3,324 research outputs found
On Equilibrium Prices in Continuous Time
We combine general equilibrium theory and theorie generale of stochastic
processes to derive structural results about equilibrium state prices
On equilibrium prices in continuous time
We combine general equilibrium theory and théorie générale of stochastic processes to derive structural results about equilibrium state prices.general equilibrium, continuous time finance, théorie générale of stochastic processes, asset pricing, state prices
Understanding of the phase transformation from fullerite to amorphous carbon at the microscopic level
We have studied the shock-induced phase transition from fullerite to a dense
amorphous carbon phase by tight-binding molecular dynamics. For increasing
hydrostatic pressures P, the C60-cages are found to polymerise at P<10 GPa, to
break at P~40 GPa and to slowly collapse further at P>60 GPa. By contrast, in
the presence of additional shear stresses, the cages are destroyed at much
lower pressures (P<30 GPa). We explain this fact in terms of a continuum model,
the snap-through instability of a spherical shell. Surprisingly, the relaxed
high-density structures display no intermediate-range order.Comment: 5 pages, 3 figure
Polaron Recombination in Pristine and Annealed Bulk Heterojunction Solar Cells
The major loss mechanism of photogenerated polarons was investigated in
P3HT:PCBM solar cells by the photo-CELIV technique. For pristine and annealed
devices, we find that the experimental data can be explained by a bimolecular
recombination rate reduced by a factor of about ten (pristine) and 25
(annealed) as compared to Langevin theory. Aided by a macroscopic device model,
we discuss the implications of the lowered loss rate on the characteristics of
polymer:fullerene solar cells.Comment: 3 pages, 4 figure
A matrix isolation and computational study of molecular palladium fluorides : does PdF₆ exist?
Palladium atoms generated by thermal evaporation and laser ablation were reacted with and trapped in F₂ /Ar, F₂ /Ne, and neat F₂ matrices. The products were characterized by electronic absorption and infrared spectroscopy, together with relativistic density functional theory calculations as well as coupled cluster calculations. Vibrational modes at 540 and 617 cm⁻¹ in argon matrices were assigned to molecular PdF and PdF₂ , and a band at 692 cm⁻¹ was assigned to molecular PdF₄ . A band at 624 cm⁻¹ can be assigned to either PdF₃ or PdF₆, with the former preferred from experimental considerations. Although calculations might support the latter assignment, our conclusion is that in these detailed experiments there is no convincing evidence for PdF₆
Evidence for magnetoplasmon character of the cyclotron resonance response of a two-dimensional electron gas
Experimental results on the absolute magneto-transmission of a series of high
density, high mobility GaAs quantum wells are compared with the predictions of
a recent magnetoplasmon theory for values of the filling factor above 2. We
show that the magnetoplasmon picture can explain the non-linear features
observed in the magnetic field evolution of the cyclotron resonance energies
and of the absorption oscillator strength. This provides experimental evidence
that inter Landau level excitations probed by infrared spectroscopy need to be
considered as many body excitations in terms of magnetoplasmons: this is
especially true when interpreting the oscillator strengths of the cyclotron
transitions
Producing translationally cold, ground-state CO molecules
Carbon monoxide molecules in their electronic, vibrational, and rotational
ground state are highly attractive for trapping experiments. The optical or ac
electric traps that can be envisioned for these molecules will be very shallow,
however, with depths in the sub-milliKelvin range. Here we outline that the
required samples of translationally cold CO (X, =0, =0)
molecules can be produced after Stark deceleration of a beam of laser-prepared
metastable CO (a) molecules followed by optical transfer of the
metastable species to the ground state \emph{via} perturbed levels in the
A state. The optical transfer scheme is experimentally demonstrated and
the radiative lifetimes and the electric dipole moments of the intermediate
levels are determined
Towards designing robust coupled networks
Natural and technological interdependent systems have been shown to be highly
vulnerable due to cascading failures and an abrupt collapse of global
connectivity under initial failure. Mitigating the risk by partial
disconnection endangers their functionality. Here we propose a systematic
strategy of selecting a minimum number of autonomous nodes that guarantee a
smooth transition in robustness. Our method which is based on betweenness is
tested on various examples including the famous 2003 electrical blackout of
Italy. We show that, with this strategy, the necessary number of autonomous
nodes can be reduced by a factor of five compared to a random choice. We also
find that the transition to abrupt collapse follows tricritical scaling
characterized by a set of exponents which is independent on the protection
strategy
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