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Quantum wells of GaAs lattice matched to GaP have been studied by photoluminescence and electroreflectance. The quantum well thickness was varied between 1 and 6 monolayers in steps of 1 monolayer. Electron-hole transitions have been observed involving states both in the X band and in the Γ band, which have been modeled using a k.p. model in conjunction with the envelope function approximation. Overall agreement between theory and experiment is found using an unstrained valence band offset of 0.6 eV.

Bertolotti’s syndrome refers to the presence of pain associated to the anatomical variant of sacralization of the last lumbar vertebra. It is often a factor that is not addressed in the evaluation and treatment of lower back pain. The presence of a lumbosacral transitional vertebra is a common finding among general population with a prevalence that ranges between 4 and 30%, however, this finding is rarely associated to the cause of lower back pain and thus, the prevalence of Bertolotti’s syndrome in general population is unknown doe to underdiagnosis. The sacralization of the fifth lumbar vertebra has been related to changes in the anatomy and biomechanics of the spine with no general agreement to its clinical significance, however Bertolotti’s syndrome should be considered as a differential diagnosis for lower back pain, therefore, its pathophysiology, epidemiology and treatment must be a topic of general knowledge to physicians that often treat this condition.

The Raman Laser Spectrometer (RLS) is one of the three Pasteur Payload instruments located within the rover analytical laboratory drawer (ALD), for ESA's Aurora exploration programme, ExoMars 2020 mission. The instrument will analyse the crushed surface and subsurface samples that are positioned below the Raman optical head by the ALD carousel. The RLS engineering and qualification model (EQM) was delivered to ESA at the end of 2017, after a wide technical and scientific test characterization campaign. The scientific campaign comprised instrument calibration and detailed evaluation of the scientific requirements and overall performance. For spectral calibration, continuous emission standard lamps (such as Hg‐Ar, Ne, and Xe) were utilized, as well as Raman spectra of pure liquids typically used as standards (cyclohexane and carbon tetrachloride (CCl4)). In addition, Raman spectra of the RLS calibration target (CT), a small disc of polyethylene terephthalate (PET) were obtained at various temperatures. This target, placed inside the rover, will be used for both Instrument health checks and calibration activities throughout Mars operations. For the scientific requirements and performance evaluations, several liquid and solid samples were analysed under a wide range of ambient conditions. The obtained spectral band parameters (peak position, relative peak intensity, peak width, and peak profile) were evaluated. Also, the instrument response (in terms of SNR) was characterized at different integration times and detector operating temperatures. In this paper, we provide a description of the development, verification, functional test, and overall scientific performance of the RLS instrument developed for ExoMars. Particular attention is placed on the performance of the EQM, which is the most representative instrument, in terms of engineering and functionality, of the flight model (FM) and in addition is used for performing all the mechanical, thermal, and radiation tests necessary for space qualification (for planetary applications). The data presented and analysed here, comprise part of the overall dataset obtained during the full instrument characterization campaign conducted at INTA before and during delivery and integration of the EQM in the rover ALD at TAS‐I facilities (Torino, Italy). The results obtained confirm that the full functionality and scientific performance of the RLS instrument was maintained after integration.