1,676 research outputs found
Exploiting citation networks for large-scale author name disambiguation
We present a novel algorithm and validation method for disambiguating author
names in very large bibliographic data sets and apply it to the full Web of
Science (WoS) citation index. Our algorithm relies only upon the author and
citation graphs available for the whole period covered by the WoS. A pair-wise
publication similarity metric, which is based on common co-authors,
self-citations, shared references and citations, is established to perform a
two-step agglomerative clustering that first connects individual papers and
then merges similar clusters. This parameterized model is optimized using an
h-index based recall measure, favoring the correct assignment of well-cited
publications, and a name-initials-based precision using WoS metadata and
cross-referenced Google Scholar profiles. Despite the use of limited metadata,
we reach a recall of 87% and a precision of 88% with a preference for
researchers with high h-index values. 47 million articles of WoS can be
disambiguated on a single machine in less than a day. We develop an h-index
distribution model, confirming that the prediction is in excellent agreement
with the empirical data, and yielding insight into the utility of the h-index
in real academic ranking scenarios.Comment: 14 pages, 5 figure
Characterization of cyclic nucleotide phosphodiesterase isoenzymes in the human ureter and their functional role in vitro
Effects of Ischemia on Lung Macrophages
Angiogenesis after pulmonary ischemia is initiated by reactive O2 species and is dependent on CXC chemokine growth factors, and its magnitude is correlated with the number of lavaged macrophages. After complete obstruction of the left pulmonary artery in mice, the left lung is isolated from the peripheral circulation until 5–7 days later, when a new systemic vasculature invades the lung parenchyma. Consequently, this model offers a unique opportunity to study the differentiation and/or proliferation of monocyte-derived cells within the lung. In this study, we questioned whether macrophage subpopulations were differentially expressed and which subset contributed to growth factor release. We characterized the change in number of all macrophages (MHCII int, CD11C+), alveolar macrophages (MHCII int, CD11C+, CD11B−) and mature lung macrophages (MHCII int, CD11C+, CD11B+) in left lungs from mice immediately (0 h) or 24 h after left pulmonary artery ligation (LPAL). In left lung homogenates, only lung macrophages increased 24 h after LPAL (vs. 0 h; p<0.05). No changes in proliferation were seen in any subset by PCNA expression (0 h vs. 24 h lungs). When the number of monocytic cells was reduced with clodronate liposomes, systemic blood flow to the left lung 14 days after LPAL decreased by 42% (p<0.01) compared to vehicle controls. Furthermore, when alveolar macrophages and lung macrophages were sorted and studied in vitro, only lung macrophages secreted the chemokine MIP-2α (ELISA). These data suggest that ischemic stress within the lung contributes to the differentiation of immature monocytes to lung macrophages within the first 24 h after LPAL. Lung macrophages but not alveolar macrophages increase and secrete the proangiogenic chemokine MIP-2α. Overall, an increase in the number of lung macrophages appears to be critical for neovascularization in the lung, since clodronate treatment decreased their number and attenuated functional angiogenesis
Spectral averaging techniques for Jacobi matrices with matrix entries
A Jacobi matrix with matrix entries is a self-adjoint block tridiagonal
matrix with invertible blocks on the off-diagonals. Averaging over boundary
conditions leads to explicit formulas for the averaged spectral measure which
can potentially be useful for spectral analysis. Furthermore another variant of
spectral averaging over coupling constants for these operators is presented
Results of a LMXB survey: variation in the height of the neutron star blackbody emission region
We present results of a survey of the spectra of Low Mass X-ray Binaries
using ASCA. It is shown that all sources in the survey are well-fitted by the
same two-component emission model that we have previously shown is able to
describe both the non-dip and dip spectra of the dipping class of LMXB. This
model consists of point-like blackbody emission from the neutron star plus
Comptonized emission from a disk-like accretion disk corona of radius typically
50,000 km. Additional data from results published elsewhere by us from BeppoSAX
and ASCA are added to the survey. The large variation in blackbody luminosity
of survey sources is shown to be due primarily to major changes in blackbody
emitting area. Fitting a multi-temperature disk blackbody plus Comptonization
model to the survey spectra requires values of inner disk radius substantially
less than the neutron star radius in many cases, making disk origin of the
blackbody highly unlikely. Assuming that the emission is from an equatorial
strip on the neutron star, it is shown that the half-height of the strip h
agrees well with the half-height H of the radiatively-supported inner accretion
disk, this agreement spanning three orders of magnitude in each parameter.
Possible mechanisms for the agreement are discussed, including radial accretion
flow between inner disk and star, and accretion flow ``creep' on the surface of
the neutron star.Comment: 10 pages, 7 ps figures; accepted for publication in A&A Main Journa
Endothelial preconditioning by transient oxidative stress reduces inflammatory responses of cultured endothelial cells to TNF-α
Brief episodes of ischemia can render an organ resistant to subsequent severe ischemia. This ‘ischemic preconditioning’ is ascribed to various mechanisms, including oxidative stress. We investigated whether preconditioning exists on an endothelial level. Human umbilical vein endothelial cells (HUVECs) were transiently confronted with oxidative stress (1 mM H2O2, 5 min). Adhesion molecules ICAM-1 and E-selectin and release of cytokines IL-6 and IL-8 to subsequent stimulation with TNF-α (2.5 ng/ml, 4 h) were measured (flow cytometry and immunoassay), as were nuclear translocation of the transcription factor NFkB (Western blotting, confocal microscopy) and redox status of HUVECs (quantification of glutathione by HPLC). TNF-α elevated IL-6 in the cell supernatant from 8.8 ± 1 to 41 ± 3 pg/ml and IL-8 from 0.5 ± 0.03 to 3 ± 0.2 ng/ml. ICAM-1 was increased threefold and E-selectin rose eightfold. Oxidative stress (decrease of glutathione by 50%) reduced post-TNF-α levels of IL-6 to 14 ± 3 and IL-8 to 1 ± 0.2; the rise of ICAM-1 was completely blocked and E-selectin was only doubled. The anti-inflammatory effects of preconditioning via oxidative stress were paralleled by reduction of the translocation of NFkB on stimulation with TNF-α, and antagonized by the intracellular radical scavenger N-acetylcysteine. ‘Anti-inflammatory preconditioning’ of endothelial cells by oxidative stress may account for the inhibitory effects of preconditioning on leukocyte adhesion in vivo
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Medical ethics in the Anthropocene: how are €100 billion of German physicians' pension funds invested?
[No abstract available
Random Dirac operators with time-reversal symmetry
Quasi-one-dimensional stochastic Dirac operators with an odd number of
channels, time reversal symmetry but otherwise efficiently coupled randomness
are shown to have one conducting channel and absolutely continuous spectrum of
multiplicity two. This follows by adapting the criteria of Guivarch-Raugi and
Goldsheid-Margulis to the analysis of random products of matrices in the group
SO, and then a version of Kotani theory for these operators. Absence of
singular spectrum can be shown by adapting an argument of Jaksic-Last if the
potential contains random Dirac peaks with absolutely continuous distribution.Comment: parts of introduction made more precise, corrections as follow-up on
referee report
Optical properties of c-Plane InGaN/GaN single quantum wells as a function of total electric field strength
We present low temperature photoluminescence spectra from four InGaN/GaN single quantum well structures where the total electric field across the quantum wells was varied by the manipulation of the surface polarization field, which is of opposite sign to the electrostatic built-in field originating from spontaneous and piezoelectric polarization intrinsic to the material. We find that, overall, the photoluminescence peak emission energy increases and its full width at half maximum decreases with decreasing total internal electric field. Using an atomistic tight-binding model of a quantum well with different total internal electric fields, we find that the calculated mean and standard deviation ground state transition energies follow the same trends with field as our experimentally determined spectral peak energies and widths. Overall, we attribute this behavior to a reduction in the quantum confined Stark effect and a connected reduction in the variation of ground state transition energies with decreasing electric field, respectively
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