379 research outputs found
Variation of fluxes of RR Tel emission lines measured in 2000 with respect to 1996
The aim of this work is to make available unpublished non-Fe+ emission line
fluxes from optical spectra of the symbiotic nova RR Tel which were taken in
2000, and to compare them with fluxes of the same lines from spectra taken in
1996. After leaving out blends and misidentifications, as well as the
unreliable far-red and violet lines, we present the log (F2000/F1996) flux
ratios for identified non-Fe+ lines. Mean values of log (F2000/F1996) for
different ionization potential ranges of the ions producing the lines are shown
separately for the permitted and forbidden lines. All means show fading, which
is larger in the lowest range of ionization potential. Provisional
interpretations are suggested. We also measured the values of FWHM in 2000; the
previously known decrease with time of FWHM of lines due to the same ion has
continued.Comment: 16 pages, 5 figure
The effect of dust obscuration in RR Tel on optical and IR long-term photometry and Fe II emission lines
Infrared and optical photometric and spectroscopic observations of the
symbiotic nova RR Tel are used to study the effects and properties of dust in
symbiotic binaries containing a cool Mira component, as well as showing
"obscuration events" of increased absorption, which are typical for such Miras.
A set of photometric observations of the symbiotic nova RR Tel in different
wavelength bands - visual from 1949 to 2002 and near-infrared (JHKL) from 1975
to 2002 - are presented. The variability due to the normal Mira pulsation was
removed from the JHKL data, which were then compared with the AAVSO visual
light curve. The changes of the Fe II emission line fluxes during the 1996-2000
obscuration episode were studied in the optical spectra taken with the
Anglo-Australian telescope.
We discuss the three periods during which the Mira component was heavily
obscured by dust as observed in the different wavelength bands. A change in the
correlations of J with other infrared magnitudes was observed with the colour
becoming redder after JD2446000. Generally, J-K was comparable, while K-L was
larger than typical values for single Miras. A distance estimate of 2.5 kpc,
based on the IR data, is given. A larger flux decrease for the permitted than
for the forbidden Fe II lines, during the obscuration episode studied, has been
found. There is no evidence for other correlations with line properties, in
particular with wavelength, which suggests obscuration due to separate
optically thick clouds in the outer layers.Comment: 19 pages, 11 figures, 3 table
Gene expression profiling suggests that complement activation is important for blister formation in bullous pemphigoid
Analysis of the circumstellar environment of the B[e] star HD 45677 (FS CMa)
We studied the circumstellar environment of the B[e] star HD 45677 through
the analysis of the emission lines from ionized metals. We used the statistical
approach of the self absorption curve method (SAC) to derive physical
parameters of the line emitting region. The Fe II and Cr II double-peaked
emission line structure is explained by the presence of a thin absorption
component red shifted by ~3 km/s. This absorption component can be interpreted
geometricaly as being due to infalling material perpendicularly to the disk
seen nearly pole-on, as indicated by the emission line structure. The Cr II and
Fe II emission lines have a complex structure with two (narrow and broad)
components, of 45 and 180 km/s FWHM for the permitted lines and 25 and 100 km/s
FWHM for the forbidden ones, respectively. We argue that the narrow components
are principaly emitted by an optically thin disk seen nearly pole-on, in a
region whose minimum radius is estimated to be 4 10^12 cm, while the broad ones
are formed in a disk-linked wind.Comment: 14 pages, submitted to Astronomy and Astrophysic
Study of blood perfusion with patent blue staining method in LPB fibrosarcoma tumors in immuno-competent and immuno-deficient mice after electrotherapy by direct current
The prolate-to-oblate shape transition of phospholipid vesicles in response to frequency variation of an AC electric field can be explained by the dielectric anisotropy of a phospholipid bilayer
The external electric field deforms flaccid phospholipid vesicles into
spheroidal bodies, with the rotational axis aligned with its direction.
Deformation is frequency dependent: in the low frequency range (~ 1 kHz), the
deformation is typically prolate, while increasing the frequency to the 10 kHz
range changes the deformation to oblate. We attempt to explain this behaviour
with a theoretical model, based on the minimization of the total free energy of
the vesicle. The energy terms taken into account include the membrane bending
energy and the energy of the electric field. The latter is calculated from the
electric field via the Maxwell stress tensor, where the membrane is modelled as
anisotropic lossy dielectric. Vesicle deformation in response to varying
frequency is calculated numerically. Using a series expansion, we also derive a
simplified expression for the deformation, which retains the frequency
dependence of the exact expression and may provide a better substitute for the
series expansion used by Winterhalter and Helfrich, which was found to be valid
only in the limit of low frequencies. The model with the anisotropic membrane
permittivity imposes two constraints on the values of material constants:
tangential component of dielectric permittivity tensor of the phospholipid
membrane must exceed its radial component by approximately a factor of 3; and
the membrane conductivity has to be relatively high, approximately one tenth of
the conductivity of the external aqueous medium.Comment: 17 pages, 6 figures; accepted for publication in J. Phys.: Condens.
Matte
Formal descriptions of material manipulations: an exploration with cuts and shadows
Shape computation in design is never purely limited to visual aspects and ideally includes material aspects as well. The physicality of designing introduces a wide range of variables for designers to tackle within the design process. We present a simple design exercise realised in four stages where we physically manipulate perforated cardboard sheets as a case to make material variables explicit in the computation. The emphasis is on representing sensory aspects rather than easily quantifiable properties more suitable for simulations. Our explorations demonstrate the use of visual rules to represent actions, variables and form as well as how to control the variables to create new results, both desired and surprising, in materially informed ways
IgE autoantibodies in serum and skin of non-bullous and bullous pemphigoid patients
Background Non-bullous pemphigoid (NBP) is a pemphigoid variant which frequently resembles other pruritic skin diseases. In contrast with bullous pemphigoid (BP), blisters are absent. In BP, previous studies showed that IgE autoantibodies may be involved in its pathogenesis. IgE-activated mast cells, basophils and eosinophils may participate in BP by inducing pruritus and possibly blister formation, although the differential role of IgE in NBP compared with BP has not yet been described. Objective To assess IgE in serum and skin of NBP and BP patients. Methods We examined total IgE and pemphigoid-specific IgE in the serum of 68 NBP and 50 BP patients by enzyme-linked immunosorbent assay (ELISA). Sera of 25 pemphigus patients and 25 elderly patients with pruritus were included as controls. Skin biopsies of 14 NBP and 14 BP patients with the highest IgE titres to NC16A were stained for IgE by immunofluorescence techniques. Results Total IgE was elevated in 63% of NBP and 60% of BP patients, and in 20% of pemphigus controls, as well as 60% of elderly controls. IgE ELISAs were more frequently positive in BP than in NBP (NC16A 18% vs. 9%, P = 0.139; BP230 34% vs. 22%, P = 0.149). IgE ELISAs for NC16A and BP230 were positive in 8% and 20% of elderly controls, respectively, while all pemphigus controls were negative. Two of 28 biopsies (7%; one NBP, one BP) showed linear IgE along the basement membrane zone, while in most biopsies (71% NBP; 86% BP) IgE was bound to dermal cells. Conclusion Since IgE was present in the serum and skin of both NBP and BP patients, this supports IgE-dependent mechanisms common to both diseases, such as pruritus. However, it remains to be elucidated whether IgE contributes to blister formation in BP
Mercury presence and speciation in the South Atlantic Ocean along the 40°S transect
Mercury (Hg) natural biogeochemical cycle is complex and a significant portion of biological
and chemical transformation occurs in the marine environment. To better understand the presence and
abundance of Hg species in the remote ocean regions, waters of South Atlantic Ocean along 40°S parallel
were investigated during UK-GEOTRACES cruise GA10. Total mercury (THg), methylated mercury (MeHg), and
dissolved gaseous mercury (DGM) concentrations were determined. The concentrations were very low in the
range of pg/L (femtomolar). All Hg species had higher concentration in western than in eastern basin.
THg did not appear to be a useful geotracer. Elevated methylated Hg species were commonly associated
with low-oxygen water masses and occasionally with peaks of chlorophyll a, both involved with carbon
(re)cycling. The overall highest MeHg concentrations were observed in themixed layer (500m) and in the vicinity
of the Gough Island. Conversely, DGM concentrations showed distinct layering and differed between the water
masses in a nutrient-like manner. DGM was lowest at surface, indicating degassing to the atmosphere, and was
highest in the Upper Circumpolar Deep Water, where the oxygen concentration was lowest. DGM increased
also in Antarctic Bottom Water. At one station, dimethylmercury was determined and showed increase in region
with lowest oxygen saturation. Altogether, our data indicate that the South Atlantic Ocean could be a source of
Hg to the atmosphere and that its biogeochemical transformations depend primarily upon carbon cycling and
are thereby additionally prone to global ocean change
High-frequency irreversible electroporation (H-FIRE) for non-thermal ablation without muscle contraction
<p>Abstract</p> <p>Background</p> <p>Therapeutic irreversible electroporation (IRE) is an emerging technology for the non-thermal ablation of tumors. The technique involves delivering a series of unipolar electric pulses to permanently destabilize the plasma membrane of cancer cells through an increase in transmembrane potential, which leads to the development of a tissue lesion. Clinically, IRE requires the administration of paralytic agents to prevent muscle contractions during treatment that are associated with the delivery of electric pulses. This study shows that by applying high-frequency, bipolar bursts, muscle contractions can be eliminated during IRE without compromising the non-thermal mechanism of cell death.</p> <p>Methods</p> <p>A combination of analytical, numerical, and experimental techniques were performed to investigate high-frequency irreversible electroporation (H-FIRE). A theoretical model for determining transmembrane potential in response to arbitrary electric fields was used to identify optimal burst frequencies and amplitudes for <it>in vivo </it>treatments. A finite element model for predicting thermal damage based on the electric field distribution was used to design non-thermal protocols for <it>in vivo </it>experiments. H-FIRE was applied to the brain of rats, and muscle contractions were quantified via accelerometers placed at the cervicothoracic junction. MRI and histological evaluation was performed post-operatively to assess ablation.</p> <p>Results</p> <p>No visual or tactile evidence of muscle contraction was seen during H-FIRE at 250 kHz or 500 kHz, while all IRE protocols resulted in detectable muscle contractions at the cervicothoracic junction. H-FIRE produced ablative lesions in brain tissue that were characteristic in cellular morphology of non-thermal IRE treatments. Specifically, there was complete uniformity of tissue death within targeted areas, and a sharp transition zone was present between lesioned and normal brain.</p> <p>Conclusions</p> <p>H-FIRE is a feasible technique for non-thermal tissue ablation that eliminates muscle contractions seen in IRE treatments performed with unipolar electric pulses. Therefore, it has the potential to be performed clinically without the administration of paralytic agents.</p
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