28,149 research outputs found

    Detection of Exotic Massive Hadrons in Ultra High Energy Cosmic Ray Telescopes

    Full text link
    We investigate the detection of exotic massive strongly interacting hadrons (uhecrons) in ultra high energy cosmic ray telescopes. The conclusion is that experiments such as the Pierre Auger Observatory have the potential to detect these particles. It is shown that uhecron showers have clear distinctive features when compared to proton and nuclear showers. The simulation of uhecron air showers, and its detection and reconstruction by fluorescence telescopes is described. We determine basic cuts in observables that will separate uhecrons from the cosmic ray bulk, assuming this is composed by protons. If these are composed by heavier nucleus the separation will be much improved. We also discuss photon induced showers. The complementarity between uhecron detection in accelerator experiments is discussed.Comment: 9 page 9 figure

    An evolutionary perspective on the kinome of malaria parasites

    Get PDF
    Malaria parasites belong to an ancient lineage that diverged very early from the main branch of eukaryotes. The approximately 90-member plasmodial kinome includes a majority of eukaryotic protein kinases that clearly cluster within the AGC, CMGC, TKL, CaMK and CK1 groups found in yeast, plants and mammals, testifying to the ancient ancestry of these families. However, several hundred millions years of independent evolution, and the specific pressures brought about by first a photosynthetic and then a parasitic lifestyle, led to the emergence of unique features in the plasmodial kinome. These include taxon-restricted kinase families, and unique peculiarities of individual enzymes even when they have homologues in other eukaryotes. Here, we merge essential aspects of all three malaria-related communications that were presented at the Evolution of Protein Phosphorylation meeting, and propose an integrated discussion of the specific features of the parasite's kinome and phosphoproteome

    Construction of SU(3) irreps in canonical SO(3)-coupled bases

    Full text link
    Alternative canonical methods for defining canonical SO(3)-coupled bases for SU(3) irreps are considered and compared. It is shown that a basis that diagonalizes a particular linear combination of SO(3) invariants in the SU(3) universal enveloping algebra gives basis states that have good KK quantum numbers in the asymptotic rotor-model limit.Comment: no figure

    Photometric Properties of 47 Clusters of Galaxies: I. The Butcher-Oemler Effect

    Get PDF
    We present gri CCD photometry of 44 Abell clusters and 4 cluster candidates. Twenty one clusters in our sample have spectroscopic redshifts. Fitting a relation between mean g, r and i magnitudes, and redshift for this subsample, we have calculated photometric redshifts for the remainder with an estimated accuracy of 0.03. The resulting redshift range for the sample is 0.03<z<0.38. Color-magnitude diagrams are presented for the complete sample and used to study evolution of the galaxy population in the cluster environment. Our observations show a strong Butcher-Oemler effect (Butcher & Oemler 1978, 1984), with an increase in the fraction of blue galaxies (f_B) with redshift that seems more consistent with the steeper relation estimated by Rakos and Schombert (1995) than with the original one by Butcher & Oemler (1984). However, in the redshift range between ~ 0.08 and 0.2, where most of our clusters lie, there is a wide range of f_B values, consistent with no redshift evolution of the cluster galaxy population. A large range of f_B values is also seen between ~ 0.2 and 0.3, when Smail at al. (1998) x-ray clusters are added to our sample. The discrepancies between samples underscore the need for an unbiased sample to understand how much of the Butcher-Oemler effect is due to evolution, and how much to selection effects. We also tested the idea proposed by Garilli et al. (1996) that there is a population of unusually red galaxies which could be associated either with the field or clusters, but we find that these objects are all near the limiting magnitude of the images (20.5<r<22) and have colors that are consistent with those expected for stars or field galaxies at z ~ 0.7.Comment: 35 pages including 8 figures, submitted to A

    Self-organized patterns of coexistence out of a predator-prey cellular automaton

    Full text link
    We present a stochastic approach to modeling the dynamics of coexistence of prey and predator populations. It is assumed that the space of coexistence is explicitly subdivided in a grid of cells. Each cell can be occupied by only one individual of each species or can be empty. The system evolves in time according to a probabilistic cellular automaton composed by a set of local rules which describe interactions between species individuals and mimic the process of birth, death and predation. By performing computational simulations, we found that, depending on the values of the parameters of the model, the following states can be reached: a prey absorbing state and active states of two types. In one of them both species coexist in a stationary regime with population densities constant in time. The other kind of active state is characterized by local coupled time oscillations of prey and predator populations. We focus on the self-organized structures arising from spatio-temporal dynamics of the coexistence. We identify distinct spatial patterns of prey and predators and verify that they are intimally connected to the time coexistence behavior of the species. The occurrence of a prey percolating cluster on the spatial patterns of the active states is also examined.Comment: 19 pages, 11 figure

    Medical Escort of Critical Care Patients in the Pre-Hospital Setting

    Get PDF
    Introduction: Pre-hospital emergency cases include the patient’s transportation to the hospital, with an adequate escort, when indicated. In Portugal, secondary transport’s escort is guided by an escort score published by the Portuguese Medical Association’s Guidelines on the Critical Care Patient’s Transport (2008). This score (TS) defines three levels of escort: no medical escort (level A), doctor or nurse escort (level B), doctor and nurse escort (level C). There is no published data on this score’s application to the pre-hospital setting. Such use could improve resource management in the pre-hospital emergency medical services, as it could support the need to involve a doctor and/or nurse in the patient’s escort to the hospital. Our study’s aim is the evaluate the TS application to the pre-hospital context. Study Methods: We gathered data from primary transports’ escorts between January 2015 and January 2017. We recorded whether the patient was taken to hospital or not, and if yes, the transport’s escort (Doctor, Doctor and Nurse, or only emergency technicians). Posteriorly, we calculated the TS for each of those transport records. Any records with incomplete escort data or where the score could not be calculated were excluded. Using this data, we calculated Sensibility (Ss), Specificity (Sp), positive predicitive value (PPV) and negative predictive value (NPV) of the TS for the following situations: Escort by emergency technicians only (level A), escort by doctor or nurse (level B) or escort by doctor and nurse (level C) Results and discussion: We found complete data regarding 556 primary transports 141 patients were escorted by emergency technicians only, 269 by doctor or nurse only, and 146 by a doctor and nurse. TS level A was found to have Ss 85,78%, Sp 70,92%, PPV 89,67% and NPV 62,89% regarding escort by emergency technicians only. These values support the decision of taking no medical escort in a primary transport in the pre-hospital setting when TS is level A. On the other hand, TS level C has Ss 78,08%, Sp 59,72%, PPV 40,57% and NPV 88,36% regarding escort by both a doctor and nurse. These numbers are less clear regarding a decision to take a medical escort. Conclusions: TS appears to be an indicator with enough Ss and Sp to help the pre-hospital team choose whether or not to escort the patient to the hospital with only emergency technicians or with a more differentiated escort, especially when the score’s result is Level A. But it cannot differentiate between doctor or nurse or both doctor and nurse when the result is level B or C. More figures are needed to understand if this score can be implemented as a decision tool regarding the kind of medical escort a patient needs in a primary transport.info:eu-repo/semantics/publishedVersio

    Bleaching of sol-gel glass film with embedded gold nanoparticles by thermal poling

    No full text
    Gold clusters embedded in glass are expected to be hard to dissolve in the form of ions since gold is essentially a nonreactive metal. In spite of that, bleaching of Au-doped nanocomposite sol-gel glass film on a soda-lime glass substrate is demonstrated in which electric-field thermal poling is employed to effectively dissolve randomly distributed gold nanoparticles (15 nm in diameter) embedded in a low conductivity sol-gel glass film with a volume filling factor as small as 2.3%. The surface plasmon absorption band at 520 nm is suppressed in the region covered by the anodic electrode. The phenomenon is explained by the ionization of the gold nanoparticles and the redistribution of gold ions in the glass matrix due to the action of the extremely high electrostatic field locally developed during poling
    corecore