Acoustic characterization of encapsulated microbubbles at seismic frequencies

textEncapsulated microbubbles, whose diameters are on the order of microns, are widely used to provide acoustic contrast in biomedical applications. But well below the resonance frequencies of these microbubbles, any acoustic contrast is due solely to their relatively high compressibility compared to the surrounding medium. To estimate how well microbubbles may function as acoustic contrast agents in applications such as borehole logging or underground flow mapping, it must be determined how they behave both at atmospheric and down-well conditions, and how their presence affects the bulk acoustic properties of the surrounding medium, most crucially its specific acoustic impedance. Resonance tube experiments were performed on several varieties of acoustic contrast agents to determine their compressibility as a function of pressure and temperature, and the results are used to estimate the effect on sound propagation when they are introduced into rock formations.Mechanical Engineerin

Distribution and Abundance of the Kittlitz\u27s Murrelet \u3ci\u3eBrachyramphus brevirostris\u3c/i\u3e in Selected Areas of Southeastern Alaska

We conducted boat-based surveys for the Kittlitz’s Murrelet Brachyramphus brevirostris during the breeding season in southeastern Alaska from 2002 to 2009. We completed a single survey in seven areas and multiple annual surveys in three areas. Although surveys spanned a broad geographic area, from LeConte Bay in the south to the Lost Coast in the north (~655 km linear distance), roughly 79% of the regional population of Kittlitz’s Murrelet was found in and between Icy and Yakutat bays (~95 km linear distance). The congeneric Marbled Murrelet B. marmoratus outnumbered the Kittlitz’s Murrelet in all areas surveyed except Icy Bay; in fact, Kittlitz’s Murrelet abundance constituted a relatively small proportion (7%) of the total Brachyramphus murrelet abundance in our survey areas. In areas for which there are multiple years of survey data, Kittlitz’s Murrelet abundance varied considerably, whereas Marbled Murrelet abundance was comparatively stable during the same time period. Since the southern distribution of this species has likely narrowed over the last 50 years, and the distribution of the Kittlitz’s Murrelet appears to be restricted to glacially influenced marine waters in southeastern Alaska, we expect that any future changes in glacial extent will likely affect this species and its long-term persistence in the region

Supplementation with progestogens in the first trimester of pregnancy to prevent miscarriage in women with unexplained recurrent miscarriage: a systematic review and meta-analysis of randomized, controlled trials

OBJECTIVE: To investigate whether treatment with progestogens in the first trimester of pregnancy would decrease the incidence of miscarriage in women with a history of unexplained recurrent miscarriage. DESIGN: Systematic review and meta-analysis. SETTING: Not applicable. PATIENT(S): Women with a history of unexplained recurrent miscarriage. INTERVENTION(S): Randomized, controlled trials were identified by searching electronic databases. We included randomized, controlled trials comparing supplementation with progestogens (i.e., intervention group) in the first trimester of pregnancy with control (either placebo or no treatment) in women with a history of recurrent miscarriage. All types of progestogens, including natural P and synthetic progestins, were analyzed. MAIN OUTCOME MEASURE(S): The primary outcome was the incidence of miscarriage. The summary measures were reported as relative risk (RR) with 95% confidence interval (CI). RESULT(S): Ten trials including 1,586 women with recurrent miscarriage were analyzed. Eight studies used placebo as control and were double-blind. Regarding the intervention, two RCTs used natural P, whereas the other eight studies used progestins: medroxyprogesterone, cyclopentylenol ether of progesterone, dydrogesterone, or 17-hydroxyprogesterone caproate. Pooled data from the 10 trials showed that women with a history of unexplained recurrent miscarriage who were randomized to the progestogens group in the first trimester and before 16 weeks had a lower risk of recurrent miscarriage (RR 0.72, 95% CI 0.53-0.97) and higher live birth rate (RR 1.07, 95% CI 1.02-1.15) compared with those who did not. No statistically significant differences were found in the other secondary outcomes, including preterm birth (RR 1.09, 95% CI 0.71-1.66), neonatal mortality (RR 1.80, 95% CI 0.44-7.34), and fetal genital abnormalities (RR 1.68, 95% CI 0.22-12.62). CONCLUSION(S): Our findings provide evidence that supplementation with progestogens may reduce the incidence of recurrent miscarriages and seem to be safe for the fetuses. Synthetic progestogens, including weekly IM 17-hydroxyprogesterone caproate, but not natural P, were associated with a lower risk of recurrent miscarriage. Given the limitations of the studies included in our meta-analysis, it is difficult to recommend route and dose of progestogen therapy. Further head-to-head trials of P types, dosing, and route of administration are required

A Response to the IPCC Fifth Assessment

The Intergovernmental Panel on Climate Change\u27s (IPCC) Fifth Assessment Report presented significant data and findings about climate change. But the IPCC\u27s working groups\u27 summaries for policymakers avoid making normative statements about the IPCC\u27s findings. The authors, members of the Environmental Law Collaborative, bridge this gap by identifying the normative claims that stem from the working groups\u27 summaries to spark deeper discussion and help shape the IPCC\u27s sixth assessment

A Response to the IPCC Fifth Assessment

This collection of essays is the initial product of the second meeting of the Environmental Law Collaborative, a group of environmental law scholars that meet to discuss important and timely environmental issues. Here, the group provides an array of perspectives arising from the Fifth Assessment of the Intergovernmental Panel on Climate Change. Each scholar chose one passage from one of the IPCC’s three Summaries for Policymakers as a jumping-off point for exploring climate change issues and responding directly to the reports. The result is a variety of viewpoints on the future of how law relates to climate change, a result that is the product not only of each scholar’s individual knowledge but also of the group’s robust discussion

Homotopy equivalence and hemeomorphism of 3-manifolds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29969/1/0000331.pd

A Response to the IPCC Fifth Assessment

This collection of essays is the initial product of the second meeting of the Environmental Law Collaborative, a group of environmental law scholars that meet to discuss important and timely environmental issues. Here, the group provides an array of perspectives arising from the Fifth Assessment of the Intergovernmental Panel on Climate Change. Each scholar chose one passage from one of the IPCC’s three Summaries for Policymakers as a jumping-off point for exploring climate change issues and responding directly to the reports. The result is a variety of viewpoints on the future of how law relates to climate change, a result that is the product not only of each scholar’s individual knowledge but also of the group’s robust discussion