11,519 research outputs found
Combining exclusive semi-leptonic and hadronic B decays to measure |V_ub|
The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| can be extracted from the
rate for the semi-leptonic decay B -> pi + l + antineutrino_l, with little
theoretical uncertainty, provided the hadronic form factor for the B -> pi
transition can be measured from some other B decay. In here, we suggest using
the decay B -> pi J\psi. This is a color suppressed decay, and it cannot be
properly described within the usual factorization approximation; we use instead
a simple and very general phenomenological model for the b d J\psi vertex. In
order to relate the hadronic form factors in the B -> pi J\psi and B -> pi + l
+ antineutrino_l decays, we use form factor relations that hold for
heavy-to-light transitions at large recoil.Comment: Latex, 7 pages, no figure
Nonfactorization and Color-Suppressed Decays
Using value of the parameter but including a modest
nonfactorized amplitude, we show that it is possible to understand all data,
including polarization, for color-suppressed
decays in all commonly used models of form factors. We show that for decay one can define an effective , which is process-dependent and,
in general, complex; but it is not possible to define an effective for
decay. We also explain why nonfactorized amplitudes do not
play a significant role in color-favored B decays.Comment: 13 pages, Latex, one figure (not included
CONTAINER FOR THE TRANSPORTATION AND CONSERVATION OF IMMUNOBIOLOGICALS
A container was developed for the transport and conservation of immunological products under low temperatures of between 2 and 8 º C, within a time span of 8 hours. The container is practical, simple and userfriendly, and can be used in places without electric power, and all these advantages are added of low operational costs. The container proposed aims at meeeting the demand of the Programa Nacional de Imunizações (PNI- the National Immunization Program), through Cold Chain, which sets the standards for all the procedures concerning conservation, handling, distribution and transport of the vaccine from the laboratory that produces it to the moment of inoculation.Innitially, the container was specifically developed for Vaccine for Inactive Influenza Virus against flu, which, according to a survey conducted with laboratories, is the most widely consumed, and whose conservation time span is also applicable to other immunobiologicals After the design and construction of the prototype, the container was exhaustively tested under different weather conditions. The results of the experiment are being exposed and discussed in this paper and the prototype lived up to the expectations of the reserachers in terms of the time spans and temperatures foreseen for the conservation of the vaccine selected
Nonfactorization in Hadronic Two-body Cabibbo-favored decays of D^0 and D^+
With the inclusion of nonfactorized amplitudes in a scheme with , we
have studied Cabibbo-favored decays of and into two-body hadronic
states involving two isospins in the final state. We have shown that it is
possible to understand the measured branching ratios and determined the sizes
and signs of nonfactorized amplitudes required.Comment: 15 pages, Late
Sequential Extensions of Causal and Evidential Decision Theory
Moving beyond the dualistic view in AI where agent and environment are
separated incurs new challenges for decision making, as calculation of expected
utility is no longer straightforward. The non-dualistic decision theory
literature is split between causal decision theory and evidential decision
theory. We extend these decision algorithms to the sequential setting where the
agent alternates between taking actions and observing their consequences. We
find that evidential decision theory has two natural extensions while causal
decision theory only has one.Comment: ADT 201
Form factor relations for heavy-to-heavy and heavy-to-light meson transitions
Relations between the form factors that parametrize the hadronic matrix
elements, in spectator decays of heavy mesons, have been derived by Stech
within the constituent quark model. In here, we examine these relations using a
slightly modified description of the meson states. We find new and very general
relations for some of the form factors. For the other form factors, we obtain
small modifications to the relations previously derived by Stech, in the case
of heavy-to-light transitions.Comment: 13 pages, LaTex, 2 figure
Objective quality prediction model for lost frames in 3D video over TS
This paper proposes an objective model to predict the quality of lost frames in 3D video streams. The model is based only on header information from three different packet-layer levels: Network Abstraction Layer (NAL), Packetised Elementary Streams (PES) and Transport Stream (TS). Transmission errors leading to undecodable TS packets are assumed to result in frame loss. The proposed method estimates the size of the lost frames, which is used as a model parameter to predict their objective quality measured as the Structural Similarity Index Metric (SSIM). The results show that SSIM of missing stereoscopic frames in 3D coded video can be predicted with Root Mean Square Error (RMSE) accuracy of about 0.1 and Pearson correlation coefficient of 0.8, taking the SSIM of uncorrupted frames as reference. It is concluded that the proposed model is capable of estimating the SSIM quite accurately using only the lost frames estimated sizes.info:eu-repo/semantics/acceptedVersio
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