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Floods are the leading cause of natural disaster damages in the United States, with billions of dollars incurred every year in the form of government payouts, property damages, and agricultural losses. The Federal Emergency Management Agency oversees the delineation of floodplains to mitigate damages, but disparities exist between locations designated as high risk and where flood damages occur due to land use and climate changes and incomplete floodplain mapping. We harnessed publicly available geospatial datasets and random forest algorithms to analyze the spatial distribution and underlying drivers of flood damage probability (FDP) caused by excessive rainfall and overflowing water bodies across the conterminous United States. From this, we produced the first spatially complete map of FDP for the nation, along with spatially explicit standard errors for four selected cities. We trained models using the locations of historical reported flood damage events (n = 71 434) and a suite of geospatial predictors (e.g. flood severity, climate, socio-economic exposure, topographic variables, soil properties, and hydrologic characteristics). We developed independent models for each hydrologic unit code level 2 watershed and generated a FDP for each 100 m pixel. Our model classified damage or no damage with an average area under the curve accuracy of 0.75; however, model performance varied by environmental conditions, with certain land cover classes (e.g. forest) resulting in higher error rates than others (e.g. wetlands). Our results identified FDP hotspots across multiple spatial and regional scales, with high probabilities common in both inland and coastal regions. The highest flood damage probabilities tended to be in areas of low elevation, in close proximity to streams, with extreme precipitation, and with high urban road density. Given rapid environmental changes, our study demonstrates an efficient approach for updating FDP estimates across the nation.

The present research aims to evaluate the physicochemical variables involved in the anaerobic digestion process to produce methane from manure on an agricultural farm; the farm has 2 equines that generate 12 Kg of manure per day. A manure sample was collected, and the following physicochemical parameters were determined: total solids, volatile solids, chemical oxygen demand, and pH. A tubular household biodigester was then implemented, consisting mainly of a polyethylene geomembrane that stores the organic matter and in which anaerobic digestion takes place. The performance of the biodigester was determined by the removal of organic matter quantified by volatile solids and chemical oxygen demand in the biodigester influent and digestate, of which removal of 82% of volatile solids and 74% of chemical oxygen demand was achieved. The average biogas production was 0.5 m3/day, and its lower heating value was 26,000 kJ/m3. The pH level of the biodigester was within the range of 6-7, in order to keep the methanogenic bacteria active, in charge of carrying out physicochemical process that guarantees anaerobic digestion and thus, the production of biogas.

Alloying enables engineering of the electronic structure of semiconductors for optoelectronic applications. Due to their similar lattice parameters, the two-dimensional semiconducting transition metal dichalcogenides of the MoWSeS group (MX2 where M = Mo or W and X = S or Se) can be grown as high-quality materials with low defect concentrations. Here we investigate the atomic and electronic structure of Mo(1−x)W x S2 alloys using a combination of high-resolution experimental techniques and simulations. Analysis of the Mo and W atomic positions in these alloys, grown by chemical vapour transport, shows that they are randomly distributed, consistent with Monte Carlo simulations that use interaction energies determined from first-principles calculations. Electronic structure parameters are directly determined from angle resolved photoemission spectroscopy measurements. These show that the spin–orbit splitting at the valence band edge increases linearly with W content from MoS2 to WS2, in agreement with linear-scaling density functional theory predictions. The spin–orbit splitting at the conduction band edge is predicted to reduce to zero at intermediate compositions. Despite this, polarisation-resolved photoluminescence spectra on monolayer Mo0.5W0.5S2 show significant circular dichroism, indicating that spin-valley locking is retained. These results demonstrate that alloying is an important tool for controlling the electronic structure of MX2 for spintronic and valleytronic applications.

The aim of this research is to use Artificial Neural Networks (ANN) to dimension structural elements in regular 6-storey buildings. The necessary data for the training of the algorithm was elaborated manually with the help of the ETABS software, these were 30 buildings of reinforced concrete with a system of structural walls. The configuration and training of the neural network was carried out in the MATLAB software. The validation was carried out in an additional analyzed building in which the concrete savings were calculated, and the requirements of the current regulations were verified. Finally, the dimensioning obtained with the neural network generated a reduction of more than 10% in the total volume of concrete used in a 6-level building and establishes that the algorithm used provides effective results for an optimal design.

A high-performance III–V quantum-dot (QD) laser monolithically grown on Si is one of the most promising candidates for commercially viable Si-based lasers. Great efforts have been made to overcome the challenges due to the heteroepitaxial growth, including threading dislocations and anti-phase boundaries, by growing a more than 2 µm thick III–V buffer layer. However, this relatively thick III–V buffer layer causes the formation of thermal cracks in III–V epi-layers, and hence a low yield of Si-based optoelectronic devices. In this paper, we demonstrate a usage of thin Ge buffer layer to replace the initial part of GaAs buffer layer on Si to reduce the overall thickness of the structure, while maintaining a low density of defects in III–V layers and hence the performance of the InAs/GaAs QD laser. A very high operating temperature of 130 °C has been demonstrated for an InAs/GaAs QD laser by this approach.

Direction and speed wind shear modify turbine performance by changing inflow conditions on turbine blades. Using observations from the 2013 CWEX campaign, we found the daily atmospheric boundary layer transitions (morning and evening) match periods of high electricity demand for a wind farm in central Iowa. Power production during these periods was undermined for large direction shear and low speed shear scenarios. The morning transition displayed larger direction shear over the rotor layer for most wind speeds compared to the evening period. This resulted in lower turbine performance for the morning compared to the evening and whole day. This study shows that the combined effect of direction and speed shear is affecting turbine operation during high electricity demand times of day, predominantly during the morning at this wind farm.

Plant-microbial fuel cells (PMFCs) are an interesting renewable energy technology that has the potential to generate clean electricity without competing with agriculture for land space. In this study, the electricity generation potential of mung beans (Vigna radiata) in a PMFC set-up with different electrode materials was explored. Three types of set-ups were prepared with five replicates each: PMFCs with stainless steel electrodes, PMFCs with graphite electrodes, and control pots without electrodes. This experimental set-up allowed for the evaluation of the better electrode material, and whether the PMFC environment harms or benefits the plants. The voltage gathered suggests that the potential difference generated in the PMFCs with differing types of electrodes were statistically the same (α = 0.05). The same can be said for power and power density, although the system with stainless steel electrodes generated more power towards the end of the experiment. It was also evident that PMFCs with stainless steel electrodes experienced prolonged time lags due to the reduced biocompatibility of stainless steel. Polarization studies showed that a single PMFC is capable of generating power densities of 0.35 mW/m2 and 0.12 mW/m2 for stainless steel and graphite systems, respectively. The increased power density of PMFCs with stainless steel indicate the lowering of internal resistance brought by the stainless steel. Plants in the PMFCs set-ups were seen to grow faster, taller, and have higher pod output than those in the control set-up. These results indicate that the PMFC technology can be implemented in agricultural land for the continuous generation of passive electricity while growing food crops, eliminating the competition between energy generation and agriculture.

The main goal of the present paper is to show how to form a constellation of small satellites when all small satellites leave from a larger spacecraft. It is assumed that they will all stay in a planar formation, in the same orbital plane of the mother spacecraft, just dispersed in terms of mean anomaly. Initially, it is considered that the larger satellite orbits the Earth in an almost circular orbit with 2000 km of altitude. Then, a search for initial conditions of the small satellite is performed to find the best ones to move it away from the larger satellite such that it is allocated in a co-orbital orbit with respect to the larger satellite. These initial conditions should minimize the consumption of an impulsive maneuver required to move away the small satellite from the large one to put it in course to its final orbit, trying to make the best use of the most relevant perturbations, such as the solar radiation pressure and the oblateness of the Earth. In a second study, we will analyze the influence of the solar radiation pressure, depending on the A/m ratio of the spacecraft, in the trajectories.

In the present work luminescence properties of terbium trivalent (Tb3+) doped ZrO2 were studied. Ultrasonic spray pyrolysis (USP) technique was employed to deposit the films. PL emission of the ZrO2:Tb3+ films exhibits emission peaks around 489, 548, 588, and 620 nm corresponding to transitions 5D4→7F6, 5D4→7F5, 5D4 →7F4, and 5D4→7D3 was seen when excited by excitation wavelength 288 nm. TL glow curves for ZrO2:Tb3+ exhibit a glow curve with a well-defined peak centered in around 170°C. TL signal as a function of dopant concentration showed a maximum at 10 at%. The best intensity of TL response as a function of UV radiation wavelength was in 230 nm. TL response fading and reusability were also analyzed. The ZrO2:Tb3+ films has been found to have simple and sharp glow peak which should be considered for dosimetric applications.

beta-Ga_2O_3 intergrowths have been revealed in the SnO_2 rutile structure when SnO_2/Ga_2O_3 complex nanostructures are grown by thermal evaporation with a catalyst-free basis method. The structure is formed by a Ga_2O_3 nanowire trunk, around which a rutile SnO_2 particle is formed with [001] aligned to the [010] Ga_2O_3 trunk axis. Inside the SnO_2 particle, beta-Ga_2O_3 units occur separated periodically by hexagonal tunnels in the (210) rutile plane. Orange (620 nm) optical emission from tin oxide, with a narrow linewidth indicating localised electronic states, may be associated with this beta-Ga_2O_3 intergrowth.

Ultraviolet (UV) irradiance measurements are usually associated with large inaccuracies and uncertainties complicating the comparability of corresponding measurement equipment and its data. For supervisors or safety experts, though, it is mandatory to measure reliable UV irradiances with regard to occupational safety regulations. The following work aims at an intercomparison of five different types of spectroradiometers regarding their wavelength alignment and irradiance accuracy in the UV spectral region that provides the reader with information on how to determine and compare the measurement accuracies of their own devices. In a first step, measurements of two UV irradiance standards, a deuterium and a halogen lamp, were carried out. The percentage deviations of the measured total UV irradiances from their calibrated ones are smaller than ±10% for all spectroradiometers. The quality of wavelength accuracy as well as of the spectral bandwidth, both investigated by means of a low pressure mercury argon lamp are consistent with those stated by the manufacturers. In a second step, UV radiation from a metal active gas welding arc was examined at three distances in combination with a variation of welding current and arc length to check the behaviour of UV irradiance accuracy in field. The overall averaged standard deviation of these field measurements for all CCD array detectors is given by ±8%. For high welding currents this accuracy decreases to ±21%.

An arrangement of plates was built using two minerals, calcite and hematite, deposited on glass (slides). The plates were placed in Chilapa de Alvarez city, in the southeast of Mexico. The goal of this work is to prove that mineral plates perform better than glass in nocturnal radiative cooling phenomena. The results obtained are that the glass/hematite plate collected 1.2–1.5 × 10−3 l of water and the glass/calcite plate only 0.71–0.75 × 10−3 l; meanwhile dew was not observed on a glass plate without minerals.

The availability of small solid-state lasers, efficient CCD detectors and compact optics has permitted the development of portable Raman spectrometers, which are of great interest for some applications, like cultural heritage or geochemistry. Some of them are 'home made' designs built by combining different elements that are commercially available. In the design phase of these instruments it is of great help to use computer tools, like ray-tracing, that permit the calculation of the spectrometer's performances, and the selection and optimization of the most suitable design. In this paper, we present a ray-tracing study of a laboratory dispersive Raman spectrometer performed with a freely available software package. We calculate the instrumental functions, resolving power, resolutions, aberrations, etc and benchmark some of the results with experimental values. We demonstrate the suitability of these codes for modelling Raman dispersive spectrometers, and their utility, not only in the design phase, but also during the operation of the spectrometer in order to check if it works close to the theoretical performance.

We demonstrate that the energy of a system of atoms can be uniquely evaluated using a series of structure independent, perfectly transferable many-body potentials. This allows one to compare empirical energy parametrizations on the basis of the behaviours of their potential expansions. It is shown how the representations of the energy using many-body potentials, which focuses on the positional degrees of freedom, and the conventional cluster expansion method, which focuses on the ordering degrees of freedom in a multicomponent lattice system, can be merged into a generalized cluster expansion.

X-ray reflectivity curves at 20 keV photon energy of alpha-quartz spherically curved crystals have been measured using a micrometric synchrotron beam at the ESRF BM5. Six thin quartz crystals samples with curvature radii of 150 and 250 mm have been studied. Experimental results are compared with diffraction profile calculations using a lamellar model and a good agreement is found.

In this work, we analysed the cavity length dependence of the internal, differential and power conversion efficiencies in AlGaAs/GaAs multiquantum well (MQW) lasers. We developed a theoretical model to calculate the threshold current and from it, the corresponding efficiencies. In this model we take into account a radiative process, and nonradiative mechanisms such as recombination from X and L valleys of the conduction band, Auger recombination, interface recombination and the carrier leakage over the heterostructure. Our modelling results for the threshold current are compared with the experimental data reported in the literature for different structures, showing a good agreement. We show that the internal and differential quantum efficiencies are greater in MQW lasers for all cavity lengths. In the case of the power conversion efficiency, it is higher only in MQW lasers than in their single quantum well counterparts for small values of cavity lengths.

InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silicon-based optoelectronics such as infrared photondetectors/emitters and highly sensitive phototransistors, as well as in the generation of renewable electricity. However, producing optically efficient InAsSb NWs with a high Sb content remains a challenge, and optical emission is limited to 4.0 μm due to the quality of the nanowires. Here, we report, for the first time, the success of high-quality and optically efficient InAsSb NWs enabling silicon-based optoelectronics operating in entirely mid-wavelength infrared. Pure zinc-blende InAsSb NWs were realized with efficient photoluminescence emission. We obtained room-temperature photoluminescence emission in InAs NWs and successfully extended the emission wavelength in InAsSb NWs to 5.1 μm. The realization of this optically efficient InAsSb NW material paves the way to realizing next-generation devices, combining advances in III-V semiconductors and silicon.

The effect of growth interruption time on the structural properties of InAs/GaAs self-assembled quantum dots grown by molecular beam epitaxy on (3 1 1)B GaAs substrates is studied. Changes both in the density and the size of the dots in comparison with a sample without growth interruption are presented. The trends of both parameters with the interruption time are closely related to red shift and increased photoluminescence intensity observed in the set of samples. Growth interruption allows larger dots; however there is a limit after which dots exceed a critical size and become defective.

The properties of a monochromatic x-ray backlighting system based on a spherically bent crystal were investigated. Simulations of spatial resolution for spherically bent crystals with different radius of curvature and for several wavelengths of incidence radiation were done using the ray-tracing method. Test experiments were carried out to demonstrate the high spatial resolution using the incoherent soft x-ray radiation produced by laser- and x-pinch plasmas. Both experimental and theoretical results show that a spatial resolution of at least 4 μm can be obtained in a field of view ranging from a few mm to cm. The narrow spectral band of the diffracted beam (Δλ/λ ~ 3 × 10−4), the high efficiency of the presented scheme and the possibility of significantly reducing the self radiation of the studied object make it one of the most promising backlighting systems. This scheme permits the essential reduction of requirements of the source of radiation and could be a less costly alternative to using x-ray lasers for such purposes.

This paper describes the design of a prototype telecare system, which allows to provide home care to patients with mild cognitive impairment and thus ensures their permanence in their usual environment. Telecare is oriented towards people who require constant attention due to conditions of advanced age, illness, physical risk or limited capabilities. Telecare offers these people a greater degree of independence. QFD methodology is used to develop electronic devices intended to monitor the environment and physiological state of the user continuously, providing communication between the telecare system and a monitoring center in order to take the most appropriate actions in any abnormal event.

The phase transitions occurring in the Ising square antiferromagnet with first- (J1) and second- (J2) nearest-neighbour interactions are studied using several mean-field approximations and for a wide range of R=J2/J1. The largest approximation used corresponds to a nine-point cluster approximation of the cluster variation method. In this case, the transition temperatures as a function of R are found to be in excellent agreement with those obtained by other methods. The mean-field approximations predict a first-order transition in the range 0.5

Local and average electronic and magnetic properties of transition metal alloys are strongly correlated to the distribution of atoms on the lattice sites. The ability of some systems to form long range ordered structures at low temperature allows to discuss their properties in term of well identified occupation operators as those related to long range order (LRO) parameters. We show that using theoretical determinations of these LRO parameters through statistical models like the cluster variation method (CVM) developed to simulate the experimental phase diagrams, we are able to reproduce a lot of physical properties. In this paper we focus on two points: (i) a comparison between CVM results and an experimental determination of the LRO parameter by NMR at 59Co in a CoPt3 compound, and (ii) the modelling of the resistivity of ferromagnetic and paramagnetic intermetallic compounds belonging to Co-Pt, Ni-Pt and Fe-Al systems. All experiments were performed on samples in identified thermodynamic states, implying that kinetic effects are thoroughly taken into account.

A four orders-of-magnitude reduction in high temperature leakage current was realized through the use of IrO2 top electrodes in thin film lead zirconate titanate capacitors which has been shown to directly impact the performance of future energy conversion applications. Pyroelectric energy conversion is enhanced near the material Curie temperature, but elevated leakage current in this temperature range hinders current applications. Conductivity experiments varying temperature, composition, and applied bias showed that oxygen vacancy hopping dominates the leakage current in the thin film capacitors above 200 °C. IrO2 top electrodes allow for a reduction in vacancy concentration by allowing for oxygen to be reintroduced during a post-processing annealing step for the thin film. The power lost to leakage current through the pyroelectric conversion cycle is explored. Improvements in remnant polarization and pyroelectric constant are also realized.

Type II emission optoelectronic devices using GaAsSb strain reduction layers (SRL) over InAs quantum dots (QDs) have aroused great interest. Recent studies have demonstrated an extraordinary increase in photoluminescence (PL) intensity maintaining type II emission after a rapid thermal anneal (RTA), but with an undesirable blueshift. In this work, we have characterized the effect of RTA on InAs/GaAs QDs embedded in a SRL of GaAsSb by transmission electron microscopy (TEM) and finite element simulations. We find that annealing alters both the distribution of Sb in the SRL as well as the exchange of cations (In and Ga) between the QDs and the SRL. First, annealing causes modifications in the capping layer, reducing its thickness but maintaining the maximum Sb content and improving its homogeneity. In addition, the formation of Sb-rich clusters with loop dislocations is noticed, which seems not to be an impediment for an increased PL intensity. Second, RTA produces flatter QDs with larger base diameter and induces a more homogeneous QD height distribution. The Sb is accumulated over the QDs and the RTA enlarges the Sb-rich region, but the Sb contents are very similar. This fact leaves the type II alignment without major changes. Atomic-scale strain analysis of the nanostructures reveal a strong intermixing of In/Ga between the QDs and the capping layer, which is the main responsible mechanism of the PL blueshift. The improvement of the crystalline quality of the capping layer together with higher homogeneity QD sizes could be the origin of the enhancement of the PL emission.

In this work the growth of complex n-type, high Ge content superlattice structures by reduced pressure chemical vapor deposition is presented. The structures feature 50 repeats of a 14 layer period, which includes a main quantum well that is between 13 and 21 nm wide. The total epitaxy thickness is approximately 8 μm. Diffusion and segregation in the structures was minimized by using a low growth temperature. Materials characterization shows the structures to be of good crystalline quality, with the thickness of all layers close to the design, abrupt interfaces, and uniformity throughout the structures. High angle annular dark field scanning transmission electron microscopy is shown to be an ideal technique for measuring layer thickness and interface quality in these structures.

There are many applications of the close approach maneuvers in astronautics, and several missions used this technique in the last decades. In the present work, those close approach maneuvers are revisited, but now considering that the spacecraft passes around an oblate planet. This fact changes the distribution of mass of the planet, increasing the mass in the region of the equator, so increasing the gravitational forces in the equatorial plane. Since the present study is limited to planar trajectories, there is an increase in the variation of energy given by the maneuver. The planet Jupiter is used as the body for the close approach, but the value of J2 is varied in a large range to simulate situations of other celestial bodies that have larger oblateness, but the same mass ratio. This is particularly true in recent discovered exoplanets, and this first study can help the study of the dynamics around those bodies.

X-ray imaging crystal spectrometers with high spectral and spatial resolution are currently being used on magnetically confined fusion devices to infer the time history profiles of ion and electron temperatures as well as plasma flow velocities. The absolute measurement of flow velocities is important for optimizing various discharge scenarios and evaluating the radial electric field in tokamak and stellarator plasmas. Recent studies indicate that the crystal temperature must be kept constant to within a fraction of a degree to avoid changes of the interplanar 2d-spacing by thermal expansion that cause changes in the Bragg angle, which could be misinterpreted as Doppler shifts. For the instrumental parameters of the x-ray crystal spectrometer on Alcator C-Mod, where those thermal effects were investigated, a change of the crystal temperature by 1 °C causes a change of the lattice spacing of the order of Δd = 1 × 10−5 A introducing a fictitious velocity drift of the order of ~3 km s−1. This effect must be considered for x-ray imaging crystals spectrometers installed on LHD, KSTAR, EAST, J-TEXT, NSTX and, in the future, W7-X and ITER.

The effects of rapid thermal annealing on the photoluminescence emission obtained from ten-layer stacks of GaSb/GaAs type-II single monolayer quantum dots and Stranski–Krastanow grown quantum rings have been studied and interpreted. Post-growth rapid thermal annealing was performed with proximity capping at temperatures from 550 °C to 800 °C, resulting in an increase in photoluminescence emission intensity and a blue shift in peak energy in both types of stacks, together with changes in the activation energy for thermal quenching. This behaviour originates from Sb–As intermixing and changes in morphology of the nanostructures formed using the two different growth mechanisms.

International audience; The thermal deformation of a liquid nitrogen cooled silicon crystal under increasing absorbed power undergoes five phases: i) no deformation at zero power, ii) concave shape of the crystal, iii) appearance of a central bump, iv) minimum of the slope error averaged over the beam footprint on the crystal due to the balance between the initial concave shape and the growing central bump, and v) rapid growth of the thermal bump. In general, a liquid nitrogen cooled silicon crystal is designed to operate before the appearance of phase v), and mostly in phase ii) ( concave shape). This concave shape of the crystal leads to a focusing effect on the beam, which should be considered in combination with other optical elements in the design and optimization of the beamline optical layout

We report on the epitaxial growth and photoluminescence (PL) of InAs0.926Sb0.063N0.011/InAs multi-quantum wells (QWs) grown using plasma-assisted molecular beam epitaxy. These dilute nitride QWs exhibit bright PL in the mid-infrared spectral range up to a temperature of 250 K without any post-growth annealing. Consideration of the power dependent PL behaviour is consistent with a type I band line-up in these QWs, arising from a strong lowering of the conduction band edge due to N-induced band anti-crossing effects.

In this paper we present the results of the synthesis of GaN in an AP-MOVPE system heated by infrared lamps starting from gallium nitride films obtained by nitridation of gallium arsenide. Although dependence of the characteristics of the different parameters of the deposition process on the properties of the layers has been widely studied, the influence of the nature and design of the heating source has been only scarcely reported. We show that the ratio between the two phases depends on the characteristics of the heating source, as well as on other growth parameters. Our results show a compromise between the characteristics of the photoluminescence spectra, the surface morphology and the cubic phase to hexagonal phase ratio. The growth conditions can be adjusted for optimal performance.

The MINOS experiment has the potential to observe electron neutrino appearance for a set of oscillation parameters that has not been excluded by the CHOOZ experiment. However, the observation of this hypothetical signal relies on an accurate understanding of the backgrounds. In order to understand the backgrounds, an analysis of the MINOS near detector energy spectrum, which contains no oscillated signal, is utilized. The results of this analysis can then be extrapolated to the far detector to yield the background estimate. The details of the signal versus background separation methods and the results of this near detector analysis are discussed.

At the Kernfysisch Versneller Instituut (KVI) in Groningen, NL, a new facility (TRIµP) is under development. Radioactive nuclei will be produced using heavy ion beams from the superconducting AGOR cyclotron. They are then slowed down and finally trapped in ion or atomic traps in order to perform precision experiments with them. The facility will be open for use by the worldwide community. The present local research programme includes precision studies of nuclear β-decays through β-neutrino (recoil nucleus) momentum correlations in weak decays as well as searches for permanent electric dipole moments in heavy atomic systems. Such experiments offer a large potential for discovering new physics or to put sensitive limits on parameters in models beyond standard theory.

The interplay between magnetic properties and chemical ordering in the Co1-xPtx system is investigated theoretically and experimentally. Experimental results for the Curie temperature, magnetisation and paramagnetic susceptibility in ordered and disordered states are discussed within the framework of statistical models. The authors show that the magnetic moments on Pt atoms depend sensitively on the local chemical environment. A complete equilibrium phase diagram is also calculated and compared with the experimental data.

A short-range order dependent electronically self-consistent theory of ordering in ferromagnetic substitutional binary alloys is presented. The alloy internal energy is calculated using the cluster-Bathe-lattice method. The calculations use the results of elemental electronic structure calculations and experimental magnetic moments as input. The configuration dependence of the enthalpy of formation is used to determine the zero-temperature stable phases. Using this method it is found that ferromagnetism induces the A2 to B2 chemical ordering transition in the cobalt-iron system.

The authors study in the JWKB approximation the energy levels of the symmetric anharmonic oscillators V(x)=Ax2+Bx4 for different signs and values of A and B. Comparisons are made with published results for specific cases and with numerical calculations. They given an additional example of exact value, to add to the very rare catalogue of known examples.