12,122 research outputs found
On the first eigenvalue of the Dirichlet-to-Neumann operator on forms
We study a Dirichlet-to-Neumann eigenvalue problem for differential forms on
a compact Riemannian manifold with smooth boundary. This problem is a natural
generalization of the classical Steklov problem on functions. We derive a
number of upper and lower bounds for the first eigenvalue in several contexts:
many of these estimates will be sharp, and for some of them we characterize
equality. We also relate these new eigenvalues with those of other operators,
like the Hodge Laplacian or the biharmonic Steklov operator.Comment: 26 page
A compactness theorem for scalar-flat metrics on manifolds with boundary
Let (M,g) be a compact Riemannian manifold with boundary. This paper is
concerned with the set of scalar-flat metrics which are in the conformal class
of g and have the boundary as a constant mean curvature hypersurface. We prove
that this set is compact for dimensions greater than or equal to 7 under the
generic condition that the trace-free 2nd fundamental form of the boundary is
nonzero everywhere.Comment: 49 pages. Final version, to appear in Calc. Var. Partial Differential
Equation
An Optimizing Protocol Transformation for Constructor Finite Variant Theories in Maude-NPA
[EN] Maude-NPA is an analysis tool for cryptographic security
protocols that takes into account the algebraic properties of the cryptosystem. Maude-NPA can reason about a wide range of cryptographic
properties. However, some algebraic properties, and protocols using them,
have been beyond Maude-NPA capabilities, either because the cryptographic properties cannot be expressed using its equational unification
features or because the state space is unmanageable. In this paper, we
provide a protocol transformation that can safely get rid of cryptographic
properties under some conditions. The time and space difference between
verifying the protocol with all the crypto properties and verifying the
protocol with a minimal set of the crypto properties is remarkable. We
also provide, for the first time, an encoding of the theory of bilinear pairing into Maude-NPA that goes beyond the encoding of bilinear pairing
available in the Tamarin toolPartially supported by the EU (FEDER) and the Spanish MCIU under grant RTI2018-094403-B-C32, by the Spanish Generalitat Valenciana under grant PROMETEO/2019/098, and by the US Air Force Office of Scientific Research under award number FA9550-17-1-0286. Julia Sapiña has been supported by the Generalitat Valenciana APOSTD/2019/127 grantAparicio-Sánchez, D.; Escobar Román, S.; Gutiérrez Gil, R.; Sapiña-Sanchis, J. (2020). An Optimizing Protocol Transformation for Constructor Finite Variant Theories in Maude-NPA. Springer Nature. 230-250. https://doi.org/10.1007/978-3-030-59013-0_12S230250Maude-NPA manual v3.1. http://maude.cs.illinois.edu/w/index.php/Maude_Tools:_Maude-NPAThe Tamarin-Prover Manual, 4 June 2019. https://tamarin-prover.github.io/manual/tex/tamarin-manual.pdfAl-Riyami, S.S., Paterson, K.G.: Tripartite authenticated key agreement protocols from pairings. In: Paterson, K.G. (ed.) Cryptography and Coding 2003. LNCS, vol. 2898, pp. 332–359. Springer, Heidelberg (2003). https://doi.org/10.1007/978-3-540-40974-8_27Baader, F., Snyder, W.: Unification theory. In: Robinson, J.A., Voronkov, A. (eds.) Handbook of Automated Reasoning, vol. 1, pp. 447–533. Elsevier Science (2001)Baelde, D., Delaune, S., Gazeau, I., Kremer, S.: Symbolic verification of privacy-type properties for security protocols with XOR. In: 30th IEEE Computer Security Foundations Symposium, CSF 2017, pp. 234–248. IEEE Computer Society (2017)Blanchet, B.: Modeling and verifying security protocols with the applied pi calculus and ProVerif. Found. Trends Privacy Secur. 1(1–2), 1–135 (2016)Clavel, M., et al.: Maude manual (version 3.0). Technical report, SRI International, Computer Science Laboratory (2020). http://maude.cs.uiuc.eduComon-Lundh, H., Delaune, S.: The finite variant property: how to get rid of some algebraic properties. In: Giesl, J. (ed.) RTA 2005. LNCS, vol. 3467, pp. 294–307. Springer, Heidelberg (2005). https://doi.org/10.1007/978-3-540-32033-3_22Cremers, C.J.F.: The scyther tool: verification, falsification, and analysis of security protocols. In: Gupta, A., Malik, S. (eds.) CAV 2008. LNCS, vol. 5123, pp. 414–418. Springer, Heidelberg (2008). https://doi.org/10.1007/978-3-540-70545-1_38Dreier, J., Duménil, C., Kremer, S., Sasse, R.: Beyond subterm-convergent equational theories in automated verification of stateful protocols. In: Maffei, M., Ryan, M. (eds.) POST 2017. LNCS, vol. 10204, pp. 117–140. Springer, Heidelberg (2017). https://doi.org/10.1007/978-3-662-54455-6_6Escobar, S., Hendrix, J., Meadows, C., Meseguer, J.: Diffie-Hellman cryptographic reasoning in the Maude-NRL protocol analyzer. In: Proceedings of 2nd International Workshop on Security and Rewriting Techniques (SecReT 2007) (2007)Escobar, S., Meadows, C., Meseguer, J.: A rewriting-based inference system for the NRL protocol analyzer and its meta-logical properties. Theor. Comput. Sci. 367(1–2), 162–202 (2006)Escobar, S., Meadows, C., Meseguer, J.: Maude-NPA: cryptographic protocol analysis modulo equational properties. In: Aldini, A., Barthe, G., Gorrieri, R. (eds.) FOSAD 2007-2009. LNCS, vol. 5705, pp. 1–50. Springer, Heidelberg (2009). https://doi.org/10.1007/978-3-642-03829-7_1Escobar, S., et al.: Protocol analysis in Maude-NPA using unification modulo homomorphic encryption. In: Proceedings of PPDP 2011, pp. 65–76. ACM (2011)Escobar, S., Meadows, C.A., Meseguer, J., Santiago, S.: State space reduction in the Maude-NRL protocol analyzer. Inf. Comput. 238, 157–186 (2014)Escobar, S., Sasse, R., Meseguer, J.: Folding variant narrowing and optimal variant termination. J. Log. Algebr. Program. 81(7–8), 898–928 (2012)Fabrega, F.J.T., Herzog, J.C., Guttman, J.D.: Strand spaces: why is a security protocol correct? In: Proceedings of IEEE Symposium on Security and Privacy, pp. 160–171 (1998)Guttman, J.D.: Security goals and protocol transformations. In: Mödersheim, S., Palamidessi, C. (eds.) TOSCA 2011. LNCS, vol. 6993, pp. 130–147. Springer, Heidelberg (2012). https://doi.org/10.1007/978-3-642-27375-9_8Joux, A.: A one round protocol for tripartite Diffie-Hellman. In: Bosma, W. (ed.) ANTS 2000. LNCS, vol. 1838, pp. 385–393. Springer, Heidelberg (2000). https://doi.org/10.1007/10722028_23Kim, Y., Perrig, A., Tsudik, G.: Communication-efficient group key agreement. In: Dupuy, M., Paradinas, P. (eds.) SEC 2001. IIFIP, vol. 65, pp. 229–244. Springer, Boston, MA (2002). https://doi.org/10.1007/0-306-46998-7_16Küsters, R., Truderung, T.: Using ProVerif to analyze protocols with Diffie-Hellman exponentiation. In: IEEE Computer Security Foundations, pp. 157–171 (2009)Küsters, R., Truderung, T.: Reducing protocol analysis with XOR to the XOR-free case in the horn theory based approach. J. Autom. Reason. 46(3–4), 325–352 (2011)Meadows, C.: The NRL protocol analyzer: an overview. J. Logic Program. 26(2), 113–131 (1996)Meier, S., Cremers, C., Basin, D.: Strong invariants for the efficient construction of machine-checked protocol security proofs. In: 2010 23rd IEEE Computer Security Foundations Symposium, pp. 231–245 (2010)Meseguer, J.: Conditional rewriting logic as a united model of concurrency. Theoret. Comput. Sci. 96(1), 73–155 (1992)Meseguer, J.: Variant-based satisfiability in initial algebras. Sci. Comput. Program. 154, 3–41 (2018)Meseguer, J.: Generalized rewrite theories, coherence completion, and symbolic methods. J. Log. Algebr. Meth. Program. 110, 100483 (2020)Mödersheim, S., Viganò, L.: The open-source fixed-point model checker for symbolic analysis of security protocols. In: Aldini, A., Barthe, G., Gorrieri, R. (eds.) FOSAD 2007-2009. LNCS, vol. 5705, pp. 166–194. Springer, Heidelberg (2009). https://doi.org/10.1007/978-3-642-03829-7_6Sasse, R., Escobar, S., Meadows, C., Meseguer, J.: Protocol analysis modulo combination of theories: a case study in Maude-NPA. In: Cuellar, J., Lopez, J., Barthe, G., Pretschner, A. (eds.) STM 2010. LNCS, vol. 6710, pp. 163–178. Springer, Heidelberg (2011). https://doi.org/10.1007/978-3-642-22444-7_11Schmidt, B., Sasse, R., Cremers, C., Basin, D.A.: Automated verification of group key agreement protocols. In: 2014 IEEE Symposium on Security and Privacy, SP 2014, pp. 179–194. IEEE Computer Society (2014)Skeirik, S., Meseguer, J.: Metalevel algorithms for variant satisfiability. J. Log. Algebraic Methods Program. 96, 81–110 (2018)TeReSe: Term Rewriting Systems. Cambridge University Press, Cambridge (2003)Yang, F., Escobar, S., Meadows, C.A., Meseguer, J., Narendran, P.: Theories of homomorphic encryption, unification, and the finite variant property. In: Proceedings of PPDP 2014, pp. 123–133. ACM (2014
Increase of cold tolerance in cotton plant (Gossypium hirsutum L.) by mepiquat chloride
Three mepiquat chloride (MC) concentrations - 40, 70, and 100 g a.i./ha - were used to spray cotton (Gossypium hirsutum L., cultival McNair 220) plants to determine whether or not MC would increase their cold tolerance. Seven to ten days after the spray, the plants were exposed to three different cold treatments. No important difference in cold damage was noticed between the control and the MC-treated plants when they were exposed repeatedly to 4.5 C. No plants died when exposed to 0.5 C for 12 h; however, 90% of the 1st and 2nd leaves of the control plants were damaged. This was three times more damage than those leaves of plants treated with 70 and 100 g a.i./ha MC concentrations; 60% f the control and 10-20% of the MC-treated plants died when the plants were subjected to a cold hardening process with 15.5 C day (12 h) and 1.7 C night (12 h) for 10 days, and then, held at -2.2 C for 24 hours. The electrolyte leakage and reflectance measurement data showed that the cell membranes of the MC-treated plants sustained much less damage than those of the control. Freezing injury was easily assessed by reflectance measurements at the 1.65 micrometer wavelength
Inelastic and elastic collision rates for triplet states of ultracold strontium
We report measurement of the inelastic and elastic collision rates for
^{88}Sr atoms in the (5s5p)^3P_0 state in a crossed-beam optical dipole trap.
This is the first measurement of ultracold collision properties of a ^3P_0
level in an alkaline-earth atom or atom with similar electronic structure.
Since the (5s5p)^3P_0 state is the lowest level of the triplet manifold, large
loss rates indicate the importance of principle-quantum-number-changing
collisions at short range. We also provide an estimate of the collisional loss
rates for the (5s5p){^3P_2} state.Comment: 4 pages 5 figure
Doping of inorganic materials in microreactors – preparation of Zn doped Fe₃O₄ nanoparticles
Microreactor systems are now used more and more for the continuous production of metal nanoparticles and metal oxide nanoparticles owing to the controllability of the particle size, an important property in many applications. Here, for the first time, we used microreactors to prepare metal oxide nanoparticles with controlled and varying metal stoichiometry. We prepared and characterised Zn-substituted Fe₃O₄ nanoparticles with linear increase of Zn content (ZnxFe₃−xO₄ with 0 ≤ x ≤ 0.48), which causes linear increases in properties such as the saturation magnetization, relative to pure Fe₃O₄. The methodology is simple and low cost and has great potential to be adapted to the targeted doping of a vast array of other inorganic materials, allowing greater control on the chemical stoichiometry for nanoparticles prepared in microreactors
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