833 research outputs found
Inflammatory and Oxidative Stress Responses to High-Carbohydrate and High-Fat Meals in Healthy Humans
The postprandial state is hypothesised to be proinflammatory and prooxidative, but the relative contributions of fat versus carbohydrate are unclear. Therefore, we examined inflammation and oxidative stress responses in serum and skeletal muscle before and after 1000 kcal meals, which were high in either fat or carbohydrate in 15 healthy individuals. Serum and muscle expression of IL6 was elevated 3 hours after each meal, independently of macronutrient composition (P < 0.01). Serum IL18 was decreased after high-fat meal only (P < 0.01). Plasma total antioxidative status and muscle Cu/Zn-superoxide dismutase were decreased after high-carbohydrate meal only (P < 0.05). We conclude that a high-carbohydrate meal may evoke a greater postprandial oxidative stress response, whereas both fat and carbohydrate increased IL6. We speculate that the observed increases in postprandial IL6, without increases in any other markers of inflammation, may indicate a normal IL6 response to enhance glucose uptake, similar to its role postexercise
Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet Sun region
High-resolution observations of a quiet Sun internetwork region taken with
the Solar 1-m Swedish Telescope in La Palma are analyzed. We determine the
location of small-scale vortex motions in the solar photospheric region by
computing the horizontal proper motions of small-scale structures on time
series of images. These plasma convectively-driven swirl motions are associated
to: (1) downdrafts (that have been commonly explained as corresponding to sites
where the plasma is cooled down and hence returned to the interior below the
visible photospheric level), and (2) horizontal velocity vectors converging
into a central point. The sink cores are proved to be the final destination of
passive floats tracing plasma flows towards the center of each vortex. We
establish the occurrence of these events to be 1.4 x 10^(-3) and 1.6 x 10^(-3)
vortices Mm^(-2) min^(-1) respectively for two time series analyzed here.Comment: 8 pages, 6 figures. Accepted for publication in Monthly Notices of
the Royal Astronomical Societ
On the Moat-Penumbra Relation
Proper motions in a sunspot group with a delta-configuration and close to the
solar disc center have been studied by employing local correlation tracking
techniques. The analysis is based on more than one hour time series of G-band
images. Radial outflows with a mean speed of 0.67 km s^{-1} have been detected
around the spots, the well-known sunspots moats. However, these outflows are
not found in those umbral core sides without penumbra. Moreover, moat flows are
only found in those sides of penumbrae located in the direction marked by the
penumbral filaments. Penumbral sides perpendicular to them show no moat flow.
These results strongly suggest a relation between the moat flow and the
well-known, filament aligned, Evershed flow. The standard picture of a moat
flow originated from a blocking of the upward propagation of heat is commented
in some detail.Comment: 4 pages, 4 figures, To appear in ApJ Letter
Resummed Quantum Gravity
We present the current status of the a new approach to quantum general
relativity based on the exact resummation of its perturbative series as that
series was formulated by Feynman. We show that the resummed theory is UV finite
and we present some phenomenological applications as well.Comment: 4 pages, 1 figure; presented at ICHEP0
Towards Verifying Nonlinear Integer Arithmetic
We eliminate a key roadblock to efficient verification of nonlinear integer
arithmetic using CDCL SAT solvers, by showing how to construct short resolution
proofs for many properties of the most widely used multiplier circuits. Such
short proofs were conjectured not to exist. More precisely, we give n^{O(1)}
size regular resolution proofs for arbitrary degree 2 identities on array,
diagonal, and Booth multipliers and quasipolynomial- n^{O(\log n)} size proofs
for these identities on Wallace tree multipliers.Comment: Expanded and simplified with improved result
Bright points in the quiet Sun as observed in the visible and near-UV by the balloon-borne observatory Sunrise
Bright points (BPs) are manifestations of small magnetic elements in the
solar photosphere. Their brightness contrast not only gives insight into the
thermal state of the photosphere (and chromosphere) in magnetic elements, but
also plays an important role in modulating the solar total and spectral
irradiance. Here we report on simultaneous high-resolution imaging and
spectropolarimetric observations of BPs using Sunrise balloon-borne observatory
data of the quiet Sun at disk center. BP contrasts have been measured between
214 nm and 525 nm, including the first measurements at wavelengths below 388
nm. The histograms of the BP peak brightness show a clear trend toward broader
contrast distributions and higher mean contrasts at shorter wavelengths. At 214
nm we observe a peak brightness of up to five times the mean quiet-Sun value,
the highest BP contrast so far observed. All BPs are associated with a magnetic
signal, although in a number of cases it is surprisingly weak. Most of the BPs
show only weak downflows, the mean value being 240 m/s, but some display strong
down- or upflows reaching a few km/s.Comment: Accepted for publication in The Astrophysical Journal Letters on
September 08 201
Fully resolved quiet-Sun magnetic flux tube observed with the Sunrise IMaX instrument
Until today, the small size of magnetic elements in quiet Sun areas has
required the application of indirect methods, such as the line-ratio technique
or multi-component inversions, to infer their physical properties. A consistent
match to the observed Stokes profiles could only be obtained by introducing a
magnetic filling factor that specifies the fraction of the observed pixel
filled with magnetic field. Here, we investigate the properties of a small
magnetic patch in the quiet Sun observed with the IMaX magnetograph on board
the balloon-borne telescope Sunrise with unprecedented spatial resolution and
low instrumental stray light. We apply an inversion technique based on the
numerical solution of the radiative transfer equation to retrieve the
temperature stratification and the field strength in the magnetic patch. The
observations can be well reproduced with a one-component, fully magnetized
atmosphere with a field strength exceeding 1 kG and a significantly enhanced
temperature in the mid- to upper photosphere with respect to its surroundings,
consistent with semi-empirical flux tube models for plage regions. We therefore
conclude that, within the framework of a simple atmospheric model, the IMaX
measurements resolve the observed quiet-Sun flux tube.Comment: Accepted for publication in The Astrophysical Journal Letters on Aug
11 201
Sunrise: instrument, mission, data and first results
The Sunrise balloon-borne solar observatory consists of a 1m aperture Gregory
telescope, a UV filter imager, an imaging vector polarimeter, an image
stabilization system and further infrastructure. The first science flight of
Sunrise yielded high-quality data that reveal the structure, dynamics and
evolution of solar convection, oscillations and magnetic fields at a resolution
of around 100 km in the quiet Sun. After a brief description of instruments and
data, first qualitative results are presented. In contrast to earlier
observations, we clearly see granulation at 214 nm. Images in Ca II H display
narrow, short-lived dark intergranular lanes between the bright edges of
granules. The very small-scale, mixed-polarity internetwork fields are found to
be highly dynamic. A significant increase in detectable magnetic flux is found
after phase-diversity-related reconstruction of polarization maps, indicating
that the polarities are mixed right down to the spatial resolution limit, and
probably beyond.Comment: accepted by ApJ
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