651 research outputs found
Findings of Fahr’s Syndrome in A Patient Suspected With Subarachnoid Hemorrhage: An Evidence-Based Case Report
ABSTRACT
Fahr’s syndrome is an entity where there is symmetrical bilateral calcification of basal ganglia with parkinsonian and psychiatric symptoms. However, due to its rarity, clinicians tend not to include Fahr’s syndrome in their differential diagnosis. This article aims to raise awareness about the diagnosis of Fahr’s Syndrome through its unique presentation in this patient. Data was obtained primarily and secondarily. In this case, a 32 years old male was referred to our clinic with chief complaints of headache since a week prior and a seizure 5 days ago. A head CT and a CT angiography (CTA) of the circulus willisi were done and a bilateral and symmetrical calcification of the corona radiata, basal ganglia, thalamus, and nucleus dentatus were found. There is also hypocalcemia and low Parathyroid Hormone (PTH). Fahr’s Syndrome may manifest unusually and hence clinicians have to be aware of diagnosing this entity.
Keywords: Fahr’s Disease, Fahr’s Syndrome
ABSTRAK
Sindroma Fahr’s merupakan sebuah penyakit yang ditandai dengan kalsifikasi bilateral sietris dari basal ganglia dengan gejala psikatri dan parkinsonisme. Namun, akibat jarangnya ditemukan penyakit ini, klinisi cenderung tidak memikirkan sindroma Fahr’s sebagai salah satu diagnosis banding. Artikel ini bertujuan untuk meningkatkan kewaspadaan terhadap diagnosis Sindroma Fahr’s melalui presentasi unik pada pasien ini. Data diambil secara primer dan sekunder. Pada kasus ini, seorang laki-laki berusia 32 tahun dirujuk dengan keluhan utama sakit kepala sejak satu minggu dan kejang 5 hari sebelum masuk rumah sakit. Computed Tomography (CT) scan kepala dan Computed Tomography Angiography (CTA) dari sirkulus willisi dilakukan dan ditemukan adanya kalsifikasi bilateral simetris pada korona radiata, basal ganglia, talamus dan nukleus dentatus. Pada pemeriksaan laboratorium ditemukan adanya hipokalsemia dan hormon paratiroid (PTH) yang rendah. Sindroma Fahr’s dapat datang dengan presentasi yang tidak khas sehingga para klinisi harus lebih tajam dalam mendiagnosis kasus ini.
Kata kunci: Penyakit Fahr’s, Sindroma Fahr’
Automatic detection of limb prominences in 304 A EUV images
A new algorithm for automatic detection of prominences on the solar limb in 304 A EUV images is presented, and results of its application to SOHO/EIT data discussed. The detection is based on the method of moments combined with a
classifier analysis aimed at discriminating between limb prominences, active regions, and the quiet corona. This classifier analysis is based on a Support Vector Machine (SVM). Using a set of 12 moments of the radial intensity profiles, the algorithm performs well in discriminating between the above three categories of limb structures, with a misclassification rate of 7%. Pixels detected as belonging to a prominence are then used as starting point to reconstruct the whole prominence by morphological image processing techniques. It is planned that a catalogue of limb prominences identified in SOHO and STEREO data using this method will be made publicly available to the scientific community
Coronal Shock Waves, EUV waves, and their Relation to CMEs. II. Modeling MHD Shock Wave Propagation Along the Solar Surface, Using Nonlinear Geometrical Acoustics
We model the propagation of a coronal shock wave, using nonlinear geometrical
acoustics. The method is based on the Wentzel-Kramers-Brillouin (WKB) approach
and takes into account the main properties of nonlinear waves: i) dependence of
the wave front velocity on the wave amplitude, ii) nonlinear dissipation of the
wave energy, and iii) progressive increase in the duration of solitary shock
waves. We address the method in detail and present results of the modeling of
the propagation of shock-associated extreme-ultraviolet (EUV) waves as well as
Moreton waves along the solar surface in the simplest solar corona model. The
calculations reveal deceleration and lengthening of the waves. In contrast,
waves considered in the linear approximation keep their length unchanged and
slightly accelerate.Comment: 15 pages, 7 figures, accepted for publication in Solar Physic
Large-scale Bright Fronts in the Solar Corona: A Review of "EIT waves"
``EIT waves" are large-scale coronal bright fronts (CBFs) that were first
observed in 195 \AA\ images obtained using the Extreme-ultraviolet Imaging
Telescope (EIT) onboard the \emph{Solar and Heliospheric Observatory (SOHO)}.
Commonly called ``EIT waves", CBFs typically appear as diffuse fronts that
propagate pseudo-radially across the solar disk at velocities of 100--700 km
s with front widths of 50-100 Mm. As their speed is greater than the
quiet coronal sound speed (200 km s) and comparable to the
local Alfv\'{e}n speed (1000 km s), they were initially
interpreted as fast-mode magnetoacoustic waves ().
Their propagation is now known to be modified by regions where the magnetosonic
sound speed varies, such as active regions and coronal holes, but there is also
evidence for stationary CBFs at coronal hole boundaries. The latter has led to
the suggestion that they may be a manifestation of a processes such as Joule
heating or magnetic reconnection, rather than a wave-related phenomena. While
the general morphological and kinematic properties of CBFs and their
association with coronal mass ejections have now been well described, there are
many questions regarding their excitation and propagation. In particular, the
theoretical interpretation of these enigmatic events as magnetohydrodynamic
waves or due to changes in magnetic topology remains the topic of much debate.Comment: 34 pages, 19 figure
On the structure and evolution of a polar crown prominence/filament system
Polar crown prominences are made of chromospheric plasma partially circling
the Suns poles between 60 and 70 degree latitude. We aim to diagnose the 3D
dynamics of a polar crown prominence using high cadence EUV images from the
Solar Dynamics Observatory (SDO)/AIA at 304 and 171A and the Ahead spacecraft
of the Solar Terrestrial Relations Observatory (STEREO-A)/EUVI at 195A. Using
time series across specific structures we compare flows across the disk in 195A
with the prominence dynamics seen on the limb. The densest prominence material
forms vertical columns which are separated by many tens of Mm and connected by
dynamic bridges of plasma that are clearly visible in 304/171A two-color
images. We also observe intermittent but repetitious flows with velocity 15
km/s in the prominence that appear to be associated with EUV bright points on
the solar disk. The boundary between the prominence and the overlying cavity
appears as a sharp edge. We discuss the structure of the coronal cavity seen
both above and around the prominence. SDO/HMI and GONG magnetograms are used to
infer the underlying magnetic topology. The evolution and structure of the
prominence with respect to the magnetic field seems to agree with the filament
linkage model.Comment: 24 pages, 14 figures, Accepted for publication in Solar Physics
Journal, Movies can be found at http://www2.mps.mpg.de/data/outgoing/panesar
The Non-linear Dynamics of Meaning-Processing in Social Systems
Social order cannot be considered as a stable phenomenon because it contains
an order of reproduced expectations. When the expectations operate upon one
another, they generate a non-linear dynamics that processes meaning. Specific
meaning can be stabilized, for example, in social institutions, but all meaning
arises from a horizon of possible meanings. Using Luhmann's (1984) social
systems theory and Rosen's (1985) theory of anticipatory systems, I submit
equations for modeling the processing of meaning in inter-human communication.
First, a self-referential system can use a model of itself for the
anticipation. Under the condition of functional differentiation, the social
system can be expected to entertain a set of models; each model can also
contain a model of the other models. Two anticipatory mechanisms are then
possible: one transversal between the models, and a longitudinal one providing
the modeled systems with meaning from the perspective of hindsight. A system
containing two anticipatory mechanisms can become hyper-incursive. Without
making decisions, however, a hyper-incursive system would be overloaded with
uncertainty. Under this pressure, informed decisions tend to replace the
"natural preferences" of agents and an order of cultural expectations can
increasingly be shaped
Physics of Solar Prominences: I - Spectral Diagnostics and Non-LTE Modelling
This review paper outlines background information and covers recent advances
made via the analysis of spectra and images of prominence plasma and the
increased sophistication of non-LTE (ie when there is a departure from Local
Thermodynamic Equilibrium) radiative transfer models. We first describe the
spectral inversion techniques that have been used to infer the plasma
parameters important for the general properties of the prominence plasma in
both its cool core and the hotter prominence-corona transition region. We also
review studies devoted to the observation of bulk motions of the prominence
plasma and to the determination of prominence mass. However, a simple inversion
of spectroscopic data usually fails when the lines become optically thick at
certain wavelengths. Therefore, complex non-LTE models become necessary. We
thus present the basics of non-LTE radiative transfer theory and the associated
multi-level radiative transfer problems. The main results of one- and
two-dimensional models of the prominences and their fine-structures are
presented. We then discuss the energy balance in various prominence models.
Finally, we outline the outstanding observational and theoretical questions,
and the directions for future progress in our understanding of solar
prominences.Comment: 96 pages, 37 figures, Space Science Reviews. Some figures may have a
better resolution in the published version. New version reflects minor
changes brought after proof editin
Physics of Solar Prominences: II - Magnetic Structure and Dynamics
Observations and models of solar prominences are reviewed. We focus on
non-eruptive prominences, and describe recent progress in four areas of
prominence research: (1) magnetic structure deduced from observations and
models, (2) the dynamics of prominence plasmas (formation and flows), (3)
Magneto-hydrodynamic (MHD) waves in prominences and (4) the formation and
large-scale patterns of the filament channels in which prominences are located.
Finally, several outstanding issues in prominence research are discussed, along
with observations and models required to resolve them.Comment: 75 pages, 31 pictures, review pape
What is the Nature of EUV Waves? First STEREO 3D Observations and Comparison with Theoretical Models
One of the major discoveries of the Extreme ultraviolet Imaging Telescope
(EIT) on SOHO were intensity enhancements propagating over a large fraction of
the solar surface. The physical origin(s) of the so-called `EIT' waves is still
strongly debated. They are considered to be either wave (primarily fast-mode
MHD waves) or non-wave (pseudo-wave) interpretations. The difficulty in
understanding the nature of EUV waves lies with the limitations of the EIT
observations which have been used almost exclusively for their study. Their
limitations are largely overcome by the SECCHI/EUVI observations on-board the
STEREO mission. The EUVI telescopes provide high cadence, simultaneous
multi-temperature coverage, and two well-separated viewpoints. We present here
the first detailed analysis of an EUV wave observed by the EUVI disk imagers on
December 07, 2007 when the STEREO spacecraft separation was .
Both a small flare and a CME were associated with the wave cadence, and single
temperature and viewpoint coverage. These limitations are largely overcome by
the SECCHI/EUVI observations on-board the STEREO mission. The EUVI telescopes
provide high cadence, simultaneous multi-temperature coverage, and two
well-separated viewpoints. Our findings give significant support for a
fast-mode interpretation of EUV waves and indicate that they are probably
triggered by the rapid expansion of the loops associated with the CME.Comment: Solar Physics, 2009, Special STEREO Issue, in pres
Characteristics of EUV coronal jets observed with STEREO/SECCHI
In this paper we present the first comprehensive statistical study of EUV
coronal jets observed with the SECCHI imaging suites of the two STEREO
spacecraft. A catalogue of 79 polar jets is presented, identified from
simultaneous EUV and white-light coronagraph observations, taken during the
time period March 2007 to April 2008. The appearances of the coronal jets were
always correlated with underlying small-scale chromospheric bright points. A
basic characterisation of the morphology and identification of the presence of
helical structure were established with respect to recently proposed models for
their origin and temporal evolution. A classification of the events with
respect to previous jet studies shows that amongst the 79 events there were 37
Eiffel tower-type jet events commonly interpreted as a small-scale (about 35
arcsec) magnetic bipole reconnecting with the ambient unipolar open coronal
magnetic fields at its looptops, and 12 lambda-type jet events commonly
interpreted as reconnection with the ambient field happening at the bipoles
footpoints. Five events were termed micro-CME type jet events because they
resembled the classical coronal mass ejections (CMEs) but on much smaller
scales. A few jets are also found in equatorial coronal holes. The typical
lifetimes in the SECCHI/EUVI (Extreme UltraViolet Imager) field of view between
1.0 to 1.7 solar radius and in SECCHI/COR1 field of view between 1.4 to 4 solar
radius are obtained, and the derived speed are roughly estimated. In summary,
the observations support the assumption of continuous small-scale reconnection
as an intrinsic feature of the solar corona, with its role for the heating of
the corona, particle acceleration, structuring and acceleration of the solar
wind remaining to be explored in more details in further studies.Comment: 20 pages, 7 tables of figures, 2 tables of plots, an appendix with
list event
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