Survival, Development and Population Dynamics of \u3ci\u3eEmpoasca Fabae\u3c/i\u3e (Homoptera: Cicadellidae) on Three Legume Hosts

Survival and development of potato leafhopper, Empoasca fabae, nymphs were measured on alfalfa (Medicago sativa), birdsfoot trefoil (Lotus corniculatus), and red clover (Trifolium pratense). Survival was not significantly different among host plants (mean = 62%). There was no interaction between sex and host plant for developmental time. Males developed significantly faster than females. Developmental time was fastest on alfalfa, intermediate on trefoil, and slowest on red clover. Plots of alfalfa, trefoil, and red clover were planted to compare the seasonal abundance of the potato leafhopper in the three forages. Nymphs were more abundant in trefoil than in alfalfa and red clover late in July, but no differences occurred on the other sample dates. At their peak, adults were more abundant in alfalfa than in trefoil and red clover

Mapping Antarctic crevasses and their evolution with deep learning applied to satellite radar imagery

The fracturing of glaciers and ice shelves in Antarctica influences their dynamics and stability. Hence, data on the evolving distribution of crevasses are required to better understand the evolution of the ice sheet, though such data have traditionally been difficult and time-consuming to generate. Here, we present an automated method of mapping crevasses on grounded and floating ice with the application of convolutional neural networks to Sentinel-1 synthetic aperture radar backscatter data. We apply this method across Antarctica to images acquired between 2015 and 2022, producing a 7.5-year record of composite fracture maps at monthly intervals and 50 m spatial resolution and showing the distribution of crevasses around the majority of the ice sheet margin. We develop a method of quantifying changes to the density of ice shelf fractures using a time series of crevasse maps and show increases in crevassing on Thwaites and Pine Island ice shelves over the observational period, with observed changes elsewhere in the Amundsen Sea dominated by the advection of existing crevasses. Using stress fields computed using the BISICLES ice sheet model, we show that much of this structural change has occurred in buttressing regions of these ice shelves, indicating a recent and ongoing link between fracturing and the developing dynamics of the Amundsen Sea sector.</p

Wide-Field Imaging from Space of Early-Type Galaxies and Their Globular Clusters

Wide-field imaging from space will reveal a wealth of information about the globular cluster systems of any galaxies in the local universe that are observed by such a mission. Individual globular clusters around galaxies in the local universe have compact sizes that are ideal for the excellent spatial resolution afforded by space-based imaging, while systems of these globular clusters have large spatial extent that can only be fully explored by wide-field imaging. One example of the science return from such a study is the determination of the major formation epoch(s) of galaxies from the ages of their globular clusters determined via their optical to near-infrared colors. A second example is determining the sites of metal-poor globular cluster formation from their cosmological bias, which constrains the formation of structures early in the universe.Comment: To appear in the conference proceedings of "Wide Field Imaging from Space" published in New Astronomy Reviews, eds. T. McKay, A. Fruchter, & E. Linde

Catalog Matching with Astrometric Correction and its Application to the Hubble Legacy Archive

Object cross-identification in multiple observations is often complicated by the uncertainties in their astrometric calibration. Due to the lack of standard reference objects, an image with a small field of view can have significantly larger errors in its absolute positioning than the relative precision of the detected sources within. We present a new general solution for the relative astrometry that quickly refines the World Coordinate System of overlapping fields. The efficiency is obtained through the use of infinitesimal 3-D rotations on the celestial sphere, which do not involve trigonometric functions. They also enable an analytic solution to an important step in making the astrometric corrections. In cases with many overlapping images, the correct identification of detections that match together across different images is difficult to determine. We describe a new greedy Bayesian approach for selecting the best object matches across a large number of overlapping images. The methods are developed and demonstrated on the Hubble Legacy Archive, one of the most challenging data sets today. We describe a novel catalog compiled from many Hubble Space Telescope observations, where the detections are combined into a searchable collection of matches that link the individual detections. The matches provide descriptions of astronomical objects involving multiple wavelengths and epochs. High relative positional accuracy of objects is achieved across the Hubble images, often sub-pixel precision in the order of just a few milli-arcseconds. The result is a reliable set of high-quality associations that are publicly available online.Comment: 9 pages, 9 figures, accepted for publication in the Astrophysical Journa

The dynamics of Southern Ocean storm tracks

The mechanisms that initiate and maintain oceanic "storm tracks" (regions of anomalously high eddy kinetic energy) are studied in a wind-driven, isopycnal, primitive equation model with idealized bottom topography. Storm tracks are found downstream of the topography in regions strongly influenced by a largescale stationary meander that is generated by the interaction between the background mean flow and the topography. In oceanic storm tracks the length scale of the stationary meander differs from that of the transient eddies, a point of distinction from the atmospheric storm tracks. When the zonal length and height of the topography are varied, the storm-track intensity is largely unchanged and the downstream storm-track length varies only weakly. The dynamics of the storm track in this idealized configuration are investigated using a wave activity flux (related to the Eliassen-Palmflux and eddy energy budgets). It is found that vertical fluxes of wave activity (which correspond to eddy growth by baroclinic conversion) are localized to the region influenced by the standing meander. Farther downstream, organized horizontal wave activity fluxes (which indicate eddy energy fluxes) are found. A mechanism for the development of oceanic storm tracks is proposed: the standing meander initiates localized conversion of energy from the mean field to the eddy field, while the storm track develops downstream of the initial baroclinic growth through the ageostrophic flux ofMontgomery potential. Finally, the implications of this analysis for the parameterization and prediction of storm tracks in ocean models are discussed

Evaluation of a cheap ultrasonic stage for light source coherence function measurement, optical coherence tomography and dynamic focusing

We evaluate the performance of a cheap ultrasonic stage in setups related to optical coherence tomography. The stage was used in several configurations: (1) optical delay line in an optical coherence tomography (OCT) setup; (2) as a delay line measuring coherence function of a low coherence source (e. g. superluminescent diode) and (3) in a dynamic focusing arrangement. The results are as follows: the stage is suitable for coherence function measurement (coherence length up to 70 mu m) of the light source and dynamic focusing. We found it unsuitable for OCT due to an unstable velocity profile. Despite this, the velocity profile has a repeatable shape (4% over 1000 A-scans) and slight modifications to the stage promise wider applications

ARE SSRIs RESPONSIBLE FOR PRECIPITATING SUICIDAL IDEATION IN TEENAGERS WITH ‘SUBSYNDROMAL’ BIPOLAR AFFECTIVE DISORDER WHO HAVE BEEN MISDIAGNOSED WITH UNIPOLAR DEPRESSION?

Concerns have recently been raised about a possible link between suicidal ideation and the use of SSRIs in teenagers diagnosed with unipolar depression, such that the USA FDA and UK CSM have issued warnings regarding the use of SSRIs in adolescents with depression. We investigated this phenomenon first by recognizing that the initial presentation of unipolar and bipolar depression may only differ in subtle ways and with the result being that a significant number of patients are misdiagnosed at the expense of patient outcomes. This is especially pertinent as patients with bipolar disorder have increased lifetime rates of suicide as compared with those patients with unipolar depression. The normal developmental trajectory of bipolar disorder often involves recurrent depressive episodes in early adolescence before the development of hypomanic/manic episodes. Therefore, a misdiagnosis of bipolar disorder as unipolar depression in teenagers could explain the failure of SSRIs to adequately treat depressive episodes. A suboptimal response to SSRIs and so a lack of control of the depression is a risk factor for suicide. One reason for this suboptimal response is the markedly different neurotransmission involved in bipolar depression as compared to the neurotransmitter systems operated on by SSRIs. In bipolar disorder, dopamine is the principal neurotransmitter disrupted and we marshal structural, pharmacological and biochemical evidence to support this claim. One important strand of evidence involves polymorphisms in D1 and D2 dopamine receptors being implicated in the pathogenesis of bipolar affective disorder. Serotonin neurotransmission is affected by SSRIs, however the role of serotonin in bipolar disorder is much more ambiguous. The conclusion we arrive at is that the link between suicidality and SSRI use in adolescents diagnosed with unipolar depression may in fact be due to inappropriate treatment of misdiagnosed bipolar disorder that has yet to manifest with hypomanic/manic symptoms

Australian Aboriginal mortality and coronary heart disease : a demographic inquiry

This thesis has attempted to evaluate whether Australian Aboriginal mortality patterns are different from those exhibited by indigenous groups in other countries or by the general Australian population; and whether the high rate of coronary heart disease among Australian Aborigines is attributable to the underlying prevalence of specific lifestyle (risk) factors. At a macro-level, I have compared contemporary mortality patterns of and risk factor prevalence levels among Australian Aborigines and other indigenous groups. At a micro-level, I have made the same comparisons between Aborigines living in western New South Wales (especially those in Bourke) and other Australians. This study has made four important points regarding these issues. The first point is that although Australian Aborigines and other indigenous groups have similar patterns of high adult mortality, the relative importance of some more notable causes of death is strikingly different. The second point is that Aborigines have much higher total and age-specific death rates than other Australians, especially during adulthood and most notably from circulatory system diseases. The third point is that, compared with the general Australian population, Bourke Aborigines have much higher risk factor prevalence levels for a number of coronary heart disease risk factors. The fourth and final point is that Bourke Aboriginal risk factor prevalence levels tend to vary quite considerably by several demographic, environmental, and social-cultural conditions (risk markers) — more specifically, by age, location, employment status, and pay period. Overall, these findings suggest that the mortality pattern of Australian Aborigines is experienced by no other population; and that lifestyle factors, which are influenced by often uncontrollable conditions, can at least partially account for the observed high rate of coronary heart disease

Towards a radiocarbon calibration for oxygen isotope stage 3 using New Zealand kauri (Agathis australis)

It is well known that radiocarbon years do not directly equate to calendar time. As a result, considerable effort has been devoted to generating a decadally resolved calibration curve for the Holocene and latter part of the last termination. A calibration curve that can be unambiguously attributed to changes in atmospheric ¹⁴C content has not, however, been generated beyond 26 kyr cal BP, despite the urgent need to rigorously test climatic, environmental, and archaeological models. Here, we discuss the potential of New Zealand kauri (Agathis australis) to define the structure of the ¹⁴C calibration curve using annually resolved tree rings and thereby provide an absolute measure of atmospheric ¹⁴C. We report bidecadally sampled ¹⁴C measurements obtained from a floating 1050-yr chronology, demonstrating repeatable ¹⁴C measurements near the present limits of the dating method. The results indicate that considerable scope exists for a high-resolution ¹⁴C calibration curve back through OIS-3 using subfossil wood from this source