44 research outputs found
Chemical vapour deposition of tungsten by H2 reduction of WCl6. Fourth European workshop on refractory metals and silicides: Selected papers, Saltsjobaden, Sweden, March 24-27, 1991
No full textThermoelastic dissipation in inhomogeneous media: loss measurements and displacement noise in coated test masses for interferometric gravitational wave detectors
No full textThe displacement noise in the test-mass mirrors of interferometric gravitational wave detectors is proportional to their elastic dissipation at the observation frequencies. In this paper, we analyze one fundamental source of dissipation in thin coatings, thermoelastic damping associated with the dissimilar thermal and elastic properties of the film and the substrate. We obtain expressions for the thermoelastic dissipation factor necessary to interpret resonant loss measurements, and for the spectral density of displacement noise imposed on a Gaussian beam reflected from the face of a coated mass. The predicted size of these effects is large enough to affect the interpretation of loss measurements, and to influence design choices in advanced gravitational wave detectors
The intrinsic mechanical loss factor of hydroxy-catalysis bonds for use in the mirror suspensions of gravitational wave detectors
No full textThis paper describes investigations into the mechanical losses of bonds created by hydroxy-catalysis bonding. Evaluation of the magnitude of such losses is important for determining thermal noise levels in bonded suspensions for gravitational wave detectors. Three samples were investigated with bonds of varying geometries and surface areas. In two cases, the bonds were between two pieces of fused silica, whilst in the third a fused silica piece was attached to a sapphire substrate. In each case sodium silicate solution was used as the bonding agent. The thickness and Young's modulus of the bond material were evaluated enabling values for the intrinsic mechanical loss factor of the bonding material to be obtained
Mechanical dissipation in silicon flexures
No full textThe thermo-mechanical properties of silicon make it of significant interest as a possible material for mirror substrates and suspension elements for future long-baseline gravitational wave detectors. The mechanical dissipation in 92 μm thick 〈110〉 single-crystal silicon cantilevers has been observed over the temperature range 85 K to 300 K, with dissipation approaching levels down to ϕ=4.4×10−7
Integrative multi-omic cancer profiling reveals DNA methylation patterns associated with therapeutic vulnerability and cell-of-origin
No full textWe thank InPrint for the editing, Matthew A. Wyczalkowski for feedback on figures, and BioRender for diagrams. The Clinical Proteomic Tumor Analysis Consortium (CPTAC) is supported by the National Cancer Institute of the National Institutes of Health under award numbers U24CA210955, U24CA210985, U24CA210986, U24CA210954, U24CA210967, U24CA210972, U24CA210979, U24CA210993, U01CA214114, U01CA214116, and U01CA214125 as U24CA210972 to D.F. L.D. and S.P. and Contract GR0012005 to L.D. This project has been funded in part with Federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261201500003I, Task Order HHSN26100064. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products or organizations imply endorsement by the U.S. Government. Study Conception & Design: W.L. R.J.L. R.J. S.F. and L.D.; Performed Experiment or Data Collection: W.L. R.L. I.K. E.D. Y.L. S.S. and M.W.; Computational, Multi-omic, & Statistical Analyses: W.L, R.J.L. E.P. Y.S. A.G. and X.L.; Data Interpretation & Biological Analysis: W.L, R.J.L. R.G.J. S.M.F. E.P. Y.G. R.L. M.W. and H.S.; Writing - Original Drafts: W.L. and R.J.L.; Writing - Review & Editing: W.L. R.J.L. R.J. S.F. E.P. Y.G. M.C.W. Y.S. A.G. X.L. Y.L. D.R.M. K.R. A.L. A.R. and L.D.; Supervision: W.L. and L.D.; Administration:W.L. S.P. D.F. H.R. D.R.M. K.R. A.L. A.R. and L.D. The authors declare no competing interests. We support inclusive, diverse, and equitable conduct of research. During the preparation of this work the author(s) used ChatGPT to enhance its readability. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.We thank InPrint for the editing, Matthew A. Wyczalkowski for feedback on figures, and BioRender for diagrams. The Clinical Proteomic Tumor Analysis Consortium (CPTAC) is supported by the National Cancer Institute of the National Institutes of Health under award numbers U24CA210955, U24CA210985, U24CA210986, U24CA210954, U24CA210967, U24CA210972, U24CA210979, U24CA210993, U01CA214114, U01CA214116, and U01CA214125 as U24CA210972 to D.F., L.D., and S.P., and Contract GR0012005 to L.D. This project has been funded in part with Federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261201500003I, Task Order HHSN26100064. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products or organizations imply endorsement by the U.S. Government.DNA methylation plays a critical role in establishing and maintaining cellular identity. However, it is frequently dysregulated during tumor development and is closely intertwined with other genetic alterations. Here, we leveraged multi-omic profiling of 687 tumors and matched non-involved adjacent tissues from the kidney, brain, pancreas, lung, head and neck, and endometrium to identify aberrant methylation associated with RNA and protein abundance changes and build a Pan-Cancer catalog. We uncovered lineage-specific epigenetic drivers including hypomethylated FGFR2 in endometrial cancer. We showed that hypermethylated STAT5A is associated with pervasive regulon downregulation and immune cell depletion, suggesting that epigenetic regulation of STAT5A expression constitutes a molecular switch for immunosuppression in squamous tumors. We further demonstrated that methylation subtype-enrichment information can explain cell-of-origin, intra-tumor heterogeneity, and tumor phenotypes. Overall, we identified cis-acting DNA methylation events that drive transcriptional and translational changes, shedding light on the tumor's epigenetic landscape and the role of its cell-of-origin
Excess mechanical loss associated with dielectric mirror coatings on test masses in interferometric gravitational wave detectors
No full textInterferometric gravitational wave detectors use mirrors whose substrates are formed from materials of low intrinsic mechanical dissipation. The two most likely choices for the test masses in future advanced detectors are fused silica or sapphire (Rowan S et al 2000 Phys. Lett. A 265 5). These test masses must be coated to form mirrors, highly reflecting at 1064 nm. We have measured the excess mechanical losses associated with adding dielectric coatings to substrates of fused silica and calculated the effect of the excess loss on the thermal noise in an advanced interferometer
Experimental measurements of coating mechanical loss factors
No full textAll current gravitational wave detectors use test masses coated with alternating layers of two different dielectric materials to form highly reflective mirrors. The thermal noise from mechanical dissipation associated with such coatings may be significant for future detectors such as advanced LIGO. We have measured the mechanical dissipation of a number of types of coatings formed from SiO2 (silica) and Ta2O5 (tantala). The frequency dependence of the dissipation has been determined, taking into account the contribution of thermoelastic loss
Thermal noise in interferometric gravitational wave detectors due to dielectric optical coatings
No full textWe report on thermal noise from the internal friction of dielectric coatings made from alternating layers of Ta/sub 2/O/sub 5/ and SiO/sub 2/ deposited on fused silica substrates. We present calculations of the thermal noise in gravitational wave interferometers due to optical coatings, when the material proper-ties of the coating are different from those of the substrate and the mechanical loss angle in the coating is anisotropic. The loss angle in the coatings for strains parallel to the substrate surface was determined from ringdown experiments. We measured the mechanical quality factor of three fused silica samples with coatings deposited on them. The loss angle, phi /sub ||/(f), of the coating material for strains parallel to the coated surface was found to be 4.2 +or- 0.3 * 10/sup -4/ for coatings deposited on commercially polished slides, and 1.0 +or- 0.3 * 10/sup -4/ for a coating deposited on a superpolished disc. Using these numbers, we estimate the effect of coatings on thermal noise in the initial LIGO and Advanced LIGO interferometers. We also find that the corresponding prediction for thermal noise in the 40 m LIGO prototype at Caltech is consistent with the noise data. These results are complemented by results for a different type of coating, presented in a companion paper
Tunneling into microstate geometries: quantum effects stop gravitational collapse
No full text© 2016, The Author(s). Abstract: Collapsing shells form horizons, and when the curvature is small classical general relativity is believed to describe this process arbitrarily well. On the other hand, quantum information theory based (fuzzball/firewall) arguments suggest the existence of some structure at the black hole horizon. This structure can only form if classical general relativity stops being the correct description of the collapsing shell before it reaches the horizon size. We present strong evidence that classical general relativity can indeed break down prematurely, by explicitly computing the quantum tunneling amplitude of a collapsing shell of branes into smooth horizonless microstate geometries. We show that the amplitude for tunneling into microstate geometries with a large number of topologically non-trivial cycles is parametrically larger than e−SBH , which indicates that the shell can tunnel into a horizonless configuration long before the horizon has any chance to form. We also use this technology to investigate the tunneling of M2 branes into LLM bubbling geometries.sponsorship: We would like to thank Jan de Boer, Freddy Cachazo, Per Kraus, Alex Kusenko, Juan Maldacena, Stefano Massai, Thomas Van Riet and Nick Warner for enlightening discussions. The work of I.B. was supported in part by the ERC Starting Grant 240210 String-QCD-BH, by the John Templeton Foundation Grant 48222 and by a grant from the Foundational Questions Institute (FQXi) Fund, a donor advised fund of the Silicon Valley Community Foundation on the basis of proposal FQXi-RFP3-1321 (this grant was administered by Theiss Research). D.R.M is supported in part by NSF CAREER Grant PHY-0953232. This work is part of the research programme of the Foundation for Fundamental Research on Matter (FOM), which is part of the Netherlands Organisation for Scientific Research (NWO). The work of A.P. is supported by National Science Foundation Grant No. PHY12-05500. B.V. is supported by the European Commission through the Marie Curie Intra-European fellowship 328652-QM-sing. We are grateful to the Centro de Ciencias de Benasque Pedro Pascual for hospitality during this work. (ERC Starting Grant|240210 String-QCD-BH, John Templeton Foundation Grant|48222, Foundational Questions Institute (FQXi) Fund, Silicon Valley Community Foundation|FQXi-RFP3-1321, NSF CAREER Grant|PHY-0953232, National Science Foundation|PHY12-05500, European Commission|328652-QM-sing)status: Publishe
Damping and tuning of the fibre violin modes in monolithic silica suspensions
No full textHigh Q mirror suspensions are a key element of the advanced interferometric gravitational-wave detectors. In December 2002 the last of the final interferometer optics of GEO 600 were monolithically suspended, using fused silica fibres. The violin modes of the suspension fibres can have Q greater than 10(8) and can therefore interfere with the interferometer length control servo. Hence, the violin modes need to be damped, without degrading the pendulum Q itself. Furthermore, the frequency spread of the fibres used has to be small to allow for high Q notch filtering in the length control servo. ne requirements for the violin modes of the two GEO 600 inboard suspensions are Q lt 3 x 10(6) for the fundamental and Q lt 2 x 10(6) for the first harmonic mode, respectively. The frequency spread should not exceed 10% within one mode. To accomplish that, two sections of the fibres were coated with amorphous Teflon. By applying the coating, the Q of the relevant modes can be degraded to the desired values and furthermore, the frequencies of these modes can be tuned almost independently with a good accuracy over a wide range. After welding the fibres in the monolithic suspension, a corrective coating was applied to some fibres, to compensate for the frequency spread due to the tension spread of the four fibres within a suspension. We present the method and the results achieved
