Dynamic weather effects induced from the 2017 total solar eclipse

This research project was part of a nationwide effort organized by Montana Space Grant consortium to study and film the 2017 total solar eclipse with high altitude balloons. Our mission is to measure the changes in light from the total solar eclipse and its effects on the local weather conditions in the air and on the ground. Our results showed that the effects of totality on the ambient light levels were not gradual, like we had expected from our observations of sunsets, but rather the light levels decreased sharply at totality. We measured a 5.61% decrease in light before full totality, followed by a 94.4% decrease, over 90 seconds, into totality. The dramatic decreases in light levels are the root cause for the measured weather phenomena, including a short-term pressure increase associated with totality

RNAi: double-stranded RNA directs the ATP-dependent cleavage of mRNA at 21 to 23 nucleotide intervals

Double-stranded RNA (dsRNA) directs the sequence-specific degradation of mRNA through a process known as RNA interference (RNAi). Using a recently developed Drosophila in vitro system, we examined the molecular mechanism underlying RNAi. We find that RNAi is ATP dependent yet uncoupled from mRNA translation. During the RNAi reaction, both strands of the dsRNA are processed to RNA segments 21-23 nucleotides in length. Processing of the dsRNA to the small RNA fragments does not require the targeted mRNA. The mRNA is cleaved only within the region of identity with the dsRNA. Cleavage occurs at sites 21-23 nucleotides apart, the same interval observed for the dsRNA itself, suggesting that the 21-23 nucleotide fragments from the dsRNA are guiding mRNA cleavage

StdpC: a modern dynamic clamp

With the advancement of computer technology many novel uses of dynamic clamp have become possible. We have added new features to our dynamic clamp software StdpC (“Spike timing-dependent plasticity Clamp”) allowing such new applications while conserving the ease of use and installation of the popular earlier Dynclamp 2/4 package. Here, we introduce the new features of a waveform generator, freely programmable Hodgkin–Huxley conductances, learning synapses, graphic data displays, and a powerful scripting mechanism and discuss examples of experiments using these features. In the first example we built and ‘voltage clamped’ a conductance based model cell from a passive resistor–capacitor (RC) circuit using the dynamic clamp software to generate the voltage-dependent currents. In the second example we coupled our new spike generator through a burst detection/burst generation mechanism in a phase-dependent way to a neuron in a central pattern generator and dissected the subtle interaction between neurons, which seems to implement an information transfer through intraburst spike patterns. In the third example, making use of the new plasticity mechanism for simulated synapses, we analyzed the effect of spike timing-dependent plasticity (STDP) on synchronization revealing considerable enhancement of the entrainment of a post-synaptic neuron by a periodic spike train. These examples illustrate that with modern dynamic clamp software like StdpC, the dynamic clamp has developed beyond the mere introduction of artificial synapses or ionic conductances into neurons to a universal research tool, which might well become a standard instrument of modern electrophysiology

An experimental study of the rearrangements of valence protons and neutrons amongst single-particle orbits during double {\beta} decay in 100Mo

The rearrangements of protons and neutrons amongst the valence single-particle orbitals during double {\beta} decay of 100Mo have been determined by measuring cross sections in (d,p), (p,d), (3He,{\alpha}) and (3He,d) reactions on 98,100Mo and 100,102Ru targets. The deduced nucleon occupancies reveal significant discrepancies when compared with theoretical calculations; the same calculations have previously been used to determine the nuclear matrix element associated with the decay probability of double {\beta} decay of the 100Mo system.Comment: 18 pages, 13 figures, 37 pages of supplemental informatio

High-Transconductance Graphene Solution-Gated Field Effect Transistors

In this work, we report on the electronic properties of solution-gated field effect transistors (SGFETs) fabricated using large-area graphene. Devices prepared both with epitaxially grown graphene on SiC as well as with chemical vapor deposition grown graphene on Cu exhibit high transconductances, which are a consequence of the high mobility of charge carriers in graphene and the large capacitance at the graphene/water interface. The performance of graphene SGFETs, in terms of gate sensitivity, is compared to other SGFET technologies and found to be clearly superior, confirming the potential of graphene SGFETs for sensing applications in electrolytic environments.Comment: The following article has been submitted to Applied Physics Letters. After it is published, it will be found at apl.aip.or

Comment on the paper, "the reaction of nitric oxide with atomic nitrogen as a possible excitation source of auroral green une"

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22021/1/0000437.pd

Hydrogen Incorporation in Natural Mantle Olivines

Constraints on water storage capacity and actual content in the mantle must be derived not only from experimental studies, but also from investigation of natural samples. Olivine is one of the best-studied, OH-bearing "nominally anhydrous" minerals, yet there remain multiple hypotheses for the incorporation mechanism of hydrogen in this phase. Moreover, there is still debate as to whether the mechanism is the same in natural samples vs. experimental studies, where concentrations can reach very high values (up to ~0.6 wt% H_2O) at high pressures and temperatures. We present new observations and review IR and TEM data from the literature that bear on this question. Hydrogen incorporation in natural olivine clearly occurs by multiple mechanisms, but in contrast to some previous assertions we find that there are strong similarities between the IR signatures of experimentally annealed olivines and most natural samples. At low pressures (lower than ~2 GPa) in both experiments and natural olivines, hydrogen incorporation might be dominated by a humite-type defect, but the nature of the defect may vary even within a single sample; possibilities include point defects, planar defects and optically detectable inclusions. IR bands between 3300 and 3400 cm^(-1), ascribed previously to the influence of silica activity, are apparently related instead to increased oxygen fugacity. At higher pressures in experiments, the IR band structure changes and hydrogen is probably associated with disordered point defects. Similar IR spectra are seen in olivines from xenoliths derived from deeper parts of the mantle (below South Africa and the Colorado Plateau) as well as in olivines from the ultra-high pressure metamorphic province of the Western Gneiss Region in Norway