An Atlas of Spectrophotometric Landolt Standard Stars

We present CCD observations of 102 Landolt standard stars obtained with the R-C spectrograph on the CTIO 1.5 m telescope. Using stellar atmosphere models we have extended the flux points to our six spectrophotometric secondary standards, in both the blue and the red, allowing us to produce flux-calibrated spectra that span a wavelength range from 3050 \AA to 1.1 \micron. Mean differences between UBVRI spectrophotometry computed using Bessell's standard passbands and Landolt's published photometry is found to be 1% or less. Observers in both hemispheres will find these spectra useful for flux-calibrating spectra and through the use of accurately constructed instrumental passbands be able to compute accurate corrections to bring instrumental magnitudes to any desired standard photometric system (S-corrections). In addition, by combining empirical and modeled spectra of the Sun, Sirius and Vega, we calculate and compare synthetic photometry to observed photometry taken from the literature for these three stars.Comment: Added referee's comments, minor corrections, replaced Table 1

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Validity of computed tomography defined body composition as a prognostic factor for functional outcome after kidney transplantation

BACKGROUND: The prevalence of sarcopenia is markedly higher in kidney transplant candidates than in the general population. It is a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength, which increases the risk of adverse postoperative outcomes.METHODS: We studied the impact of computed tomography defined preoperative sarcopenia, defined as a skeletal muscle index below age and gender specific cut-off values, on postoperative physical functional outcomes (grip strength, 4-m walking test, timed up and go, and sit to stand) at 6 months follow up.RESULTS: A total of 107 patients transplanted between 2015 and 2019 were included in this single-centre study. Mean age was 60.3 (±13.1), and 68.2% of patients were male. Ten patients (9.4%) were identified as sarcopenic. Sarcopenic patients were younger (55.6 (±15.1) vs. 60.8 (±12.9) years), more likely to be female (60.0% vs. 28.9%), and had an increased dialysis vintage (19 [2.5-32.8] vs. 9 [0.0-21.0] months) in comparison with their non-sarcopenic counterparts. In univariate analysis, they had a significantly lower body mass index and skeletal muscle area (P ≤ 0.001). In multivariate regression analysis, skeletal muscle index was significantly associated with grip strength (β = 0.690, R 2 = 0.232) and timed up and go performance (β = -0.070, R 2 = 0.154). CONCLUSIONS: We identified a significant association between sarcopenia existing pre-transplantation and poorer 6 months post-transplantation physical functioning with respect to hand grip strength and timed up and go tests in kidney transplant recipients. These results could be used to preoperatively identify patients with an increased risk of poor postoperative physical functional outcome, allowing for preoperative interventions to mitigate these risks.</p