β2 adrenergic agonists in acute lung injury? The heart of the matter

Despite extensive research into its pathophysiology, acute lung injury/acute respiratory distress syndrome (ALI/ARDS) remains a devastating syndrome with mortality approaching 40%. Pharmacologic therapies that reduce the severity of lung injury in vivo and in vitro have not yet been translated to effective clinical treatment options, and innovative therapies are needed. Recently, the use of β2 adrenergic agonists as potential therapy has gained considerable interest due to their ability to increase the resolution of pulmonary edema. However, the results of clinical trials of β agonist therapy for ALI/ARDS have been conflicting in terms of benefit. In the previous issue of Critical Care, Briot and colleagues present evidence that may help clarify the inconsistent results. The authors demonstrate that, in oleic acid lung injury in dogs, the inotropic effect of β agonists may recruit damaged pulmonary capillaries, leading to increased lung endothelial permeability

Gas Hydrate Formation Kinetics in the Presence of Surface-Active Agents

Gas hydrates are one group of clathrates consisting of host water and small guest molecules such as methane, ethane, propane, CO2, etc. The presence of high-pressure gas induces a three-dimensional network of hydrogen-bonded water cages. Humphry Davy first discovered gas hydrates in 1810. Since 1930’s, gas hydrates have been responsible for plugging natural gas process and transportation lines. Until now, research in the petroleum industry had been focused on avoiding the formation of gas hydrates. On the other hand, gas hydrates can play an important role in CO2 separation/sequestration and can also be used for natural gas storage purposes. But to apply gas hydrate techniques to industrial processes, we have to overcome the two barriers: (1) Gas hydrates are usually formed at the interface between the bulk gas and water phases. Once the solid hydrates cover the interface, gas hydrate formation decreases significantly because the hydrate layer becomes a barrier for mass transfer, and thus hydrate conversion is very low. (2) The rate of gas hydrate formation is very slow. To overcome these obstacles, people have employed a small amount of surfactants and the gas hydrate formation was accelerated several hundred times faster than water/gas systems. This talk will mainly concern the kinetic mechanism of methane hydrate formation when SDS is involved and will show that the SDS does not form micelles using an in-situ measurement of SDS concentrations. The role of SDS in accelerating methane hydrate formation will be understood by the SDS adsorption to hydrate particle surfaces using zetapotential and pyrene fluorescence measurements. Some aspects of other surface-active agents will also be discussed

Progress and Challenges of Implementing Decentralized HIV Testing For Prevention of Mother-to-Child Transmission of HIV - Myanmar.

BackgroundMyanmar has adopted point-of-care (POC) HIV testing for its prevention of mother-to-child transmission of HIV program, and was initiated in 84 townships in 2013. This study assessed the progress of HIV testing uptake from 2012, one year prior to POC testing, to 2015, and the challenges faced by service providers during the rapid rollout of this testing strategy.MethodsThis serial cross-sectional study included 23 townships randomly selected from the 84 townships. An open-question survey was used to collect information on the challenges faced by service providers. A random effects logistic model was used for assessing the progress of HIV testing uptake among urban and rural health center groups.ResultsHIV testing uptake for antenatal care (ANC) attendees increased from 60% to 90% for rural and from 70% to 90% for urban attendees. The proportion of ANC attendees who were tested at their first visit increased from 70% to 80% for rural and from 70% to 90% for urban attendees. In addition, the proportion receiving same-day test results increased from less than 10% to 90% for both groups. Major challenges faced during the initial rollout included low health awareness among pregnant women, fear of stigma and discrimination, long travel times and costs, and increased workloads of providers in rural settings.Conclusions and global health implicationsThe program should consider recruiting local volunteers to help reduce the workloads of service providers. Professional education based on need and continued mentoring and quality control schemes for HIV testing need to be in place. This decentralized strategy would be applicable to other resource-limited countries

RR Lyrae Luminosity Differences between Oosterhoff Group I and II Cluster Systems and the Origin of the Oosterhoff Dichotomy

We present a comparative study of the Oosterhoff II cluster M2 and the Oosterhoff I cluster M3. Both have similar metallicities, [Fe/H] = -1.62 for M2 and -1.66 for M3, but very different horizontal-branch (HB) morphologies (B-R)/(B + V + R) = 0.92 for M2 and 0.08 for M3. A period shift analysis and main-sequence fitting show that RRab variables in M2 are about 0.2 mag brighter than those in M3. Comparisons of the M2 period shift with Oosterhoff I clusters NGC 3201 and NGC 7006 also yield similar results, while a comparison between M2 and the Oosterhoff II cluster NGC 5986 reveals that the RR Lyrae luminosities are very similar. The luminosity difference is thought to be due to the evolutionary effect described in 1990 by Lee, Demarque, & Zinn: the M2 RRab variables have evolved away from the zero-age horizontal branch (ZAHB), while most M3 RRab variables lie near the ZAHB. A comparison of the mean period change rates of two clusters supports this hypothesis. Our relative age estimation using the difference in color between the base of giant branch and turn-off point shows that M2 is about 2 Gyr older than M3. Our result strongly suggests that the Oosterhoff dichotomy is due to age differences between Oosterhoff group I and II. This is consistent with the idea that the global second parameter is age. We discuss the kinematic differences between Oosterhoff group I and II clusters. Our result shows that the Oosterhoff group I clusters have zero or retrograde rotation with vrot = -68 ± 56 km s-1 and σlos = 131 ± 28 km s-1, while the Oosterhoff group II clusters have prograde rotation with vrot = +94 ± 47 km s-1 and σlos = 115 ± 29 km s-1, confirming a similar conclusion of van den Bergh. The difference in kinematics and ages between Oosterhoff group I and II clusters suggests that they may have different origins: The Oosterhoff II clusters were formed very early in the proto-Galaxy while the Oosterhoff I clusters were formed at different locations and at a later time, and were probably merger events. The period distributions of an unbiased sample of field RRab variables with | Z | ≤ 3 kpc and | Z | ≥ 5 kpc indicate that they may belong to different populations, with peak periods of 0.65 and 0.55 days, respectively. If the hypothesis that the Oosterhoff dichotomy is due to evolution is correct, then this period shift among the field RR Lyrae variables suggests that the RRab population with | Z | ≤ 3 kpc is somewhat older than the RRab population with | Z | ≥ 5 kpc. This also suggests different formation histories. In an appendix, we discuss that the frequently used Gaussian HB mass-dispersion rate (i.e., the mass-loss rate at the red giant branch [RGB] tip) in synthetic HB model calculations cannot fully explain the extended blue HB population and the pulsational properties of RR Lyrae variables in M2. Comparisons with synthetic HB models strongly suggests that an enhanced mass loss is required that extends the HB toward lower HB masses. We also discuss statistical effects on the metallicity estimate using P0,min for field RRab variables reported by Castellani, Maceroni, & Tosi in 1983. Our calculations suggest that the statistical effect is sufficient to explain the apparent gradient in P0,min without introducing a metallicity gradient

Accurate measurement of ^{13}C - ^{15}N distances with solid-state NMR

Solid-state NMR technique for measureing distances between hetero-nuclei in static powder samples is described. It is based on a two-dimensional single-echo scheme enhanced with adiabatic cross-polarization. As an example, the results for intra-molecular distances in $\alpha$-crystalline form of glycine are presented. The measured NMR distances ^13 C(2) - ^15 N and ^13 C(1) - ^15 N are 1.496 $\pm$ 0.002 \AA and 2.50 $\pm$ 0.02 \AA, respectively.Comment: 12 page

Black hole as an Information Eraser

We discuss the identity of black hole entropy and show that the first law of black hole thermodynamics, in the case of a Schwarzschild black hole, can be derived from Landauer's principle by assuming that the black hole is one of the most efficient information erasers in systems of a given temperature. The term "most efficient" implies that minimal energy is required to erase a given amount of information. We calculate the discrete mass spectra and the entropy of a Schwarzschild black hole assuming that the black hole processes information in unit of bits. The black hole entropy acquires a sub-leading contribution proportional to the logarithm of its mass-squared in addition to the usual mass-squared term without an artificial cutoff. We also argue that the minimum of the black hole mass is $\sqrt{\log 2/(8\pi)}M_P$.Comment: 12 pages, 4 figures, minor change