345 research outputs found

    Evaluation of the discovery potential of an underwater Mediterranean neutrino telescope taking into account the estimated directional resolution and energy of the reconstructed tracks

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    We report on the development of search methods for point-like and extended neutrino sources, utilizing the tracking and energy estimation capabilities of an underwater, Very Large Volume Neutrino Telescope (VLVnT). We demonstrate that the developed techniques offer a significant improvement on the telescope's discovery potential. We also present results on the potential of the Mediterranean KM3NeT to discover galactic neutrino sources.Comment: 12 pages, 1 figure, to be published in Nucl. Inst. and Meth. A v2: minor changes, 1 page adde

    From dense-dilute duality to self duality in high energy evolution

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    I describe recent work on inclusion of Pomeron loops in the high energy evolution. In particular I show that the complete eikonal high energy evolution kernel must be selfdual.Comment: Talk given at DIS05, April 2005, Madiso

    Charged Higgs boson contribution to ντNτX\nu_{\tau} {\cal N} \to \tau^- X for very large tanβ\tan\beta in the two Higgs doublet model with UHE-neutrinos

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    We study the deep inelastic process ντ+Nτ+X\nu_{\tau} + {\cal N} \to \tau^{-} + X (with N(n+p)/2{\cal N} \equiv (n+p)/2 an isoscalar nucleon), in the context of the two Higgs doublet model {\it type two} (2HDM(II)). In particular, we discuss the contribution to the total cross section of diagrams, in which a charged Higgs boson is exchanged. We show that for large values of tanβ\tan\beta such contribution for an inclusive dispersion generated through the collision of an ultrahigh energy tau-neutrino on a target nucleon can reach up to 57% of the value of the contribution of the W+W^+ exchange diagrams (i.e. can reach up to 57% of the standard model (SM) prediction) and could permit to distinguish between the SM and the 2HDM(II) predictions at the Pierre Auger Observatory.Comment: 10 pages, 5 figure

    Shadowing of Ultrahigh Energy Neutrinos

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    The rise with energy of the neutrino--nucleon cross section implies that at energies above few TeV the Earth is becoming opaque to cosmic neutrinos. The neutrinos interact with the nucleons through the weak charged current, resulting into absorption, and the weak neutral current, which provides a redistribution of the neutrino energy. We Mellin transform the neutrino transport equation and find its exact solution in the moment space. A simple analytical formula is provided, which describes accurately the neutrino spectrum, after the neutrinos have traversed the Earth. The effect of the weak neutral current is most prominent for an initial flat neutrino spectrum and we find that at low energies (around 1 TeV) the neutrino intensity is even enhanced.Comment: gziped, tar file of LaTeX paper plus 2 postscript figures, 13 page

    Phenomenology of quintessino dark matter -- Production of NLSP particles

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    In the model of quintessino as dark matter particle, the dark matter and dark energy are unified in one superfield, where the dynamics of the Quintessence drives the Universe acceleration and its superpartner, quintessino, makes up the dark matter of the Universe. This scenario predicts the existence of long lived τ~\tilde{\tau} as the next lightest supersymmetric particle. In this paper we study the possibility of detecting τ~\tilde{\tau} produced by the high energy cosmic neutrinos interacting with the earth matter. By a detailed calculation we find that the event rate is one to several hundred per year at a detector with effective area of 1km21 km^2. The study in this paper can be also applied for models of gravitino or axino dark matter particles.Comment: 16 pages, 5 figures, a new section about NLSP stau is added, references adde

    Early vertical distribution of roots and its association with drought tolerance in tropical maize

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    Background and aims: Selection for deep roots to improve drought tolerance of maize (Zea mays L.) requires presence of genetic variation and suitable screening methods. Methods: We examined a diverse set of 33 tropical maize inbred lines that were grown in growth columns in the greenhouse up to the 2-, 4-, and 6-leaf stage and in the field in Mexico. To determine length of roots from different depths at high throughput, we tested an approach based on staining roots with methylene blue and measuring the amount of absorbed dye as proxy measure for root length. Results: Staining provided no advantage over root weights that are much easier to measure and therefore preferable. We found significant genotypic variation for all traits at the 6-leaf stage. For development rates between the 2-leaf and the 6-leaf stage, genotypes only differed for rooting depth and the number of crown roots. Positive correlations of leaf area with root length and rooting depth indicated a common effect of plant vigor. However, leaf area in growth columns was negatively related to grain yield under drought (r = −0.50). Conclusion: The selection for deeper roots by an increase in plant vigor likely results in a poorer performance under drought conditions. The proportion of deep roots was independent of other traits but showed a low heritability and was not correlated to field performance. An improved screening protocol is proposed to increase throughput and heritability for this trait

    The use of cosmic muons in detecting heterogeneities in large volumes

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    The muon intensity attenuation method to detect heterogeneities in large matter volumes is analyzed. Approximate analytical expressions to estimate the collection time and the signal to noise ratio, are proposed and validated by Monte Carlo simulations. Important parameters, including point spread function and coordinate reconstruction uncertainty are also estimated using Monte Carlo simulations.Comment: 8 pages, 11 figures, submetted to NIM

    Atmospheric MUons from PArametric formulas: a fast GEnerator for neutrino telescopes (MUPAGE)

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    Neutrino telescopes will open, in the next years, new opportunities in observational high energy astrophysics. For these experiments, atmospheric muons from primary cosmic ray interactions in the atmosphere play an important role, because they provide the most abundant source of events for calibration and test. On the other side, they represent the major background source. In this paper a fast Monte Carlo generator (called MUPAGE) of bundles of atmospheric muons for underwater/ice neutrino telescopes is presented. MUPAGE is based on parametric formulas [APP25(2006)1] obtained from a full Monte Carlo simulation of cosmic ray showers generating muons in bundle, which are propagated down to 5 km w.e. It produces the event kinematics on the surface of a user-defined virtual cylinder, surrounding the detector. The multiplicity of the muons in the bundle, the muon spatial distribution and energy spectrum are simulated according to a specific model of primary cosmic ray flux, with constraints from measurements of the muon flux with underground experiments. As an example of the application, the result of the generation of events on a cylindrical surface of 3 km^2 at a depth of 2450 m of water is presented.Comment: 20 pages, 4 figure

    CELP ALGORITHMAND IMPLEMENTATION FORSPEECHCOMPRESSION

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    ABSTRACT This paper describes a fast algorithm and implementation of code excited linear predictive (CELP) speech coding. It presents principles of the algorithm, including (i) fast conversion of line spectrum pair parameters to linear predictive coding parameters, and (ii) fast searches of the parameters of adaptive and stochastic codebooks. The algorithm can be readily used for speech compression applications, such as on (i) high quality low-bit rate speech transmission in pointto-point or store-and-forward (network based) mode, and (ii) efficient speech storage in speech recording or multimedia databases. The implementation performs in real-time and near real-time on various platforms, including an IBM-PC AT equipped with a TMS32OC30 module, an IBM PC 486, a SUN Sparcstation 2, a SUN Sparcstation 5, and an IBM Power PC (Power 590). l. INTRODUCTION Why is CELP Useful ? Obtaining efficient representation of speech at low bit rates for communication or storage has been a problem of considerable importance, because of technical as well as economical requirements. Telephone-quality digital speech in a pulse code modulation (PCM) form requires a 64 kbits/s rate which cannot be transmitted in real time through 6 kHz and 30 kHz channel capacities of HF and VHF bands, respectively. Voice mail and multimedia employ speech storage, demanding efficient ways of storing speech, since one minute of PCM speech already requires 480 kbytes of storage space. Even if the channel can accommodate real-time speech, speech compression allows more communication connections to share the precious channel. Similarly, speech compression allows more speech messages to be stored in the storage of the same size. This paper describes a speech compression technique for those purposes, called code-excited linear predictive (CELP) coding [Atal86] [JlaJS93], which obtains bit rates of as low as 4.8 kbits/s, giving a compression ratio of up to 13: 1 The importance of CELP goes beyond its quality vs. bit-rate performance, as it *provides a generic structure for future generation of' perceptual speech coders If further compression iIs still required, the coder minimizes the error perceptibility by exploiting masking properties of human speech perception. To certain extent, the speech energy itself perceptually masks the distortion. Thus the same energy levels of distortion have different perceptual effect if applied to speech signals with different energy levels. This approach promises a new level of highier quality and lower bit rate speech compression One novelty of CELP is in incorporating the masking property in a working, practical scheme. Such incorporation is non trivial blecause perceptual distortion measures lack tractable means that have often been available in the traditional distortion energy measure. 9

    "Medikamente sind Bomben" - zum Metapherngebrauch von Lungentransplantations-Patienten mit guter oder ungenügender Compliance

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    Fragestellung: Nach einer Organtransplantation finden komplexe psychologische Verarbeitungsprozesse statt. In der vorliegenden Studie wurde untersucht, welche Metaphern im Zusammenhang mit Transplantationserfahrungen verwendet werden, und ob Unterschiede zwischen Patienten mit guter bzw. ungenügender Compliance im Gebrauch dieser Metaphern bestehen. Methode: 14 lungentransplantierte Patienten wurden in einem halbstrukturierten Interview zu ihren Transplantationserfahrungen befragt. Ihre Compliance wurde von den behandelnden Ärzten eingeschätzt. Die Auswertung der Interviews erfolgte anhand einer Metaphernanalyse, welche Hinweise auf vor- und unbewusste Vorstellungen der Patienten liefert. Die Interraterreliabilität über die Metapherngruppen war Cohen’s Kappa K = 0.8. Ergebnisse: Die Patienten konzeptualisierten ihren Körper, aber auch ihr Selbst als ein “Gefäß”, dass sowohl materielle (z.B. die Lunge) wie immaterielle Objekte (z.B. Gedanken an den Spender, Affekte) enthält. Der wichtigste Unterschied zwischen den Compliance-Gruppen bestand darin, dass Patienten mit ungenügender Compliance eine grössere Distanz zur transplantierten Lunge erlebten. Auch konzeptualisierten sie ihren Körper bzw. ihr Selbst nicht als ein Gefäß, das die Lunge enthält. Diskussion: Die Ergebnisse zeigen, dass gute Compliance mit einer erfolgreichen Organintegration assoziiert ist, welche die Zugehörigkeit der Lunge in einem als Gefäß konzeptualisierten Körper bzw. Selbst umfasst. Patienten mit ungenügender Compliance nehmen die Lunge eher als Fremdkörper wahr. Diese Verarbeitungsprozesse sind teils bewusster, teils vor- und unbewusster Natur
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