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There is paucity in the level of knowledge on the actual insurer expenses associated with patients suffering with dementia in the developing world. Less is known about direct costs by severity and how costs vary because of the presence of other comorbidities.
Using claims data from an insurer for three years, we identified patients with AD with an algorithm that takes advantage of information on age, primary diagnosis, and services and drugs provided.
Distribution by dementia stage was as follows: mild 21%, moderate 53%, severe 17%, and undetermined 9%. Expenses paid for all causes by the insurer were at least double than estimated in the literature and were increasing annually at rates higher than 30%. Also, 92% of patients have at least another chronic condition.
Worldwide costs of dementia estimates maybe underestimating the actual costs to health systems in the developing world.
We investigated MOVPE growth conditions for AlInN layers with high growth rates and obtained 0.5µm/h with smooth surfaces. We found that short gas mixing time, relatively high growth temperature, and very low In/Al supply ratio were key growth parameters in order to obtain the AlInN layers with high growth rate and smooth surface simultaneously. AlInN/GaN DBRs grown under such growth conditions showed smooth surfaces and a reflectivity of over 99%.
We have investigated an influence of positive polarization charges generated at an interface between GaN barrier/p-AlGaN EB (Electron Blocking) layer in a blue-LED. Simulation results suggested that such polarization charges caused an electron overflow from QWs. The simulation results also indicated that sufficient acceptor doping at the interface could neutralize the positive polarization charges and suppress the electron overflow. We then demonstrated the electron overflow caused by the positive polarization charges and its suppression with sufficient Mg doping at the interface by monitoring emissions from an additional second QW inserted between the p-EB layer and the p-GaN layer. Finally we conclude that the contribution of the electron overflow is not significant for the efficiency droop in blue-LEDs.
Intermolecular interaction potentials of the acrylamide dimer in 12 equilibrium configurations have been calculated using the second-order Møller-Plesset (MP2) perturbation theory. We have employed Pople’s medium size basis sets [up to 6-311++G(3df,2p)] and Dunning’s correlation consistent basis sets (up to aug-cc-pVTZ). We have also carried out density functional theory (DFT) type calculations and compared the results with those calculated with the MP2 theory.
We analyze photoluminescence (PL) and electroluminescence (EL) using a hyperspectral imager that records spectrally resolved luminescence images of solar cell absorbers. The system is calibrated to yield the luminescence flux in absolute values. This system enables to quantitatively image physical parameters such as the photovoltage with an uncertainty of less than 30mV. The wide field illumination, low power excitation and fast acquisition brings new insights compare to classical setups such as confocal microscope. Several types of absorbers have been analyzed. For instance, we can investigate spatial fluctuations of the Quasi Fermi Levels splitting in CIGS polycristalline absorbers and link those fluctuations to transport properties. The method is general to the point that third generation PV cells absorbers can also be evaluated. We illustrate the great potential of our setup by imaging quasi Fermi levels splitting in Intermediate Band Solar cells. Such techniques, directly evaluating the performance of photovoltaic absorbers and devices are needed for fast, high throughput investigations of combinatorial experiments such as the projects carried out for the material genomics programme.
The solar absorptance αs of nanostructured selective surface (NSS) for solar thermal energy is improved. The NSS are prepared by AC electrochemical impregnation of metal inclusions (MI) into porous anodized aluminum oxide (AAO). The dependence of the NSS performance with composition depth profile and MI is studied by numeric simulations based in a gradient index model and effective medium theory. The results are compared with experimental NSS prepared varying three control parameters and MI (Ni, Cu, Ag). The αs is improved to > 85% (keeping thermal emittance εT relatively low) for Ni MI, mainly by increasing MI content. Increasing AAO thickness or MI molecular weight (for a given experimental composition profile) also improves the performance. For Ag the αs was further improved to 90%.
Continuous fiber reinforced composites (RFC) are hierarchal and complex at multiple scales. In this work, tools are developed to automate the 3D characterization and quantification of the overall microstructure. Structure quantification enables accurate representation for material simulation and property prediction for the integrated computation materials engineering (ICME) of RFC based components. Relationships are developed to describe the key attributes of the microstructure at multiple scales including the individual fibers, tows, weave, porosity, and secondary matrix phases, which are treated as 'gestalts' of the structure. Here gestalt refers to the essence of shape or complete form of key features of the microstructure such as those of the tow architecture of the textile. Visualization tools are developed based on an artificial color scheme that allow the visual recognition of whole tows instead of just the collection of simple lines and curves representative of the fibers, which provides means whereby the gestalt of the microstructure can be visualized at the tow scale. These tools are demonstrated using a 3D dataset of the SiNC/SiC S200 ceramic matrix composite material (CMC) obtained via automated serial sectioning. Methods are then demonstrated to generate microstructure models representative of the characterized material for finite element analyses (FEA).
The accumulation of boron within the porous nickel ferrite (NiFe2O4, NFO) deposits on nuclear fuel rods is a major technological problem with important safety and economical implications. In this work, first-principles results are combined with experimental thermochemical data to analyze the energetics of vacancy formation in NFO and the possibility of B incorporation into the structure of NFO. Under solid-solid equilibrium conditions, the calculations suggest that vacancy formation and B incorporation into the NFO structure is energetically unfavorable, the main limiting factors being the narrow stability domain of NFO and the precipitation of B2O3, Fe3BO5, and Ni3B2O6 as secondary phases. Assuming solid-liquid equilibrium between NFO and the surrounding aqueous solution saturated with respect to NFO, the calculations predict that in operating PWR environment, Ni vacancies are likely to form. Under these conditions the possibility of B incorporation at the Ni vacancy sites cannot be excluded.
In organometallic vapor phase epitaxial growth of group III nitrides on sapphire, insertion of a low temperature interlayer is found to improve crystalline quality of AlxGa1−xN layer with x from 0 to 1. Here the effects of the low temperature deposited GaN or AlN interlayers on the structural quality of group III nitrides is discussed.
Identification of the electronic band structure in AlInGaN heterostructures is the key issue in high performance light emitter and switching devices. In device-typical GaInN/GaN multiple quantum well samples in a large set of variable composition a clear correspondence of transitions in photo- and electroreflection, as well as photoluminescence is found. The effective band offset across the GaN/GaInN/GaN piezoelectric heterointerface is identified and electric fields from 0.23 - 0.90 MV/cm are directly derived. In the bias voltage dependence a level splitting within the well is observed accompanied by the quantum confined Stark effect. We furthermore find direct correspondence of luminescence bands with reflectance features. This indicates the dominating role of piezoelectric fields in the bandstructure of such typical strained layers.
Uniaxial wurtzite group-III nitride heterostructures are subject to large polarization effects with significant consequences for device physics in optoelectronic and transport device applications. A central aspect for the proper implementation is the experimental quantification of polarization charges and associated fields. In modulated reflection spectroscopy of thin films and heterostructures of AlGaInN we observe pronounced Franz-Keldysh oscillations that allow direct and accurate readings of the field strength induced by polarization dipoles at the heterointerfaces. In piezoelectric GaInN/GaN quantum wells this dipole is found to induce an asymmetry in barrier heights with a respective splitting of interband transitions. This splitting energy appears to reflect in the transitions of spontaneous and stimulated luminescence in the well. From these experiments the polarization dipole is identified as controllable type-II staggered band offset between adjacent barrier layers which can extend the flexibility in AlGaInN bandstructure design. The derived field values can serve as important input parameters in the further interpretation of the entire system.
In the field of group-III nitrides, hetero-epitaxial growth has been one of the most important key technologies. A thick layer of AlGaN alloy with higher AlN molar fraction is difficult to grow on sapphire substrate, because the alloy layer is easily cracked. It is thought that one cause of generating cracks is a large lattice mismatch between an AlGaN and a GaN, when AlGaN is grown on the underlying GaN layer. We have achieved crack-free Al0.07Ga0.93N layer with the thickness of more than 1μm using underlying Al0.05Ga0.95N layer. The underlying Al0.05Ga0.95N layer was grown directly on sapphire by using the low-temperature-deposited buffer layer (LT-buffer layer). Since a lattice mismatch between the underlying Al0.05Ga0.95N layer and upper Al0.07Ga0.93N layer is relatively small, the generation of cracks is thought to be suppressed. This technology is applied to a GaN-based laser diode structure, in which thick n-Al0.07Ga0.93N cladding layer grown on the Al0.05Ga0.95N layer, improves optical confinement and single-robe far field pattern in vertical direction.
A study of the optoelectronic properties of strained 40 nm Ga1−xInxN layers on GaN films is presented. The fact of pseudomorphic strain leads to a new interpretation of the film composition when derived from x-ray scattering. In addition we directly confirm that strain induces huge piezoelectric fields in this uniaxial system by the observation of Franz-Keldysh oscillations in photoreflection. As a function of composition (0 < x < 0.2) and strain we derive the electronic band gap energy and the piezoelectric field strength. We interpret both in terms of effective bowing parameters and piezoelectric coefficients, respectively. From a spatially resolved micro photoluminescence at room temperature we find no evidence for spatial band gap or composition variations of more than 60 meV over the length scale from 1 to 50 μm (x=0.187) in our material. At the same time, an observed discrepancy between photoluminescence peak energy and photoreflection band gap energy increases with x to some 160 meV. We attribute this redshift to photon assisted tunneling in the huge piezoelectric fields (Franz-Keldysh effect).
In this work we study the influence of supercell scaling on magnetic properties in Ni-Mn-X-Z alloys by means of ab initio calculations with the help of Quantum Espresso PWSCF package and the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) code based on DFT approximation. It is shown that the supercell calculations for the equilibrium lattice parameter are coincided with the calculations for simple primitive lattice. The exchange parameters for Ni-Mn-X alloys obtained from supercell calculations are large than calculated for simple primitive lattice.
The transformation plateau on the strain-stress curve is the characteristic of superelasticity of bulk shape memory alloys upon tension/compression loading. However, recent studies show that such transformation plateau is hard to see when the sample size of shape memory alloys decreases to submicrons. In order to see what happened in such small scale samples during loading, in-situ compression test has been done with single crystal Cu-14.2Al-4.0Ni (wt %) submicron pillars. Our in-situ observation during compression demonstrates that the stress-induced martensitic transformation indeed occurs in submicron pillars, but is not suppressed. Furthermore, the transformation proceeds in a sequential nucleation-growth-nucleation dominated mode, but not the transient way like that in bulk materials. As a result, the stress keeps increasing throughout the transformation and no obvious transformation plateau can be detected. However, the underlying reason for such contrast transformation behaviors between our submicron pillars and bulk materials still needs further investigation.
In this work, we analyze the requirement to (Ba,Ca)(Zr,Ti)O3 thin films for applications in electrocaloric devices. We demonstrate that large temperature changes are realized mostly independent of the used material by applying sufficient electric fields. Ferroelectrics exhibiting a diffuse phase transition are beneficial for electrocaloric applications, but they change the range of operational temperatures.
Photonics Integrated Circuits (PICs) are being applied by the telecommunications industry as transceivers for fibre optic networks. The core component of a typical PIC is the laser array and these devices can have relatively low operating temperatures (15°C - 25°C) with a tight operating range (±0.1K). To accommodate such a specification, a thermal control system is required that can change the cooling rate through feedback. The power density of next generation PICs is at such a level to demand novel thermal management architectures including developments such as near source liquid cooling. In order to control the thermal performance of fluidic devices, effective methods for varying the rate of coolant are an essential component. Consequently, micro-valve structures are required, ideally involving passive actuation to meet stringent reliability standards. One solution to this challenge is to exploit the phase-change driven shape memory effect of the NiTi Shape Memory Alloy (SMA). A micro-valve could be developed from the NiTi SMA, thermally coupled to the laser array component in order to work passively to regulate the flow of coolant in a micro-channel. Such a valve would have to be intrinsically reliable, and the goal of this paper is to investigate the conditions that will affect this reliability. The objective of the work is to investigate the mechanical properties relevant to the design of a passive NiTi SMA micro-valve, with a focus on the formation of stress-induced Martensite bands. It is not understood why these bands form on a plane inclined at ∼55° to the axis of loading and in this paper theory is presented that suggests a reasoning for this. A plate sample of NiTi was tested in uni-axial tension and Digital Image Correlation (DIC) used to analyse the strain fields across the surface of the sample. The DIC results revealed areas of high stress concentrations occurring in bands inclined on average 53.86° to the axis of loading. The theory and experimental observations are in agreement with the literature but to validate the theory the crystal texture needs to be analysed in the stress concentration regions. This paper provides valuable insight into the mechanical behaviour of a passive NiTi SMA micro-valve subjected to a sufficient pressure to form stress-induced Martensite.
Structural and magnetic properties of Ni2-xPtxMnGa alloys are investigated from first principles calculations with the help of the spin-polarized relativistic Korringa-Kohn-Rostoker and Plane-Wave Self-Consistent Field methods. The atomic chemical disorder at specific site has been implemented using coherent potential approximation. Calculated equilibrium lattice parameters are in a good agreement with experimental data and other theoretical calculations. The composition dependences of the magnetic exchange couplings and the Curie temperature for cubic phase are obtained. Our calculations have shown that an increase content of Pt results to decrease of magnetic interactions between Mn atoms and to change of interaction sign from ferromagnetic type to antiferromagnetic one for composition Ni1.0Pt1.0MnGa. Calculated Curie temperatures are in an agreement with experimental data.
Density functional theory (DFT) based on the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) method is used to investigate the magnetic properties of nonstoichiometric Fe2+xMn1-xAl Heusler alloys, where 0 ≤ x ≤ 0.9. The composition dependences of the magnetic exchange couplings and the Curie temperature for the cubic L21 phase are obtained. Our simulations have shown that the Fe-Fe nearest neighbors present a strong ferromagnetic coupling. Moreover, these exchange interactions are larger than other interactions. The substitution of Mn by Fe in Fe2+xMn1-xAl (0 ≤ x ≤ 0.9) leads to an increase in the Curie temperature. This tendency and the values of Curie temperatures are in agreement with the experimental results for Fe2+xMn1-xAl (x = 0, and 0.1). The highest Curie temperature was observed for the Fe-richer alloy.