634 research outputs found
Coronal Mass Ejections Associated with Slow Long Duration Flares
It is well known that there is temporal relationship between coronal mass
ejections (CMEs) and associated flares. The duration of the acceleration phase
is related to the duration of the rise phase of a flare. We investigate CMEs
associated with slow long duration events (LDEs), i.e. flares with the long
rising phase. We determined the relationships between flares and CMEs and
analyzed the CME kinematics in detail. The parameters of the flares (GOES flux,
duration of the rising phase) show strong correlations with the CME parameters
(velocity, acceleration during main acceleration phase and duration of the CME
acceleration phase). These correlations confirm the strong relation between
slow LDEs and CMEs. We also analyzed the relation between the parameters of the
CMEs, i.e. a velocity, an acceleration during the main acceleration phase, a
duration of the acceleration phase, and a height of a CME at the end of the
acceleration phase. The CMEs associated with the slow LDEs are characterized by
high velocity during the propagation phase, with the median equal 1423 km/s. In
half of the analyzed cases, the main acceleration was low (a<300 m/s^2), which
suggests that the high velocity is caused by the prolongated acceleration phase
(the median for the duration of the acceleration phase is equal 90 minutes).
The CMEs were accelerated up to several solar radii (with the median 7 Rsun),
which is much higher than in typical impulsive CMEs. Therefore, slow LDEs may
potentially precede extremely strong geomagnetic storms. The analysis of slow
LDEs and associated CMEs may give important information for developing more
accurate space weather forecasts, especially for extreme events.Comment: Solar Physics, accepte
EUV and HXR Signatures of Electron Acceleration During the Failed Eruption of a Filament
We search for EUV brightenings in TRACE 171 {\AA} images and HXR bursts
observed during failed eruptions. We expect that if an eruption is confined due
to interaction with overlying magnetic structures then we should observe
effects connected with reconnection between magnetic structures and
acceleration of particles. We utilized TRACE observations of three well
observed failed eruptions. EUV images were compared to HXR spatial distribution
reconstructed from Yohkoh/HXT and RHESSI data. The EUV light curves of a
selected area were compared to height profiles of eruption, HXR emission and
HXR photon spectral index of power-law fit to HXR data. We have found that EUV
brightenings are closely related to the eruption velocity decrease, to HXR
bursts and to episodes of hardening of HXR spectra. The EUV brightened areas
are observed far from the flaring structure, in footpoints of large systems of
loops observed 30-60 minutes after the maximum of a flare. These are not
`post-flare' loops that are also observed but at significantly lower heights.
The high lying systems of loops are observed at heights equal to height, at
which eruption was observed to stop. We observed HXR source spatially
correlated with EUV brightening only once. For other EUV brightened areas we
estimated the expected brightness of HXR sources. We find that EUV brightenings
are produced due to interaction between the erupting structure with overlying
loops. The interaction is strong enough to heat the system of high loops. These
loops cool down and are visible in EUV range about 30-60 minutes later. The
estimated brightness of HXR sources associated with EUV brightenings shows that
they are too weak to be detected with present instruments. However, next
generation instruments will have enough dynamic range and sensitivity to enable
such observations.Comment: A&A accepte
Coherent population oscillations with nitrogen-vacancy color centers in diamond
We present results of our research on two-field (two-frequency) microwave
spectroscopy in nitrogen-vacancy (NV-) color centers in a diamond. Both fields
are tuned to transitions between the spin sublevels of the NV- ensemble in the
3A2 ground state (one field has a fixed frequency while the second one is
scanned). Particular attention is focused on the case where two microwaves
fields drive the same transition between two NV- ground state sublevels (ms=0
-> ms=+1). In this case, the observed spectra exhibit a complex narrow
structure composed of three Lorentzian resonances positioned at the pump-field
frequency. The resonance widths and amplitudes depend on the lifetimes of the
levels involved in the transition. We attribute the spectra to coherent
population oscillations induced by the two nearly degenerate microwave fields,
which we have also observed in real time. The observations agree well with a
theoretical model and can be useful for investigation of the NV relaxation
mechanisms.Comment: 17 page
Лексическое наполнение современных газет российских немцев как реализация этнической функции языка
The purpose of our study was to determine the expression of the pro-apoptotic BAX protein in relation to the mutational status of BAX and p53 (as transcriptional activator of the BAX gene) in benign and malignant thyroid tissue. In 47 patients with thyroid tumours (14 follicular and 3 papillary carcinomas, 14 adenomas and 16 goitres), the DNA was screened for mutations of BAX (exon 1-6) and p53 (exon 5-8) by single-strand conformation polymorphism polymerase chain reaction (SSCP-PCR). Furthermore, the protein expression of BAX, p53 and p21 (which is also increased transcriptionally by p53) was investigated by immunohistochemistry. Surprisingly, we observed elevated BAX levels in patients with thyroid carcinomas compared with patients with adenomas (unpaired t-test: p<0.05) or with goitres (p<0.02). This is in clear contrast to other carcinomas where BAX is frequently inactivated which correlates to a poor prognosis (Sturm et al., 1999). There were no significant differences of the BAX levels between goitres or the adenomas. In the SSCP-PCR analysis, no BAX mutations were detectable. P53 mutation analysis by SSCP-PCR did not reveal any functional p53 mutations in the patients with carcinomas, adenomas or goitres. Nevertheless, patients with carcinomas showed an overexpression (preferentially cytoplasmic) of p53 protein compared with patients with benign tumours (p<0.05). The absence of p53 mutations suggests that the overexpressed p53 is wild type. This is in line with the expression profile of BAX and p21, which showed a higher protein expression in these p53 positive tumours (p<0.05 in the carcinomas compared with the non-malignant lesions). Consequently, the overexpressed p53 might be a correlate for dysregulation without loss of function. This, in turn, might be a reason for the good outcome of some patients with thyroid cancer
Structure of the Afferent Terminals in Terminal Ganglion of a Cricket and Persistent Homology
We use topological data analysis to investigate the three dimensional spatial structure of the locus of afferent neuron terminals in crickets Acheta domesticus. Each afferent neuron innervates a filiform hair positioned on a cercus: a protruding appendage at the rear of the animal. The hairs transduce air motion to the neuron signal that is used by a cricket to respond to the environment. We stratify the hairs (and the corresponding afferent terminals) into classes depending on hair length, along with position. Our analysis uncovers significant structure in the relative position of these terminal classes and suggests the functional relevance of this structure. Our method is very robust to the presence of significant experimental and developmental noise. It can be used to analyze a wide range of other point cloud data sets
Identification of transplanted pancreatic islet cells by radioactive Dithizone-[131I]-Histamine conjugate. Preliminary report
Background: The unique mechanism of dithizone action in the interior of the viable pancreatic islet suggests the possible development of a specific radiopharmaceutical that may have a potential clinical application in the diagnosis of the pancreatic organ allografts or islets rejection.
The radiodiagnostic properties of the newly developed radioactive analogue of dithizone, i.e. Dithizone-[131I]-Histamine conjugate have been evaluated in the present study.
METHODS: The four islet cells transplantation models were chosen for this purpose.
The most important feature of the Dithizone-[131I]-Histamine conjugate is its possessed ability of zinc chelation. As was presented in the recent study, the conjugate stains pink-reddish the isolated pancreatic islets in vitro. Among the studied transplantation models, only the islets grafting under testis capsule enabled determination of the pancreatic islets in rats by radioactive Dithizone-[131I]-Histamine conjugate. The level of the radioactivity in the recipient testis (right) was almost two times higher compared to the controls (0.24 vs. 0.13% ID/g, respectively).
CONCLUSIONS:These preliminary data demonstrate the ability of the developed radioactive analogue of dithizone for in vivo identification of transplanted pancreatic islets, and suggests a potential clinical application of the radiodithizone in the diagnosis of the pancreatic islet rejection
What is the impact of physical effort on the diagnosis of concussion?
Objective:
Sport-related concussion commonly occurs in contact sports such as rugby. To date, diagnosis is based on the realization of clinical tests conducted pitch-side. Yet, the potential effect of prior physical effort on the results of these tests remains poorly understood. The purpose of this study was to determine whether preceding physical effort can influence the outcome of concussion assessments.
Design:
Prospective observational study.
Setting:
University Medicine Center
Patients:
A cohort of 40 subjects (20 rugby players and 20 athletes from a range of sports).
Intervention:
A concussion assessment was performed immediately following physical activity. Following a period of 6 months and under the same experimental conditions, the same cohort performed the same tests in resting conditions.
Main outcome measure:
Results of concussion tests.
Results:
In both cohorts, the comparison for post-exercise and rest assessments demonstrated a most likely moderate-to-very large increase in the number of symptoms, severity of symptoms and BESS score. In the rugby cohort, scores for concentration, delayed memory and SAC, likely-to-most likely decreased following completion of physical activity compared to baseline values. The between-cohort comparison showed a greater impact post-exercise in the rugby players for delayed recall (0.73±0.61, 93/7/1) and SAC score (0.75±0.41, 98/2/0).
Conclusion:
Physical activity altered the results of concussion diagnostic tests in athletes from a range of sports and notably in rugby players. Therefore, physical efforts prior to the concussion incident should be accounted for during pitch-side assessments and particularly during rugby competition and training
On the full, strongly exceptional collections on toric varieties with Picard number three
We investigate full strongly exceptional collections on smooth, com- plete
toric varieties. We obtain explicit results for a large family of varieties
with Picard number three, containing many of the families already known. We
also describe the relations between the collections and the split of the push
forward of the trivial line bundle by the toric Frobenius morphism
Energy Release During Slow Long Duration Flares Observed by RHESSI
Slow Long Duration Events (SLDEs) are flares characterized by long duration
of rising phase. In many such cases impulsive phase is weak with lack of
typical short-lasting pulses. Instead of that smooth, long-lasting Hard X-ray
(HXR) emission is observed. We analysed hard X-ray emission and morphology of
six selected SLDEs. In our analysis we utilized data from RHESSI and GOES
satellites. Physical parameters of HXR sources were obtained from imaging
spectroscopy and were used for the energy balance analysis. Characteristic time
of heating rate decrease, after reaching its maximum value, is very long, which
explains long rising phase of these flares.Comment: Accepted for publication in Solar Physic
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