Subsonic pitch-up alleviation on a 74 deg delta wing

Fixed leading-edge devices were investigated for alleviating the low speed pitch-up and longitudinal instability of a 74 deg delta wing model. In wind-tunnel tests, Pylon Vortex Generators were shown to be highly effective, compared to leading-edge fences and slots, in raising the pitch-up angle of attack from 8 deg to 28 deg. The subsonic drag penalty was negligible

Experimental study of delta wing leading-edge devices for drag reduction at high lift

The drag reduction devices selected for evaluation were the fence, slot, pylon-type vortex generator, and sharp leading-edge extension. These devices were tested on a 60 degree flatplate delta (with blunt leading edges) in the Langley Research Center 7- by 10-foot high-speed tunnel at low speed and to angles of attack of 28 degrees. Balance and static pressure measurements were taken. The results indicate that all the devices had significant drag reduction capability and improved longitudinal stability while a slight loss of lift and increased cruise drag occurred

Simulated lumped-parameter system reduced-order adaptive control studies

Two methods of interpreting the misbehavior of reduced order adaptive controllers are discussed. The first method is based on system input-output description and the second is based on state variable description. The implementation of the single input, single output, autoregressive, moving average system is considered

RECIPROCAL RECURRENT SELECTION FOR 21-DAY LITTER WEIGHT OF CROSSBRED GILTS. I. SELECTION APPLIED AND GENETIC CHANGE IN REPRODUCTION OF CROSSBRED GILTS

Six cycles of reciprocal recurrent selection (RRS) between Line 8 (Duroc) and Line 9 (Beltsville No. 1) were completed at the Fort Reno Livestock Research Center, E1 Reno, Oklahoma. A randomly mated control line was maintained. Each cycle of selection required three seasons. Selection of purebred pigs (born in the second season) was based on the mean 21-d litter weight of their maternal and paternal half-sib crossbred gilts that were born in the first season and farrowed in the third season (XB21DLWT). On the average, 5.8 maternal and paternal half-sib gilts contributed to the mean XB21DLWT for each purebred individual. The average potential selection differential for XB21DLWT was 5.64 kg, but only 70.2% of this value was realized in the initial selection (3.95 kg). Disease problems and unsoundness were the primary reasons for this discrepancy. The potential, initial, final and weighted final standardized selection differentials for females averaged 61, 60, 55 and 47%, respectively, of the corresponding differentials for males. Standardized selection differentials were similar for Line 8 and Line 9. The estimate of realized heritability for XB21DLWT was .076 ± .319 for the average of 8 x 9 and 9 x 8 gilts. Environmental trends, estimated from control data, were not significant for any of the traits evaluated. The genetic change in reproductive ability of 8 x 9, 9 x 8 and their unweighted average was estimated by regressing the deviation of the line mean from the control mean on generation number. In general, estimates of genetic change for litter size, litter weight and average pig weight/litter at 0, 21 and 42 d of age were not significant, but all estimates were favorable. The estimated genetic change for 21-d litter weight was 1.04 ± 1.25 kg/cycle of selection. Based on these results and considering the complexity of RRS, the increase in generation interval and the expected decline in purebred performance that theoretically should accompany successful RRS, it seems doubtful that RRS can be more beneficial than selection based on purebred performance as a method to improve productivity of crossbred gilts

RECIPROCAL RECURRENT SELECTION FOR 21-DAY LITTER WEIGHT OF CROSSBRED GILTS. II. REPRODUCTIVE PERFORMANCE OF PUREBRED FEMALES PRODUCING PUREBRED AND TWO-WAY CROSS LITTERS AND PERFORMANCE OF PUREBRED AND CROSSBRED PIGS

This paper reports estimates of correlated genetic change in reproductive performance of purebred gilts producing two-way cross litters and purebred sows producing purebred litters as well as postweaning performance of two-way cross and purebred pigs produced during reciprocal recurrent selection (RRS) between Line 8 (Duroc) and Line 9 (Beltsville No. 1) for 21-d litter weight production of crossbred gilts. A randomly mated control line developed from a crossbred foundation was maintained to monitor environmental change. Data were adjusted for age of dam, inbreeding of dam, inbreeding of litter (or pig) and linear and quadratic effects of day born within season. The traits evaluated were: litter size, litter weight and average pig weight/litter at birth and weaning (42 d); postweaning average daily gain; age at 90.7 kg and backfat thickness at 90.7 kg. Two data sets were analyzed; the first set included seven seasons of data with purebred gilts producing two-way cross litters, and the second set included seven seasons of data with purebred sows producing purebred litters. No estimates of environmental trend were significant in either set of data. In the first data set, only the estimate of genetic change in backfat thickness of two-way cross pigs was significant and it was in the desired direction. All other estimates were small and did not approach significance. In the second data set, estimates of genetic trend were greater in Line 9 than in Line 8. Estimates of genetic trend in Line 9 were significant for average pig weight at birth, age at 90.7 kg and backfat probe at 90.7 kg, and approached significance for litter size at weaning and average daily gain. The estimates were undesirable for preweaning traits and desirable for postweaning traits. The estimates of genetic trend in Line 8 were of the same sign as those in Line 9, but only the estimate for backfat thickness was significant. The decrease in size of purebred litters in Line 9, and to some degree Line 8, suggests an accelerated accumulation of homozygosity beyond that accounted for by adjustment for pedigree inbreeding. The fact that Line 9 showed a greater decrease than Line 8 suggests that most of the increase in level of reproduction of crossbred gilts may have resulted from genetic change in Line 9 rather than Line 8, or that favorable alleles were being fixed in Line 8 and unfavorable alleles in Line 9

Indication, from Pioneer 10/11, Galileo, and Ulysses Data, of an Apparent Anomalous, Weak, Long-Range Acceleration

Radio metric data from the Pioneer 10/11, Galileo, and Ulysses spacecraft indicate an apparent anomalous, constant, acceleration acting on the spacecraft with a magnitude $\sim 8.5\times 10^{-8}$ cm/s$^2$, directed towards the Sun. Two independent codes and physical strategies have been used to analyze the data. A number of potential causes have been ruled out. We discuss future kinematic tests and possible origins of the signal.Comment: Revtex, 4 pages and 1 figure. Minor changes for publicatio

HD 145263: Spectral Observations of Silica Debris Disk Formation via Extreme Space Weathering?

We report here time domain infrared spectroscopy and optical photometry of the HD145263 silica-rich circumstellar disk system taken from 2003 through 2014. We find an F4V host star surrounded by a stable, massive 1e22 - 1e23 kg (M_Moon to M_Mars) dust disk. No disk gas was detected, and the primary star was seen rotating with a rapid ~1.75 day period. After resolving a problem with previously reported observations, we find the silica, Mg-olivine, and Fe-pyroxene mineralogy of the dust disk to be stable throughout, and very unusual compared to the ferromagnesian silicates typically found in primordial and debris disks. By comparison with mid-infrared spectral features of primitive solar system dust, we explore the possibility that HD 145263's circumstellar dust mineralogy occurred with preferential destruction of Fe-bearing olivines, metal sulfides, and water ice in an initially comet-like mineral mix and their replacement by Fe-bearing pyroxenes, amorphous pyroxene, and silica. We reject models based on vaporizing optical stellar megaflares, aqueous alteration, or giant hypervelocity impacts as unable to produce the observed mineralogy. Scenarios involving unusually high Si abundances are at odds with the normal stellar absorption near-infrared feature strengths for Mg, Fe, and Si. Models involving intense space weathering of a thin surface patina via moderate (T < 1300 K) heating and energetic ion sputtering due to a stellar superflare from the F4V primary are consistent with the observations. The space weathered patina should be reddened, contain copious amounts of nanophase Fe, and should be transient on timescales of decades unless replenished.Comment: 41 Pages, 5 Figures, 5 Tables, Accepted for publication in the Astrophysical Journa

Calculation of AGARD Wing 445.6 Flutter Using Navier-Stokes Aerodynamics

An unsteady, 3D, implicit upwind Euler/Navier-Stokes algorithm is here used to compute the flutter characteristics of Wing 445.6, the AGARD standard aeroelastic configuration for dynamic response, with a view to the discrepancy between Euler characteristics and experimental data. Attention is given to effects of fluid viscosity, structural damping, and number of structural model nodes. The flutter characteristics of the wing are determined using these unsteady generalized aerodynamic forces in a traditional V-g analysis. The V-g analysis indicates that fluid viscosity has a significant effect on the supersonic flutter boundary for this wing

The molecular characterisation of Escherichia coli K1 isolated from neonatal nasogastric feeding tubes

Background: The most common cause of Gram-negative bacterial neonatal meningitis is E. coli K1. It has a mortality rate of 10–15%, and neurological sequelae in 30– 50% of cases. Infections can be attributable to nosocomial sources, however the pre-colonisation of enteral feeding tubes has not been considered as a specific risk factor. Methods: Thirty E. coli strains, which had been isolated in an earlier study, from the residual lumen liquid and biofilms of neonatal nasogastric feeding tubes were genotyped using pulsed-field gel electrophoresis, and 7-loci multilocus sequence typing. Potential pathogenicity and biofilm associated traits were determined using specific PCR probes, genome analysis, and in vitro tissue culture assays. Results: The E. coli strains clustered into five pulsotypes, which were genotyped as sequence types (ST) 95, 73, 127, 394 and 2076 (Achman scheme). The extra-intestinal pathogenic E. coli (ExPEC) phylogenetic group B2 ST95 serotype O1:K1:NM strains had been isolated over a 2 week period from 11 neonates who were on different feeding regimes. The E. coli K1 ST95 strains encoded for various virulence traits associated with neonatal meningitis and extracellular matrix formation. These strains attached and invaded intestinal, and both human and rat brain cell lines, and persisted for 48 h in U937 macrophages. E. coli STs 73, 394 and 2076 also persisted in macrophages and invaded Caco-2 and human brain cells, but only ST394 invaded rat brain cells. E. coli ST127 was notable as it did not invade any cell lines. Conclusions: Routes by which E. coli K1 can be disseminated within a neonatal intensive care unit are uncertain, however the colonisation of neonatal enteral feeding tubes may be one reservoir source which could constitute a serious health risk to neonates following ingestion