4,852 research outputs found
Open charm meson spectroscopy: Where to place the latest piece of the puzzle
We discuss how to classify the meson recently
discovered by the BaBar Collaboration. We consider four possible assignments,
together with signatures useful to distinguish among them.Comment: RevTeX, 5 pages, 1 eps figur
Stability of Salpeter Solutions
In the framework of instantaneous approximations to the Bethe-Salpeter
formalism for the description of bound states within quantum field theories,
depending on the Lorentz structure of the Bethe-Salpeter interaction kernel the
solutions of the full Salpeter equation with some confining interaction may
exhibit certain instabilities, which are possibly related to the Klein paradox
and signal the decay of states assumed to be bound by the confining
interactions. They are observed in numerical (variational) studies of the
Salpeter equation. The presumably simplest scenario allowing for the fully
analytic investigation of this problem is set by the reduced Salpeter equation
with harmonic-oscillator interaction. In this case, Salpeter's integral
equation simplifies to either an algebraic relation or a second-order
homogeneous linear ordinary differential equation, immediately accessible to
standard techniques. There one may hope to be able to decide unambiguously
whether this setting poses a well-defined eigenvalue problem the solutions of
which correspond to stable bound states associated to real energy eigenvalues
bounded from below. By analytical spectral analysis the bound-state solutions
of this "harmonic-oscillator reduced Salpeter equation" can be shown to be free
of such instabilities.Comment: 6 pages, 2 figures, to appear in the Proceedings of "QCD @ Work
2007", International Workshop on Quantum ChromoDynamics - Theory and
Experiment, Martina Franca, Italy, 16 - 20 June 200
New insights into Chlamydiae persistence: an energy metabolism strategy?
Chlamydiaceae is a family of obligate intracellular bacteria generally considered energy parasites. Several studies have suggested that Chlamydiae are capable of independently producing energy and, more importantly, several genes involved in the energy metabolism are up-regulated during the persistent state. Thus, it has been suggested that chlamydial persistence could be a complex and flexible metabolic strategy designed to favor a lengthy survival in the host cell by evading the immune response. In conclusion, more detailed studies on the shift in the chlamydial energy metabolism, from the active to the persistent form, may be helpful in future to determine whether chlamydial persistence observed in vitro does occur in vivo and whether chronic sequelae of chlamydial diseases may be related to the persistence
Fermat hypersurfaces and Subcanonical curves
We extend the classical Enriques-Petri Theorem to -subcanonical
projectively normal curves, proving that such a curve is -gonal if and
only if it is contained in a surface of minimal degree. Moreover, we show that
any Fermat hypersurface of degree is apolar to an -subcanonical
-gonal projectively normal curve, and vice versa.Comment: 18 pages; AMS-LaTe
Barrier Paradox in the Klein Zone
We study the solutions for a one-dimensional electrostatic potential in the
Dirac equation when the incoming wave packet exhibits the Klein paradox (pair
production). With a barrier potential we demonstrate the existence of multiple
reflections (and transmissions). The antiparticle solutions which are
necessarily localized within the barrier region create new pairs with each
reflection at the potential walls. Consequently we encounter a new paradox for
the barrier because successive outgoing wave amplitudes grow geometrically.Comment: 10 page
Adaptation of Hybrid ANN/HMM Models using Linear Hidden Transformations and Conservative Training
International audienceA technique is proposed for the adaptation of automatic speech recognition systems using Hybrid models combining Artificial Neural Networks with Hidden Markov Models. The application of linear transformations not only to the input features, but also to the outputs of the internal layers is investigated. The motivation is that the outputs of an internal layer represent a projection of the input pattern into a space where it should be easier to learn the classification or transformation expected at the output of the network. A new solution, called Conservative Training, is proposed that compensates for the lack of adaptation samples in certain classes. Supervised adaptation experiments with different corpora and for different adaptation types are described. The results show that the proposed approach always outperforms the use of transformations in the feature space and yields even better results when combined with linear input transformations
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Destination Online Communication: Why Less is Sometimes More. A Study of Online Communications of English Destinations
This research investigates the relationship between Web site design and the Web site end-user experience of a vast number of English tourism destinations, both local and regional ones. Following recent research in the field, this paper evaluates destinations' online communication based on the implemented Web site features and on the effectiveness of the communication itself, borrowing its research methodology from different domains. After content and functionality analysis, a user-experience, scenario-based investigation has been carried out, which demonstrated that complex Web sites do not always serve end-users' needs properly; in other words, Web site complexity is not directly related with good user experience. This research may help destination managers to foster their online communication if they have fewer content and functionalities but are better focused and clearly user-oriented. © 2014 Taylor & Francis
Changes in private health service utilisation and access to the Italian National Health Service between 2006 and 2019: A cross-sectional comparative study
Objectives: Previous research highlighted that in the early 2000s a significant share of the Italian population used and paid out of pocket for private healthcare services even when they could potentially have received the same treatments from the National Health Service (NHS). The decrease in public investments in healthcare and the increase in health needs due to the population ageing may have modified the use of private health services and equity of access to the Italian NHS. This study aims to investigate the change in the prevalence of individuals who have fully paid out of pocket for accessing healthcare services in Italy between 2006 and 2019 and the main reasons behind this choice. Design: Cross-sectional comparative study. Participants and comparison: Two representative samples of the Italian population were collected in 2006 and 2019. Outcome measures: Prevalence of access to fully paid out-of-pocket private health services; type of service of the last fully paid out-of-pocket access; main reasons for the last fully paid out-of-pocket access. Results: We found an increase in the prevalence of people who declared having fully paid out of pocket at least one access to health services during their lifetime from 79.0% in 2006 to 91.9% in 2019 (adjusted OR 2.66; 95% CI 1.98 to 3.58). 'To avoid waiting times' was the main reason and it was significantly more frequent in 2019 compared with 2006 (adjusted OR 1.75; 95% CI 1.45 to 2.11). Conclusions: This comparative study, conducted the year before the outbreak of the COVID-19 pandemic, highlighted an increase in the prevalence of Italian residents who have fully paid out of pocket for access to health services to overcome long waiting times. Our findings may indicate a reduced access and possible worsening of the equity of access to the public and universalistic Italian NHS between 2006 and 2019
Partial purification and MALDI-TOF MS analysis of UN1, a tumor antigen membrane glycoprotein.
UN1 is a membrane glycoprotein that is expressed in immature human thymocytes, a subpopulation of peripheral T lymphocytes, the HPB acute lymphoblastic leukemia (ALL) T-cell line and fetal thymus. We previously reported the isolation of a monoclonal antibody (UN1 mAb) recognizing the UN1 protein that was classified as "unclustered" at the 5th and 6th International Workshop and Conference on Human Leukocyte Differentiation Antigens. UN1 was highly expressed in breast cancer tissues and was undetected in non-proliferative lesions and in normal breast tissues, indicating a role for UN1 in the development of a tumorigenic phenotype of breast cancer cells. In this study, we report a partial purification of the UN1 protein from HPB-ALL T cells by anion-exchange chromatography followed by immunoprecipitation with the UN1 mAb and MALDI-TOF MS analysis. This analysis should assist in identifying the amino acid sequence of UN
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