An exploratory study of api changes and usages based on apache and eclipse ecosystems

Frameworks are widely used in modern software development to reduce development costs. They are accessed through their Application Programming Interfaces (APIs), which specify the contracts with client programs. When frameworks evolve, API backward-compatibility cannot always be guaranteed and client programs must upgrade to use the new releases. Because framework upgrades are not cost-free, observing API changes and usages together at fine-grained levels is necessary to help developers understand, assess, and forecast the cost of each framework upgrade. Whereas previous work studied API changes in frameworks and API usages in client programs separately, we analyse and classify API changes and usages together in 22 framework releases from the Apache and Eclipse ecosystems and their client programs. We find that (1) missing classes and methods happen more often in frameworks and affect client programs more often than the other API change types do, (2) missing interfaces occur rarely in frameworks but affect client programs often, (3) framework APIs are used on average in 35 % of client classes and interfaces, (4) most of such usages could be encapsulated locally and reduced in number, and (5) about 11 % of APIs usages could cause ripple effects in client programs when these APIs change. Based on these findings, we provide suggestions for developers and researchers to reduce the impact of API evolution through language mechanisms and design strategies.     

Variable-coherence tomography for inverse scattering problems

We propose a technique for determining the pair-correlation function of a quasi-homogeneous medium. The method uses the variation of the spatial-coherence properties of the incident beam to generate two separate volumes of coherence where the field is correlated. Using this specially prepared beam, we reconstruct experimentally the correlation function of a scattering potential by recording the scattered intensity in only one direction.     

Modeling Steady Acoustic Fields Bounded in Cavities with Geometrical Imperfections

A mathematical method is derived within the framework of classical Lagrangian field theory, which is suitable for the determination of the eigenstates of acoustic resonators of nearly spherical shape. The method is based on the expansion of the Helmholtz differential operator and the boundary condition in a power series of a small geometrical perturbation parameter e{epsilon} . The method extends to orders higher than e²{epsilon^2} the calculation of the perturbed acoustic eigenvalues, which was previously limited by the use of variational formalism and the methods of Morse and Ingard. A specific example is worked out for radial modes of a prolate spheroid, with the frequency perturbation calculated to order e³{epsilon^3} . A possible strategy to tackle the problem of calculating the acoustic eigenvalues for cavities presenting non-smooth geometrical imperfections is also described.     

Solid–Liquid Equilibria for the CO<Subscript>2</Subscript> + R23 and N<Subscript>2</Subscript>O + R23 Systems

A recently built experimental setup was employed for the estimation of the solid–liquid equilibria of alternative refrigerant systems. In this paper two binaries, i.e., carbon dioxide + trifluoromethane (CO₂ + R23) and nitrous oxide + trifluoromethane (N₂O + R23), were studied down to temperatures of 117 K. In order to check the reliability of the apparatus, the triple points of the pure fluids contained in the mixture were measured, revealing good consistency with the literature. The results obtained for the mixtures were interpreted by means of the Schröder equation.     

Polydialkylphosphazenes: New synthetic efforts and protonation reactions

Some dialkyl-or diaryl-phosphoranimines are so thermally stable that their thermal polymerization cannot be pursued: it follows that an alternative route to the synthesis of said polymers is to be found. The polymerization ofN-silyldiethylphosphoranimine with the aid of anionic initiators was studied. This reaction. compared with thermal polymerization. proceeded at a lower temperature and with a shorter completion time. Low molecular weights and often bimodal distributions were found.M _m values obtained with Bu₄NF and NaOPh were in the range 1000 10.000, with very narrow polydispersities. Since symmetrical disubstituted polyalkylphosphazenes with alkyl chains from C₂ up to C₈ are insoluble in organic solvents, their solution characterization in usual solvents was prevented. For this purpose, protonation reactions with organic and mineral acids were studied. The protonated polymers were found to be soluble in organic acids and in water, NMR spectra were registered. The molecular weights of the polymers were determined in 20% (v/v) acetic acid. The method, tested on samples of polydimethylphosphazene whose molecular weight was determined independently by membrane osmometry in chloroform solutions, was found to be reliable.Presented at the 1st Italian Workshop on Cyclo- and Polytphosphazene Materials. February 15, 16, 1996, at the CNR Research Area in Padova, Italy.     

Natural Abundance Carbon Isotopic Analysis Indicates the Equal Contribution of Local Synthesis and Plasma Uptake to Palmitate Levels in the Mouse Brain

Saturated fatty acids are the most abundant fatty acids in the brain, however, there has been some debate regarding the ability of intact dietary saturated fatty acids to be incorporated into the brain. In the present study, we use compound specific isotope analysis to measure the natural abundance carbon isotopic signature of brain, liver, and blood palmitic acid (PAM) and compare it to the dietary PAM and sugar isotopic signatures to calculate the relative contribution of both the incorporation of intact and endogenously synthesized PAM to these pools. Mice were equilibrated to the study diet, and extracted fatty acids were analyzed with gas chromatography isotope ratio mass spectrometry to determine the carbon isotopic signature of PAM (δ¹³C_PAM). Liver, serum total, and serum unesterified fatty acid δ¹³C_PAM ranged between ?20.6 and ?21.1 mUr and were approximately 8.5 mUr more enriched in ¹³C when compared to the dietary PAM signature. Brain δ¹³C_PAM was found to be more enriched than liver or blood pools (?16.7 ± 0.2 mUr, mean ± SD). Two end‐member‐mixed modeling using the carbon isotopic signature of dietary PAM and dietary sugars determined the contribution of synthesis to the total tissue PAM pool to range between 44% and 48%. This suggests that endogenous synthesis and dietary PAM are near equal contributors to brain, liver, and blood PAM pools. In conclusion, our data provide evidence that brain PAM levels are maintained by both local endogenous synthesis and through the uptake of intact PAM from the blood.     

Microwave power amplifiers for space systems

This paper addresses both solid state power amplifiers (sspas) and travelling wave tube amplifiers (twtas), highlighting their capabilities, drawbacks and future developments, for space systems. These two technologies are complementary and will coexist in future pay loads.     

Micro gas turbine thermodynamic and economic analysis up to 500 kWe size

In this paper a thermoeconomic analysis and optimization of micro gas turbines (MGT) up to 500 kWe is presented. This analysis is strongly related to the need of minimizing specific capital cost, still high for MGT large market penetration, and optimizing MGT size to match market needs.     

Digital Detection of Single Virus Particles by Multi-Spot,Label-Free Imaging Biosensor on Anti-Reflective Glass

Rapid detection of whole virus particles in biological or environmental samples represents an unmet need for the containment of infectious diseases. Here, an optical device enabling the enumeration of single virion particles binding on antibody or aptamers immobilized on a surface with anti-reflective coating is described. In this regime, nanoparticles adhering to the sensor surface provide localized contributions to the reflected field that become detectable because of their mixing with the interfering waves in the reflection direction. Thus, these settings are exploited to realize a scan-free, label-free, micro-array-type digital assay on a disposable cartridge, in which the virion counting takes place in wide field-of-view imaging. With this approach we could quantify, by enumeration, different variants of SARS-CoV-2 virions interacting with antibodies and aptamers immobilized on different spots. For all tested variants, the aptamers showed larger affinity but lower specificity relative to the antibodies. It is found that the combination of different probes on the same surface enables increasing specificity of detection and dynamic range.