A fundamental approach to the sticking of insect residues to aircraft wings

A proposed testing scheme is described for obtaining data on the effects of surface roughness and surface energy on insect adhesion. The road test apparatus is discussed as well as surface preparation techniques. Uncoated and polymer coated metal substrates were analyzed by SEM/ESCA/IRS before and following collision with insects. Critical surface tensions of unexposed Nyebar and poly sulfone coatings were 10 and 33 dynes/cm, respectively, as determined from contact angles. A total of 95% of insect residues collected belong to order Diptera. Significantly less insect debris was detected on the coated plates as compared to the uncoated plates. Minimal contamination at the 5 nm level of both coated and uncoated plates occurs even after hours of exposure to road conditions as determined by ESCA analysis. The presence of nitrogen detected by ESCA on exposed plates is unequivocal evidence for insect residues left on plates

Precision determination of absolute neutron flux

A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using a method of an alpha-gamma counter. The method involves only the counting of measured rates and is independent of neutron cross sections, decay chain branching ratios, and neutron beam energy. For the measurement, a target of 10B-enriched boron carbide totally absorbed the neutrons in a monochromatic beam, and the rate of absorbed neutrons was determined by counting 478keV gamma rays from neutron capture on 10B with calibrated high-purity germanium detectors. A second measurement based on Bragg diffraction from a perfect silicon crystal was performed to determine the mean de Broglie wavelength of the beam to a precision of 0.024 %. With these measurements, the detection efficiency of a neutron monitor based on neutron absorption on 6Li was determined to an overall uncertainty of 0.058 %. We discuss the principle of the alpha-gamma method and present details of how the measurement was performed including the systematic effects. We also describe how this method may be used for applications in neutron dosimetry and metrology, fundamental neutron physics, and neutron cross section measurements.Comment: 44 page

Comparative evaluation of the impact of WRF/NMM and WRF/ARW meteorology on CMAQ simulations for PM_2.5 and its related precursors during the 2006 TexAQS/GoMACCS study

This study presents a comparative evaluation of the impact of WRF-NMM and WRF-ARW meteorology on CMAQ simulations of PM_2.5, its composition and related precursors over the eastern United States with the intensive observations obtained by aircraft (NOAA WP-3), ship and surface monitoring networks (AIRNow, IMPROVE, CASTNet and STN) during the 2006 TexAQS/GoMACCS study. The results at the AIRNow surface sites show that both ARW-CMAQ and NMM-CMAQ reproduced day-to-day variations of observed PM_2.5 and captured the majority of observed PM_2.5 within a factor of 2 with a NMB value of −0.4% for ARW-CMAQ and −18% for NMM-CMAQ. Both models performed much better at the urban sites than at the rural sites, with greater underpredictions at the rural sites. Both models consistently underestimated the observed PM_2.5 at the rural IMPROVE sites by −1% for the ARW-CMAQ and −19% for the NMM-CMAQ. The greater underestimations of SO₄²⁻, OC and EC by the NMM-CMAQ contributed to increased underestimation of PM_2.5 at the IMPROVE sites. The NMB values for PM_2.5 at the STN urban sites are 15% and −16% for the ARW-CMAQ and NMM-CMAQ, respectively. The underestimation of PM_2.5 at the STN sites by the NMM-CMAQ mainly results from the underestimations of the SO₄²⁻, NH₄⁺ and TCM components, whereas the overestimation of PM_2.5 at the STN sites by the ARW-CMAQ results from the overestimations of SO₄²⁻, NO₃⁻, and NH₄⁺. The Comparison with WP-3 aircraft measurements reveals that both ARW-CMAQ and NMM-CMAQ have very similar model performance for vertical profiles for PM_2.5 chemical components (SO₄²⁻, NH₄⁺) and related gaseous species (HNO₃, SO₂, NH₃, isoprene, toluene, terpenes) as both models used the same chemical mechanisms and emissions. The results of ship along the coast of southeastern Texas over the Gulf of Mexico show that both models captured the temporal variations and broad synoptic change seen in the observed HCHO and acetaldehyde with the means NMB <30% most of the time but they consistently underestimated terpenes, isoprene, toluene and SO₂

Measurement of the Neutron Lifetime by Counting Trapped Protons in a Cold Neutron Beam

A measurement of the neutron lifetime $\tau_{n}$ performed by the absolute counting of in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto a silicon detector held at a high potential and counted with nearly unit efficiency. The neutrons were counted by a device with an efficiency inversely proportional to neutron velocity, which cancels the dwell time of the neutron beam in the trap. The result is $\tau_{n} = (886.6\pm1.2{\rm [stat]}\pm3.2{\rm [sys]})$ s, which is the most precise measurement of the lifetime using an in-beam method. The systematic uncertainty is dominated by neutron counting, in particular the mass of the deposit and the $^{6}$Li({\it{n,t}}) cross section. The measurement technique and apparatus, data analysis, and investigation of systematic uncertainties are discussed in detail.Comment: 71 pages, 20 figures, 9 tables; submitted to PR

Real-Time Coral Stress Observations Before, During, and After Beach Nourishment Dredging Offshore SE Florida

Beach nourishment in Southeast Florida involves dredging sand source borrow areas located between offshore reefs. From May 2005 to February 2006 Broward County, FL. nourished 10.9 km of beach with 1.5 ×106 m3 of sand. As part of a program to monitor potential reef community impacts, a visual stress index was developed from laboratory experiments and histological analyses for three stony coral species (Montastrea cavernosa, Solenastrea bournoni, and Siderastrea siderea). Scoring involved healthy = 0; moderately stressed = 1 (polyp swelling, increased mucus); markedly stressed = 2 (coloration changes, increased mucus secretion, tissue thinning); and severely stressed = 3 (severe swelling/thinning tissue erosion/necrosis). Colonies were scored weekly at sites adjacent to borrow areas and control sites pre-, during, and post-dredging. Permit conditions were established which would suspend dredging based on mean stress index values above 1.5 at 50% of monitored sites adjacent to borrow areas. This condition was never met. However, three hurricanes, passing the region during dredging, contributed to an elevated mean stress level above 1.0. Post-dredging observations documented recovery to pre-dredging stress levels. This program was effectively used to monitor stress on a sensitive marine habitat adjacent to sediment dredging activities

A Novel Genome-Wide Association Study Approach Using Genotyping by Exome Sequencing Leads to the Identification of a Primary Open Angle Glaucoma Associated Inversion Disrupting ADAMTS17

Closed breeding populations in the dog in conjunction with advances in gene mapping and sequencing techniques facilitate mapping of autosomal recessive diseases and identification of novel disease-causing variants, often using unorthodox experimental designs. In our investigation we demonstrate successful mapping of the locus for primary open angle glaucoma in the Petit Basset Griffon Vendéen dog breed with 12 cases and 12 controls, using a novel genotyping by exome sequencing approach. The resulting genome-wide association signal was followed up by genome sequencing of an individual case, leading to the identification of an inversion with a breakpoint disrupting the ADAMTS17 gene. Genotyping of additional controls and expression analysis provide strong evidence that the inversion is disease causing. Evidence of cryptic splicing resulting in novel exon transcription as a consequence of the inversion in ADAMTS17 is identified through RNAseq experiments. This investigation demonstrates how a novel genotyping by exome sequencing approach can be used to map an autosomal recessive disorder in the dog, with the use of genome sequencing to facilitate identification of a disease-associated variant

Comprehensive Cardiovascular magnetic resonance of myocardial mechanics in mice using three-dimensional cine DENSE

<p>Abstract</p> <p>Background</p> <p>Quantitative noninvasive imaging of myocardial mechanics in mice enables studies of the roles of individual genes in cardiac function. We sought to develop comprehensive three-dimensional methods for imaging myocardial mechanics in mice.</p> <p>Methods</p> <p>A 3D cine DENSE pulse sequence was implemented on a 7T small-bore scanner. The sequence used three-point phase cycling for artifact suppression and a stack-of-spirals <it>k</it>-space trajectory for efficient data acquisition. A semi-automatic 2D method was adapted for 3D image segmentation, and automated 3D methods to calculate strain, twist, and torsion were employed. A scan protocol that covered the majority of the left ventricle in a scan time of less than 25 minutes was developed, and seven healthy C57Bl/6 mice were studied.</p> <p>Results</p> <p>Using these methods, multiphase normal and shear strains were measured, as were myocardial twist and torsion. Peak end-systolic values for the normal strains at the mid-ventricular level were 0.29 ± 0.17, -0.13 ± 0.03, and -0.18 ± 0.14 for <it>E_rr</it>, <it>E_cc</it>, and <it>E_ll</it>, respectively. Peak end-systolic values for the shear strains were 0.00 ± 0.08, 0.04 ± 0.12, and 0.03 ± 0.07 for <it>E_rc</it>, <it>E_rl</it>, and <it>E_cl</it>, respectively. The peak end-systolic normalized torsion was 5.6 ± 0.9°.</p> <p>Conclusions</p> <p>Using a 3D cine DENSE sequence tailored for cardiac imaging in mice at 7 T, a comprehensive assessment of 3D myocardial mechanics can be achieved with a scan time of less than 25 minutes and an image analysis time of approximately 1 hour.</p