2,759 research outputs found
Electron, ion and neutral temperatures at the magnetic equator
Electron density and electron, ion, and neutral temperature profiles at magnetic equato
Interactive Simplifier Tracing and Debugging in Isabelle
The Isabelle proof assistant comes equipped with a very powerful tactic for
term simplification. While tremendously useful, the results of simplifying a
term do not always match the user's expectation: sometimes, the resulting term
is not in the form the user expected, or the simplifier fails to apply a rule.
We describe a new, interactive tracing facility which offers insight into the
hierarchical structure of the simplification with user-defined filtering,
memoization and search. The new simplifier trace is integrated into the
Isabelle/jEdit Prover IDE.Comment: Conferences on Intelligent Computer Mathematics, 201
Late Holocene Tsunami Deposits at Salt Creek, Washington, USA
We interpret two thin sand layers in the estuarine marsh at Salt Creek, on the southern shore of the Strait of Juan de Fuca, as the products of tsunamis propagated by earthquakes at the Cascadia subduction zone. The sand layers extend for about 60 m along the left bank of the creek about 800 m from the mouth, and can be traced to the base of a nearby upland area. One layer is exposed in the creek bank about 400 m further upstream, but they are only patchily distributed in the rest of the central area of the marsh. Both layers contain brackish-marine epipsammic diatoms. The lower sand layer marks a sharp contact between intertidal peaty mud and overlying mud, perhaps reflecting modest coseismic subsidence in association with tsunami deposition, but little or no change in the bracketing sediment occurs in association with the upper sand layer. The ages of the sand layers are not closely constrained, but were most likely deposited by tsunamis generated by great earthquakes at the Cascadia subduction zone about 1650 and 1300 years ago. The Cascadia great earthquake of AD1700 may have induced slight subsidence in the marsh, but no tsunami deposit was detected at the inferred contact. The absence of deposits from the marsh immediately inland of the 4 m-high barrier beach indicates that the largest tsunamis in the late Holocene at this site have not overtopped the barrier, which suggests that these tsunamis were likely only 2-3 m high
Evidence of Twisting and Mixed-polarity Solar Photospheric Magnetic Field in Large Penumbral Jets: IRIS and Hinode Observations
A recent study using {\it Hinode} (SOT/FG) data of a sunspot revealed some
unusually large penumbral jets that often repeatedly occurred at the same
locations in the penumbra, namely at the tail of a penumbral filament or where
the tails of multiple penumbral filaments converged. These locations had
obvious photospheric mixed-polarity magnetic flux in \NaI\ 5896 Stokes-V images
obtained with SOT/FG. Several other recent investigations have found that
extreme ultraviolet (EUV)/X-ray coronal jets in quiet Sun regions (QRs),
coronal holes (CHs) and near active regions (ARs) have obvious mixed-polarity
fluxes at their base, and that magnetic flux cancellation prepares and triggers
a minifilament flux-rope eruption that drives the jet. Typical QR, CH, and AR
coronal jets are up to a hundred times bigger than large penumbral jets, and in
EUV/X-ray images show clear twisting motion in their spires. Here, using IRIS
\MgII\ k 2796 \AA\ SJ images and spectra in the penumbrae of two sunspots we
characterize large penumbral jets. We find redshift and blueshift next to each
other across several large penumbral jets, and interpret these as untwisting of
the magnetic field in the jet spire. Using Hinode/SOT (FG and SP) data, we also
find mixed-polarity magnetic flux at the base of these jets. Because large
penumbral jets have mixed-polarity field at their base and have twisting motion
in their spires, they might be driven the same way as QR, CH and AR coronal
jets.Comment: 18 pages, 11 figures; to appear in Ap
Simultaneous Observations of the Chromosphere with TRACE and SUMER
Using mainly the 1600 angstrom continuum channel, and also the 1216 angstrom
Lyman-alpha channel (which includes some UV continuum and C IV emission),
aboard the TRACE satellite, we observed the complete lifetime of a transient,
bright chromospheric loop. Simultaneous observations with the SUMER instrument
aboard the SOHO spacecraft revealed interesting material velocities through the
Doppler effect existing above the chromospheric loop imaged with TRACE,
possibly corresponding to extended non-visible loops, or the base of an X-ray
jet.Comment: 14 pages, 10 figures, accepted by Solar Physic
Profiting from Protecting Small Business Borrowers: Take That to the Bank!
While small businesses represent a significant portion of the economy, there is mounting evidence that the playing field is not level for these firms in access to capital. Based on 10 years of matched-paired mystery shopping tests in banks to investigate bank lending practices and customer experience, the results demonstrate that in almost every instance, minorities were treated more poorly than their White counterparts. However, the authors acknowledge the controversy surrounding this issue, as some question the need for government action to push banks in this direction. Before offering evidence of the impact race can have on the treatment of small business owners who apply for loans, they present two frameworks which support the adoption of race-based criteria in evaluating bank performance, namely, Corporate Social Responsibility and Corporate Social Innovation. They then provide a summary of the results of mystery shopping studies they have conducted, concluding that banks are leaving profits on the table through their discriminatory practices
Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets
By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T ~10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets
Toward a better understanding of the comparatively high prostate cancer incidence rates in Utah
BACKGROUND: This study assesses whether comparatively high prostate cancer incidence rates among white men in Utah represent higher rates among members of the Church of Jesus Christ of Latter-day Saints (LDS or Mormons), who comprise about 70% of the state's male population, and considers the potential influence screening has on these rates. METHODS: Analyses are based on 14,693 histologically confirmed invasive prostate cancer cases among men aged 50 years and older identified through the Utah Cancer Registry between 1985 and 1999. Cancer records were linked to LDS Church membership records to determine LDS status. Poisson regression was used to derive rate ratios of LDS to nonLDS prostate cancer incidence, adjusted for age, disease stage, calendar time, and incidental detection. RESULTS: LDS men had a 31% (95% confidence interval, 26% – 36%) higher incidence rate of prostate cancer than nonLDS men during the study period. Rates were consistently higher among LDS men over time (118% in 1985–88, 20% in 1989–92, 15% in 1993–1996, and 13% in 1997–99); age (13% in ages 50–59, 48% in ages 60–69, 28% in ages 70–79, and 16% in ages 80 and older); and stage (36% in local/regional and 17% in unstaged). An age- and stage-shift was observed for both LDS and nonLDS men, although more pronounced among LDS men. CONCLUSIONS: Comparatively high prostate cancer incidence rates among LDS men in Utah are explained, at least in part, by more aggressive screening among these men
Sunspot rotation, filament, and flare: The event on 2000 February 10
We find that a sunspot with positive polarity had an obvious
counter-clockwise rotation and resulted in the formation and eruption of an
inverse S-shaped filament in NOAA active region (AR) 08858 from 2000 February 9
to 10. The sunspot had two umbrae which rotated around each other by 195
degrees within about twenty-four hours. The average rotation rate was nearly 8
degrees per hour. The fastest rotation in the photosphere took place during
14:00UT to 22:01UT on February 9, with the rotation rate of nearly 16 degrees
per hour. The fastest rotation in the chromosphere and the corona took place
during 15:28UT to 19:00UT on February 9, with the rotation rate of nearly 20
degrees per hour. Interestingly, the rapid increase of the positive magnetic
flux just occurred during the fastest rotation of the rotating sunspot, the
bright loop-shaped structure and the filament. During the sunspot rotation, the
inverse S-shaped filament gradually formed in the EUV filament channel. The
filament experienced two eruptions. In the first eruption, the filament rose
quickly and then the filament loops carrying the cool and the hot material were
seen to spiral into the sunspot counterclockwise. About ten minutes later, the
filament became active and finally erupted. The filament eruption was
accompanied with a C-class flare and a halo coronal mass ejection (CME). These
results provide evidence that sunspot rotation plays an important role in the
formation and eruption of the sigmoidal active-region filament.Comment: 20 pages, 9 figures, Accepted for publication in Ap
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