Estimates of Eddy Heat Flux Crossing the Antarctic Circumpolar Current from Observations in Drake Passage

The 4-yr measurements by current- and pressure-recording inverted echo sounders in Drake Passage produced statistically stable eddy heat flux estimates. Horizontal currents in the Antarctic Circumpolar Current (ACC) turn with depth when a depth-independent geostrophic current crosses the upper baroclinic zone. The dynamically important divergent component of eddy heat flux is calculated. Whereas full eddy heat fluxes differ greatly in magnitude and direction at neighboring locations within the local dynamics array (LDA), the divergent eddy heat fluxes are poleward almost everywhere. Case studies illustrate baroclinic instability events that cause meanders to grow rapidly. In the southern passage, where eddy variability is weak, heat fluxes are weak and not statistically significant. Vertical profiles of heat flux are surface intensified with ~50% above 1000 m and uniformly distributed with depth below. Summing poleward transient eddy heat transport across the LDA of −0.010 ± 0.005 PW with the stationary meander contribution of −0.004 ± 0.001 PW yields −0.013 ± 0.005 PW. A comparison metric, −0.4 PW, represents the total oceanic heat loss to the atmosphere south of 60°S. Summed along the circumpolar ACC path, if the LDA heat flux occurred at six “hot spots” spanning similar or longer path segments, this could account for 20%–70% of the metric, that is, up to −0.28 PW. The balance of ocean poleward heat transport along the remaining ACC path should come from weak eddy heat fluxes plus mean cross-front temperature transports. Alternatively, the metric −0.4 PW, having large uncertainty, may be high

High-pressure study on the superconducting pyrochlore oxide Cd2Re2O7

Superconducting and structural phase transitions in a pyrochlore oxide Cd2Re2O7 are studied under high pressure by x-ray diffraction and electrical resistivity measurements. A rich P-T phase diagram is obtained, which contains at least two phases with the ideal and slightly distorted pyrochlore structures. It is found that the transition between them is suppressed with increasing pressure and finally disappears at a critical pressure Pc = 3.5 GPa. Remarkable enhancements in the residual resistivity as well as the coefficient A of the AT 2 term in the resistivity are found around the critical pressure. Superconductivity is detected only for the phase with the structural distortion. It is suggested that the charge fluctuations of Re ions play a crucial role in determining the electronic properties of Cd2Re2O7.Comment: 5 pages, 5 figures, submitted to J. Phys. Soc. Jp

Mean Antarctic Circumpolar Current Transport Measured in Drake Passage

The Antarctic Circumpolar Current is an important component of the global climate system connecting the major ocean basins as it flows eastward around Antarctica, yet due to the paucity of data it remains unclear how much water is transported by the current. Between 2007 and 2011 flow through Drake Passage was continuously monitored with a line of moored instrumentation with unprecedented horizontal and temporal resolution. Annual mean near-bottom currents are remarkably stable from year to year. The mean depth-independent, or barotropic transport, determined from the near-bottom current meter records was 45.6 Sv with an uncertainty of 8.9 Sv. Summing the mean barotropic transport with the mean baroclinic transport relative to zero at the seafloor of 127.7 Sv gives a total transport through Drake Passage of 173.3 Sv. This new measurement is 30% larger than the canonical value often used as the benchmark for global circulation and climate models.Fil: Donohue, K. A.. University Of Rhode Island; Estados UnidosFil: Tracey, K. L.. University Of Rhode Island; Estados UnidosFil: Watts, D. R.. University Of Rhode Island; Estados UnidosFil: Chidichimo, María Paz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires; ArgentinaFil: Chereskin, T. K.. University of California at San Diego. Scripps Institution of Oceanography; Estados Unido

Zero-temperature generalized phase diagram of the 4d transition metals under pressure

We use an accurate implementation of density functional theory (DFT) to calculate the zero-temperature generalized phase diagram of the 4$d$ series of transition metals from Y to Pd as a function of pressure $P$ and atomic number $Z$. The implementation used is full-potential linearized augmented plane waves (FP-LAPW), and we employ the exchange-correlation functional recently developed by Wu and Cohen. For each element, we obtain the ground-state energy for several crystal structures over a range of volumes, the energy being converged with respect to all technical parameters to within $\sim 1$ meV/atom. The calculated transition pressures for all the elements and all transitions we have found are compared with experiment wherever possible, and we discuss the origin of the significant discrepancies. Agreement with experiment for the zero-temperature equation of state is generally excellent. The generalized phase diagram of the 4$d$ series shows that the major boundaries slope towards lower $Z$ with increasing $P$ for the early elements, as expected from the pressure induced transfer of electrons from $sp$ states to $d$ states, but are almost independent of $P$ for the later elements. Our results for Mo indicate a transition from bcc to fcc, rather than the bcc-hcp transition expected from $sp$-$d$ transfer.Comment: 28 pages and 10 figures. Submitted to Phys. Rev.

Mott-Superfluid transition in bosonic ladders

We show that in a commensurate bosonic ladder, a quantum phase transition occurs between a Mott insulator and a superfluid when interchain hopping increases. We analyse the properties of such a transition as well as the physical properties of the two phases. We discuss the physical consequences for experimental systems such as Josephson Junction arrays.Comment: 4 pages, 2 figures, revtex

Tight-binding study of high-pressure phase transitions in titanium: alpha to omega and beyond

We use a tight-binding total energy method, with parameters determined from a fit to first-principles calculations, to examine the newly discovered gamma phase of titanium. Our parameters were adjusted to accurately describe the alpha Ti-omega Ti phase transition, which is misplaced by density functional calculations. We find a transition from omega Ti to gamma Ti at 102 GPa, in good agreement with the experimental value of 116 GPa. Our results suggest that current density functional calculations will not reproduce the omega Ti-gamma Ti phase transition, but will instead predict a transition from omega Ti to the bcc beta Ti phase.Comment: 3 encapsulated Postscript figures, submitted to Phyical Review Letter

Decays of ℓ=1\ell=1 Baryons --- Quark Model versus Large-NcN_c

We study nonleptonic decays of the orbitally excited, \su6 \rep{70}-plet baryons in order to test the hypothesis that the successes of the nonrelativistic quark model have a natural explanation in the large-$N_c$ limit of QCD. By working in a Hartree approximation, we isolate a specific set of operators that contribute to the observed s- and d-wave decays in leading order in $1/N_c$. We fit our results to the current experimental decay data, and make predictions for a number of allowed but unobserved modes. Our tentative conclusion is that there is more to the nonrelativistic quark model of baryons than large-$N_c$.Comment: LaTeX 49pp. (38 pp. landscape), PicTex, PrePicTex, PostPicTex required for 3 figures, Harvard Preprint HUTP-94/A008. (Two additional operators are included, but conclusions are unchanged.

American Policy British Politics: Whole of Life Imprisonment and Transatlantic Influence

Since the abolition of the death penalty, life imprisonment in England and Wales has had a literal meaning with exceptional rarity. Now though, in the rejection of perceived interference by the European Court of Human Rights in domestic sentencing, the politics of whole of life imprisonment have become exposed, specifically, in the widening applicability of the tariff to those who kill police officers or prison guards. Borrowing from the politics of capital punishment in the USA, in both ‘acting out’ after a particular crime, and the prioritising of victim groups, the most severe penalty in England and Wales is increasingly beginning to mirror how the most severe punishment across the Atlantic is used, represented, and politicised

Lipophagy and Alcohol-Induced Fatty Liver

This review describes the influence of ethanol consumption on hepatic lipophagy, a selective form of autophagy during which fat-storing organelles known as lipid droplets (LDs) are degraded in lysosomes. During classical autophagy, also known as macroautophagy, all forms of macromolecules and organelles are sequestered in autophagosomes, which, with their cargo, fuse with lysosomes, forming autolysosomes in which the cargo is degraded. It is well established that excessive drinking accelerates intrahepatic lipid biosynthesis, enhances uptake of fatty acids by the liver from the plasma and impairs hepatic secretion of lipoproteins. All the latter contribute to alcohol-induced fatty liver (steatosis). Here, our principal focus is on lipid catabolism, specifically the impact of excessive ethanol consumption on lipophagy, which significantly influences the pathogenesis alcohol-induced steatosis. We review findings, which demonstrate that chronic ethanol consumption retards lipophagy, thereby exacerbating steatosis. This is important for two reasons: (1) Unlike adipose tissue, the liver is considered a fat-burning, not a fat-storing organ. Thus, under normal conditions, lipophagy in hepatocytes actively prevents lipid droplet accumulation, thereby maintaining lipostasis; (2) Chronic alcohol consumption subverts this fat-burning function by slowing lipophagy while accelerating lipogenesis, both contributing to fatty liver. Steatosis was formerly regarded as a benign consequence of heavy drinking. It is now recognized as the first hit in the spectrum of alcohol-induced pathologies that, with continued drinking, progresses to more advanced liver disease, liver failure, and/or liver cancer. Complete lipid droplet breakdown requires that LDs be digested to release their high-energy cargo, consisting principally of cholesteryl esters and triacylglycerols (triglycerides). These subsequently undergo lipolysis, yielding free fatty acids that are oxidized in mitochondria to generate energy. Our review will describe recent findings on the role of lipophagy in LD catabolism, how continuous heavy alcohol consumption affects this process, and the putative mechanism(s) by which this occurs