Nonlinear electrophoresis in the presence of dielectric decrement

The nonlinear phenomena that occur in the electric double layer (EDL) that forms at charged surfaces strongly influence electrokinetic effects, including electro-osmosis and electrophoresis. In particular, saturation effects due to either dielectric decrement or ion crowding effects are of paramount importance. Dielectric decrement significantly influences the ionic concentration in the EDL at high ζ potential, leading to the formation of a condensed layer near the particle's surface. In this article, we present a model incorporating both steric effects due to the finite size of ions and dielectric decrement to describe the physics in the electric double layer. The model remains valid in both weakly and strongly nonlinear regimes, as long as the electric double layer remains in quasiequilibrium. We apply this model to the study of two archetypal problems in electrokinetics, namely the electrophoresis of particles with fixed surface charges and the electrophoresis of ideally polarizable particles

Revision of world Sphecomyia Latreille (Diptera, Syrphidae)

The 16 world species of Sphecomyia Latreille are revised, including seven previously undescribed species (S. cryptica Moran, sp. n., S. hoguei Moran, sp. n., S. interrupta Moran, sp. n., S. oraria Moran, sp. n., S. pseudosphecomima Moran, sp. n., S. sexfasciata Moran, sp. n., and S. weismani Moran, sp. n.). Descriptions, redescriptions, male genitalia photographs, distribution maps, and an illustrated key for all Sphecomyia are presented. DNA barcode data are provided for all 16 species with a cytochrome oxidase subunit I gene tree presented and discussed. Sphecomyia stat. rev. is redefined to represent the monophyletic lineage of species within subtribe Criorhinina possessing a bare, medial vitta extending ventrally from the oral margin in both sexes, a bare gena, a bare katepimeron, a scutellum with at least anterior margin densely pruinose, an anterior ventral half of vein C before crossvein h without setae, and a narrow intersection of vein R1 with vein C. Three species groups of Sphecomyia are identified: the S. vittata group which possess pruinose scutellar vittae, the S. pattonii group which lack pruinose scutellar vittae, and S. metallica (Bigot), a hairy bee mimic with a completely pruinose scutum. Criorhina tsherepanovi Violovitsh is resurrected and transferred, along with Criorhina aino Stackelberg, to the genus Sphecomyia: S. tsherepanovi (Violovitsh), comb. n. and S. aino (Stackelberg), comb. n. Criorhina metallica (Bigot) is designated as the senior synonym of C. lupina (Williston), not junior as improperly treated, and transferred to Sphecomyia: S. metallica (Bigot), comb. n. The species Sphecomyia fusca Weisman, S. nasica Osburn, and S. occidentalis Osburn are transferred to Criorhina Meigen: C. fusca (Weisman), comb. n., C. nasica (Osburn), comb. n., and C. occidentalis (Osburn), comb. n

Monohydroxylated metabolites of the K2 synthetic cannabinoid JWH-073 retain intermediate to high cannabinoid 1 receptor (CB1R) affinity and exhibit neutral antagonist to partial agonist activity

K2 and several similar purported “incense products” spiked with synthetic cannabinoids are abused as cannabis substitutes. We hypothesized that metabolism of JWH-073, a prevalent cannabinoid found in K2, contributes to toxicity associated with K2 use. Competition receptor binding studies and G-protein activation assays, both performed by employing mouse brain homogenates, were used to determine the affinity and intrinsic activity, respectively, of potential monohydroxylated (M1, M3–M5) and monocarboxylated (M6) metabolites at cannabinoid 1 receptors (CB1Rs). Surprisingly, M1, M4 and M5 retain nanomolar affinity for CB1Rs, while M3 displays micromolar affinity and M6 does not bind to CB1Rs. JWH-073 displays equivalent efficacy to that of the CB1R full agonist CP-55,940, while M1, M3, and M5 act as CB1R partial agonists, and M4 shows little or no intrinsic activity. Further in vitro investigation by Schild analysis revealed that M4 acts as a competitive neutral CB1R antagonist (Kb~40nM). In agreement with in vitro studies, M4 also demonstrates CB1R antagonism in vivo by blunting cannabinoid-induced hypothermia in mice. Interestingly, M4 does not block agonist-mediated responses of other measures in the cannabinoid tetrad (e.g., locomotor suppression, catalepsy or analgesia). Finally, also as predicted by in vitro results, M1 exhibits agonist activity in vivo by inducing significant hypothermia and suppression of locomotor activity in mice. In conclusion, the present study indicates that further work examining the physiological effects of synthetic cannabinoid metabolism is warranted. Such a complex mix of metabolically produced CB1R ligands may contribute to the adverse effect profile of JWH-073-containing products

Bayesian Learning of Gas Transport in Three-Dimensional Fracture Networks

Modeling gas flow through fractures of subsurface rock is a particularly challenging problem because of the heterogeneous nature of the material. High-fidelity simulations using discrete fracture network (DFN) models are one methodology for predicting gas particle breakthrough times at the surface, but are computationally demanding. We propose a Bayesian machine learning method that serves as an efficient surrogate model, or emulator, for these three-dimensional DFN simulations. Our model trains on a small quantity of simulation data and, using a graph/path-based decomposition of the fracture network, rapidly predicts quantiles of the breakthrough time distribution. The approach, based on Gaussian Process Regression (GPR), outputs predictions that are within 20-30% of high-fidelity DFN simulation results. Unlike previously proposed methods, it also provides uncertainty quantification, outputting confidence intervals that are essential given the uncertainty inherent in subsurface modeling. Our trained model runs within a fraction of a second, which is considerably faster than other methods with comparable accuracy and multiple orders of magnitude faster than high-fidelity simulations

A multigene phylogeny of the eristaline flower flies (Diptera : Syrphidae), with emphasis on the subtribe Criorhinina

We present the first multigene phylogeny focused on Eristalinae (Diptera: Syrphidae) utilizing a dataset containing 120 flower fly species from across all four subfamilies and representing 13 out of 16 tribes. Eight genes were used in the construction of the phylogeny: mitochondrial cytochrome c oxidase subunit I and the nuclear genes 28S ribosomal DNA, Alanylt RNA Synthetase, the carbamoyl phosphate synthase domain of CAD, Period, RNA-binding Protein 15 (RBP-15, 5'), Casein Kinase 1 and TULP for a total of similar to 6.7 kB of data. Eristalinae is recovered as paraphyletic with strong support for the elevation of Cerioidini, Merodontini and Volucellini to subfamilial status. Deineches, Flukea and Malometasternum render Criorhinina paraphyletic with respect to the type genus Criorhina. A clade with Criorhina, Matsumyia and Sphecomyia is strongly supported. The generic concept of Criorhina is paraphyletic, while Sphecomyia is monophyletic and Matsumyia is monophyletic but requires expansion. Evidence supports the resurrection of Romaleosyrphus and the creation of new genera. Criorhinina (stat. rev.) is restricted to contain Criorhina, Matsumyia, Romaleosyrphus and Sphecomyia. Thirteen changes to the higher classification of Syrphidae are proposed.Peer reviewe

The Stellar Populations of Stripped Spiral Galaxies in the Virgo Cluster

(Abridged) We present an analysis of the stellar populations of the gas-stripped outer disks of ten Virgo Cluster spiral galaxies, utilizing SparsePak integral field spectroscopy on the WIYN 3.5m telescope and GALEX UV photometry. The galaxies in our sample show evidence for being gas-stripped spiral galaxies, with star formation within a truncation radius, and a passive population beyond the truncation radius. We find that all of the galaxies with spatially truncated star formation have outer disk stellar populations consistent with star formation ending within the last 500 Myr. The synthesis of optical spectroscopy and GALEX observations demonstrate that star formation was relatively constant until the quenching time, after which the galaxies passively evolved. Large starbursts at the time of quenching are excluded for all galaxies. For approximately half of our galaxies, timescales derived from our observations are consistent with galaxies being stripped in or near the cluster core, where simple ram-pressure estimates can explain the stripping. However, the other half of our sample galaxies were clearly stripped outside the cluster core. Such galaxies provide evidence that the intra-cluster medium is not static and smooth. For three of our sample galaxies, our stripping timescales agree with those from the gas stripping simulations, suggesting that star formation is quenched near the time of peak pressure. While the stripping of star-forming gas in the outer disk creates a passive population in our galaxies, there is still normal star formation in the center of our sample galaxies. It may be that Virgo is not massive enough to completely strip these spiral galaxies and, in a more dynamically active cluster or a cluster with a higher density ICM, such a process would lead to passive spirals and/or S0s.Comment: 17 pages, 19 figures, accepted for publication in AJ. Replaced submission corrects Table names and matches figure style of Journal articl

Systematics and evolution of predatory flower flies (Diptera Syrphidae) based on exon-capture sequencing

Flower flies (Diptera: Syrphidae) are one of the most species-rich dipteran families and provide important ecosystem services such as pollination, biological control of pests, recycling of organic matter and redistributions of essential nutrients. Flower fly adults generally feed on pollen and nectar, but their larval feeding habits are strikingly diverse. In the present study, high-throughput sequencing was used to capture and enrich phylogenetically and evolutionary informative exonic regions. With the help of the baitfisher software, we developed a new bait kit (SYRPHIDAE1.0) to target 1945 CDS regions belonging to 1312 orthologous genes. This new bait kit was successfully used to exon capture the targeted loci in 121 flower fly species across the different subfamilies of Syrphidae. We analysed different amino acid and nucleotide data sets (1302 loci and 154 loci) with maximum likelihood and multispecies coalescent models. Our analyses yielded highly supported similar topologies, although the degree of the SRH (global stationarity, reversibility and homogeneity) conditions varied greatly between amino acid and nucleotide data sets. The sisterhood of subfamilies Pipizinae and Syrphinae is supported in all our analyses, confirming a common origin of taxa feeding on soft-bodied arthropods. Based on our results, we define Syrphini stat.rev. to include the genera Toxomerus and Paragus. Our divergence estimate analyses with beast inferred the origin of the Syrphidae in the Lower Cretaceous (125.5-98.5 Ma) and the diversification of predatory flower flies around the K-Pg boundary (70.61-54.4 Ma), coinciding with the rise and diversification of their prey.Peer reviewe

Caught in the Act: Strong, Active Ram Pressure Stripping in Virgo Cluster Spiral NGC 4330

We present a multi-wavelength study of NGC 4330, a highly-inclined spiral galaxy in the Virgo Cluster which is a clear example of strong, ongoing ICM-ISM ram pressure stripping. The HI has been removed from well within the undisturbed old stellar disk, to 50% - 65% of R_25. Multi-wavelength data (WIYN BVR and H-alpha, VLA 21-cm HI and radio continuum, and GALEX NUV and FUV) reveal several one-sided extraplanar features likely caused by ram pressure at an intermediate disk-wind angle. At the leading edge of the interaction, the H-alpha and dust extinction curve sharply out of the disk in a remarkable and distinctive "upturn" feature that may be generally useful as a diagnostic indicator of active ram pressure. On the trailing side, the ISM is stretched out in a long tail which contains 10% of the galaxy's total HI emission, 6 - 9% of its NUV-FUV emission, but only 2% of the H-alpha. The centroid of the HI tail is downwind of the UV/H-alpha tail, suggesting that the ICM wind has shifted most of the ISM downwind over the course of the past 10 - 300 Myr. Along the major axis, the disk is highly asymmetric in the UV, but more symmetric in H-alpha and HI, also implying recent changes in the distributions of gas and star formation. The UV-optical colors indicate very different star formation histories for the leading and trailing sides of the galaxy. On the leading side, a strong gradient in the UV-optical colors of the gas-stripped disk suggests that it has taken 200-400 Myr to strip the gas from a radius of >8 to 5 kpc, but on the trailing side there is no age gradient. All our data suggest a scenario in which NGC 4330 is falling into cluster center for first time and has experienced a significant increase in ram pressure over the last 200-400 Myr.Comment: AJ accepted; 22 pages, 25 figures, version with full-resolution figures available at http://www.astro.yale.edu/abramso

Selection against Spurious Promoter Motifs Correlates with Translational Efficiency across Bacteria

Because binding of RNAP to misplaced sites could compromise the efficiency of transcription, natural selection for the optimization of gene expression should regulate the distribution of DNA motifs capable of RNAP-binding across the genome. Here we analyze the distribution of the −10 promoter motifs that bind the σ70 subunit of RNAP in 42 bacterial genomes. We show that selection on these motifs operates across the genome, maintaining an over-representation of −10 motifs in regulatory sequences while eliminating them from the nonfunctional and, in most cases, from the protein coding regions. In some genomes, however, −10 sites are over-represented in the coding sequences; these sites could induce pauses effecting regulatory roles throughout the length of a transcriptional unit. For nonfunctional sequences, the extent of motif under-representation varies across genomes in a manner that broadly correlates with the number of tRNA genes, a good indicator of translational speed and growth rate. This suggests that minimizing the time invested in gene transcription is an important selective pressure against spurious binding. However, selection against spurious binding is detectable in the reduced genomes of host-restricted bacteria that grow at slow rates, indicating that components of efficiency other than speed may also be important. Minimizing the number of RNAP molecules per cell required for transcription, and the corresponding energetic expense, may be most relevant in slow growers. These results indicate that genome-level properties affecting the efficiency of transcription and translation can respond in an integrated manner to optimize gene expression. The detection of selection against promoter motifs in nonfunctional regions also confirms previous results indicating that no sequence may evolve free of selective constraints, at least in the relatively small and unstructured genomes of bacteria