Mathematical model and numerical simulation of slow deformation waves in the earth’s crust structural elements

Numerical calculations of the formation and propagation of slow deformation waves in geological media are performed. The velocities of such a tectonic movements usually lie within the range of 1–100 km/year and these movements are treated as slow deformation waves. The deformation autowaves are shown to make a considerable contribution into the formation of fracture foci. When two such autowaves collide, they behave similar to solitons, reflecting from each other as elastic particles. The deformation autowaves form at the boundaries of structural elements, e.g., blocks of a geomedium during their fast movements. An autowave in a geomedium is developed due to a local loss of stability, and the velocity of its motion is found to be proportional to the velocity of crush movement (motion velocity of the grip during the formation of a Lüders front)

Using rhythmic nonces for puzzle-based DoS resistance

To protect against replay attacks, many Internet proto-cols rely on nonces to guarantee freshness. In practice, the server generates these nonces during the initial hand-shake, but if the server is under attack, resources con-sumed by managing certain protocols can lead to DoS vulnerabilities. To help alleviate this problem, we pro-pose the concept of rhythmic nonces, a cryptographic tool that allows servers to measure request freshness with minimal bookkeeping costs. We explore the impact of this service in the context of a puzzle-based DoS re-sistance scheme we call “SYN puzzles”. Our preliminary results based on mathematical analysis and evaluation of a prototype suggests that our scheme is more resistant than existing techniques. 1

Медленные деформационные фронты. Модель и особенности распространения

Our study aimed at investigating the origin and development of ‘slow’ movements in a solid body/medium under loading and studying the role of such movements in the occurrence of critical states, i.e. sources of destruction in a stable solid medium. Computerized modeling was conducted to simulate the evolution of the stress-strain state and the formation of slow deformation waves in a loaded medium. We have developed and justified a mathematical model of the loaded elastoplastic medium, which demonstrates the joint generation and propagation of ordinary stress waves (propagating with the velocity of sound) and slow deformation waves of the inelastic nature. The propagation rates of the latter are 5–7 orders of magnitude lower than the velocity of sound. The features of slow deformation wave propagation in the solid media are investigated. In the model, slow deformation waves interact under certain conditions as solitons and penetrate each other. Considering the properties, they are similar to both solitons satisfying the solutions of the non-linear Korteweg – de Vries equation and kinks satisfying the solutions of the sin-Gordon equation. Slow deformation fronts are actively involved into the formation of sources of destruction and provide an effective mechanism for the transfer and redistribution of energy in the loaded medium.Цель работы заключалась в разработке модельных представлений о природе «медленных» движений в нагружаемых твердых телах и средах и в изучении их роли в формировании критических состояний – очагов разрушения в прочной среде. Методика исследований – численное моделирование эволюции напряженно-деформированного состояния и формирования в нагружаемой среде медленных волн деформации. Разработан и обоснован вариант математической модели описания процессов совместной генерации и распространения в нагружаемых упругопластических средах как обычных волн напряжений, распространяющихся со скоростями звука, так и медленных деформационных волн неупругой природы, скорости которых на 5–7 порядков ниже скоростей звука. Исследованы особенности распространения медленных деформационных волн в прочных средах. Показано, что медленные деформационные волны при определенных условиях взаимодействуют как солитоны, проникая друг через друга. Их свойства сходны со свойствами как солитонов, получаемых решениями нелинейного уравнения Кортевега – де-Фриза, так и кинков – решений уравнения sin-Гордона. Показано, что медленные деформационные фронты активно участвуют в формировании очага разрушения, являясь эффективным механизмом переноса и перераспределения энергии в нагружаемой среде

Measurement of the WW Boson Mass

A measurement of the mass of the $W$ boson is presented based on a sample of 5982 $W \rightarrow e \nu$ decays observed in $p\overline{p}$ collisions at $\sqrt{s}$ = 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a fit to the transverse mass spectrum, combined with measurements of the $Z$ boson mass, the $W$ boson mass is measured to be $M_W = 80.350 \pm 0.140 (stat.) \pm 0.165 (syst.) \pm 0.160 (scale) GeV/c^2$.Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures (submitted to PRL

Search for W~1Z~2\widetilde{W}_1\widetilde{Z}_2 Production via Trilepton Final States in ppˉp\bar{p} collisions at s=1.8\sqrt{s}=1.8 TeV

We have searched for associated production of the lightest chargino, $\widetilde{W}_1$, and next-to-lightest neutralino, $\widetilde{Z}_2$, of the Minimal Supersymmetric Standard Model in $p\bar{p}$ collisions at \mbox{$\sqrt{s}$ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron collider. Data corresponding to an integrated luminosity of 12.5$\pm 0.7$ \ipb were examined for events containing three isolated leptons. No evidence for $\widetilde{W}_1\widetilde{Z}_2$ pair production was found. Limits on $\sigma(\widetilde{W}_1\widetilde{Z}_2)$Br$(\widetilde{W}_1\to l\nu\widetilde{Z}_1)$Br$(\widetilde{Z}_2\to l\bar{l}\widetilde{Z}_1)$ are presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted to Physical Review Letters. Replace comments - Had to resumbmit version with EPSF directive

Second Generation Leptoquark Search in p\bar{p} Collisions at s\sqrt{s} = 1.8 TeV

We report on a search for second generation leptoquarks with the D\O\ detector at the Fermilab Tevatron $p\bar{p}$ collider at $\sqrt{s}$ = 1.8 TeV. This search is based on 12.7 pb$^{-1}$ of data. Second generation leptoquarks are assumed to be produced in pairs and to decay into a muon and quark with branching ratio $\beta$ or to neutrino and quark with branching ratio $(1-\beta)$. We obtain cross section times branching ratio limits as a function of leptoquark mass and set a lower limit on the leptoquark mass of 111 GeV/c$^{2}$ for $\beta = 1$ and 89 GeV/c$^{2}$ for $\beta = 0.5$ at the 95%\ confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-

The Azimuthal Decorrelation of Jets Widely Separated in Rapidity

This study reports the first measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units. The data were accumulated using the D{\O}detector during the 1992--1993 collider run of the Fermilab Tevatron at $\sqrt{s}=$ 1.8 TeV. These results are compared to next--to--leading order (NLO) QCD predictions and to two leading--log approximations (LLA) where the leading--log terms are resummed to all orders in $\alpha_{\scriptscriptstyle S}$. The final state jets as predicted by NLO QCD show less azimuthal decorrelation than the data. The parton showering LLA Monte Carlo {\small HERWIG} describes the data well; an analytical LLA prediction based on BFKL resummation shows more decorrelation than the data.Comment: 6 pages with 4 figures, all uuencoded and gzippe

Jet Production via Strongly-Interacting Color-Singlet Exchange in ppˉp\bar{p} Collisions

A study of the particle multiplicity between jets with large rapidity separation has been performed using the D{\O}detector at the Fermilab Tevatron $p\bar{p}$ Collider operating at $\sqrt{s}=1.8$ TeV. A significant excess of low-multiplicity events is observed above the expectation for color-exchange processes. The measured fractional excess is $1.07 \pm 0.10({\rm stat})^{+ 0.25}_{- 0.13}({\rm syst})$, which is consistent with a strongly-interacting color-singlet (colorless) exchange process and cannot be explained by electroweak exchange alone. A lower limit of 0.80% (95% C.L.) is obtained on the fraction of dijet events with color-singlet exchange, independent of the rapidity gap survival probability.Comment: 15 pages (REVTeX), 3 PS figs (uuencoded/tar compressed, epsf.sty) Complete postscript available at http://d0sgi0.fnal.gov/d0pubs/journals.html Submitted to Physical Review Letter

Measurement of the ZZγZZ\gamma and ZγγZ\gamma\gamma Couplings in ppˉp\bar p Collisions at s=1.8\sqrt{s} = 1.8 TeV

We have directly measured the ZZ-gamma and Z-gamma-gamma couplings by studying p pbar --> l+ l- gamma + X, (l = e, mu) events at the CM energy of 1.8$TeV with the D0 detector at the Fermilab Tevatron Collider. A fit to the transverse energy spectrum of the photon in the signal events, based on the data set corresponding to an integrated luminosity of 13.9 pb^-1 ($13.3 pb^-1) for the electron (muon) channel, yields the following 95% confidence level limits on the anomalous CP-conserving ZZ-gamma couplings: -1.9 < h^Z_30 < 1.8 (h^Z_40 = 0), and -0.5 < h^Z_40 < 0.5 (h^Z_30 = 0), for a form-factor scale Lambda = 500 GeV. Limits for the Z-gamma-gamma$ couplings and CP-violating couplings are also discussed.Comment: 11 pages, 1 table, and 3 figure