Residue-C effects on denitrification vary with soil depth

Peer reviewedPublisher PD

High Viral Fitness during Acute HIV-1 Infection

Several clinical studies have shown that, relative to disease progression, HIV-1 isolates that are less fit are also less pathogenic. The aim of the present study was to investigate the relationship between viral fitness and control of viral load (VL) in acute and early HIV-1 infection. Samples were obtained from subjects participating in two clinical studies. In the PULSE study, antiretroviral therapy (ART) was initiated before, or no later than six months following seroconversion. Subjects then underwent multiple structured treatment interruptions (STIs). The PHAEDRA study enrolled and monitored a cohort of individuals with documented evidence of primary infection. The subset chosen were individuals identified no later than 12 months following seroconversion to HIV-1, who were not receiving ART. The relative fitness of primary isolates obtained from study participants was investigated ex vivo. Viral DNA production was quantified using a novel real time PCR assay. Following intermittent ART, the fitness of isolates obtained from 5 of 6 PULSE subjects decreased over time. In contrast, in the absence of ART the fitness of paired isolates obtained from 7 of 9 PHAEDRA subjects increased over time. However, viral fitness did not correlate with plasma VL. Most unexpected was the high relative fitness of isolates obtained at Baseline from PULSE subjects, before initiating ART. It is widely thought that the fitness of strains present during the acute phase is low relative to strains present during chronic HIV-1 infection, due to the bottleneck imposed upon transmission. The results of this study provide evidence that the relative fitness of strains present during acute HIV-1 infection may be higher than previously thought. Furthermore, that viral fitness may represent an important clinical parameter to be considered when deciding whether to initiate ART during early HIV-1 infection

Impact of Days Fed on Holstein Bull and Steer Performance and Cutability of Cattle Pen- Fed Organic Diets

Performance, carcass characteristics, and total meat yield of Holstein bulls and steers were compared in a simulated organic production system with the goal of producing ground beef. Holstein bulls (n = 120, initial BW = 487 lb) and steers (n = 120, initial BW = 471 lb) of the same age were blocked by BW and assigned randomly to be harvested at 308, 343, 378, and 413 days on feed. After harvest, all meat o the carcass was considered trim and was collected and weighed to calculate total trim yield. Bulls gained faster and had greater live body weight, carcass weight, and trim yield than steers. Steers showed greater linear increases in marbling scores and fat composition of trim yield as days on feed increased than bulls. Increasing days on feed linearly increased feed intake, live body weight, carcass weight, and trim yield. Bulls had greater feed costs per animal than steers but castration had no effect on feed cost of gain. Feed cost per pound of trim yield increased linearly as days on feed increased. Feeding bulls may increase profitability in a ground beef production system that is not penalized for low quality beef

Survival, recruitment, and population growth rate of an important mesopredator: the northern raccoon.

Populations of mesopredators (mid-sized mammalian carnivores) are expanding in size and range amid declining apex predator populations and ever-growing human presence, leading to significant ecological impacts. Despite their obvious importance, population dynamics have scarcely been studied for most mesopredator species. Information on basic population parameters and processes under a range of conditions is necessary for managing these species. Here we investigate survival, recruitment, and population growth rate of a widely distributed and abundant mesopredator, the northern raccoon (Procyon lotor), using Pradel's temporal symmetry models and >6 years of monthly capture-mark-recapture data collected in a protected area. Monthly apparent survival probability was higher for females (0.949, 95% CI = 0.936-0.960) than for males (0.908, 95% CI = 0.893-0.920), while monthly recruitment rate was higher for males (0.091, 95% CI = 0.078-0.106) than for females (0.054, 95% CI = 0.042-0.067). Finally, monthly realized population growth rate was 1.000 (95% CI = 0.996-1.004), indicating that our study population has reached a stable equilibrium in this relatively undisturbed habitat. There was little evidence for substantial temporal variation in population growth rate or its components. Our study is one of the first to quantify survival, recruitment, and realized population growth rate of raccoons using long-term data and rigorous statistical models

Monthly recapture probability of northern raccoons (<i>Procyon lotor</i>) at the Ordway-Swisher Biological Station, Florida.

<p>Estimates and 95% confidence intervals are from model {φ(sex)<i>p</i>(month+sex)λ(season)}.</p

Model comparison table for Pradel’s temporal symmetry analysis of data collected from a population of northern raccoons (<i>Procyon lotor</i>) at the Ordway-Swisher Biological Station, Florida, from September 1992 to December 1998.

<p>We ran model sets investigating the effects of sex, time, month, season, and additive and interactive effects of sex with the other variables on four parameters: recapture probability, <i>p</i>; apparent survival probability, φ; recruitment rate, <i>f</i>; and realized population growth rate, λ. In section (A), we used the recruitment parameterization; in section (B), we used the lambda parameterization. Only the top ten models are included for each set. K is the number of parameters, AIC_c is Akaike’s Information Criterion corrected for small sample size, ΔAIC_c is the difference between each model’s AIC_c and the AIC_c of the top-ranked model, weight is the Akaike weight or model probability, and deviance is the model deviance.</p

(A) Monthly apparent survival probability, (B) monthly recruitment rate, and (C) monthly realized population growth rate of northern raccoons (<i>Procyon lotor</i>) at the Ordway-Swisher Biological Station, Florida.

<p>Estimates and 95% confidence intervals are from the top-ranked model that included season for each parameter: {φ(season+sex)<i>p</i>(month+sex)λ(season)} for survival, {φ(sex)<i>p</i>(month+sex)<i>f</i>(season+sex)} for recruitment, and {φ(sex)<i>p</i>(month+sex)λ(season)} for population growth rate.</p