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- DeVita, Michael A., et al.
(författare)
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"Identifying the hospitalised patient in crisis"-A consensus conference on the afferent limb of Rapid Response Systems
- 2010
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Ingår i: Resuscitation. - : Elsevier BV. - 1873-1570 .- 0300-9572. ; 81:4, s. 375-382
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Tidskriftsartikel (refereegranskat)abstract
- Background: Most reports of Rapid Response Systems (RRS) focus on the efferent, response component of the system, although evidence suggests that improved vital sign monitoring and recognition of a clinical crisis may have outcome benefits. There is no consensus regarding how best to detect patient deterioration or a clear description of what constitutes patient monitoring. Methods: A consensus conference of international experts in safety, RRS, healthcare technology, education, and risk prediction was convened to review current knowledge and opinion on clinical monitoring. Using established consensus procedures, four topic areas were addressed: (1) To what extent do physiologic abnormalities predict risk for patient deterioration? (2) Do workload changes and their potential stresses on the healthcare environment increase patient risk in a predictable manner? (3) What are the characteristics of an "ideal" monitoring system, and to what extent does currently available technology meet this need? and (4) How can monitoring be categorized to facilitate comparing systems? The major findings include: (1) vital sign aberrations predict risk, (2) monitoring patients more effectively may improve outcome, although some risk is random, (3) the workload implications of monitoring on the clinical workforce have not been explored, but are amenable to study and should be investigated, (4) the characteristics of an ideal monitoring system are identifiable, and it is possible to categorize monitoring modalities. It may also be possible to describe monitoring levels, and a system is proposed. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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| 2. |
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| 3. |
- Darakchieva, Vanya, 1971-, et al.
(författare)
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Anisotropic strain and phonon deformation potentials in GaN
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:19, s. 195217-
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Tidskriftsartikel (refereegranskat)abstract
- We report optical phonon frequency studies in anisotropically strained c -plane- and a -plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E1 (TO), E1 (LO), and E2 phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c E1 (TO), c E1 (LO), and c E2 are determined. A distinct correlation between anisotropic strain and the A1 (TO) and E1 (LO) frequencies of a -plane GaN films reveals the a A1 (TO), b A1 (TO), a E1 (LO), and b E1 (LO) phonon deformation potentials. The a A1 (TO) and b A1 (TO) are found to be in very good agreement with previous results from Raman experiments. Our a A1 (TO) and a E1 (LO) phonon deformation potentials agree well with recently reported theoretical estimations, while b A1 (TO) and b E1 (LO) are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented. © 2007 The American Physical Society.
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| 4. |
- Darakchieva, Vanya, et al.
(författare)
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Effect of anisotropic strain on phonons in a-plane and c-plane GaN layers
- 2007
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 300:1, s. 233-238
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Tidskriftsartikel (refereegranskat)abstract
- We have studied phonons in two types of anisotropically strained GaN films: c-plane GaN films grown on a-plane sapphire and a-plane GaN films grown on r-plane sapphire. The anisotropic strain in the films is determined by high-resolution X-ray diffraction (HRXRD) in different measuring geometries and the phonon parameters have been assessed by generalized infrared spectroscopic ellipsometry (GIRSE). The effect of strain anisotropy on GaN phonon frequencies is presented and the phonon deformation potentials aA1 (TO), bA1 (TO), cE1 (TO) and cE1 (LO) are determined. © 2006 Elsevier B.V. All rights reserved.
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| 5. |
- Paskov, Plamen, 1959-, et al.
(författare)
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Optical properties of nonpolar a-plane GaN layers
- 2006
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Ingår i: Superlattices and Microstructures. - : Elsevier BV. - 0749-6036 .- 1096-3677. ; 40:4-6 SPEC. ISS., s. 253-261
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Tidskriftsartikel (refereegranskat)abstract
- We have studied optical properties of nonpolar a-plane GaN layers grown on r-plane sapphire by metalorganic chemical vapor deposition and hydride vapor phase epitaxy using different nucleation schemes. Several emission bands, which are not typical for c-plane GaN, are observed in the photoluminescence spectra and their excitation-intensity, temperature, and polarization dependencies are examined. In addition, the spatial distribution of the emissions was examined by cathodoluminescence imaging and relations of the different emissions with particular structural features in the layers are revealed. The results are discussed with emphasis on the origin of the emission line and particular recombination mechanisms. © 2006 Elsevier Ltd. All rights reserved.
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| 7. |
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| 8. |
- Roder, C., et al.
(författare)
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Strain in a-plane GaN layers grown on r-plane sapphire substrates
- 2006
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Ingår i: Physica Status Solidi (A) Applications and Materials. - : Wiley. - 1862-6300. ; 203:7, s. 1672-1675
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Tidskriftsartikel (refereegranskat)abstract
- The strain in a-plane GaN layers of different thickness grown on r-plane sapphire substrates by hydride vapor phase epitaxy was studied by X-ray diffraction. The layers are found to be under compression in the growth plane and under tension in the growth direction. Therefore, the symmetry of the GaN unit cell is no longer hexagonal but orthorhombic. With increasing layer thickness the strain relaxes and the curvature of the wafer increases. Wafer bending is proposed to be the major strain relaxation mechanism. The anisotropic in-plane strain relaxation is attributed to the elastic and thermal anisotropy of GaN and sapphire. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.
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| 9. |
- Roder, C., et al.
(författare)
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Stress and wafer bending of a -plane GaN layers on r -plane sapphire substrates
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100:10
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Tidskriftsartikel (refereegranskat)abstract
- The stress and wafer bending of (11 2- 0) a -plane GaN layers of different thicknesses grown on (1 1- 02) r -plane sapphire substrates by hydride vapor phase epitaxy were studied by high-resolution x-ray diffraction and photoluminescence and photoreflectance spectroscopies. The layers are found to be under compression in the growth plane and under tension in the growth direction. The elastic and thermal anisotropies of the GaN and the sapphire crystal result in an in-plane stress and a wafer curvature, both of which are different in the two in-plane directions parallel and perpendicular to the GaN c axis. The GaN unit cell is no longer hexagonal but orthorhombic. The stress relaxes with increasing GaN layer thickness while the curvature of the wafer increases. Different stress relief mechanisms are considered, and the stresses in the layer and the curvature of the wafer are calculated using standard models on wafer bending. The results suggest that the wafer bending is the dominant stress relief mechanism. In addition, the redshift of the near-band-edge photoluminescence and the free exciton photoreflectance peaks with increasing layer thickness is correlated with the strain data determined by x-ray diffraction. © 2006 American Institute of Physics.
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