1,086 research outputs found
How do Rating Agencies Score in Predicting Firm Performance
We use dynamic panel analysis to examine whether credit rating agencies achieve what they claim to achieve, namely, look into the future when assigning their ratings. We find that Moody's ratings help predict individual financial ratios over a horizon of up to five years. Ratings also predict a multivariate credit score, again over five years. The contribution of ratings appears to be economically significant and robust for different specifications.Credit Ratings, Predictive ability, Dynamic Panel Model.
Position matters : fluorescent positional isomers for reversible multichannel encryption devices
Fluorescence signals have been widely used in information encryption for a few decades, but still suffer from limited reliability. Here, reversible multichannel fluorescent devices with encrypted information were constructed, based on two fluorescent positional isomers of a diphenylquinoxaline derivative. Possessing the same core fluorescent group and acid-/pH-responsive mechanism, the two isomers showed different fluorescence color in an acidic environment, which allowed us to realize stepwise encryption of information in orthogonal fluorescence channels. Since the protonation was reversible, the revealed information could be re-encrypted, simply by heating. This approach highlights the value of positional isomers to build multichannel encryption devices, improving their reliability on the molecular level
Predatory short sales and bailouts
This paper extends the literature on predatory short selling and bailouts
through a joint analysis of the two. We consider a model with informed short
sales, as well as uninformed predatory short sales, which can trigger the inefficient
liquidation of a firm. We obtain several novel results: A government commitment
to bail out insolvent firms with positive probability can increase welfare because
it selectively deters predatory short selling without hampering desirable informed
short sales. Contrasting a common view, bailouts can be optimal ex ante but
undesirable ex post. Furthermore, bailouts in our model are a better policy tool
than short selling restrictions. Welfare gains from the bailout policy are unevenly
distributed: shareholders gain while taxpayers lose. Bailout taxes allow ex-ante
Pareto improvements
Nanolayer laser absorber for femtoliter chemistry in polymer reactors
Laser-induced forward transfer (LIFT) has the potential to be an alternative approach to atomic force microscopy based scanning probe lithography techniques, which have limitations in high-speed and large-scale patterning. However, traditional donor slides limit the resolution and chemical flexibility of LIFT. Here, we propose a hematite nanolayer absorber for donor slides to achieve high-resolution transfers down to sub-femtoliters. Being wettable by both aqueous and organic solvents, this new donor significantly increases the chemical scope for the LIFT process. For parallel amino acid coupling reactions, the patterning resolution can now be increased more than five times (>111,000 spots/cm2 for hematite donor versus 20,000 spots/cm2 for standard polyimide donor) with even faster scanning (2Â versus 6Â ms per spot). Due to the increased chemical flexibility, we could explore other types of reactions inside ultrasmall polymer reactors: copper (I) catalyzed click chemistry and laser-driven oxidation of a tetrahydroisoquinoline derivative, suggesting the potential of LIFT for both deposition of chemicals and laser-driven photochemical synthesis in femtoliters within milliseconds. Since the hematite shows no damage after typical laser transfer, donors can be regenerated by heat treatment. These findings will transform the LIFT process into an automatable, precise, and highly efficient technology for high-throughput femtoliter chemistry
Binding of endothelin to plasma proteins and tissue receptors: effects on endothelin determination, vasoactivity, and tissue kinetics
AbstractIn vitro binding of (3-[125I]Tyr)-endothelin-1 ([125I]ET-1) and (3-[125I]Tyr)-big ET-1(1â38) ([125I]big ET-1) to plasma proteins of healthy humans, cardiac patients and normotensive and hypertensive rats was investigated by equilibrium dialysis. Binding of both tracers was similar in plasma from healthy humans, patients with congestive heart failure, and following myocardial infarction (âŒ60%), and marginally higher in rat plasmas (âŒ70%). Binding of [125I]ET-1 to human plasma could be explained by binding to human serum albumin. Endogenous plasma ET-1 levels were âŒ9 pg/ml in healthy humans, and âŒ12â16 pg/ml in cardiac patients; big ET-1 concentrations were approximately two- to threefold higher. ET-1 bound to plasma protein was partly lost in column extraction. In rat isolated perfused hearts, the coronary dilator and constrictor potency of exogenous free and albumin-bound ET-1 was similar, whereas the kinetics of endogenous ET-1 was impeded by tight binding to ET receptors. The data indicate that binding of ET-1 to plasma proteins is without effect on peptide vasoactivity, but binding to tissue receptors greatly impedes its tissue kinetics
Diagnostic value of 18F-FDG-PET and PET-CT in children with fever of unknown origin or unexplained signs of inflammation
Halving Balls in Deterministic Linear Time
Let \D be a set of pairwise disjoint unit balls in and the
set of their center points. A hyperplane \Hy is an \emph{-separator} for
\D if each closed halfspace bounded by \Hy contains at least points
from . This generalizes the notion of halving hyperplanes, which correspond
to -separators. The analogous notion for point sets has been well studied.
Separators have various applications, for instance, in divide-and-conquer
schemes. In such a scheme any ball that is intersected by the separating
hyperplane may still interact with both sides of the partition. Therefore it is
desirable that the separating hyperplane intersects a small number of balls
only. We present three deterministic algorithms to bisect or approximately
bisect a given set of disjoint unit balls by a hyperplane: Firstly, we present
a simple linear-time algorithm to construct an -separator for balls
in , for any , that intersects at most
balls, for some constant that depends on and . The number of
intersected balls is best possible up to the constant . Secondly, we present
a near-linear time algorithm to construct an -separator in
that intersects balls. Finally, we give a linear-time algorithm to
construct a halving line in that intersects
disks.
Our results improve the runtime of a disk sliding algorithm by Bereg,
Dumitrescu and Pach. In addition, our results improve and derandomize an
algorithm to construct a space decomposition used by L{\"o}ffler and Mulzer to
construct an onion (convex layer) decomposition for imprecise points (any point
resides at an unknown location within a given disk)
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Multiple decisions about one object involve parallel sensory acquisition but time-multiplexed evidence incorporation.
Extended polarized semiclassical model for quantum-dot cavity QED and its application to single-photon sources
We present a simple extension of the semi-classical model for a two-level
system in a cavity, in order to incorporate multiple polarized transitions,
such as those appearing in neutral and charged quantum dots (QDs), and two
nondegenerate linearly polarized cavity modes. We verify the model by exact
quantum master equation calculations, and experimentally using a neutral QD in
a polarization non-degenerate micro-cavity, in both cases we observe excellent
agreement. Finally, the usefulness of this approach is demonstrated by
optimizing a single-photon source based on polarization postselection, where we
find an increase in the brightness for optimal polarization conditions as
predicted by the model.Comment: 8 pages, for simple code see https://doi.org/10.5281/zenodo.347666
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