12,254 research outputs found
First High-resolution Spectroscopic Observations of an Erupting Prominence Within a Coronal Mass Ejection by the Interface Region Imaging Spectrograph (IRIS)
Spectroscopic observations of prominence eruptions associated with coronal
mass ejections (CMEs), although relatively rare, can provide valuable plasma
and 3D geometry diagnostics. We report the first observations by the Interface
Region Imaging Spectrograph (IRIS) mission of a spectacular fast CME/prominence
eruption associated with an equivalent X1.6 flare on 2014 May 9. The maximum
plane-of-sky and Doppler velocities of the eruption are 1200 and 460 km/s,
respectively. There are two eruption components separated by ~200 km/s in
Doppler velocity: a primary, bright component and a secondary, faint component,
suggesting a hollow, rather than solid, cone-shaped distribution of material.
The eruption involves a left-handed helical structure undergoing
counter-clockwise (viewed top-down) unwinding motion. There is a temporal
evolution from upward eruption to downward fallback with less-than-free-fall
speeds and decreasing nonthermal line widths. We find a wide range of Mg II k/h
line intensity ratios (less than ~2 expected for optically-thin thermal
emission): the lowest ever-reported median value of 1.17 found in the fallback
material and a comparably high value of 1.63 in nearby coronal rain and
intermediate values of 1.53 and 1.41 in the two eruption components. The
fallback material exhibits a strong () linear correlation between
the k/h ratio and the Doppler velocity as well as the line intensity. We
demonstrate that Doppler dimming of scattered chromospheric emission by the
erupted material can potentially explain such characteristics.Comment: 12 pages, 6 figures, accepted by ApJ (Feb 15, 2015
Quasiequilibrium sequences of black-hole--neutron-star binaries in general relativity
We construct quasiequilibrium sequences of black hole-neutron star binaries
for arbitrary mass ratios by solving the constraint equations of general
relativity in the conformal thin-sandwich decomposition. We model the neutron
star as a stationary polytrope satisfying the relativistic equations of
hydrodynamics, and account for the black hole by imposing equilibrium boundary
conditions on the surface of an excised sphere (the apparent horizon). In this
paper we focus on irrotational configurations, meaning that both the neutron
star and the black hole are approximately nonspinning in an inertial frame. We
present results for a binary with polytropic index n=1, mass ratio
M_{irr}^{BH}/M_{B}^{NS}=5 and neutron star compaction
M_{ADM,0}^{NS}/R_0=0.0879, where M_{irr}^{BH} is the irreducible mass of the
black hole, M_{B}^{NS} the neutron star baryon rest-mass, and M_{ADM,0}^{NS}
and R_0 the neutron star Arnowitt-Deser-Misner mass and areal radius in
isolation, respectively. Our models represent valid solutions to Einstein's
constraint equations and may therefore be employed as initial data for
dynamical simulations of black hole-neutron star binaries.Comment: 5 pages, 1 figure, revtex4, published in Phys.Rev.
Homotransplantation of multiple visceral organs
It was technically possible to perform simultaneous homotransplantation of multiple visceral organs including the liver, spleen, pancreas, omentum and the entire gastrointestinal tract. Arterialization of the cooled graft was accomplished through the donor aorta which was removed with the graft and attached to that of the recipient dog. Gastrointestinal hemorrhage after surgery accounted for a high operative mortality and was thought to be due to denervation of the graft. The five dogs which survived the immediate trauma of surgery lived for five and a half to nine days. After the second day, these animals were physically active and able to resume oral alimentation. In three dogs, there was metabolic evidence of rejection of the liver. In two others, jaundice did not develop. These observations were compared with chemical, hematologic and pathologic data obtained in previous experiments involving homotransplantation of the liver alone. In some cases, there was less evidence of host versus graft rejection after the multiple organ transplants. Other data in the present study suggested the possibility that a significant graft versus host reaction may have been an important contributory cause of death. © 1962
Development of the Swiss Database for dosing medicinal products in pediatrics
In daily paediatrics, drugs are commonly used off-label, as they are not approved for children. Approval is lacking because the required clinical studies were limited to adults in the past. Without clinical studies, evidence-based recommendations for drug use in children are limited. Information on off-label drug dosing in children can be found in different handbooks, databases and scientific publications but the dosing recommendations can differ considerably. To improve safety and efficacy of drugs prescribed to children and to assist the prescribers, stakeholders in Swiss paediatrics started a pilot project, supported by the Federal Office of Public Health, with the aim to create a database, providing healthcare professionals with so called “harmonised” dosage recommendations based on the latest available scientific evidence and best clinical practice. A standardised process for dosage harmonisation between paediatric experts was defined, guided and documented in an electronic tool, developed for this purpose. As proof of principle, a total of 102 dosage recommendations for 30 different drugs have been nationally harmonised in the pilot phase considering the current scientific literature and the approval of the most experienced national experts in the field.
Conclusion: This approach paved the way for unified national dosage recommendations for children. Reaching the project’s milestones fulfilled the prerequisites for funding and starting regular operation of SwissPedDose in 2018. Since then, the database was extended with recommendations for 100 additional drugs
Proton Stability in Six Dimensions
We show that Lorentz and gauge invariance explain the long proton lifetime
within the standard model in six dimensions. The baryon-number violating
operators have mass dimension 15 or higher. Upon TeV-scale compactification of
the two universal extra dimensions on a square orbifold, a discrete
subgroup of the 6-dimensional Lorentz group continues to forbid dangerous
operators.Comment: PRL accepted versio
Phase Referencing in Optical Interferometry
One of the aims of next generation optical interferometric instrumentation is
to be able to make use of information contained in the visibility phase to
construct high dynamic range images. Radio and optical interferometry are at
the two extremes of phase corruption by the atmosphere. While in radio it is
possible to obtain calibrated phases for the science objects, in the optical
this is currently not possible. Instead, optical interferometry has relied on
closure phase techniques to produce images. Such techniques allow only to
achieve modest dynamic ranges. However, with high contrast objects, for faint
targets or when structure detail is needed, phase referencing techniques as
used in radio interferometry, should theoretically achieve higher dynamic
ranges for the same number of telescopes. Our approach is not to provide
evidence either for or against the hypothesis that phase referenced imaging
gives better dynamic range than closure phase imaging. Instead we wish to
explore the potential of this technique for future optical interferometry and
also because image reconstruction in the optical using phase referencing
techniques has only been performed with limited success. We have generated
simulated, noisy, complex visibility data, analogous to the signal produced in
radio interferometers, using the VLTI as a template. We proceeded with image
reconstruction using the radio image reconstruction algorithms contained in
AIPS IMAGR (CLEAN algorithm). Our results show that image reconstruction is
successful in most of our science cases, yielding images with a 4
milliarcsecond resolution in K band. (abridged)Comment: 11 pages, 36 figure
Ursinus College Alumni Journal, Spring 1945
In memoriam • President\u27s page • Commencement • Spring term opens • Forum speakers • Dramatics • Christmas festivities • Sports revue • Visitors date • Dances • Debating • Y.M. and Y.W. events • Operetta • Messages to the alumni • College presidents sponsor legislation • Ursinus is family tradition • News about ourselves • Necrology • Our war correspondents • Program for veterans • Ursinus honor roll • Men and women in the service • Alumni Association nomineeshttps://digitalcommons.ursinus.edu/alumnijournal/1024/thumbnail.jp
Initial Helioseismic Observations by Hinode/SOT
Results from initial helioseismic observations by Solar Optical Telescope
onboard Hinode are reported. It has been demonstrated that intensity
oscillation data from Broadband Filter Imager can be used for various
helioseismic analyses. The k-omega power spectra, as well as corresponding
time-distance cross-correlation function that promises high-resolution
time-distance analysis below 6-Mm travelling distance, were obtained for G-band
and CaII-H data. Subsurface supergranular patterns have been observed from our
first time-distance analysis. The results show that the solar oscillation
spectrum is extended to much higher frequencies and wavenumbers, and the
time-distance diagram is extended to much shorter travel distances and times
than they were observed before, thus revealing great potential for
high-resolution helioseismic observations from Hinode.Comment: 6 pages, accepted for publication in PAS
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