"Pathogen Eradication" and "Emerging Pathogens": Difficult Definitions in Cystic Fibrosis.

Infection is a common complication of cystic fibrosis (CF) airway disease. Current treatment approaches include early intervention with the intent to eradicate pathogens in the hope of delaying the development of chronic infection and the chronic use of aerosolized antibiotics to suppress infection. The use of molecules that help restore CFTR (cystic fibrosis transmembrane conductance regulator) function, modulate pulmonary inflammation, or improve pulmonary clearance may also influence the microbial communities in the airways. As the pipeline of these new entities continues to expand, it is important to define when key pathogens are eradicated from the lungs of CF patients and, equally important, when new pathogens might emerge as a result of these novel therapies

Sexual selection on male vocal fundamental frequency in humans and other anthropoids

D.A.P. was supported by a National Institutes of Mental Health T32 MH70343-05 fellowship. J.R.W. was supported by a National Science Foundation predoctoral fellowship.In many primates, including humans, the vocalizations of males and females differ dramatically, with male vocalizations and vocal anatomy often seeming to exaggerate apparent body size. These traits may be favoured by sexual selection because low-frequency male vocalizations intimidate rivals and/or attract females, but this hypothesis has not been systematically tested across primates, nor is it clear why competitors and potential mates should attend to vocalization frequencies. Here we show across anthropoids that sexual dimorphism in fundamental frequency (F0) increased during evolutionary transitions towards polygyny, and decreased during transitions towards monogamy. Surprisingly, humans exhibit greater F0 sexual dimorphism than any other ape. We also show that low-F0 vocalizations predict perceptions of men’s dominance and attractiveness, and predict hormone profiles (low cortisol and high testosterone) related to immune function. These results suggest that low male F0 signals condition to competitors and mates, and evolved in male anthropoids in response to the intensity of mating competition.PostprintPeer reviewe

Magnetic resonance imaging phantoms for quality-control of myocardial T1 and ECV mapping: specific formulation, long-term stability and variation with heart rate and temperature

Background: Magnetic resonance imaging (MRI) phantoms are routinely used for quality assurance in MRI centres; however their long term stability for verification of myocardial T1/ extracellular volume fraction (ECV) mapping has never been investigated. Methods: Nickel-chloride agarose gel phantoms were formulated in a reproducible laboratory procedure to mimic blood and myocardial T1 and T2 values, native and late after Gadolinium administration as used in T1/ECV mapping. The phantoms were imaged weekly with an 11 heart beat MOLLI sequence for T1 and long TR spin-echo sequences for T2, in a carefully controlled reproducible manner for 12 months. Results: There were only small relative changes seen in all the native and post gadolinium T1 values (up to 9.0 % maximal relative change in T1 values) or phantom ECV (up to 8.3 % maximal relative change of ECV, up to 2.2 % maximal absolute change in ECV) during this period. All native and post gadolinium T2 values remained stable over time with <2 % change. Temperature sensitivity testing showed MOLLI T1 values in the long T1 phantoms increasing by 23.9 ms per degree increase and short T1 phantoms increasing by 0.3 ms per degree increase. There was a small absolute increase in ECV of 0.069 % (~0.22 % relative increase in ECV) per degree increase. Variation in heart rate testing showed a 0.13 % absolute increase in ECV (~0.45 % relative increase in ECV) per 10 heart rate increase. Conclusions: These are the first phantoms reported in the literature modeling T1 and T2 values for blood and myocardium specifically for the T1mapping/ECV mapping application, with stability tested rigorously over a 12 month period. This work has significant implications for the utility of such phantoms in improving the accuracy of serial scans for myocardial tissue characterisation by T1 mapping methods and in multicentre work

Estrogen and Progestogen Correlates of the Structure of Female Copulation Calls in Semi-Free-Ranging Barbary Macaques (Macaca sylvanus)

Females of many Old World primates produce conspicuous vocalizations in combination with copulations. Indirect evidence exists that in Barbary macaques (Macaca sylvanus), the structure of these copulation calls is related to changes in reproductive hormone levels. However, the structure of these calls does not vary significantly around the timing of ovulation when estrogen and progestogen levels show marked changes. We here aimed to clarify this paradox by investigating how the steroid hormones estrogen and progesterone are related to changes in the acoustic structure of copulation calls. We collected data on semi-free-ranging Barbary macaques in Gibraltar and at La Forêt des Singes in Rocamadour, France. We determined estrogen and progestogen concentrations from fecal samples and combined them with a fine-grained structural analysis of female copulation calls (N = 775 calls of 11 females). Our analysis indicates a time lag of 3 d between changes in fecal hormone levels, adjusted for the excretion lag time, and in the acoustic structure of copulation calls. Specifically, we found that estrogen increased the duration and frequency of the calls, whereas progestogen had an antagonistic effect. Importantly, however, variation in acoustic variables did not track short-term changes such as the peak in estrogen occurring around the timing of ovulation. Taken together, our results help to explain why female Barbary macaque copulation calls are related to changes in hormone levels but fail to indicate the fertile phase

Electro-oxidation of carbon monoxide on well-ordered Pt(111)/Sn surface alloys

The electro-oxidation of CO on model platinum-tin alloy catalysts has been studied by ex-situ electrochemical measurements following the preparation of the Pt(111)/Sn(2x2) and Pt(111)/Sn(?3x?3)-R30° surfaces. A surface redox couple, which is associated with the adsorption/desorption of hydroxide on the Sri sites, is observed at 0.28 V-RHE/0.15 V-RHE in H2SO4 electrolyte on both surfaces. Evidence that it is associated with the adsorption of OH comes from ex-situ photoemission measurements, which indicate that the Sri atoms are in a metallic state at potentials below 0.15 V-RHE and an oxidized state at potentials above 0.28 V-RHE. Specific adsorption of sulfate anions is not associated with the surface process since there is no evidence from photoemission of sulfate adsorption, and the same surface couple is observed in the HClO4 electrolyte. CO is adsorbed from solution at 300 K, with saturation coverages of 0.37 ± 0.05 and 0.2 ± 0.05 ML, respectively. The adsorbed CO is oxidatively stripped at the potential coincident with the adsorption of hydroxide on the tin sites, viz., 0.28 V-RHE. This strong promotional effect is unambiguously associated with the bifunctional mechanism. The Sn-induced activation of water, and promotion of CO electro-oxidation, is sustained as long as the alloy structure remains intact, in the potential range below 0.5 V-RHE. The results are discussed in the light of the requirements for CO-tolerant platinum-based electrodes in hydrogen fuel cell anode catalysts and catalysts for direct methanol electro-oxidation

The stability and electro-oxidation of carbon monoxide on model electrocatalysts: Pt(111)-Sn(2 x 2) and Pt(111)-Sn(root/3 x \root 3)R30 degrees

The surface redox behaviour, the stability, and the electro-oxidation of CO on model platinum-tin surface alloy catalysts has been studied by ex situ electrochemical measurements. The Pt(111)-Sn(2 x 2) and Pt(111)-Sn(root3 x root3)R30degrees surfaces have been prepared and characterised in UHV by vapour deposition of Sri on Pt(111) and the surfaces subsequently transferred for electrochemical investigation. A surface redox couple, which is associated with the adsorption/desorption of hydroxide on the Sn sites, is observed at 0.28V(RHE)/0.15V(RHE) in H2SO4 electrolyte on both surfaces. Evidence that it is associated with the adsorption of OH comes from ex situ photoemission measurements, which indicate that the Sri atoms are in a metallic state at potentials below 0.15V(RHE), and an oxidised state at potentials above 0.28(RHE). Specific adsorption of sulphate anions is not associated with the surface process since there is no evidence from photoemission of sulphate adsorption, and the same surface couple is observed in HClO4 electrolyte. A second surface redox couple, associated with further oxidation of the Sn sites in the alloy surfaces. is observed at 0.8V(RHE)/0.58V(RHE) . CO is adsorbed from solution at 300 K, with saturation coverages of 0.37 +/- 0.05 ML and 0.2 +/- 0.05 ML. respectively. The adsorbed CO is oxidatively stripped at the potential coincident with the adsorption of hydroxide on the tin sites at the lower potential of 0.28V(RHE). This strong promotional effect is unambiguously associated with the bi-functional mechanism. The Sri induced activation of water. and promotion of CO electro-oxidation, is sustained as long as the alloy structure remains intact, in the potential range below 0.5V(RHE). The instability of the alloy surface at higher potentials is associated with the second redox couple. The redox behaviour at higher potentials is modified by the presence of CO in stripping experiments, with couples now observed at 0.78V(RHE)/0.56V(RHE), and 0.9V(RHE)/0.70V(RHE). This behaviour may be associated with enhanced oxidation through the exclusion of sulphate anions at the surface by CO

The electro-oxidation of carbon monoxide on ruthenium modified Pt(1 1 1)

The effect of adsorbed ruthenium sub-monolayers on Pt(1 1 1) on the electro-oxidation of CO has been investigated using ultra-hight vacuum-electrochemical transfer techniques. Overlayers of metal vapour deposited (MVD) ruthenium were characterised using a combination of LEED, LEISS and XPS. Nucleation and growth of ruthenium clusters on the Pt(1 1 1) surface takes place during deposition at 300 K from low coverages. Bulk dissolution occurs only after annealing the surface to temperatures in excess of 900 K.The hydrogen and anion adsorption/desorption behaviour, and the oxidative stripping of saturated CO overlayers, in 0.5 M sulphuric acid electrolyte on the ruthenium modified Pt(1 1 1) surfaces has been investigated using cyclic voltammetry. The long range order characteristics of the voltammetry of the Pt(1 1 1) surface associated with the anion adsorption is destroyed by the lowest coverages of ruthenium. The hydrogen adsorption/desorption behaviour remains dominated by that of Pt(1 1 1), however, throughout the ruthenium sub-monolayer regime. At ruthenium coverages above one monolayer, the redox currents in the double layer region increase, and peaks we associate with hydrogen adsorption on ruthenium are apparent at 0.09 and 0.16 V vs reversible hydrogen electrode (RHE).CO electro-oxidation on Pt(1 1 1) modified by ruthenium is characterised by two oxidation peaks (?0.6 and 0.7 V RHE) in the stripping voltammetry, both at an over-potential significantly lower than that found on Pt(1 1 1) under the same conditions. This overall promotion is associated with the bi-functional mechanism, and the reduction in over-potential is primarily associated with the promoted activation of water at the ruthenium atoms in the cluster. The first of the two promoted oxidation peaks (0.6 V) is a result of fast Langmuir–Hinshelwood oxidation kinetics associated with platinum sites adjacent to the ruthenium cluster (Zone I). The second oxidation peak (0.7 V) is associated with oxidation of CO in the remaining sites that lie at least one platinum atom away from the ruthenium sites (Zone II). We show that the mobility of CO between these sites is relatively low in the presence of the sulphate anion: the diffusion of CO between sites is not responsible for the second peak in the stripping voltammetry. We suggest that the slower kinetics of the oxidation in the second peak is associated with the rate of spill-over and diffusion of the oxidant produced at the ruthenium sites to Zone I sites

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A combinatorial approach to the study of particle size effects on supported electrocatalysts: oxygen reduction on gold

A novel high-throughput technique has been developed for the investigation of the influence of supported metal particle size and the support on electrocatalytic activity. Arrays with a gradation of catalyst particle sizes are fabricated in a physical vapor deposition system that also allows selection of the support material. Simultaneous electrochemical measurements at all electrodes in the array, together with determination of the actual particle size distribution on each of the electrodes by transmission electron microscopy (TEM), then allows rapid determination of the activity as a function of catalyst center size. The procedure is illustrated using data for the reduction of oxygen on gold nanoparticles supported on both substoichiometric titanium dioxide (TiOx) and carbon and the conclusions are verified using voltammetry at rotating disk electrodes. Gold centers with diameters in the range 1.4-6.3 nm were investigated and it is demonstrated that, with both supports, the catalytic activity for oxygen reduction decays rapidly for particle sizes below 3.0 nm. This may be observed as a decrease in current at constant potential or an increase in the overpotential for oxygen reduction