Now showing items 46-65 of 79

    • The observational limit of wave packets with noisy measurements 

      Caro, P.; Meroño, C. (2019)
      The authors consider the problem of recovering an observable from certain measurements containing random errors. The observable is given by a pseudodifferential operator while the random errors are generated by a Gaussian ...
    • On Bloom type estimates for iterated commutators of fractional integrals 

      Accomazzo, N.; Martinez-Perales, J.C.; Rivera-Ríos, I.P. (2018-04)
      In this paper we provide quantitative Bloom type estimates for iterated commutators of fractional integrals improving and extending results from [15]. We give new proofs for those inequalities relying upon a new sparse ...
    • On extension problem, trace hardy and Hardy’s inequalities for some fractional Laplacians 

      Boggarapu, P.; Roncal, L.Autoridad BCAM; Thangavelu, S. (2019-09)
      We obtain generalised trace Hardy inequalities for fractional powers of general operators given by sums of squares of vector fields. Such inequalities are derived by means of particular solutions of an extended equation ...
    • On pointwise and weighted estimates for commutators of Calderón-Zygmund operators 

      Lerner, A. K; Ombrosi, S.; Rivera-Ríos, I.P. (2017)
      In recent years, it has been well understood that a Calderón-Zygmund operator T is pointwise controlled by a finite number of dyadic operators of a very simple structure (called the sparse operators). We obtain a similar ...
    • On sums involving Fourier coefficients of Maass forms for SL(3,Z) 

      Jääsaari, J.; Vesalainen, E.V. (2016-09-10)
      We derive a truncated Voronoi identity for rationally additively twisted sums of Fourier coefficients of Maass forms for SL(3,Z), and as an application obtain a pointwise estimate and a second moment estimate for the sums ...
    • On the absolute divergence of Fourier series in the infinite dimensional torus 

      Fernández, E.; Roncal, L.Autoridad BCAM (2019-03-22)
      In this note we present some simple counterexamples, based on quadratic forms in infinitely many variables, showing that the implication $f\in C^{(\infty}(\mathbb{T}^\omega)\Longrightarrow\sum_{\bar{p}\in\mathbb{Z}^\inf ...
    • Pointwise Convergence over Fractals for Dispersive Equations with Homogeneous Symbol 

      Eceizabarrena, D.; Ponce Vanegas, F.Autoridad BCAM (2021-08-24)
      We study the problem of pointwise convergence for equations of the type $i\hbar\partial_tu + P(D)u = 0$, where the symbol $P$ is real, homogeneous and non-singular. We prove that for initial data $f\in H^s(\mathbb{R}^n)$ ...
    • Proof of an extension of E. Sawyer's conjecture about weighted mixed weak-type estimates 

      Li, K.; Ombrosi, S.; Pérez, C.Autoridad BCAM (2018-09)
      We show that if $v\in A_\infty$ and $u\in A_1$, then there is a constant $c$ depending on the $A_1$ constant of $u$ and the $A_{\infty}$ constant of $v$ such that $$\Big\|\frac{ T(fv)} {v}\Big\|_{L^{1,\infty}(uv)}\le c\, ...
    • A quantitative approach to weighted Carleson condition 

      Rivera-Ríos, I.P. (2017-05-05)
      Quantitative versions of weighted estimates obtained by F. Ruiz and J.L. Torrea for the operator \[ \mathcal{M}f(x,t)=\sup_{x\in Q,\,l(Q)\geq t}\frac{1}{|Q|}\int_{Q}|f(x)|dx \qquad x\in\mathbb{R}^{n}, \, t \geq0 \] are ...
    • Quantitative weighted estimates for rough homogeneous singular integrals 

      Hytönen, T.P.; Roncal, L.Autoridad BCAM; Tapiola, O. (2017-03-11)
      We consider homogeneous singular kernels, whose angular part is bounded, but need not have any continuity. For the norm of the corresponding singular integral operators on the weighted space $L^2(w)$, we obtain a bound ...
    • Quantitative weighted estimates for Rubio de Francia's Littlewood--Paley square function 

      Garg, R.; Roncal, L.Autoridad BCAM; Shrivastava, S. (2019-12)
      We consider the Rubio de Francia's Littlewood--Paley square function associated with an arbitrary family of intervals in $\mathbb{R}$ with finite overlapping. Quantitative weighted estimates are obtained for this operator. ...
    • Quantitative weighted estimates for singular integrals and commutators 

      Rivera-Ríos, I.P. (2018-02-27)
      In this dissertation several quantitative weighted estimates for singular integral op- erators, commutators and some vector valued extensions are obtained. In particular strong and weak type $(p, p)$ estimates, Coifman-Fe ...
    • Quantitative weighted mixed weak-type inequalities for classical operators 

      Ombrosi, S.; Pérez, C.Autoridad BCAM; Recchi, J. (2016-06-30)
      We improve on several mixed weak type inequalities both for the Hardy-Littlewood maximal function and for Calderón-Zygmund operators. These type of inequalities were considered by Muckenhoupt and Wheeden and later on by ...
    • Reconstruction of the Derivative of the Conductivity at the Boundary 

      Ponce Vanegas, F.Autoridad BCAM (2019-08)
      We describe a method to reconstruct the conductivity and its normal derivative at the boundary from the knowledge of the potential and current measured at the boundary. This boundary determination implies the uniqueness ...
    • Regularity of maximal functions on Hardy–Sobolev spaces 

      Pérez, C.Autoridad BCAM; Picón, T.; Saari, Olli; Sousa, Mateus (2018-12-01)
      We prove that maximal operators of convolution type associated to smooth kernels are bounded in the homogeneous Hardy–Sobolev spaces H1,p(Rd) when p > d/(d + 1). This range of exponents is sharp. As a by-product of the ...
    • RESTRICTED TESTING FOR POSITIVE OPERATORS 

      Hytönen, T.; Li, K.; Sawyer, E. (2020)
      We prove that for certain positive operators T, such as the Hardy-Littlewood maximal function and fractional integrals, there is a constant D>1, depending only on the dimension n, such that the two weight norm inequality ...
    • Reverse Hölder Property for Strong Weights and General Measures 

      Luque, T.; Pérez, C.Autoridad BCAM; Rela, E. (2016-06-30)
      We present dimension-free reverse Hölder inequalities for strong $A^{\ast}_p$ weights, $1 \le p < \infty$. We also provide a proof for the full range of local integrability of $A^{\ast}_1$ weights. The common ingredient ...
    • Rotational smoothing 

      Caro, P.; Meroño, C.; Parissis, I. (2022-01-05)
      Rotational smoothing is a phenomenon consisting in a gain of regularity by means of averaging over rotations. This phenomenon is present in operators that regularize only in certain directions, in contrast to operators ...
    • Scattering with critically-singular and δ-shell potentials 

      Caro, P.; García, A. (2019)
      The authors consider a scattering problem for electric potentials that have a component which is critically singular in the sense of Lebesgue spaces, and a component given by a measure supported on a compact Lipschitz ...
    • Sharp reverse Hölder inequality for Cp weights and applications 

      Canto, J. (2020)
      We prove an appropriate sharp quantitative reverse Hölder inequality for the $C_p$ class of weights fromwhich we obtain as a limiting case the sharp reverse Hölder inequality for the $A_\infty$ class of weights (Hytönen ...