Hydrologic-economic Feasibility Study on Precipitation Augmentation Over the Great Lakes

published or submitted for publicationis peer reviewedOpe

Gravitational Collapse in One Dimension

We simulate the evolution of one-dimensional gravitating collisionless systems from non- equilibrium initial conditions, similar to the conditions that lead to the formation of dark- matter halos in three dimensions. As in the case of 3D halo formation we find that initially cold, nearly homogeneous particle distributions collapse to approach a final equilibrium state with a universal density profile. At small radii, this attractor exhibits a power-law behavior in density, {\rho}(x) \propto |x|^(-{\gamma}_crit), {\gamma}_crit \simeq 0.47, slightly but significantly shallower than the value {\gamma} = 1/2 suggested previously. This state develops from the initial conditions through a process of phase mixing and violent relaxation. This process preserves the energy ranks of particles. By warming the initial conditions, we illustrate a cross-over from this power-law final state to a final state containing a homogeneous core. We further show that inhomogeneous but cold power-law initial conditions, with initial exponent {\gamma}_i > {\gamma}_crit, do not evolve toward the attractor but reach a final state that retains their original power-law behavior in the interior of the profile, indicating a bifurcation in the final state as a function of the initial exponent. Our results rely on a high-fidelity event-driven simulation technique.Comment: 14 Pages, 13 Figures. Submitted to MNRA

The Importance of Gender and Readiness to Change in the Prediction of Drinking and Negative Consequences of First-Year Student Drinkers

College drinking is widespread, and binge drinkers can experience serious consequences. The present study examined the effectiveness of two interventions, expressive writing and behavioral monitoring, as well a combined condition, in reducing drinking and negative consequences associated with drinking. Gender differences and differences in readiness to change binge drinking were also assessed. Participants (N = 97) completed a pretest, eight weekly intervention activities, and a posttest during their first semester of college. An ANOVA tested the hypothesis that individuals higher in readiness to change binge drinking participated in more of the weekly intervention activities; this hypothesis was not supported. A series of multiple regressions examined the hypotheses that after controlling for negative consequences, readiness to change and gender would be related to typical drinking (average and heavy) at pretest and posttest. Negative consequences and being in precontemplation predicted pretest drinking, and being in precontemplation predicted posttest drinking. A series of mixed randomizedrepeated measures ANOVAs assessed whether typical drinking (average and heavy) and negative consequences changed from pretest to posttest based on intervention group, gender, and readiness to change binge drinking. While the main hypotheses were not supported, results revealed that drinking remained the same from pretest to posttest; males reported more drinking than females; individuals in precontemplation tended to report the most drinking and negative consequences; and overall, negative consequences from drinking increased from pretest to posttest. A hierarchical linear model (ef) was tested using pretest readiness to change, gender, and intervention condition to predict drinking over the eight-week intervention. Males and precontemplators reported the most initial drinking. Over time, participants in the expressive writing condition tended to increase their drinking over the course of the semester, while males in the monitoring condition tended to decrease their drinking. The present study contributes a greater understanding of readiness to change binge drinking and an assessment of the interventions\u27 ability to reduce drinking and negative consequences among first-year students. The findings will help researchers identify individuals interested in reducing their binge drinking and will be of interest to college personnel who desire to address college drinking early in students\u27 college experienc

H2 molecule in strong magnetic fields

The Pauli-Hamiltonian of a molecule with fixed nuclei in a strong constant magnetic field is asymptotic, in norm-resolvent sense, to an effective Hamiltonian which has the form of a multi-particle Schr\"odinger operator with interactions given by one-dimensional \delta-potentials. We study this effective Hamiltonian in the case of the H2 -molecule and establish existence of the ground state. We also show that the inter-nuclear equilibrium distance tends to 0 as the field-strength tends to infinity

Gamma Rays from Star Formation in Clusters of Galaxies

Star formation in galaxies is observed to be associated with gamma-ray emission. The detection of gamma rays from star-forming galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation rate and gamma-ray luminosity (Ackermann et. al. 2012). Since star formation is known to scale with total infrared (8-1000 micrometers) and radio (1.4 GHz) luminosity, the observed infrared and radio emission from a star-forming galaxy can be used to quantitatively infer the galaxy's gamma-ray luminosity. Similarly, star forming galaxies within galaxy clusters allow us to derive lower limits on the gamma-ray emission from clusters, which have not yet been conclusively detected in gamma rays. In this study we apply the relationships between gamma-ray luminosity and radio and IR luminosities derived in Ackermann et. al. 2012 to a sample of galaxy clusters from Ackermann et. al. 2010 in order to place lower limits on the gamma-ray emission associated with star formation in galaxy clusters. We find that several clusters have predicted lower limits on gamma-ray emission that are within an order of magnitude of the upper limits derived in Ackermann et. al. 2010 based on non-detection by Fermi-LAT. Given the current gamma-ray limits, star formation likely plays a significant role in the gamma-ray emission in some clusters, especially those with cool cores. We predict that both Fermi-LAT over the course of its lifetime and the future Cherenkov Telescope Array will be able to detect gamma-ray emission from star-forming galaxies in clusters.Comment: 17 pages, 2 figures, 2 tables. Minor revisions made to match version accepted to Ap

Uncovering temporal structure in hippocampal output patterns.

Place cell activity of hippocampal pyramidal cells has been described as the cognitive substrate of spatial memory. Replay is observed during hippocampal sharp-wave-ripple-associated population burst events (PBEs) and is critical for consolidation and recall-guided behaviors. PBE activity has historically been analyzed as a phenomenon subordinate to the place code. Here, we use hidden Markov models to study PBEs observed in rats during exploration of both linear mazes and open fields. We demonstrate that estimated models are consistent with a spatial map of the environment, and can even decode animals' positions during behavior. Moreover, we demonstrate the model can be used to identify hippocampal replay without recourse to the place code, using only PBE model congruence. These results suggest that downstream regions may rely on PBEs to provide a substrate for memory. Additionally, by forming models independent of animal behavior, we lay the groundwork for studies of non-spatial memory

The Azimuthal Asymmetry at large p_t seem to be too large for a ``Jet Quenching''

We discuss simple generic model of ``jet quenching'' in which matter absorption is defined by one parameter. We show that as absorption grows, the azimuthal asymmetry v_2 grows as well, reaching the finite limit with a simple geometric interpretation. It turns out, that this limit is still below the experimental values for 6 > p_t > 2 GeV, according to preliminary data from STAR experiment at RHIC. We thus conclude that ``jet quenching'' models alone cannot account for the observed phenomenon, and speculate about alternative scenarios.Comment: 3 pages, 2 figs, 1 table. The final version contaning note added in proofs for PRC, which reflects experimental development which seem to suggest that the geometrical model for v2 is in fact correct description of data at pt=2-10 Ge

454-Pyrosequencing: A Molecular Battiscope for Freshwater Viral Ecology

Viruses, the most abundant biological entities on the planet, are capable of infecting organisms from all three branches of life, although the majority infect bacteria where the greatest degree of cellular diversity lies. However, the characterization and assessment of viral diversity in natural environments is only beginning to become a possibility. Through the development of a novel technique for the harvest of viral DNA and the application of 454 pyrosequencing, a snapshot of the diversity of the DNA viruses harvested from a standing pond on a cattle farm has been obtained. A high abundance of viral genotypes (785) were present within the virome. The absolute numbers of lambdoid and Shiga toxin (Stx) encoding phages detected suggested that the depth of sequencing had enabled recovery of only ca. 8% of the total virus population, numbers that agreed within less than an order of magnitude with predictions made by rarefaction analysis. The most abundant viral genotypes in the pond were bacteriophages (93.7%). The predominant viral genotypes infecting higher life forms found in association with the farm were pathogens that cause disease in cattle and humans, e.g. members of the Herpesviridae. The techniques and analysis described here provide a fresh approach to the monitoring of viral populations in the aquatic environment, with the potential to become integral to the development of risk analysis tools for monitoring the dissemination of viral agents of animal, plant and human diseases

Spectroscopically orthogonal labelling to disentangle site-specific nitroxide label distributions

Funding: The authors acknowledge support by the Wellcome Trust (204821/Z/16/Z), the Leverhulme Trust (RPG-2018-397), and the EPSRC (EP/X016455/1). BEB acknowledges equipment funding by BBSRC (BB/R013780/1 and BB/T017740/1).Biomolecular applications of pulse dipolar electron paramagnetic resonance spectroscopy (PDS) are becoming increasingly valuable in structural biology. Site-directed spin labelling of proteins is routinely performed using nitroxides, with paramagnetic metal ions and other organic radicals gaining popularity as alternative spin centres. Spectroscopically orthogonal spin labelling using different types of labels potentially increases the information content available from a single sample. When analysing experimental distance distributions between two nitroxide spin labels, the site-specific rotamer information has been projected into the distance and is not readily available, and the contributions of individual labelling sites to the width of the distance distribution are not obvious from the PDS data. Here, we exploit the exquisite precision of labelling double-histidine (dHis) motifs with CuII chelate complexes. The contribution of this label to the distance distribution widths in model protein GB1 has been shown to be negligible. By combining a dHis CuII labelling site with cysteine-specific nitroxide labelling, we gather insights on the label rotamers at two distinct sites, comparing their contributions to distance distributions based on different in silico modelling approaches and structural models. From this study, it seems advisable to consider discrepancies between different in silico modelling approaches when selecting labelling sites for PDS studies.Publisher PDFPeer reviewe

Gamma Ray Bursts: recent results and connections to very high energy Cosmic Rays and Neutrinos

Gamma-ray bursts are the most concentrated explosions in the Universe. They have been detected electromagnetically at energies up to tens of GeV, and it is suspected that they could be active at least up to TeV energies. It is also speculated that they could emit cosmic rays and neutrinos at energies reaching up to the $10^{18}-10^{20}$ eV range. Here we review the recent developments in the photon phenomenology in the light of \swift and \fermi satellite observations, as well as recent IceCube upper limits on their neutrino luminosity. We discuss some of the theoretical models developed to explain these observations and their possible contribution to a very high energy cosmic ray and neutrino background.Comment: 12 pages, 7 figures. Text of a plenary lecture at the PASCOS 12 conference, Merida, Yucatan, Mexico, June 2012; to appear in J.Phys. (Conf. Series