746 research outputs found
Work fluctuation theorems for harmonic oscillators
The work fluctuations of an oscillator in contact with a thermostat and
driven out of equilibrium by an external force are studied experimentally and
theoretically within the context of Fluctuation Theorems (FTs). The oscillator
dynamics is modeled by a second order Langevin equation. Both the transient and
stationary state fluctuation theorems hold and the finite time corrections are
very different from those of a first order Langevin equation. The periodic
forcing of the oscillator is also studied; it presents new and unexpected short
time convergences. Analytical expressions are given in all cases
On the classification of OADP varieties
The main purpose of this paper is to show that OADP varieties stand at an
important crossroad of various main streets in different disciplines like
projective geometry, birational geometry and algebra. This is a good reason for
studying and classifying them. Main specific results are: (a) the
classification of all OADP surfaces (regardless to their smoothness); (b) the
classification of a relevant class of normal OADP varieties of any dimension,
which includes interesting examples like lagrangian grassmannians. Following
[PR], the equivalence of the classification in (b) with the one of
quadro-quadric Cremona transformations and of complex, unitary, cubic Jordan
algebras are explained.Comment: 13 pages. Dedicated to Fabrizio Catanese on the occasion of his 60th
birthday. To appear in a special issue of Science in China Series A:
Mathematic
On the first Gaussian map for Prym-canonical line bundles
We prove by degeneration to Prym-canonical binary curves that the first
Gaussian map of the Prym canonical line bundle is
surjective for the general point [C,A] of R_g if g >11, while it is injective
if g < 12.Comment: To appear in Geometriae Dedicata. arXiv admin note: text overlap with
arXiv:1105.447
Valuing Pharmaceutical Drug Innovations
We measure the by
estimating the market values of drugs and their development costs. We rely on
market responses to drug development announcements to identify the values and
costs. Using data on announcements by firms and their daily stock returns, we
estimate the average value of successful drugs at \$1.62 billion. At the
discovery stage, on average, drugs are valued at \$64.3 million and cost \$58.5
million. The average costs of the three phases of clinical trials are \$0.6,
\$30, and \$41 million, respectively. We also investigate applying these
estimates to policies supporting drug development
Simultaneous and accurate measurement of the dielectric constant at many frequencies spanning a wide range
We present an innovative technique which allows the simultaneous measurement
of the dielectric constant of a material at many frequencies, spanning a four
orders of magnitude range chosen between 10 --2 Hz and 10 4 Hz. The sensitivity
and accuracy are comparable to those obtained using standard single frequency
techniques. The technique is based on three new and simple features: a) the
precise real time correction of the amplication of a current amplier; b) the
specic shape of the excitation signal and its frequency spectrum; and c) the
precise synchronization between the generation of the excitation signal and the
acquisition of the dielectric response signal. This technique is useful in the
case of relatively fast dynamical measurements when the knowledge of the time
evolution of the dielectric constant is needed
Spinal anesthesia for cesarean delivery in a woman with neuromyelitis optica.
Neuromyelitis optica (NMO), or Devic's disease, is an idiopathic severe demyelinating disease that preferentially affects the optic nerve and spinal cord. Neuraxial anesthesia in women with multiple sclerosis is widely accepted, but reports of the use of neuraxial anesthesia in patients with NMO are scarce. We report the case of a morbidly obese primigravida undergoing a planned cesarean delivery at 32 weeks' gestation due to an acute exacerbation of NMO, managed with spinal anesthesia. Other than increased intraoperative hyperalgesia requiring inhaled nitrous oxide/oxygen, the mother experienced no apparent anesthetic-related complications
Extended Heat-Fluctuation Theorems for a System with Deterministic and Stochastic Forces
Heat fluctuations over a time \tau in a non-equilibrium stationary state and
in a transient state are studied for a simple system with deterministic and
stochastic components: a Brownian particle dragged through a fluid by a
harmonic potential which is moved with constant velocity. Using a Langevin
equation, we find the exact Fourier transform of the distribution of these
fluctuations for all \tau. By a saddle-point method we obtain analytical
results for the inverse Fourier transform, which, for not too small \tau, agree
very well with numerical results from a sampling method as well as from the
fast Fourier transform algorithm. Due to the interaction of the deterministic
part of the motion of the particle in the mechanical potential with the
stochastic part of the motion caused by the fluid, the conventional heat
fluctuation theorem is, for infinite and for finite \tau, replaced by an
extended fluctuation theorem that differs noticeably and measurably from it. In
particular, for large fluctuations, the ratio of the probability for absorption
of heat (by the particle from the fluid) to the probability to supply heat (by
the particle to the fluid) is much larger here than in the conventional
fluctuation theorem.Comment: 23 pages, 6 figures. Figures are now in color, Eq. (67) was corrected
and a footnote was added on the d-dimensional cas
Deformation of canonical morphisms and the moduli of surfaces of general type
In this article we study the deformation of finite maps and show how to use
this deformation theory to construct varieties with given invariants in a
projective space. Among other things, we prove a criterion that determines when
a finite map can be deformed to a one--to--one map. We use this criterion to
construct new simple canonical surfaces with different and . Our
general results enable us to describe some new components of the moduli of
surfaces of general type. We also find infinitely many moduli spaces having one component whose general point corresponds to a
canonically embedded surface and another component whose general point
corresponds to a surface whose canonical map is a degree 2 morphism.Comment: 32 pages. Final version with some simplifications and clarifications
in the exposition. To appear in Invent. Math. (the final publication is
available at springerlink.com
Sound and light from fractures in scintillators
Prompted by intriguing events observed in certain particle-physics searches
for rare events, we study light and acoustic emission simultaneously in some
inorganic scintillators subject to mechanical stress. We observe
mechanoluminescence in , and ,
in various mechanical configurations at room temperature and ambient pressure.
We analyze how the light emission is correlated to acoustic emission during
fracture. For , we set a lower bound on the energy of
the emitted light, and deduce that the fraction of elastic energy converted to
light is at least
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