption in CLN6. Together, these findings highlight the behavioral and pathological similarities between the Cln6(nclf) mouse model and human NCL patients, validating this model as a reliable format for screening potential therapeutics

The Compromise Effect in Market Settings

The attraction effect and compromise effect are common factors when making choices in one’s daily life or in market settings. The problem under investigation was if the compromise effect with more realistic settings would still produce the same results as previous literature suggests (Huber et al., 1982; Huber & Puto, 1983; Sheng, et al., 2005; Simonson, 1989; Simonson & Tversky, 1992) and if the implementation of a “sold out” condition would be an important condition that would influence participant’s choices of products. 36 participants were divided into three groups in study 1 (set 1, set 2, set 3 of products). Similarly in the second study, a total of 88 participants were divided into three groups (dual product condition, compromise condition, and sold out condition). In study 1, the compromise effect was evident with more realistic settings. The findings of study 2 showed that in the sold out condition, participants chose the lesser quality products. The results of both studies allow marketers and consumers to strategize their decisions when buying or selling products

Knotted and Linked Products of recombination on T(2,n)#T(2,m) Substrates

We develop a topological model of site-specific recombination that applies to substrates which are the connected sum of two torus links of the form T(2,n)#T(2,m). Then we use our model to prove that all knots and links that can be produced by site-specific recombination on such substrates are contained in one of two families, which we illustrate