26,664 research outputs found

    Operations and single particle interferometry

    Full text link
    Interferometry of single particles with internal degrees of freedom is investigated. We discuss the interference patterns obtained when an internal state evolution device is inserted into one or both the paths of the interferometer. The interference pattern obtained is not uniquely determined by the completely positive maps (CPMs) that describe how the devices evolve the internal state of a particle. By using the concept of gluing of CPMs, we investigate the structure of all possible interference patterns obtainable for given trace preserving internal state CPMs. We discuss what can be inferred about the gluing, given a sufficiently rich set of interference experiments. It is shown that the standard interferometric setup is limited in its abilities to distinguish different gluings. A generalized interferometric setup is introduced with the capacity to distinguish all gluings. We also connect to another approach using the well known fact that channels can be realized using a joint unitary evolution of the system and an ancillary system. We deduce the set of all such unitary `representations' and relate the structure of this set to gluings and interference phenomena.Comment: Journal reference added. Material adde

    Absence of reflection as a function of the coupling constant

    Full text link
    We consider solutions of the one-dimensional equation −u′′+(Q+λV)u=0-u'' +(Q+ \lambda V) u = 0 where Q:R→RQ: \mathbb{R} \to \mathbb{R} is locally integrable, V:R→RV : \mathbb{R} \to \mathbb{R} is integrable with supp(V)⊂[0,1](V) \subset [0,1], and λ∈R\lambda \in \mathbb{R} is a coupling constant. Given a family of solutions {uλ}λ∈R\{u_{\lambda} \}_{\lambda \in \mathbb{R}} which satisfy uλ(x)=u0(x)u_{\lambda}(x) = u_0(x) for all x<0x<0, we prove that the zeros of b(λ):=W[u0,uλ]b(\lambda) := W[u_0, u_{\lambda}], the Wronskian of u0u_0 and uλu_{\lambda}, form a discrete set unless V≡0V \equiv 0. Setting Q(x):=−EQ(x) := -E, one sees that a particular consequence of this result may be stated as: if the fixed energy scattering experiment −u′′+λVu=Eu-u'' + \lambda V u = Eu gives rise to a reflection coefficient which vanishes on a set of couplings with an accumulation point, then V≡0V \equiv 0.Comment: To appear in Journal of Mathematical Physic

    Fast transform decoding of nonsystematic Reed-Solomon codes

    Get PDF
    A Reed-Solomon (RS) code is considered to be a special case of a redundant residue polynomial (RRP) code, and a fast transform decoding algorithm to correct both errors and erasures is presented. This decoding scheme is an improvement of the decoding algorithm for the RRP code suggested by Shiozaki and Nishida, and can be realized readily on very large scale integration chips

    Preliminary catalog of pictures taken on the lunar surface during the Apollo 16 mission

    Get PDF
    A catalog of all pictures taken from the lunar module or the lunar surface during the Apollo 16 lunar stay is presented. The tabulations are arranged for the following specific uses: (1) given the number of a particular frame, find its location in the sequence of lunar surface activity, the station from which it was taken and the subject matter of the picture; (2) given a particular location or activity within the sequence of lunar surface activity, find the pictures taken at that time and their subject matter; and (3) given a sample number from the voice transcript listed, find the designation assigned to the same sample by the lunar receiving laboratory

    The Effects of De-Training and Re-Training the Cardiovascular and Respiratory Systems on Female Collegiate Swimmers

    Get PDF
    Please refer to the pdf version of the abstract located adjacent to the title

    Assessment of fish populations and habitat on Oculina Bank, a deep-sea coral marine protected area off eastern Florida

    Get PDF
    A portion of the Oculina Bank located off eastern Florida is a marine protected area (MPA) preserved for its dense populations of the ivory tree coral (Oculina varicosa), which provides important habitat for fish. Surveys of fish assemblages and benthic habitat were conducted inside and outside the MPA in 2003 and 2005 by using remotely operated vehicle video transects and digital still imagery. Fish species composition, biodiversity, and grouper densities were used to determine whether O. varicosa forms an essential habitat compared to other structure-forming habitats and to examine the effectiveness of the MPA. Multivariate analyses indicated no differences in fish assemblages or biodiversity among hardbottom habitat types and grouper densities were highest among the most complex habitats; however the higher densities were not exclusive to coral habitat. Therefore, we conclude that O. varicosa was functionally equivalent to other hardbottom habitats. Even though fish assemblages were not different among management areas, biodiversity and grouper densities were higher inside the MPA compared to outside. The percentage of intact coral was also higher inside the MPA. These results provide initial evidence demonstrating effectiveness of the MPA for restoring reef fish and their habitat. This is the first study to compare reef fish populations on O. varicosa with other structure-forming reef habitats and also the first to examine the effectiveness of the MPA for restoring fish populations and live reef cover

    A new result on the Klein-Gordon equation in the background of a rotating black hole

    Full text link
    This short paper should serve as basis for further analysis of a previously found new symmetry of the solutions of the wave equation in the gravitational field of a Kerr black hole. Its main new result is the proof of essential self-adjointness of the spatial part of a reduced normalized wave operator of the Kerr metric in a weighted L^2-space. As a consequence, it leads to a purely operator theoretic proof of the well-posedness of the initial value problem of the reduced Klein-Gordon equation in that field in that L^2-space and in this way generalizes a corresponding result of Kay (1985) in the case of the Schwarzschild black hole. It is believed that the employed methods are applicable to other separable wave equations

    Patients as researchers - innovative experiences in UK National Health Service research

    Get PDF
    Consumer involvement is an established priority in UK health and social care service development and research. To date, little has been published describing the process of consumer involvement and assessing ‘consumers’ contributions to research. This paper provides a practical account of the effective incorporation of consumers into a research team, and outlines the extent to which they can enhance the research cycle; from project development and conduct, through data analysis and interpretation, to dissemination. Salient points are illustrated using the example of their collaboration in a research project. Of particular note were consumers’ contributions to the development of an ethically enhanced, more robust project design, and enriched data interpretation, which may not have resulted had consumers not been an integral part of the research team

    A VLSI design for a systolic Viterbi decoder

    Get PDF
    A systolic Viterbi decoder for convolutional codes is developed. This decoder uses the trace-back method to reduce the amount of data needed to be stored in registers. It is shown that this new algorithm requires a smaller chip size and achieves a faster decoding time than other existing methods

    Bose Einstein condensation on inhomogeneous amenable graphs

    Full text link
    We investigate the Bose-Einstein Condensation on nonhomogeneous amenable networks for the model describing arrays of Josephson junctions. The resulting topological model, whose Hamiltonian is the pure hopping one given by the opposite of the adjacency operator, has also a mathematical interest in itself. We show that for the nonhomogeneous networks like the comb graphs, particles condensate in momentum and configuration space as well. In this case different properties of the network, of geometric and probabilistic nature, such as the volume growth, the shape of the ground state, and the transience, all play a role in the condensation phenomena. The situation is quite different for homogeneous networks where just one of these parameters, e.g. the volume growth, is enough to determine the appearance of the condensation.Comment: 43 pages, 12 figures, final versio
    • …
    corecore