Equilibration rates in a strongly coupled nonconformal quark-gluon plasma

We initiate the study of equilibration rates of strongly coupled quark-gluon plasmas in the absence of conformal symmetry. We primarily consider a supersymmetric mass deformation within ${\cal N}=2^{*}$ gauge theory and use holography to compute quasinormal modes of a variety of scalar operators, as well as the energy-momentum tensor. In each case, the lowest quasinormal frequency, which provides an approximate upper bound on the thermalization time, is proportional to temperature, up to a pre-factor with only a mild temperature dependence. We find similar behaviour in other holographic plasmas, where the model contains an additional scale beyond the temperature. Hence, our study suggests that the thermalization time is generically set by the temperature, irrespective of any other scales, in strongly coupled gauge theories.Comment: 6 pages, 7 figure

sQGP as hCFT

We examine the proposal to make quantitative comparisons between the strongly coupled quark-gluon plasma and holographic descriptions of conformal field theory. In this note, we calculate corrections to certain transport coefficients appearing in second-order hydrodynamics from higher curvature terms to the dual gravity theory. We also clarify how these results might be consistently applied in comparisons with the sQGP.Comment: 13 page

Entanglement, Holography and Causal Diamonds

We argue that the degrees of freedom in a d-dimensional CFT can be re-organized in an insightful way by studying observables on the moduli space of causal diamonds (or equivalently, the space of pairs of timelike separated points). This 2d-dimensional space naturally captures some of the fundamental nonlocality and causal structure inherent in the entanglement of CFT states. For any primary CFT operator, we construct an observable on this space, which is defined by smearing the associated one-point function over causal diamonds. Known examples of such quantities are the entanglement entropy of vacuum excitations and its higher spin generalizations. We show that in holographic CFTs, these observables are given by suitably defined integrals of dual bulk fields over the corresponding Ryu-Takayanagi minimal surfaces. Furthermore, we explain connections to the operator product expansion and the first law of entanglement entropy from this unifying point of view. We demonstrate that for small perturbations of the vacuum, our observables obey linear two-derivative equations of motion on the space of causal diamonds. In two dimensions, the latter is given by a product of two copies of a two-dimensional de Sitter space. For a class of universal states, we show that the entanglement entropy and its spin-three generalization obey nonlinear equations of motion with local interactions on this moduli space, which can be identified with Liouville and Toda equations, respectively. This suggests the possibility of extending the definition of our new observables beyond the linear level more generally and in such a way that they give rise to new dynamically interacting theories on the moduli space of causal diamonds. Various challenges one has to face in order to implement this idea are discussed.Comment: 84 pages, 12 figures; v2: expanded discussion on constraints in section 7, matches published versio

Clustering Analyses of 300,000 Photometrically Classified Quasars--II. The Excess on Very Small Scales

We study quasar clustering on small scales, modeling clustering amplitudes using halo-driven dark matter descriptions. From 91 pairs on scales <35 kpc/h, we detect only a slight excess in quasar clustering over our best-fit large-scale model. Integrated across all redshifts, the implied quasar bias is b_Q = 4.21+/-0.98 (b_Q = 3.93+/-0.71) at ~18 kpc/h (~28 kpc/h). Our best-fit (real-space) power index is ~-2 (i.e., $\xi(r) \propto r^{-2}$), implying steeper halo profiles than currently found in simulations. Alternatively, quasar binaries with separation <35 kpc/h may trace merging galaxies, with typical dynamical merger times t_d~(610+/-260)m^{-1/2} Myr/h, for quasars of host halo mass m x 10^{12} Msolar/h. We find UVX quasars at ~28 kpc/h cluster >5 times higher at z > 2, than at z < 2, at the $2.0\sigma$ level. However, as the space density of quasars declines as z increases, an excess of quasar binaries (over expectation) at z > 2 could be consistent with reduced merger rates at z > 2 for the galaxies forming UVX quasars. Comparing our clustering at ~28 kpc/h to a \xi(r)=(r/4.8\Mpch)^{-1.53} power-law, we find an upper limit on any excess of a factor of 4.3+/-1.3, which, noting some caveats, differs from large excesses recently measured for binary quasars, at $2.2\sigma$. We speculate that binary quasar surveys that are biased to z > 2 may find inflated clustering excesses when compared to models fit at z < 2. We provide details of 111 photometrically classified quasar pairs with separations <0.1'. Spectroscopy of these pairs could significantly constrain quasar dynamics in merging galaxies.Comment: 12pages, 3 figures, 2 tables; uses amulateapj; accepted to Ap

A New and Unusual Pathway for the Reaction of Neocarzinostatin Chromophore with Thiols. Revised Structure of the Protein-Directed Thiol Adduct

Neocarzinostatin (holo-NCS) is an antitumor antibiotic comprising a nonprotein chromophore component (1) and a 113- amino acid carrier protein (apo-NCS). Goldberg and coworkers first demonstrated that the reaction of the isolated chromophore (1) with thiols in the presence of double-stranded DNA leads to DNA cleavage by a free-radical mechanism. The pathway shown in Scheme 1 was later proposed to account for this activity, a proposal that is now supported by a considerable body of evidence. In 1992, Saito and co-workers showed that the reaction of holo-NCS with small thiols, such as β-mercaptoethanol (BME), takes a different course, to form a product that is formally a 1:1:1 adduct of thiol, 1, and water. Structure 2 was proposed for this adduct, along with the mechanistic pathway shown in Scheme 2. Complicating the analysis was the fact that 2 was an inseparable mixture of two components, present in equal parts

The potential impact of Ocean Thermal Energy Conversion (OTEC) on fisheries

The commercial development of ocean thermal energy conversion (OTEC) operations will involve some environmental perturbations for which there is no precedent experience. The pumping of very large volumes of warm surface water and cold deep water and its subsequent discharge will result in the impingement, entrainment, and redistribution of biota. Additional stresses to biota will be caused by biocide usage and temperature depressions. However, the artificial upwelling of nutrients associated with the pumping of cold deep water, and the artificial reef created by an OTEC plant may have positive effects on the local environment. Although more detailed information is needed to assess the net effect of an OTEC operation on fisheries, certain assumptions and calculations are made supporting the conclusion that the potential risk to fisheries is not significant enough to deter the early development of IDEe. It will be necessary to monitor a commercial-scale plant in order to remove many of the remaining uncertainties. (PDF file contains 39 pages.

The NGC 7129 Young Stellar Cluster: A Combined Spitzer, MMT, and 2MASS Census of Disks, Protostars, and Outflows

We present the analysis of seven band (1.2 to 8 micron) ground and space-based imaging of the NGC 7129 young stellar cluster from FLAMINGOS on MMT, 2MASS, and the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. An analysis of the H-[4.5] vs. J-H colors reveals 84 objects with circumstellar disks. Of these, 42 are located within the cluster core, a 0.5 pc (100'') radius region of enhanced stellar surface density. From a luminosity and extinction limited sample of the stars within the cluster core boundary we have determined that 54% +/- 14% have circumstellar disks. Finally, we report the detection of several resolved outflows in the IRAC 4.5 micron mosaic.Comment: 13 pages, 4 figures. Accepted to the Spitzer special issue of ApJS. The full-resolution preprint can be obtained from http://astro.pas.rochester.edu/~rguter/preprints/gutermuth_ngc7129_a.tar.g

Reverse undercompressive shock structures in driven thin film flow

We show experimental evidence of a new structure involving an undercompressive and reverse undercompressive shock for draining films driven by a surface tension gradient against gravity. The reverse undercompressive shock is unstable to transverse perturbations while the leading undercompressive shock is stable. Depending on the pinch-off film thickness, as controlled by the meniscus, either a trailing rarefaction wave or a compressive shock separates from the reverse undercompressive shock

A single nephron model of acute tubular injury: Role of tubuloglomerular feedback

A single nephron model of acute tubular injury: Role of tubuloglomerular feedback. A single nephron model of nephrotoxic tubular injury was established to examine the mechanism whereby acute tubular damage contributes to reductions in nephron filtration rate (SNGFR). Acute microperfusion of 0.5ng of uranyl nitrate (UN) into the early proximal tubule produced a significant reduction (16 to 30%) in SNGFR measured in both distal and proximal tubules of the same nephron and a decrease in absolute proximal reabsorption. Microperfused inulin was retained in the tubule suggesting this finding reflected a true reduction in SNGFR. Concurrent infusion of high dose furosemide (2 × 10-4M) and bumetanide (2 × 10-5M), but not low dose furosemide (2 × 10-5M), prevented the UN induced reduction in SNGFR. High dose furosemide begun after UN perfusion also prevented reduction in SNGFR. Continuous direct measurement of glomerular capillary hydrostatic pressure revealed no change. Distal intratubular Na+ and CI- concentration increased significantly after UN perfusion. Activation of tubuloglomerular feedback mechanisms best explains the reduction in glomerular ultrafiltration that is characteristic of nephrotoxic forms of tubular injury