311 research outputs found
Studies of physiological alterations in cereals induced by greenbug, Schizaphis graminum (Rondani) and Russian wheat aphid, Diuraphis noxia (Mordvilko)
Electrical conductivity of the Pampean Shallow Subduction Region of Argentina near 33 S: evidence for a slab window
We present a three-dimensional (3-D) interpretation of 117 long period (20â4096 s) magnetotelluric (MT) sites between 31°S and 35°S in western Argentina. They cover the most horizontal part of the Pampean shallow angle subduction of the Nazca Plate and extend south into the more steeply dipping region. Sixty-two 3-D inversions using various smoothing parameters and data misfit goals were done with a nonlinear conjugate gradient (NLCG) algorithm. A dominant feature of the mantle structure east of the horizontal slab is a conductive plume rising from near the top of the mantle transition zone at 410 km to the probable base of the lithosphere at 100 km depth. The subducted slab is known to descend to 190 km just west of the plume, but the Wadati-Benioff zone cannot be traced deeper. If the slab is extrapolated downdip it slices through the plume at 250 km depth. Removal of portions of the plume or blocking vertical current flow at 250 km depth significantly changes the predicted responses. This argues that the plume is not an artifact and that it is continuous. The simplest explanation is that there is a âwedgeâ-shaped slab window that has torn laterally and opens down to the east with its apex at the plume location. Stress within the slab and seismic tomography support this shape. Its northern edge likely explains why there is no deep seismicity south of 29°S.Fil: Burd, Aurora I.. University of Washington; Estados UnidosFil: Booker, John R.. University of Washington; Estados UnidosFil: Mackie, Randall. Land General Geophysics; ItaliaFil: Pomposiello, Maria Cristina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de GeocronologĂa y GeologĂa Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de GeocronologĂa y GeologĂa Isotopica; ArgentinaFil: Favetto, Alicia Beatriz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de GeocronologĂa y GeologĂa Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de GeocronologĂa y GeologĂa Isotopica; Argentin
What Search Data Shows About Americans and Guns During the COVID-19 Crisis
With millions of Americans staying at home across the country during a crisis of intense emotional and economic stress, gun safety advocates have raised concerns about increased risks of unintentional shootings, domestic violence shootings, gun suicides, and city gun violence. Unprecedented spikes in background checks, meanwhile, reflect a dramatic increase in gun purchasing that compounds these risks.Federal background check data, however, fails to capture the full spectrum of ways that people acquire guns, as well as the number of people who are removing guns from gun lockers or other storage. In an effort to cast additional light on issues of firearm access during this stage of the COVID-19 crisis, we used real-time Google search data to gauge interest in buying and cleaning guns across the country
Toward a better understanding of fishâbased contribution to ocean carbon flux
Fishes are the dominant vertebrates in the ocean, yet we know little of their contribution to carbon export flux at regional to global scales. We synthesize the existing information on fishâbased carbon flux in coastal and pelagic waters, identify gaps and challenges in measuring this flux and approaches to address them, and recommend research priorities. Based on our synthesis of passive (fecal pellet sinking) and active (migratory) flux of fishes, we estimated that fishes contribute an average (± standard deviation) of about 16.1% (±â13%) to total carbon flux out of the euphotic zone. Using the mean value of modelâgenerated global carbon flux estimates, this equates to an annual flux of 1.5â±â1.2 Pg C yrâ1. High variability in estimations of the fishâbased contribution to total carbon flux among previous field studies and reported here highlight significant methodological variations and observational gaps in our present knowledge. Communityâadopted methodological standards, improved and more frequent measurements of biomass and passive and active fluxes of fishes, and stronger linkages between observations and models will decrease uncertainty, increase our confidence in the estimation of fishâbased carbon flux, and enable identification of controlling factors to account for spatial and temporal variability. Better constraints on this key component of the biological pump will provide a baseline for understanding how ongoing climate change and harvest will affect the role fishes play in carbon flux
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Effects of dredge deposits on seagrasses : an integrative model for Laguna Madre : concluding report. Volume I, Executive Summary.
Interagency Coordination Team, U.S. Army Corps of Engineers, Galveston District, The University of Texas Marine Science Institute, Texas A&M University Department of Oceanography, Texas Parks and Wildlife DepartmentThis report presents the results of an interdisciplinary collaborative effort to develop an integrative model for
seagrass productivity in Laguna Madre. One of the major components of this integrative model is the Laguna
Madre Seagrass Model (LMSM) which was designed to interface with other component models described in this
report, including carbon and nitrogen allocation, sediment diagenesis, and spectral irradiance and radiative
transfer. Linkage with hydrodynamic and sediment transport models provided a potentially valuable
management tool to assess the effects of maintenance dredging and resuspension of dredged material deposits
on seagrasses of Laguna Madre.Texas A&M University and the U.S. Army Corps of Engineers (Galveston District) 96-PL-03Marine Scienc
Carbapenemase-producing organisms: a global scourge
The dramatic increase in the prevalence and clinical impact of infections caused by bacteria producing carbapenemases is a global health concern. Carbapenemase production is especially problematic when encountered in members of the family Enterobacteriaceae. Due to their ability to readily spread and colonize patients in healthcare environments, preventing the transmission of these organisms is a major public health initiative and coordinated international effort are needed. Central to the treatment and control of carbapenemase-producing organisms (CPOs) are phenotypic (growth-/biochemical-dependent) and nucleic acidâbased carbapenemase detection tests that identify carbapenemase activity directly or their associated molecular determinants. Importantly, bacterial isolates harboring carbapenemases are often resistant to multiple antibiotic classes, resulting in limited therapy options. Emerging agents, novel antibiotic combinations and treatment regimens offer promise for management of these infections. This review highlights our current understanding of CPOs with emphasis on their epidemiology, detection, treatment, and control
Towards Improved Quantum Simulations and Sensing with Trapped 2D Ion Crystals via Parametric Amplification
Improving coherence is a fundamental challenge in quantum simulation and
sensing experiments with trapped ions. Here we discuss, experimentally
demonstrate, and estimate the potential impacts of two different protocols that
enhance, through motional parametric excitation, the coherent spin-motion
coupling of ions obtained with a spin-dependent force. The experiments are
performed on 2D crystal arrays of approximately one hundred Be ions
confined in a Penning trap. By modulating the trapping potential at close to
twice the center-of-mass mode frequency, we squeeze the motional mode and
enhance the spin-motion coupling while maintaining spin coherence. With a
stroboscopic protocol, we measure dB of motional squeezing below
the ground-state motion, from which theory predicts a dB enhancement in
the sensitivity for measuring small displacements using a recently demonstrated
protocol [Science , 673 (2021)]. With a continuous squeezing
protocol, we measure and accurately calibrate the parametric coupling strength.
Theory suggests this protocol can be used to improve quantum spin squeezing,
limited in our system by off-resonant light scatter. We illustrate numerically
the trade-offs between strong parametric amplification and motional dephasing
in the form of center-of-mass frequency fluctuations for improving quantum spin
squeezing in our set-up.Comment: 11 pages, 6 figure
Collective traffic-like movement of ants on a trail: dynamical phases and phase transitions
The traffic-like collective movement of ants on a trail can be described by a
stochastic cellular automaton model. We have earlier investigated its unusual
flow-density relation by using various mean field approximations and computer
simulations. In this paper, we study the model following an alternative
approach based on the analogy with the zero range process, which is one of the
few known exactly solvable stochastic dynamical models. We show that our theory
can quantitatively account for the unusual non-monotonic dependence of the
average speed of the ants on their density for finite lattices with periodic
boundary conditions. Moreover, we argue that the model exhibits a continuous
phase transition at the critial density only in a limiting case. Furthermore,
we investigate the phase diagram of the model by replacing the periodic
boundary conditions by open boundary conditions.Comment: 8 pages, 6 figure
On the Stability of the Einstein Static Universe
We show using covariant techniques that the Einstein static universe
containing a perfect fluid is always neutrally stable against small
inhomogeneous vector and tensor perturbations and neutrally stable against
adiabatic scalar density inhomogeneities so long as c_{s}^2>1/5, and unstable
otherwise. We also show that the stability is not significantly changed by the
presence of a self-interacting scalar field source, but we find that spatially
homogeneous Bianchi type IX modes destabilise an Einstein static universe. The
implications of these results for the initial state of the universe and its
pre-inflationary evolution are also discussed.Comment: some additional comments and references; version to appear in Class.
Quant. Gra
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