699 research outputs found
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 and 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 PoissonâNernstâPlanck 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 ââidealââ 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. This research has been partially supported by the Cooperation Program between Polish scientific institutions and JINR (theme 04-5-1076-2009/2014, regulation number 62 of February 11, 2013).Apel, PY.; Ramirez Hoyos, P.; Blonskaya, IV.; Orelovitch, OL.; Sartowska, BA. (2014). Accurate characterization of single track-etched, conical nanopores. Physical Chemistry Chemical Physics. 16(29):15214-15223. https://doi.org/10.1039/c4cp01686fS15214152231629Bayley, H., & Martin, C. R. (2000). Resistive-Pulse SensingFrom Microbes to Molecules. Chemical Reviews, 100(7), 2575-2594. doi:10.1021/cr980099gDekker, C. (2007). Solid-state nanopores. Nature Nanotechnology, 2(4), 209-215. doi:10.1038/nnano.2007.27Healy, K., Schiedt, B., & Morrison, A. P. (2007). Solid-state nanopore technologies for nanopore-based DNA analysis. Nanomedicine, 2(6), 875-897. doi:10.2217/17435889.2.6.875Schoch, R. B., Han, J., & Renaud, P. (2008). Transport phenomena in nanofluidics. Reviews of Modern Physics, 80(3), 839-883. doi:10.1103/revmodphys.80.839Howorka, S., & Siwy, Z. (2009). Nanopore analytics: sensing of single molecules. Chemical Society Reviews, 38(8), 2360. doi:10.1039/b813796jWanunu, M. (2012). Nanopores: A journey towards DNA sequencing. Physics of Life Reviews, 9(2), 125-158. doi:10.1016/j.plrev.2012.05.010Stroeve, P., & Ileri, N. (2011). Biotechnical and other applications of nanoporous membranes. Trends in Biotechnology, 29(6), 259-266. doi:10.1016/j.tibtech.2011.02.002Cervera, J., Ramirez, P., Mafe, S., & Stroeve, P. (2011). Asymmetric nanopore rectification for ion pumping, electrical power generation, and information processing applications. Electrochimica Acta, 56(12), 4504-4511. doi:10.1016/j.electacta.2011.02.056Kocer, A., Tauk, L., & DĂ©jardin, P. (2012). Nanopore sensors: From hybrid to abiotic systems. Biosensors and Bioelectronics, 38(1), 1-10. doi:10.1016/j.bios.2012.05.013R. L. Fleischer , P. B.Price and R. M.Walker , Nuclear Tracks in Solids , University of California Press , Berkeley, CA , 1975Spohr, R. (2005). Status of ion track technologyâProspects of single tracks. Radiation Measurements, 40(2-6), 191-202. doi:10.1016/j.radmeas.2005.03.008Apel, P. Y., Korchev, Y. ., Siwy, Z., Spohr, R., & Yoshida, M. (2001). Diode-like single-ion track membrane prepared by electro-stopping. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 184(3), 337-346. doi:10.1016/s0168-583x(01)00722-4Siwy, Z., Gu, Y., Spohr, H. A., Baur, D., Wolf-Reber, A., Spohr, R., ⊠Korchev, Y. E. (2002). Rectification and voltage gating of ion currents in a nanofabricated pore. Europhysics Letters (EPL), 60(3), 349-355. doi:10.1209/epl/i2002-00271-3Mara, A., Siwy, Z., Trautmann, C., Wan, J., & Kamme, F. (2004). An Asymmetric Polymer Nanopore for Single Molecule Detection. Nano Letters, 4(3), 497-501. doi:10.1021/nl035141oSchiedt, B., Healy, K., Morrison, A. P., Neumann, R., & Siwy, Z. (2005). Transport of ions and biomolecules through single asymmetric nanopores in polymer films. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 236(1-4), 109-116. doi:10.1016/j.nimb.2005.03.265Cervera, J., Schiedt, B., Neumann, R., MafĂ©, S., & RamĂrez, P. (2006). Ionic conduction, rectification, and selectivity in single conical nanopores. The Journal of Chemical Physics, 124(10), 104706. doi:10.1063/1.2179797Siwy, Z. S., Powell, M. R., Petrov, A., Kalman, E., Trautmann, C., & Eisenberg, R. S. (2006). Calcium-Induced Voltage Gating in Single Conical Nanopores. Nano Letters, 6(8), 1729-1734. doi:10.1021/nl061114xChoi, Y., Baker, L. A., Hillebrenner, H., & Martin, C. R. (2006). Biosensing with conically shaped nanopores and nanotubes. Physical Chemistry Chemical Physics, 8(43), 4976. doi:10.1039/b607360cHarrell, C. C., Choi, Y., Horne, L. P., Baker, L. A., Siwy, Z. S., & Martin, C. R. (2006). Resistive-Pulse DNA Detection with a Conical Nanopore Sensorâ . Langmuir, 22(25), 10837-10843. doi:10.1021/la061234kWang, X., Xue, J., Wang, L., Guo, W., Zhang, W., Wang, Y., ⊠Ouyang, Q. (2007). How the geometric configuration and the surface charge distribution influence the ionic current rectification in nanopores. Journal of Physics D: Applied Physics, 40(22), 7077-7084. doi:10.1088/0022-3727/40/22/032Liu, Q., Wang, Y., Guo, W., Ji, H., Xue, J., & Ouyang, Q. (2007). Asymmetric properties of ion transport in a charged conical nanopore. Physical Review E, 75(5). doi:10.1103/physreve.75.051201Cervera, J., Alcaraz, A., Schiedt, B., Neumann, R., & RamĂrez, P. (2007). Asymmetric Selectivity of Synthetic Conical Nanopores Probed by Reversal Potential Measurements. The Journal of Physical Chemistry C, 111(33), 12265-12273. doi:10.1021/jp071884cWharton, J. E., Jin, P., Sexton, L. T., Horne, L. P., Sherrill, S. A., Mino, W. K., & Martin, C. R. (2007). A Method for Reproducibly Preparing Synthetic Nanopores for Resistive-Pulse Biosensors. Small, 3(8), 1424-1430. doi:10.1002/smll.200700106Vlassiouk, I., Smirnov, S., & Siwy, Z. (2008). Nanofluidic Ionic Diodes. Comparison of Analytical and Numerical Solutions. ACS Nano, 2(8), 1589-1602. doi:10.1021/nn800306uGuo, W., Xue, J. M., Zhang, W. M., Zou, X. Q., & Wang, Y. G. (2008). Electrolytic conduction properties of single conical nanopores. Radiation Measurements, 43, S623-S626. doi:10.1016/j.radmeas.2008.03.067KosiĆska, I. D., Goychuk, I., Kostur, M., Schmid, G., & HĂ€nggi, P. (2008). Rectification in synthetic conical nanopores: A one-dimensional Poisson-Nernst-Planck model. Physical Review E, 77(3). doi:10.1103/physreve.77.031131RamĂrez, P., Apel, P. Y., Cervera, J., & MafĂ©, S. (2008). Pore structure and function of synthetic nanopores with fixed charges: tip shape and rectification properties. 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., VacĂk, 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., MafĂ©, 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., LĂ©tant, 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. The Journal of Physical Chemistry C, 115(46), 22736-22741. doi:10.1021/jp2047344Zhang, B., Ai, Y., Liu, J., Joo, S. W., & Qian, S. (2011). Polarization Effect of a Dielectric Membrane on the Ionic Current Rectification in a Conical Nanopore. The Journal of Physical Chemistry C, 115(50), 24951-24959. doi:10.1021/jp2089388Apel, P. Y., Blonskaya, I. V., Orelovitch, O. L., Ramirez, P., & Sartowska, B. A. (2011). Effect of nanopore geometry on ion current rectification. Nanotechnology, 22(17), 175302. doi:10.1088/0957-4484/22/17/175302Pietschmann, J.-F., Wolfram, M.-T., Burger, M., Trautmann, C., Nguyen, G., Pevarnik, M., ⊠Siwy, Z. (2013). Rectification properties of conically shaped nanopores: consequences of miniaturization. Physical Chemistry Chemical Physics, 15(39), 16917. doi:10.1039/c3cp53105hGillespie, D., Boda, D., He, Y., Apel, P., & Siwy, Z. S. (2008). Synthetic Nanopores as a Test Case for Ion Channel Theories: The Anomalous Mole Fraction Effect without Single Filing. Biophysical Journal, 95(2), 609-619. doi:10.1529/biophysj.107.127985Kalman, E. B., Vlassiouk, I., & Siwy, Z. S. (2008). Nanofluidic Bipolar Transistors. Advanced Materials, 20(2), 293-297. doi:10.1002/adma.200701867Davenport, M., Rodriguez, A., Shea, K. J., & Siwy, Z. S. (2009). Squeezing Ionic Liquids through Nanopores. Nano Letters, 9(5), 2125-2128. doi:10.1021/nl900630zHou, X., Yang, F., Li, L., Song, Y., Jiang, L., & Zhu, D. (2010). A Biomimetic Asymmetric Responsive Single Nanochannel. Journal of the American Chemical Society, 132(33), 11736-11742. doi:10.1021/ja1045082Zhang, H., Tian, Y., & Jiang, L. (2013). From symmetric to asymmetric design of bio-inspired smart single nanochannels. Chemical Communications, 49(86), 10048. doi:10.1039/c3cc45526bApel, P. (2001). Track etching technique in membrane technology. Radiation Measurements, 34(1-6), 559-566. doi:10.1016/s1350-4487(01)00228-1Albrecht, D., Armbruster, P., Spohr, R., Roth, M., Schaupert, K., & Stuhrmann, H. (1985). Investigation of heavy ion produced defect structures in insulators by small angle scattering. Applied Physics A Solids and Surfaces, 37(1), 37-46. doi:10.1007/bf00617867Saleh, S. A., & Eyal, Y. (2005). Morphology of track cores and halos created by swift uranium ions in polycarbonate. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 236(1-4), 81-87. doi:10.1016/j.nimb.2005.03.258Apel, P. Y., Blonskaya, I. ., Oganessian, V. ., Orelovitch, O. ., & Trautmann, C. (2001). Morphology of latent and etched heavy ion tracks in radiation resistant polymers polyimide and poly(ethylene naphthalate). Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 185(1-4), 216-221. doi:10.1016/s0168-583x(01)00967-3Yu Apel, P., Blonskaya, I. V., Orelovitch, O. L., Sartowska, B. A., & Spohr, R. (2012). Asymmetric ion track nanopores for sensor technology. Reconstruction of pore profile from conductometric measurements. Nanotechnology, 23(22), 225503. doi:10.1088/0957-4484/23/22/225503J. F. Ziegler , J. P.Biersack and U.Littmark , The Stopping and Range of Ions in Solids , Pergamon , New York , 1985 , Free SRIM software is available from the website, http://www.srim.org/Apel, P. Y., Blonskaya, I. ., Didyk, A. Y., Dmitriev, S. ., Orelovitch, O. ., Root, D., ⊠Vutsadakis, V. . (2001). Surfactant-enhanced control of track-etch pore morphology. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 179(1), 55-62. doi:10.1016/s0168-583x(00)00691-1Ali, M., Ramirez, P., Nguyen, H. Q., Nasir, S., Cervera, J., Mafe, S., & Ensinger, W. (2012). Single Cigar-Shaped Nanopores Functionalized with Amphoteric Amino Acid Chains: Experimental and Theoretical Characterization. ACS Nano, 6(4), 3631-3640. doi:10.1021/nn3010119Ho, C., Qiao, R., Heng, J. B., Chatterjee, A., Timp, R. J., Aluru, N. R., & Timp, G. (2005). Electrolytic transport through a synthetic nanometer-diameter pore. Proceedings of the National Academy of Sciences, 102(30), 10445-10450. doi:10.1073/pnas.0500796102Nasir, S., Ramirez, P., Ali, M., Ahmed, I., Fruk, L., Mafe, S., & Ensinger, W. (2013). Nernst-Planck model of photo-triggered, pHâtunable ionic transport through nanopores functionalized with «caged» lysine chains. The Journal of Chemical Physics, 138(3), 034709. doi:10.1063/1.4775811Liebes, Y., Drozdov, M., Avital, Y. Y., Kauffmann, Y., Rapaport, H., Kaplan, W. D., & Ashkenasy, N. (2010). Reconstructing solid state nanopore shape from electrical measurements. Applied Physics Letters, 97(22), 223105. doi:10.1063/1.3521411Frament, C. M., & Dwyer, J. R. (2012). Conductance-Based Determination of Solid-State Nanopore Size and Shape: An Exploration of Performance Limits. The Journal of Physical Chemistry C, 116(44), 23315-23321. doi:10.1021/jp305381jFrament, C. M., Bandara, N., & Dwyer, J. R. (2013). Nanopore Surface Coating Delivers Nanopore Size and Shape through Conductance-Based Sizing. ACS Applied Materials & Interfaces, 5(19), 9330-9337. doi:10.1021/am402645
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
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