10,112 research outputs found
Reconciliation of the Surface Brightness Fluctuations and Type Ia Supernovae Distance Scales
We present Hubble Space Telescope measurements of surface brightness
fluctuations (SBF) distances to early-type galaxies that have hosted Type Ia
supernovae (SNIa). The agreement in the relative SBF and SNIa multicolor light
curve shape and delta-m_15 distances is excellent. There is no systematic scale
error with distance, and previous work has shown that SBF and SNIa give
consistent ties to the Hubble flow. However, we confirm a systematic offset of
about 0.25 mag in the distance zero points of the two methods, and we trace
this offset to their respective Cepheid calibrations. SBF has in the past been
calibrated with Cepheid distances from the H_0 Key Project team, while SNIa
have been calibrated with Cepheid distances from the team composed of Sandage,
Saha, and collaborators. When the two methods are calibrated in a consistent
way, their distances are in superb agreement. Until the conflict over the
``long'' and ``short'' extragalactic Cepheid distances among many galaxies is
resolved, we cannot definitively constrain the Hubble constant to better than
about 10%, even leaving aside the additional uncertainty in the distance to the
Large Magellanic Cloud, common to both Cepheid scales. However, recent
theoretical SBF predictions from stellar population models favor the Key
Project Cepheid scale, while the theoretical SNIa calibration lies between the
long and short scales. In addition, while the current SBF distance to M31/M32
is in good agreement with the RR Lyrae and red giant branch distances,
calibrating SBF with the longer Cepheid scale would introduce a 0.3 mag offset
with respect to the RR Lyrae scale.Comment: 13 pages, 3 PostScript figures, LaTeX with AASTeX 5.02 and natbib.sty
v7.0 (included). Accepted for publication in The Astrophysical Journa
A Preliminary Indication of Evolution of Type Ia Supernovae from their Risetimes
We have compared the risetime for samples of nearby and high-redshift type Ia
supernovae (SNe Ia).
The fiducial risetime of the nearby SNe Ia is 2.5+/-0.4 days longer than the
proemial risetime determined by Goldhaber (1998a,b) for high-redshift SNe
Ia from the Supernova Cosmology Project.
The statistical likelihood that the two samples have different fiducial
risetimes is high (5.8 sigma) and indicates possible evolution between the
samples of SNe Ia. We consider the likely effects of several sources of
systematic error, but none of these resolves the difference in the risetimes.
Currently, we cannot directly determine the impact of the apparent evolution
on previous determinations of cosmological parameters.Comment: Accepted by the Astronomical Journal, 11 pages, 5 figure
Early increase in blood pressure and diastolic left ventricular malfunction in patients with glomerulonephritis
Early increase in blood pressure and diastolic left ventricular malfunction in patients with glomerulonephritis. In patients with diabetic nephropathy blood pressure increases progressively before the conventional threshold of normal blood pressure (140/90mm Hg) is transgressed. In patients with glomerulonephritis, no information on this point is available. To clarify this issue we sequentially examined 20 untreated patients with biopsy-proven primary chronic glomerulonephritis (GN) who had casual blood pressure below 140/90mm Hg and normal GFR by inulin clearance. Patients were compared with normotensive healthy controls who were matched for BMI, gender and age. We measured ambulatory 24-hour blood pressure (SpaceLab system), echocardiography (ASE criteria, Acuson 128 XP 10), CIn and CPAH, urinary Na excretion, PRA and insulin concentration. In patients with GN, the median 24 hour (P < 0.0005), daytime (P < 0.001) and nocturnal sleeping time (P < 0.0001) MAP values were significantly higher than in matched controls (daytime, mean 97mm Hg, 85 to 106 GN vs. 89 controls range 82 to 102; nocturnal sleeping time, mean 80.3mm Hg, 71 to 89.5 GN vs. 73 controls, range 63 to 84). Echocardiographic examination showed significantly greater posterior wall thickness (P < 0.01) and ventricular septal thickness (P < 0.003). In addition the early diastolic to late diastolic (E/A) ratio of mitral valve peak inflow velocity was significantly (P < 0.0008) lower in patients. The data point to left ventricular wall thickening accompanied by LV diastolic malfunction. The study documents elevated ambulatory blood pressure in patients with primary chronic glomerulonephritis despite normal body weight and normal GFR. This is associated with evidence of target organ damage in the heart. The findings suggest that in patients with glomerulonephritis blood pressure increases initially within the normotensive range. This observation in conjunction with evidence of early target organ changes provides an argument for early antihypertensive intervention, but controlled trials to test efficacy and safety of this proposal are necessary
BVRI Light Curves for 22 Type Ia Supernovae
We present 1210 Johnson/Cousins B,V,R, and I photometric observations of 22
recent type Ia supernovae (SNe Ia): SN 1993ac, SN 1993ae, SN 1994M, SN 1994S,
SN 1994T, SN 1994Q, SN 1994ae, SN 1995D, SN 1995E, SN 1995al, SN 1995ac, SN
1995ak, SN 1995bd, SN 1996C, SN 1996X, SN 1996Z, SN 1996ab, SN 1996ai, SN
1996bk, SN 1996bl, SN 1996bo, and SN 1996bv. Most of the photometry was
obtained at the Fred Lawrence Whipple Observatory (FLWO) of the
Harvard-Smithsonian Center for Astrophysics in a cooperative observing plan
aimed at improving the data base for SN Ia. The redshifts of the sample range
from =1200 to 37000 km s with a mean of =7000 km s.Comment: Accepted to the Astronomical Journal, 41 pages, 8 figure
Singular value decomposition and matrix reorderings in quantum information theory
We review Schmidt and Kraus decompositions in the form of singular value
decomposition using operations of reshaping, vectorization and reshuffling. We
use the introduced notation to analyse the correspondence between quantum
states and operations with the help of Jamiolkowski isomorphism. The presented
matrix reorderings allow us to obtain simple formulae for the composition of
quantum channels and partial operations used in quantum information theory. To
provide examples of the discussed operations we utilize a package for the
Mathematica computing system implementing basic functions used in the
calculations related to quantum information theory.Comment: 11 pages, no figures, see
http://zksi.iitis.pl/wiki/projects:mathematica-qi for related softwar
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