Characteristics of Veterans With Depression Who Use the Veterans Choice Program of the Veterans Health Administration.

Objective: The Veterans Choice Program (VCP) of the Veterans Health Administration (VHA) allowed eligible veterans to use their benefits with participating providers outside the VHA. The authors aimed to identify characteristics of veterans with depression who used or did not use mental health care through the VCP.

Methods: In this cross-sectional study, the authors analyzed secondary data from the national VHA Corporate Data Warehouse.

The NEON Daily Isotopic Composition of Environmental Exchanges Dataset.

The National Ecological Observatory Network (NEON) provides open-access measurements of stable isotope ratios in atmospheric water vapor (δH, δO) and carbon dioxide (δC) at different tower heights, as well as aggregated biweekly precipitation samples (δH, δO) across the United States. These measurements were used to create the NEON Daily Isotopic Composition of Environmental Exchanges (NEON-DICEE) dataset estimating precipitation (P; δH, δO), evapotranspiration (ET; δH, δO), and net ecosystem exchange (NEE; δC) isotope ratios. Statistically downscaled precipitation datasets were generated to be consistent with the estimated covariance between isotope ratios and precipitation amounts at daily time scales.

Heterogeneous isotope effects decouple conifer leaf and branch sugar δO and δC.

Isotope ratios of tree-ring cellulose are a prominent tool to reconstruct paleoclimate and plant responses to environmental variation. Current models for cellulose isotope ratios assume a transfer of the environmental signals recorded in bulk leaf water to carbohydrates and ultimately into stem cellulose. However, the isotopic signal of carbohydrates exported from leaf to branch may deviate from mean leaf values if spatial heterogeneity in isotope ratios exists in the leaf.

Seasonal and diurnal trends in progressive isotope enrichment along needles in two pine species.

The Craig-Gordon type (C-G) leaf water isotope enrichment models assume a homogeneous distribution of enriched water across the leaf surface, despite observations that Δ O can become increasingly enriched from leaf base to tip. Datasets of this 'progressive isotope enrichment' are limited, precluding a comprehensive understanding of (a) the magnitude and variability of progressive isotope enrichment, and (b) how progressive enrichment impacts the accuracy of C-G leaf water model predictions. Here, we present observations of progressive enrichment in two conifer species that capture seasonal and diurnal variability in environmental conditions.