Evolution of Ada technology in the flight dynamics area: Design phase analysis

The software engineering issues related to the use of the Ada programming language during the design phase of an Ada project are analyzed. Discussion shows how an evolving understanding of these issues is reflected in the design processes of three generations of Ada projects

Evolution of Ada technology in the flight dynamics area: Implementation/testing phase analysis

An analysis is presented of the software engineering issues related to the use of Ada for the implementation and system testing phases of four Ada projects developed in the flight dynamics area. These projects reflect an evolving understanding of more effective use of Ada features. In addition, the testing methodology used on these projects has changed substantially from that used on previous FORTRAN projects

Evolving impact of Ada on a production software environment

Many aspects of software development with Ada have evolved as our Ada development environment has matured and personnel have become more experienced in the use of Ada. The Software Engineering Laboratory (SEL) has seen differences in the areas of cost, reliability, reuse, size, and use of Ada features. A first Ada project can be expected to cost about 30 percent more than an equivalent FORTRAN project. However, the SEL has observed significant improvements over time as a development environment progresses to second and third uses of Ada. The reliability of Ada projects is initially similar to what is expected in a mature FORTRAN environment. However, with time, one can expect to gain improvements as experience with the language increases. Reuse is one of the most promising aspects of Ada. The proportion of reusable Ada software on our Ada projects exceeds the proportion of reusable FORTRAN software on our FORTRAN projects. This result was noted fairly early in our Ada projects, and experience shows an increasing trend over time

First application of Markov chain Monte Carlo-based Bayesian data analysis to the Doppler-shift attenuation method

Motivated primarily by the large uncertainties in the thermonuclear rate of the 30P(p,γ)31S reaction that limit our understanding of classical novae, we carried out lifetime measurements of 31S excited states using the Doppler Shift Lifetimes (DSL2) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility. The 31S excited states were populated by the 3He(32S,α)31S reaction. The deexcitation γ rays were detected by a clover-type high-purity germanium detector in coincidence with the α particles detected by a silicon detector telescope. We have applied modern Markov chain Monte Carlo-based Bayesian statistical techniques to perform lineshape analyses of Doppler-shift attenuation method γ-ray data for the first time. We have determined the lifetimes of the two lowest-lying 31S excited states. First experimental upper limits on the lifetimes of four higher-lying states have been obtained. The experimental results were compared to shell-model calculations using five universal sd-shell Hamiltonians. Evidence for γ rays originating from the astrophysically important Jπ=3/2+, 260-keV 30P(p,γ)31S resonance with an excitation energy of Ex=6390.2(7) keV in 31S has also been observed, although strong constraints on the lifetime will require better statistics

Diameters in preferential attachment models

In this paper, we investigate the diameter in preferential attachment (PA-) models, thus quantifying the statement that these models are small worlds. The models studied here are such that edges are attached to older vertices proportional to the degree plus a constant, i.e., we consider affine PA-models. There is a substantial amount of literature proving that, quite generally, PA-graphs possess power-law degree sequences with a power-law exponent \tau>2. We prove that the diameter of the PA-model is bounded above by a constant times \log{t}, where t is the size of the graph. When the power-law exponent \tau exceeds 3, then we prove that \log{t} is the right order, by proving a lower bound of this order, both for the diameter as well as for the typical distance. This shows that, for \tau>3, distances are of the order \log{t}. For \tau\in (2,3), we improve the upper bound to a constant times \log\log{t}, and prove a lower bound of the same order for the diameter. Unfortunately, this proof does not extend to typical distances. These results do show that the diameter is of order \log\log{t}. These bounds partially prove predictions by physicists that the typical distance in PA-graphs are similar to the ones in other scale-free random graphs, such as the configuration model and various inhomogeneous random graph models, where typical distances have been shown to be of order \log\log{t} when \tau\in (2,3), and of order \log{t} when \tau>3

Upper bounds for number of removed edges in the Erased Configuration Model

Models for generating simple graphs are important in the study of real-world complex networks. A well established example of such a model is the erased configuration model, where each node receives a number of half-edges that are connected to half-edges of other nodes at random, and then self-loops are removed and multiple edges are concatenated to make the graph simple. Although asymptotic results for many properties of this model, such as the limiting degree distribution, are known, the exact speed of convergence in terms of the graph sizes remains an open question. We provide a first answer by analyzing the size dependence of the average number of removed edges in the erased configuration model. By combining known upper bounds with a Tauberian Theorem we obtain upper bounds for the number of removed edges, in terms of the size of the graph. Remarkably, when the degree distribution follows a power-law, we observe three scaling regimes, depending on the power law exponent. Our results provide a strong theoretical basis for evaluating finite-size effects in networks

Meta-Analysis of Yield Response of Hybrid Field Corn to Foliar Fungicides in the U.S. Corn Belt

The use of foliar fungicides on field corn has increased greatly over the past 5 years in the United States in an attempt to increase yields, despite limited evidence that use of the fungicides is consistently profitable. To assess the value of using fungicides in grain corn production, random-effects meta-analyses were performed on results from foliar fungicide experiments conducted during 2002 to 2009 in 14 states across the United States to determine the mean yield response to the fungicides azoxystrobin, pyraclostrobin, propiconazole + trifloxystrobin, and propiconazole + azoxystrobin. For all fungicides, the yield difference between treated and nontreated plots was highly variable among studies. All four fungicides resulted in a significant mean yield increase relative to the nontreated plots (P \u3c 0.05). Mean yield difference was highest for propiconazole + trifloxystrobin (390 kg/ha), followed by propiconazole + azoxystrobin (331 kg/ha) and pyraclostrobin (256 kg/ha), and lowest for azoxystrobin (230 kg/ha). Baseline yield (mean yield in the nontreated plots) had a significant effect on yield for propiconazole + azoxystrobin (P \u3c 0.05), whereas baseline foliar disease severity (mean severity in the nontreated plots) significantly affected the yield response to pyraclostrobin, propiconazole + trifloxystrobin, and propiconazole + azoxystrobin but not to azoxystrobin. Mean yield difference was generally higher in the lowest yield and higher disease severity categories than in the highest yield and lower disease categories. The probability of failing to recover the fungicide application cost (ploss) also was estimated for a range of grain corn prices and application costs. At the 10-year average corn grain price of $0.12/kg ($2.97/bushel) and application costs of $40 to 95/ha, ploss for disease severity \u3c5% was 0.55 to 0.98 for pyraclostrobin, 0.62 to 0.93 for propiconazole + trifloxystrobin, 0.58 to 0.89 for propiconazole + azoxystrobin, and 0.91 to 0.99 for azoxystrobin. When disease severity was \u3e5%, the corresponding probabilities were 0.36 to 95, 0.25 to 0.69, 0.25 to 0.64, and 0.37 to 0.98 for the four fungicides. In conclusion, the high ploss values found in most scenarios suggest that the use of these foliar fungicides is unlikely to be profitable when foliar disease severity is low and yield expectation is high

Identification of the New Isotope \u3csup\u3e244\u3c/sup\u3eMd

In an experiment performed at Lawrence Berkeley National Laboratory\u27s 88-inch cyclotron, the isotope Md244 was produced in the Bi209(Ar40,5n) reaction. Decay properties of Md244 were measured at the focal plane of the Berkeley Gas-filled Separator, and the mass number assignment of A=244 was confirmed with the apparatus for the identification of nuclide A. The isotope Md244 is reported to have one, possibly two, α-decaying states with α energies of 8.66(2) and 8.31(2) MeV and half-lives of 0.4-0.1+0.4 and ∼6 s, respectively. Additionally, first evidence of the α decay of Bk236 was observed and is reported

Decay of the High-K Isomeric State to a Rotational Band in 257Rf

The 257Rf isotope has been populated via the 208Pb(50Ti, n) fusion-evaporation reaction and delayed gamma-ray and electron decay spectroscopy has been performed. The existence of a high-K isomeric state in 257Rf has been confirmed. The isomeric state decays into a rotational band based on the 11/2(-)[725] excitation, which was observed up to spin of (23/2(-)). Three multipolarity-E1 gamma transitions depopulating the isomeric state have been observed, which fixes the spin for that state to (21/2(+)). This assignment agrees with theoretical predictions calculated with the microscopic-macroscopic approach, which suggest the isomeric state to be formed by coupling an unpaired 11/2(-)[725] quasineutron to the (1/2(-)[521] circle times 9/2(+)[624])(5)- two-quasiproton state. The same two-quasiproton excitation is possible for the lowest isomer in 256Rf