3D Printing Plastic Scintillators

Scintillation is the production of visible light in a transparent material when exposed to either an electron, ion, or some other high energy particle. There are many ways to manufacture scintillators, but unfortunately many of these methods involve the costly machining of crystal materials. We plan to reduce this cost by attempting to manufacture plastic scintillators using a 3D printer. The most difficult challenge has been making transparent prints. We have had success with PET filament, the same plastic used in soda bottles. Upon successful clear prints, we intend to use recycled bottles to manufacture our own doped fiber. Organic compounds such as Naphthalene and Anthracene are our targeted doping compounds

Consumption of Bats (Myotis spp.) by Raccoons (Procyon lotor) During an Outbreak of White-Nose Syndrome in New Brunswick, Canada: Implications for Estimates of Bat Mortality

Across their range, Raccoons (Procyon lotor) will opportunistically exploit bats (Chiroptera) roosting in caves as a source of food. During a significant mortality event associated with white-nose syndrome (WNS) at a cave in eastern Canada, we estimate that Raccoons consumed 3169–3827 dead and dying Little Brown Bats (Myotis lucifugus) and Northern Long-eared Bats (M. septentrionalis) infected with white-nose syndrome, equivalent to 62.0–74.9% of the total bat mortality at this site. However, the generally small dispersal distances of Raccoons and their reduced activity during the period when bats are hibernating suggest that Raccoons are likely not a significant vector for moving the fungus associated with white-nose syndrome, Geomyces destructans, between most caves at this latitude. Nevertheless, since we show that significant numbers of bats can be consumed in hibernacula through opportunistic feeding by Raccoons, estimates of in-cave mortality due to white-nose syndrome should incorporate any evidence of consumption of bats by Raccoons and other predators

Chlorpromazine reduces avoidance performance deficit in rats with dorsomedial thalamic lesions

Rats with bilateral lesions of the dorsomedial area of the thalamus were shown to have a significant performance deficit on the acquisition of a one-way active shock-avoidance task relative to sham-operated controls. Administration of chlorpromazine prior to testing was shown to reduce this deficit among the DMT-lesioned animals

DETECTING VIABLE PSEUDOGYMNOASCUS DESTRUCTANS (ASCOMYCOTA: PSEUDEUROTIACEAE) FROM WALLS OF BAT HIBERNACULA: EFFECT OF CULTURE MEDIA

Abstract: Pseudogymnoascus destructans (Pd) causes the fungal disease white-nose syndrome (WNS), which has led to high mortality in some hibernating bat species in eastern North America. The ability to detect viable Pd in hibernacula is important for understanding the role the environment plays as a reservoir for infectious Pd. Previous studies have generally used the high-sugar medium Sabouraud-dextrose (SAB) and have had low yields of viable Pd from environmental samples of Pd-positive hibernacula. While cultureindependent methods (i.e., molecular genetics) have previously shown much better success in detecting Pd, these methods cannot determine viability. In 2012 and 2015, we swabbed walls in four hibernacula with WNS-positive bats in New Brunswick, Canada, and cultured the samples using dextrose-peptone-yeast extract agar (DPYA), SAB, and Malt extract (MEA) media. Samples cultured on DPYA produced viable Pd 43.7 to 50.0 % more frequently than SAB, with a maximum overall return for DPYA among sites of 62.5 % Pd-positive samples over both years. During the initial outbreak of WNS in our study region, Pd-positive swabs were produced from 40.0 to 83.3 % of samples on DPYA, whereas SAB produced a maximum of 40.0 %. At one site we detected Pd from 83.3% of swabs cultured on DPYA and 0 % on SAB. MEA produced no viable Pd. Our figures for Pd detection are as high as or higher than previously published culture-independent methods, while also confirming the viability of the Pd present. We found that the yield of viable Pd from hibernacula walls decreased from 2012 to 2015 as the hibernating bat population decreased due to WNS mortality, but patterns varied amongst hibernacula, and overall, were not statistically different. It is possible that environmental growth of Pd contributes to its persistence within hibernacula. We suggest that future studies on the environmental persistence of viable Pd discontinue the use of high-sugar media that lack inhibitory fungal growth ingredients, such as SAB and MEA, as they favor fast-growing fungal species that overgrow and mask slowergrowing fungi such as Pd

Transient inhibition and long-term facilitation of locomotion by phasic optogenetic activation of serotonin neurons

Serotonin (5-HT) is associated with mood and motivation but the function of endogenous 5-HT remains controversial. Here, we studied the impact of phasic optogenetic activation of 5-HT neurons in mice over time scales from seconds to weeks. We found that activating dorsal raphe nucleus (DRN) 5-HT neurons induced a strong suppression of spontaneous locomotor behavior in the open field with rapid kinetics (onset ≤1 s). Inhibition of locomotion was independent of measures of anxiety or motor impairment and could be overcome by strong motivational drive. Repetitive place-contingent pairing of activation caused neither place preference nor aversion. However, repeated 15 min daily stimulation caused a persistent increase in spontaneous locomotion to emerge over three weeks. These results show that 5-HT transients have strong and opposing short and long-term effects on motor behavior that appear to arise from effects on the underlying factors that motivate actions.info:eu-repo/semantics/publishedVersio

Increased mesiotemporal delta activity characterizes virtual navigation in humans

Hippocampal theta or rhythmic slow activity (RSA) occurring during exploratory behaviors and rapid-eye-movement (REM) sleep is a characteristic and well-identifiable oscillatory rhythm in animals. In contrast, controversy surrounds the existence and electrophysiological correlates of this activity in humans. Some argue that the human hippocampal theta occurs in short and phasic bursts. On the contrary, our earlier studies provide evidence that REM-dependent mesiotemporal RSA is continuous like in animals but instead of the theta it falls in the delta frequency range. Here we used a virtual navigation task in 24 epilepsy patients implanted with foramen ovale electrodes. EEG was analyzed for 1-Hz wide frequency bins up to 10 Hz according to four conditions: resting, non-learning route-following, acquisition and recall. We found progressively increasing spectral power in frequency bins up the 4 Hz across these conditions. No spectral power increase relative to resting was revealed within the traditional theta band and above in any of the navigation conditions. Thus the affected frequency bins were below the theta band and were similar to those characterizing REM sleep in our previous studies providing further indication that it is delta rather than theta that should be regarded as a human analogue of the animal RSA

Replay as wavefronts and theta sequences as bump oscillations in a grid cell attractor network.

Grid cells fire in sequences that represent rapid trajectories in space. During locomotion, theta sequences encode sweeps in position starting slightly behind the animal and ending ahead of it. During quiescence and slow wave sleep, bouts of synchronized activity represent long trajectories called replays, which are well-established in place cells and have been recently reported in grid cells. Theta sequences and replay are hypothesized to facilitate many cognitive functions, but their underlying mechanisms are unknown. One mechanism proposed for grid cell formation is the continuous attractor network. We demonstrate that this established architecture naturally produces theta sequences and replay as distinct consequences of modulating external input. Driving inhibitory interneurons at the theta frequency causes attractor bumps to oscillate in speed and size, which gives rise to theta sequences and phase precession, respectively. Decreasing input drive to all neurons produces traveling wavefronts of activity that are decoded as replays

Decapitation in Rats: Latency to Unconsciousness and the ‘Wave of Death’

The question whether decapitation is a humane method of euthanasia in awake animals is being debated. To gather arguments in this debate, obsolete rats were decapitated while recording the EEG, both of awake rats and of anesthetized rats. Following decapitation a fast and global loss of power of the EEG was observed; the power in the 13–100 Hz frequency band, expressing cognitive activity, decreased according to an exponential decay function to half the initial value within 4 seconds. Whereas the pre-decapitation EEG of the anesthetized animals showed a burst suppression pattern quite different from the awake animals, the power in the postdecapitation EEG did not differ between the two groups. This might indicate that either the power of the EEG does not correlate well with consciousness or that consciousness is briefly regained in the anesthetized group after decapitation. Remarkably, after 50 seconds (awake group) or 80 seconds (anesthetized group) following decapitation, a high amplitude slow wave was observed. The EEG before this wave had more power than the signal after the wave. This wave might be due to a simultaneous massive loss of membrane potentials of the neurons. Still functioning ion channels, which keep the membrane potential intact before the wave, might explain the observed power difference. Two conclusions were drawn from this experiment. It is likely that consciousness vanishes within seconds after decapitation, implying that decapitation is a quick and not an inhumane method of euthanasia. It seems that the massive wave which can be recorded approximately one minute after decapitation reflects the ultimate border between life and death. This observation might have implications in the discussions on the appropriate time for organ donation

Persistent Hyperdopaminergia Decreases the Peak Frequency of Hippocampal Theta Oscillations during Quiet Waking and REM Sleep

Long-term changes in dopaminergic signaling are thought to underlie the pathophysiology of a number of psychiatric disorders. Several conditions are associated with cognitive deficits such as disturbances in attention processes and learning and memory, suggesting that persistent changes in dopaminergic signaling may alter neural mechanisms underlying these processes. Dopamine transporter knockout (DAT-KO) mice exhibit a persistent five-fold increase in extracellular dopamine levels. Here, we demonstrate that DAT-KO mice display lower hippocampal theta oscillation frequencies during baseline periods of waking and rapid-eye movement sleep. These altered theta oscillations are not reversed via treatment with the antidopaminergic agent haloperidol. Thus, we propose that persistent hyperdopaminergia, together with secondary alterations in other neuromodulatory systems, results in lower frequency activity in neural systems responsible for various cognitive processes