2,123 research outputs found
Field Evaluations of Broadcast and Individual Mound Treatment for Red Imported Fire Ant, Solenopsis invicta Buren, (Hymenoptera; Formicidae) Control in Virginia, USA
Field evaluations were conducted to determine efficacy, residual activity, and knockdown potential for fire ant control products. Broadcast granular products (Advion, 0.045% indoxacarb; and Top Choice Insecticide, 0.0143% fipronil) were individually evaluated, and compared with a combination of two products applied together, and with individual mound applications of Maxforce Fire Ant Killer Bait (1.0% hydramethylnon). After application, the greatest percent reduction (90 days) were observed in the Advion/Top Choice combination plots (100.0%), followed by Top Choice alone (96.4%). Advion and MaxForce produced significantly lower foraging reductions at 90 days (61.2% and 27.5% respectively). At the conclusion of the test (day 360), significantly fewer ants were collected in the Advion (777.7), Top Choice (972.8), and combination plots (596.2) than in the control plots (1257.8) (df 13, F = 8.3, P < 0.05). The mean number of ants collected from MaxForce treatment plots was not significantly different from controls (P > 0.05). Overall, the efficacy and residual studies suggested that the Advion/Top Choice combination produced both the most rapid reduction in ant foraging and the longest lasting control (90%) at 300 days. When evaluating time to knockdown of foraging populations, the Advion/Top Choice combination also provided the most complete and rapid results by day 7, reducing foraging by 100%. While other products also performed well (75.6 - 95.9% reductions), both the MaxForce and Advion plots had significant increases in foraging at 30-90 days. Overall, foraging knockdown was the most complete in the Avion/Top Choice combination plots at 90 days
SIMULATION OF THE SNARE-MEMBRANE COLLISION IN MODAL FORM USING THE SCALAR AUXILIARY VARIABLE (SAV) METHOD
Collisions play an essential role in the sound production of many musical instruments, such as in the snare drum. Here, collisions occur between the stick and the batter head and between the snares and the bottom head. The latter involve interactions between fully distributed objects and are the subject of this work. From a simulation standpoint, simple explicit or semi-implicit schemes are prone to unstable numerical behaviour and an appropriate energy-conserving framework is required for stable simulation designs. Usually, this is accomplished via fully-implicit designs that are known to conserve energy but that require iterative solvers such as Newton-Raphson. Other than representing a computational bottleneck, iterative schemes present a variable operational cost per timestep and, furthermore, are serial in nature. This work will explore the possibility of simulating the snare-membrane collision using explicit designs obtained via a quadratisation of the nonlinear potential energy. A modal function basis will be employed for the spatial discretisation, allowing for fine-tuning damping ratios and natural frequencies
Efficient simulation of acoustic physical models with nonlinear dissipation
One long-term goal of physics-based sound synthesis and audio effect modeling has been to open the door to models without a counterpart in the real world. Less explored has been the fine-grained adjustment of the constituent physical laws that underpin such models. In this paper, the introduction of a nonlinear damping law into a plate reverberation model is explored, through the use of four different functions, transferred from the setting of virtual-analog electronics. First, a case study of an oscillator with nonlinear damping is investigated. Results are compared against linear dissipation, illustrating differing spectral characteristics. To solve the systems, a recently proposed numerical solver is employed, that entirely avoids the use of iterative routines such as Newton-Raphson for solving nonlinearities, thus allowing very efficient numerical solution. This scheme is then used to simulate a plate reverbation unit, and tests are run, to investigate spectral variations induced by nonlinear damping. Finally, a musical case is presented that includes frequency-dependent damping coefficients
Intermediate Mass Black Hole Induced Quenching of Mass Segregation in Star Clusters
In many theoretical scenarios it is expected that intermediate-mass black
holes (IMBHs, with masses M ~ 100-10000 solar masses) reside at the centers of
some globular clusters. However, observational evidence for their existence is
limited. Several previous numerical investigations have focused on the impact
of an IMBH on the cluster dynamics or brightness profile. Here we instead
present results from a large set of direct N-body simulations including single
and binary stars. These show that there is a potentially more detectable IMBH
signature, namely on the variation of the average stellar mass between the
center and the half-light radius. We find that the existence of an IMBH
quenches mass segregation and causes the average mass to exhibit only modest
radial variation in collisionally relaxed star clusters. This differs from when
there is no IMBH. To measure this observationally requires high resolution
imaging at the level of that already available from the Hubble Space Telescope
(HST) for the cores of a large sample of galactic globular clusters. With a
modest additional investment of HST time to acquire fields around the
half-light radius, it will be possible to identify the best candidate clusters
to harbor an IMBH. This test can be applied only to globulars with a half-light
relaxation time less than or equal to 1 Gyr, which is required to guarantee
efficient energy equipartition due to two-body relaxation.Comment: 15 pages, 3 figures, ApJ, in pres
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“I always wanted to see the night sky”: blind user preferences for Sensory Substitution Devices
Sensory Substitution Devices (SSDs) convert visual information into another sensory channel (e.g. sound) to improve the everyday functioning of blind and visually impaired persons (BVIP). However, the range of possible functions and options for translating vision into sound is largely open-ended. To provide constraints on the design of this technology, we interviewed ten BVIPs who were briefly trained in the use of three novel devices that, collectively, showcase a large range of design permutations. The SSDs include the ‘Depth-vOICe,’ ‘Synaestheatre’ and ‘Creole’ that offer high spatial, temporal, and colour resolutions respectively via a variety of sound outputs (electronic tones, instruments, vocals). The participants identified a range of practical concerns in relation to the devices (e.g. curb detection, recognition, mental effort) but also highlighted experiential aspects. This included both curiosity about the visual world (e.g. understanding shades of colour, the shape of cars, seeing the night sky) and the desire for the substituting sound to be responsive to movement of the device and aesthetically engaging
The Evolving Long-Term Outcome of Heart Transplantation in Amyloid Patients
Background: Both amyloid light chain (AL) amyloidosis and transthyretin-related (TTR) amyloid are expanding indications for heart transplantation (HTx). In the past, AL amyloid, in particular, had been a contraindication to HTx given its systemic nature and the increased risk for mortality. Modern treatments including proteasome inhibitors have allowed amyloid patients to receive heart transplants at an increasing rate. We sought to assess long-term post-transplant outcome in amyloid patients in the current era.
Methods: Between 2010 and 2015, we assessed 27 patients (5 AL, 10 TTR-wildtype (wt), 12 TTR-mutant (m)) underwent heart transplant for cardiac amyloidosis at our single center. A non-amyloid restrictive cardiomyopathy control population was included (n=18). Endpoints included 3-year outcomes including survival, freedom from CAV (as #212121 \u3edefined by stenosis ≥ 30% by angiography), freedom from non-fatal major adverse cardiac events (NF-MACE: myocardial infarction, new congestive heart failure, percutaneous coronary intervention, implantable cardioverter defibrillator/pacemaker implant, stroke), and freedom from any-treated rejection, acute cellular rejection, and antibody-mediated rejection.
Results: There was no significant difference between the AL amyloid, TTR-wt, TTR-m, and restrictive non-amyloid patients with respect to 3-year survival and 3-year freedom from CAV, NF-MACE, and rejection (see table). Endomyocardial biopsies post-transplant did not show amyloid. (see Table)
Conclusion: In the current era, both AL and TTR amyloid patients have acceptable mid-term outcome after heart transplantation. Larger numbers and longer follow up are needed to confirm these findings
981-52 Six-minute Walk Compared to Peak and Low-level Aerobic Capacity in 302 Patients with Heart Failure
Distances walked spontaneously during 6 min may reflect peak exerc capacity, the ability to sustain 6 min of low exercise without anaerobic metabolism, and non-metabolic factors such as stride. To determine how well 6-min walks in 302 heart failure patients reflected aerobic capacity at peak exercise (pkVO2) and/or R (VCO2/VO2) after 6min of low-level exercise similar to walking, 6-min walks were measured within 48 hrs of bicycle exercise with gas exchange during 6min 20-watt riding and then during incremental exercise.Although 6 min walk correlated with extremes of pkVO2, it varied widely (r=0.25) when pkVO2 was 10–20ml/kg/min (generally Class II-III). Although 6 min 20W ride required VO2 9 ±2ml/kg/min, similar to 3 METS estimated for walking, 6-min 20W R did not correlate well inversely with 6 min walk distance except at very short and long walks.In moderate heart failure, 6 min walk reflects factors other than aerobic capacity at peak or during 6 min of sustained low-level exercise
Mass Segregation in NGC 2298: limits on the presence of an Intermediate Mass Black Hole
[abridged] Theoretical investigations have suggested the presence of
Intermediate Mass Black Holes (IMBHs, with masses in the 100-10000 Msun range)
in the cores of some Globular Clusters (GCs). In this paper we present the
first application of a new technique to determine the presence or absence of a
central IMBH in globular clusters that have reached energy equipartition via
two-body relaxation. The method is based on the measurement of the radial
profile for the average mass of stars in the system, using the fact that a
quenching of mass segregation is expected when an IMBH is present. Here we
measure the radial profile of mass segregation using main-sequence stars for
the globular cluster NGC 2298 from resolved source photometry based on HST-ACS
data. The observations are compared to expectations from direct N-body
simulations of the dynamics of star clusters with and without an IMBH. The mass
segregation profile for NGC 2298 is quantitatively matched to that inferred
from simulations without a central massive object over all the radial range
probed by the observations, that is from the center to about two half-mass
radii. Profiles from simulations containing an IMBH more massive than ~ 300-500
Msun (depending on the assumed total mass of NGC 2298) are instead inconsistent
with the data at about 3 sigma confidence, irrespective of the IMF and binary
fraction chosen for these runs. While providing a null result in the quest of
detecting a central black hole in globular clusters, the data-model comparison
carried out here demonstrates the feasibility of the method which can also be
applied to other globular clusters with resolved photometry in their cores.Comment: 21 pages, 3 figures, ApJ accepte
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