Discrete-time pilot model

Pilot behavior is considered as a discrete-time process where the decision making has a sequential nature. This model differs from both the quasilinear model which follows from classical control theory and from the optimal control model which considers the human operator as a Kalman estimator-predictor. An additional factor considered is that the pilot's objective may not be adequately formulated as a quadratic cost functional to be minimized, but rather as a more fuzzy measure of the closeness with which the aircraft follows a reference trajectory. All model parameters, in the digital program simulating the pilot's behavior, were successfully compared in terms of standard-deviation and performance with those of professional pilots in IFR configuration. The first practical application of the model was in the study of its performance degradation when the aircraft model static margin decreases

Discrete time modeling of heavy transport plane pilot behavior

The desire to improve flight safety leads to a classification of various flight troubles in three groups: (1) troubles from sensitivity to flight disturbances, (2) maneuverability troubles (whenever a correction maneuver induces an unexpected deviation on another parameter), and (3) pilot troubles (pilot overload when required attention is excessive or underload entailing a loss of vigilance). Sensitivity to disturbances and maneuverability of a given aircraft may be evaluated from the early design stage. Evaluation of the pilot behavior, however, may be realized only in actual flight or with a flight simulator, that is quite late in the development period. For this reason, it is desirable to have available, at the design stage, a model of the pilot behavior to command the differential system describing the envisioned aircraft. This aim implies two major requirements. First, the program must be compatible with a wide range of possible aircraft designs; ideally, the program should be self-learning. Second, mental load and overall pilot performance must be modeled

The high-pressure behavior of CaMoO4

We report a high-pressure study of tetragonal scheelite-type CaMoO4 up to 29 GPa. In order to characterize its high-pressure behavior, we have combined Raman and optical-absorption measurements with density-functional theory calculations. We have found evidence of a pressure-induced phase transition near 15 GPa. Experiments and calculations agree in assigning the high-pressure phase to a monoclinic fergusonite-type structure. The reported results are consistent with previous powder x-ray-diffraction experiments, but are in contradiction with the conclusions obtained from earlier Raman measurements, which support the existence of more than one phase transition in the pressure range covered by our studies. The observed scheelite-fergusonite transition induces significant changes in the electronic band gap and phonon spectrum of CaMoO4. We have determined the pressure evolution of the band gap for the low- and high-pressure phases as well as the frequencies and pressure dependences of the Raman-active and infrared-active modes. In addition, based upon calculations of the phonon dispersion of the scheelite phase, carried out at a pressure higher than the transition pressure, we propose a possible mechanism for the reported phase transition. Furthermore, from the calculations we determined the pressure dependence of the unit-cell parameters and atomic positions of the different phases and their room-temperature equations of state. These results are compared with previous experiments showing a very good agreement. Finally, information on bond compressibility is reported and correlated with the macroscopic compressibility of CaMoO4. The reported results are of interest for the many technological applications of this oxide.Comment: 36 pages, 10 figures, 8 table

Dysphonia secondary to traumatic avulsion of the vocal fold in infants

Objective: Airway compromise due to paediatric intubation injuries is well documented; however, intubation injuries may also cause severe voice disorders. We report our experience and review the world literature on the voice effects of traumatic paediatric intubation. Case series: We report five cases of children referred to Great Ormond Street Hospital for Children who suffered traumatic avulsion of the vocal fold at the time of, or secondary to, endotracheal intubation. All children had significant dysphonia and underwent specialist voice therapy. Conclusions: The mechanisms of injury, risk factors and management of the condition are discussed. Children suffering traumatic intubation require follow up throughout childhood and beyond puberty as their vocal needs and abilities change. At the time of writing, none of the reported patients had yet undergone reconstructive or medialisation surgery. However, regular specialist voice therapy evaluation is recommended for such patients, with consideration of phonosurgical techniques including injection laryngoplasty or thyroplasty

Search for the radion using the ATLAS detector

The possibility of observing the radion using the ATLAS detector at LHC is investigated. Studies on searches for the Standard Model Higgs with the ATLAS detector are re-interpreted to obtain limits on radion decay to gamma-gamma and ZZ(*). The observability of radion decays into Higgs pairs, which subsequently decay into gamma-gamma+b-bbar or tau-tau+b-bbar is then estimate

Genetic drift at expanding frontiers promotes gene segregation

Competition between random genetic drift and natural selection plays a central role in evolution: Whereas non-beneficial mutations often prevail in small populations by chance, mutations that sweep through large populations typically confer a selective advantage. Here, however, we observe chance effects during range expansions that dramatically alter the gene pool even in large microbial populations. Initially well-mixed populations of two fluorescently labeled strains of Escherichia coli develop well-defined, sector-like regions with fractal boundaries in expanding colonies. The formation of these regions is driven by random fluctuations that originate in a thin band of pioneers at the expanding frontier. A comparison of bacterial and yeast colonies (Saccharomyces cerevisiae) suggests that this large-scale genetic sectoring is a generic phenomenon that may provide a detectable footprint of past range expansions.Comment: Please visit http://www.pnas.org/content/104/50/19926.abstract for published articl

Next-to-leading order QCD predictions for the hadronic WHWH+jet production

We calculate the next-to-leading order(NLO) QCD corrections to the $WH^0$ production in association with a jet at hadron colliders. We study the impacts of the complete NLO QCD radiative corrections to the integrated cross sections, the scale dependence of the cross sections, and the differential cross sections ($\frac{d \sigma}{d\cos\theta}$, $\frac{d \sigma}{dp_T}$) of the final $W$-, Higgs-boson and jet. We find that the corrections significantly modify the physical observables, and reduce the scale uncertainty of the LO cross section. Our results show that by applying the inclusive scheme with $p_{T,j}^{cut}=20 GeV$ and taking $m_H=120 GeV$, $\mu=\mu_0\equiv\frac{1}{2}(m_W+m_H)$, the K-factor is 1.15 for the process $p\bar p \to W^{\pm}H^0j+X$ at the Tevatron, while the K-factors for the processes $pp \to W^-H^0j+X$ and $pp \to W^+H^0j+X$ at the LHC are 1.12 and 1.08 respectively. We conclude that to understand the hadronic associated $WH^0$ production, it is necessary to study the NLO QCD corrections to $WH^0j$ production process which is part of the inclusive $WH^0$ production.Comment: 26 pages, 27 figures, accepted by Phys. Rev.

Measurement of Dielectric Suppression of Bremsstrahlung

In 1953, Ter-Mikaelian predicted that the bremsstrahlung of low energy photons in a medium is suppressed because of interactions between the produced photon and the electrons in the medium. This suppression occurs because the emission takes place over on a long distance scale, allowing for destructive interference between different instantaneous photon emission amplitudes. We present here measurements of bremsstrahlung cross sections of 200 keV to 20 MeV photons produced by 8 and 25 GeV electrons in carbon and gold targets. Our data shows that dielectric suppression occurs at the predicted level, reducing the cross section up to 75 percent in our data.Comment: 11 pages, format is postscript file, gzip-ed, uuencode-e

25(OH)D3-enriched or fortified foods are more efficient at tackling inadequate vitamin D status than vitamin D3

The ability to synthesise sufficient vitamin D through sunlight in human subjects can be limited. Thus, diet has become an important contributor to vitamin D intake and status; however, there are only a few foods (e.g. egg yolk, oily fish) naturally rich in vitamin D. Therefore, vitamin D-enriched foods via supplementing the animals’ diet with vitamin D or vitamin D fortification of foods have been proposed as strategies to increase vitamin D intake. Evidence that cholecalciferol (vitamin D3) and calcifediol (25(OH)D3) content of eggs, fish and milk increased in response to vitamin D3 supplementation of hens, fish or cows’ diets was identified when vitamin D-enrichment studies were reviewed. However, evidence from supplementation studies with hens showed only dietary 25(OH)D3, not vitamin D3 supplementation, resulted in a pronounced increase of 25(OH)D3 in the eggs. Furthermore, evidence from randomised controlled trials indicated that a 25(OH)D3 oral supplement could be absorbed faster and more efficiently raise serum 25(OH)D concentration compared with vitamin D3 supplementation. Moreover, evidence showed the relative effectiveness of increasing vitamin D status using 25(OH)D3 varied between 3·13 and 7·14 times that of vitamin D3, probably due to the different characteristics of the investigated subjects or study design. Therefore, vitamin D-enrichment or fortified foods using 25(OH)D3 would appear to have advantages over vitamin D3. Further wellcontrolled studies are needed to assess the effects of 25(OH)D3 enriched or fortified foods in the general population and clinical patients