Emergent SU(3) symmetry in random spin-1 chains

We show that generic SU(2)-invariant random spin-1 chains have phases with an emergent SU(3) symmetry. We map out the full zero-temperature phase diagram and identify two different phases: (i) a conventional random singlet phase (RSP) of strongly bound spin pairs (SU(3) "mesons") and (ii) an unconventional RSP of bound SU(3) "baryons", which are formed, in the great majority, by spin trios located at random positions. The emergent SU(3) symmetry dictates that susceptibilities and correlation functions of both dipolar and quadrupolar spin operators have the same asymptotic behavior.Comment: 5 pages plus 3-page Supplemental Material, 5 figures; published versio

Emergent SU(N) symmetry in disordered SO(N) spin chains

Strongly disordered spin chains invariant under the SO(N) group are shown to display random-singlet phases with emergent SU(N) symmetry without fine tuning. The phases with emergent SU(N) symmetry are of two kinds: one has a ground state formed of randomly distributed singlets of strongly bound pairs of SO(N) spins (a `mesonic' phase), while the other has a ground state composed of singlets made out of strongly bound integer multiples of N SO(N) spins (a `baryonic' phase). The established mechanism is general and we put forward the cases of $\mathrm{N}=2,3,4$ and $6$ as prime candidates for experimental realizations in material compounds and cold-atoms systems. We display universal temperature scaling and critical exponents for susceptibilities distinguishing these phases and characterizing the enlarging of the microscopic symmetries at low energies.Comment: 5 pages, 2 figures, Contribution to the Topical Issue "Recent Advances in the Theory of Disordered Systems", edited by Ferenc Igl\'oi and Heiko Riege

Highly-symmetric random one-dimensional spin models

The interplay of disorder and interactions is a challenging topic of condensed matter physics, where correlations are crucial and exotic phases develop. In one spatial dimension, a particularly successful method to analyze such problems is the strong-disorder renormalization group (SDRG). This method, which is asymptotically exact in the limit of large disorder, has been successfully employed in the study of several phases of random magnetic chains. Here we develop an SDRG scheme capable to provide in-depth information on a large class of strongly disordered one-dimensional magnetic chains with a global invariance under a generic continuous group. Our methodology can be applied to any Lie-algebra valued spin Hamiltonian, in any representation. As examples, we focus on the physically relevant cases of SO(N) and Sp(N) magnetism, showing the existence of different randomness-dominated phases. These phases display emergent SU(N) symmetry at low energies and fall in two distinct classes, with meson-like or baryon-like characteristics. Our methodology is here explained in detail and helps to shed light on a general mechanism for symmetry emergence in disordered systems.Comment: 26 pages, 12 figure

Accurate characterization of single track-etched, conical nanopores

Single track-etched conical nanopores in polymer foils have attracted considerable attention in recent years due to their potential applications in biosensing, nanofluidics, information processing, and other fields. The performance of a nanopore critically depends on the size and shape of its narrowest, nanometer-sized region. In this paper, we reconstructed the profiles of both doubly-conical and conical pores, using an algorithm based on conductometric measurements performed in the course of etching, coupled with SEM data. We showed that pore constriction deviates from the conical shape, and the deviation depends on the energy loss of the particle that produced the track. Funnel-like profiles of tracks of four ions with different atomic numbers were derived from experimental data. The simulations, using a Poisson–Nernst–Planck model, demonstrated that the ion current rectification properties of the funnel-shaped asymmetrical pores significantly differ from those of conical ones if the tip radius of the pore is smaller than 10 nm. Upon subjecting to further etching, the pores gradually approach the ‘‘ideal’’ conical geometry, and the ion transport properties of these two pore configurations become almost indistinguishable.The authors are grateful to the Material Research group (GSI Darmstadt) for providing irradiated samples. The authors thank O. M. Ivanov for the irradiation of the polymer foils with accelerated ions. The help with SEM imaging provided by N. E. Lizunov is also appreciated. P. R. acknowledges financial support from the Generalitat Valenciana (project PROMETEO/GV/0069), Ministry of Science and Innovation of Spain, Materials Program (project MAT2012-32084), and FEDER. 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Nanotechnology, 19(31), 315707. doi:10.1088/0957-4484/19/31/315707Xia, F., Guo, W., Mao, Y., Hou, X., Xue, J., Xia, H., … Jiang, L. (2008). Gating of Single Synthetic Nanopores by Proton-Driven DNA Molecular Motors. Journal of the American Chemical Society, 130(26), 8345-8350. doi:10.1021/ja800266pAli, M., Bayer, V., Schiedt, B., Neumann, R., & Ensinger, W. (2008). Fabrication and functionalization of single asymmetric nanochannels for electrostatic/hydrophobic association of protein molecules. Nanotechnology, 19(48), 485711. doi:10.1088/0957-4484/19/48/485711Kovarik, M. L., Zhou, K., & Jacobson, S. C. (2009). Effect of Conical Nanopore Diameter on Ion Current Rectification. The Journal of Physical Chemistry B, 113(49), 15960-15966. doi:10.1021/jp9076189Fink, D., Vacík, J., Hnatowicz, V., Muñoz, G. H., Alfonta, L., & Klinkovich, I. (2010). Funnel-type etched ion tracks in polymers. Radiation Effects and Defects in Solids, 165(5), 343-361. doi:10.1080/10420151003743020Vlassiouk, I., Kozel, T. R., & Siwy, Z. S. (2009). Biosensing with Nanofluidic Diodes. Journal of the American Chemical Society, 131(23), 8211-8220. doi:10.1021/ja901120fKalman, E. B., Sudre, O., Vlassiouk, I., & Siwy, Z. S. (2008). Control of ionic transport through gated single conical nanopores. Analytical and Bioanalytical Chemistry, 394(2), 413-419. doi:10.1007/s00216-008-2545-3Ali, M., Ramirez, P., Mafé, S., Neumann, R., & Ensinger, W. (2009). A pH-Tunable Nanofluidic Diode with a Broad Range of Rectifying Properties. ACS Nano, 3(3), 603-608. doi:10.1021/nn900039fMukaibo, H., Horne, L. P., Park, D., & Martin, C. R. (2009). Controlling the Length of Conical Pores Etched in Ion-Tracked Poly(ethylene terephthalate) Membranes. Small, 5(21), 2474-2479. doi:10.1002/smll.200900810Sexton, L. T., Mukaibo, H., Katira, P., Hess, H., Sherrill, S. A., Horne, L. P., & Martin, C. R. (2010). An Adsorption-Based Model for Pulse Duration in Resistive-Pulse Protein Sensing. Journal of the American Chemical Society, 132(19), 6755-6763. doi:10.1021/ja100693xInnes, L., Powell, M. R., Vlassiouk, I., Martens, C., & Siwy, Z. S. (2010). Precipitation-Induced Voltage-Dependent Ion Current Fluctuations in Conical Nanopores. The Journal of Physical Chemistry C, 114(18), 8126-8134. doi:10.1021/jp910815pKubeil, C., & Bund, A. (2011). The Role of Nanopore Geometry for the Rectification of Ionic Currents. The Journal of Physical Chemistry C, 115(16), 7866-7873. doi:10.1021/jp111377hPowell, M. R., Sa, N., Davenport, M., Healy, K., Vlassiouk, I., Létant, S. E., … Siwy, Z. S. (2011). Noise Properties of Rectifying Nanopores. The Journal of Physical Chemistry C, 115(17), 8775-8783. doi:10.1021/jp2016038Wang, L., Sun, L., Wang, C., Chen, L., Cao, L., Hu, G., … Wang, Y. (2011). Nanofluidic Pulser Based on Polymer Conical Nanopores. 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Barred Galaxies in the Coma Cluster

We use ACS data from the HST Treasury survey of the Coma cluster (z~0.02) to study the properties of barred galaxies in the Coma core, the densest environment in the nearby Universe. This study provides a complementary data point for studies of barred galaxies as a function of redshift and environment. From ~470 cluster members brighter than M_I = -11 mag, we select a sample of 46 disk galaxies (S0--Im) based on visual classification. The sample is dominated by S0s for which we find an optical bar fraction of 47+/-11% through ellipse fitting and visual inspection. Among the bars in the core of the Coma cluster, we do not find any very large (a_bar > 2 kpc) bars. Comparison to other studies reveals that while the optical bar fraction for S0s shows only a modest variation across low-to-intermediate density environments (field to intermediate-density clusters), it can be higher by up to a factor of ~2 in the very high-density environment of the rich Coma cluster core.Comment: Proceedings of the Bash symposium, to appear in the Astronomical Society of the Pacific Conference Series, eds. L. Stanford, L. Hao, Y. Mao, J. Gree

Molecular detection of Eastern Equine Encephalitis virus in mosquitoes from La Pintada (Antioquia)

ABSTRACT Objective. The detection of emerging and re-emerging arboviruses in mosquitoes from urban and rural areas, is fundamental for predict possible epidemic outbreaks in human populations. The Municipality of La Pintada (Antioquia), is characterized by the presence of dry tropical forest relicts, fishing, tourism, farms and mining. An entomological research was performed for explore the possible circulation of arboviruses of public health importance. Materials and methods. Mosquitoes were captured in urban and rural sites in February-April of 2012. The specimens were stored in liquid nitrogens tanks and were grouped using taxonomic keys for genera. RNA extraction from pools and generic/nested RT-PCR was performed for Flavivirus, Alphavirus, Orthobunyavirus (Group Bunyamwera) and Phlebovirus. Results. 1274 mosquitoes were collected, mainly belonging to Culex and Aedes genera. RNA extracts of 64 pools were tested by RT-PCR and one pool was positive for Alphavirus. Sequencing of the RT- PCR product and the analysis with sequences storage in GenBank designate the presence of Eastern equine encephalitis virus (EEEV). Conclusions. This is the first record of natural infection from EEEV in mosquitoes from La Pintada (Antioquia), an area with ecological elements that favor the emergence of emerging and re-emerging arboviruses of medical and veterinarian importance

Parity-Violating Hydrodynamics in 2+1 Dimensions

We study relativistic hydrodynamics of normal fluids in two spatial dimensions. When the microscopic theory breaks parity, extra transport coefficients appear in the hydrodynamic regime, including the Hall viscosity, and the anomalous Hall conductivity. In this work we classify all the transport coefficients in first order hydrodynamics. We then use properties of response functions and the positivity of entropy production to restrict the possible coefficients in the constitutive relations. All the parity-breaking transport coefficients are dissipationless, and some of them are related to the thermodynamic response to an external magnetic field and to vorticity. In addition, we give a holographic example of a strongly interacting relativistic fluid where the parity-violating transport coefficients are computable.Comment: 39+1 page

Chiral drag force

We provide a holographic evaluation of novel contributions to the drag force acting on a heavy quark moving through strongly interacting plasma. The new contributions are chiral in that they act in opposite directions in plasmas containing an excess of left- or right-handed quarks and in that they are proportional to the coefficient of the axial anomaly. These new contributions to the drag force act either parallel to or antiparallel to an external magnetic field or to the vorticity of the fluid plasma. In all these respects, these contributions to the drag force felt by a heavy quark are analogous to the chiral magnetic effect on light quarks. However, the new contribution to the drag force is independent of the electric charge of the heavy quark and is the same for heavy quarks and antiquarks. We show that although the chiral drag force can be non-vanishing for heavy quarks that are at rest in the local fluid rest frame, it does vanish for heavy quarks that are at rest in a suitably chosen frame. In this frame, the heavy quark at rest sees counterpropagating momentum and charge currents, both proportional to the axial anomaly coefficient, but feels no drag force. This provides strong concrete evidence for the absence of dissipation in chiral transport, something that has been predicted previously via consideration of symmetries. Along the way to our principal results, we provide a general calculation of the corrections to the drag force due to the presence of gradients in the flowing fluid in the presence of a nonzero chemical potential. We close with a consequence of our result that is at least in principle observable in heavy ion collisions, namely an anticorrelation between the direction of the CME current for light quarks in a given event and the direction of the kick given to the momentum of all the heavy quarks and antiquarks in that event.Comment: 28 pages, small improvement to the discussion of gravitational anomaly, references adde

Bortezomib sensitizes non-small cell lung cancer to mesenchymal stromal cell-delivered inducible caspase-9-mediated cytotoxicity

Delivery of suicide genes to solid tumors represents a promising tumor therapy strategy. However, slow or limited killing by suicide genes and ineffective targeting of the tumor has reduced effectiveness. We have adapted a suicide system based on an inducible caspase-9 (iC9) protein that is activated using a specific chemical inducer of dimerization (CID) for adenoviral-based delivery to lung tumors via mesenchymal stromal cells (MSCs). Four independent human non-small cell lung cancer (NSCLC) cell lines were transduced with adenovirus encoding iC9, and all underwent apoptosis when iC9 was activated by adding CID. However, there was a large variation in the percentage of cell killing induced by CID across the different lines. The least responsive cell lines were sensitized to apoptosis by combined inhibition of the proteasome using bortezomib. These results were extended to an in vivo model using human NSCLC xenografts. E1A-expressing MSCs replicated Ad.iC9 and delivered the virus to lung tumors in SCID mice. Treatment with CID resulted in some reduction of tumor growth, but addition of bortezomib led to greater reduction of tumor size. The enhanced apoptosis and anti-tumor effect of combining MSC-delivered Ad.iC9, CID and bortezomib appears to be due to increased stabilization of active caspase-3, as proteasomal inhibition increased the levels of cleaved caspase-9 and caspase-3. Knockdown of X-linked inhibitor of apoptosis protein (XIAP), a caspase inhibitor that targets active caspase-3 to the proteasome, also sensitized iC9-transduced cells to CID, suggesting that blocking the proteasome counteracts XIAP to permit apoptosis. Thus, MSC-based delivery of the iC9 suicide gene to human NSCLC effectively targets lung cancer cells for elimination. Combining this therapy with bortezomib, a drug that is otherwise inactive in this disease, further enhances the anti-tumor activity of this strategy