Feedback and its Feedback Effect on Feedback: Photoionization Suppression and its Impact on Galactic Outflows

We show that radiative feedback due to reionization has a pronounced effect on the extent of mechanical feedback due to galactic outflows. The photoionization of the Intergalactic Medium (IGM) suppresses low-mass galaxy formation by photoheating the gas and limiting atomic line cooling. The number of low-mass galaxies is central for the enrichment of the IGM as these objects have the capacity to enrich a significant fraction (by volume) of the Universe. We use a modified version of our galactic outflow model, combined with a simple criterion for suppression, to investigate the potential impact upon the IGM. We find that this suppression strongly reduces the enrichment of the IGM and is sensitive to the reionization history. We also investigate the contribution of halos of different masses with varying degrees of suppression.Comment: 4 pages, 3 figures, class file included, accepted by ApJ Letters, minor changes and expanded Figure

Anisotropic Outflows and IGM Enrichment

We have designed an analytical model for the evolution of anisotropic galactic outflows. These outflows follow the path of least resistance, and thus travel preferentially into low-density regions, away from cosmological structures where galaxies form. We show that anisotropic outflows can significantly enrich low-density systems with metals.Comment: Proceedings of Chemodynamics 2006, Lyon, 2 pages, 1 figure, style file include

Description of the inelastic collision of two solitary waves for the BBM equation

We prove that the collision of two solitary waves of the BBM equation is inelastic but almost elastic in the case where one solitary wave is small in the energy space. We show precise estimates of the nonzero residue due to the collision. Moreover, we give a precise description of the collision phenomenon (change of size of the solitary waves).Comment: submitted for publication. Corrected typo in Theorem 1.

Dynamics of a hyperbolic system that applies at the onset of the oscillatory instability

A real hyperbolic system is considered that applies near the onset of the oscillatory instability in large spatial domains. The validity of that system requires that some intermediate scales (large compared with the basic wavelength of the unstable modes but small compared with the size of the system) remain inhibited; that condition is analysed in some detail. The dynamics associated with the hyperbolic system is fully analysed to conclude that it is very simple if the coefficient of the cross-nonlinearity is such that , while the system exhibits increasing complexity (including period-doubling sequences, quasiperiodic transitions, crises) as the bifurcation parameter grows if ; if then the system behaves subcritically. Our results are seen to compare well, both qualitatively and quantitatively, with the experimentally obtained ones for the oscillatory instability of straight rolls in pure Rayleigh - Bénard convection

Anisotropic Galactic Outflows and Enrichment of the Intergalactic Medium. I: Monte Carlo Simulations

We have developed an analytical model to describe the evolution of anisotropic galactic outflows. With it, we investigate the impact of varying opening angle on galaxy formation and the evolution of the IGM. We have implemented this model in a Monte Carlo algorithm to simulate galaxy formation and outflows in a cosmological context. Using this algorithm, we have simulated the evolution of a comoving volume of size [12h^(-1)Mpc]^3 in the LCDM universe. Starting from a Gaussian density field at redshift z=24, we follow the formation of ~20,000 galaxies, and simulate the galactic outflows produced by these galaxies. When these outflows collide with density peaks, ram pressure stripping of the gas inside the peak may result. This occurs in around half the cases and prevents the formation of galaxies. Anisotropic outflows follow the path of least resistance, and thus travel preferentially into low-density regions, away from cosmological structures (filaments and pancakes) where galaxies form. As a result, the number of collisions is reduced, leading to the formation of a larger number of galaxies. Anisotropic outflows can significantly enrich low-density systems with metals. Conversely, the cross-pollution in metals of objects located in a common cosmological structure, like a filament, is significantly reduced. Highly anisotropic outflows can travel across cosmological voids and deposit metals in other, unrelated cosmological structures.Comment: 32 pages, 9 figures (2 color). Revised version accepted in Ap

Using environmental DNA and occupancy modeling to estimate rangewide metapopulation dynamics of the endangered tidewater goby eucyclogobius spp.

Conservation of species is most effective when metapopulation dynamics are well understood and incorporated into management plans, allowing managers to target conservation efforts where they will be most effective. The development of environmental DNA (eDNA) methods provides an efficient and highly sensitive approach to generate presence and absence data needed to elucidate metapopulation dynamics. Combining sample detection histories from eDNA surveys with occupancy models that account for non-detection can offer unbiased estimates of rangewide metapopulation dynamics. However, traditional occupancy models do not allow direct evaluation of the drivers of site occupancy, extinction, and colonization. Herein, I utilize a novel dynamic multiscale occupancy model that accounts for non-detection to estimate rangewide metapopulation dynamics and their drivers in an endangered fish, tidewater goby Eucyclogobius spp., a genus endemic to California estuarine habitats. I collected rangewide eDNA data from 190 sites (813 total water samples) surveyed from two years (2016 and 2017) and analyzed the data using a dynamic multiscale occupancy model. Rangewide, estimates of the proportion of sites that were occupied varied little between 2016 (0.524) and 2017 (0.517). Although I uncovered stability in the number of sites that were occupied across the two study years, there was evidence for extinction and colonization dynamics. Rangewide estimates of extinction probability of occupied sites (0.106) and colonization probability of unoccupied sites (0.085) were nearly equal. The consistent rangewide occupancy proportions combined with the presence of extinctions and colonization suggests a dynamic equilibrium between the two years surveyed. There was no latitudinal gradient or regional differences in extinction and colonization dynamics across the tidewater goby geographic range. Assessment of covariate effects on metapopulation dynamics revealed that colonization probability increased as the number of occupied neighboring sites increased and as distance between occupied sites decreased. I show that eDNA surveys can rapidly provide a snapshot of a species distribution over a broad geographic range, and when these surveys are paired with dynamic multiscale occupancy modeling, they can uncover rangewide and regional scale metapopulation dynamics and their drivers

Nota preliminar sobre la estratigrafía de la facies de Fuencaliente (Cuenca-Valencia)

Se sintetizan las principales características del Neógeno continental (facies de Fuencaliente) de los limites de las provincias de Cuenca y Valencia, al NW de Villargordo del Cabriel, describiéndose su estratigrafía, petrología y tectónica. Se datan estos materiales como del Plioceno inferior rectificándos las edades que se les había atribuído anteriormente y se presenta una abundante lista de especies fósiles clasificadas. El estudio se completa con un breve análisis de los materiales subyacentes y cubrientes y de sus relaciones con la facies citada

Non-volatile molecular memory elements based on ambipolar nanotube field effect transistors

We have fabricated air-stable n-type, ambipolar carbon nanotube field effect transistors (CNFETs), and used them in nanoscale memory cells. N-type transistors are achieved by annealing of nanotubes in hydrogen gas and contacting them by cobalt electrodes. Scanning gate microscopy reveals that the bulk response of these devices is similar to gold-contacted p-CNFETs, confirming that Schottky barrier formation at the contact interface determines accessibility of electron and hole transport regimes. The transfer characteristics and Coulomb Blockade (CB) spectroscopy in ambipolar devices show strongly enhanced gate coupling, most likely due to reduction of defect density at the silicon/silicon-dioxide interface during hydrogen anneal. The CB data in the ``on''-state indicates that these CNFETs are nearly ballistic conductors at high electrostatic doping. Due to their nanoscale capacitance, CNFETs are extremely sensitive to presence of individual charge around the channel. We demonstrate that this property can be harnessed to construct data storage elements that operate at the few-electron level.Comment: 6 pages text, 3 figures and 1 table of content graphic; available as NanoLetters ASAP article on the we