Optically Stimulated Luminescence (OSL) signals from quartz can be used to determine the timing of deposition of sedimentary archives. OSL dating uses the accumulation of energy stored in a crystal structure to measure time. This stored energy is absorbed from ionising radiation, and is released (reset) by heat or daylight. The total energy (dose) absorbed since last resetting is measured using OSL, and divided by the rate of storage (dose rate) to give the time elapsed from the last heating or daylight exposure. In this Primer, we introduce the quartz OSL method and outline the signal resetting processes.We describe the origins and quantification of the dose rate and describe the daylight-sensitive OSL signal most appropriate to dose estimation. The most widely used dose measurement method is then introduced, together with quality-control procedures. A broad set of geological and archaeological studies are used to illustrate the wide range of potential applications, and we describe the challenges arising from different deposition environments and summarize evidence for the precision and accuracy of published ages. Uncertainties and minimum reporting are discussed together with methodological limitations, particularly when applied to young and old sediments. Finally, we highlight the anticipated future developments in the field.

Fluvial planation surfaces, such as straths, commonly serve as recorders of climatic and tectonic changes and are formed by the lateral erosion of rivers, a process that remains poorly understood. Here we present a study of kilometer‐wide, fluvially eroded, low‐relief surfaces on rapidly uplifting folds in the foreland of the southwestern Tian Shan. A combination of field work, digital elevation model analysis, and dating of fluvial deposits reveals that despite an arid climate and rapid average rock‐uplift rates of 1–3 mm/yr, rivers cut extensive (>1–2 km wide) surfaces with typical height variations of <6 m over periods of >2–6 kyr. The extent of this “beveling” varies in space and time, such that different beveling episodes affect individual structures. Between times of planation, beveled surfaces are abandoned, incised, and deformed across the folds. In a challenge to models that link strath cutting and abandonment primarily to changes in river incision rates, we demonstrate that lateral erosion rates of antecedent streams crossing the folds have to vary by more than 1 order of magnitude to explain the creation of beveled platforms in the past and their incision at the present day. These variations do not appear to covary with climate variability and might be caused by relatively small (much less than an order of magnitude) changes in sediment or water fluxes. It remains uncertain in which settings variations in lateral bedrock erosion rates predominate over changes in vertical erosion rates. Therefore, when studying fluvial planation and strath terraces, variability of both lateral and vertical erosion rates should be considered.

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Objective: This study aims to compare the increase in refractive error and axial length, variation of endothelium cells, and ratio of corneal staining between two regimens of high myopia–partial reduction orthokeratology (ortho-k) in children. Methods: The present clinical prospective study recruited 102 high-myopia subjects (204 eyes). These subjects were randomly divided into three groups: (1) ortho-k group 1, subjects with a target myopia reduction of 6.00 D; (2) ortho-k group 2, subjects with a target myopia reduction of 4.00 D; and (3) control group, the refractive error of subjects was corrected using a pair of single-vision spectacles. Vision acuity, refractive error, and the cornea were examined at baseline, and at 2 days, 1 week, 1, 3, 6, and 12 months after commencing lens wear. The measurement of the axial length of the eyeball and a corneal endothelium examination were performed at baseline and at 12 months. Results: The uncorrected vision acuities improved in subjects in these groups after treatment with ortho-k. Furthermore, the diopters of myopia and corneal curvature significantly decreased at 1 month, and the values continuously improved at 12 months, when compared with subjects at 1 month (P<0.05). Subjects in the control group had a significant increase in refractive error (0.565±0.313 D) and axial length (0.294±0.136 mm), when compared with subjects in the ortho-k–treated groups (P<0.05). However, there were no significant differences in changes in refractive error and axial length between ortho-k groups 1 (0.101±0.176 mm) and 2 (0.123±0.193 mm) at 12 months (P>0.05). Furthermore, subjects in group 1 (28.97%) had a higher rate of corneal staining, when compared with subjects in group 2 (13.06%) (P<0.05). Conclusion: The two ortho-k regimens, target reduction of 6.00 D and target of 4.00 D, had similar effects in controlling the increase in axial length and refractive error in high-myopia children. However, subjects with a target myopia reduction of 6.00 D had a higher rate of corneal staining than in subjects with a target myopia reduction of 4.00 D.