The excited-state photophysics of the light-induced antiviral agents hypericin and hypocrellin are compared with those of the hexa- and tetramethoxy analogues of hypericin. The results are consistent ...with the interpretation of the primary photoprocess in hypericin and hypocrellin as that of excited-state intramolecular proton or atom transfer.
We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1 μT magnetic field. We have demonstrated that the analysis of UCN spin-echo ...resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1 pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.
Session initiation protocol Zenner, Guy J.
Bell Labs technical journal,
Autumn (Fall) 2004, Letnik:
9, Številka:
3
Journal Article
Recenzirano
The way we communicate at work, at home, and while traveling is beginning to change significantly once again. Users are hungry for new converged Internet Protocol (IP) multimedia services driven by ...new user devices and the wider availability of broadband access networks. Many users want to be able to access a common set of services independent of how or where they initiate or receive a communication. New and traditional service providers are anxious to create offers with exciting new capabilities that use the innovative Internet paradigm to create converged voice, data, and video services. While many protocols will be used in next-generation communications networks, the Session initiation protocol (SIP) stands at the center of the new communications paradigm and is widely recognized as the primary communications protocol in evolving and next-generation networks.
Alcatel-Lucent is at the forefront of Application Enablement to strengthen service provider offerings. Project Neuron, one of the finalists of an Alcatel-Lucent Entrepreneurial boot camp held in ...North America (2009), proposes a set of pre-integrated capabilities called macro-enablers to achieve rapid creation of third party-developed applications that intelligently mash up with the mobile service provider network capabilities. We provide a perspective on the future of the communications industry and application stores. We also provide key highlights from Project Neuron and the estimated benefit of employing a risk/reward revenue model over standard business models, which are discussed in this letter. We conclude by proposing considerations on macro-enabler pricing approaches.
We compare the expected effects of so-called gravitationally enhanced depolarization of ultracold neutrons to measurements carried out in a spin-precession chamber exposed to a variety of vertical ...magnetic-field gradients. In particular, we have investigated the dependence upon these field gradients of spin depolarization rates and also of shifts in the measured neutron Larmor precession frequency. We find excellent qualitative agreement, with gravitationally enhanced depolarization accounting for several previously unexplained features in the data.
We report on the measurement of a Larmor frequency shift proportional to the electric-field strength for $^{199}{\rm Hg}$ atoms contained in a volume permeated with aligned magnetic and electric ...fields. This shift arises from the interplay between the inevitable magnetic field gradients and the motional magnetic field. The proportionality to electric-field strength makes it apparently similar to an electric dipole moment (EDM) signal, although unlike an EDM this effect is P- and T-conserving. We have used a neutron magnetic resonance EDM spectrometer, featuring a mercury co-magnetometer and an array of external cesium magnetometers, to measure the shift as a function of the applied magnetic field gradient. Our results are in good agreement with theoretical expectations.
New process stabilizers for polyolefins have been identified. 2-Aryl-1,3-dithianes, 2-aryl-1,3-dithiolanes and derivatives easily undergo H-atom abstraction, yielding a persistent benzyl-type free ...radical, and thus act as chain breaking stabilizers for polyolefins. Synergism with phenolic antioxidants and control of color development has been observed.
We are only in the early stages of voice over Internet Protocol (VoIP) deployments in large service provider networks. In most cases, these early deployments are limited in size and focus. In order ...to migrate toward large-scale use of VoIP in their networks, service providers are interested in leveraging their significant investment in the existing public switched telephone network (PSTN) infrastructure. Service providers want to evolve and transition their networks with minimal disruption to the existing working networks and without sacrificing service availability, quality, or the performance characteristics of these networks. While many interfaces and protocols need to be supported in the networks of the future, we see Session Initiation Protocol (SIP) as a key tool not only in building next-generation converged VoIP networks, but also in transitioning the PSTN to be an integral part of the VoIP networks. In this paper, we will show how the use of SIP and the addition of Internet Protocol (IP) interfaces to PSTN switches will enable service providers to capitalize more quickly on the new services and operating efficiencies available with converged VoIP networks.
We report on the measurement of a Larmor frequency shift proportional to the electric-field strength for
199
Hg atoms contained in a volume permeated with aligned magnetic and electric fields. This ...shift arises from the interplay between the inevitable magnetic field gradients and the motional magnetic field. The proportionality to electric-field strength makes it apparently similar to an electric dipole moment (EDM) signal, although unlike an EDM this effect is P- and T-conserving. We have used a neutron magnetic resonance EDM spectrometer, featuring a mercury co-magnetometer and an array of external cesium magnetometers, to measure the shift as a function of the applied magnetic field gradient. Our results are in good agreement with theoretical expectations.
Graphical abstract
Posttraumatic kyphosis (PTK) is a possible consequence of a missed fracture, a wrong indication for conservative therapy or an inadequate surgical technique but PTK can also be a complication after ...adequate surgery. Avoidance of PTK is of importance because subsequent surgical therapy can be extensive. A thorough planning as well as surgical experience with anterior and posterior revision cases is necessary. The various types of osteotomy which allow correction of local as well as global deformities should also be mastered. Knowledge of the principles of sagittal balance and spinopelvic parameters are indispensable in the treatment of PTK. Our experience and results from the literature show that a good long-term outcome with limited complications can only be achieved when considering the biomechanical principles as well as restoration of sagittal balance.
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