Adaptive waveform inversion: theory

Conventional full-waveform seismic inversion attempts to find a model of the subsurface that is able to predict observed seismic waveforms exactly; it proceeds by minimizing the difference between the observed and predicted data directly, iterating in a series of linearized steps from an assumed starting model. If this starting model is too far removed from the true model, then this approach leads to a spurious model in which the predicted data are cycle skipped with respect to the observed data. Adaptive waveform inversion (AWI) provides a new form of full-waveform inversion (FWI) that appears to be immune to the problems otherwise generated by cycle skipping. In this method, least-squares convolutional filters are designed that transform the predicted data into the observed data. The inversion problem is formulated such that the subsurface model is iteratively updated to force these Wiener filters toward zero-lag delta functions. As that is achieved, the predicted data evolve toward the observed data and the assumed model evolves toward the true model. This new method is able to invert synthetic data successfully, beginning from starting models and under conditions for which conventional FWI fails entirely. AWI has a similar computational cost to conventional FWI per iteration, and it appears to converge at a similar rate. The principal advantages of this new method are that it allows waveform inversion to begin from less-accurate starting models, does not require the presence of low frequencies in the field data, and appears to provide a better balance between the influence of refracted and reflected arrivals upon the final-velocity model. The AWI is also able to invert successfully when the assumed source wavelet is severely in error

Quantum SUSY signatures in low and high energy processes

In the search for phenomenological evidence of supersymmetry through the indirect method of quantum signatures, it is useful to seek correlations of the non-standard quantum effects in low and high energy proceses, such as those involving on one hand the properties of the B-mesons and on the other hand the physics of the top quark and of the Higgs bosons. There are regions of the MSSM parameter space where the potential quantum SUSY signatures in the two energy regimes are strongly interwoven and therefore the eventual detection of these correlated quantum effects would strongly point towards the existence of underlying supersymmetric dynamics.Comment: 17 pages, LaTeX, 7 figs included with epsfig. Talk at the 5th International Workshop on High Energy Physics Phenomenology (WHEPP-5). To appear in the Proceeding

Agriculture and the transition to the market

Agricultural sectors in Eastern and Central Europe are large so that changes in producer prices, farm employment, and land ownership affect substantial numbers of people. In the past, food in the region was politicized. For decades, governments of Eastern European countries and the USSR offered their citizens stable, subsidized food prices and a steadily improving diet in an effort to demonstrate the superiority of communism over capitalism. During the transition, the context has changed, but food remains politicized. Many consumers in the region are ill-prepared to pay the real costs of food, which are quite high. The task of reducing those costs will be difficult, involving restructuring of farms and fostering competition in processing and distribution. Management of the agricultural transition will affect the political sustainability of the process and influence agriculture's contribution to the growth of emerging market economies. Although the agricultural sector of Eastern and Central Europe is large, Soviet agriculture dwarfs it in its impact on the region and the world. A positive program to stop the decline in Soviet agriculture could contribute to economic growth and political stability. Failure to remedy the fundamental flaws in Soviet agriculture will speed the country's slide into poverty and ethnic turmoil - and undermine the efforts of Central and Eastern Europeans to succeed.Access to Markets,Environmental Economics&Policies,Economic Theory&Research,Agricultural Knowledge&Information Systems,Markets and Market Access

Preface: Introduction to special issue

Peer ReviewedPostprint (author’s final draft

Production and FCNC decay of supersymmetric Higgs bosons into heavy quarks in the LHC

We analyze the production and subsequent decay of the neutral MSSM Higgs bosons (h = h^0, H^0, A^0) mediated by flavor changing neutral currents (FCNC) in the LHC collider. We have computed the h-production cross-section times the FCNC branching ratio, \sigma(pp -> h -> qq') = \sigma(pp -> h) B(h -> qq'), in the LHC focusing on the strongly-interacting FCNC sector. Here qq' is an electrically neutral pair of quarks of different flavors, the dominant modes being those containing a heavy quark: tc or bs. We determine the maximum production rates for each of these modes and identify the relevant regions of the MSSM parameter space, after taking into account the severe restrictions imposed by low energy FCNC processes. The analysis of \sigma(pp -> h -> qq') singles out regions of the MSSM parameter space different from those obtained by maximizing only the branching ratio, due to non-trivial correlations between the parameters that maximize/minimize each isolated factor. The production rates for the bs channel can be huge for a FCNC process (0.1-1 pb), but its detection can be problematic. The production rates for the tc channel are more modest (10^{-3}-10^{-2} pb), but its detection should be easier due to the clear-cut top quark signature. A few thousand tc events could be collected in the highest luminosity phase of the LHC, with no counterpart in the SM.Comment: 25 pages, 9 figures, 2 tables, LaTeX 2e. Typos corrected. Version to appear in JHE

Supersymmetry Tests from a Combined Analysis of Chargino and Charged Higgs Boson Pair Production at a 1 TeV Linear Collider

We consider the production of chargino and charged Higgs boson pairs at future linear colliders for c.m. energies in the one TeV range. Working in the MSSM under the assumption of a "moderately" light SUSY scenario, we compute the leading (double) and next-to leading (linear) supersymmetric logarithmic terms of the so-called "Sudakov expansion" at one loop. We show that a combined analysis of the slopes of the chargino and of the charged Higgs production cross sections would offer a simple possibility for determining $\tan\beta$ for large ($\gtrsim 10$) values and an allowed strip in the ($M_2,\mu$) plane. This could provide a strong consistency test of the considered supersymmetric model.Comment: 4 pages, 4 Encapsulated PostScript Figure

Noise radiated from a periodically stiffened cylindrical shell excited by a turbulent boundary layer

© 2019 Elsevier Ltd This work proposes a semi-analytical method to model the vibroacoustic behavior of submerged cylindrical shells periodically stiffened by axisymmetric frames and excited by a homogeneous and fully developed turbulent boundary layer (TBL). The process requires the computation of the TBL wall-pressure cross spectral density function and the sensitivity functions for stiffened cylindrical shells. The former is deduced from an existent TBL model and the latter are derived from a wavenumber-point reciprocity principle and a spectral formulation of the problem. The stiffeners' dynamic behavior is introduced in the formulation through circumferential admittances that are computed by a standard finite element code using shell elements. Four degrees of freedom are taken into account for the coupling between the shell and the stiffeners: three translation directions and one tangential rotation. To investigate the effect of the stiffeners on the radiated noise, two case studies are considered. The first one examines a fluid-loaded cylindrical shell with regularly spaced simple supports. The influence of Bloch-Floquet waves and the support spacing on the noise radiation are highlighted. The second case study inspects the fluid-loaded cylindrical shell with two different periodic ring stiffeners, namely stiffeners with T-shaped and I-shaped cross-sections. Their influence on the vibroacoustics of the shell is thoroughly analyzed

Nuevas perspectivas en la evaluación de las patentes como parte del curriculum científico

During the last years the consideration of the patents as part of the scientific curriculum has been changing from the activity of technologists and researchers devoted to applied science to a fundamental part of the scientific curriculum of well-known researchers. Some time ago, patents were simply not considered in teaching evaluation at University or its equivalent at CSIC (Spanish National Research Council) and only considered as a second range parameter in the scientific evaluation. In promotion competition they have change from a marginal factor when the number of papers and their impact factor were comparable, to become a decisive factor or even a «sine qua non» condition in specific areas. As it happens to a great extent in publications, the number of patent applications is not an indicator of the quality or importance of the knowledge they present; however their monopoly of exploitation and its costs makes patents totally different and introduces variables difficult to quantify in scientific evaluation. Changes in CSIC legal structure and management definition as a Key Institution in the Spanish Innovation System and the fact of its being the most active patent applicant (5th public institution as EPO applicant), besides the changes in its Technology Transfer management, should affect the decision to patent. Its value in research activity acknowledgement requires more precise indicators to reflect «ex ante» its impact on the scientific community as well as on society welfare, because at the end of patent life its real market incidence shows the impact of the research results presented in a patent.En los últimos años la consideración de las patentes como currículo del investigador ha ido cambiando progresivamente, de ser la actividad propia de tecnólogos e investigadores centrados en investigación aplicada, a ser también parte fundamental del currículo de investigadores de prestigio en ciencia básica. Antes, simplemente no eran tenidas en cuenta en la evaluación docente en la Universidad o su equivalente en el CSIC y apenas eran consideradas como actividad accesoria o secundaria dentro de la evaluación de la actividad investigadora. El cambio ha sido más ostensible en promoción por concurso, de ser un mero elemento de desempate cuando el número de publicaciones y su factor de impacto era comparable, ha pasado a ser determinante o una condición «sine qua non» en determinadas áreas científicas. Al igual que ocurre en el resto de publicaciones, el número de patentes no indica la calidad y el significado del conocimiento en ellas recogido, pero el monopolio de explotación comercial y el coste que conllevan sí es marcadamente diferente e introduce variables de difícil consideración en las evaluaciones. Los cambios en la estructura jurídica y en el funcionamiento de instituciones claves en el Sistema Español de Innovación como el CSIC, su mayor institución patentadora (entidad española con mayor número de patentes nacionales y quinto organismo público de investigación por número de patentes europeas), así como la figura jurídica elegida para gestionar la Transferencia de Tecnología en el CSIC, van a suponer nuevos condicionantes a la decisión de patentar. Su valor en el reconocimiento de la actividad investigadora exige indicadores cada vez más precisos, y que indiquen a priori su repercusión en la comunidad científica y especialmente en el resto de la sociedad, ya que, a diferencia con el resto de publicaciones al final de su vida, su repercusión de mercado marca el impacto que la patente tiene como resultado de investigación

Flavour changing effects on e^+ e^- -> H b \bar{s}, H \bar{b} s in the MSSM

Flavour changing effects originating from the exchange of scalar particles in the processes e^+ e^- -> H b \bar{s}, H \bar{b} s, with H = h^0, H^0, A^0, are investigated in the Minimal Supersymmetric Standard Model with non-minimal flavour violation at the one-loop level. The dominating SUSY-QCD contributions with squark--gluino loops are calculated and discussed. We consider the SUSY scenario with non-minimal flavour mixing in the down-type squark-mass matrix. The flavour-changing cross sections are derived, and we discuss the dependence on the MSSM parameters and the strength of flavour mixing. The values for the cross section can reach 10^{-4} pb for the production of the heavy Higgs boson H^0 or A^0, and only 10^{-7} pb for the light Higgs boson h^0. Non-decoupling behaviour occurs for both h^0, H^0 production in the case of a common heavy SUSY mass scale.Comment: LaTeX, 20 pages, 11 figures. Discussion and references added. Published version in Eur.Phys.J.