Analysis, Prevalence & Impact of Microplastics in Freshwater and Estuarine Environments Evidence Review 2 What are the sources of the microplastics found in freshwater environments?

This Rapid Evidence Assessment used the systematic review procedure to assess the current evidence available on the sources of the microplastics found in freshwater and estuarine environments. To fully comprehend the prevalence of microplastics in freshwater and estuarine environments, it is important to understand which sources contribute to the microplastics present and the relative importance of those sources. Furthermore, we need to understand the influence of any physical and biologically-mediated processes that affect the concentrations, characteristics and profile of the microplastic particles present, so that their influence can be taken into account when interpreting the microplastics present in terms of contributing sources. A review was conducted of literature, including grey literature, which reported evidence of the sources of the microplastics found in freshwater and estuarine environments. The factors influencing the transport and modification of microplastics in freshwater and estuarine environments were also considered, noting in particular those that alter the profile of microplastics thus obscuring identification of sources. Publications released prior to April 2019 were included in this review. Evidence was acquired according to a predefined set of questions, compiled into a database containing full details of the source and its relevance to the project questions, and the evidence analysed, taking into account reporting biases in the literature, to produce a digestible summary of the evidence base available to answer the main project question and sub-questions, namely, What are the sources of microplastics reported to have been found in freshwater and estuarine environments? a) Are these primary (i.e. manufactured) or secondary (i.e. degradation products) microplastics? b) Within studies reporting the predominant types of microplastics found, is there a link identified to local land use or industry? c) How are microplastics transported and modified in the freshwater and estuarine environments? d) Are microplastics from different sources prevalent in different matrices of the aquatic environment (biota, water, or sediment)

On p_T-broadening of high energy partons associated with the LPM effect in a finite-volume QCD medium

We study the contributions from radiation to $p_{\perp}$-broadening of a high energy parton traversing a QCD medium with a finite length $L$. The interaction between the parton and the medium is described by decorrelated static multiple scattering. Amplitudes of medium-induced gluon emission and parton self-energy diagrams are evaluated in the soft gluon limit in the BDMPS formalism. We find both the double-logarithmic correction from incoherent scattering, which is parametrically the same as that in single scattering, and the logarithmic correction from the LPM effect. Therefore, we expect a parametrically large correction from radiation to the medium-induced $p_\perp$-broadening in perturbative QCD.Comment: 19 pages, focusing only on calculations about the medium-induced diagrams, origin for double-log reinterpreted, final version to appear in JHE

Constant-angle surfaces in liquid crystals

We discuss some properties of surfaces in R3 whose unit normal has constant angle with an assigned direction field. The constant angle condition can be rewritten as an Hamilton-Jacobi equation correlating the surface and the direction field. We focus on examples motivated by the physics of interfaces in liquid crystals and of layered fluids, and discuss the properties of the constant-angle surfaces when the direction field is singular along a line (disclination) or at a point (hedgehog defect

Absolutely continuous invariant measures for random non-uniformly expanding maps

We prove existence of (at most denumerable many) absolutely continuous invariant probability measures for random one-dimensional dynamical systems with asymptotic expansion. If the rate of expansion (Lyapunov exponents) is bounded away from zero, we obtain finitely many ergodic absolutely continuous invariant probability measures, describing the asymptotics of almost every point. We also prove a similar result for higher-dimensional random non-uniformly expanding dynamical systems. The results are consequences of the construction of such measures for skew-products with essentially arbitrary base dynamics and asymptotic expansion along the fibers. In both cases our method deals with either critical or singular points for the random maps.Comment: 30 pages; 2 figures. Keywords: non-uniform expansion, random dynamics, slow recurrence, singular and critical set, absolutely continuous invariant measures, skew-product. To appear in Math Z, 201

Physics Opportunities of e+e- Linear Colliders

We describe the anticipated experimental program of an e+e- linear collider in the energy range 500 GeV -- 1.5 TeV. We begin with a description of current collider designs and the expected experimental environment. We then discuss precision studies of the W boson and top quark. Finally, we review the range of models proposed to explain the physics of electroweak symmetry breaking and show, for each case, the central role that the linear collider experiments will play in elucidating this physics. (to appear in Annual Reviews of Nuclear and Particle Science)Comment: 93 pages, latex + 23 figures; typos corrections + 1 reference adde

The Genomic Signature of Crop-Wild Introgression in Maize

The evolutionary significance of hybridization and subsequent introgression has long been appreciated, but evaluation of the genome-wide effects of these phenomena has only recently become possible. Crop-wild study systems represent ideal opportunities to examine evolution through hybridization. For example, maize and the conspecific wild teosinte Zea mays ssp. mexicana, (hereafter, mexicana) are known to hybridize in the fields of highland Mexico. Despite widespread evidence of gene flow, maize and mexicana maintain distinct morphologies and have done so in sympatry for thousands of years. Neither the genomic extent nor the evolutionary importance of introgression between these taxa is understood. In this study we assessed patterns of genome-wide introgression based on 39,029 single nucleotide polymorphisms genotyped in 189 individuals from nine sympatric maize-mexicana populations and reference allopatric populations. While portions of the maize and mexicana genomes were particularly resistant to introgression (notably near known cross-incompatibility and domestication loci), we detected widespread evidence for introgression in both directions of gene flow. Through further characterization of these regions and preliminary growth chamber experiments, we found evidence suggestive of the incorporation of adaptive mexicana alleles into maize during its expansion to the highlands of central Mexico. In contrast, very little evidence was found for adaptive introgression from maize to mexicana. The methods we have applied here can be replicated widely, and such analyses have the potential to greatly informing our understanding of evolution through introgressive hybridization. Crop species, due to their exceptional genomic resources and frequent histories of spread into sympatry with relatives, should be particularly influential in these studies

A surface-patterned chip as a strong source of ultracold atoms for quantum technologies

Laser-cooled atoms are central to modern precision measurements. They are also increasingly important as an enabling technology for experimental cavity quantum electrodynamics, quantum information processing and matter–wave interferometry. Although significant progress has been made in miniaturizing atomic metrological devices, these are limited in accuracy by their use of hot atomic ensembles and buffer gases. Advances have also been made in producing portable apparatus that benefits from the advantages of atoms in the microkelvin regime. However, simplifying atomic cooling and loading using microfabrication technology has proved difficult. In this Letter we address this problem, realizing an atom chip that enables the integration of laser cooling and trapping into a compact apparatus. Our source delivers ten thousand times more atoms than previous magneto-optical traps with microfabricated optics and, for the first time, can reach sub-Doppler temperatures. Moreover, the same chip design offers a simple way to form stable optical lattices. These features, combined with simplicity of fabrication and ease of operation, make these new traps a key advance in the development of cold-atom technology for high-accuracy, portable measurement devices

Complete experimental toolbox for alignment-free quantum communication

Quantum communication employs the counter-intuitive features of quantum physics to perform tasks that are im- possible in the classical world. It is crucial for testing the foundations of quantum theory and promises to rev- olutionize our information and communication technolo- gies. However, for two or more parties to execute even the simplest quantum transmission, they must establish, and maintain, a shared reference frame. This introduces a considerable overhead in communication resources, par- ticularly if the parties are in motion or rotating relative to each other. We experimentally demonstrate how to circumvent this problem with the efficient transmission of quantum information encoded in rotationally invariant states of single photons. By developing a complete toolbox for the efficient encoding and decoding of quantum infor- mation in such photonic qubits, we demonstrate the fea- sibility of alignment-free quantum key-distribution, and perform a proof-of-principle alignment-free entanglement distribution and violation of a Bell inequality. Our scheme should find applications in fundamental tests of quantum mechanics and satellite-based quantum communication.Comment: Main manuscript: 7 pages, 3 figures; Supplementary Information: 7 pages, 3 figure

Exoplanets and SETI

The discovery of exoplanets has both focused and expanded the search for extraterrestrial intelligence. The consideration of Earth as an exoplanet, the knowledge of the orbital parameters of individual exoplanets, and our new understanding of the prevalence of exoplanets throughout the galaxy have all altered the search strategies of communication SETI efforts, by inspiring new "Schelling points" (i.e. optimal search strategies for beacons). Future efforts to characterize individual planets photometrically and spectroscopically, with imaging and via transit, will also allow for searches for a variety of technosignatures on their surfaces, in their atmospheres, and in orbit around them. In the near-term, searches for new planetary systems might even turn up free-floating megastructures.Comment: 9 page invited review. v2 adds some references and v3 has other minor additions and modification

Invasion speeds for structured populations in fluctuating environments

We live in a time where climate models predict future increases in environmental variability and biological invasions are becoming increasingly frequent. A key to developing effective responses to biological invasions in increasingly variable environments will be estimates of their rates of spatial spread and the associated uncertainty of these estimates. Using stochastic, stage-structured, integro-difference equation models, we show analytically that invasion speeds are asymptotically normally distributed with a variance that decreases in time. We apply our methods to a simple juvenile-adult model with stochastic variation in reproduction and an illustrative example with published data for the perennial herb, \emph{Calathea ovandensis}. These examples buttressed by additional analysis reveal that increased variability in vital rates simultaneously slow down invasions yet generate greater uncertainty about rates of spatial spread. Moreover, while temporal autocorrelations in vital rates inflate variability in invasion speeds, the effect of these autocorrelations on the average invasion speed can be positive or negative depending on life history traits and how well vital rates ``remember'' the past