4,740 research outputs found
Asymptotic Spectrum of Kerr Black Holes in the Small Angular Momentum Limit
We study analytically the highly damped quasinormal modes of Kerr black holes
in the small angular momentum limit. To check the previous analytic
calculations in the literature, which use a combination of radial and tortoise
coordinates, we reproduce all the results using the radial coordinate only.
According to the earlier calculations, the real part of the highly damped
quasinormal mode frequency of Kerr black holes approaches zero in the limit
where the angular momentum goes to zero. This result is not consistent with the
Schwarzschild limit where the real part of the highly damped quasinormal mode
frequency is equal to c^3 ln(3)/(8 pi G M). In this paper, our calculations
suggest that the highly damped quasinormal modes of Kerr black holes in the
zero angular momentum limit make a continuous transition from the Kerr value to
the Schwarzschild value. We explore the nature of this transition using a
combination of analytical and numerical techniques. Finally, we calculate the
highly damped quasinormal modes of the extremal case in which the topology of
Stokes/anti-Stokes lines takes a different form.Comment: 13 pages, 6 figure
Isolated familial pheochromocytoma as a variant of von Hippel-Lindau disease.
Inherited pheochromocytomas are often part of familial syndromes, especially multiple endocrine neoplasia type 2 (MEN 2), retinal cerebellar hemangioblastomatosis [von Hippel-Lindau (vHL) disease] or neurofibromatosis type 1. It is not clear whether isolated familial pheochromocytoma exists as a separate clinical entity. In a family with pheochromocytomas in three generations and with at least seven affected members, we investigated by clinical and genetic analyses the presence or absence of associated conditions. The clinical investigations included ophthalmological and radiological studies for von Hippel-Lindau disease (magnetic resonance imaging of the brain, computed tomography of the abdomen, and direct ophthalmoscopy after mydriasis) and annual calcitonin stimulation tests for C cell disease in five members who agreed to regular follow-up. Besides the pheochromocytomas (so far, these have been multiple in five of seven individuals) no definite second associated condition was found. Genetic analysis did not identify any MEN 2-specific RET protooncogene point mutations (which are present in 97% of MEN 2a families). However, despite the complete absence of other clinical manifestations of the vHL disease (besides pheochromocytomas), a previously undescribed germline missense mutation in the vHL tumor suppressor gene was found (C775G transversion with a predicted substitution of a leucine by a valine at codon 259 in the putative vHL protein). We conclude that in this family the sole occurrence of pheochromocytoma is a variant of vHL disease
Enseñanzas mínimas de educación infantil : Real Decreto 1630-2006, de 29 de diciembre, por el que se establecen las enseñanzas mínimas del segundo ciclo de educación infantil
Se presenta el Real Decreto 1630-2006, de 29 de diciembre que establece las enseñanzas mínimas a impartirse en el segundo ciclo de educación infantil. Se indican los objetivos, contenidos y criterios de evaluación de cada una de las áreas que integran el segundo ciclo de educación infantil.MadridBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín 5 -3 Planta; 28014 Madrid; Tel. +34917748000; [email protected]
Gaseous Electronics
Contains reports on three research projects.Joint Services Electronics Program (Contract DAAB07-71-C-0300
Identity priming consistently affects perceptual fluency but only affects metamemory when primes are obvious.
Perceptual fluency manipulations influence metamemory judgments, with more fluently perceived information judged as more memorable. However, it is not always clear whether this influence is driven by actual experienced processing fluency or by beliefs about memory. The current study used an identity-priming paradigm--in which words are preceded by either matched (identical) or mismatched primes--to examine the 2 influences. Participants named and made judgments of learning (JOLs) for critical words and then completed a memory test. In Experiment 1, we briefly presented the primes and found a priming effect on naming latencies but not on JOLs. In Experiment 2, we presented the primes for longer durations and, again, found an effect on naming in addition to an effect on JOLs. A mediation analysis revealed that naming latencies did not account for the prime--JOL relationship. This pattern of results demonstrated a manipulation of perceptual fluency that influenced JOLs only whe
High-Velocity Features of Calcium and Silicon in the Spectra of Type Ia Supernovae
"High-velocity features" (HVFs) are spectral features in Type Ia supernovae
(SNe Ia) that have minima indicating significantly higher (by greater than
about 6000 km/s) velocities than typical "photospheric-velocity features"
(PVFs). The PVFs are absorption features with minima indicating typical
photospheric (i.e., bulk ejecta) velocities (usually ~9000-15,000 km/s near
B-band maximum brightness). In this work we undertake the most in-depth study
of HVFs ever performed. The dataset used herein consists of 445 low-resolution
optical and near-infrared (NIR) spectra (at epochs up to 5 d past maximum
brightness) of 210 low-redshift SNe Ia that follow the "Phillips relation." A
series of Gaussian functions is fit to the data in order to characterise
possible HVFs of Ca II H&K, Si II {\lambda}6355, and the Ca II NIR triplet. The
temporal evolution of the velocities and strengths of the PVFs and HVFs of
these three spectral features is investigated, as are possible correlations
with other SN Ia observables. We find that while HVFs of Ca II are regularly
observed (except in underluminous SNe Ia, where they are never found), HVFs of
Si II {\lambda}6355 are significantly rarer, and they tend to exist at the
earliest epochs and mostly in objects with large photospheric velocities. It is
also shown that stronger HVFs of Si II {\lambda}6355 are found in objects that
lack C II absorption at early times and that have red ultraviolet/optical
colours near maximum brightness. These results lead to a self-consistent
connection between the presence and strength of HVFs of Si II {\lambda}6355 and
many other mutually correlated SN~Ia observables, including photospheric
velocity.Comment: 48 pages (22 of which are tables), 15 figures, 5 tables, re-submitted
to MNRAS (after first referee report
The Impact of Spatial Heterogeneity in Land Use Practices and Aquifer Characteristics on Groundwater Conservation Policy Cost
Estimation of agricultural policy cost for a given level of groundwater conservation requires the establishment of an accurate baseline condition. This is especially critical when the benefits and cost of any conservation program are generally estimated relative to the status quo policy or baseline situation. An inaccurate baseline estimate will lead to poor estimates of potential water conservation savings and agricultural policy cost. Over a 60-year planning horizon per acre net present value is as much as 29.8% higher for a study area when aquifer characteristics are assumed to be homogenous and set to their average area value than when the heterogeneity in aquifer characteristics is explicitly modeled.Aquifer Modeling, Economics, Resource /Energy Economics and Policy,
Wolf 1130: A Nearby Triple System Containing a Cool, Ultramassive White Dwarf
Following the discovery of the T8 subdwarf WISEJ200520.38+542433.9 (Wolf
1130C), with common proper motion to a binary (Wolf 1130AB) consisting of an M
subdwarf and a white dwarf, we set out to learn more about the old binary in
the system. We find that the A and B components of Wolf 1130 are tidally
locked, which is revealed by the coherence of more than a year of V band
photometry phase folded to the derived orbital period of 0.4967 days. Forty new
high-resolution, near-infrared spectra obtained with the Immersion Grating
Infrared Spectrometer (IGRINS) provide radial velocities and a projected
rotational velocity (v sin i) of 14.7 +/- 0.7 km/s for the M subdwarf. In
tandem with a Gaia parallax-derived radius and verified tidal-locking, we
calculate an inclination of i=29 +/- 2 degrees. From the single-lined orbital
solution and the inclination we derive an absolute mass for the unseen primary
(1.24+0.19-0.15 Msun). Its non-detection between 0.2 and 2.5 microns implies
that it is an old (>3.7 Gyr) and cool (Teff<7000K) ONe white dwarf. This is the
first ultramassive white dwarf within 25pc. The evolution of Wolf 1130AB into a
cataclysmic variable is inevitable, making it a potential Type Ia supernova
progenitor. The formation of a triple system with a primary mass >100 times the
tertiary mass and the survival of the system through the common-envelope phase,
where ~80% of the system mass was lost, is remarkable. Our analysis of Wolf
1130 allows us to infer its formation and evolutionary history, which has
unique implications for understanding low-mass star and brown dwarf formation
around intermediate mass stars.Comment: 37 pages, 9 Figures, 5 Table
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