Some relationships between the geometry of the tangent bundle and the geometry of the Riemannian base manifold

We compute the curvature tensor of the tangent bundle of a Riemannian manifold endowed with a natural metric and we get some relationships between the geometry of the base manifold and the geometry of the tangent bundle.Fil: Henry, Guillermo Sebastian.Fil: Guillermo Keilhauer

Air Fluorescence Relevant for Cosmic-Ray Detection - Summary of the 5th Fluorescence Workshop, El Escorial 2007

High-energy cosmic rays with energies exceeding $10^{17}$ eV are frequently observed by measurements of the fluorescence light induced by air showers. A major contribution to the systematic uncertainties of the absolute energy scale of such experiments is the insufficient knowledge of the fluorescence light yield of electrons in air. The aim of the 5th Fluorescence Workshop was to bring together experimental and theoretical expertise to discuss the latest progress on the investigations of the fluorescence light yield. The results of the workshop will be reviewed as well as the present status of knowledge in this field. Emphasis is given to the fluorescence light yield important for air shower observations and its dependence on atmospheric parameters, like pressure, temperature, and humidity. The effects of the latest results on the light observed from air showers will be discussed.Comment: Nucl. Instr. & Meth. in pres

Accurate Protein Complex Retrieval by Affinity Enrichment Mass Spectrometry (AE-MS) Rather than Affinity Purification Mass Spectrometry (AP-MS)

Protein-protein interactions are fundamental to the understanding of biological processes. Affinity purification coupled to mass spectrometry (AP-MS) is one of the most promising methods for their investigation. Previously, complexes were purified as much as possible, frequently followed by identification of individual gel bands. However, todays mass spectrometers are highly sensitive, and powerful quantitative proteomics strategies are available to distinguish true interactors from background binders. Here we describe a high performance affinity enrichment-mass spectrometry method for investigating protein-protein interactions, in which no attempt at purifying complexes to homogeneity is made. Instead, we developed analysis methods that take advantage of specific enrichment of interactors in the context of a large amount of unspecific background binders. We perform single-step affinity enrichment of endogenously expressed GFP-tagged proteins and their interactors in budding yeast, followed by single-run, intensity-based label-free quantitative LC-MS/MS analysis. Each pull-down contains around 2000 background binders, which are reinterpreted from troubling contaminants to crucial elements in a novel data analysis strategy. First the background serves for accurate normalization. Second, interacting proteins are not identified by comparison to a single untagged control strain, but instead to the other tagged strains. Third, potential interactors are further validated by their intensity profiles across all samples. We demonstrate the power of our AE-MS method using several well-known and challenging yeast complexes of various abundances. AE-MS is not only highly efficient and robust, but also cost effective, broadly applicable, and can be performed in any laboratory with access to high-resolution mass spectrometers

Measurements of the Muon Content of UHECR Air Showers with the Pierre Auger Observatory

The Pierre Auger Observatory, recently completed, has been operational since 2004. As a hybrid experiment, it allows for a wide range of measurements of UHECR-induced extensive air showers (EAS), including measurements of the EAS particle content on ground which is sensitive to high-energy hadronic interactions. We present the results of several independent measurements of the EAS muon content on ground in Auger data at a primary energy of 10 EeV. We discuss implications on high-energy hadronic interaction models and cosmic ray composition.Comment: 6 pages, 5 figures; proceedings of ISVHECRI 2008 - XV International Symposium on Very High Energy Cosmic Ray Interaction

Nitrogen fluorescence in air for observing extensive air showers

Extensive air showers initiate the fluorescence emissions from nitrogen molecules in air. The UV-light is emitted isotropically and can be used for observing the longitudinal development of extensive air showers in the atmosphere over tenth of kilometers. This measurement technique is well-established since it is exploited for many decades by several cosmic ray experiments. However, a fundamental aspect of the air shower analyses is the description of the fluorescence emission in dependence on varying atmospheric conditions. Different fluorescence yields affect directly the energy scaling of air shower reconstruction. In order to explore the various details of the nitrogen fluorescence emission in air, a few experimental groups have been performing dedicated measurements over the last decade. Most of the measurements are now finished. These experimental groups have been discussing their techniques and results in a series of Air Fluorescence Workshops commenced in 2002. At the 8$^{\rm{th}}$ Air Fluorescence Workshop 2011, it was suggested to develop a common way of describing the nitrogen fluorescence for application to air shower observations. Here, first analyses for a common treatment of the major dependences of the emission procedure are presented. Aspects like the contributions at different wavelengths, the dependence on pressure as it is decreasing with increasing altitude in the atmosphere, the temperature dependence, in particular that of the collisional cross sections between molecules involved, and the collisional de-excitation by water vapor are discussed.Comment: 12 pages, 17 figures, 2 tables, International Symposium on Future Directions in UHECR Physics, 13-16 February 2012, CERN, Geneva (Switzerland); the updated version corrects for a typo in Eq. (1

Atmospheric Calorimetry above 1019^{19} eV: Shooting Lasers at the Pierre Auger Cosmic-Ray Observatory

The Pierre Auger Cosmic-Ray Observatory uses the earth's atmosphere as a calorimeter to measure extensive air-showers created by particles of astrophysical origin. Some of these particles carry joules of energy. At these extreme energies, test beams are not available in the conventional sense. Yet understanding the energy response of the observatory is important. For example, the propagation distance of the highest energy cosmic-rays through the cosmic microwave background radiation (CMBR) is predicted to be strong function of energy. This paper will discuss recently reported results from the observatory and the use of calibrated pulsed UV laser "test-beams" that simulate the optical signatures of ultra-high energy cosmic rays. The status of the much larger 200,000 km$^3$ companion detector planned for the northern hemisphere will also be outlined.Comment: 6 pages, 11 figures XIII International Conference on Calorimetry in High Energy Physic

Atmospheric aerosols at the Pierre Auger Observatory and environmental implications

The Pierre Auger Observatory detects the highest energy cosmic rays. Calorimetric measurements of extensive air showers induced by cosmic rays are performed with a fluorescence detector. Thus, one of the main challenges is the atmospheric monitoring, especially for aerosols in suspension in the atmosphere. Several methods are described which have been developed to measure the aerosol optical depth profile and aerosol phase function, using lasers and other light sources as recorded by the fluorescence detector. The origin of atmospheric aerosols traveling through the Auger site is also presented, highlighting the effect of surrounding areas to atmospheric properties. In the aim to extend the Pierre Auger Observatory to an atmospheric research platform, a discussion about a collaborative project is presented.Comment: Regular Article, 16 pages, 12 figure