Direct determination of the air-sea CO₂ gas transfer velocity in Arctic sea-ice regions

The Arctic Ocean is an important sink for atmospheric CO₂. The impact of decreasing sea-ice extent and expanding marginal ice zones on Arctic air-sea CO₂ exchange depends on the rate of gas transfer in the presence of sea ice. Sea ice acts to limit air-sea gas exchange by reducing contact between air and water, but is also hypothesised to enhance gas transfer rates across surrounding open water surfaces through physical processes such as increased surface-ocean turbulence from ice-water shear and ice-edge form drag. Here we present the first direct determination of the CO₂ air-sea gas transfer velocity in a wide range of Arctic sea-ice conditions. We show that the gas transfer velocity increases near-linearly with decreasing sea-ice concentration. We also show that previous modeling approaches overestimate gas transfer rates in sea-ice regions

Targeted Deletion of Kcne2 Causes Gastritis Cystica Profunda and Gastric Neoplasia

Gastric cancer is the second leading cause of cancer death worldwide. Predisposing factors include achlorhydria, Helicobacter pylori infection, oxyntic atrophy and TFF2-expressing metaplasia. In parietal cells, apical potassium channels comprising the KCNQ1 α subunit and the KCNE2 β subunit provide a K+ efflux current to facilitate gastric acid secretion by the apical H+K+ATPase. Accordingly, genetic deletion of murine Kcnq1 or Kcne2 impairs gastric acid secretion. Other evidence has suggested a role for KCNE2 in human gastric cancer cell proliferation, independent of its role in gastric acidification. Here, we demonstrate that 1-year-old Kcne2−/− mice in a pathogen-free environment all exhibit a severe gastric preneoplastic phenotype comprising gastritis cystica profunda, 6-fold increased stomach mass, increased Ki67 and nuclear Cyclin D1 expression, and TFF2- and cytokeratin 7-expressing metaplasia. Some Kcne2−/−mice also exhibited pyloric polypoid adenomas extending into the duodenum, and neoplastic invasion of thin walled vessels in the sub-mucosa. Finally, analysis of human gastric cancer tissue indicated reduced parietal cell KCNE2 expression. Together with previous findings, the results suggest KCNE2 disruption as a possible risk factor for gastric neoplasia

HIV treatment as prevention: optimising the impact of expanded HIV treatment programmes.

Until now, decisions about how to allocate ART have largely been based on maximising the therapeutic benefit of ART for patients. Since the results of the HPTN 052 study showed efficacy of antiretroviral therapy (ART) in preventing HIV transmission, there has been increased interest in the benefits of ART not only as treatment, but also in prevention. Resources for expanding ART in the short term may be limited, so the question is how to generate the most prevention benefit from realistic potential increases in the availability of ART. Although not a formal systematic review, here we review different ways in which access to ART could be expanded by prioritising access to particular groups based on clinical or behavioural factors. For each group we consider (i) the clinical and epidemiological benefits, (ii) the potential feasibility, acceptability, and equity, and (iii) the affordability and cost-effectiveness of prioritising ART access for that group. In re-evaluating the allocation of ART in light of the new data about ART preventing transmission, the goal should be to create policies that maximise epidemiological and clinical benefit while still being feasible, affordable, acceptable, and equitable

Non Fermi liquid ground states in strongly correlated f-electron materials

Experimental efforts to characterize and develop an understanding of non Fermi liquid (NFL) behavior at low temperature in f-electron materials are reviewed for three f-electron systems: M 1−x U x Pd 3 (M = Sc, Y), U 1−x Th x Pd 2 Al 3 , and UCu 5−x Pd x . The emerging systematics of NFL behavior in f-electron systems, based on the present sample of nearly ten f-electron systems, is updated. Many of the f-electron systems exhibit the following temperature dependences of the electrical resistivity p, specific heat C, and magnetic susceptibility χ for T ≪ T 0 , where T o is a characteristic temperature: P(T) ∼ 1 – aT/T 0 , where a 0, C(T)/T ∼ (-1/ T o ) In ( T/bT 0 ), and χ(T) ∼ 1 − c (T/T o ) 1/2 . In several of the f-electron systems, the characteristic temperature T o can be identified with the Kondo temperature T k .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44962/1/10909_2004_Article_BF00752290.pd