380 research outputs found

    Forecasting dispersal of nonindigenous species

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    A leading conceptual model of the invasion process suggests that nonindigenous species (NIS) must pass through a series of ‘filters’ when dispersing from colonized to non-colonized regions. These steps include the initial dispersal of propagules, survival of these propagules upon encountering the new physicochemical environment, and biological integration into the new community. Here, I forecast invasions for two aquatic NIS, the spiny waterflea Bythotrephes longimanus and zebra mussel Dreissena polymorpha based on the entire invasion sequence using gravity models to assess movement of propagules, data on lake morphometry and physicochemistry, and data on fish community composition. The gravity models included information on movement patterns of recreationalists and life-history characteristics of the NIS that may facilitate invasions. I also contrast the abilities of a hierarchical approach to a single ‘all-in-one’ model that considered all variables simultaneously in detecting actual invasions versus false alarms. Here, the ‘all-in-one’ model was better at predicting invasions if they had, in fact, occurred. Next, I compare predictions of Bythotrephes invasions for three types of gravity models: total-flow-, production- and doubly-constrained. These models differ in the type of information required to parameterize the model. The Production-constrained model was most likely to detect actual invasions relative to false alarms, and the total-flow-constrained model was least likely to predict false positives. I also compare backcast patterns of propagule pressure for two groups of related species: one group comprising the spiny waterflea and the fishhook waterflea Cercopagis pengoi; and the other, the zebra mussel and quagga mussel Dreissena rostriformis bugensis. Differences in species\u27 life-histories may interact with various transport mechanisms to produce highly dissimilar levels of propagule pressure to inland lakes. Species with the broadest distribution had the highest propagule pressure scores. Finally, I examine the attributes of an invasion network formed by lakes invaded by spiny waterfleas connected by recreational traffic. I was interested in whether specific lakes served as ‘hubs’, and whether the network of lakes exhibited a scale-free topology. Management implications for a scale-free invasion network include a potential decrease in the overall rate of NIS spread if propagule flow from ‘hubs’ is reduced

    An asthenic symptom-complex: its diagnosis and treatment and relationship to the supra renal gland

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    (11 That the Asthenic symptom- Complex herein described is a definite Clinical entity. • (2). That it is definitely related to Addison's Disease and is therefore definitely related to the Supra Renal Gland. • (3). That this Asthenic symptom Complex can be treated by a Specific Therapy. • (4). That an extract of Supra Renal Gland whole substance is active by the mouth. • (5) That the cortex of the Supra Renal Gland is essential to life. • (6) That the medulla is not essential to life. • (7) That in view of this fact it is better to revert to the older terminology and to refer to the Gland as the Supra Renal gland. • (8) That it will be from clinical rather than from experimental knowledge that the functions of the Supra Renal Gland will be more fully discovered • (9) That the active principle of any gland extract may be destroyed in the process of manufacture and there is no method of proving that this has happened other than the clinical method. • (10) Sargent's White Adrenal Line was not pathognomonic of the Asthenic Symptoms Complex. • (11) That pathological conditions of the Supra Renal Gland exist in a great number of clinical disease unsuspected, and that sufficient pathological significance is not attributed to the Supra Renal Gland

    Using the Extrusive Volcanic Features of Mt. Marsabit, Kenya to Identify Regional Tectonic Stress

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    Extrusive volcanic features like vents, craters, and cones can produce alignments and other linear structures that indicate the orientations of feeder dikes and regional tectonic stresses. These dikes form parallel to the maximum compressional stress (σ1) and perpendicular to minimum compressive stress (σ3), and/or exploit preexisting planes of weakness. Volcanic constructs fed by these magmatic intrusions are therefore indicators of tectonic stress directions and subsurface structural fabrics, which can be deduced through detailed mapping and assessment of the spacing, shapes, and linear arrays of these volcanic features. Mt Marsabit (2.32°N, 37.97°E) is a massive 6,300 km2 off-axis volcano located in Northern Kenya on the eastern shoulder of the Kenyan Rift, 170 km east from the center of the East African Rift System (EARS). Initial construction began in the Miocene, with the peak of volcanic activity occurring in the Pliocene. A multitude of maar craters, scoria cones, and tuff cones developed in the Quaternary, primarily along the northern and eastern slopes. These extrusive volcanic features were mapped in the late eighties but have not been revisited using modern technology. Here we present findings from our analyses of the morphologies and alignments of 242 of extrusive volcanic features found on Marsabit. We then interpret the subsurface feeder system to off-axis volcanism in this sector of the EARS. Methodologies modified from Paulsen and Wilson (2010) and Muirhead et al. (2015) are used to map volcanic craters and cones using Google Earth. The orientations, shapes, and positions of volcanic features observed over the 8,000 km2 region indicate the presence of NE-SW orientated feeder dikes, which trend oblique to the general N-S trends observed in nearby sectors of the EARS such as faults found immediately south of Lake Turkana and the Elgeyo escarpment of the Kenyan rift. The strong NE-SW orientation of volcanic lineaments on Marsabit suggests that either a local NW-SE extension direction or a NE-SW orientated crustal fabric controls the geometry of the underlying plumbing system to this off-axis volcano. From this data we have created a series of rose diagrams to indicate the possible angles and locations of subsurface dikes, illustrating the regional tectonic stress field in Marsabit. We then compare these rose diagrams to other features found in the EARS

    Myocardial dysfunction after out-of-hospital cardiac arrest: predictors and prognostic implications.

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    We aim to determine the incidence of early myocardial dysfunction after out-of-hospital cardiac arrest, risk factors associated with its development, and association with outcome. A retrospective chart review was performed among consecutive out-of-hospital cardiac arrest (OHCA) patients who underwent echocardiography within 24 h of return of spontaneous circulation at three urban teaching hospitals. Our primary outcome is early myocardial dysfunction, defined as a left ventricular ejection fraction \u3c 40% on initial echocardiogram. We also determine risk factors associated with myocardial dysfunction using multivariate analysis, and examine its association with survival and neurologic outcome. A total of 190 patients achieved ROSC and underwent echocardiography within 24 h. Of these, 83 (44%) patients had myocardial dysfunction. A total of 37 (45%) patients with myocardial dysfunction survived to discharge, 39% with intact neurologic status. History of congestive heart failure (OR 6.21; 95% CI 2.54-15.19), male gender (OR 2.27; 95% CI 1.08-4.78), witnessed arrest (OR 4.20; 95% CI 1.78-9.93), more than three doses of epinephrine (OR 6.10; 95% CI 1.12-33.14), more than four defibrillations (OR 4.7; 95% CI 1.35-16.43), longer duration of resuscitation (OR 1.06; 95% CI 1.01-1.10), and therapeutic hypothermia (OR 3.93; 95% CI 1.32-11.75) were associated with myocardial dysfunction. Cardiopulmonary resuscitation immediately initiated by healthcare personnel was associated with lower odds of myocardial dysfunction (OR 0.40; 95% CI 0.17-0.97). There was no association between early myocardial dysfunction and mortality or neurological outcome. Nearly half of OHCA patients have myocardial dysfunction. A number of clinical factors are associated with myocardial dysfunction, and may aid providers in anticipating which patients need early diagnostic evaluation and specific treatments. Early myocardial dysfunction is not associated with neurologically intact survival

    High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: part 2, photon noise theory

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    High-resolution broadband spectroscopy at near-infrared (NIR) wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar, with the TEDI interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec NIR echelle spectrograph. These are the first multidelay EDI demonstrations on starlight. We demonstrated very high (10×) resolution boost and dramatic (20× or more) robustness to point spread function wavelength drifts in the native spectrograph. Data analysis, results, and instrument noise are described in a companion paper (part 1). This part 2 describes theoretical photon limited and readout noise limited behaviors, using simulated spectra and instrument model with noise added at the detector. We show that a single interferometer delay can be used to reduce the high frequency noise at the original resolution (1× boost case), and that except for delays much smaller than the native response peak half width, the fringing and nonfringing noises act uncorrelated and add in quadrature. This is due to the frequency shifting of the noise due to the heterodyning effect. We find a sum rule for the noise variance for multiple delays. The multiple delay EDI using a Gaussian distribution of exposure times has noise-to-signal ratio for photon-limited noise similar to a classical spectrograph with reduced slitwidth and reduced flux, proportional to the square root of resolution boost achieved, but without the focal spot limitation and pixel spacing Nyquist limitations. At low boost (∼1×) EDI has ∼1.4× smaller noise than conventional, and at >10× boost, EDI has ∼1.4× larger noise than conventional. Readout noise is minimized by the use of three or four steps instead of 10 of TEDI. Net noise grows as step phases change from symmetrical arrangement with wavenumber across the band. For three (or four) steps, we calculate a multiplicative bandwidth of 1.8:1 (2.3:1), sufficient to handle the visible band (400 to 700 nm, 1.8:1) and most of TripleSpec (2.6:1)

    Estimating functions of canonical correlation coefficients

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    Let [rho]21,...,[rho]2p be the squares of the population canonical correlation coefficients from a normal distribution. This paper is concerned with the estimation of the parameters [delta]1,...,[delta]p, where [delta]i = [rho]2i/(1 - [rho]2i), i = 1,...,p, in a decision theoretic way. The approach taken is to estimate a parameter matrix [Delta] whose eigenvalues are [delta]1,...,[delta]p, given a random matrix F whose eigenvalues have the same distribution as r2i/(1 - r2i), i = 1,...,p, where r1,...,rp are the sample canonical correlation coefficients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25545/1/0000087.pd

    Failure of interpolation in the intuitionistic logic of constant domains

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    This paper shows that the interpolation theorem fails in the intuitionistic logic of constant domains. This result refutes two previously published claims that the interpolation property holds.Comment: 13 pages, 0 figures. Overlaps with arXiv 1202.1195 removed, the text thouroughly reworked in terms of notation and style, historical notes as well as some other minor details adde

    TEDI: the TripleSpec Exoplanet Discovery Instrument

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    The TEDI (TripleSpec - Exoplanet Discovery Instrument) will be the first instrument fielded specifically for finding low-mass stellar companions. The instrument is a near infra-red interferometric spectrometer used as a radial velocimeter. TEDI joins Externally Dispersed Interferometery (EDI) with an efficient, medium-resolution, near IR (0.9 - 2.4 micron) echelle spectrometer, TripleSpec, at the Palomar 200" telescope. We describe the instrument and its radial velocimetry demonstration program to observe cool stars.Comment: 6 Pages, To Appear in SPIE Volume 6693, Techniques and Instrumentation for Detection of Exoplanets II
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