5,177 research outputs found

    Ultrasonic Lenses and Transmission Plates

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    Abstract Not Provided

    Coherence freeze in an optical lattice investigated via pump-probe spectroscopy

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    Motivated by our observation of fast echo decay and a surprising coherence freeze, we have developed a pump-probe spectroscopy technique for vibrational states of ultracold 85^{85}Rb atoms in an optical lattice to gain information about the memory dynamics of the system. We use pump-probe spectroscopy to monitor the time-dependent changes of frequencies experienced by atoms and to characterize the probability distribution of these frequency trajectories. We show that the inferred distribution, unlike a naive microscopic model of the lattice, correctly predicts the main features of the observed echo decay.Comment: 4 pages, 5 figure

    Faster, Smaller, Cheaper: An Hedonic Price Analysis of PDAs

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    We compute quality-adjusted price indexes for Personal Digital Assistants (PDAs) for the period 1999-2004, using data on prices and characteristics of 203 models sold by 12 manufacturers. The PDA market is growing in size, it is technologically dynamic with very substantial changes in measured characteristics over time, and it has experienced rapid rates of product introduction. Hedonic regressions consistently show prices to be positively related to processor performance, RAM memory, permanent storage capacity, and battery life, as well as several measures of screen size and quality. Features such as networking, biometric identification, camera, and cellphone capability are also positively associated with price. Hedonic price indexes implied by these regressions decline at an AAGR of 21.1% to 25.6% per year during this period. A matched model price index computed from a subset of observations declines at 18.75% per year. Though these PDA rates of price decline are lower than have been estimated for desktop and laptop PCs, consumers in this "ultra-portable" segment of the computer market appear to have enjoyed substantial welfare gains over the past five years.

    Rodents gone wild in the southeastern section of Missouri in the Peck Ranch Conservation Area

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    Abstract only availableManagement plans such as clear-cutting could affect the abundance of the species of rodents. The management of the forest can be responsible for the increasing or decreasing of rodent populations. I studied the rodents in the forest of the Peck Ranch Conservation Area to see if clear-cutting affected the populations. My study measured the abundance of rodents by observing their tracks in both clear-cut sites and no harvest sites. Rodents are important because they are another part of the ecosystem and can be hazardous if their population increases largely. They also though spread the plant seeds throughout the forest and keep some insects in check. I used metal rectangles about 1foot by 10inches, with clear plastic copy paper attached. I used an ink substance on the copy paper to imprint the tracks. To get the rodents to come, I used black sunflower seeds as bait. I put 10 in each the clear-cut and the no harvest site for 24hrs before recording the tracks observed.Missouri Ozark Forest Ecosystem Projec

    CARD In Situ hybridization: Sights and signals

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    During the last decade, several strategies have been developed to improve the detection sensitivity ofin situ hybridization (ISH) by amplification of either target nucleic acid sequences prior to ISH (e.g.,in situ PCR), or the detection signals after the hybridization procedures (signal amplification). Here we outline the principles of tyramide signal amplification using the catalyzed reporter deposition (CARD) technique, summarize applications as well as possible limitations of CARD ISH, and discuss some future directions ofin situ nucleic acid detection using this amplification strateg

    Quantum-Matter-Spacetime : Peter Mittelstaedt's Contributions to Physics and Its Foundations

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    In a period of over 50 years, Peter Mittelstaedt has made substantial and lasting contributions to several fields in theoretical physics as well as the foundations and philosophy of physics. Here we present an overview of his achievements in physics and its foundations which may serve as a guide to the bibliography (printed in this Festschrift) of his publications. An appraisal of Peter Mittelstaedt's work in the philosophy of physics is given in a separate contribution by B. Falkenburg

    The behavior of statically-indeterminate structural members and frames with cracks present

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    Arts et Métiers ParisTech, invitation en tant que professeur invité de Paul C. Paris au LAMEFIPCrack stability is discussed as affected by their presence in statically-indeterminate beams, frames, rings, etc. loaded into the plastic range. The stability of a crack in a section, which has become plastic, is analyzed with the remainder of the structure elastic and with subsequent additional plastic hinges occurring. The reduction of energy absorption characteristics for large deformations is also discussed. The methods of elastic–plastic tearing instability are incorporated to show that in many cases the fully plastic collapse mechanism must occur for complete failure.The authors acknowledge Arts et Metiers Paris Tech and Foundation Arts et Metiers for the financial support of the Prof. P.C. Paris’ stay at LAMEFIP in 2008 and 2009. The encouragement of Prof. Ivan Iordanoff, Director of LAMEFIP, is also acknowledged with thanks

    Pervasive Gaming: Testing Future Context Aware Applications

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    Over the last few years, many discussions have centred around the issue of interconnection rates and their economic impact on the market. Interconnection charging in Europe is still based mainly on the calling party pays (CPP) principle combined with element based charging (EBC). Due to the convergence of the classical PSTN/ISDN and the IP world to next generation networks (NGN), the different charging principles and systems are being reviewed to determine the optimal solution for the future. In its working program for the year 2008, the Austrian Regulatory Authority (RTR) launched an industry working group on charging principles and systems for wholesale services. This paper highlights some of the central issues of the discussions that have taken place and contains the authors’ views and conclusions .1 Further, the paper identifies possible charging systems, as well as economic assessment criteria for these systems and how the different charging systems may be evaluated with respect to those criteria. Regarding the usefulness of industry working groups, the work has shown that these lead to a higher degree of transparency between regulator and market players as well as a better understanding between the market players themselves. The main drawback is that working groups are time consuming and that it is almost impossible to agree on meaningful outcomes. Regarding the assessment of the charging models it was possible to derive a set of 10 criteria according to which charging systems can be evaluated. There was a rather broad consensus on the delineation of charging models as well as the economic criteria. When it comes to the results of the evaluation, the discussions brought forward very controversial views amongst the participants. No common views could be achieved on which the charging model fulfills the defined criteria in the best manner.Interconnection, NGN, charging principles, CPP, Bill&Keep.
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