245 research outputs found
Udsigt over Udførselen af Korn-, Fede- og andre Varer fra Kongeriget Danmark og Hertugdømmerne Slesvig og Holsteen i Aarene 1838 og 1839.
Udsigt over Udførselen af Korn-, Fede- og andre Varer fra Kongeriget Danmark og Hertugdømmerne Slesvig og Holsteen i Aarene 1838 og 1839
The Initial Mass Function in the Nearest Strong Lenses from SNELLS: Assessing the Consistency of Lensing, Dynamical, and Spectroscopic Constraints
We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferred to have a stellar initial mass function (IMF) consistent with that of the Milky Way, not the bottom-heavy IMF that has been reported as typical for high-σ ETGs based on lensing, dynamical, and stellar population synthesis techniques. We use these unique systems to test the consistency of IMF estimates derived from different methods. We first estimate the stellar M */L using lensing and stellar dynamics. We then fit high-quality optical spectra of the lenses using an updated version of the stellar population synthesis models developed by Conroy & van Dokkum. When examined individually, we find good agreement among these methods for one galaxy. The other two galaxies show 2–3σ tension with lensing estimates, depending on the dark matter contribution, when considering IMFs that extend to 0.08 M ⊙. Allowing a variable low-mass cutoff or a nonparametric form of the IMF reduces the tension among the IMF estimates to <2σ. There is moderate evidence for a reduced number of low-mass stars in the SNELLS spectra, but no such evidence in a composite spectrum of matched-σ ETGs drawn from the SDSS. Such variation in the form of the IMF at low stellar masses (m lesssim 0.3 M ⊙), if present, could reconcile lensing/dynamical and spectroscopic IMF estimates for the SNELLS lenses and account for their lighter M */L relative to the mean matched-σ ETG. We provide the spectra used in this study to facilitate future comparisons
A New Conceptualization and Approach to Learning and Teaching Motivational Interviewing
Type: Idea Pape
Suppression of hidden order in URu2Si2 under pressure and restoration in magnetic field
We describe here recent inelastic neutron scattering experiments on the heavy
fermion compound URu2Si2 realized in order to clarify the nature of the hidden
order (HO) phase which occurs below T_0 = 17.5 K at ambient pressure. The
choice was to measure at a given pressure P where the system will go, by
lowering the temperature, successively from paramagnetic (PM) to HO and then to
antiferromagnetic phase (AF). Furthermore, in order to verify the selection of
the pressure, a macroscopic detection of the phase transitions was also
achieved in situ via its thermal expansion response detected by a strain gauge
glued on the crystal. Just above P_x = 0.5 GPa, where the ground state switches
from HO to AF, the Q_0 = (1, 0, 0) excitation disappears while the excitation
at the incommensurate wavevector Q_1 = (1.4, 0, 0) remains. Thus, the Q_0 = (1,
0, 0) excitation is intrinsic only in the HO phase. This result is reinforced
by studies where now pressure and magnetic field can be used as tuning
variable. Above P_x, the AF phase at low temperature is destroyed by a magnetic
field larger than H_AF (collapse of the AF Q_0 = (1, 0, 0) Bragg reflection).
The field reentrance of the HO phase is demonstrated by the reappearance of its
characteristic Q_0 = (1, 0, 0) excitation. The recovery of a PM phase will only
be achieved far above H_AF at H_M approx 35 T. To determine the P-H-T phase
diagram of URu2Si2, macroscopic measurements of the thermal expansion were
realized with a strain gauge. The reentrant magnetic field increases strongly
with pressure. Finally, to investigate the interplay between superconductivity
(SC) and spin dynamics, new inelastic neutron scattering experiments are
reported down to 0.4 K, far below the superconducting critical temperature T_SC
approx 1.3 K as measured on our crystal by diamagnetic shielding.Comment: 5 pages, 7 figures, ICN 2009 conference proceeding
Mars Science Laboratory Workstation Test Set
The Mars Science Laboratory developed the Workstation TestSet (WSTS) is a computer program that enables flight software development on virtual MSL avionics. The WSTS is the non-real-time flight avionics simulator that is designed to be completely software-based and run on a workstation class Linux PC
Still at Odds with Conventional Galaxy Evolution: The Star Formation History of Ultra-Diffuse Galaxy Dragonfly 44
We study the star formation history (SFH) of the ultra-diffuse galaxy (UDG)
Dragonfly 44 (DF44) based on the simultaneous fit to near-ultraviolet to
near-infrared photometry and high signal-to-noise optical spectroscopy. In
fitting the observations we adopt an advanced physical model with a flexible
SFH, and we discuss the results in the context of the degeneracies between
stellar population parameters. Through reconstructing the mass-assembly history
with a prior for extended star formation (akin to methods in the literature) we
find that DF44 formed 90 per cent of its stellar mass by ( Gyr ago). In comparison, using a prior that prefers concentrated star
formation (as informed by previous studies of DF44's stellar populations)
suggests that DF44 formed as early as ( Gyr ago).
Regardless of whether DF44 is old or very old, the SFHs imply early star
formation and rapid quenching. This result, together with DF44's large size and
evidence that it is on its first infall into the Coma cluster, challenges UDG
formation scenarios from simulations that treat all UDGs as contiguous with the
canonical dwarf population. While our results cannot confirm any particular
formation scenario, we can conclude from this that DF44 experienced a rare
quenching event.Comment: 25 pages, 15 figures. Accepted for publication in MNRA
Why the hidden order in URu2Si2 is still hidden - one simple answer
For more than two decades, the nonmagnetic anomaly observed around 17.5 K in
URu2Si2, has been investigated intensively. However, any kind of fingerprint
for the lattice anomaly has not been observed. Therefore, the order has been
called "the hidden order". One simple answer to why the hidden order is still
hidden is presented from the space group analysis. The second order phase
transition from I4/mmm (No. 139) to P4_2/mnm (No. 136) does not need any kind
of lattice distortion in this system, and allows the NQR frequency at Ru-site
unchanged. It is compatible with O_{xy}-type anti-ferro quadrupole ordering
with Q=(0, 0, 1). The characteristics of the hidden order are discussed based
on the local 5f^2 electron picture.Comment: Accepted for publication in J. Phys. Soc. Jpn., 4 pages, 2 figure
Field Reentrance of the Hidden Order State of URu2Si2 under Pressure
Combination of neutron scattering and thermal expansion measurements under
pressure shows that the so-called hidden order phase of URu2Si2 reenters in
magnetic field when antiferromagnetism (AF) collapses at H_AF (T). Macroscopic
pressure studies of the HO-AF boundaries were realized at different pressures
via thermal expansion measurements under magnetic field using a strain gauge.
Microscopic proof at a given pressure is the reappearance of the resonance at
Q_0=(1,0,0) under field which is correlated with the collapse of the AF Bragg
reflections at Q_0.Comment: 5 pages, 6 figures, accepted for publication in J. Phys. Soc. Jp
A nonlinear method of removing harmonic noise in geophysical data
A nonlinear, adaptive method to remove the harmonic noise that commonly resides in geophysical data is proposed in this study. This filtering method is based on the ensemble empirical mode decomposition algorithm in conjunction with the logarithmic transform. We present a synthetic model study to investigate the capability of signal reconstruction from the decomposed data, and compare the results with those derived from other 2-D adaptive filters. Applications to the real seismic data acquired by using an ocean bottom seismograph and to a shot gather of the ground penetrating radar demonstrate the robustness of this method. Our work proposes a concept that instead of Fourier-based approaches, the harmonic noise removal in geophysical data can be achieved effectively by using an alternative nonlinear adaptive data analysis method, which has been applied extensively in other scientific studies
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