537 research outputs found

    Factorization and Sudakov Resummation in B -> gamma l nu

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    We apply Soft-Collinear Effective Theory to prove at leading power in Lambda_QCD/m_b a factorization formula for the radiative leptonic decay B -> gamma l nu. Large logarithms entering the hard-scattering kernel are systematically resummed by a two-step perturbative matching procedure.Comment: 3 pages, 1 figure; contribution to proceedings of "International Europhysics Conference on High Energy Physics" EPS (July 17th-23rd 2003) in Aachen; to appear in European Physical Journal C direc

    CKM Overview and Determinations from B Decays

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    This talk gives an introduction to the Standard Model Cabibbo-Kobayashi-Maskawa matrix and methods to extract information on the parameters of the unitarity triangle from B decays.Comment: Contributed to XXXXth Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, March 5-12 200

    Increasing numbers of human infections with hantaviruses: further information for ornithologists and fieldbiologists

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    Hantaviruses are transmitted to humans by infected rodents via faeces, urine or bites and cause severe illness. In Europe the most common disease is the nephropathia epidemica. Man can be infected by inhaling viruses in contaminated aerosols or soil particles. There has been a obvious increase of case numbers in Germany in 2007: more than 1660 cases where recorded by the Robert-Koch-Institut (vs. 72 in 2006 and 448 in 2005). Mostly working men where concerned. 60 % of all patients had to be treated in hospital and 49 % had disorders of the kidney function. Contact to mice and their excreta has been identified as a relevant risk factor. To avoid infections ornithologists and fieldbiologists must be careful when working in areas inhabited by rodents (in Europe especially Bank voles), working with rodents or rodent eating birds and their pellets. Rodents should be kept year-round strictly out of all living areas and contact to rodents should be reduced or avoided. Gloves, face-masks and safety goggles must be used when working under dusty conditions. Hands must be cleaned consequently after work with water and soap (30 seconds) and desinfection should be used. Hantaviruses of the most common type in Europe (Puumala) can stay alive 5 to 15 days at room temperature and up to 18 days at 4°C. So pellets can by examinated without any risk after a quarantine period of two weeks or when heated up in the oven. Bird faeces and bird carcasses do not contain hantaviruses.Hantaviren als eine zwischen Nagetieren und Menschen übertragbare Zoonose spielen in den letzten Jahren in Mitteleuropa eine immer größere Rolle. Aufgrund der deutlichen Zunahme gemeldeter Erkrankungen in jüngster Zeit erscheint es angebracht, nochmals auf diese Infektionskrankheit, ihre Übertragungswege und vor allem Vorsichtsmaßnahmen für Vogelkundler und Feldbiologen hinzuweisen. Die nachfolgende Übersichtsarbeit fasst den aktuellen Kenntnisstand aus der Literatur zusammen (Robert-Koch-Institut 2005, 2006 a-d, 2007 a-c, 2008)

    When wrens go to sleep: Behaviour of a single winter wren Troglodytes troglodytes at its roost in winter

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    Ab den ersten Frostnächten im Herbst bilden Zaunkönige Schlafplatzgemeinschaften, bei denen mehrere Vögel zusammen in einem Unterschlupf nächtigen. An einem solchen Schlafplatz in einer Holzbetonnisthöhle wurde mit einer Überwachungskamera das Schlafverhalten eines einzelnen Zaunkönigs in einer 15 Stunden langen frostigen Novembernacht beobachtet. Die Nistkastenbesetzung erfolgt um Sonnenuntergang mit der Inspektion des Schlafplatzes durch zwei Vögel. Dabei kommunizieren die Zaunkönige innerhalb des Kastens mit gereihten tickenden Lauten, wie sie sonst im Feld nicht zu hören sind. Von diesen nur selten in der Literatur erwähnten Lautäußerungen wird ein Sonagramm gezeigt. Da ein Vogel den Kasten wieder verlässt belegt dieser Beobachtungstag, dass auch nur ein Vogel einen traditionellen Gemeinschaftsschlafplatz alleine nutzen kann. Zum Schlafen nimmt der Zaunkönig eine thermoregulatorisch günstige Kugelform ein und unterbricht den Schlaf immer wieder zur Gefiederpflege, Wechsel der Schlafposition und einmal zur Kotabgabe. Morgens verlässt der Vogel nach kurzem Strecken und Flügeldehnen 42 Minuten vor Sonnenaufgang den Nistkasten. Die Arbeit dokumentiert mit über 30 Fotos erstmals das nächtliche Verhalten eines Zaunkönigs und zeigt, dass mit Hilfe einfacher Überwachungstechnik völlig neue Einblicke in das Leben von Wildtieren möglich geworden sind.In chilly winter nights wrens start „cluster roosting“ as a response to low temperatures in suitable locations. Up to 18 wrens used a wooden concrete nestbox for roosting, which was prepared with a monitoring camera. We can therefore report on what wrens are doing during 15 hours of a winter night. In the first frosty November night two birds visited the nestbox at sunset but only one wren stayed for the night. This paper reports on the behaviour of this single winter wren roosting in an old sparrow nest. When the two birds investigated the nestbox they communicated with series of quiet „ick-ick“-calls (sonogram is shown). There was no evidence of aggressive interspecific behaviour. When arriving at the roost the wrens were restless, entering and leaving the nestbox several times. They appeared to check the roosting site and to look for conspecifics. The remaining bird slept in a puffed up ball shape for optimal thermoregulation. Sleeping was disrupted several times at night for changing sleeping position, preening and at one time for defaecating. In the morning the bird left the nest box after stretching and preening, 42 minutes before sunrise. The observed behaviour is illustrated by more than 30 images and documents that monitoring cameras can give us new insights into the hidden life of little songbirds and other animals

    Background information about Avian Infl uenza and hints for ornithologists

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    Wildvögel, v.a. Wassergeflügel, sind Reservoir für alle Influenzaviren. Von wirtschaftlicher Bedeutung sind die Subtypen H5 und H7, während H1, H2 und H3 Erreger der Humangrippe sind. Diese niedrig pathogenen Vogelgrippeviren verursachen normalerweise bei infi zierten Vögeln keine klinischen Symptome. Nach Transfer niedrig pathogener Vogelgrippeviren in Geflügelhaltungen mit den daraus resultierenden, rasch aufeinander folgenden Virenzyklen durch rasche Vogelpassagen und sofortige Neuinfektion kann sich ein solches niedrig pathogenes Virus jedoch in ein hoch pathogenes Vogelgrippevirus (HPAI-Virus) umwandeln. Diese hoch pathogenen Viren können dann sowohl wieder über Wildvögel, als auch über Transport kontaminierter Vögel, Gefl ügelprodukte und Materialien sowie über Wasser weiterverbreitet werden. Der aktuelle, große Ausbruch der Gefl ügelgrippe geht auf den HPAI-Virus H5N1 zurück, der vermutlich in den späten 1990er Jahren in Hausenten in Südchina entstanden ist. Im Jahr 2005 begann diese Krankheit, sich von Südostasien aus westwärts zu verbreiten und trat damit als direkte Bedrohung für europäische Geflügelbestände in Erscheinung. Außerdem wurden einige wenige menschliche Fälle einer HPAI H5N1-Erkrankung aus Südostasien gemeldet. Alle diese menschlichen Erkrankungen standen mit sehr engen Kontakten zu oder Verspeisen von infizierten Tieren (vor allem Hühner, Enten und Schweine) in Verbindung und eine mögliche Mensch-zu-Mensch-Übertragung wird noch kontrovers diskutiert. Obwohl die Vogelgrippe nach wie vor eine Geflügelkrankheit ist, besteht die Möglichkeit, dass sich das Virus in seiner genetischen Struktur – z.B. durch Vermischung mit einem Humangrippevirus – so verändern kann, dass es leicht zwischen Menschen übertragen werden kann und bei diesen auf ein weitgehend unvorbereitetes Immunsystem trifft. Obwohl sich die Wahrscheinlichkeit einer solchen Veränderung nicht abschätzen lässt, liefern drei Pandemien im 20 Jahrhundert, die alle auf mutierte Vogelgrippeviren zurückzuführen sind, genug Anlass zur sorgfältigen Beobachtung der momentanen Lage.Waterfowl are known to be the major reservoir for all 16 H- and 9 N- Subtypes of low pathogenic avian infl uenza viruses (LPAIV), including the subtypes H5 and H7 being a serious economic threat to the poultry industry as well as H1, H2, H3 that are the main source for human infl uenza. LPAI neither cause any signs of disease in the infected wild birds nor in poultry. However, low pathogenic avian infl uenza virus of the subtypes H5 and H7 can be introduced into poultry holdings. Especially in industrial holdings with large numbers of highly susceptible animals, the previously stable viruses of low pathogenicity begin to evolve rapidly and may mutate into highly pathogenic avian infl uenza (HPAI) (known as fowl plague and also called „bird flu“) causing up to 100% mortatlity in infected birds. Aft erwards, infections of HPAI are usually spread by movement of stock, infectious feces, contaminated water or bird products. Free fl ying birds are usually also blamed to spread the disease, but this could be never proven to have happened. Since 1959 none of the outbreaks of HPAI has approached the size of the ongoing epizootic in Southeast Asia, which most probably originated in the late 1990 ies presumbly in captured ducks in Southern China and is caused by a new HPAI virus of the subtype H5N1. In 2005 the disease started to spread westwards and appears to be a threat for European poultry. Th e asian H5N1 cause serious public health concern for at least three reasons. Th ese AIV isolates can cause heavy economic losses in the poultry industry and through loss of poultry may exaggerate to human food protein defi cits in the developing world. In addition, they have the potential to cross the species barriers and cause human disease and death though only when connected to very close contacts with infected animals or raw consumption of infected birds (chicken, ducks). Last but not least there is the potential of the virus to change it‘s genetic structure – most probably by mixing with a human infl uenza virus (H1, H2, H3) that may achieve human-to-human spread by meeting the unprepared immune system of men resulting in a new human pandemia. Th ree pandemias during the 20 th century – all originating from HPAI viruses- emphasise the danger of the probability of H5N1 becoming the next pandemia virus

    Exclusive Radiative Decays of B Mesons

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    We present within the Standard Model the exclusive radiative decays B -> K*/rho gamma and B_(s/d) -> gamma gamma in QCD factorization based on the heavy-quark limit m_b >> Lambda_QCD. For the decays with a vector meson in the final state we give results complete to next-to-leading order in QCD.Comment: 4 pages, contributed to QCD 02: High-Energy Physics International Conference in Quantum Chromodynamics, Montpellier, France, 2-9 July 200

    Super-directional light emission and emission reversal from micro cavity arrays

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    Optical microdisk cavities with certain asymmetric shapes are known to possess unidirectional far-field emission properties. Here, we investigate arrays of these dielectric microresonators with respect to their emission properties resulting from the coherent behaviour of the coupled constituents. This approach is inspired by electronic mesoscopic physics where the additional interference effects are known to enhance the properties of the individual system. As an example we study the linear arrangement of nominally identical Lima\c{c}on-shaped cavities and find mostly an increase of the portion of directional emitted light while its angular spread is largely diminished from 20 degrees for the single cavity to about 3 degrees for a linear array of 10 Lima\c{c}on resonators, in fair agreement with a simple array model. Moreover, by varying the inter-cavity distance we observe windows of reversion of the emission directionality and super-directionality that can be interesting for applications. We introduce a generalized array factor model that takes the coupling into account.Comment: 5 pages, 5 figures, supplemental materia

    General Lower Bounds for b -> d Penguin Processes

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    For the exploration of flavour physics, b -> d penguin processes are an important aspect, with the prominent example of \bar B^0_d -> K^0 \bar K^0. We recently derived lower bounds for the CP-averaged branching ratio of this channel in the Standard Model; they were found to be very close to the corresponding experimental upper limits, thereby suggesting that \bar B^0_d -> K^0 \bar K^0 should soon be observed. In fact, the BaBar collaboration subsequently announced the first signals of this transition. Here we point out that it is also possible to derive lower bounds for \bar B -> \rho \gamma decays, which are again surprisingly close to the current experimental upper limits. We show that these bounds are realizations of a general bound that holds within the Standard Model for b -> d penguin processes, allowing further applications to decays of the kind B^\pm -> K^{(\ast)\pm} K^{(\ast)} and B^\pm -> \pi^\pm \ell^+ \ell^-, \rho^\pm \ell^+ \ell^-.Comment: Minor changes, to appear as rapid communication in Phys. Rev

    Wave Monitoring with Wireless Sensor Networks

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    Real-time collection of wave information is required for short and long term investigations of natural coastal processes. Current wave monitoring techniques use only point-measurements, which are practical where the bathymetry is relatively uniform. We propose a wave monitoring method that is suitable for places with varying bathymetry, such as coral reefs. Our solution uses a densely deployed wireless sensor network, which allows for a high spatial resolution and 3D monitoring and analysis of the waves. The wireless sensor nodes are equipped with low-cost, low-power, MEMS-based inertial sensing. We report on lab experiments with a Ferris wheel contraption, which is a technique used in practice to evaluate and calibrate the state-of-the-art wave monitoring solutions.\u

    Usutu Virus as cause of mass mortality in Blackbirds Turdus merula and other bird species in Europe: experiences from five outbreaks between 2001 and 2011

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    Das Usutu-Virus (USUV) ist ein durch Stechmücken der Gattung Culex übertragenes Flavivirus. Es wurde wahrscheinlich durch Zugvögel oder Stechmücken nach Europa eingeschleppt und hat sich inzwischen dauerhaft in der einheimischen Stechmücken-und Vogelfauna etabliert. Seit seinem Erstnachweis 2001 in Österreich hat das USUV fünf größere Ausbrüche mit USUV-assoziierten Vogelsterben, vor allem unter Amseln und in Volieren gehaltenen Eulen, sowie vermutlich kleinere Ausbrüche ohne augenfälliges Vogelsterben verursacht. In unserer Übersicht stellen wir das aktuelle Wissen zum Erreger, den Stechmücken als Vektoren und den Vögeln als Hauptwirten vor. Die Auswertung bislang publizierter Studien ergab, dass in der letzten Dekade in Europa, im Zusammenhang mit USUV-Ausbrüchen, über 3050 Vogelindividuen aus 129 Arten und unterschiedlichsten Ordnungen auf USUV-Infektionen untersucht worden sind. Davon wurden 48 Arten positiv getestet, überwiegend Singvögel, Eulen und Greifvögel. Am häufigsten war die Amsel, danach Haussperling, Mönchsgrasmücke, Bart- und Habichtskauz betroffen. Unter den 48 USUV-positiven Arten betrafen 39 frei lebende und neun in Gefangenschaft gehaltene Arten. Mögliche Ausbreitungswege des Erregers von Afrika nach Europa sowie innerhalb Europas werden diskutiert. Amseln und andere Singvögel sind anscheinend besonders anfällig für USUV. Möglicherweise sind sie zur Hauptflugzeit der Stechmücken aufgrund ihres Mauser- und Ernährungszustandes immungeschwächt und anfälliger für einen Virenbefall.Usutu virus (USUV) is a flavivirus transmitted by mosquitoes of the genus Culex. USUV was presumably introduced into Europe through migrating birds or mosquitoes during the last ten years. USUV established stable transmission cycles in Europe between mosquitos and hosts and is able to hibernate within Europe. Since the first record in 2001 in Austria, USUV caused five larger outbreaks with USUV-induced mass mortalities, especially on Blackbirds and captive owls, and probably a number of smaller outbreaks without recorded mass mortality. In our review we compile the up-to-date knowledge about the agent, the mosquitos as vectors and the birds as main hosts. A review of published studies revealed a total of 3050 bird individuals from 129 species and a wide variety of orders that have been tested for USUV during the last decade in Europe in connection with USUV outbreaks. Out of these, 48 species have been tested positively – mainly songbirds incl. crows (24 species), owls and birds of prey (9 species). Most cases concerned Blackbird, followed by House Sparrow, Blackcap, Great Grey Owl and Ural Owl. Among the 48 species tested positively, 39 concerned free living individuals and nine concerned captive individuals. Potential ways of propagation of USUV from Africa into Europe as well as inside Europe are discussed. Blackbirds seem to be especially perceptive to USUV. With regard to their species-specific biology we try to give an explanation for this phenomenon: presumably, Blackbirds have a weak immune system due to moult and nutrition state during the main flight period of the mosquitoes and are thus more perceptive to virus attacks
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