Experimental analysis of passive intermodulation at waveguide flange bolted connections

[EN] In this paper, the generation of passive intermodulation at rectangular waveguide flange bolted connections is investigated. An exhaustive series of tests has been performed in order to provide understanding on the physics lying behind such a phenomenon. In particular, the intermodulation response of the system has been studied as a function of the applied torque to the flange screws. It has been found that, in some situations, the intermodulation response differs from its expected behavior. An interpretation of such discrepancies is given, and practical guidelines for the design of waveguide flanges free of passive intermodulation are provided as well.This work was supported by the European Space Agency under the Surface Treatment and Coating for the Reduction of Multipactor and Passive Intermodulation Effects in RF Components Project, by the European Space Research and Technology Centre under Contract 17025/03/NL/EC, by the Generalitat Valenciana (Spain) under PREDECTOR Project IIARC0/2004/020, and by the Spanish Government (MEC) under a Juan de la Cierva Program Fellowship.Vicente, C.; Wolk, D.; Hartnagel, H.; Gimeno, B.; Boria Esbert, VE.; Raboso, D. (2007). Experimental analysis of passive intermodulation at waveguide flange bolted connections. IEEE Transactions on Microwave Theory and Techniques. 55(5):1018-1028. https://doi.org/10.1109/TMTT.2007.895400S1018102855

Novel types of anti-ecloud surfaces

In high power RF devices for space, secondary electron emission appears as the main parameter governing the multipactor effect and as well as the e-cloud in large accelerators. Critical experimental activities included development of coatings with low secondary electron emission yield (SEY) for steel (large accelerators) and aluminium (space applications). Coatings with surface roughness of high aspect ratio producing the so-call secondary emission suppression effect appear as the selected strategy. In this work a detailed study of the SEY of these technological coatings and also the experimental deposition methods (PVD and electrochemical) are presented. The coating-design approach selected for new low SEY coatings include rough metals (Ag, Au, Al), rough alloys (NEG), particulated and magnetized surfaces, and also graphene like coatings. It was found that surface roughness also mitigate the SEY deterioration due to aging processes.Comment: 4 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba, Italy; CERN Yellow Report CERN-2013-002, pp.153-15

Nonstationary statistical theory for multipactor

[EN] This work presents a new and general approach to the real dynamics of the multipactor process: the nonstationary statistical multipactor theory. The nonstationary theory removes the stationarity assumption of the classical theory and, as a consequence, it is able to adequately model electron exponential growth as well as absorption processes, above and below the multipactor breakdown level. In addition, it considers both double-surface and single-surface interactions constituting a full framework for nonresonant polyphase multipactor analysis. This work formulates the new theory and validates it with numerical and experimental results with excellent agreement. (C) 2010 American Institute of Physics.The authors would like to thank ESA/ESTEC for having funded this research activity through the Contract "Study of High Order Modes and Fringing Fields in Multipactor Effect" (Contract No. 1-5918/08/NL/GLC) and to the Ministerio de Ciencia e Innovacion (Spain) for the support through the "Programa Torres Quevedo" Contract No. PTQ05-02-02759.Anza, S.; Vicente, C.; Gil, J.; Boria Esbert, VE.; Gimeno, B.; Raboso, D. (2010). Nonstationary statistical theory for multipactor. Physics of Plasmas. 17(6):1-11. https://doi.org/10.1063/1.3443128S111176Farnsworth, P. T. (1934). Television by electron image scanning. Journal of the Franklin Institute, 218(4), 411-444. doi:10.1016/s0016-0032(34)90415-4Starting potentials of high-frequency gas discharges at low pressure. (1948). Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 192(1030), 446-463. doi:10.1098/rspa.1948.0018Vaughan, J. R. M. (1988). Multipactor. IEEE Transactions on Electron Devices, 35(7), 1172-1180. doi:10.1109/16.3387Hatch, A. J., & Williams, H. B. (1954). The Secondary Electron Resonance Mechanism of Low‐Pressure High‐Frequency Gas Breakdown. Journal of Applied Physics, 25(4), 417-423. doi:10.1063/1.1721656Hatch, A. J., & Williams, H. B. (1958). Multipacting Modes of High-Frequency Gaseous Breakdown. Physical Review, 112(3), 681-685. doi:10.1103/physrev.112.681H. M. Wachowski, El Segundo Technical Operations Aerospace Corporation, Technical Report No. TDR-269(9990)-5, El Segundo, California, 1964.Furman, M., & Pivi, M. (2002). Probabilistic model for the simulation of secondary electron emission. Physical Review Special Topics - Accelerators and Beams, 5(12). doi:10.1103/physrevstab.5.124404A. Woode and J. Petit, ESTEC Technical Report No. 1556, Noordwijk, 1989.Riyopoulos, S., Chernin, D., & Dialetis, D. (1995). Theory of electron multipactor in crossed fields. Physics of Plasmas, 2(8), 3194-3213. doi:10.1063/1.871151Kishek, R. A., Lau, Y. Y., Ang, L. K., Valfells, A., & Gilgenbach, R. M. (1998). Multipactor discharge on metals and dielectrics: Historical review and recent theories. Physics of Plasmas, 5(5), 2120-2126. doi:10.1063/1.872883Gilardini, A. L. (1992). New breakdown modes of the multipacting discharge. Journal of Applied Physics, 71(9), 4629-4631. doi:10.1063/1.350767Kryazhev, A., Buyanova, M., Semenov, V., Anderson, D., Lisak, M., Puech, J., … Sombrin, J. (2002). Hybrid resonant modes of two-sided multipactor and transition to the polyphase regime. Physics of Plasmas, 9(11), 4736-4743. doi:10.1063/1.1514969Semenov, V. E., Rakova, E., Udiljak, R., Anderson, D., Lisak, M., & Puech, J. (2008). Conformal mapping analysis of multipactor breakdown in waveguide irises. Physics of Plasmas, 15(3), 033501. doi:10.1063/1.2884712Semenov, V. E., Rakova, E. I., Anderson, D., Lisak, M., & Puech, J. (2007). Multipactor in rectangular waveguides. Physics of Plasmas, 14(3), 033501. doi:10.1063/1.2480678Woo, R. (1968). Multipacting Discharges between Coaxial Electrodes. Journal of Applied Physics, 39(3), 1528-1533. doi:10.1063/1.1656390Vdovicheva, N. K., Sazontov, A. G., & Semenov, V. E. (2004). Statistical Theory of Two-Sided Multipactor. Radiophysics and Quantum Electronics, 47(8), 580-596. doi:10.1023/b:raqe.0000049556.18329.e9Vdovicheva, N. K., Sazontov, A. G., Sazontov, V. A., & Semenov, V. E. (2006). Influence of the angular anisotropy of secondary emission on the characteristics of a two-sided multipactor. Radiophysics and Quantum Electronics, 49(5), 368-376. doi:10.1007/s11141-006-0069-2Sazontov, A. G., Sazontov, V. A., & Vdovicheva, N. K. (2008). Multipactor Breakdown Prediction in a Rectangular Waveguide: Statistical Theory and Simulation Results. Contributions to Plasma Physics, 48(4), 331-346. doi:10.1002/ctpp.200810057Sazontov, A., Buyanova, M., Semenov, V., Rakova, E., Vdovicheva, N., Anderson, D., … Lapierre, L. (2005). Effect of emission velocity spread of secondary electrons in two-sided multipactor. Physics of Plasmas, 12(5), 053102. doi:10.1063/1.1881532Kossyi, I. A., Lukyanchikov, G. S., Semenov, V. E., Rakova, E. I., Anderson, D., Lisak, M., & Puech, J. (2008). Polyphase (non-resonant) multipactor in rectangular waveguides. Journal of Physics D: Applied Physics, 41(6), 065203. doi:10.1088/0022-3727/41/6/065203Vaughan, J. R. M. (1989). A new formula for secondary emission yield. IEEE Transactions on Electron Devices, 36(9), 1963-1967. doi:10.1109/16.34278C. Vicente, M. Mattes, D. Wolk, H. L. Hartnagel, J. R. Mosig, and D. Raboso, Proceedings of the 5th International Workshop on Multipactor, RF and DC Corona and Passive Intermodulation in Space RF Hardware (ESTEC, Noordwijk, The Netherlands, 2005), pp. 11–17.Gilardini, A. L. (1995). Multipacting discharges: Constant‐ktheory and simulation results. Journal of Applied Physics, 78(2), 783-795. doi:10.1063/1.360336A. Kryazhev, M.S. thesis, Chalmers University of Technology, Göteborg, Sweden, 2002.Anza, S., Vicente, C., Gimeno, B., Boria, V. E., & Armendáriz, J. (2007). Long-term multipactor discharge in multicarrier systems. Physics of Plasmas, 14(8), 082112. doi:10.1063/1.2768019P. Zuccarello, A. González, G. Piñero, and M. de Diego, Proceedings of the 4th International Workshop on Multipactor, RF and DC Corona and Passive Intermodulation in Space RF Hardware (ESTEC, Noordwijk, The Netherlands, 2003), pp. 469–473.Polyanin, A. (1998). Handbook of Integral Equations. doi:10.1201/9781420050066S. Anza, C. Vicente, D. Raboso, J. Gil, B. Gimeno, and V. E. Boria, IEEE International Microwave Symposium (IEEE, Atlanta, 2008), pp. 1095–1098.C. Vicente, M. Mattes, D. Wolk, H. L. Hartnagel, J. R. Mosig, and D. Raboso, Microwave Symposium Digest, IEEE MTT-S International (IEEE, Long Beach, California, 2005), Vol. 2, pp. 1055–1058

A Novel Technique for Mitigating Multipactor by Means of Magnetic Surface Roughness

Multipactor phenomena which are closely linked to the SEY (secondary electron yield)can be mitigated by many different methods including groves in the metal surface as well as using electric or magnetic bias fields. However frequently the application of global magnetic or electric bias field is not practicable considering the weight and power limitations on-board satellites. Additionally, surface grooves may degrade the RF performance. Here we present a novel technique which is based on a magnetostatic field pattern on the metallic surface with fast spatial modulation in the order of 30 micron. This field pattern is produced by proper magnetization of an underlying ferromagnetic layer such as nickel. Simulations and preliminary experimental results will be shown and a number of applications, both for particle accelerators and satellite microwave payloads are discussed

AO-4025 ITT ESA - Surface treatments and coatings for reduction of multipactor and Passive InterModulation (PIM) effect in RF components

This is the electronic version of a paper presented at the 4th International Workshop on Multipactor, Corona and Passive Intermodulation in Space RF Hardware (MULCOPIM 2003) held in Noordwijk, The Netherlands.ESA has initiated several activities with the aim to reduce the risk of multipaction and corona effects in space hardware. Within the activity Surface Treatment and Coating for the Reduction of Multipactor and Passive Intermodulation (PIM) Effects in RF Components a European group has been formed to investigate new surface coatings / treatments to improve the power handling capability of passive equipment with respect to multipactor and passive intermodulation. This paper presents an overview of the activities to be performed within this project and describes the first results

Multipactor radiation analysis within a waveguide region based on a frequency-domain representation of the dynamics of charged particles

[EN] A technique for the accurate computation of the electromagnetic fields radiated by a charged particle moving within a parallel-plate waveguide is presented. Based on a transformation of the time-varying current density of the particle into a time-harmonic current density, this technique allows the evaluation of the radiated electromagnetic fields both in the frequency and time domains, as well as in the near- and far-field regions. For this purpose, several accelerated versions of the parallel-plate Green's function in the frequency domain have been considered. The theory has been successfully applied to the multipactor discharge occurring within a two metal-plates region. The proposed formulation has been tested with a particle-in-cell code based on the finite-difference time-domain method, obtaining good agreement.The authors would like to thank ESA/ESTEC for having funded this research activity through the Contract "RF Breakdown in Multicarrier Systems" (Contract No. 19918/06/NL/GLC).Gimeno, B.; Sorolla, E.; Anza, S.; Vicente, C.; Gil, J.; Pérez, AM.; Boria Esbert, VE.... (2009). Multipactor radiation analysis within a waveguide region based on a frequency-domain representation of the dynamics of charged particles. Physical review. E, Statistical, nonlinear, and soft matter physics. 79(4):1-9. https://doi.org/10.1103/PhysRevE.79.046604S19794Figueroa, H., Gai, W., Konecny, R., Norem, J., Ruggiero, A., Schoessow, P., & Simpson, J. (1988). Direct Measurement of Beam-Induced Fields in Accelerating Structures. Physical Review Letters, 60(21), 2144-2147. doi:10.1103/physrevlett.60.2144Ng, K.-Y. (1990). Wake fields in a dielectric-lined waveguide. Physical Review D, 42(5), 1819-1828. doi:10.1103/physrevd.42.1819Rosing, M., & Gai, W. (1990). Longitudinal- and transverse-wake-field effects in dielectric structures. Physical Review D, 42(5), 1829-1834. doi:10.1103/physrevd.42.1829Gai, W., Kanareykin, A. D., Kustov, A. L., & Simpson, J. (1997). Numerical simulations of intense charged-particle beam propagation in a dielectric wake-field accelerator. Physical Review E, 55(3), 3481-3488. doi:10.1103/physreve.55.3481Burov, A., & Danilov, V. (1999). Suppression of Transverse Bunch Instabilities by Asymmetries in the Chamber Geometry. Physical Review Letters, 82(11), 2286-2289. doi:10.1103/physrevlett.82.2286Xiao, L., Gai, W., & Sun, X. (2001). Field analysis of a dielectric-loaded rectangular waveguide accelerating structure. Physical Review E, 65(1). doi:10.1103/physreve.65.016505Jing, C., Liu, W., Xiao, L., Gai, W., Schoessow, P., & Wong, T. (2003). Dipole-mode wakefields in dielectric-loaded rectangular waveguide accelerating structures. Physical Review E, 68(1). doi:10.1103/physreve.68.016502Stupakov, G., Bane, K. L. F., & Zagorodnov, I. (2007). Optical approximation in the theory of geometric impedance. Physical Review Special Topics - Accelerators and Beams, 10(5). doi:10.1103/physrevstab.10.054401Hatch, A. J., & Williams, H. B. (1954). The Secondary Electron Resonance Mechanism of Low‐Pressure High‐Frequency Gas Breakdown. Journal of Applied Physics, 25(4), 417-423. doi:10.1063/1.1721656Hatch, A. J., & Williams, H. B. (1958). Multipacting Modes of High-Frequency Gaseous Breakdown. Physical Review, 112(3), 681-685. doi:10.1103/physrev.112.681Vaughan, J. R. M. (1988). Multipactor. IEEE Transactions on Electron Devices, 35(7), 1172-1180. doi:10.1109/16.3387Gilardini, A. L. (1995). Multipacting discharges: Constant‐ktheory and simulation results. Journal of Applied Physics, 78(2), 783-795. doi:10.1063/1.360336Riyopoulos, S. (1997). Multipactor saturation due to space-charge-induced debunching. Physics of Plasmas, 4(5), 1448-1462. doi:10.1063/1.872319Kryazhev, A., Buyanova, M., Semenov, V., Anderson, D., Lisak, M., Puech, J., … Sombrin, J. (2002). Hybrid resonant modes of two-sided multipactor and transition to the polyphase regime. Physics of Plasmas, 9(11), 4736-4743. doi:10.1063/1.1514969Udiljak, R., Anderson, D., Ingvarson, P., Jordan, U., Jostell, U., Lapierre, L., … Sombrin, J. (2003). New method for detection of multipaction. IEEE Transactions on Plasma Science, 31(3), 396-404. doi:10.1109/tps.2003.811646De Lara, J., Perez, F., Alfonseca, M., Galan, L., Montero, I., Roman, E., & Garcia-Baquero, D. R. (2006). Multipactor prediction for on-board spacecraft RF equipment with the MEST software tool. IEEE Transactions on Plasma Science, 34(2), 476-484. doi:10.1109/tps.2006.872450Torregrosa, G., Coves, A., Vicente, C. P., Perez, A. M., Gimeno, B., & Boria, V. E. (2006). Time evolution of an electron discharge in a parallel-plate dielectric-loaded waveguide. IEEE Electron Device Letters, 27(7), 619-621. doi:10.1109/led.2006.877284Udiljak, R., Anderson, D., Lisak, M., Semenov, V. E., & Puech, J. (2007). Multipactor in a coaxial transmission line. I. Analytical study. Physics of Plasmas, 14(3), 033508. doi:10.1063/1.2710464Semenov, V. E., Zharova, N., Udiljak, R., Anderson, D., Lisak, M., & Puech, J. (2007). Multipactor in a coaxial transmission line. II. Particle-in-cell simulations. Physics of Plasmas, 14(3), 033509. doi:10.1063/1.2710466Anza, S., Vicente, C., Gimeno, B., Boria, V. E., & Armendáriz, J. (2007). Long-term multipactor discharge in multicarrier systems. Physics of Plasmas, 14(8), 082112. doi:10.1063/1.2768019Udiljak, R., Anderson, D., Lisak, M., Puech, J., & Semenov, V. E. (2007). Multipactor in a Waveguide Iris. IEEE Transactions on Plasma Science, 35(2), 388-395. doi:10.1109/tps.2007.892737Burton, R. J., de Jong, M. S., & Funk, L. W. (1991). Vacuum and multipactor performance of the hadron electron ring accelerator 52 MHz cavities. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 9(3), 2081-2084. doi:10.1116/1.577417Yamaguchi, S., Saito, Y., Anami, S., & Michizono, S. (1992). Trajectory simulation of multipactoring electrons in an S-band pillbox RF window. IEEE Transactions on Nuclear Science, 39(2), 278-282. doi:10.1109/23.277497Kishek, R., & Lau, Y. Y. (1995). Interaction of Multipactor Discharge and rf Circuit. Physical Review Letters, 75(6), 1218-1221. doi:10.1103/physrevlett.75.1218Lay-Kee Ang, Lau, Y. Y., Kishek, R. A., & Gilgenbach, R. M. (1998). Power deposited on a dielectric by multipactor. IEEE Transactions on Plasma Science, 26(3), 290-295. doi:10.1109/27.700756Kishek, R. A., Lau, Y. Y., Ang, L. K., Valfells, A., & Gilgenbach, R. M. (1998). Multipactor discharge on metals and dielectrics: Historical review and recent theories. Physics of Plasmas, 5(5), 2120-2126. doi:10.1063/1.872883Neuber, A., Hemmert, D., Krompholz, H., Hatfield, L., & Kristiansen, M. (1999). Initiation of high power microwave dielectric interface breakdown. Journal of Applied Physics, 86(3), 1724-1728. doi:10.1063/1.370953Chojnacki, E. (2000). Simulations of a multipactor-inhibited waveguide geometry. Physical Review Special Topics - Accelerators and Beams, 3(3). doi:10.1103/physrevstab.3.032001Cimino, R., Collins, I. R., Furman, M. A., Pivi, M., Ruggiero, F., Rumolo, G., & Zimmermann, F. (2004). Can Low-Energy Electrons Affect High-Energy Physics Accelerators? Physical Review Letters, 93(1). doi:10.1103/physrevlett.93.014801Abe, T., Kageyama, T., Akai, K., Ebihara, K., Sakai, H., & Takeuchi, Y. (2006). Multipactoring zone map of an rf input coupler and its application to high beam current storage rings. Physical Review Special Topics - Accelerators and Beams, 9(6). doi:10.1103/physrevstab.9.062002Sorolla, E., Anza, S., Gimeno, B., Perez, A. M. P., Vicente, C., Gil, J., … Boria, V. E. (2008). An Analytical Model to Evaluate the Radiated Power Spectrum of a Multipactor Discharge in a Parallel-Plate Region. IEEE Transactions on Electron Devices, 55(8), 2252-2258. doi:10.1109/ted.2008.926271Harrington, R. F. (2001). Time-Harmonic Electromagnetic Fields. doi:10.1109/9780470546710Hanson, G. W., & Yakovlev, A. B. (2002). Operator Theory for Electromagnetics. doi:10.1007/978-1-4757-3679-3Ewald, P. P. (1921). Die Berechnung optischer und elektrostatischer Gitterpotentiale. Annalen der Physik, 369(3), 253-287. doi:10.1002/andp.19213690304Myun-Joo Park, & Sangwook Nam. (1998). Rapid summation of the Green’s function for the rectangular waveguide. IEEE Transactions on Microwave Theory and Techniques, 46(12), 2164-2166. doi:10.1109/22.739301Capolino, F., Wilton, D. R., & Johnson, W. A. (2005). Efficient computation of the 2-D Green’s function for 1-D periodic structures using the Ewald method. IEEE Transactions on Antennas and Propagation, 53(9), 2977-2984. doi:10.1109/tap.2005.854556Kustepeli, A., & Martin, A. Q. (2000). On the splitting parameter in the Ewald method. IEEE Microwave and Guided Wave Letters, 10(5), 168-170. doi:10.1109/75.85036

Conditional expression of HGAL leads to the development of diffuse large B-cell lymphoma in mice

Diffuse large B-cell lymphomas (DLBCLs) are clinically and genetically heterogeneous tumors. Deregulation of diverse biological processes specific to B cells, such as B-cell receptor (BCR) signaling and motility regulation, contribute to lymphomagenesis. Human germinal center associated lymphoma (HGAL) is a B-cell–specific adaptor protein controlling BCR signaling and B lymphocyte motility. In normal B cells, it is expressed in germinal center (GC) B lymphocytes and promptly downregulated upon further differentiation. The majority of DLBCL tumors, primarily GC B-cell types, but also activated types, express HGAL. To investigate the consequences of constitutive expression of HGAL in vivo, we generated mice that conditionally express human HGAL at different stages of hematopoietic development using 3 restricted Cre-mediated approaches to initiate expression of HGAL in hematopoietic stem cells, pro-B cells, or GC B cells. Following immune stimulation, we observed larger GCs in mice in which HGAL expression was initiated in GC B cells. All 3 mouse strains developed DLBCL at a frequency of 12% to 30% starting at age 13 months, leading to shorter survival. Immunohistochemical studies showed that all analyzed tumors were of the GC B-cell type. Exon sequencing revealed mutations reported in human DLBCL. Our data demonstrate that constitutive enforced expression of HGAL leads to DLBCL development

Analysis of the electromagnetic radiation generated by a multipactor discharge occurring within a microwave passive component

International audienceMultipactoring is a non-linear phenomenon that appears in highpower microwave equipments operating under vacuum conditions and causes several undesirable effects. In this manuscript, a theoretical and experimental study of the RF spectrum radiated by a multipactor discharge, occurring within a realistic microwave component based on rectangular waveguides, is reported. The electromagnetic coupling of a multipactor current to the fundamental propagative mode of a uniform waveguide has been analyzed in the context of the microwave network theory. The discharge produced under a single-carrier RF voltage regime has been approached as a shunt current source exciting such a mode in a transmission-line gap-region. By means of a simple equivalent circuit, this model allows predicting the harmonics generated by the discharge occurring in a realistic passive waveguide component. Power spectrum radiated by a third order multipactor discharge has been measured in an E-plane silver-plated waveguide transformer, thus validating qualitatively the presented theory to simulate the noise generated by a single-carrier multipactor discharge

Inhibition of inflammatory signaling in Pax5 mutant cells mitigates B-cell leukemogenesis

Altres ajuts: We would like to thank the "Fundación Ramón Areces," a Research Contract with the "Fundación Síndrome de Wolf-Hirschhorn o 4p-", and institutional grants from the "Fundación Ramón Areces" and "Banco de Santander" to the CBMSO. Research in the ISG group is partially supported by by Junta de Castilla y León (UIC-017, CSI001U16, and CSI234P18), and by the German Jose Carreras Foundation (DJCLS R13/26; DJCLS 07R/2019). AC-G and M.I.-H. are supported by FSE-Conserjería de Educación de la Junta de Castilla y León 2019 and 2020 (ESF- European Social Fund) fellowship, respectively. J.R.-G. is supported by a scholarship from University of Salamanca co-financed by Banco Santander and ESF.PAX5 is one of the most frequently mutated genes in B-cell acute lymphoblastic leukemia (B-ALL), and children with inherited preleukemic PAX5 mutations are at a higher risk of developing the disease. Abnormal profiles of inflammatory markers have been detected in neonatal blood spot samples of children who later developed B-ALL. However, how inflammatory signals contribute to B-ALL development is unclear. Here, we demonstrate that Pax5 heterozygosis, in the presence of infections, results in the enhanced production of the inflammatory cytokine interleukin-6 (IL-6), which appears to act in an autocrine fashion to promote leukemia growth. Furthermore, in vivo genetic downregulation of IL-6 in these Pax5 heterozygous mice retards B-cell leukemogenesis, and in vivo pharmacologic inhibition of IL-6 with a neutralizing antibody in Pax5 mutant mice with B-ALL clears leukemic cells. Additionally, this novel IL-6 signaling paradigm identified in mice was also substantiated in humans. Altogether, our studies establish aberrant IL6 expression caused by Pax5 loss as a hallmark of Pax5-dependent B-ALL and the IL6 as a therapeutic vulnerability for B-ALL characterized by PAX5 loss

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns