Neurodegenerative and neuroinflammatory diseases regularly cause optic nerve and retinal damage. Evaluating retinal changes using optical coherence tomography (OCT) in diseases like multiple sclerosis has thus become increasingly relevant. However, intraretinal segmentation, a necessary step for interpreting retinal changes in the context of these diseases, is not standardized and often requires manual correction. Here we present a semi-automatic intraretinal layer segmentation pipeline and establish normative values for retinal layer thicknesses at the macula, including dependencies on age, sex, and refractive error. Spectral domain OCT macular 3D volume scans were obtained from healthy participants using a Heidelberg Engineering Spectralis OCT. A semi-automated segmentation tool (SAMIRIX) based on an interchangeable third-party segmentation algorithm was developed and employed for segmentation, correction, and thickness computation of intraretinal layers. Normative data is reported from a 6 mm Early Treatment Diabetic Retinopathy Study (ETDRS) circle around the fovea. An interactive toolbox for the normative database allows surveying for additional normative data. We cross-sectionally evaluated data from 218 healthy volunteers (144 females/74 males, age 36.5 ± 12.3 years, range 18–69 years). Average macular thickness (MT) was 313.70 ± 12.02 μm, macular retinal nerve fiber layer thickness (mRNFL) 39.53 ± 3.57 μm, ganglion cell and inner plexiform layer thickness (GCIPL) 70.81 ± 4.87 μm, and inner nuclear layer thickness (INL) 35.93 ± 2.34 μm. All retinal layer thicknesses decreased with age. MT and GCIPL were associated with sex, with males showing higher thicknesses. Layer thicknesses were also positively associated with each other. Repeated-measurement reliability for the manual correction of automatic intraretinal segmentation results was excellent, with an intra-class correlation coefficient >0.99 for all layers. The SAMIRIX toolbox can simplify intraretinal segmentation in research applications, and the normative data application may serve as an expandable reference for studies, in which normative data cannot be otherwise obtained.

From magnetotransport measurements it is generally believed that Hg-VI compounds show zero gap semiconducting behavior. Applying combined angle-resolved photoemission and inverse photoemission spectroscopy on HgSe(001) c͑2 3 2͒, we observe a positive fundamental gap of about 0.42 eV and a surface related state close to the Fermi level above the conduction band minimum. Following the results of this direct determination of the k-resolved band structure, previous experiments favoring zero gap models of Hg-VI compounds need to be reinterpreted. [S0031-9007 (97)03026-3] PACS numbers: 73.20.At, 79.60.BmBecause of its technological interest for electro-optical devices, the Zn and Cd containing II-VI compound semiconductors have been studied intensively over the past decade. The group of Hg containing II-VI compounds, however, has been scarcely investigated since its electronic structures were reported to reveal zero or even negative fundamental gaps with inverted band structures. Following results on a-Sn from Groves and Paul [1], the valence band maximum (VBM) was considered to be degenerate with the conduction band minimum (CBM) revealing G 8 symmetry. Early magnetotransport measurements measuring extremal cross sections of Fermi surfaces indeed found evidence for an inverted band structure in bulk HgSe [2-4] similar to those observed on HgTe [5] and b-HgS [6].Semiempirical band structure calculations for HgSe [7-9] and HgTe [7,8,10] fitting those data, consequently, show an inverted band structure with valence band widths of the order of 3.3-4.4 eV for HgSe and 3.6-4.8 eV for HgTe, respectively. Photoemission results on HgSe and HgTe [11][12][13][14][15], in contrast, exhibit larger valence band widths of about 5.0-5.8 eV. The experimental position of the Fermi level with respect to the VBM is of particular interest in order to distinguish between metallic and semiconducting band structures. It has, however, only been reported for HgTe(110) by Yu et al. [11]. They determined the Fermi level to be 0.59 eV above the VBM. Infrared absorption data [16,17] show two absorption edges around 0.4 and 0.2 eV photon energy which are interpreted as transitions from the two upper valence bands near G 8 and G 6 into the G 8 conduction band, leading to a fundamental energy gap of approximately 20.2 eV.The experimental results, together with the semiempirical band structure calculations reported so far, do not give a consistent picture of the band structure around the Fermi level of Mercury containing II-VI compounds. This can be attributed to the type of experiments giving only indirect information on band structures (optical and magnetotransport measurements) and theories fitting these data.In this Letter we take HgSe as the prototype material of Hg-VI compounds which, in addition, may be compared to the better-known narrow gap semiconductor InAs having a similar lattice constant. We report on direct measurements of the k-resolved occupied and unoccupied band structure around the Fermi level of HgSe(001) c͑2 3 2͒ by means of comb...

Angle-resolved ultraviolet photoemission spectra are interpreted by combining the energetics and spatial properties of the contributing states. One-step calculations are in excellent agreement with new azimuthal experimental data for GaAs(110). Strong variations caused by the dispersion of the surface bands permit an accurate mapping of the electronic structure. The delocalization of the valence states is discussed analogous to photoelectron diffraction. The spatial origin of the electrons is determined, and found to be strongly energy dependent, with uv excitation probing the bonding region.PACS numbers: 79.60.-i, 61.14. Dc, 73.20.At Angle-resolved ultraviolet photoemission spectroscopy (ARUPS) is probably the most powerful single experimental technique for studying the valence electronic structure of solids. However, until recently, ARUPS has been primarily limited to investigating the positions in energy of valence bands along a few high-symmetry directions in reciprocal space. That is, the intensity of the photoemission peaks was usually not analyzed quantitatively, and most of the information in the full hemisphere above the surface was lost. One reason for this limitation in ARUPS studies is the lack of any simple rules for explaining such valence spectra beyond those that have been found useful for mapping bands in energy. The most often applied model in ARUPS is that of direct (wave-vector-conserving) transitions between bulk bands [1], with the final state often being simplified to a plane wave [2]. Beyond this, free-electron final states with atomic-like optical transitions [3] and final-state scattering of electrons emerging from a localized core orbital [4] have been used to better understand the resulting angular distributions in photoemission. The interest in such angular distributions of intensity has recently been stimulated by the measurement of full-hemisphere intensity maps in ARUPS [5][6][7][8][9][10], with the data being analyzed so far using plane-wave final states [6], single scattering [7], bulk bands [8], and atomic-like transitions [9], as well as the one-step model [11,12]. The most accurate description of valence ARUPS involves calculations within this one-step model and includes the precise optical matrix elements, full multiple scattering, the explicit presence of the surface potential, and the resulting more complex initial and final states. However, there has to date been no systematic treatment of the angular distribution of intensity within such a model.In this Letter, we quantitatively investigate the influence of the initial state and its charge distribution on the angular distribution of intensity in ARUPS, using the one-step model. We demonstrate that the combined consideration of both energy positions and intensity patterns will be necessary for the most useful interpretation of angle-scanning data, and point out the additional information that can be derived in this way. For our calculations and measurements, azimuthal scans are chosen, which allow a high accuracy in th...