Search

False negative tests for SARS-CoV-2 are common and have important public health and medical implications. We tested the hypothesis of diurnal variation in viral shedding by assessing the proportion of positive versus negative SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) tests and cycle time (Ct) values among positive samples by the time of day. Among 86,342 clinical tests performed among symptomatic and asymptomatic patients in a regional health care network in the southeastern United States from March to August 2020, we found evidence for diurnal variation in the proportion of positive SARS-CoV-2 tests, with a peak around 1400 h and 1.7-fold variation over the day after adjustment for age, sex, race, testing location, month, and day of week and lower Ct values during the day for positive samples. These findings have important implications for public health testing and vaccination strategies. [ABSTRACT FROM AUTHOR]

Abstract: Landscape-scale measurements of PSII photochemical efficiency (ΔF/F m ′) by pulse-amplitude modulated (PAM) fluorometry were evaluated from 2006 to 2009 as a non-invasive method for monitoring the physiological condition of the seagrass, Thalassia testudinum Banks ex König, in Florida Bay, USA. Previous landscape-scale studies have shown that PAM-derived measurements of effective (ΔF/F m ′) and maximum (F v /F m ) photochemical efficiencies, as well as rapid light curves (RLC), exhibit significant diurnal variation. In this study, a regression approach was used to assess the magnitude of diurnal variation of ΔF/F m ′ versus irradiance at the bay scale and among 12 sample basins. Variation in ΔF/F m ′ versus irradiance reflects changes in the efficiency of dissipation of excess energy (photoprotection) and PSII inactivation (photodamage), which would be expected to vary with changes in physiological condition or photoacclimation state. ΔF/F m ′ significantly decreased with increasing irradiance at both the bay and basin scales. Regression slopes of ΔF/F m ′ versus irradiance were highly variable among years in 8 of the 12 sampled basins, ranging 5.6-fold from lowest to highest slopes. In contrast, regression derived y-intercepts varied only 1.7-fold over the 4-year period, but intercepts were significantly correlated with response slopes. Analyses of covariance indicated that diurnal response slopes significantly decreased from 2006 to 2009 at the bay scale, which corresponded to increasing water clarity and increased ambient irradiance at the leaf canopy as widespread phytoplankton blooms, which had initiated in the fall of 2005, dissipated. The results indicated a shift in the photo-acclimation state of T. testudinum with the cessation of phytoplankton blooms. They also suggest that regressions of ΔF/F m ′ versus irradiance, rather than absolute ΔF/F m ′ values, better reflect seagrass physiological condition when PAM-fluorescence measurements are obtained at landscape scales over diurnal periods. [Copyright &y& Elsevier]

Objective: By 2030 it is expected the elderly will comprise 25 percent of the drivers in the United States. It is also estimated that currently in the United States alone, 500 older adults are injured each day in motor vehicle crashes (MVCs). Current research has not been able to consistently produce a direct connection between MVCs and specific age-related changes. It is speculated that crash rates are more likely linked to an interaction between driver characteristics and driving conditions as well as the driving environment. Sundowner's syndrome occurs in older drivers starting in the late afternoon through early evening (generally between 3:00 pm and 8:00 pm) and involves behaviors such as confusion, disorientation, and restlessness. The following retrospective study was designed to assess the frequency of older drivers admitted to a trauma service due to an MVC based on the time of day of the MVC compared to younger and middle-aged drivers. Methods: The study included all adult trauma patients ≥ 21 years of age admitted to a Level 1 trauma center due to a, MVC, in which they were the driver of the vehicle, between January 1, 2005, and December 31, 2010. Results: A 3 (Injury Time Period) × 7 (Age Category) chi-square was performed to assess whether there was a disproportionate number of patients admitted as a function of time of injury and age. The overall chi-square was statistically significant. Consequently, a 3 × 7 analysis of variance (ANOVA) was performed on injury severity score (ISS). Tukey's posttest revealed that ISS was highest during the early evening time period. Conclusions: The evidence of the early evening time period having a differential impact on older drivers is through a demonstration of an Injury Time Period × Age Category interaction. This interaction was found to substantiate the hypothesis that older drivers have a disproportionately higher rate of injury due to an MVC during the early evening time period than younger and middle-aged drivers. In identifying the early evening's time period as a time in which older drivers are more likely to experience injury from an MVC than younger and middle-aged drivers, we believe that our research adds insight into why age restrictions have not been successful in reducing crash rates in the older driver population. It is the compound effect of age-related changes and environmental conditions that contributes to the higher proportion of MVCs. Age restrictions alone do not take into account environmental conditions. [ABSTRACT FROM PUBLISHER]

Abstract: Time integrated high-volume PM2.5 samples were collected separately during day and night from 1 August to 10 September 2008 at a paired urban (Atlanta)-rural (Yorkville) sites as part of the August Mini-Intensive Gas and Aerosol Study (AMIGAS). Selected filters (n =96, 48 for each site) were analyzed for a suite of water-soluble chemical species, including major inorganic ions, water-soluble organic carbon (WSOC), water-soluble total and inorganic nitrogen (WSTN and WSIN), and levoglucosan. Semi-continuous analyses of PM2.5 mass, soluble ions, WSOC, and gaseous O3, SO2, NO, NO2, NOy, CO, and meteorological parameters were also carried out in parallel. This study focuses on the characteristics of filterable water-soluble organic nitrogen (WSON), estimated by the difference in the measured concentrations of WSTN and WSIN, determined from aqueous filter extracts. At both sites, WSON varied from below the limit of detection (25ng-Nm−3) to ∼600ng-Nm−3 and on average contributed ∼10% to WSTN mass, with the majority of soluble nitrogen being ammonium (∼82%). WSON:WSOC (or N:C) mass ratios ranged between 0 and 27% at both the sites with a median value of ∼5%, similar to what has been reported in another study in the southeastern USA. At both the urban and rural sites median nighttime levels of WSON and N:C were observed to be consistently higher than daytime values. Based on correlation analyses, daytime WSON sources appeared different than nighttime sources, especially at the urban site. Overall, the data suggest the importance of coal-combustion (e.g., link to SO2), vehicle emissions, soil dust and biomass burning as WSON sources, and that nitrogenous organic compounds are likely a fairly small fraction of the secondary organic aerosol for this location during summer. [Copyright &y& Elsevier]

Natural volatile organic compound (VOC) fluxes were measured in three U.S. woodlands in summer 1993. Fluxes from individual leaves and branches were estimated with enclosure techniques and used to initialize and evaluate VOC emission model estimates. Ambient measurements were used to estimate above canopy fluxes for entire stands and landscapes.The branch enclosure experiments revealed 78 VOCs. Hexenol derivatives were the most commonly observed oxygenated compounds. The branch measurements also revealed high rates of isoprene emission from three genera of plants (Albizia, Chusqua and Mahonia) and high rates of monoterpene emission from three genera (Atriplex, Chrysthamnus and Sorbus) for which VOC emission rates have not been reported. Measurements on an additional 34 species confirmed previous results. Leaf enclosure measurements of isoprene emission rates from Quercus were substantially higher than the rates used in existing emission models.Model predictions of diurnal variations in isoprene fluxes were generally within ± 35% of observed flux variations. Measurements with a fast response analyzer demonstrated that 60 min is a reasonable time resolution for biogenic emission models. Average daytime stand scale (hundreds of m) flux measurements ranged from about 1.3 mg C m−2 h−1 for a shrub oak stand to 1.5–2.5 mg C m−2 h−1 for a mixed forest stand. Morning, evening and nighttime fluxes were less than 0.1 mg C m−2 h−1. Average daytime landscape scale (tens of km) flux measurements ranged from about 3 mg C m−2 h−1 for a shrub oak–aspen and rangeland landscape to about 7 mg C m−2 h−1 for a deciduous forest landscape. Fluxes predicted by recent versions (BEIS2, BEIS2.1) of a biogenic emission model were within 10 to 50% of observed fluxes and about 300% higher than those predicted by a previous version of the model (BEIS). [ABSTRACT FROM AUTHOR]

Microclimatic data are required for many problems in pure and applied ecology. This data includes aboveground convective and radiative conditions as well as soil temperature and moisture. In cold regions, the connection between above‐ and belowground microclimates via snow cover is also critically important. Here I describe a data set of hourly microclimates for the continental United States, simulated from the years 1979 to 2017 across a grid of 2,287 locations approximately 60 km apart. The data were generated with the NicheMapR microclimate model, driven by 0.04° gridded daily meteorological forcing data (air temperature, wind speed, humidity, solar radiation, air pressure, and rainfall). The aboveground microclimate variables include horizontal plane solar radiation, solar zenith angle, sky temperature (from which downwelling longwave radiation can be computed), air temperature, relative humidity, and wind speed at 1 and 200 cm height, and snow depth. The belowground variables include soil temperature, pore humidity, soil moisture, and soil water potential for 0, 2.5, 5, 10, 15, 20, 30, 50, 100, and 200 cm belowground. The computations are for four shade levels (0%, 50%, 75%, and 90%). The predictions are validated against detailed soil temperature, soil moisture, and snow observations and show enhanced performance over existing microclimatic data for the United States. The data set can be used for a wide variety of applications, including the computation of heat and water budgets of organisms, the potential for vegetation growth, and the computation of stress and growth indices. The use of daily forcing data also allows assessments of the consequences of extreme events including heat waves and drought. Example applications are provided for computing plant growth potential, lizard egg development and body temperature, and mammalian energy and water requirements. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper. [ABSTRACT FROM AUTHOR]

Introduction: Direct-to-consumer ads for testosterone replacement therapies have significantly increased over the past several years. Subsequently, testing for low serum testosterone has correspondingly increased., Aims: We sought to determine the testing behaviors of practitioners as well as the characteristics of men who are undergoing testing for low testosterone., Methods: Men aged 18-85 years were queried from the institutional electronic data warehouse from 2009 to 2012. Men were considered "tested" if their serum total testosterone level had been measured for any purpose. Tested men (TM) were compared with those not tested (NT)., Main Outcome Measures: The frequency and timing of testing for low testosterone as well as patient demographics and clinical characteristics were compared between TM and NT using multivariable logistic regression models., Results: Of the 321,674 total men, 10,133 (3.2%) underwent testing with a serum total testosterone (mean age of 55.2 ± 14.1 years). The frequency of testing increased from 2.5% to 3.6% during the study period (P < 0.001). Multivariable analysis demonstrated that TM were significantly (P < 0.001) more likely to be Caucasian and have increased body mass index. In addition, TM were significantly more likely to have comorbid conditions including decreased libido (adjusted odds ratio [aOR] 10.0, 95% confidence interval [CI] 8.5, 11.7), infertility (aOR 4.8, 95% CI 3.6, 6.6), erectile dysfunction (aOR 3.6, 95% CI 3.4, 3.8), osteoporosis (aOR 3.3, 95% CI 2.8, 3.8), depression (aOR 1.7, 95% CI 1.6, 1.8), prostate cancer (aOR 1.7, 95% CI 1.5, 1.8), hypertension (aOR 1.3. 95% CI 1.2, 1.4), chronic obstructive pulmonary disease (aOR 1.2, 95% CI 1.0, 1.4), and benign prostatic hyperplasia (aOR 1.2, 95% CI 1.1, 1.2). Among TM, only 889 (9%) men underwent testing between 7 am and 12 pm., Conclusions: The rate of testosterone testing is increasing with most testing practices directed toward a subset of men with comorbidities that are associated with hypogonadism. Compliance of physicians obtaining early morning serum testosterone levels is low. Further education of practitioners is required to appropriately test patients for hypogonadism., (© 2014 International Society for Sexual Medicine.)

The diurnal variability of Aureoumbra lagunensis, dissolved metals (Cd, Pb, Mn, Cr, Cu, Zn, Ni, Se, and Fe), and environmental parameters(salinity, temperature, turbidity, pH, and dissolved oxygen) were studied to understand the role of metals in the occurrence of the Texas'brown tide.' The A. lagunensis densities were high in the afternoon; suggesting the influence of light on the growth of A. lagunensis. The results indicate that metals, Cd, Pb, Mn, Cr, d Se may not be influencing the growth of A. lagunensis. The dissolved Cu, Zn, and Ni concentrations were inversely related with A. lagunensis densities whileFe Chad positive relationship with A. lagunensis. The spectroscopic characterization of the surfaces of A. lagunensis suggests that thesemetals might be playing a role in the occurrence of Texas 'brown tide' through involvement of -OH and -CH functional groups on the surfaces of A. [ABSTRACT FROM AUTHOR]