5,428 research outputs found
Nanoflare Evidence from Analysis of the X-Ray Variability of an Active Region Observed with Hinode/XRT
The heating of the solar corona is one of the big questions in astrophysics.
Rapid pulses called nanoflares are among the best candidate mechanisms. The
analysis of the time variability of coronal X-ray emission is potentially a
very useful tool to detect impulsive events. We analyze the small-scale
variability of a solar active region in a high cadence Hinode/XRT observation.
The dataset allows us to detect very small deviations of emission fluctuations
from the distribution expected for a constant rate. We discuss the deviations
in the light of the pulsed-heating scenario.Comment: 6 pages, 4 figure
Widespread nanoflare variability detected with Hinode/XRT in a solar active region
It is generally agreed that small impulsive energy bursts called nanoflares
are responsible for at least some of the Sun's hot corona, but whether they are
the explanation for most of the multi-million degree plasma has been a matter
of ongoing debate. We here present evidence that nanoflares are widespread in
an active region observed by the X-Ray Telescope on-board the Hinode mission.
The distributions of intensity fluctuations have small but important
asymmetries, whether taken from individual pixels, multi-pixel subregions, or
the entire active region. Negative fluctuations (corresponding to reduced
intensity) are greater in number but weaker in amplitude, so that the median
fluctuation is negative compared to a mean of zero. Using MonteCarlo
simulations, we show that only part of this asymmetry can be explained by
Poisson photon statistics. The remainder is explainable with a tendency for
exponentially decreasing intensity, such as would be expected from a cooling
plasma produced from a nanoflare. We suggest that nanoflares are a universal
heating process within active regions.Comment: 26 pages, 7 figure
All Coronal Loops are the Same: Evidence to the Contrary
The 1998 April 20 spectral line data from the Coronal Diagnostics
Spectrometer (CDS) on the {\it Solar and Heliospheric Observatory} (\SOHO)
shows a coronal loop on the solar limb. Our original analysis of these data
showed that the plasma was multi-thermal, both along the length of the loop and
along the line of sight. However, more recent results by other authors indicate
that background subtraction might change these conclusions, so we consider the
effect of background subtraction on our analysis. We show Emission Measure (EM)
Loci plots of three representative pixels: loop apex, upper leg, and lower leg.
Comparisons of the original and background-subtracted intensities show that the
EM Loci are more tightly clustered after background subtraction, but that the
plasma is still not well represented by an isothermal model. Our results taken
together with those of other authors indicate that a variety of temperature
structures may be present within loops.Comment: Accepted for publication in ApJ Letter
Serotonin Transporter Gene Polymorphism Modulates Activity and Connectivity within an Emotional Arousal Network of Healthy Men during an Aversive Visceral Stimulus.
Background and aimsThe 5-hydroxytryptamine transporter gene-linked polymorphic region (5-HTTLPR) has been linked to increased stress responsiveness and negative emotional states. During fearful face recognition individuals with the s allele of 5-HTTLPR show greater amygdala activation. We aimed to test the hypothesis that the 5-HTTLPR polymorphism differentially affects connectivity within brain networks during an aversive visceral stimulus.MethodsTwenty-three healthy male subjects were enrolled. DNA was extracted from the peripheral blood. The genotype of 5-HTTLPR was determined using polymerase chain reaction. Subjects with the s/s genotype (n = 13) were compared to those with the l allele (genotypes l/s, l/l, n = 10). Controlled rectal distension from 0 to 40 mmHg was delivered in random order using a barostat. Radioactive H2[15-O] saline was injected at time of distension followed by positron emission tomography (PET). Changes in regional cerebral blood flow (rCBF) were analyzed using partial least squares (PLS) and structural equation modeling (SEM).ResultsDuring baseline, subjects with s/s genotype demonstrated a significantly increased negative influence of pregenual ACC (pACC) on amygdala activity compared to l-carriers. During inflation, subjects with s/s genotype demonstrated a significantly greater positive influence of hippocampus on amygdala activity compared to l-carriers.ConclusionIn male Japanese subjects, individuals with s/s genotype show alterations in the connectivity of brain regions involved in stress responsiveness and emotion regulation during aversive visceral stimuli compared to those with l carriers
Temperature and Emission-Measure Profiles Along Long-Lived Solar Coronal Loops Observed with TRACE
We report an initial study of temperature and emission measure distributions
along four steady loops observed with the Transition Region and Coronal
Explorer (TRACE) at the limb of the Sun. The temperature diagnostic is the
filter ratio of the extreme-ultraviolet 171-angstrom and 195-angstrom
passbands. The emission measure diagnostic is the count rate in the
171-angstrom passband. We find essentially no temperature variation along the
loops. We compare the observed loop structure with theoretical isothermal and
nonisothermal static loop structure.Comment: 10 pages, 3 postscript figures (LaTeX, uses aaspp4.sty). Accepted by
ApJ Letter
Penilaian Pengunjung Terhadap Layanan Arsip Statis Di Badan Arsip Dan Perpustakaan Provinsi Jawa Tengah
Tujuan penelitian ini adalah mengetahui penilaian pengunjung terhadap petugas layanan di Badan Arsip dan Perpustakaan Provinsi Jawa Tengah, mengetahui penilaian pengunjung terhadap layanan arsip statis arsip di Badan Arsip dan Perpustakaan Provinsi Jawa Tengah, mengetahui penilaian pengunjung terhadap fasilitas layanan yang diberikan oleh Badan Arsip dan Perpustakaan Provinsi Jawa Tengah.Metode yang digunakan dalam penelitian ini adalah metode penelitian deskriptif kuantitatif. Menurut Supardi, “Penelitian deskriptif kuantitatif merupakan penelitian yang menekankan pada pengujian teori – teori melalui pengukuran variabel – variabel penelitian dengan angka kemudian dilakukan analisis. Pengunjung sebagai populasi dan sampel.Hasil penelitian yang diperoleh adalah penilaian pengunjung terhadap petugas layanan dibagi menjadi dua, yaitu sikap dan cara berinteraksi petugas layanan cukup ramah dan kinerja petugas layanan kurang baik. Penilaian pengunjung terhadap layanan arsip statis dibagi menjadi empat, yaitu penilaian pengunjung terhadap prosedur layanan informasi arsip sangat sesuai, biaya retribusi sangat murah, layanan kunjungan kurang sesuai, kelengkapan koleksi arsip cukup sesuai. Penilaian pengunjung terhadap fasilitas layanan dibagi menjadi dua, yaitu penyediaan fasilitas layanan sangat memadai dan sarana dan prasarana cukup maksimal. Simpulan yang didapat bahwa penilaian pengunjung terhadap layanan arsip statis di Badan Arsip dan Perpustakaan Provinsi Jawa Tengah sangat baik dengan presentase 60%
Aplicação foliar de fontes de cálcio na produção de alface sob cultivo protegido.
O objetivo deste trabalho foi avaliar a resposta de plantas de alface à suplementação foliar com carbonato de cálcio (CaCO3+) micronizado
Energy Spectra of Quantum Turbulence: Large-scale Simulation and Modeling
In simulation of quantum turbulence within the Gross-Pitaevskii
equation we demonstrate that the large scale motions have a classical
Kolmogorov-1941 energy spectrum E(k) ~ k^{-5/3}, followed by an energy
accumulation with E(k) ~ const at k about the reciprocal mean intervortex
distance. This behavior was predicted by the L'vov-Nazarenko-Rudenko bottleneck
model of gradual eddy-wave crossover [J. Low Temp. Phys. 153, 140-161 (2008)],
further developed in the paper.Comment: (re)submitted to PRB: 5.5 pages, 4 figure
Comparison of Solar Fine Structure Observed Simultaneously in Ly-{\alpha} and Mg II h
The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in
H I Lyman-{\alpha} during a suborbital rocket flight on September 3, 2015. The
Interface Region Imaging Telescope (IRIS) coordinated with the CLASP
observations and recorded nearly simultaneous and co-spatial observations in
the Mg II h&k lines. The Mg II h and Ly-{\alpha} lines are important
transitions, energetically and diagnostically, in the chromosphere. The
canonical solar atmosphere model predicts that these lines form in close
proximity to each other and so we expect that the line profiles will exhibit
similar variability. In this analysis, we present these coordinated
observations and discuss how the two profiles compare over a region of quiet
sun at viewing angles that approach the limb. In addition to the observations,
we synthesize both line profiles using a 3D radiation-MHD simulation. In the
observations, we find that the peak width and the peak intensities are well
correlated between the lines. For the simulation, we do not find the same
relationship. We have attempted to mitigate the instrumental differences
between IRIS and CLASP and to reproduce the instrumental factors in the
synthetic profiles. The model indicates that formation heights of the lines
differ in a somewhat regular fashion related to magnetic geometry. This
variation explains to some degree the lack of correlation, observed and
synthesized, between Mg II and Ly-{\alpha}. Our analysis will aid in the
definition of future observatories that aim to link dynamics in the
chromosphere and transition region.Comment: Accepted by Ap
Causes of breakage and disruption in a homogeniser
Many authors have written in the past regarding the exact causes of breakage and disruption in a high pressure homogeniser, but there has been little agreement. This paper investigates some of the most likely causes of the rupture of the walls of unicellular organisms and offers suggestions obtained from various papers and work carried out
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