Louisiana Birds Act as Reservoirs for Antibiotic-resistant Bacteria

Wild birds carry diverse microbial communities, including antibiotic-resistant bacteria (ARB). With the ever-increasing use of antibiotics in agricultural and clinical settings, genes that code for antibiotic resistance in bacteria have been selected for. These bacteria persist in the environment in a culturable state, but little is understood about communities of antibiotic-resistant bacteria in the environment. Birds with predictable behaviors may serve as useful indicators of these communities, and provide insights into how bacterial communities spread and evolve in the environment. To understand the utility of birds as indicators of the presence of antibiotic-resistant bacteria in the environment, we collected bacterial samples from forest birds in a cypress-tupelo/bottomland hardwood forest fragment surrounded by urban Baton Rouge, Louisiana. Densities of total and antibiotic-resistant bacteria varied by bird sex, age group, and foraging guild. Specifically, female birds had a higher prevalence of antibiotic-resistant bacteria than males, juvenile birds carried higher densities of antibiotic-resistant bacteria than adult birds, and tree-foraging birds carried higher densities than did ground-foraging birds. These data suggest that specific behaviors from each group may be associated with higher colonization by antibiotic-resistant bacteria and that birds may be useful indicators of contamination by viable potential pathogens in the environment. In a separate analysis, we sequenced the 16S rRNA gene from almost 100 isolates and used BLASTn analysis to determine the lowest possible taxonomic level for each sequence. We found that there were four orders of bacteria present from all of our samples; Lactobacillales, Pseudomonadales, Bacillales, and Enterbacterales. The Louisiana birds sampled in this study yielded a diverse array of bacteria, and highlighted the importance of future studies of antibiotic-resistant bacteria in birds

On the size of the Fe II emitting region in the AGN Akn 120

We present a reverberation analysis of the strong, variable optical Fe II emission bands in the spectrum of Akn 120, a low-redshift AGN which is one of the best candidates for such a study. On time scales of several years the Fe II line strengths follow the variations in the continuum strength. However, we are unable to measure a clear reverberation lag time for these Fe II lines on any time scale. This is due to the very broad and flat-topped nature of the Fe II cross correlation functions, as compared to the H-beta response which is much more sharply localized in time. Although there is some suggestion in the light curve of a 300-day response time, our statistical analysis does not pick up such a feature. We conclude that the optical Fe II emission does not come from a photoionization-powered region similar in size to the H-beta emitting region, but we cannot say for sure where it does come from. Our results are generally consistent either with emission from a photoionized region several times larger than the H-beta zone, or with emission from gas heated by some other means, perhaps responding only indirectly to the continuum variations.Comment: Accepted for publication in the Ap

Na atomic order, Co charge disproportionation and magnetism in Nax_{x}CoO2_{2} for large Na contents

We have synthesized and characterized four different stable phases of Na ordered Na$_{x}$CoO$_{2}$, for $0.65<x<0.8$. Above 100 K they display similar Curie-Weiss susceptibilities as well as ferromagnetic $q=0$ spin fluctuations in the CoO$_{2}$ planes revealed by $^{23}$Na NMR data. In all phases from $^{59}$Co NMR data we display evidences that the Co disproportionate already above 300 K into non magnetic Co$^{3+}$ and magnetic $\approx$Co$^{3.5+}$ sites on which holes delocalize. This allows us to understand that metallic magnetism is favored for these large Na contents. Below 100 K the phases differentiate, and a magnetic order sets in only for $x\gtrsim 0.75$ at $T_{N}=$22 K. We suggest that the charge order also governs the low $T$ energy scales and transverse couplings

Strategy training enhances memory performance in single task but not in dual tasking: preliminary results

Research Objectives: This study tests the hypothesis that strategy training improves memory performance in single task. It also investigates whether the effect is observed in dual tasking. Design/Method: A repeated-measures design was employed. Two groups of participants performed a memory task and a secondary auditory discrimination task individually, and a dual-task which combined both. The experimental group (N=7) were then taught strategies such as association/imagery, while the control group (N=6) received no training. Number of words recalled from a word list and reaction time for the auditory discrimination task were recorded pre and post training. Results: Following training the words recalled was significantly increased in the single-task condition but not in the dual-task condition. As expected, there was no significant increase in words recalled in either condition for the control group. Secondary task performance was not significantly affected by strategy training. Conclusions: The use of strategies may contribute to improve memory for simple tasks primarily

Age Dating of a High-Redshift QSO B1422+231 at Z=3.62 and its Cosmological Implications

The observed Fe II(UV+optical)/Mg II lambda lambda 2796,2804 flux ratio from a gravitationally lensed quasar B1422+231 at z=3.62 is interpreted in terms of detailed modeling of photoionization and chemical enrichment in the broad-line region (BLR) of the host galaxy. The delayed iron enrichment by Type Ia supernovae is used as a cosmic clock. Our standard model, which matches the Fe II/Mg II ratio, requires the age of 1.5 Gyr for B1422+231 with a lower bound of 1.3 Gyr, which exceeds the expansion age of the Einstein-de Sitter Omega_0=1 universe at a redshift of 3.62 for any value of the Hubble constant in the currently accepted range, H_0=60-80 km,s^{-1},Mpc^{-1}. This problem of an age discrepancy at z=3.62 can be unraveled in a low-density Omega_0<0.2 universe, either with or without a cosmological constant, depending on the allowable redshift range of galaxy formation. However, whether the cosmological constant is a required option in modern cosmology awaits a thorough understanding of line transfer processes in the BLRs.Comment: 7 pages including 3 figures, to appear in ApJ Letter