The Effect of Zonally Asymmetric Ozone Heating on the Northern Hemisphere Winter Polar Stratosphere

[1] Previous modeling studies have found significant differences in winter extratropical stratospheric temperatures depending on the presence or absence of zonally asymmetric ozone heating (ZAOH), yet the physical mechanism causing these differences has not been fully explained. The present study describes the effect of ZAOH on the dynamics of the Northern Hemisphere extratropical stratosphere using an ensemble of free-running atmospheric general circulation model simulations over the 1 December - 31 March period. We find that the simulations including ZAOH produce a significantly warmer and weaker stratospheric polar vortex in mid-February due to more frequent major stratospheric sudden warmings compared to the simulations using only zonal mean ozone heating. This is due to regions of enhanced Eliassen-Palm flux convergence found in the region between 40°N–70°N latitude and 10–0.05 hPa. These results are consistent with changes in the propagation of planetary waves in the presence of ZAOH predicted by an ozone-modified refractive index

Fluorescent amplification for next generation sequencing (FA-NGS) library preparation.

BACKGROUND:Next generation sequencing (NGS) has become a universal practice in modern molecular biology. As the throughput of sequencing experiments increases, the preparation of conventional multiplexed libraries becomes more labor intensive. Conventional library preparation typically requires quality control (QC) testing for individual libraries such as amplification success evaluation and quantification, none of which occur until the end of the library preparation process. RESULTS:In this study, we address the need for a more streamlined high-throughput NGS workflow by tethering real-time quantitative PCR (qPCR) to conventional workflows to save time and implement single tube and single reagent QC. We modified two distinct library preparation workflows by replacing PCR and quantification with qPCR using SYBR Green I. qPCR enabled individual library quantification for pooling in a single tube without the need for additional reagents. Additionally, a melting curve analysis was implemented as an intermediate QC test to confirm successful amplification. Sequencing analysis showed comparable percent reads for each indexed library, demonstrating that pooling calculations based on qPCR allow for an even representation of sequencing reads. To aid the modified workflow, a software toolkit was developed and used to generate pooling instructions and analyze qPCR and melting curve data. CONCLUSIONS:We successfully applied fluorescent amplification for next generation sequencing (FA-NGS) library preparation to both plasmids and bacterial genomes. As a result of using qPCR for quantification and proceeding directly to library pooling, the modified library preparation workflow has fewer overall steps. Therefore, we speculate that the FA-NGS workflow has less risk of user error. The melting curve analysis provides the necessary QC test to identify and troubleshoot library failures prior to sequencing. While this study demonstrates the value of FA-NGS for plasmid or gDNA libraries, we speculate that its versatility could lead to successful application across other library types

Fluid Elasticity Can Enable Propulsion at Low Reynolds Number

Conventionally, a microscopic particle that performs a reciprocal stroke cannot move through its environment. This is because at small scales, the response of simple Newtonian fluids is purely viscous and flows are time-reversible. We show that by contrast, fluid elasticity enables propulsion by reciprocal forcing that is otherwise impossible. We present experiments on rigid objects actuated reciprocally in viscous fluids, demonstrating for the first time a purely elastic propulsion set by the object's shape and boundary conditions. We describe two different artificial "swimmers" that experimentally realize this principle.Comment: 5 pages, 4 figure

Role of coronal mass ejections in the heliospheric Hale cycle

[1] The 11-year solar cycle variation in the heliospheric magnetic field strength can be explained by the temporary buildup of closed flux released by coronal mass ejections (CMEs). If this explanation is correct, and the total open magnetic flux is conserved, then the interplanetary-CME closed flux must eventually open via reconnection with open flux close to the Sun. In this case each CME will move the reconnected open flux by at least the CME footpoint separation distance. Since the polarity of CME footpoints tends to follow a pattern similar to the Hale cycle of sunspot polarity, repeated CME eruption and subsequent reconnection will naturally result in latitudinal transport of open solar flux. We demonstrate how this process can reverse the coronal and heliospheric fields, and we calculate that the amount of flux involved is sufficient to accomplish the reversal within the 11 years of the solar cycle

Update on Radiation Dose From Galactic and Solar Protons at the Moon Using the LRO/CRaTER Microdosimeter

The NASA Lunar Reconnaissance Orbiter (LRO) has been exploring the lunar surface and radiation environment since June 2009. In Mazur et al. [2011] we discussed the first 6 months of mission data from a microdosimeter that is housed within the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument onboard LRO. The CRaTER microdosimeter is an early version of what is now a commercially available hybrid that accurately measures total ionizing radiation dose in a silicon target (http://www.teledynemicro.com/product/radiation-dosimeter). This brief report updates the transition from a deep solar minimum radiation environment to the current weak solar maximum as witnessed with the microdosimeter

Neutral Hydrogen Mapping of Virgo Cluster Blue Compact Dwarf Galaxies

A new installment of neutral hydrogen mappings of Blue Compact Dwarf galaxies, as defined by optical morphology, in and near the Virgo cluster is presented. The primary motivation was to search for outlying clouds of HI as potential interactive triggers of the enhanced star formation, and therefore the mapped galaxies were selected for large HI} mass, large optical diameter, and large velocity profile width. Approximately half the sample proved to have one or more small, low column density star-free companion clouds, either detached or appearing as an appendage in our maps, at resolution of order 4 kpc. Comparison is made to a sample of similarly mapped field BCD galaxies drawn from the literature; however, the Virgo cluster sample of mapped BCDs is still too small for conclusive comparisons to be made. We found, on the one hand, little or no evidence for ram pressure stripping nor, on the other, for extremely extended low column density HI envelopes. The HI rotation curves in most cases rise approximately linearly, and slowly, as far out as we can trace the gas.Comment: To appear in AJ, Dec. 200

Deep dielectric charging of regolith within the Moon\u27s permanently shadowed regions

Abstract Energetic charged particles, such as galactic cosmic rays (GCRs) and solar energetic particles (SEPs), can penetrate deep within the lunar surface, resulting in deep dielectric charging. This charging process depends on the GCR and SEP currents, as well as on the regolith\u27s electrical conductivity and permittivity. In permanently shadowed regions (PSRs) near the lunar poles, the discharging timescales are on the order of a lunation (∼20 days). We present the first predictions for deep dielectric charging of lunar regolith. To estimate the resulting subsurface electric fields, we develop a data-driven, one-dimensional, time-dependent model. For model inputs, we use GCR data from the Cosmic Ray Telescope for the Effects of Radiation on board the Lunar Reconnaissance Orbiter and SEP data from the Electron, Proton, and Alpha Monitor on the Advanced Composition Explorer. We find that during the recent solar minimum, GCRs create persistent electric fields up to ∼700 V/m. We also find that large SEP events create transient but strong electric fields (≥106 V/m) that may induce dielectric breakdown. Such breakdown would likely result in significant modifications to the physical and chemical properties of the lunar regolith within PSRs. Key Points Energetic charged particles deep dielectrically charge the lunar regolithWe model the resulting subsurface electric fieldsThe electric fields may be great enough to induce dielectric breakdown

The radiation environment near the lunar surface: CRaTER observations and Geant4 simulations

[1] At the start of the Lunar Reconnaissance Orbiter mission in 2009, its Cosmic Ray Telescope for the Effects of Radiation instrument measured the radiation environment near the Moon during the recent deep solar minimum, when galactic cosmic rays (GCRs) were at the highest level observed during the space age. We present observations that show the combined effects of GCR primaries, secondary particles (“albedo”) created by the interaction of GCRs with the lunar surface, and the interactions of these particles in the shielding material overlying the silicon solid-state detectors of the Cosmic Ray Telescope for the Effects of Radiation. We use Geant4 to model the energy and angular distribution of the albedo particles, and to model the response of the sensor to the various particle species reaching the 50 kilometer altitude of the Lunar Reconnaissance Orbiter. Using simulations to gain insight into the observations, we are able to present preliminary energy-deposit spectra for evaluation of the radiation environment\u27s effects on other sensitive materials, whether biological or electronic, that would be exposed to a similar near-lunar environment