1,471 research outputs found
On the Origin of a Sunquake during the 29 March 2014 X1 Flare
Helioseismic data from the HMI instrument have revealed a sunquake associated
with the X1 flare SOL2014-03-29T17:48 in active region NOAA 12017. We try to
discover if acoustic-like impulses or actions of the Lorentz force caused the
sunquake. We analyze spectro-polarimetric data obtained with the Facility
Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Fortuitously
the FIRS slit crossed the flare kernel close to the acoustic source, during the
impulsive phase. The infrared FIRS data remain unsaturated throughout the
flare. Stokes profiles of lines of Si I 1082.7 nm and He I 1083.0 nm are
analyzed. At the flare footpoint, the Si I 1082.7 nm core intensity increases
by a factor of several, the IR continuum increases by 4 +/- 1%. Remarkably, the
Si I core resembles the classical Ca II K line's self-reversed profile. With
nLTE radiative models of H, C, Si and Fe these properties set the penetration
depth of flare heating to 100 +/- 100 km, i.e. photospheric layers. Estimates
of the non-magnetic energy flux are at least a factor of two less than the
sunquake energy flux. Milne-Eddington inversions of the Si I line show that the
local magnetic energy changes are also too small to drive the acoustic pulse.
Our work raises several questions: Have we "missed" the signature of downward
energy propagation? Is it intermittent in time and/or non-local? Does the 1-2 s
photospheric radiative damping time discount compressive modes?Comment: in pres
A Critical Realist Reflection on the Use of Social Media as Third Space for Rights Education in Early Childhood
The promotion and advancement of Rights Education in Early Childhood ought to be supported through the development of spaces that allow for interdisciplinary discourses among different stakeholders. The project #ChildRightsChat emerged from interactions between the authors to use a digital space to promote the advancement of an interdisciplinary and global discussion about children’s rights. A primary aim was to facilitate adult learning about the protection and promotion of children’s rights in practice. Chats in Twitter, through structured and moderated interactions, were designed to share knowledge and experiences around specific topics. The present paper presents the authors’ reflections, as moderators of #ChildRightsChat, through a critical realist analysis. The findings explore how social media can be understood as a learning environment in ‘third space’, with respect to the nature of interactions that occurred, the context as a learning space, and the voices heard in the chat. The implications of social media to include global perspectives for the advancement of rights-based practice in early childhood education and care are considered
Qubits entanglement dynamics modified by an effective atomic environment
We study entanglement dynamics of a couple of two-level atoms resonantly
interacting with a cavity mode and embedded in a dispersive atomic environment.
We show that in the absence of the environment the entanglement reaches its
maximum value when only one exitation is involved. Then, we find that the
atomic environment modifies that entanglement dynamics and induces a typical
collapse-revival structure even for an initial one photon Fock state of the
field.Comment: eight pages, two figure include
Derivation of Instrument Requirements for Polarimetry using Mg, Fe, and Mn lines between 250 and 290 nm
Judge et al. (2021) recently argued that a region of the solar spectrum in
the near-UV between about 250 and 290 nm is optimal for studying magnetism in
the solar chromosphere due to an abundance of Mg II, Fe II, and Fe I lines that
sample various heights in the solar atmosphere. In this paper we derive
requirements for spectropolarimetric instruments to observe these lines. We
derive a relationship between the desired sensitivity to magnetic field and the
signal-to-noise of the measurement from the weak-field approximation of the
Zeeman effect. We find that many lines will exhibit observable polarization
signals for both longitudinal and transverse magnetic field with reasonable
amplitudes
A review of canine babesiosis: The European perspective
Canine babesiosis is a significant tick-borne disease caused by various species of the protozoan genus Babesia. Although it occurs worldwide, data relating to European infections have now been collected for many years. These data have boosted the publication record and increased our working knowledge of these protozoan parasites. Both the large and small forms of Babesia species (B. canis, B. vogeli, B. gibsoni, and B. microti-like isolates also referred to as "B. vulpes" and "Theileria annae") infect dogs in Europe, and their geographical distribution, transmission, clinical signs, treatment, and prognosis vary widely for each species. The goal of this review is to provide veterinary practitioners with practical guidelines for the diagnosis, treatment and prevention of babesiosis in European dogs. Our hope is that these guidelines will answer the most frequently asked questions posed by veterinary practitioners
Scattering polarization of hydrogen lines in the presence of turbulent electric fields
We study the broadband polarization of hydrogen lines produced by scattering
of radiation, in the presence of isotropic electric fields. In this paper, we
focus on two distinct problems: a) the possibility of detecting the presence of
turbulent electric fields by polarimetric methods, and b) the influence of such
fields on the polarization due to a macroscopic, deterministic magnetic field.
We found that isotropic electric fields decrease the degree of linear
polarization in the scattered radiation, with respect to the zero-field case.
On the other hand, a distribution of isotropic electric fields superimposed
onto a deterministic magnetic field can generate a significant increase of the
degree of magnetic-induced, net circular polarization. This phenomenon has
important implications for the diagnostics of magnetic fields in plasmas using
hydrogen lines, because of the ubiquitous presence of the Holtsmark,
microscopic electric field from neighbouring ions. In particular, previous
solar magnetographic studies of the Balmer lines of hydrogen may need to be
revised because they neglected the effect of turbulent electric fields on the
polarization signals. In this work, we give explicit results for the
Lyman-alpha and Balmer-alpha lines.Comment: 15 pages, 6 figure
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