191 research outputs found
The Role of Institutional Investors in Corporate Finance
This paper argues that institutional investors may have a positive effect on stock prices. This effect realizes through different mechanisms: institutional investors reduce information asymmetries between firms and (other) investors, contribute to the liquidity of the company’s stock and improve its corporate governance. We conjecture that firms, understanding the benefits of having institutional investors in their ownership, may do efforts to attract them. We apply this idea in the context of IPOs. Using data on Belgian IPOs over the period 1984-2000, we find that firms using the stock market as a financing vehicle and firms less likely to be monitored by corporate blockholders are more likely to pre-allocate shares to institutional investors at IPO-time. Finally, pre-allocating shares to institutional investors is shown to reduce underpricing and enhance post-IPO liquidity.
Higher Order Decompositions of Ordered Operator Exponentials
We present a decomposition scheme based on Lie-Trotter-Suzuki product
formulae to represent an ordered operator exponential as a product of ordinary
operator exponentials. We provide a rigorous proof that does not use a
time-displacement superoperator, and can be applied to non-analytic functions.
Our proof provides explicit bounds on the error and includes cases where the
functions are not infinitely differentiable. We show that Lie-Trotter-Suzuki
product formulae can still be used for functions that are not infinitely
differentiable, but that arbitrary order scaling may not be achieved.Comment: 16 pages, 1 figur
Spin communication over 30 m long channels of chemical vapor deposited graphene on SiO
We demonstrate a high-yield fabrication of non-local spin valve devices with
room-temperature spin lifetimes of up to 3 ns and spin relaxation lengths as
long as 9 m in platinum-based chemical vapor deposition (Pt-CVD)
synthesized single-layer graphene on SiO/Si substrates. The spin-lifetime
systematically presents a marked minimum at the charge neutrality point, as
typically observed in pristine exfoliated graphene. However, by studying the
carrier density dependence beyond n ~ 5 x 10 cm, via
electrostatic gating, it is found that the spin lifetime reaches a maximum and
then starts decreasing, a behavior that is reminiscent of that predicted when
the spin-relaxation is driven by spin-orbit interaction. The spin lifetimes and
relaxation lengths compare well with state-of-the-art results using exfoliated
graphene on SiO/Si, being a factor two-to-three larger than the best values
reported at room temperature using the same substrate. As a result, the spin
signal can be readily measured across 30 m long graphene channels. These
observations indicate that Pt-CVD graphene is a promising material for
large-scale spin-based logic-in-memory applications
Analyse du risque posé en santé animale par la présence de l'hydroxyméthylfurfural dans les sirops de nourrissement des abeilles domestiques
This paper discusses an incident that occurred in Belgium during winter 2009-2010, after which many honey bee colonies have been lost. Later analyses showed that these colonies had been fed during the winter with a inverted sugar syrup from sugar beet which had a high concentration of hydroxymethylfurfural (HMF). HMF concentrations ranged from 18.8 ppm to 365.6 ppm. Data from the scientific literature are quite limited, but several authors confirm the harmful effect of HMF on honey bee health. Other elements, however, may have played a role in this apparent mortality such as crystallization of syrups, resulting in unavailability of sugar for the honey bees, and thus the death of them from starvation. Pending the acquisition of new scientific knowledge on the subject, it is recommended to follow good beekeeping practices detailed in this article to minimize the formation of HMF in syrups for honey bee feeding. In addition, a draft action limit corresponding to a maximal concentration of 40 ppm of HMF is proposed in order to control the risk at the producer and distributor of syrups for honey bee feeding level
Prospects for hybrid integration of Si and SiN waveguides with graphene and other 2D-materials
Complex effective index in graphene-silicon waveguides
We report for the first time and characterize experimentally the complex optical
conductivity of graphene on silicon photonic waveguides. This permits us to predict
accurately the behavior of photonic integrated devices encompassing graphene layers.
Exploiting a Si microring add/drop resonator, we show the effect of electrical gating of
graphene on the complex effective index of the waveguide by measuring both the wavelength
shift of the resonance and the change in the drop peak transmission. Due to electro-refractive
effect of graphene a giant (>10 123) change in the effective index is demonstrated for the first
time on Si photonics waveguides and this large effect will crucially impact performances and
consumption of Si photonics devices. We confirmed the results by two independent
experiments involving two different gating schemes: Si gating through the ridge waveguide,
and polymer-electrolyte gating. Both the experiments demonstrate a very large phase effect in
good agreement with numerical calculations. The reported results validate the Kubo model
for the case of graphene-Si photonics interfaces and for propagation in this type of
waveguide. This is fundamental for the next design and fabrication of future graphene-silicon
photonics devices
How and when does personal life orientation predict well-being?
Abstract
We examined the direct and indirect––as mediated by job satisfaction––effects of personal life orientation on life satisfaction. We also examined whether these direct and indirect associations differed between employees working onsite or remotely. Using data from 432 employees (152 working onsite and 280 working remotely), our results revealed that personal life orientation was positively related to life satisfaction and negatively related to job satisfaction. Moreover, both of these direct associations were stronger among onsite employees than among remote employees. As a result, the indirect effects of personal life orientation on life satisfaction were significantly mediated by job satisfaction among employees working onsite, but not among employees working remotely. This study thus reveals that working remotely may act as a double-edged sword by buffering the negative effects of personal life orientation on job satisfaction, but also by limiting the positive effects of personal life orientation on life satisfaction
Recommended from our members
The future of auroral E-region plasma turbulence research
The heating caused by ionospheric E-region plasma turbulence has documented global implications for the energy transfer from space into the terrestrial atmosphere. Traveling atmospheric disturbances, neutral wind motion, energy deposition rates, and ionospheric conductance have all been shown to be potentially affected by turbulent plasma heating. Therefore it is proposed to enhance and expand existing ionospheric radar capabilities and fund research into E-region plasma turbulence so that it is possible to more accurately quantify the solar-terrestrial energy budget and study phenomena related to E-region plasma turbulence. The proposed research funding includes the development of models to accurately predict and model the E-region plasma turbulence using particle-in-cell analysis, fluid-based analysis, and hybrid combinations of the two. This review provides an expanded and more detailed description of the past, present, and future of auroral E-region plasma turbulence research compared to the summary report submitted to the National Academy of Sciences Decadal Survey for Solar and Space Physics (Heliophysics) 2024–2033 (Huyghebaert et al., 2022a)
On quantum mean-field models and their quantum annealing
This paper deals with fully-connected mean-field models of quantum spins with
p-body ferromagnetic interactions and a transverse field. For p=2 this
corresponds to the quantum Curie-Weiss model (a special case of the
Lipkin-Meshkov-Glick model) which exhibits a second-order phase transition,
while for p>2 the transition is first order. We provide a refined analytical
description both of the static and of the dynamic properties of these models.
In particular we obtain analytically the exponential rate of decay of the gap
at the first-order transition. We also study the slow annealing from the pure
transverse field to the pure ferromagnet (and vice versa) and discuss the
effect of the first-order transition and of the spinodal limit of metastability
on the residual excitation energy, both for finite and exponentially divergent
annealing times. In the quantum computation perspective this quantity would
assess the efficiency of the quantum adiabatic procedure as an approximation
algorithm.Comment: 44 pages, 23 figure
- …