737 research outputs found

    Work fluctuation theorems for harmonic oscillators

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    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

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    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

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    We prove by degeneration to Prym-canonical binary curves that the first Gaussian map of the Prym canonical line bundle ωC⊗A\omega_C \otimes A 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

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    We measure the value of pharmaceutical drug innovations\textit{value of pharmaceutical drug innovations} 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

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    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.

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    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

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    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

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    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 c12c_1^2 and χ\chi. 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 M(x′,0,y)\mathcal M_{(x',0,y)} 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

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    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 Bi4Ge3O12{Bi}_4{Ge}_{3}{O}_{12}, CdWO4{CdWO}_{4} and ZnWO4{ZnWO}_{4}, in various mechanical configurations at room temperature and ambient pressure. We analyze how the light emission is correlated to acoustic emission during fracture. For Bi4Ge3O12{Bi}_4{Ge}_{3}{O}_{12}, 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 3×10−53 \times 10^{-5}
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