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Subglacial lakes beneath Antarctica’s fast-moving ice streams are known to undergo ∼1 km3 volume changes on annual timescales. Focusing on the MacAyeal Ice Stream (MacIS) lake system, we create a simple model for the response of subglacial water distribution to lake discharge events through assimilation of lake volume changes estimated from Ice, Cloud and land Elevation Satellite (ICESat) laser altimetry. We construct a steady-state water transport model in which known subglacial lakes are treated as either sinks or sources depending on the ICESat-derived filling or draining rates. The modeled volume change rates of five large subglacial lakes in the downstream portion of MacIS are shown to be consistent with observed filling rates if the dynamics of all upstream lakes are considered. However, the variable filling rate of the northernmost lake suggests the presence of an undetected lake of similar size upstream. Overall, we show that, for this fast-flowing ice stream, most subglacial lakes receive >90% of their water from distant distributed sources throughout the catchment, and we confirm that water is transported from regions of net basal melt to regions of net basal freezing. Our study provides a geophysically based means of validating subglacial water models in Antarctica and is a potential way to parameterize subglacial lake discharge events in large-scale ice-sheet models where adequate data are available.
As part of an ongoing program to better understand the early stages of massive star cluster evolution and the physical conditions required for their formation, we have obtained 10 μm (N-band) images with Gemini North of the nuclear region of the starburst galaxy He 2-10. Five massive star clusters still enshrouded in their natal cocoons with no optical counterparts were previously discovered by Kobulnicky & Johnson (1999) as optically thick thermal radio sources. Three of these five radio sources have strong 10 μm detections in only 10 minutes of integration time with Gemini. The blackbody temperatures of the dust cocoons are estimated to range from ∼ 40 — 150 K at their outer and inner edges, and the mass of these dust shells is ∼ 107 M⊙. The ages of the embedded stellar clusters must be < 106 years. The bolometric luminosities of the exciting clusters can be constrained to ∼ 108–9 L⊙, and the implied masses are > 106 M⊙. These three embedded clusters are responsible for at least 60% of the IRAS flux of the entire galaxy He 2-10.
N-band (10.8 μm) imaging of the blue compact starburst galaxy He 2-10 reveals the presence of four emission regions, which have no optical or near-IR counterparts. These sources correspond to the ‘ultradense H ii’ regions recently identified in 2cm and 6cm radio maps of this galaxy. We have used the N-band data to place constraints on the properties of the stellar clusters, that are deeply embedded within these dust-emitting regions.
Accurate reconstruction of the biomass, structure, and productivity of ancient forests from their fossilized remnants remains an interesting challenge in paleoecology. In well-preserved Tertiary fossil Metasequoia forests of Canada's Arctic, in situ stumps and fragments of stems, treetops, and branches contain substantial information about tree dimensions that can be used to determine tree height, stand biomass, and other characteristics such as canopy depth and structure, and the history of stand development. To validate a method for reconstructing the biomass of the Eocene floodplain Metasequoia forests of Axel Heiberg Island, we measured stump diameters and spacing, and stem, branch, and treetop characteristics in living Metasequoia glyptostroboides and Chamaecyparis thyoides stands in ways that simulate the limited measurements that can be made in well-preserved fossil forests in Canada and probably elsewhere. We used those limited measurements to estimate tree height and volume, branch and foliar dry weights, and tree biomass. The estimates derived from the limited data set are usually within 15% of the estimates derived from the methods currently used in forest ecology for determining those metrics in modern forests. Under appropriate conditions, the biomass of ancient forests can be estimated with reasonable confidence.
New trait technology incorporating 2,4-D resistance in soybean is dependent upon the ability of the plant to metabolize 2,4-D by the aryloxyalkanoate dioxygenase-12 protein (AAD-12). Our objectives were to determine AAD-12 expression during the daytime, throughout the leaf canopy, and before and after 2,4-D treatment for the events DAS-68416-4 and DAS-21606-3. Field experiments were conducted near Wanatah, IN in 2009 and Fowler, IN in 2009, 2010, and 2011. During the daytime, total AAD-12 expression was lowest between 12:30 and 15:30, averaging 161 ng cm−2, as compared to an average of 245 ng cm−2 in the morning and 243 ng cm−2 in the evening. The youngest fully emerged trifoliate in the DAS-68416-4 event had the highest AAD-12 expression, with means ranging from 369 to 390 ng cm−2, while the older leaves maintained a lower level of expression, 171 to 211 ng cm−2. The youngest leaves of event DAS-21606-3 had the highest level of AAD-12 expression (205 to 225 ng cm−2), while the level of AAD-12 was lower in older leaves (71 to 149 ng cm−2). In general, 2,4-D treatments did not reduce AAD-12 expression at 3, 7, 14, and 21 days after treatment; however, in a few instances AAD-12 expression was increased or decreased by 8 to 11% after 2,4-D treatment. Expression of AAD-12 was between 152 to 390 ng cm−2 for DAS-68416-4 and from 71 to 244 ng cm−2 for DAS-21606-3.
Long-acting injectable formulations of antipsychotics are treatment alternatives to oral agents.
To assess the efficacy of aripiprazole once-monthly compared with oral aripiprazole for maintenance treatment of schizophrenia.
A 38-week, double-blind, active-controlled, non-inferiority study; randomisation (2:2:1) to aripiprazole once-monthly 400 mg, oral aripiprazole (10–30 mg/day) or aripiprazole once-monthly 50mg (a dose below the therapeutic threshold for assay sensitivity). (Trial registration: clinicaltrials.gov, NCT00706654.)
A total of 1118 patients were screened, and 662 responders to oral aripiprazole were randomised. Kaplan–Meier estimated impending relapse rates at week 26 were 7.12% for aripiprazole once-monthly 400mg and 7.76% for oral aripiprazole. This difference (−0.64%, 95% CI −5.26 to 3.99) excluded the predefined non-inferiority margin of 11.5%. Treatments were superior to aripiprazole once-monthly 50mg (21.80%, P⩽0.001).
Aripiprazole once-monthly 400mg was non-inferior to oral aripiprazole, and the reduction in Kaplan–Meier estimated impending relapse rate at week 26 was statistically significant v. aripiprazole once-monthly 50 mg.
Greenhouse experiments were conducted in 2011 to evaluate the effect of mowing frequency and mowing height on four summer annual weed species (large crabgrass, barnyardgrass, giant ragweed, and common lambsquarters). Plants were clipped at three heights (5, 10, or 20 cm) and at two frequencies (single clipping or repeated clippings at the same height) to simulate mowing. A nonclipped control was also grown for each species. When clipped once, large crabgrass, barnyardgrass, and giant ragweed produced at least 90% of the total dry weight (DW) of the nonclipped plants, and common lambsquarters produced at least 75%. A single cut was generally not sufficient to prevent weed seed production or kill any of the weeds in this study. Repeated clipping reduced large crabgrass, giant ragweed, and common lambsquarters reproductive DW to 46, 27, and 10% respectively, of the nonclipped control. Barnyardgrass plants that were repeatedly clipped produced between 0 and 8% of the seed DW of nonclipped plants, depending on clipping height. Repeated clipping reduced weed total DW to below 40% for all species compared to nonclipped plants. Our results suggest that, unless combined with other weed management practices, repeated mowing may be necessary to limit the growth and seed production of these weed species.
We present Doppler tomographic observations of the transiting planet Kepler-13b (aka KOI-13b), a highly inflated hot Jupiter orbiting the Teff=8500 K primary of a hierarchical triple stellar system. As the planet transits the rapidly rotating host star, it successively blocks regions of the stellar disk with different radial velocities, causing a “bump” in the stellar spectral line shape, which we resolve spectroscopically. The manner in which this perturbation moves across the stellar line during the transit gives information on the relative alignment between the stellar spin and planetary orbital angular momentum vectors. This is a powerful statistical probe of planetary migration processes, as the expected spin-orbit misalignment distributions from dynamically cold migration (disk interactions) and dynamically hot migration (planet-planet scattering, Kozai cycles) are significantly different: the former will lead to primarily aligned orbits; the latter to a wide distribution. Doppler tomography also promises to be a powerful technique for confirming transiting planet candidates around rapidly rotating stars like Kepler-13A, which are not amenable to radial velocity follow-up and thus are currently a poorly sampled region of parameter space.
To determine the fraction of unnecessary antimicrobial use among patients with current and/or recent Clostridium difficile infection (CDI).
Retrospective review from January 2004 through December 2006.
Minneapolis Veterans Affairs Medical Center (MVAMC).
Patients with new-onset CDI diagnosed at the MVAMC without another CDI diagnosis in the prior 30 days.
Pharmacy and medical records were reviewed to identify incident CDI cases, non-CDI antimicrobial use during and up to 30 days after completion of CDI treatment, and patient characteristics. Two infectious disease physicians independently assessed non-CDI antimicrobial use, which was classified as unnecessary if not fully indicated. Factors associated with only unnecessary use were identified through univariable and multivariable analysis.
Of 246 patients with new-onset CDI, 141 (57%) received non-CDI antimicrobials during and/or after their CDI treatment, totaling 2,147 antimicrobial days and 445 antimicrobial courses. The two reviewers agreed regarding the necessity of antimicrobials in more than 99% of antimicrobial courses (85% initially, 14% after discussion). Seventy-seven percent of patients received at least 1 unnecessary antimicrobial dose, 26% of patients received only unnecessary antimicrobials, and 45% of total non-CDI antimicrobial days included unnecessary antimicrobials. The leading indications for unnecessary antimicrobial use were putative urinary tract infection and pneumonia. Drug classes frequently used unnecessarily were fluoroquinolones and β-lactams.
Twenty-six percent of patients with recent CDI received only unnecessary (and therefore potentially avoidable) antimicrobials. Heightened awareness and caution are needed when antimicrobial therapy is contemplated for patients with recent CDI.