1,818 research outputs found
Thyroxine-binding globulin: investigation of microheterogeneity
Preparations of T4-binding globulin (TBG) from human serum was performed using only two affinity chromatography steps. Purity of the protein was demonstrated by a single band in overloaded disc and sodium dodecyl sulfate electrophoresis, equimolar binding to T4, and linearity in sedimentation velocity run. The molecular weight was calculated to be 60,000 +/- 3,000 daltons (n = 3), the sedimentation coefficient was 3.95S, and the Stokes' radius was 37 A. The amino acid composition was found to be in good agreement with the calculations of other authors. By isoelectric focussing (IEF), pure TBG showed four main bands at pH 4.25, 4.35, 4.45, and 4.55 together with several fainter bands. The N- acetylneuraminic acid (NANA) content of the four TBG bands isolated by preparative IEF was found to decrease from 10.2 mol NANA/mol TBG in the band at pH 4.25 to 4.8 mol NANA/mol TBG in the band at pH 4.55. No significant difference in the affinity constants of the TBG bands to T4 was found. The affinity constants for TBG ranged from 3.1 x 10(9) to 7.2 x 10(9) M-1. Sequential kinetic desialylation of pure TBG resulted in a progressive tendency toward one major band at pH 6.0. In native sera, microheterogeneity of TBG was detected after IEF on polyacrylamide gel plates by immunofixation. The typical TBG patterns shown by pure TBG were also found in normal subjects. Characteristic deviations from this pattern were found in the sera of females during estrogen therapy or pregnancy, where there was a gradual increase in density of the band at pH 4.25 and the appearance of an additional band at pH 4.15. In sera from patients with liver disease and elevated TBG levels, there was a fading of the acidic bands, whereas the more alkaline band at pH 4.55 was intensified. It is therefore proposed that microheterogeneity of TBG is caused by differences in NANA content and that variations of TBG patterns in native sera may reflect altered TBG synthesis or degradation. A genetically related microheterogeneity of TBG could not be demonstrated after examination of 800 sera, including 2 families with quantitative TBG deficiency
Katalogisierungskulturen in den USA und Deutschland – ein Vergleich / Comparing cataloging cultures in the US and Germany
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Unterschiedliche Traditionen. Ausblick in die Zukunft
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Modelling of Wastewater Heat Recovery Heat Pump Systems
Wastewater heat recovery is currently an underutilized technology that could be part of solving the climate crisis. A large portion of the heat that leaves a building in the form of wastewater is potentially recoverable for pre-heating domestic hot water or other service water systems. While there are several different approaches to wastewater heat recovery, this project focused on creating detailed, integrated building models for wastewater heat recovery heat pump systems. EnergyPlus models were developed featuring inputs and assumptions corresponding to manufacturers’ specifications, performance lab test data and feedback from engineering consultants. EnergyPlus’s supervisory control Energy Management System objects were heavily relied upon to overcome modelling challenges. The developed EnergyPlus model was integrated into U.S. Department of Energy New Construction Reference Building models for various climate zones and
building types to assess potential energy use, energy cost and greenhouse gas emission reductions
J004457+4123 (Sharov 21): not a remarkable nova in M31 but a background quasar with a spectacular UV flare
We announce the discovery of a quasar behind the disk of M31, which was
previously classified as a remarkable nova in our neighbour galaxy. The paper
is primarily aimed at the outburst of J004457+4123 (Sharov 21), with the first
part focussed on the optical spectroscopy and the improvement in the
photometric database. Both the optical spectrum and the broad band spectral
energy distribution of Sharov 21 are shown to be very similar to that of
normal, radio-quiet type 1 quasars. We present photometric data covering more
than a century and resulting in a long-term light curve that is densely sampled
over the past five decades. The variability of the quasar is characterized by a
ground state with typical fluctuation amplitudes of ~0.2 mag around B~20.5,
superimposed by a singular flare of ~2 yr duration (observer frame) with the
maximum at 1992.81 where the UV flux has increased by a factor of ~20. The
total energy in the flare is at least three orders of magnitudes higher than
the radiated energy of the most luminous supernovae, provided that it comes
from an intrinsic process and the energy is radiated isotropically. The profile
of the flare light curve appears to be in agreement with the standard
predictions for a stellar tidal disruption event where a ~10 M_sun giant star
was shredded in the tidal field of a ~2...5 10^8 M_sun black hole. The short
fallback time derived from the light curve requires an ultra-close encounter
where the pericentre of the stellar orbit is deep within the tidal disruption
radius. Gravitational microlensing provides an alternative explanation, though
the probability of such a high amplification event is very low.Comment: Accepted for publication in Astronomy and Astrophysics, 14 pages, 11
figure
Partial-Matching RMS Distance Under Translation: Combinatorics and Algorithms
We consider the problem of minimizing the RMS distance (sum of squared distances between pairs of points) under translation between two point sets A and B, in the plane, with (Formula presented.), in the partial-matching setup, in which each point in B is matched to a distinct point in A. Although the problem is not known to be polynomial, we establish several structural properties of the underlying subdivision (Formula presented.) of the plane and derive improved bounds on its complexity. Specifically, we show that this complexity is (Formula presented.), so it is only quadratic in |A|. These results lead to the best known algorithm for finding a translation for which the partial-matching RMS distance between the point sets is minimized. In addition, we show how to compute a local minimum of the partial-matching RMS distance under translation, in polynomial time. © 2017 Springer Science+Business Media New Yor
Film calibration for the Skylab/ATM S-056 X-ray telescope
The sensitometry and film calibration effort for the Skylab/ATM S-056 X-ray telescope is summarized. The apparatus and procedures used are described together with the two types of flight film used, Kodak SO-212 and SO-242. The sensitometry and processing of the flight film are discussed, and the results are presented in the form of the characteristic curves and related data. The use of copy films is also discussed
A phenomenological model for the X-ray spectrum of Nova V2491 Cygni
The X-ray flux of Nova V2491 Cyg reached a maximum some forty days after
optical maximum. The X-ray spectrum at that time, obtained with the RGS of
XMM-Newton, shows deep, blue-shifted absorption by ions of a wide range of
ionization. We show that the deep absorption lines of the X-ray spectrum at
maximum, and nine days later, are well described by the following
phenomenological model with emission from a central blackbody and from a
collisionally ionized plasma (CIE). The blackbody spectrum (BB) is absorbed by
three main highly-ionized expanding shells; the CIE and BB are absorbed by cold
circumstellar and interstellar matter that includes dust. The outflow density
does not decrease monotonically with distance. The abundances of the shells
indicate that they were ejected from an O-Ne white dwarf. We show that the
variations on time scales of hours in the X-ray spectrum are caused by a
combination of variation in the central source and in the column density of the
ionized shells. Our phenomenological model gives the best description so far of
the supersoft X-ray spectrum of nova V2491 Cyg, but underpredicts, by a large
factor, the optical and ultraviolet flux. The X-ray part of the spectrum must
originate from a very different layer in the expanding envelope, presumably
much closer to the white dwarf than the layers responsible for the
optical/ultraviolet spectrum. This is confirmed by absence of any correlation
between the X-ray and UV/optical observed fluxes.Comment: 11 pages, 6 figure
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