Evolution of the Kurile-Kamchatkan Volcanic Arcs and Dynamics of the Kamchatka-Aleutian junction

The Cenozoic tectonic evolution of the Kurile-Kamchatkan arc system has been reconstructed based on the spatial-tectonic setting of the volcanic-rock formations and their petrologic-geochemical characteristics, using gravity and seismic data. Three volcanic arc trench systems of different ages that become successively younger toward the Pacific have been recognized in the region: the West Kamchatka (Eocene), Mid-Kamchatka-Kurile (Late Oligocene–Quaternary), and Recent Kurile-Kamchatka systems. The Kamchatka volcanic belts are viewed as the products of these systems, which originated above the subduction zones. The geometry of the present-day Kurile-Kamchatka subduction zone and dynamics of contemporary volcanism can be defined from seismic data. The contemporary Kurile-Kamchatka arc can be subdivided into individual segments in accord with its tectonic evolution and geodynamics. The East Kamchatka segment represents the initial subduction stage (7–10 Ma ago) of the Pacific Plate. The Petropavlovsk segment (the Malka-Petropavlovsk zone of transverse faults) is a zone of discordant superposition of the contemporary Kurile-Kamchatka arc over the older Mid-Kamchatka arc. Within the South Kamchatka segment subduction remained practically unchanged since the Late Oligocene, i.e., since the origin of the Mid-Kamchatka-Kurile arc system, as well as within the three Kurile segments. Geodynamics controlled magma genera tion and is imprinted in the petrochemical properties of the volcanic rocks. Typical arc magmas are generated at the steady-state geodynamic regime of subduction. Lavas of an intraplate geochemical type are generated at initial and final stages of subduction, and also at the Kamchatka-Aleutian junction

Interference structure of above-threshold ionization versus above-threshold detachment

Laser-induced electron detachment or ionization of atoms and negative ions is considered. In the context of the saddle-point evaluation of the strong-field approximation (SFA), the velocity maps of the direct electrons (those that do not undergo rescattering) exhibit a characteristic structure due to the constructive and destructive interference of electrons liberated from their parent atoms/ions within certain windows of time. This structure is defined by the above-threshold ionization rings at fixed electron energy and by two sets of curves in momentum space on which destructive interference occurs. The spectra obtained with the SFA are compared with those obtained by numerical solution of the time-dependent Schrödinger equation. For detachment, the agreement is excellent. For ionization, the effect of the Coulomb field is most pronounced for electrons emitted in a direction close to laser polarization, while for nearperpendicular emission the qualitative appearance of the spectrum is unaffected

Strong field approximation within a Faddeev-like formalism for laser-matter interactions

We consider the interaction of atomic hydrogen with an intense laser field within the strong-field approximation. By using a Faddeev-like formalism, we introduce a new perturbative series in the binding potential of the atom. As a first test of this new approach, we calculate the electron energy spectrum in the very simple case of a photon energy higher than the ionisation potential. We show that by contrast to the standard perturbative series in the binding potential obtained within the strong field approximation, the first terms of the new series converge rapidly towards the results we get by solving the corresponding time-dependent Schroedinger equation.Comment: 7 pages, 1 figur

Quantum effects on radiation friction driven magnetic field generation

Radiation losses in the interaction of superintense circularly polarized laser pulses with high-density plasmas can lead to the generation of strong quasistatic magnetic fields via absorption of the photon angular momentum (so-called inverse Faraday effect). To achieve the magnetic field strength of several Giga Gauss, laser intensities ≃1024W/cm2 are required which brings the interaction to the border between the classical and the quantum regimes. We improve the classical modeling of the laser interaction with overcritical plasma in the “hole boring” regime by using a modified radiation friction force accounting for quantum recoil and spectral cut-off at high energies. The results of analytical calculations and three-dimensional particle-in-cell simulations show that, in foreseeable scenarios, the quantum effects may lead to a decrease in the conversion rate of laser radiation into high-energy photons by a factor 2–3. The magnetic field amplitude is suppressed accordingly, and the magnetic field energy—by more than one order in magnitude. This quantum suppression is shown to reach a maximum at a certain value of intensity and does not grow with the further increase in intensities. The non-monotonic behavior of the quantum suppression factor results from the joint effect of the longitudinal plasma acceleration and the radiation reaction force. The predicted features could serve as a suitable diagnostic for radiation friction theories. © 2021, The Author(s)

Coulomb repulsion and quantum-classical correspondence in laser-induced nonsequential double ionization.

The influence of electron-electron Coulomb repulsion on nonsequential double ionization of rare-gas atoms is investigated. Several variants of the quantum-mechanical transition amplitude are evaluated that differ by the form of the inelastic electron-ion rescattering and whether or not Coulomb repulsion between the two electrons in the final state is included. For high laser intensity, an entirely classical model is formulated that simulates the rescattering scenario

Time-resolved holography with photoelectrons

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Suicidality in Obsessive-Compulsive Disorder: Prevalence and Relation to Symptom Dimensions and Comorbid Conditions

Background: Suicidal thoughts and behaviors, also known as suicidality, are a fairly neglected area of study in patients with obsessive-compulsive disorder (OCD). Objective: To evaluate several aspects of suicidality in a large multicenter sample of OCD patients and to compare those with and without suicidal ideation, plans, and attempts according to demographic and clinical variables, including symptom dimensions and comorbid disorders. Method: This cross-sectional study included 582 outpatients with primary OCD (DSM-IV) recruited between August 2003 and March 2008 from 7 centers of the Brazilian Research Consortium on Obsessive-Compulsive Spectrum Disorders. The following assessment instruments were used: the Yale-Brown Obsessive Compulsive Scale, the Dimensional Yale-Brown Obsessive Compulsive Scale, the Beck Depression and Anxiety Inventories, the Structured Clinical Interview for DSM-IV Axis I Disorders, and 6 specific questions to investigate suicidality. After univariate analyses, logistic regression analyses were performed to adjust the associations between the dependent and explanatory variables for possible confounders. Results: Thirty-six percent of the patients reported lifetime suicidal thoughts, 20% had made suicidal plans, 11% had already attempted suicide, and 10% presented current suicidal thoughts. In the logistic regression, only lifetime major depressive disorder and posttraumatic stress disorder (PTSD) remained independently associated with all aspects of suicidal behaviors. The sexual/religious dimension and comorbid substance use disorders remained associated with suicidal thoughts and plans, while impulse-control disorders were associated with current suicidal thoughts and with suicide plans and attempts. Conclusions: The risk of suicidal behaviors must be carefully investigated in OCD patients, particularly those with symptoms of the sexual/religious dimension and comorbid major depressive disorder, PTSD, substance use disorders, and impulse-control disorders. J Clin Psychiatry 2011;72(1):17-26 (C) Copyright 2011 Physicians Postgraduate Press, Inc.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[2005/55628-8]Conselho Nacional de Desenvolvimento Cientifico e Tecnolngico (CNPQ)[573974/2008-0